Department of Electrical and Computer Engineering University of Waterloo 200 University Avenue West Waterloo, Ontario, N2L 3G1 Canada  

 

 The annual report provides a detailed documentation for the year 2007 of the research projects and other activities accomplished by the RF/Microwave/Photonics Research Group in the Department of Electrical and Computer Engineering. It highlights research activities, publications, grants, awards, and other pertinent information about the group members and activities.

 

2007 Annual Report RF/Microwave/Photonics Research Group

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RF/Microwave/Photonics Research Group

A. Hamed Majedi Assistant Professor

Raafat Mansour Professor NSERC/COMDEV Industrial Research Chair

Sujeet Chaudhuri Professor Val O'Donovan Chair  

Slim Boumiaza Assistant Professor

Omar M. Ramahi Professor RIM/NSERC Industrial Research Associate Chair

Safieddin Safavi-Naeini Professor RIM/NSERC Industrial Research Chair

Simarjeet Singh Saini Assistant Professor

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Slim Boumaiza, Assistant Professor, received the B.Eng. degree in electrical engineering from the École Nationale d'Ingénieurs de Tunis, Tunis, Tunisia, in 1997, and the M.S. and Ph.D. degrees from the École Polytechnique de Montréal, Canada, in 1999 and 2004. He joined recently the Electrical and Computer Engineering Department at the University of Waterloo, Canada, where he is leading the Emerging Radio System Research Group which is conducting multidisciplinary research activities in the general areas of design of RF/microwave and millimeter components and systems for wireless and satellite communications. From May 2005 to August 2007, he was with the Electrical Engineering Department, University of Calgary, Canada, as an Assistant Professor and faculty member of the Intelligent RF Radio Laboratory. His specific current interests include RF/DSP mixed design of intelligent RF transmitters, design, characterization, modeling and linearization of high-power RF amplifiers, reconfigurable and multi-band transceivers and adaptive DSP.

Dr. Boumaiza founded the Emerging Radio Systems Group (EmRG), in August 2007, at the Electrical and Computer Engineering Department of the University of Waterloo, that focuses on the creation of enabling approaches for the synthesis of highly functional circuitries which are essential for the development of new software-enabled radios suitable for ubiquitous and cognitive wireless communication networks. Included here are linear and power efficient power amplifiers, signal generation and synthesis, frequency converters, and advanced baseband digital signal processing algorithms. The EmRG’s device to circuit to system levels oriented research activities are strongly triggered by wireless industry needs and the long-term technology roadmap.

Research Projects

Software defined radio (SDR) technology is propelling innovation in wireless communication by enabling universal communication devices with the

capability to adapt to the user environment and needs “on-the-fly”. It is also propping up the development of Cognitive Radios (CR) that looks to the radiofrequency spectrum utilization, in their immediate neighborhood, and configure themselves for best performance. In other words, software defined and cognitive radios will enable global-interoperability and dynamic spectrum management of emerging ubiquitous and cognitive communication networks.

Yet, SDR and CR development involves challenging requirements that are creating intriguing research and development opportunities in the general field of microwave and radiofrequency (MW/RF) circuit technologies. In particular, the EmRG’s research interests aim to advance the application of a mixed software/hardware co-design approach for the development of intelligent, flexible, cost effective and power efficient digitally reconfigurable radio architectures so that a single radio transceiver will be capable of coping with different requirements of diverse wireless standards, such as frequencies, modulation schemes and air interfaces through software programming. This includes the investigation of high-power efficiency and ultra-linear power amplifiers, multi-band and digitally reconfigurable transmitters, MW/RF circuits and systems modeling, and advanced signal processing algorithms.

1. High-Power Efficiency and Ultra-Linear Power Amplifiers

One of the most critical design criteria in designing wireless transmitters is the optimization of the power efficiency versus linearity trade-offs as these are usually inconsistent. Indeed, the nonlinear effects generally exhibited by the power amplifier stage of the transmitter lead to output spectral regrowth, co-channel interferences and degradation of the signal quality. Several linearization techniques have been proposed in the literature to compensate for the non-linear distortion generated by PAs when driven with modulated signals. Among these techniques digital

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baseband predistortion (DPD) is currently the most popular one as it is benefiting from the incessant progress in the digital signal processors (DSP and FPGA). DPD ideally aims to identify an inverse function of a nonlinear system, so that the cascade of the two produces a linear output function. Practically, the addition of the predistorter expands the linear range of operation of the power amplifier into a region of higher efficiency. Memoryless DPD showed good linearization capability when used with narrowband amplifiers. However, their performance is highly affected when emerging wideband signals are used as significant electrical memory effects are present. In such context, Memory Polynomial (MP) DPD, which requires much fewer coefficients than the general Volterra series, was proven to be an effective solution to mitigate the extra distortions caused by memory effects. In 2007, the complexity of the Memory Polynomial DPD was reduced by over a half by limiting the required number of unknown parameters while maintaining excellent linearization capability of 400Watt Doherty PA driven with a four carrier WCDMA signal. This allowed for easier implementation on FPGA and reduces the strain of the necessary numerical computation.

Moreover, in this topic, further technological developments are targeted at enhancing the transmitters’ power efficiency by investigating Switching Mode PAs (SMPA). These are currently enabled by the semiconductor technology progress. In 2007, we investigated the design of Class E and Class F SMPAs using the Gallium Nitride Transistors. Excellent power added efficiencies, as high as 80%, have been achieved. Currently, these high efficiency SMPAs are being incorporated into advanced transmitter architectures topologies, such as pulse width modulation based transmitters in order to develop linear and high efficiency schemes.

Furthermore, mode-multiplexing linear amplification with nonlinear components (MM-LINC) scheme was proposed for further efficiency enhancement of conventional LINC transmitters. For that, the

transmitter operates according to the LINC concept for input signal magnitude drive levels below a certain threshold and as a balanced amplifier beyond this threshold.

2. Microwave/Radio Frequency Circuits and Systems Modeling

Emerging wireless communications put forth broadband access requirements on radio systems. With an increased limitation in frequency spectrum allocations, high spectral modulation techniques and air interfaces have been devised which leaves the transmitted signals very susceptible to “dirty” (nonlinear and linear distortions) RF front ends. Modeling the front ends accurately and deploying an efficient and viable compensation techniques have been more and more challenging as the signals’ bandwidth increases. Therefore, understanding the nonlinearity sources in an RF system is essential, as it would aid optimizing the corresponding behavioral model topology, reducing its mathematical strain while meeting the performance required in terms of comprehensiveness and accuracy.

In 2007, we have been investigating linear and nonlinear distortion sources in the RF transmitter chains that compromise their performances. For that, a comprehensive and systematic characterization methodology that is suitable for the forward and reverse behavior modeling of wireless transmitters driven by wideband-modulated signals was developed. This characterization approach can be implemented in adaptive radio systems since it does not require particular signal or training sequences.

3. Multi­Band and Digitally Reconfigurable Transmitters 

The realization of SDR and CR poses many new technical challenges in the areas of protocol design, interference cancellation and quality of signal guarantees, environment awareness, base band algorithms and radio front-end realization. The SDR

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ideal realization involves wideband signal digitization which occurs next to the antenna and the rest of the radio processing is implemented in software running on a very fast processor. As such, the re-programmability is tailored to the radio communications and a generic hardware platform for different types of radio applications is enabled just by changing the software. However, the ideal SDR and CR are currently impractical due to current technology constraints such as the lack of ideal wideband analog to digital interfaces and limited processor speeds. Nevertheless, alternative architectures exist on which digitally reconfigurable radios (D2R) are suggested as a practical realization of SDR and CR front-ends.

In this topic, advanced D2R architectures suitable for cost effective and power efficient SDR and CR realization are being investigated to support the major wireless standards. This involves the development of new set of active (power amplifiers) and passive (combiners and filters) circuits that maintain high performances over a broad range of frequencies.

Three alternative approaches has been suggested for the design of a multi-band PA namely: (i) multiple PAs designed for each targeted discrete frequency operating in parallel, (ii) a single amplifier with wideband Matching Networks (MN) that covers all the targeted frequencies, (iii) a single amplifier with a reconfigurable MN. Using multiple power amplifiers is the least cost effective solution because it has a large bill of materials and more sources of loss attributed to power combiners. A power amplifier with a wideband MN encompassing all frequencies is not an adequate solution because it has low power efficiency and amplifies out-of-band frequencies. Using a reconfigurable MN can be seen as a good solution, but it does not allow operation at multiple frequencies concurrently. Furthermore, reconfigurable MNs often use components (such as Micro Electric Mechanical Systems (MEMS)) that are not yet capable of handling the output power necessary in base station applications. Hence, we

initiated the development of a single power amplifier that will operate at multiple frequencies concurrently. The moderate complexity of this design is justified because it requires a small bill of materials and it dramatically reduces the cost by using only one power amplifier. In a first stage, this research allowed the development of a systematic procedure to design a concurrent dual-band PA.

Furthermore, a number of extra successive frequency transformations and circuit conversions were added to conventional network synthesis approach for the design of a dual band band-pass filter suitable for dual band radiofrequency front ends. Furthermore, a compact wideband branch-line coupler was developed using conventional analysis followed by successive lumped distributed element circuit transformations and designed in micro-strip lines technology. It allowed a substantial reduction of radio frequency front ends size.

4. Adaptive Signal Processing Algorithms

Radio systems are generally made up of two major parts: the base band processor and the analog RF front end. The base band processor, which is implemented in combined field-programmable gate array (FPGA) and/or Digital Signal Processors (DSP) platforms, runs advanced digital signal processing algorithms for a run-time reconfiguration of the radio’s analog RF front-end, compensation for the impairments of the analog blocks (nonlinear and linear distortions), and enhancement of the system-level performance.

In this topic, new technique was devised for accurate estimation and compensation of I/Q imbalance in Quadrature Modulators and Demodulators used in direct conversion radio transceivers. This technique doesn’t necessitate a special training sequence as it uses the actual In-phase and Quadrature components of modulated signals at the input and output of the transmitter-under-test for adaptive determination of the modulator and demodulator imbalances. The accuracy of the new algorithm was carefully assessed and compared to the previous works.

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Furthermore, a WiMax transceiver baseband processor was designed and implemented in a FPGA platform. This processor is currently used for the development of a Multiple Input and Multiple Output test bench that will be used for the assessment of propagation channel under realistic modulated signals in indoor and outdoor environments.

Journal Publications

S. Boumaiza, M. Helaoui, O. Hammi, T. Liu, and F. M. Ghannouchi, “Systematic and Adaptive Characterization Approach for Behavior Modeling of Dynamic Nonlinear Transmitters”, IEEE Trans. on Instrumentation and Measurement, Vol. 56, No. 6, Dec. 2007, pp. 2203-2211. (9 pages)

O. Hammi, S. Boumaiza, F. M. Ghannouchi, “A Data Based Nested LUTs Model for RF Power Amplifiers Exhibiting Memory Effects”, IEEE Microwave and Wireless Components Letters, Vol. 17, Issue 10, Oct. 2007, pp. 712 – 714. (3 pages)

O. Hammi, S. Boumaiza, and F. M. Ghannouchi, “On the Robustness of Digital Predistortion Function Synthesis and Average Power Tracking for Highly Nonlinear Power Amplifiers”, IEEE Trans. MICROWAVE THEORY AND TECHNIQUES, Vol.55, Issue: 6, Part: 2, Jun. 2007, pp. 1382-1389. (8 pages)

M. Helaoui, S. Boumaiza, and F. M. Ghannouchi, “A New Part-Time LINC Architecture to Boost the Efficiency of WiMAX Up-Link Transmitters”, IEEE Trans. MTT, Vol.55, Issue: 2, Feb. 2007, pp. 248-253. (6 pages)

T. Liu, S. Boumaiza, A. B. Sesay, F. M. Ghannouchi, “Quantitative Measurements of Memory Effects in Wideband RF Power Amplifiers Driven by Modulated Signals”, IEEE Microwave and Wireless Components Letters, Vol.17, Jan. 2007, pp. 79-81. (3 pages)

Conference Papers/Presentation

Marie Claude Fares. Nizar Messaoudi, S. Boumaiza, J. Wood, “400-Watt Doherty Amplifier Linearization using Optimized Memory Polynomials Predistorter”, IEEE 71st ARFTG Microwave Measurement Symposium, Tempe, AZ, Nov. 26-30, 2007. (4 pages)

F. Hassam, S. Boumaiza, “WCDMA/WIMAX Dual-Band Bandpass Filter Design Using Frequency Transformation and Circuit Conversion”, IEEE International NEWCAS conference (IEEE-NEWCAS 2007). (4 pages)

Taijun Liu, S. Boumaiza, and Fadhel M. Ghannouchi, “An Integrated Nonlinear Behavior Modeling System for RF Power Amplifiers/Transmitters”, IEEE 71st ARFTG Microwave Measurement Symposium, Tempe, AZ, Nov. 26-30, 2007. (4 pages)

M. Helaoui, S. Boumaiza, A. Ghazel and F. M. Ghannouchi, “On the Dynamic Range Improvement and Robustness against Branch Imbalance of Mode-Multiplexing LINC Amplifiers”, IEEE International European Microwave Conference (EuMW’2007), Munich, October 2007.

Han Gil Bae, Renato Negra, S. Boumaiza, Fadhel M. Ghannouchi, “High-efficiency GaN class-E power amplifier with compact harmonic-suppression network”, IEEE International European Microwave Conference (EuMW’2007), Munich, October 2007.

O. Hammi, S. Boumaiza, B. Vassilakis, F. M. Ghannouchi, “On the Effects of the Average Power of Training Sequences Used to Synthesize Memory Digital Predistorters in WCDMA Transmitters”, IEEE International European Microwave Conference (EuMW’2007), Munich, October 2007.

Taijun Liu, Yan Ye, Xingbin Zeng, S. Boumaiza, Jiaming He, “Characterization and Modeling of Wideband Wireless Transceivers”, The 3rd International Conference on Wireless Communications, Networking and Mobile

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Computing (WiCOM 2007), pp.688-691, September 2007, Shanghai, China.

Taijun Liu, Yan Ye, S. Boumaiza, Xingbin Zeng, Jiaming He, Abu B. Sesay, and Fadhel M. Ghannouchi, Hammerstein-Like Predistortion Techniques for Wideband Wireless Power Amplifier Linearization, IEEE 2007 International Symposium on Microwave, Antenna, Propagation and EMC Technologies For Wireless Communications (MAPE 2007), pp.415-418, Aug.14-16, 2007, Hangzhou, China.

Taijun Liu, Yan Ye, S. Boumaiza, Xingbin Zeng, Jiaming He, Abu B. Sesay, and Fadhel M. Ghannouchi, Accurate Validation Methods for Dynamic Nonlinear Behavioral Models of Wideband RF Power Amplifiers Using Memoryless Predistortion Techniques, IEEE 2007 International Symposium on Microwave, Antenna, Propagation and EMC Technologies For Wireless Communications (MAPE 2007), pp.358-361, Aug.14-16, 2007, Hangzhou, China.

T. Liu, Y. Ye, S. Boumaiza, and F. M. Ghannouchi, "Dynamic Behavioral Models for Wideband Wireless Transmitters Stimulated by Complex Signals Using Neural Networks," Fourth International Symposium on Neural Networks (ISSN 2007), Nanjing, China, June 2007, pp. 582-591.

R. Negra, T. D. Chu, S. Boumaiza, G. M. Hegazi, and F. M. Ghannouchi, “Switch-based GaN HEMT Model Suitable for Highly-efficient RF power Amplifier Design”, IEEE MTT-S International Microwave Symposium (IMS’2007), Honolulu, Hawaii, June 2007, pp 795-798

Taijun Liu, Yan Ye, Xingbin Zeng, S. Boumaiza, Jiaming He, and Fadhel M. Ghannouchi, “Spectral Methods for Accurate Identification and Quantification of Memory Effects of Wideband RF Power Amplifiers”, 2007 5th International Conference on Microwave and Millimeter Wave Technology, April 19-21 2007, pp.790-793, Guilin, China

Taijun Liu, Yan Ye, Xingbin Zeng, S. Boumaiza, Jiaming He, and Fadhel M. Ghannouchi, “Memory Effect Pre-compensation for Wideband RF Power Amplifiers Using FIR-Based Weak Nonlinear Filters”, 2007 5th International Conference on Microwave and Millimeter Wave Technology, April 19-21 2007, pp.783-786, Guilin, China.

Oualid Hammi, S. Boumaiza, Bill Vassilakis, and Fadhel M. Ghannouchi, “New Digital Predistorter Architecture with Normalization Gain Control for Highly Non Linear Power Amplifiers”, IEEE International Midwest Symposium on Circuits and Systems (MWSCAS 2007),

S. A. Bassam, S. Boumaiza and F. M. Ghannouchi, “Study of the Hardware Imperfection and Channel Effects on the Antenna Selection Algorithms in MIMO Systems”, IEEE Canadian Conference on Electrical and Computer Engineering, Vancouver, BC, Canada, April 2007, on CDROM

N. Messaoudi, O. Hammi, S. Boumaiza and F. M. Ghannouchi, “A Comparative Study of Power Amplifier’s Sensitivity to Mismatched Load: Single Branch vs. Doherty Architectures”, IEEE Canadian Conference on Electrical and Computer Engineering, Vancouver, BC, Canada, April 2007. on CDROM

O. Hammi, S. Boumaiza and F. M. Ghannouchi, “Multi-Branch Polynomial Model of RF Power Amplifiers with Embedded Average Power Dependency”, IEEE Canadian Conference on Electrical and Computer Engineering, Vancouver, BC, Canada, April 2007. on CDROM

Patents

T. Liu, S. Boumaiza, and F. M. Ghannouchi, “LBG Nonlinear Behavioral Model for Characterizing and Pre-compensating Broadband Communication Systems”, Patent filled December 2007.

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Grants

Dr. Boumaiza’s EmRG research program is financially supported by federal and provincial granting agencies. The group was awarded the following grants:

1. Leader Opportunity Fund Infrastructure Project, from the Canadian Foundation for Innovation, that aims at the acquisition of Rapid Prototyping and Development Facility for RF/Digital Radio Systems.

2. Research Tools and Instruments (RTI) Grant, from the Natural Sciences and Engineering Council (NSERC) for the acquisition of a Modular semiconductor parameter analyzer

Graduate Students Distinction

The two graduate students working with Dr. Boumaiza, M. Helaoui (PhD) and H. G. Bae (M.Sc.) were ranked 2nd and 4th, respectively, in the third High Efficiency Power Amplifier Competition, which took place as part of the International Microwave Symposium in 2007. Source IEEE Microwave Magazine, Feb. 2008

Students

PhD Students:

Mohamed Helaoui, Thesis Subject: Modified LINC Transmitters for OFDM Radios, Recipient of iCore International Student Award

Sayed Aidan Bassam, Thesis Subject: MIMO Transceivers for 4G Wireless Communication Systems

Walid Saber El Deeb, Thesis Subject: Design of 4G Multiband and Multi-Standards Receivers. Recipient of International graduate scholarship from the Egyptian Government.

MSc Students:

Dylan Bespalko, Thesis Subject: Design Automation of Dual Band Radio Frequency Power Amplifier. Recipient of APEGGA Gold Medal Award and PGS M NSERC Scholarship.

Han Bae Gil, Thesis Subject: Design of High Efficiency Class E amplifier using GaN transistorGraduated in December 2007

Henry Lai, Thesis Subject: Design of Base Band Processor of a MIMO WIMAX Transceiver in FPGA Platform. Recipient of CGS M NSERC Scholarship.

Marie-Claude Fares, Thesis Subject: Nonlinear Behavioral Modeling of Broadband Transmitters. Recipient of PGS M NSERC Scholarship

Nizar Messaoudi, Thesis Subject: Design of High Efficiency Power Amplifiers using Load Modulation Technique. Recipient of Queen Elizabeth II Graduate Scholarship.

Slim Boumaiza can be reached via: Phone: 519-888-4567 Extension 37017

Email: sboumaiz@ecemail.uwaterloo.ca

Sujeet K. Chaudhuri, Professor, is a well-known authority in integrated photonic and numerical electromagnetics. He has made significant contributions to photonics and numerical electromagnetics, particularly in FDTD and hybrid FD-BPM methods. He has held NSERC research grants continuously since 1978. Over these years, he has supervised/ co-supervised many graduate students including a NSERC Doctoral Prize winner (Vien Van), mentored many highly successful research colleagues (Safavi-Naeini, W-P Huang, Majedi), and have led many major collaborative

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research initiatives (Ericsson CWC, Nortel Networks Inst., major CFI centers). In addition, he has provided academic and professional leadership as a Department Chair, Faculty Dean, CCPE/PEO council member and NCDEAS chair over the past 14 years. Throughout this period, he has maintained his personal research activities at the fundamental and applied level with his graduate students. In 2004, he was installed as the O’Donovan Research (endowed).

Research Projects

1. Rigorous Formulation for Electromagnetic Plane Wave Scattering from a General Shaped-Groove in a Perfectly Conducting Plane.

Near-field manipulations and waveform design of em scattering from open groove cavities, slits, or aperture is becoming important in many design analyses for nano- fabrication based terahertz and optical technology applications. In the above work, we present for the first time, a rigorous analytically based series formulation of the scattered fields from a single general shaped groove. The method has become the foundation block for the modeling and design of multiple general-shaped grooves, i.e., general-shaped finite gratings.

2. Polarization and Thickness Dependent

Guiding in the Photonic Crystal Slab Waveguide

Modal propagation (TE-like, TM-like), inside the PC slab waveguides, is of great interest and importance in many integrated silicon-photonic devices. We have numerically demonstrated the impact of the thickness on the modal behavior of the polarization dependent wave propagation in the PC slab waveguides. By realizing simultaneous lossless TE-like, TM-like propagation we have opened the doors for design of novel integrated polarization

processing devices like polarization beam splitters and mode convertors. 3. A Scalable 1 x N Optical MEMS Switch

Architecture Utilizing a Microassembled Rotating Micromirror

We have demonstrated a novel design and the fabrication of a 1 x N digital optical MEMS switch based on a 2-D micromirror assembled on a micromotor. The measured insertion loss of the switch is 1.04 dB with a maximum switching time of 24 ms. The switch fabric has a large number of output ports and a uniform coupling loss over all output channels, rendering signal equalization unnecessary. 4. Gaussian Beam Based Hybrid Method for

Unbounded Wave Structures

In this work a fast hybrid method which is a combination of Gabor expansion, GBT and FDTD is formulated and validated. The main focus has been the hybridization of the above mentioned methods in order to obtain a scheme which can be used model and unbounded wave structures that are large in terms of the operating wavelength. This is an important and practical design tool, meeting the needs of the current optical packaging/inter-connect related challenges. 5. Centre for Intelligent Antennas and Radio

Systems (CIARS)

CIARS is the culmination of our joint efforts over the past five years, resulting in a research infrastructure support of $12.5 M (CFI-$5M, OIT-$5M, Others-$2.5M). The main objective of this project is to develop an extensive state-of-the-art electromagnetic radiation and radio communication system test and characterization facility to perform research on innovative radio/antenna and artificial material technologies for future generation

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information systems and sensor networks. The new infrastructure will consist of: 1) Electromagnetic radiation test chamber including conventional far-field, all 3 types of near-field measurement and diagnosis test setup, and EMC (Electromagnetic Compatibility) test capability in the same chamber, 2) Ultra broadband signal and circuit (integrated and hybrid) characterization system, 3) Highly flexible radio system physical-layer characterization system, 4) Wireless Mesh Network(WMN) donated by Nortel Networks that will provide a realistic environment to test the developed algorithms and antenna structures, and 5) High precision rapid prototyping facility for RF/microwave multi-layer circuits. The new facility, being developed over the next two years, will house all required test equipment for the antenna, integrated front-end circuits, and "physical layer" design and characterization that cover the broadest range of frequency (MHz to THz). All infrastructure will be located within specialized laboratory facilities at the University of Waterloo. He plans to use the proposed infrastructure to validate novel numerical algorithms and to investigate new RF-photonic integrated circuits and innovative applications of superconducting thin films in microwave devices. This research paves the way for incorporating our most recent findings in the above areas into future integrated intelligent radio technologies.

Journal Publications

Elnaggar, M.S., Chaudhuri, S.K., Safavi-Naeini, S., “Multi-Polarization Dimensionality of Multi-Antenna Systems” submitted to IEEE Transactions on Antennas and Propagation, Oct., 2007, 22 manuscript pages.

Salehi, H, Chaudhuri, S.K., Mansour, R.R., “Anisotropic Left-Handed Slab Waveguide: Physics and Device Applications”, accepted in Advances in

OptoElectronics, Hindawi On-line Journal, Oct., 2007, 23 pages. Rohani, A, Chaudhuri, S.K., Safavi-Naeini, S., “Gaussian Beam Based Hybrid Method for Unbounded Wave Structures”, Submitted to IEEE Transactions on Antennas and Propagation, Sept., 2007, 9 journal pages.

Coutts, G.M., Mansour, R.R., Chaudhuri, S.K., “MEMS Reconfigurable Frequency Selective Surfaces and EBG Structures Monolithically Integrated on a Flexible Substrate”, submitted to IEEE Transactions on Microwave Theory and Techniques, Aug., 2007, 23 manuscript pages.

Elnaggar, M.S., Safavi-Naeini, S., Chaudhuri, S.K., “A Power-Independent Dimensionality Metric for Multi-Antenna Systems”, submitted to IEEE Transactions on Wireless Technology, Aug., 2007, 13 manuscript pages.

Bayat, K., Chaudhuri, S.K., Safavi-Naeini, S., “Polarization and Thickness Dependent Guiding in the Photonic Crystal Slab Waveguide” Optics Express, Optical Soc. of America Jour., Vol. 15 Issue 13, June 2007, pp. 8391- 8400. Basha, M.A., Chaudhuri, S.K., Safavi-Naeini, S, “A Generalized Formulation for Electromagnetic Scattering from Multiple Arbitray Shaped Grooves in Perfect Conducting Plane”, submitted to Journal of Optical Society of America A (JOSA-A), April, 2007, 24 manuscript pages.

Basha, M.A., Chaudhuri, S.K., Safavi-Naeini, S., Eom, H-J., “Rigorous Formulation for Electromagnetic Plane Wave Scattering from a General Shaped-Groove in a Perfectly Conducting Plane”, Journal Optical Society of America (JOSA-A), Vol. 24, No.6, March 2007.

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Basha, M.A., Dechev, N., Safavi-Naeini, S., Chaudhuri, S.K., “A Scalable 1 x N Optical MEMS Switch Architecture Utilizing a Microassembled Rotating Micromirror”, IEEE Journal of Selected Topics in Quantum Electronics, Vol. 13, No.2, Mar/Apr., 2007, pp. 336-347.

Students

PhD Students

Bayat, K., Thesis Subject: PBG Based PC Slab Waveguides for Optical/THz Applications.

Basha, M., Thesis Subject: Optical Switches: Theory, Design & Fab of a New Architecture.

Coutts, G.M., Thesis Subject: Miniature MEMS-Based Adaptive Antennas on Flexible Substrate.

Salehi, H.R., Thesis Subject: Electromagnetic Left-Handed Media Physics and Device Application.

Sujeet K. Chaudhuri can be reached via: Phone: 519-888-4567 Extension 32843 Email: S.Chaudhuri@ece.uwaterloo.ca

A. Hamed Majedi, Assistant Professor, received B.Sc. degree in Electrical Engineering with a major in microwave engineering from K. N. Toosi University of Technology, Tehran, Iran in 1994 and M.Sc. in Electrical Engineering with a major in photonics from Amir Kabir University of Technology, Tehran, Iran in 1996. In 1998, he joined the Electrical and Computer Engineering (ECE) Department, at the University of Waterloo, ON, Canada, and obtained his PhD with distinction on December 2001. His PhD thesis investigated the optical-microwave interaction in superconducting transmission lines for optoelectronic applications. After 10 months being

as a Postdoctoral Fellow, he joined the Institute for Quantum Computing (IQC), cross-appointed with the ECE dept., as a Research Assistant Professor and in 2005 became an assistant professor in ECE cross-appointed to IQC and dept. of Physics. He is conducting Integrated Quantum Optoelectronics Lab (IQOL) as the first laboratory in faculty of engineering supported by IQC. His main research interests and activities include superconducting microwave/photonic devices, THz optoelectronics, superconducting and photonic quantum devices for quantum communication and metrology, quantum nano-electrodynamics, plasmonics and metamaterials.

Research Projects

1. Superconducting Optoelectronics

Quantum electromagnetic characteristics of superconductors at low temperatures can be employed for performing ultra-low-noise/ultra-low-power and ultra-fast/high-frequency optoelectronics such as detection, mixing, amplification and switching. Pushing the sensitivity of the superconducting optoelectronic devices to single photon level such as single-photon detector not only introduce the ultimate performance of such devices but also operate in a quantum regime highly on demand for quantum information processors. IQOL is currently pursuing three projects in the superconducting optoelectronics.

a. Superconducting Nanowire Single Photon Detector

Today’s state-of-the-art Single Photon Detectors at the telecom wavelengths use Avalanche Photo Diodes (APDs) and NbN or Nb nanowire structures, commonly known as SNSPD (Superconducting Nanowire Single Photon Detector). Merits of various single photon detectors are generally compared to each other based on their counting rate, dark count, system quantum efficiency, ability to resolve photon number, operation condition and complexity in

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readout electronics. The NbN SNSPD operating at liquid Helium temperatures biased very close to its critical current has nominally 20% to 30% detection efficiency, Hundred of MHz counting rate and few KHz dark counts at the telecom wavelengths. Due to ultra low dark count rate and potentially high counting rate approaching hundreds of MHz of the NbN SNSPD, there is a rapidly growing interest to employ them in several applications especially in quantum optics, quantum communications and ultra-low-power spectroscopy and imaging.

We develop various packaging techniques for SNSPD, including DC biasing schemes, readout electronics and fiber optical coupling to characterize

them at 4K temperature. The above figure shows the SEM image of the SNSPD fabricated by Superconducting Nanotechnology Inc. in Russia and the IQOL packaging. This figure shows the fiber-coupled SNSPD in ST-500 Cryostat and part of the readout electronics. We are able to achieve single photon optical detection at 1310 nm and 1550 nm. The results of our experiments have been submitted to the Journal of Modern Optics and 2008 Applied Superconductivity Conference. This project is done by Zhizhong Yan, Jean-Luc Orgiazzi and Mohsen K. Akhlaghi.

(Left) (a) SEM image of the active area; (b) The package with cover installed; (c) The package when the cover is open; (d) The microscope infrared image of the SNSPD active area for the optical alignment.

(Left Below) STWPD Schematics 

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b. Superconducting Traveling-Wave

Photodetector

The theory, analysis and design of Superconducting Traveling-Wave PhotoDetector (STWPD) have been developed. The optical propagation analysis, optical-electrical interaction and the electrical signal propagation in STWPD has been carried out successfully. The schematic of STWPD is shown in the above figure. The STWPD operation is as follows. Light is guided through a multilayer waveguide which consists of one or more superconductive layers. As light propagates down the waveguide, it is attenuated due to absorption by the superconductive layer(s). While light is absorbed at each point along the optical waveguide, electrical voltage is generated locally due to the bias current together with the modulation of the kinetic inductance and normal resistance caused by Cooper pair breaking process. The amplitude of these local voltage sources depend on the amount of optical power being absorbed at each point. Since light is attenuated exponentially down the optical waveguide, the amplitude of the local voltage sources decreases exponentially as well. In fact, as a result of the propagation and absorption of light through the optical waveguide and its local conversion into electrical voltage, the superconductive film acts like a distributed voltage source. In order to accumulate the responses of these optically driven distributed voltage sources, a microwave transmission line is required. Interestingly, the superconductive layer can be simultaneously designed to serve as a transmission line, which collects the contribution of distributed voltage sources and delivers the photogenerated electrical power to the load. So while the light is attenuated down the waveguide, the electrical signal is built-up along the transmission line. The results of this project have been submitted. This project is done by Behnood G. Ghamsari and Hamed Majedi.

c. Tl2212 ( y222 OCaCuBaTl ) Microwave

Photonic Devices

Through collaboration with Prof. C.J. Stevens of Faculty of Engineering Science at Oxford University, we fabricated several Tl2212 high-frequency structures, including CPW, micron-size meanderline in CPW bed and CPW-based traveling-wave photodetectors. Tl2212 is a High-Temperature Superconductor (HTS) with a thin film critical temperature around 110K and ultrafast picosecond photoresponse. The characterization of our devices has been started recently and the results of our first phase of experiments is planned to be presented in 2008 Applied Superconductivity Conference. The project is done by Haig Atikian (spending 6 months in Oxford) and Behnood G. Ghamsari.

2. Superconducting mm-Wave & THz Devices

Ultra-low loss and ultra-low dispersion characteristics of Superconducting Transmission Lines (STL) can be used to develop high performance mm-wave and THz devices where low noise and high sensitivity to external stimuli are on demand. Combination of STL and Josephson junction based electronics make them a potential platform to develop mm-wave and THz integrated circuits and integrated mm-wave and THz photonic devices. IQOL is currently working on two projects in this area.

a. Superconducting Periodic Transmission Line

Linear and nonlinear microwave signal propagation has been studied in a periodic superconducting transmission line composed of alternative STL and either normal TL (S-N) or dielectric gap (S-I). The frequency response analysis using an analytical method based on the combination of ABCD matrix and Floquet’s theorem is developed. We derive the dispersion and impedance equations for both structures, S-N and S-I TLs, with infinite and finite length. Dispersion and impedance equations are solved numerically under various boundary

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conditions in order to find the propagation characteristics such as complex propagation constant and group velocity. Band gap formation in S-I TL is investigated for its potential applications in the design of passive filters and resonators. The role of kinetic inductance nonlinearity in band gap engineering of the SI-TL is studied for its potential benefit to tune the resonant frequency and the filtering properties. This project is done by Hamid Reza Mohebbi.

b. Discrete Josephson Junction Transmission Line

We study the nonlinear wave propagation in a Discrete Josephson Junction Transmission Line (DJJTL). DJJTL consists of a finite number of unit cells each including a segment of superconducting transmission line with a single or stack of N identical lumped element Josephson junctions (JJs). Employing a generalized RCSJ model of JJs, accounting for the nonlinear inductance and resistance of the single or stack of N identical JJs, the nonlinear wave propagation in the DJJTL is investigated. As the governing nonlinear wave propagation is a system of nonlinear partial differential equations with mixed boundary conditions, the method of Finite Difference Time Domain (FDTD) is used to solve the equations numerically. Two regimes of wave propagation are found in the structure. By this tool, the behavior of wave propagation along the DJJTL can be monitored in both time and space domains across each unit cell. We will investigate the various operating conditions to acquire microwave traveling-wave devices such as Josephson oscillators, mixers and amplifiers. This project is done by Hamid Reza Mohebbi.

3. Plasmonics

Coupling of Electromagnetic waves to the surface plasma oscillation is referred to as surface plasmon polariton (SPP). The electromagnetic waves associated with the SPPs have the peculiar feature that decay exponentially away from the surface of

plasma, thereby are called surface waves. Since the energy of surface waves is confined in the vicinity of the plasma surface, they might be guided by the SPP and serve as guided modes. Guided wave structures that rely on this mechanism for guiding of electromagnetic radiation are called plasmonic waveguides. Metals and semiconductors behave as electron plasmas at visible and near infra red region of spectrum. Confinement of optical power within sub-wavelength region by plasmonic waveguides, make them an attractive choice for the integrated optics and nanophotonic applications. We have done three projects last year in Plasmonics.

a. Supermodes in Coupled Dielectric-Plasmonic Slab Waveguides

Some applications in nanophotonics and integrated optical devices demand the proximity of photonic structures with plasmonic waveguides in which the field distribution analysis is a key issue. The field distribution in these complex structures is called supermode. We have carried out supermode analysis for multilayer structures resulted by proximity of a plasmonic waveguide to a dielectric slab waveguide. Supermodes of a multilayer slab waveguide consisted of dielectrics and metals are solved by means of Transfer Matrix Method (TMM) and Cauchy Integral Method (CIM). This project is done by Behnood G. Ghamsari.

b. THz Plasmonic Transmission Line

We develop a transmission line model for a THz surface and parallel plate waveguides based on the possibility of having low loss quasi-TEM propagation in these structures. Our transmission line model shows how to determine voltage and current waves along with characteristic impedance and propagation constant of these structures. This project is done by Behnood G. Ghamsari.

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c. Superconducting THz and Optical Plasmonic Waveguides

Superconductors act an ultra-low loss plasma medium bellow their gap frequencies (typically in THz region) and lossy plasma medium between their gap frequencies and plasma frequencies. We have studied the possibility of creating superconducting multilayer waveguides in mm-wave, THz and optical regions using combinations of dielectrics and superconducting layers using analytical solutions of Maxwell’s equations coupled to either Two-Fluid model or BCS theory of superconductivity. This project is done by Hamed Majedi.

d. Superconducting Circuit Quantum Electrodynamics

Recent progress in Circuit Cavity Quantum Electrodynamics (CQED) and solid state quantum information processors stimulates IQOL to take up a new project to fundamentally investigate the quantum electrodynamic properties of basic superconducting electrical circuits and transmission lines. This project has been commenced on September 2007 and the result of the first phase of our project will be presented in Applied Superconductivity Conference in Aug. 2008. Jeyran Amirloo is working on this project.  

Journal Publications

Z. Yan, A. H. Majedi, and S. Safavi-Naeini, "Physical Modeling of Hot-Electron Superconducting Single Phonton Detectors", accepted for publication in IEEE Transactions on Applied Superconductivity, Vol. 17, No. 3, pp.3789-3794, September 2007.

A. H. Majedi, "Multilayer Josephson Junctions as Quantum Well Structure", IEEE Transactions on Applied Superconductivity, Vol. 17, No. 2, pp. 617-620, June 2007.

B.G. Ghamsari, A. H. Majedi, "Rigorous Analysis of Superconducting Multilayer Optical Waveguides",IEEE Transactions on Applied Superconductivity, Vol. 17, No. 2, pp.590-593, June 2007.

H. Salehi, R.R. Mansour, and A.H. Majedi, "Nonlinear Josephson left-handed transmission lines", IET Microwaves, Antennas & Propagation,Volume 1, Issue 1, p. 69-72, February 2007.

Conference Papers/Presentation

A. H. Majedi, Zhzihong Yan, Jean-Luc Orgiazzi, “Characterization of NbN Nanowire Superconducting Single Photon Optical Detectors at Telecom Wavelength”, Single Photon Workshop 2007, INRIM, Torino, Italy, Sept. 2007. (Invited Talk).

H.R. Mohebbi, A. H. Majedi ,"Superconducting transmission line periodically-loaded by a normal transmission line and dielectric gap", EMTS 2007 - International URSI Commission B - Electromagnetic Theory Symposium , Ottawa, ON, Canada, July 2007.

H.R. Mohebbi, A. H. Majedi , "Characteristics of Superconducting Transmission Line with Metal Grating for Microwave Circuits", ISSSE 2007, IEEE, International Symposium on Signals, Systems and Electronics, pp. 213-216, Montreal, QC, Canada, July 2007.

A. H. Majedi," Recent Advances and Future Prospects for Superconducting Metamaterials ", EMTS 2007 - International URSI Commission B - Electromagnetic Theory Symposium , Ottawa, ON, Canada, July 2007. (Invited Talk)

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Students

PhD Students

Behnood G. Ghamsari, Thesis Subject: Traveling-Wave Superconducting Optoelectronic Devices, Interaction of light with superconducting weak links and junctions

Hamid Reza Mohebbi, Thesis Subject: mm-wave and THz Josephson-Junction based superconducting devices.

Mohsen K. Akhlaghi, Thesis Subject: Optoelectronic Characterization and Modeling of Superconducting Nanowire Single Photon Detectors (SNSPDs)

Zhizhong Yan, Thesis Subject: Packaging, Optical and High-frequency characterization of Superconducting Nanowire Single Photon Detectors (SNSPDs)

MSc Students

Haig. A. Atikian, Thesis Subject: Fabrication and microwave photonic characterization of Tl2212 optoelectronic devices

Jean-Luc Orgiazzi, Thesis Subject: Packaging, characterization and thermal analysis of Superconducting Nanowire Single Photon Detectors (SNSPDs)

Jeyran Amirloo, Thesis Subject: Circuit Quantum Electrodynamics

A. Hamed Majedi can be reached via:

Phone: 519-888-4567 Extension 37443 Email: ahmajedi@maxwell.uwaterloo.ca

 

 

 

Rafaat Mansour, Professor, received his Ph.D. degree in Electrical Engineering from the University Of Waterloo, Ontario, Canada in 1986. He Joined COM DEV, Cambridge, Ontario, Canada, in November 1986 where he held several key positions at COM DEV's Corporate R&D Department from 1986-1999. In December 1999, he joined the University of Waterloo as a Professor. He holds an NSERC / COM DEV Industrial Research Chair on RF Engineering at the University of Waterloo.

Throughout his industrial and academic career, Dr. Mansour has been able to successfully apply theoretical solutions to practical problems to address issues of key interest to the RF and microwave engineering community. Dr. Mansour holds 29 US and Canadian patents to his credit (25 awarded and 4 pending). He has been a pioneer in employing emerging materials and technologies such as high temperature superconductor and micro-electro-mechanical system (MEMS) to build novel RF devices with unprecedented performance. Dr. Mansour has more than 200 refereed publications. He is a co-author of a 20-chapter Wiley book Published in July 2007, and has contributed 4 chapters to other two books. He has received several Best Paper Awards and outstanding research performance awards from both COM DEV and the University of Waterloo. Dr. Mansour’s excellence in research has been recognized internationally through Fellowship in the IEEE. He is a registered Professional Engineer in Ontario and is a Fellow of the Engineering Institute of Canada (EIC).

Dr. Mansour is the founder of the Center for Integrated RF Engineering (CIRFE) that was established in the year 2000 at the University of Waterloo. The CIRFE Center currently has a research group consisting of 25 Ph.D and M.Sc graduate students, research engineers and postdoctoral fellows. The focus of the CIRFE Center’s research activities is on emerging RF technologies including RF Micro-Electro-

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Mechanical Systems (RF-MEMS), reconfigurable and intelligent front end subsystems, advanced filters & multiplexers, computer-aided tuning, superconductivity, integrated MEMS/CMOS circuits and wireless sensors. The uniqueness of the CIRFE Center lies in the ability to integrate various RF technologies and in its wide range of capabilities, which include research, development, modeling, design, fabrication, packaging and test.

CIRFE houses a new state-of-the-art RF test and characterization laboratory and a clean room. The CIRFE clean room includes plasma enhanced chemical vapor deposition (PECVD) system, reactive ion etching (RIE) system, e-beam evaporator/ dc-sputtering system, a critical point dryer system, electroplating system, chemical mechanical planarization (CMP) System, mask aligner and all necessary wet etching equipment. The laboratory houses several wafer probers with dc and RF probing capabilities, RF test equipment, flip-chip bonder, ball bonder and thermal cycling chamber, 16-channel MEMS driver station and laser micromachining system. A detailed description of the CIRFE facility is given at www.cirfe.ca

Research Projects

1. RF MEMS Devices and Components

The Micro-Electro-Mechanical System (MEMS) technology has the potential of replacing many Radio Frequency (RF) components such as switches, vararctors, phase shifters, and filters used in today’s communication systems. In many cases, such RF MEMS components would not only reduce substantially the size, weight and power consumption, but also promise superior performance to that of current technologies. RF MEMS will also play a major role in the development of RF intelligent systems. These systems can intelligently adapt in real time to optimize their performance to

operational demands or environmental changes. The adaptive capabilities would enable new functionality and system capability that are not possible with current technologies such as a micro system on a chip that is able to sense, act and communicate. It would also enable system architectures with unprecedented agility. Over the past few years, the CIRFE center has been involved in the development of RF switches, switch matrices, varactors and phase shifters.

2. Integrated RF MEMS/CMOS Circuits

The fabrication of MEMS devices in commercially available CMOS technology, with a minimum feature size of a few hundred nanometers, can push MEMS technology to higher integration. It improves performance of RF integrated circuits (RFICs) and results in the elimination of bulky off-chip components. A process for post-processing of CMOS chips to create MEMS devices within the CMOS chip has been developed in the CIRFE clean room for CMOS 0.35 μm. and CMOS 0.18 μm technologies. The process allows the creation of MEMS varactors and actuators with both vertical and lateral movement within the CMOS chip. Several interdigital and parallel- plate MEMS variable capacitors have been developed. A CMOS tunable filters with a relatively high–Q value has been demonstrated using this concept. An integrated LNA with high Q tunable MEMS-based matching network in CMOS 0.18 μm has been also demonstrated.

3. High-Q MEMS-Based Tunable Filters Tunable filters are needed in communication systems to facilitate efficient utilization of the available frequency spectrum and for interference elimination. They are also in demand in advanced systems concepts that self-adapt to operational requirements. The focus of the research will be on the development of miniature high-Q reconfigurable RF filters and switched filter banks. The objective

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of this project is to use MEMS technology for the realization of miniature High-Q tunable filters. Novel techniques are being developed to maintain a constant bandwidth over a wide tuning range with a minimum number of tuning elements. Monolithic MEMS integration with planar filters and hybrid MEMS integration with 3D-filters such as ridge waveguide and dielectric resonator filters are being considered under this project. The project also deals with the development of high power MEMS-based impedance tuners for matching antennas to power amplifiers

4. Reconfigurable Impedance Matching

Networks

Intelligent RF front-ends that can support multi-band functionality have an important role in communication systems. In these systems, there is often an impedance mismatch between the building blocks such as an antenna and a power amplifier due to the operation in different frequency bands or varying operational conditions. A tunable impedance matching network with a wide impedance coverage, bandwidth and low insertion loss is required within these RF front-ends to ensure an optimum power transfer between the blocks. In addition to impedance matching, reconfigurable matching networks capable of producing a multitude of impedance points are necessary for use in characterization of power or low noise transistors. In this case the matching network is used as an impedance tuner to manipulate the impedance conditions under which the DUT or transistor is tested. A number of MEMS-based reconfigurable impedance matching networks and impedance tuners have been demonstrated both at low-frequency and at millimeter-wave frequencies. 5. MEMS on Flexible Substrate

A novel MEMS process is developed to fabricate large numbers of high-performance MEMS devices monolithically integrated onto a rigid-flex organic

substrate using low-temperature processes. The rigid-flex substrate is all dielectric, which is amenable to low-loss electromagnetic structures. The substrate provides mechanical support to the MEMS devices while maintaining overall flexibility. The newly developed process is used to fabricate a MEMS reconfigurable frequency-selective surface (FSS). A practical bias network is incorporated into the structure design to ensure that all devices are actuated simultaneously. A detailed parametric sensitivity analysis establishes the robustness of the FSS design with respect to fabrication process variations. Reconfigurable FSS structures are fabricated and tested with good correlation between simulated and measured results. The newly developed MEMS process is also used to fabricate a reconfigurable electromagnetic-bandgap (EBG) structure. An EBG structure operating in the -band is fabricated and tested to verify the validity of the proposed concept. 6. MEMS-based Micro-power Generators

The design of embedded autonomous sensors requires the use of an onboard source of power. Micro-Power Generators (MPGs) can satisfy this requirement by harvesting energy from the environment and turning it to an electric power. These micro-generators can be used not only as a source of power but can also be used in conjunction with batteries to increase their lifetime. Energy harvesting can be efficiently implemented by mechanical energy conversion. Vibration energy conversion, on the other hand, can be realized by electrostatic, piezoelectric or electromagnetic transduction and can potentially used as a dc power source for low power CMOS transceivers. The focus of this project is to develop MEMS-based electromagnetic-type and electrostatic-type micro power generators. As these generators typically operate over a narrow frequency band, several techniques are being investigated to develop wide band micro energy harvesters that can be employed in variety of wireless sensor applications.

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7. Miniature Dielectric-Loaded Filters

The objective of this project is to develop highly miniature filters. Several novel dielectric resonator filters made from high K-ceramic substrate have been developed and experimentally demonstrated. The proposed filter structure combines the low cost production of combine filters with high-Q feature of traditional dielectric resonator filters. It also makes it easy to control the filter spurious performance. The project also deals with the development of dual-mode and triple-mode dielectric resonator filters as well as the development of multi-band filters.

8. Computer–Aided Tuning of Filters

As a result of manufacturing and material tolerances, filter tuning is an essential post-production process. Traditionally, filters have been tuned manually by skilled technologists. The tuning process is not only time consuming, but also expensive, particularly for high-order narrow-band filters with stringent requirements. It is a fact that almost all the filters for wireless base stations and satellite applications must be subjected to a post-production tuning process. For many technologists, the manual tuning process has been more of an art than a science. Therefore, the manual tuning of a complex filter and multiplexer structures is usually performed by well experienced technologists. The research focuses on the development of several algorithms for tuning of microwave filters. These algorithms bring science ( theoretical models) and art (artificial intelligence models) into one computer model that can efficiently and intelligently tune these filters CIRFE Researchers received the BEST PAPER AWARD in IEEE-IMS 2006 for the development of an intelligent algorithm for filter tuning.

9. Development of Multi-Channel Electrodes for Deep Brain Stimulation (DBS) Systems.

Deep Brain Stimulation (DBS) is a neural modulation therapy used to treat disorders such Parkinson’s disease, essential tremor and depression.

The therapy is well known for its high effectiveness and low-side effects. The current DBS system involves the use of an electrode implanted in the patient’s brain to provide a stream of electrical pulses to control the disorder. The current commercial DBS system mostly consists of a 4-channel stimulation electrode with no recording capability. The objective of this project is to develop a multi-channel electrode (up to 64 channels) with both stimulation and recording capabilities. The project also involves a detailed study of field interaction with neurons.

10. MEMS-based Nano Probing and Nano Instrumentations

We plan to introduce a new class of devices and instrumentation to the semiconductor, RF and other industries that leverage the myriad economic benefits of having integrated systems with both electrical and mechanical functionality. Examples are: a) multi-probe manipulators for electrical and mechanical characterization of devices and interconnects with unprecedented precision and stability performance, b) Arrays of scanning probe instruments that can achieve record throughputs in metrology and semiconductor materials (near-term), and form the basis for a revolutionary emerging technology for atomically precise manufacturing (long-term)

Journal Publications

M. Baker-Kassem and S. Fouladi and R. R. Mansour “Novel High-Q MEMS curled-plate variable capacitor fabricated in 0.35 μm CMOS technology”, IEEE Transactions on Microwave Theory and Techniques, 12 pages, accepted for publication in 2007 (will be published early 2008, see ieeexplore.ieee.org) .

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M. EL Sabbgah and R. R. Mansour, “Ultra wide band suppression band of surface waves using periodic microstrip-based structures”, IEEE Transactions on Microwave Theory and Techniques, 12 pages, accepted for publication in 2007 (will be published early 2008, see ieeexplore.ieee.org).

V. Miraftab and R. R. Mansour “Fully Automated RF/Microwave Filter Tuning by Extracting Human Experience Using Fuzzy Controllers”, IEEE Transactions on Circuits and Systems. 10 pages, accepted for publication in 2007 (will be published early 2008, see ieeexplore.ieee.org).

G. Coutts, R. R. Mansour and S. Chaudhuri “Microelectromechanical Systems Tunable Frequency-Selective Surfaces and Electromagnetic-Bandgap Structures on Rigid-Flex Substrates”. ”, IEEE Transactions on Microwave Theory and Techniques Accepted for publication in 2007 (will be published in 2008, see ieeexplore.ieee.org).

G. Coutts, R. R. Mansour and S. Chaudhuri “Analysis Technique for Frequency-Switchable and MEMS-Based Multi-Mode Parasitic Patch Arrays, IET Transactions”. Accepted for publication in 2007 (will be published early 2008, see ieeexplore.ieee.org). R. Zhang, and R. R. Mansour, “Low-Cost Dielectric-Resonator Filters with Improved Spurious Performance”, IEEE Transactions on Microwave Theory and Techniques, Vol 55, pp. 2168-2175, Oct 2007.

M. Daneshmand, W. D. Yan, and R. R. Mansour, “Thermally Actuated Multiport RF MEMS Switches and Their Performance in a Vacuumed Environment, IEEE Transactions on Microwave Theory and Techniques”, vol. 55, pp 1229-1236, June 007.

R. Zhang, and R. R. Mansour,” Novel Digital and Analogue Tunable Low Pass Filters”, Microwaves, Antennas & Propagation, IET, pp. 549-555, June 2007.

M. Daneshmand and R. R. Mansour, “Redundancy RF MEMS Multiport Switches and Switch Matrices”, IEEE/ASME Journal of Microelectromechanical Systems, vol, 16, pp. 296-303, April 2007.

H. Salehi, R. R. Mansour, and A.H. Majedi, “Nonlinear Josephson Left-handed Transmission Lines”, Microwaves, Antennas & Propagation, IET, pp.69 – 72, February 2007.

W. D. Yan, and R. R. Mansour, “Tunable Dielectric Resonator Bandpass Filter With Embedded MEMS Tuning Elements”, IEEE Transactions on Microwave Theory and Techniques vol. 55, pp 154-160, January 2007.

Refereed Conference Papers

R. Al-Dahleh, R. R. Mansour, “A Novel Warped-Beam Design that Enhances RF Performance of Capacitive MEMS Switches”, IEEE-MTT –IMS, pp. 1813 – 1816, June 2007.

W. D. Yan and R. R. Mansour, “Compact Tunable Bandstop Filter Integrated with Large Deflected Actuators”, IEEE-MTT –IMS, pp. 1611 – 1614, June 2007.

V. Miraftab, R. R. Mansour and M. Yu, “Moment Method Using Fuzzy Basis Functions”, IEEE-MTT –IMS, pp. 1999 – 2002, June 2007.

S. Fouladi, M. Bakri-Kassem, R. R. Mansour, “An Integrated Tunable Band-Pass Filter Using MEMS Parallel-Plate Variable Capacitors Implemented with 0.35ýým CMOS Technology”, IEEE-MTT –IMS, pp. 505-508, June 2007.

G. Coutts, R. R. Mansour and S. K. Chaudhuri, “A MEMS-Tunable Frequency-Selective Surface Monolithically Integrated on a Flexible Substrate”, IEEE-MTT –IMS, pp. 497-500, June 2007.

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S. Cogollos, R. J. Cameron, R. R. Mansour, M. Yu, and V. Boria, “Synthesis and Design Procedure for High Performance Waveguide Filters Based on Nonresonating Nodes”. IEEE-MTT –IMS, pp. 1297-1300, June 2007

B. Keats, R. R. Mansour and R.B. Gorbet, “Design and testing of thermally stable filter using Bimetal compensation”, IEEE-MTT –IMS, June 2007.

E. Chan , M. Daneshmand, R. R. Mansour and R. Ramer, ”Novel Beam Design for Compact RF MEMS Series Switches”, Asia Pacific Microwave Conference (APMC), December 2007.

N. Sarkar and R. R. Mansour “CMOS-MEMS Nanopositioners with Integrated Position Sensing and Digital Control”, CWMEMS 2007, August 2007. ( Received the Second place for BEST PAPER AWARD) S. Fouladi, M. Bakeri-Kassem, and R. R. Mansour, “CMOS-MEMS Post-Processing Technique Developed for Integrated RF MEMS Devices”, CWMEMS 2007, August 2007. M. Daneshmand and R. R. Mansour, “ A 3×3 RF MEMS Switch Matrix Integration”, CWMEMS 2007, August 2007.

P. Laforge and R. R. Mansour,” Integration of MEMS Devices and Superconducting Filters for High Q Tunable Filter Applications”, CWMEMS 2007, August 2007.

M.Bakeri-Kassem and R. R. Mansour,” A Parallel Plate MEMS Variable Capacitor with Vertical Thin Film Comb Actuators”, CWMEMS 2007, August 2007.

R. Al Dahleh and R. R. Mansour, ” Novel Warped-Beam Capacitive MEMS Switches”, CWMEMS 2007, August 2007. T. Oogarah and R. R. Mansour ‘Anodized Porous Anodic Alumina as a novel low cost MEMS

Material, CWMEMS 2007, August 2007.

Book Publication

Microwave Filters for Communication Systems, Fundamentals, Design and applications,” R, Cameron, C. Kudsia and R. R. Mansour (20 chapters). John Wiley July 2007.

Patents

R. R. Mansour and M. Daneshmand, “MEMS based RF components and a method of construction thereof”, US patent 7,292,125 issued November 6, 2007.

M. Daneshmand and R. R. Mansour,” Multi-Port Monolithic RF MEMS Switches and Switch Matrices” A full US patent application was filed in March 2007.

R. R. Mansour and R. Zhang” Dielectric resonators filters fabricated from dielectric substrates”, (A US Patent Pending).

G. Coutts, R.R. Mansour, S. Chaudhuri, and W. C. Tang, Reconfigurable RFID antenna. (A US Patent Pending)

Research Group

Bill Jolley (Lab Manager) - Responsible for operation of the CIRFE LAB facility.

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Dr. Mojgan Daneshmand (Post Doctoral Fellow) - MEMS switches and switch matrices.

Dr. Peter Basl (Post Doctoral Fellow) – Modeling of MEMS and RF circuits.

Dr. Rui Zhang (Post Doctoral Fellow) – Novel Miniature Filters.

Roger Grant (Clean Room Process Engineer) - MEMS fabrication processes.

Ph.D graduate students

Arash Fomani ( Ph.D graduate student) - Electrodes for deep brain stimulation and recording.

Brain Keats ( Ph.D graduate student) - Temperature compensation of high power filters.

Fengxi Huang (Ph.D graduate student) - High -Q micro-machined tunable filters.

Gorden Coutts ( Ph.D graduate student) - MEMS on flexible substrate

Maher Bakeri-Kassem ( Ph.D graduate student) - MEMS/CMOS variable capacitors

Mohamed Mahmoud ( Ph.D graduate student) - MEMS electrostatic micro-power generators.

Mostafa Soliman ( Ph.D graduate student) - MEMS electromagnetic micro-power generators.

Neil Sarkar ( Ph.D graduate student) - MEMS-based nano-probing and nano-instrumentation.

Nino Zahirovic ( Ph.D graduate student) - Intelligent RF MEMS/CMOS circuits.

Paul Laforge ( Ph.D graduate student) - MEMS-based tunable superconductor filters.

Reena Al Dahlah ( Ph.D graduate student) - MEMS phase shifters and integrated systems.

Salam Gobran ( Ph.D graduate student) - Cortical micro-electrodes for brain recording.

Sara Attar ( Ph.D graduate student) – Low temperature superconductor MEMS switches

Sepehr Forouzanfar (Ph.D graduate student) - Miniature MEMS-based mechanical filters.

Siamak Fouladi ( Ph.D graduate student) - CMOS/MEMS switches and tunable networks

Winter Yan (Ph.D graduate student) - High Q MEMS-based 3D tunable filters

M.Sc graduate students

Aviviere Telang (M.Sc graduate student) - Multipaction analysis of high power filters)

Mohammad Memarian (M.Sc graduate student) - Novel dielectric filter configurations

Sormeh Setoodeh (M.Sc graduate student) – Miniature superconductor filters.

Tania Oogarah (M.Sc graduate student) - Low cost MEMS fabrication processes.

Raafat Mansour can be reached via:

Phone: 519-888-4567 Extension 35780 Email: raafat.mansour@ece.uwaterloo.ca

www.cirfe.ca  

Omar Ramahi, Professor, received the BS degrees in Mathematics and Electrical and Computer Engineering (summa cum laude) from Oregon State University, Corvallis, OR. He received his M.S. and Ph.D. in Electrical and Computer Engineering from the University of Illinois at Urbana-Champaign. From 1990-1993, Dr. Ramahi held a visiting fellowship position at the University of Illinois at Urbana-Champaign. From 1993 to 2000, he worked at Digital Equipment Corporation (presently, HP), where he was member of the alpha server product development group. In August of 2000, he joined the faculty of the James Clark School of Engineering at

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the University of Maryland at College Park. At Maryland he was also a faculty member of the CALCE Electronic Products and Systems Center where he was the Director of the Electromagnetic Compatibility and Propagation Laboratory. Presently, he is the RIM/NSERC Industrial Research Associate Chair in the Electrical and Computer Engineering Department with cross-appointments in the Physics and Astronomy and Mechanical Engineering Departments. Dr. Ramahi was instrumental in developing computational techniques to solve a wide range of electromagnetic radiation problems in the fields of antennas, high-speed devices and circuits and EMI/EMC. His interests include experimental and computational EMI/EMC studies, high-speed devices and interconnects, biomedical applications of electromagnetics, novel optimization techniques, and interdisciplinary studies linking electromagnetic application to novel materials. Dr. Ramahi has over 170 refereed publications. Dr. Ramahi served as a consultant to several companies and was a co-founder of EMS-PLUS, LLC and Applied Electromagnetic Technology, LLC. Research Projects

1. Electromagnetic Bandgap Structures for Noise Mitigation on Printed Circuit Boards and for Reducing the Coupling between Antennas -

Unintentional electromagnetic energy is typically referred to as noise. This terminology is similar to the colloquial use of the word “noise” except for the frequency which is much higher. This unwanted

electromagnetic radiation or noise can propagate in complex ways and through various media. As an example, a cell phone, used on board an aircraft emits signals that can potentially affect the avionics instruments of the aircraft. Instruments used for medical diagnosis can be susceptible to electromagnetic interference to the point that the use of cell phones in certain locations in many clinics and hospitals is banned. A transistor used in a logic circuit switching from 1 to 0 or vice-a-versa creates a high frequency electromagnetic pulse, or, again, noise, that travels everywhere polluting the delicate electronic and electromagnetic system around it. These are but a few of the hundreds of types of noise that are becoming more prevalent and, in fact, if unchecked, can be detrimental to the operation of modern electronic devices. In our work, we are interested in understanding the electromagnetic noise propagation mechanism. More specifically, we are interested in developing novel techniques to keep unwanted electromagnetic signals in check by using electromagnetic bandgap structures. These structures are nothing but patches of copper with certain geometrical shapes that determine their operating frequency. By using these band gap structures, the shielding of noise is done practically at the source, thus eliminating expensive fixes that are typically introduced after the design of the printed boards or packages is completed. Electromagnetic band gap structures have also been proven effective in reducing the coupling between closely separated antennas. In our work, we are also interested in miniaturizing EBG structures to enable their placements in MIMO antenna systems.

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2. Novel Low Profile and Miniaturized Antennas

In this age of wireless communications, antennas perhaps represent the most important link in the entire communication system. Let us not forget that antennas are what make a communication system wireless in the first place. Antennas are simple structures that are intended to capture as much electromagnetic energy as possible. While communication devices are shrinking in size, antennas remain the most obstinate to follow suit. For instance, you can have an entire communication system on a chip, but the antenna will be several times larger than the chip, its package and its board. While there are fundamental limitations to the relationship governing the gain, bandwidth and the size of small antenna, the media that surrounds the antenna will have a strong impact on the antenna radiation characteristics.

Our research and interests on antennas is twofold: First, we are interested in miniaturizing antennas while maintaining acceptable levels of gain and efficiency, and second, we are interested in minimizing the profile of antennas by engineering

new “antenna media” using electromagnetic band gap concepts and metamaterials. In 2007, we were able to design artificial magnetic material with relatively high permeability operating in the microwave frequency region. This material can be used as a substrate to enhance the impedance bandwidth of low-profile antennas such as the ubiquitous microstrip antenna, or can be used as a superstrate (above the antenna) to enhance the gain.

3. Material with Negative Index of Refraction (NIR)

Negative index of refraction (NIR) media, also referred to as double negative media, has been envisioned in the 1960s but has been realized only recently in the late 90s. This new type of engineered material has wide ranging implications on radiating structures and devices. For instance, NIR makes possible a perfect lens, miniaturized microwave devices and higher gain antennas, to name only a few. The aspect that is of most interest to us is the ability of NIR to amplify evanescent waves (evanescent waves are the type of waves that do not propagate in space) and to control the directions of propagation for various applications.

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In our research, we are interested in developing mathematical and numerical models to predict the performance of various NIR media when interrogated with evanescent waves. Our interest is to assess the potential of NIR in enhancing near-field based non-invasive detection modalities. In recent work, our group was able to show conclusively that NIR media can increase the sensitivity of near-field probes, thus paving the way for a very exciting application of this not-so-exotic media after all!

4. Computational Electromagnetics

Computational electromagnetics (CEM) is the virtual electromagnetic laboratory where new design concepts from antennas to printed circuit boards are tested without fabrication. In this virtual laboratory, devices can be tested to find out if they emit too little or too much radiation for radiation regulatory compliance purposes. Antennas can be tested to find out if their performance is acceptable when they are positioned, say on top of a car or an aircraft.

While computational electromagnetics has matured in several respects, key challenges remain as more complex problems are considered which require higher resolution, wider dynamic range, and higher execution efficiency (for optimization). In our group, we are interested in numerical algorithms for the solution of Maxwell equations that are based on the Finite-Difference Time-Domain and Finite Element methods. Present research is focused on increasing the accuracy when using computational spaces having multi-resolution grid. Also, we are interested in the fundamental mechanism of instability in general time-domain methods. Recent work has also focused on developing highly robust and efficient finite element algorithm, based on the surface integral as a boundary condition, to understand the problem of field enhancement through plasmonic composites.

5. Photonics and Wave Chaos

Wave chaos is the study of the behavior of waves in chaotic cavities. What makes a cavity chaotic? Think of a billiard table, not the rectangular one, but a different shape. Position the Q ball at a certain location and shoot in a specific direction and follow the trajectory. Now, repeat the experiment but shoot the Q ball at a direction that is almost identical to the first one but slightly off, say by a tiny increment. If the trajectory of the second ball closely follows the trajectory of the first one, then this billiard table (or cavity) is non-chaotic. If the second trajectory follows a path which deviates significantly from the first one, then the billiard table, or cavity, is chaotic. Now, let us replace the Q ball with an electromagnetic ray or wave present in a metallic cavity, then we expect a behavior similar to the billiard table depending on whether the cavity is chaotic or not.

Depending on the topology of such cavities, the wave equation within chaotic cavities will result in a numerable infinite number of eigenvalues. The statistical distribution of these eigenvalues depends on the topology of the cavity. These distributions can be very costly to determine either experimentally or using numerical simulations. In our work, we are interested in developing semi-analytic expressions that allow fast determination of the eigenvalues spectrum for a wide class and important class of wave-chaos cavities. This work is in collaboration with the University of Oulu in Finland.

Journal Publications

F. Seydou, O. M. Ramahi and T. SeppÄanen, “Quasi-Analytical Computation of Energy Levels and Wave Functions in a Class of Chaotic Cavities with Inserted Objects,” in Mathematical Modeling, Simulation, Visualization and e-Learning, Dialla Konate, ed., pp. 3-15, Springer Berlin Heidelberg, 2007/8. (Book Chapter)

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B. Mohajer-Iravani and O. M. Ramahi, “Suppression of EMI and Electromagnetic Noise in Packages using Embedded Capacitance and Miniaturized Electromagnetic Bandgap Structures with high-k Dielectrics,” IEEE Transaction on Advanced Packaging, Vol. 30, No. 4, pp. 776-788, Nov. 2007. M. H. Kermani and O. M. Ramahi, “Application of the Complementary Derivatives Method in the ADI-FDTD Solution of Maxwell’s Equations,” IEEE Transaction on Antennas and Propagation, Vol. 55, No. 8, pp. 2294-2301, Aug. 2007. J. Qin, O. M. Ramahi and V. Granatstein, Novel planar electromagnetic bandgap structures for wideband noise suppression and EMI reduction in high speed circuits,” IEEE Transaction on Electromagnetic Compatibility, Vol. 49, No. 3, pp. 661-669, Aug. 2007. O. M. Ramahi, B. Mohajer-Iravani, J. Qin, S. Shahparnia and T. Kamgaing, “EMI Suppression and Switching Noise Mitigation in Packages and Boards using Electromagnetic Band Gap Structures,” in proceeding, International Symposium on Signals, Systems, and Electronics (ISSSE 2007), Montreal, Quebec, Canada, July 30- August 2, 2007, pp. 271-274. L. Yousefi, B. Mohajer-Iravani and O. M. Ramahi, “Enhanced Bandwidth Artificial Magnetic Ground Plane for Low-Profile Antennas,” IEEE Antennas and Propagation Letters, Vol. 6, pp. 289-292, June 2007. S. Shahparnia and O. M. Ramahi, “Design, Implementation and testing of Miniaturized Electromagnetic Bandgap Structures for Broadband Switching Noise Mitigation in High-speed PCBs,” IEEE Transactions on Advanced Packaging, Vol. 30, No. 2, pp. 171-179 May 2007.

Conference Papers/Presentation

B. Mohajer-Iravani and O. M. Ramahi, EMI Suppression in Microprocessor packages using Miniaturized Electromagnetic Bandgap Structures with high-k Dielectrics, IEEE EMC Symposium Digest, Honolulu, HI, July 8-11, 2007 F. Seydou, O. M. Ramahi, T SeppÄanen, “Annular Photonic Crystals: Computation and Analysis of the Green's Function,” in proceeding, IEEE Antennas and Propagation Society International Symposium, Honolulu, HI, June 10-15, 2007. M. S. Boybay and O. M. Ramahi, “Evanescent Field Detection Using Negative Refractive Index Lenses,” in proceeding, IEEE Antennas and Propagation Society International Symposium, Honolulu, HI, June 10-15, 2007. M. H. Kermani and O. M. Ramahi, “Application of the Complementary Derivatives Method in the ADI-FDTD Solution of Maxwell’s Equations,” in proceeding, IEEE Antennas and Propagation Society International Symposium, Honolulu, HI, June 10-15, 2007. L. Yousefi and O. M. Ramahi, “Miniaturized Wideband Antenna using Engineered Magnetic Materials with Multi-Resonator Inclusions,” in proceeding, IEEE Antennas and Propagation Society International Symposium, Honolulu, HI, June 10-15, 2007. B. Mohajer-Iravani and O. M. Ramahi, “Miniaturized Wideband Planar Electromagnetic Bandgap Structures Using high-k Dielectrics,” in proceeding, IEEE Antennas and Propagation Society International Symposium, Honolulu, HI, June 10-15, 2007. J. Qin, V. Granatstein, O. M. Ramahi, “Effect of Planar Electromagnetic Bandgap Structures on Signal Integrity,” in proceeding, IEEE Antennas and

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Propagation Society International Symposium, Honolulu, HI, June 10-15, 2007. A. Kabiri and O. M. Ramahi, “EwsTool: A Computer-Based Visualization Tool to Study 2-D Electromagnetic Scattering Phenomena,” in proceeding, IEEE Antennas and Propagation Society International Symposium, Honolulu, HI, June 10-15, 2007. L. Yousefi and O. M. Ramahi, “Engineered Magnetic Materials with Improved Dispersion using Multi-resonator Structures, in proceedings, 20th Canadian Conference on Electrical and Computer Engineering (CCECE 2007), Vancouver, BC, Canada, April 22-26, 2007, pp. 966-969. L. Yousefi, B. Mohajer-Iravani and O. M. Ramahi, “Low Profile Wide Band Antennas using Electromagnetic Bandgap Structures with Magneto-Dielectric Materials,” in proceeding, 2007 IEEE International Workshop on Antenna Technology: Small & Smart Antennas Metamaterials and Applications (IWAT 2007), Cambridge, UK, March 21-23, 2007. pp. 431-434. L. Yousefi and O. M. Ramahi, “New Artificial Magnetic Materials Based on Fractal Hilbert Curves,” in proceeding, 2007 IEEE International Workshop on Antenna Technology: Small & Smart Antennas Metamaterials and Applications (IWAT 2007), Cambridge, UK, March 21-23, 2007. pp. 237-240. F. Seydou, O. M. Ramahi, T. Seppanen, and K. Bizheva, Semi-analytical Model of Light Scattering form Living Cells, Biomedical Applications of Light Scattering (BO129), BIOS 2007. M. S. Boybay and O. M. Ramahi, “Double Negative Metamaterial for Subsurface Detection,” in proceeding, the 29th Annual International Conference of IEEE Engineering in Medicine and

Biology Society, Lyon, France, August 23-26, 2007. pp. 3485-3488. S. Abdallah, O. M. Ramahi, and K. Bizheva, “FDTD Simulation of Electromagnetic Wave Scattering from Retina Cells,” the 29th Annual International Conference of IEEE Engineering in Medicine and Biology Society, Lyon, France, August 23-26, 2007. pp. 1639-1642.

Students

PhD Students:

Ali Kabiri, Thesis Subject: Plasmonics.

Babak Alavikia, Thesis Subject: Computational Algorithms for Analyzing Field Enhancement Phenomena.

Hussein Attia, Thesis Subject: Miniaturized Antennas.

Leila Yousefi, Thesis Subject: Theory, Design and Development of Engineered Magnetic Materials.

Mani Kashanianfard, Thesis Subject: Microwave-based Detection Modalities.

Mohammed Mana Bait Suwailam, Thesis Subject: Reduction of Antenna Coupling in MIMO Systems.

Muhammed Said Boybay, Thesis Subject: Metamaterial Enhanced Evanescent Field Characterization for Subsurface Detection.

MSc Students:

Mohammad AlRamahi, Thesis Subject: Algorithms for Detection of Buried Object based on Microwave Modalities.

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Omar Ramahi can be reached via: Phone: 519-888-4567 Extension 37460

Email: oramahi@uwaterloo.ca

Safieddin Safavi-Naeini, Professor, received the B.Sc. in Electrical Engineering from University of Tehran, Tehran, Iran, 1974 and the M.Sc. and Ph.D. degrees in Electrical Engineering, both from University of Illinois (Champaign-Urbana), USA, in 1975 and 1979 respectively. He was Assistant and then Associate Professor at the University of Tehran, Electrical Engineering Department from 1980 to 1995 and has been with the Department of Electrical and Computer Engineering of the University of Waterloo, since 1996, where he is now a professor. Dr. Safavi's research interests and activities include numerical electromagnetics applied to analysis and design optimization of RF/microwave/millimeter

wave systems and circuits, antenna and propagation, wireless communication systems, very high speed digital circuits and photonics. He has been scientific and technical consultant to a number of national and international telecom industrial and research organizations over last 20 years.

Research Projects

1. Intelligent Multi-Antenna Radio Systems and Networks (iMARS)

(Collaborators: Prof. H. Jamali, Dr. Rafi, G. A. Shaker, J. Ahmadi-Shokouh, M. Mohajer-Jasebi, J. Khajehpour, S. Thiruchchelvam, E. Wang)

Next generation wireless communication and sensor networks require performance levels that are only realizable through flexible/reconfigurable radio-antenna technologies that will allow the radio module to quickly adapt and optimize its performance in response to fast time-varying physical and electronic environment. 

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This project is addressing novel multi-band multi-antenna radio-antenna architectures for emerging multi-antenna technologies (MIMO, Cognitive radio, smart antenna platforms…etc.) for communication and sensor networks.  

In this project miniaturized multi-element/multi-feed structures are explored for possible integration with passive/active control devices, engineered material (EBG, parasitic structures, …) for a wide range of applications.

In addition, a multi-antenna test-bed comprising flexible radio front-end and a software-defined physical layer, is under development. This will be used to experimentally verify novel radio system architectures and adaptive processes.

Electromagnetic interaction between the miniaturized integrated antenna and radio package with the human body is an important research sub-area in this project. 2. Low-Cost/Complexity Active Reconfigurable

Phased-Array Systems (Collaborators: Prof. H. Jamali, Dr. P. Mousavi, Dr. Rafi, Dr. D. Busuioc, M. Fakharzadeh, M. Hossu, K. Narimani, J. Qi, J. Cheng)

In this project planar and quasi-planar array technologies are being investigated for a number of applications such as land-mobile satellite communication, millimeter wave array for wireless LAN, car radar, and semi-mobile millimeter wave radio. A main focus in this research is to significantly extend the performance of low-cost multi-layer integration and packaging technologies to robust, accurate, and very fast beam-forming functions required in highly advanced radio systems, through complex and intelligent adaptive algorithm. One of the most promising results of this project so far is a fully functional active phased-array system for car-to-satellite communication. 3. Smart-Array-0n-Silicon (Collaborators: M.-Reza Nezhad-Ahmadi, H. Mirzaei, B. Biglarbegian, Raymond Zhu, M. Fahimnia)

A key to low-cost implementation of adaptive antenna-radio systems described in the project II is the integration of multi-channel gain blocks and phase/amplitude control devices required for the project I.2 on one chip. Advanced nano-scale CMOS and SiGe technologies are investigated to realize amplitude/phase control functions at frequencies beyond what is achievable today.

 

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Both conventional and unconventional (multi-port) ideas are being studied and investigated for push the boundaries of CMOS technologies for these applications. The direct integration antenna on chip (or on wafer) and in package are also investigated in this project.

4. Microwave and Terahertz Photonics Integrated System Research

(Collaborators: Prof. S. K. Chaudhuri, Dr. D. Saeedkia, Dr. A. Rohani, Dr. S. Gigoyan, M. Neshat, A. Arbabi, D. Hailu, B. Davudi, M. Khabiri, S. Taeb)

This research has now evolved into an extensive research program and a lab, Microwave and Terahertz Photonics Integrated System Lab (MISL), which is one of the four laboratories of a new national Center for Intelligent Antenna and Radio System (CAIRS) that will be established through an extensive CFI grant at the University of Waterloo. The MISL supports far reaching research in the area of millimeter-wave and terahertz (THz) photonics with emphasis on the THz applications in pharmaceutical and life sciences, communications, and radio astronomy. Researchers at the MISL, work on generation, manipulation, guidance, and detection of terahertz signals using photonic and optoelectronic techniques. One of the major research focuses is on the development of THz photonics devices and systems for biological and pharmaceutical spectroscopy and sensing and

medical imaging applications. They are particularly interested in the development of low-complexity and compact THz imagers/spectrometers, which will provide low-cost and easily accessible solutions for a vast number of advanced and vital health related applications, such as cancer diagnosis, gene therapy, and drug assessing/monitoring in pharmaceutical industry, which currently require costly and complex systems. These compact THz systems can be particularly used as disease diagnostic tools for the following: detecting skin and breast cancer – the second leading cause of death for woman from cancer in Canada; as label-free biological spectroscopy and sensing tools for early diagnosis of diseases or gene therapy; and as non-destructive real-time monitoring tools for the drug-manufacturing process and for testing the stability of tablets after production within the storage container or blister pack at drugstores. Theoretical and experimental investigation of novel material properties and surface plasmonic resonance devices in infra-red and THz is another important research direction in this group.

5. Photonics Devices and Signal Processing, Optical/THz MEMS

(Collaborators: Prof. S. K.Chaudhuri, Dr. M. Basha, M. Fakharzadeh, K. Bayat, S. Taeb)

Photonic technology and signal processing schemes can offer unique advantages and opportunities to adaptive radio-antenna system. Ultra-wide band array beam-forming is only possible through optical delay line methods applied to microwave/millimeter-

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wave modulated optical carrier. In this research, novel integrated radio-photonic system architectures and device technologies are investigated to achieve high performance beam-forming and other related optical signal processing. During the course of this research a versatile micro-assembly technology was developed and successfully applied to an optical MEMS micro-mirror for fast and accurate optical beam-switching. The developed structure can potentially evolve into a a very compact optical and

THz beam switch. The other project under investigation in this research is optical delay lines using Photonic Crystal (PC) concept. Several new structures have designed and optimized. Test structures have been fabricated and are currently under test. Similar methods can be applied to THz devices and systems. Application to novel bio-medical imagers and sensors are under consideration.

6. Computational Methods

(Collaborators: Prof. S. K.Chaudhuri, Dr. I. Ehtezazi, Dr. M. Basha, Dr. A. Rohani, P. Saleh-Anaraki, M. Fakharzadeh, D. Hailu)

Phenomena and structures under investigation in the aforementioned research activities often involve subtle electromagnetic and/or photonics interactions that have multi-resolution nature and therefore cannot be handled by existing commercial software simulation tools. Although the research group has access to extensive computational facilities and almost all mainstream software tools, application-specific fast and effective computational methods and models are still required to complement the

latter tools and provide a reliable design and simulation environment. The research activities are currently focused on: 1) fast analysis methods for infinite and finite periodic structures, 2) hybrid Gaussian Beam-Tracing-FDTD (GBT) method for optical and quasi-optical system simulation, 3) Spectral-Ray-Tracing (SRT) method for complex radiation and propagation phenomena in microwave/millimeter wave and THz system and devices.

7. “Center for Intelligent Antenna and Radio Systems” (CIARS)

(UW Collaborators: Prof. S. K.Chaudhuri, Prof. Jake Thiessen, Prof. A. K. Khandani)

Dr. S. Safavi-Naeini is currently leading a multi-university CFI infrastructure program which is aimed at the establishment a National “Center for Intelligent Antenna and Radio Systems” (CIARS). This is an extensive $12.5M research infrastructure project (2007-2012) that will create an integrated environment to support research on the aforementioned areas and other related multi-disciplinary areas, which, in terms of its scientific and technical capabilities, will be unique in Canada and among very few world-wide. Several universities, government agencies and leading telecom companies (U of Toronto, U of Manitoba, SFU, CRC, DRDC, RIM, and Nortel) have supported and are involved in this extensive research infrastructure project. In addition, CIARS will have several international collaborators. The CIARS will consist of four main laboratories:

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ERL (Electromagnetic Radiation Laboratory): Covering the antenna- and near-antenna radio-frequency circuits, ERL will consist of a state-of-the-art electromagnetic radiation test chamber with test capability from 0.5 GHz to 600 GHz – a vast frequency range which will make ERL a unique facility in Canada and one of very few such facilities in the world. This laboratory will be expanded into the terahertz range.

MISL (Microwave and Terahertz Photonics Integrated System Lab): MISL will include instrumentation for ultra-broad band signal, integrated and hybrid circuits, and system characterization. MISL will enable a broad range of performance characterization over a spectrum of frequencies that extends into sub-millimeter waves (500 GHz and beyond), a frequency range unique in Canada. This lab will also include a THz signal generation, detection, and spectrum analysis setup, whose development is in its final stage.

MCRL (Multi-Channel Radio Communication System Characterization Laboratory): Covering the physical layer, MCRL houses a highly flexible multi-channel radio communication system simulator. Integration with the other CIARS labs will allow system software and radio-antenna hardware research to be carried on simultaneously, leading to a truly integrated multi-faceted environment for exploring novel globally optimized radio system architectures.

RPF (Rapid Prototyping Facility): Supporting the above three laboratories by providing a state-of-the-art multi-layer onsite fabrication facility. This will cut experimental lead-time from months to hours.

Journal Publications

Z. Yan, A. H. Majedi, and S. Safavi-Naeini, “Physical Modeling of Hot-Electron Superconducting Single Photon Detectors,” IEEE

Transactions on Applied Superconductivity, vol. 17, no. 3, pp. 3789-3794, Sept. 2007. M. Basha, S. K. Chaudhuri H. J. Eom, and S. Safavi-Naeini, “A generalized formulation for electromagnetic plane wave scattering from a general shaped groove in a perfectly conducting plane”, Journal of the Optical Society of America A, vol. 24, no. 6, June 2007. K. Bayat, S. K. Chaudhuri, S. Safavi-Naeini, “Polarization and thickness dependent guiding in the photonic crystal slab waveguide,” Optics Express, vol. 15, Issue 13, pp. 8391-8400, June 2007. A. Khajehnasiri, S. Safavi-Naeini, "A Generalized 2-D Multiport Model for Planar Circuits with Slots in Ground Plane", IEEE Trans. Antennas Propagat., vol. 55, no. 5, pp. 1283-1292, May 2007. M. Basha, N. Dechev, S. Safavi-Naeini, S. K. Chaudhuri, “A scalable 1 X N optical MEMS switch architecture utilizing a microassembled rotating micromirror”, IEEE Journal of Selected Topics in Quantum Electronics, vol. 13, issue 2, pp. 336-347, April 2007. G. A. Shaker, S. Safavi-Naeini, “Design Approach for Realizing Two-Dimensional Electromagnetic Band Gap Structures”, Microwave and Optical Technology Letter, vol. 49, Issue 5, pp. 1189-1192, March 2007. D. Saeedkia, S. Safavi-Naeini, “Modeling and Analysis of a Multilayer Dielectric Slab Waveguide with Applications in Edge-Coupled Terahertz Photomixer Sources”, IEEE/OSA J. of Lightwave Technol., vol. 25, No. 1, pp. 432-439, Jan. 2007.

Conference Papers/Presentation

A. Malarky, Gh. Rafi, S. Safavi-Naeini, “A Planar Dual Band GPS and DSRC Antenna for Road

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Vehicles,” IEEE 66th Vehicular Technology Conference 2007, pp. 2096-2100, Oct. 2007. M. Neshat, D. Saeedkia, M. Nagel, S. Safavi-Naeini, “Electromagnetic Modeling of the DNA monolayer in THz Bio-chips,” 2007 IRMMW-THz, Cambridge, UK, Sept. 2007. M. Neshat, S. Gigoyan, D. Saedkia, M. Nagel, S. Safavi-Naeini, “Mode-Selective Dielectric Resonator Coupled to Dielectric image waveguide for mm-Wave sensing applicationss,” 2007 IRMMW-TH, Cambridge, UK, Sept. 2007 M. Basha, S. K. Chaudhuri, S. Safavi-Naeini, “Electromagnetic Scattering From Multiple Arbitrary Shape Grooves: A Generalized Formulation,”, 2007 IEEE/MTT-S International Microwave Symposium, pp. 1935-1938, June 2007.M. M. Nezhad-Ahmadi, S. Safavi-Naeini, “On-chip Antennas for 24, 60, and 77GHz Single Package Transceivers on Low Resistivity Silicon Substrate,” 2007 IEEE Antennas and Propagation Society Symposium, Hawaii (USA), pp. 5059 – 5062, June 2007. M. Fakharzadeh, S. Safavi-Naeini, S.H. Jamali, P. Mousavi, K. Narimani, “Accurate limited Angle Tracking with a Phase Array Antenna Using Zero-Knowledge Beamforming, “ 2007 IEEE Antennas and Propagation Society Symposium, Hawaii (USA), pp. 1104-1107, June 2007. M. Fakharzadeh, S. Safavi-Naeini, S.H. Jamali, P. Mousavi, K. Narimani, “Fast Stochastic Beamforming for Mobile Phased Array Antennas,” 2007 IEEE Antennas and Propagation Society Symposium, Hawaii (USA), pp. 1945-1948, June 2007. D. Busuioc, M. Shahabadi, A. Borji, G. A. Shaker, and S. Safavi-Naeini, “Substrate Integrated

Waveguide Antenna Feed - Design Methodology and Validation,” 2007 IEEE Antennas and Propagation Society Symposium, Hawaii (USA), pp. 2666-2669, June 2007. G. A. Shaker, D. Busuioc, S. Safavi-Naeini, “Small Antenna over an Engineered Ground Plane,” 2007 IEEE Antennas and Propagation Society Symposium, Hawaii (USA), pp. 4072-4075, June 2007. G. A. Shaker, S. Safavi-Naeini, D. Busuioc, “Design Routine for Realizing Miniaturized Planar Antennas,”2007 IEEE Antennas and Propagation Society Symposium, Hawaii (USA), pp. 5989-5992, June 2007. D. Busuioc, G. A. Shaker, S. Safavi-Naeini, “Coupled Resonator Filter Synthesis and Design Optimization for PCS Wireless Communications,” 2007 IEEE Antennas and Propagation Society Symposium, Hawaii (USA), pp. 3137-3140, June 2007. D. Busuioc, G. A.Shaker, M. Shahabadi, S. Safavi-Naeini, “Substrate integrated waveguide radial power divider for Ka-Band satellite applications,” 2007 IEEE Antennas and Propagation Society Symposium, Hawaii (USA), pp. 4244-4247, June 2007. D. Saeedkia, M. Neshat, S. Safavi-Naeini, and R. Sabry, “An integrated continuous-wave terahertz biosensor,” SPIE Conference on Terahertz for Millitary and Security Applications, Orlando, April 2007 (Invited Paper). M. Neshat, D. Saeedkia, S. Safavi-Naeini, “A THz Transducer for On-Chip Label-Free DNA Sensing,” 2007 Optical Terahertz Science and Technology, Orlando, March 2007. M.Neshat, D. Saeddkia, S. Safavi-Naeini, “On the Behavior of the Radiation Field from Large-

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Aperture Terahertz Photoconductive Antenna under Impulsive Excitation,” 2007 IEEE International Workshop on Antenna Technology 2007 (iWAT07), "Small and Smart Antennas, Metamaterials and Applications", Cambridge, UK, March 2007. M.Neshat, D. Saeddkia, S. Safavi-Naeini, ” Low Profile Double Negative Lens Antenna,” 2007 IEEE International Workshop on Antenna Technology 2007 (iWAT07), "Small and Smart Antennas, Metamaterials and Applications" , Cambridge, UK, March 2007. G. A. Shaker, S. Safavi-Naein,” A Technique for Realizing Compact Arrays of Microstrip Antennas “,2007 IEEE Radio and Wireless Symposium, pp. 249-252, Jan. 2007. G. A. Shaker, S. Safavi-Naein,” Highly miniaturized fractal antennas“, 2007 IEEE Radio and Wireless Symposium, pp. 125-128, Jan. 2007. G. A. Shaker, S. Safavi-Naein,” Design Approach for Integration of Antennas with Electromagnetic Band Gap Structures “, 2007 IEEE Radio and Wireless Symposium, Jan. 2007. M. R. Nezhad Ahmadi, S. Safavi-Naeini, L. Zhu, “An Efficient CMOS On-Chip Antenna Structure for System in Package Transceiver Applications ", 2007 IEEE Radio and Wireless Symposium, pp. 487-490 Jan. 2007. J. Ahmadi-Shokouh, S. H. Jamali, S. Safavi-Naeini,"On the Optimality of SPRAS-MIMO for Spatial Multiplexing Transmission", 2007 IEEE Radio and Wireless Symposium, pp. 531-534, Jan. 2007.

Other Highlights

S. Safavi-Naeini, “Conformal Integrated Antenna/Radio and System Simulator for Intelligent Multi-Standard Radio Networks,” Final Report for

OCE, OCE/CITO Research Partnership Program (Round 8.1), Dec. 2007. D. Saeedkia and S. Safavi-Naeini, “Investigation and Development of a Dual-Mode Terahertz Spectrometer and Imager Using Photoconductive Sources and Detectors,” Year 1 Progress Report for OCE, OCE/CITO Research Partnership Program, Dec. 2007. S. Safavi-Naeini, “NSERC-Research in Motion Industrial Research Chair in Intelligent Integrated Radio/Antenna Systems and Novel Electromagnetic Media Technologies”, [Project No. 320316-03], Progress Report and Presentation, Nov. 2007.

Awards

Grants Dr. S. Safavi-Naeini, has been awarded $406,450 funding from OCE (CITO) for his project on “Investigation and Development of Dual-Mode Terahertz Spectrometer and Imager Using Photoconductive Source and Detector”.

Students

PhD Students

A. Arbabi, Thesis Subject: Sub-Millimeter wave signal generation

B. Biglarbegian, Thesis Subject: Active phased-array systems

Bahar Davoudi , Thesis Subject: THz imaging

D. Hailu, Thesis Subject: THz integrated structures

Edward Wong, Thesis Subject: Identification/Location-finding radio network technologies.

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H. Mirzaei, Thesis Subject: Millimeter-wave integrated circuit front-end for phased-array systems.

M. Basha, Thesis Subject : Design and analysis of novel MEMS structures for photonic switches and tunable components.

M. Elnaggar, Thesis Subject: EM-adaptive MIMO systems.

M. Mohajer-Jasebi, Thesis Subject: Optimized multi-antenna package for capacity enhancement.

Mehrdad Fahimnia, Thesis Subject: Multi-channel mmW MMIC.

P. Saleh-Anaraki, Thesis Subject: Fast computational method for periodic structures.

S. Thiruchchelvam, Thesis Subject: Multi-antenna communication/tracking systems

Sareh Taebi, Thesis Subject: Photonic-THz Signal Processing.

MSc. Students

M. Hossu, Thesis Subject: Integrated analog signal processors for smart antenna systems.

S. Li, Thesis Subject: Radio-on-Fiber for heterogeneous radio networks.

Safieddin Safavi-Naeini can be reached via: Phone: 519-888-4567 Extension 32822 Email: safavi@maxwell.uwaterloo.ca

Simarjeet Singh Saini, Assistant Professor, joined the group in Sept. 2007. His expertise is in the field of photonics especially monolithic integration of active and passive devices. He did his Ph.D. from the University of Maryland, College Park in 2001. The research conducted as part of his thesis lead to the development of a new

platform technology for monolithic integration called the Passive Active Resonant Coupler Platform (PARC) and formation of a startup company Quantum Photonics (currently Covega) to commercialize products based on the research. Dr. Saini joined the company in Dec. 2000 at a senior research position and lead the development of multiple product lines including Covega’s world leading optical gain chips for tunable lasers, semiconductor optical amplifiers, high power lasers and integrated circuits. In 2004, he also co-founded another start-up called Altanet Networks to build fault tolerant Ethernet based networks for metro applications using intelligence in the optical domain.

Today Prof. Saini is considered to be an acknowledged leader in the field of integrated photonics, high power lasers and semiconductor optical amplifiers. He was invited to present his work on high power lasers in Photonics West in Jan. 2007. In that paper, a modeling scheme for predicting the performance of lasers under high thermal stress was described and the devices optimized by using the model were demonstrated.

Research Projects

1. Integrated Devices for Fiber to the Home Network (FTTH)

In order to bring larger bandwidth to the home, it is envisioned that fiber will be installed up to the home. This has already started to happen in a time division multiplexed schemes using Passive Optical Networks (PON). The next generation of the networks will use Wavelength Division Multiplexing (WDM) to further increase the bandwidth. However, the devices required will need to be low cost. Prof. Saini is using his experience in monolithic integration and high power lasers to make devices that do not need cooling and integrate them together onto a single chip. A patent was filed for last year for a new kind of a device that can be

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used for WDM-PON. He has currently a Ph.D. student, Sareh Taebi, who is working on designing various devices that can be used for WDM-PON applications. 2. Optical Packet Recognition and Packet

Switching

On the other end of the spectrum, future high speed networks will need to be agile. It is envisioned that there will be paradigm shift and the networks will use an optical packet switched regime where each packet is processed at the node and routed accordingly. Prof. Saini is working on a network architecture where the address of the optical packets are deciphered all-optically without converting the packet into the electrical domain and the packet routed to the correct destination. He is building integrated optical switches for both logic and space switching in order to achieve the all-optical network. This project is in collaboration with University of Maryland. 3. Gain Chips for Tunable Laser in Far-

Infrared

Having developed gain chips for tunable lasers in the telecom wavelengths which have captured more than 90 % of the worldwide market due to their superior performance, Prof. Saini has now turned his attention to developed similar chips for the wavelength region from 3-10 microns. This region is highly interesting as most of the gases have direct band absorption in this wavelength region. This project is in collaboration with University of Maryland. 4. Chemical-Biological Sensors with Integrated

Optics Prof. Saini demonstrated Chemical-Biological using Fiber Bragg gratings over the last couple of years. He has now started to work on similar sensors using

integrated optics to achieve higher functionality and multiplexing of the sensors. Students PhD Students: Sareh Taebi, Thesis Subject: Integrated Photonics circuits for WDM-PON Fiber to the Home Networks.

Simarjeet Singh Saini can be reached via: Phone: 519-888-4567 Extension 35780 Email: sssaini@ecemail.uwaterloo.ca