DUAL-BAND H-SHAPED SLOT ANTENNAFOR 2.4 AND 5 GHz WIRELESSCOMMUNICATION

Yun Liu, Zhenyi Niu, and Xiaojun WangCollege of Information Science and Technology, Nanjing Universityof Aeronautics and Astronautics, Nanjing 210016, People’sRepublic of China; Corresponding author: liuyun19851010@yahoo.com.cn

Received 14 June 2009

ABSTRACT: A simple and compact dual-band H-shaped slot antennafor wireless local area network applications is proposed. The proposed

antenna is composed of an H-shaped slot on the ground plane with sizeof 23 mm by 32 mm. The substrate material is foam. The antenna is fed

by microstrip at its top. The impedance bandwidth, radiation pattern,and gain of the antenna were simulated. The results show that theantenna just covers the WLAN bands (2.4–2.485, 5.15–5.35, and

5.725–5.825 GHz), with the gain remaining steady. The measurementof impedance bandwidth was carried out with a network analyzer.

A good agreement between measurement and simulation can beobserved. VC 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett

52: 957–959, 2010; Published online in Wiley InterScience

(www.interscience.wiley.com). DOI 10.1002/mop.25042

Key words: H-shaped slot antenna; dual-band; wireless local areanetwork (WLAN); microstrip

1. INTRODUCTION

With the rapid developments in wireless communication technol-

ogy, dual-band antenna design becomes very important for wire-

less local area network (WLAN) operating at the 2.4 GHz (2.4–

2.485 GHz) and 5 GHz (5.15–5.825 GHz) bands. The slot

antenna fed by microstrip line is one type of microstrip antenna

which has special advantages such its simple structure, wider

bandwidth, less conductor loss, and better isolation between the

radiating element and feeding network [1–3]. It can also provide

the merits of low profile, low cost, small size, and easier integra-

tion with other circuits and conformability to a shaped surface.

For IEEE 802.11a/b/g and HIPERLAN applications, numer-

ous slot antennas operating at 2.4/5 GHz have been reported

during these years [4–6]. These slot antennas only covers part of

the 2.4/5 GHz bands, and these antennas are not very compact.

In literature, some antennas can wholly cover the 2.4/5 GHz

bands but are not very compact. Based on the previous

researches, this article proposed an H-shaped slot antenna fed by

microstrip line for desirable frequency and bandwidth. The sim-

ulations are carried out using finite element method software

‘‘High Frequency Structure Simulator,’’ HFSS Ver. 10.

In this article, a compact slot antenna area of 23 mm by 32 mm

is first proposed. Then the impedance bandwidth, radiation pat-

tern, and gain of the antenna were simulated, and the results show

that the antenna just covers the WLAN bands (2.4–2.485, 5.15–

5.35, and 5.725–5.825 GHz), with the gain remaining steady.

The obtained bandwidths for 2.4 and 5 GHz bands are 120

and 1000 MHz, respectively. Details of the antenna design and

simulation are presented in this article.

2. ANTENNA DESIGN

The geometry and configuration of the slot antenna is shown in

Figure 1. The antenna was fabricated on an h ¼ 4 mm substrate

with dielectric constant e ¼ 1.0. The proposed antenna is com-

posed of an H-shaped slot on the ground plane with size of 23 mm

by 32 mm. The substrate material is air. The antenna is fed by

microstrip at its top, which is terminated with a subminiature

A connector for measurement purpose. The total external size of

H-shaped slot is W � L, and the depression part’s size is d � m.The corresponding antenna parameters are given in Table 1.

3. NUMERICAL RESULTS

The performance of the proposed antenna such as impedance

bandwidth, radiation pattern, and gain are simulated by HFSS

10. To verify the accuracy of simulation results, the antenna

Figure 1 Geometry of the proposed slot antenna

TABLE 1 Geometry Parameters of Antenna 1

Parameters Wg Lg s h d L W g

Value (mm) 21 32 7.5 4 11 24 17 11

Figure 2 The fabricated antenna. [Color figure can be viewed in the

online issue, which is available at www.interscience.wiley.com]

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 52, No. 4, April 2010 957

was fabricated (shown in Fig. 2), and its impedance bandwidth

was tested by the vector network analyzer.

The measured and simulated impedance bandwidth is shown

in Figure 3. In the low frequency, the measured and simulated

results have a good agreement; the bandwidth for 2.4 GHz

is 120 MHz (2.4–2.52 GHz), the minimum return loss is

�11.5 dB. The resonant frequency shift occurs in 5 GHz band,

and the bandwidth is 1600 MHz (4.7–6.3 GHz) and its minimum

return loss is �25 dB.

The Figure 4 gives the simulated radiation patterns at 2.45

and 5.49 GHz. The patterns in the H-plane are quite omnidirec-

tional, as expected. In the E-plane, the radiation patterns remain

roughly a dumbbell shape, and they are bidirectional.

Figure 5 presents the peak gain of the proposed dual-band

slot antenna. In 2.4 GHz band, the peak gain is about 2.3 dBi,

with less than 0.65 dBi of gain variation. In 5.15–5.35 GHz

band, the peak gain is about 4.84 dBi, and the gain variation is

less than 0.4 dBi; in 5.725–5.825 GHz band, the peak gain is

about 4.97 dBi, and the gain variation is less than 0.2 dBi.

4. CONCLUSIONS

This article proposed a simple and compact slot antenna for wire-

less communication. The antenna completely covers the WLAN

bands (2.4–2.485, 5.15–5.35, and 5.725–5.825 GHz), that is

Figure 3 Measured and simulated impedance bandwidth of antenna.

[Color figure can be viewed in the online issue, which is available at

www.interscience.wiley.com]

Figure 5 Peak gains at 2.4 and 5 GHz bands

Figure 4 Radiation patterns at 2.45 and 5.49 GHz. (a) 2.45 GHz and

(b) 5.49 GHz. [Color figure can be viewed in the online issue, which is

available at www.interscience.wiley.com]

958 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 52, No. 4, April 2010 DOI 10.1002/mop

enough for IEEE 802.11a/b/g specifications. The proposed

dual-band slot antenna provides the frequency ratio of two

operating modes tuned in the range of 1.98–2.5. The gain of the

proposed antenna can fully meet the requirements of wireless

applications.

REFERENCES

1. S.N. Ysai, H.H. Hsin, H.K. Dai, and K.T. Cheng, Arcuate slot

antenna assembly, US Patent 6,373,443, 2002.

2. A. Axelrod, M. Kisliuk, and J. Maoz, Broadband microstrip-fed

slot radiator, Microwave J 32 (1989), 811–84.

3. H.G. Akhavan and D.M. Syahkal, Study of coupled slot antennas

fed by microstrip lines, In: The 10th International Conference on

Antennas and Propagation, 1999, pp. 1290–1292.

4. C.W. Liu, Broadband dual-frequency cross-shaped slot cpw-fed

monopole antenna for WLAN operation, Microwave Opt Technol

Lett 46 (2005), 353–355.

5. H.M. Hsiao, J.W. Wu, and Y.D. Wang, Novel dual-broadband rec-

tangular-slot antenna for 2.4/5-GHz wireless communication,

Microwave Opt Technol Lett 46 (2005), 197–201.

6. J.W. Wu, 2.4/5-GHz dual-band triangular slot antenna with com-

pact operation, Microwave Opt Technol Lett 45 (2005), 81–84.

VC 2010 Wiley Periodicals, Inc.

PHOTON TRAPPING MODEL WITHIN AFIBER BRAGG GRATING FOR DYNAMICOPTICAL TWEEZERS USE

P. P. Yupapin,1 T. Saktioto,2 and J. Ali31 Advanced Research Center for Photonics, Faculty of Science,King Mongkut’s Institute of Technology Ladkrabang, Bangkok10520, Thailand; Corresponding author: kypreech@kmitl.ac.th2 Physics Department, Math and Sciences Faculty, University ofRiau, Panam Pekanbaru, Indonesia3 Institute of Advanced Photonics Sciences, Science Faculty,Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru,Malaysia

Received 18 June 2009

ABSTRACT: We propose a new potential model that can be used todescribe the trapped photon within a fiber Bragg grating, which istrapped by the potential well. We found that the localized, i.e., trapped

soliton within the fiber Bragg grating is seen. The soliton well within adark soliton has been observed using the forward and backward

pumping of the S-band erbium doped fiber. The process of stimulatedBrillouin scattering is described as a nonlinear interaction between thepump and the Stokes fields through an acoustic wave. As both energy

and momentum are conserved during each scattering process, theannihilation of pump photon creates Stokes photon and an acoustic

phonon simultaneously. The destruction interference is seen as the darksoliton valley, i.e., well, which is surrounded by the intense optical field,which is formed by the potential well. The application of such a

behavior is that the dynamic probing tool known as an optical tweezerscan be used. Moreover, the novel aspect for dynamic optical tweezers is

plausible, where the trapped pulse or molecule can be moved, i.e.,transportation. VC 2010 Wiley Periodicals, Inc. Microwave Opt Technol

Lett 52: 959–961, 2010; Published online in Wiley InterScience

(www.interscience.wiley.com). DOI 10.1002/mop.25043

Key words: potential model; photon trapping; soliton trapping;dark soliton; dark soliton valley

1. INTRODUCTION

A dark soliton exhibits an interesting and remarkable behavior,

when it is transmitted into an optical transmission system. It has

the advantage of signal security, when the ambiguity of signal

detection becomes a problem of the decipher. Recently, Sarapat

et al. [1] have shown that the conversion of a dark soliton into a

bright soliton can be realized by using an add/drop filter. Here,

the secured signals in the transmission are retrieved using a suit-

able add/drop filter that is connected to the transmission line.

The other promising application of a dark soliton signal [2] is

for the large guard band of two different frequencies, which can

be achieved by using a dark soliton generation scheme. Further-

more, the dark soliton pulse shows a more stable behavior than

the bright solitons with respect to the perturbations such as am-

plifier noise, fiber losses, and intra-pulse stimulated Raman scat-

tering [3]. It is found that the dark soliton pulses propagation in

a lossy fiber, spreads in time at approximately half the rate of

bright solitons. One pays, however, for these advantages when

generating dark soliton pulses. The other behavior is that dark

soliton pulses are difficult to detect than the bright soliton pulses

[4]. Many earlier works of dark soliton in fiber optics are found

in Refs. [5–7]. Firstly, in this article, we consider the Stokes pa-

rameters for important information on the total energy and

energy difference between the forward and backward propagat-

ing modes. The motion of a particle moving as a photon is

shown with the classic anharmonic potential. The beta parameter

is set to zero because of power conservation along the grating

structures. The results obtained have shown that the optimum

points of potential well decrease exponentially when the alpha

values are increased and vice versa for gamma. Further descrip-

tion of the effect of alpha and gamma to obtain the optimized

point of the potential well is also given. Secondly, we report the

generation of the dark soliton using the forward and backward

pumping of the S-band erbium doped fiber. The process of

stimulated Brillouin scattering is described as a nonlinear inter-

action between the pump and the Stokes fields through an

acoustic wave. The pump signal will generate an acoustic wave

that later modulates the refractive index of the medium; hence

producing an index grating that scatters light to a lower fre-

quency in the forward and backward direction. As both energy

and momentum are conserved during each scattering process,

the annihilation of pump photon creates a Stokes photon and an

acoustic phonon simultaneously.

2. PHOTON TRAPPING IN A POTENTIAL WELL

Wave propagation in optical fibers is analyzed by solving Max-

well’s Equation with appropriate boundary conditions. In the

presence of Kerr nonlinearity, using the coupled-mode theory,

the nonlinear coupled mode (NLCM) equation is defined under

the absence of material and waveguide dispersive effects. The

dispersion arising from the periodic structure dominates near

Bragg resonance conditions, and it is valid only for wavelengths

close to the Bragg wavelength. By substituting the stationary so-

lution to the coupled mode equation and by assuming

E6ðz; tÞ ¼ e6ðzÞe�i~dct=�n, we obtain

idefdz

þ d̂ef þ jeb þ Cs efj j2 þ Cx ebj j2� �

ef ¼ 0;

idebdz

þ d̂eb þ jef þ Cs ebj j2 þ 2Cx efj j2� �

eb ¼ 0:

(1)

Equation (1) represents the time-independent light transmis-

sion through the gratings structure where ef and eb are the for-

ward and backward propagating modes [8]. To explain the for-

mation of Bragg soliton, consider the Stokes parameter, because

it provides useful information about the total energy and energy

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 52, No. 4, April 2010 959