On the Determination of the Impulse Response of Ultra-Wideband Antennas
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Transcript of On the Determination of the Impulse Response of Ultra-Wideband Antennas
On the determination of the impulse response ofOn the determination of the impulse response ofUltra-wideband antennas
S. Sczyslo, G. Armbrecht, H. Thye, S. Dortmund and T. Kaisery , , y ,
Motivation
Each path of the impulse response between two antennas can be separated:
Knowledge of the directional antenna impulse response (IR) allows for:
Derivation of different antenna parameters, e.g. gain, goup delay
more realistic simulations e.g. in a raytracing environmentmore realistic simulations e.g. in a raytracing environment
design of more efficient receivers
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 2
Motivation
Antenna receive IR relates the incident E-field with the signal at the antenna feeding port by:
Antenna transmt IR relates the signal at the feeding port with the transmitted E-Antenna transmt IR relates the signal at the feeding port with the transmitted E-field by:
Antenna transmit and receive IR relation given by Lorentz reciprocity:
=> Transmit Simulation in CST Microwave Studio can be used to characterize a passive antenna
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 3
Motivation
A new method, the GTEM method, is presented using an easy setup to determine the receive IR:
Its final equation is very close to the definition equation of the receive IR:
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 4
Outline
Introduction of the cone antenna
Simulation of the antenna IR using CST MWS
Simulation Setupp Deconvolution Presentation of the CST / MATLAB framework Results and ComparisonResults and Comparison
Measurement of the antenna IR using the GTEM Method
Pulse propagation in GTEM Cells Method description Results and Comparison
Conclusion
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 5
Outline
Introduction of the cone antenna
Simulation of the antenna IR using CST MWS
Simulation Setupp Presentation of the CST / MATLAB framework Results
Measurement of the antenna IR using the GTEM Method
Pulse propagation in GTEM Cells Method description Results and Comparison
Conclusion
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 6
Introduction of the cone antenna
UWB cone antenna
mechanically simple to guarantee identical antennas
nearly omnidirectional pattern=> single impulse response to characterize azimuth plane
low cross polarization
compact size (20 mm x 20 mm x 20 mm)
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 7
Outline
Introduction of the cone antenna
Simulation of the antenna IR using CST MWS
Simulation Setupp Presentation of the CST / MATLAB framework Results and Comparison
Measurement of the antenna IR using the GTEM Method
Pulse propagation in GTEM Cells Method description Results and Comparison
Conclusion
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 8
Simulation Setup
Determine antenna transmit IR:• Extract E-field component in farfield condition• Extract excitation signal• Extract excitation signal• Deconvolve both signals
E-field probes (farfield) Broadband Farfield Monitor
• Time consuming to define all probes • Check Farfield/RCS• Check Transient farfields
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 9
Deconvolution
Applying a Wiener filter in the FD leads to the following deconvolution(see also [1]) :
λ aims to bound in case of low SNR. Identify signal+noise and noise parts of the energy spectral density
λ can be calculated with the “noise“ part which is limited by ωs:
[1] S. Sczyslo, H. Thye, G. Armbrecht, S. Dortmund, and T. Kaiser, “Determination of the impulse response of uwb antennas using gtem cells,” in Ultra-Wideband, 2009. ICUWB 2009. IEEE International Conference on, Sept 2009 pp 753 758
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 10
Sept. 2009, pp. 753–758.
CST -> MATLAB Framework Export Farfield
Framework allows for conversion of Antenna Farfield to MATLAB (time & freq dependent)
Extraction of different parameters in MATLAB e.g. antenna impulse response, Gain Macro in CST includes GUI MATLAB script is guided in command line (GUI in next version) Downloadable soon (May 2010 after evaluation) at:Downloadable soon (May 2010 after evaluation) at:
http://www.ikt.uni-hannover.de/software.html
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 11
Results
Plane wave to indicate to Lorentz reciprocity
Perfect matching between all three extraction methods
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 12
Outline
Introduction of the cone antenna
Simulation of the antenna IR using CST MWS
Simulation Setupp Presentation of the CST / MATLAB framework Results and Comparison
Measurement of the antenna IR using the GTEM Method
Pulse propagation in GTEM Cells Method description Results and Comparison
Conclusion
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 13
Pulse propagation in GTEM cell
absorber
septum resistor network
input port
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 14
Simulation of pulse propagation in GTEM cell
1.2
Excitation pulse
0.8
1.0
tude
Excitation pulse Simulated Ey in CS1
CS2CS1
0.4
0.6
aliz
ed a
mpl
it
P1 P2
0.0
0.2
nor
ma
• TEM id d l d 20
0 2 4 6 8-0.2
time [ns]
• TEM waveguide developed 20 years ago• frequently used measurement device in EMC for immunity and emission
measurements
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 15
Measurement of pulse propagation in GTEM cell
downtime t defines the time intervall until reflections occur at the measurement position downtime tD defines the time intervall until reflections occur at the measurement position
reflections are related to the rear end of the cell
IR of GTEM cell can be modelled by a weighted dirac impulse response (see also [2]) IR of GTEM cell can be modelled by a weighted dirac impulse response (see also [2])
[2] H. Thye, G. Armbrecht, and M. Koch, “Pulse propagation in gigahertz transverse electromagnetic cells,” in IEEE Transactions on Electromagnetic Compatibility, vol. 51, no. 3, Aug. 2009.
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 16
g p y, , , g
GTEM method: System Theory Model of the Setup
As has been shown the impulse response of the GTEM cell can be modeled by a weigthed Dirac impulse within downtime tD
=> applying time gating techniques, the IR can be modeled by:
=>
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 17
GTEM method: Tradeoff in antenna placement
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 18
GTEM method: Measurement Setup
GTEM 5305 Cone antenna inside the GTEM cellPulse Generator
PicoSecond 4015D
S li O illSampling Oscillocope Agilent Infinium 86100B
Pulse Generator: A = -1.9 V t 22tFWHM = 22ps
Oscilloscope: av_cycle = 1024t scale = 500 ps/divt_scale = 500 ps/div Npoints = 405 pts/div (interpolation)
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 19
Results using a cutoff frequency fc = 15GHz
nearly perfect match between CST simulation and measurement withGTEM methodGTEM method
slight oscillations for t > 0.3 ns
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 20
Outline
Introduction of the cone antenna
Simulation of the antenna IR using CST MWS
Simulation Setupp Presentation of the CST / MATLAB framework Results and Comparison
Measurement of the antenna IR using the GTEM Method
Pulse propagation in GTEM Cells Method description Results and Comparison
Conclusion
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 21
Conclusion
• It was shown how to determine the impulse response of an antenna by simulation and measurementsimulation and measurement
• A new framework taking advantage of CST MWS’s farfield monitor and MATLAB t dwas presented
• GTEM method was presented as an efficient method to measure the antenna impulse response
• a nearly perfect match between both methods could have been achieveda nearly perfect match between both methods could have been achieved
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 22
Thank you for your attentionThank you for your attention
On the determination of the impulse response of Ultra-wideband antennasCST User Group Meeting 2010 S.Sczyslo 2323