Antenna for WLAN/WiMAX/RFID Applications

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Wideband Compact Double Inverted-F

Antenna for WLAN/WiMAX/RFID Applications

Debabrata Kumar Karmokar, Khaled Mahbub Morshed, Md. Selim Hossain, Md. Aminur Rahman, Md. Nurunnabi Mollah

Abstract—This paper presents a wideband compact double Inverted-F antenna (DIFA) for WLAN/WiMAX/RFID applications by means of numerical simulation. The antenna has compact size of 9×18 mm² and provides a wide bandwidth of 2.5 GHz (5000MHz~7500MHz) which cover the 5.2 GHz WLAN, 5.5 GHz WiMAX and 5.8 GHz WLAN/RFID application bands. Moreover it has very high peak gain of 7.14, 7.11 and 6.50 dBi with less than 0.5, 0.7 and 0.6 dBi gain variation within the 10 dB return loss bandwidth at 5.2, 5.5 and 5.8 GHz band respectively. Also the VSWR of DIFA varies from 1.09877 to 1.61467 within the antenna bandwidth.

Keywords— Inverted-F antenna (IFA), Double IFA (DIFA), Radio frequency identification (RFID), Worldwide interoperability for microwave access (WiMAX), Wireless local area networks (WLAN).

1 I

NTRODUCTION

ODERN wireless communication systems are ris- ing rapidly and the function of these devices is increasing as well as the size decreasing. The size of the antenna often has a great influence on the whole size of wireless systems so for meet up the demand of multi- function small wireless devices, the antenna has to be compact, light and easy to be embedded with the system.

Antenna designer’s encountered difficulty in designing antennas that could maintain high performance; even the antenna size is smaller. In order to satisfy these demands, IFA has been widely used in mobile devices due to its low profile, ease of fabrication and superior electrical performance. At present the demand of WLANs are increasing numerously worldwide, because they provide high speed connectivity and easy access to networks without wiring.

Also in recent times the applications of WiMAX, which can provide a long operating range with a high data rate for mobile broadband wireless access, faultless internet access for wireless users becomes more popular [1-4]. On the other hand the RFID system has recently using effi- ciently for tracking and identifying objects in the various supply chains from security and control point of view [6- 7]. The fast growing WLAN protocals operating bands are IEEE 802.11 b/a/g at 2.4 GHz (frequency ranges 2400–2484 MHz), 5.2 GHz (frequency ranges 5150–5350 MHz) and 5.8 GHz (frequency ranges 5725–5825 MHz).

The operating bands of WiMAX are 2.5 (frequency ranges 2500 –2690), 3.5 (frequency ranges 3400–3600) and 5-GHz (frequency ranges 5250–5850 MHz) bands [1–5]. The frequency band used for the RFID system is 125 kHz; 13.56, 869 and 914 MHz; 2.45 and 5.8 GHz band [6-7]. There is a trend all over the world for the advance of compact, low- profile, multi-function antenna with the ability to support various commercial protocols [8]. For this reason compact antenna with suitable gain, low gain variation and satis- factory bandwidth for WLAN/WiMAX/RFID applications are extremely enviable.

A novel composite monopole antenna for 2.4/5.2/5.8 GHz WLAN and 2.5/3.5/5 GHz WiMAX operation in a laptop computer [1], a CPW-fed triangle-shaped monopole antenna for 2.4/5 GHz WLAN and 3.4 GHz WiMAX applications [2], a capacitively fed hybrid monopole/slot chip antenna for 2.5/3.5/5.5 GHz WiMAX operation in the mobile phone [3], a printed antenna with a quasi-self- complementary structure for 5.2/5.8 GHz WLAN operation [4], a novel dual-broadband T-shaped monopole antenna with dual shorted L-shaped strip-sleeves for 2.4/5.8 GHz WLAN operation [5], a simple coplanar waveguide (CPW)-fed patch antenna and a novel CPW-fed F-shaped planar monopole antenna obtained by embedding folded slots in a rectangular patch on a single-layer substrate for 5.8 GHz RFID application [6–7], a compact monopole an-

tenna for dual industrial, scientific and medical (ISM) band (2.4 and 5.8 GHz) operation [8], a novel wideband metal-plate antenna suitable for application as an internal laptop antenna for 2.4/5.2/5.8 GHz WLAN or 2.83–5.85 GHz WMAN operation [9], a printed antenna which is working in 2.4 GHz bluetooth, 3.5 and 5.8 GHz WiMAX, 2.4–2.5 and 5.0–5.8 GHz Wi-Fi, 2.4–2.84 GHz, 5.15–5.35 and 5.72–5.83 GHz WLAN operation [10], a broadband low-profile printed T-shaped monopole antenna for 5 GHz WLAN application [11] and a compact PIFA for

M

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 D. K. Karmokar, K. M. Morshed and Md. S. Hossain are with the Faculty of Electrical & Electronic Engineering, Khulna University of Engineering

& Technology (KUET), Khulna-9203, Bangladesh.

E-mail: debeee_kuet@yahoo.com.

 Md. A.Rahman is with the Department of Electrical & Electronic Engi- neering, IBAIS University, Dhaka, Bangladesh.

 M. N. Mollah is with the Department of Engineering & Technology, East- ern University, Dhaka, Bangladesh

Manuscript received on 21 July 2010 and accepted for publication on 26 August 2010.

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Bluetooth, satellite-digital multimedia broadcasting (S- DMB), wireless broadband (WiBro), WiMAX and WLAN applications [12] have been proposed. To provide the increasing demand and cover up the widespread applications of WLAN, WiMAX or RFID an antenna with compact size, wider bandwidth, high gain and less gain variation within the antenna bandwidth is desired. To meet up most of mentioned requirements, IFA is one of the good candidates within the micro-strip printed antennas because of its compact size and good input impedance than other printed antennas.

2 A

^NTENNA

D

^ESIGN

In designing the compact wideband antenna for WLAN, WiMAX and RFID operation, we examine the possibility of increasing antenna bandwidth with simplifying its structure. Using method of moments (MoM’s) in Numeri- cal Electromagnetic Code (NEC) [13], we conducted parameter studies to ascertain the effect of different loading on the antenna performance to find out the optimal design. In our analysis we assume the copper conductor and the antenna was intended to be matched to 50 Ω system impedance.

For the analysis of the accuracy optimum segmenta- tion of each geometrical parameter are used in NEC. Fig- ure 1 represents the basic geometry of the IFA. Here one leg of IFA directly connected to the feeding and another leg spaced s from the ground plane. For the simulation we consider printed circuit board (PCB) with permittivity of εr = 2.2 and substrate thickness of 1.58 mm.

The antenna is assumed to feed by 50 Ω coaxial con- nector, with its central conductor connected to the feeding point and its outer conductor connected to the ground plane just across the feeding point. In the analysis the (a)

(b)

(c)

Figure 1: Structure of Inverted-F Antenna (IFA) (a) 3-D front, (b) 3- D top and (c) 2-D view.

(c)

Figure 2: Structure of Double Inverted-F Antenna (DIFA) (a) 3-D front, (b) 3-D top and (c) 2-D view.

(a)

(b) Feed w

l t

h h1

s

Feed w

l t

h h1

h1

s d

(3)

dimensions of the ground plane considered as 60 × 60 mm². Figure 2 represents the modified IFA where load equal to the IFA is applied to the horizontal strip by shorting the end terminals is titled as double IFA (DIFA).

For IFA of Figure 1, the resonant frequency related to w given as [14]

(1)

Where c is the speed of light. The effective length of the current is l+t+h1+w. Under this case the resonant con- dition can be expressed as

(2)

The other resonant frequency that is a part of linear combination with the case 0<w< (1+t) and is expressed as

(3)

The resonant frequency (fr) is a linear combination of resonant frequency associated with the limiting case. For the antenna geometry of Figure 1, fr can be written from equation (1) and (2) as [15]

fr=r.f1+(1 -r)f2 (4)

Where r=w/(l+t). With the help of resonant frequency theory of IFA and impedance matching concept, we consider the dimension of the IFA as l=14 mm, t=6 mm, h1=4 mm, h=4 mm, s=0 mm, w=3 mm. Figure 3 (a) and (b) shows the effects of l and s on the antenna performance. From the simulated results, antenna has desired bandwidth at l=13 mm and s=1 mm. When l=14 or 15 mm, the values of return loss much better than l=13 mm but at that condi- tion antenna does not cover the whole 5 GHz operating band (frequency ranges 5150 – 5850 MHz) because our aim to design an antenna for 5 GHz operation so that it can cover the whole operating band. A higher value of l shifts the antenna resonance to the higher frequencies.

When s=0 mm the value of return loss stay above the 10 dB level throughout the 5 GHz band and when s=2 mm the antenna has very poor S11 characteristics. Figure 4 (a) and (b) shows the effects of t and w on the antenna performance. From the simulation, the optimum dimensions of IFA are l=13 mm, t=5 mm, h=4 mm, h1=3 mm, w=4 mm and s=1 mm.

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S11 (dB)

Frequency (GHz) l=11 mm

l=12 mm l=13 mm l=14 mm l=15 mm

(a)

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S 11 (dB)

Frequency (GHz) s=0 mm

s=1 mm s=2 mm

(b)

Figure 3: Effects of (a) length l and (b) spacing s on the return loss as a function of frequency on the antenna structure of Figure 1.

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S11 (dB)

Frequency (GHz)

t=4 mm t=5 mm t=6 mm t=7 mm

(a)

4 5 6 7 8

-15 -10 -5 0

S 11 (dB)

Frequency (GHz)

w=2 mm w=3 mm w=4 mm

(b)

Figure 4: Effects of (a) tap distance t and (b) width w on the return loss of the antenna of Figure 1 as a function of frequency.

) (

4 ₁

1 l t h f c



 

4

0 1

 



t h w l

) (

4 ₁

2 l t h w f c





 

(4)

When load is applied to the horizontal strip of IFA then the modified structure is shown in Figure 2 which titled as double IFA (DIFA). In this double IFA the structure of load is the same as source IFA. But the change made in separation d for the better performance. Figure 5 presents the characteristics of S11 as a function of frequency with different spacing s and separation d. From the obtained data, antenna provides better performance when d is set to 2 mm and s is to 1 mm. Variation of l and its effects on S11 for DIFA is shown in Figure 6. It is clear from the characteristics of S11, when l=12 mm the antenna provide good characteristics than l=13 mm but the bandwidth does not cover the whole 5 GHz band. For different values of t and w for the antenna of Figure 2, S11 are shown in Figure 7 (a) and (b) respectively. From the ob- served data proposed antenna cover the 5 GHz band, when t=5 mm and w=4 mm. When strip width is at w=3 mm, then the nature of S11 for the variation of l and t are

shown in Figure 8 (a) and (b). Moreover, at w=2 mm the characteristics of S11 are shown in Figure 9 (a) and (b) with the change in l and t. From Figure 8 and 9, when l=14 mm the DIFA has much better return loss characteristics than l=13or 15 mm. Also, the antenna has good S11

characteristics at l=15 mm when w=2 mm with respect to

l=13or 14 mm. But the problem is that, when w=2 or 3 mm, DIFA does not cover the whole 5 GHz band and resonance shifted to the frequency greater than 6 GHz.

Under these values of w (=2, 3 mm) with different values of t, antenna resonance shifts are not desired for the mentioned application. From Figure 5 to 9, in overall analysis, DIFA fully cover the 5 GHz WLAN operating band, when l=13 mm and w=4 mm. The optimized dimensions of the proposed DIFA are listed in Table 1.

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S 11 (dB)

Frequency (GHz)

d=0 mm d=2 mm d=4 mm

(a)

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S 11 (dB)

Frequency (GHz) s=0 mm

s=1 mm s=2 mm

(b)

Figure 5: Return loss as a function of frequency with the different (a) separation d and (b) spacing s of the antenna of Figure 2.

4 5 6 7 8

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S 11 (dB)

Frequency (GHz) t=4 mm

t=5 mm t=6 mm t=7 mm

(a)

4 5 6 7 8

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S 11 (dB)

l=12 mm l=13 mm l=14 mm l=15 mm

Figure 6: Effects of length l on the S11 as a function of frequency while t, h, h1 and w remains unchanged of the antenna of Figure 2.

TABLE1

OPTIMIZED DIMENSIONS OF THE PROPOSED ANTENNA

Antenna Name

Antenna Parameters

Value (mm)

Dimension (mm²)

DIFA

l 13

9×18

t 5

h 4

h1 3

d 2

w 4

s 1

(5)

3 N

UMERICAL

S

IMULATION

R

ESULTS

The proposed antenna is constructed and numerically analyzed using MoM’s. The numerical results of the antenna are shown below. The proposed antenna have the return loss appreciable than the commonly required 10 dB level. If we apply a suitable structured load equal to the IFA on the horizontal branch of IFA and shorted the ends of the both IFA as shown in Figure 2, the impedance bandwidth improves extensively. The numerical simulation analysis of the proposed DIFA to realize the operation for WLAN/WiMAX/RFID is presented below.

Figure 10 (a) shows the voltage standing wave ratio (VSWR) variation and Figure 10 (b) shows the return loss variation of DIFA with frequency. The DIFA provides a large impedance bandwidth of 2500 MHz (5000–7500 MHz) which fully covers the 5.2, 5.5 and 5.8 GHz bands and the peak value of return loss is -50.51082 dB. The value of VSWR of DIFA varies from 1.09877 to 1.61467 within the 5 GHz operating band that indicates the variation of VSWR is very low and it is near to 1 as shown in Figure 10 (a).

4 5 6 7 8

-60 -50 -40 -30 -20 -10 0

S 11 (dB)

Frequency (GHz) w=2 mm

w=3 mm w=4 mm

(b)

Figure 7: Return loss as a function of (a) tap distance t and (b) width w for the antenna of Figure 2.

4 5 6 7 8

-30 -25 -20 -15 -10 -5 0

S 11 (dB)

Frequency (GHz)

l=11 mm l=12 mm l=13 mm l=14 mm l=15 mm

(a)

4 5 6 7 8

-30 -25 -20 -15 -10 -5 0

S 11 (dB)

t=4 mm t=5 mm t=6 mm t=7 mm

(b)

Figure 9: Return loss as a function of (a) length l and (b) tap distance t for the antenna structure of Figure 2, when w=2 mm.

4 5 6 7 8

-50 -40 -30 -20 -10 0

S 11 (dB)

l=12 mm l=13 mm l=14 mm l=15 mm

(a)

4 5 6 7 8

-40 -30 -20 -10 0

S11 (dB)

t=5 mm t=6 mm t=7 mm

(b)

Figure 8: Return loss as a function of (a) length l and (b) tap distance t for the antenna structure of Figure 2, when w=3 mm.

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Figure 11 (a) shows the gain variation of DIFA. The peak gains of DIFA is 7.14, 7.11 and 6.50 dBi with less than 0.5, 0.7 and 0.6 dBi gain variation within the 10 dB return loss bandwidth at 5.2, 5.5 and 5.8 GHz band respectively, which indicates that the antenna has stable gain within the operating bandwidth which is desired for the wireless applications. Fig- ure 11 (b) represents the antenna input impedance variation and Figure 12 represents the antenna phase shift causes due the impedance mismatch as a function of frequency. From the obtained results, the input impedance of DIFA is near about 50 Ω which is desired for the impedance matching with the feeding system. Also, from the simulation study, within the return loss bandwidth, DIFA has phase shift closer to 0⁰ all over the antenna bandwidth except at the start of 5.2 GHz band, where phase shift closer to 30⁰. A comparison between the reference antennas and proposed DIFA in gain, bandwidth and size are listed in Table 2. In overall considerations, DIFA is much better than all other antennas. Figure 13 to 15 shows the normalized radiation patterns of DIFA at 5.2, 5.5 and 5.8 GHz bands respectively. The antenna’s normalized total radiation in H and E-plane is almost omnidirectional which is desired for the WLAN/WiMAX/RFID applications.

For the better analysis of the antenna, for three resonant fre-

quencies antenna’s normalized radiation patterns are shown as: total gain in H-plane, total gain in E-plane, horizontal gain in E-plane and vertical gain in H-plane.

4 5 6 7 8

0 2 4 6 8

Antenna Gain (dBi)

Frequency (GHz)

(a)

4 5 6 7 8

0 20 40 60 80 100

Input impedance (Ohm)

Frequency (GHz)

(b)

Figure 11: (a) Total gain and (b) Impedance variation of DIFA with frequency.

4 5 6 7 8

-90 -60 -30 0 30 60 90

Phase (degree)

Frequency (GHz)

Figure 12: Phase variation of DIFA with frequency.

4 5 6 7 8

0 1 2 3 4 5 6 7 8

VSWR

Frequency (GHz)

(a)

4 5 6 7 8

-60 -50 -40 -30 -20 -10 0

S11 (dB)

Frequency (GHz)

(b)

Figure 10: (a) VSWR and (b) Return loss variation of DIFA with frequency.

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(c) (d)

Figure 13: Radiation pattern (normalized) (a) Total gain in E-plane (b) total gain in H-plane (c) horizontal gain in E-plane and (d) vertical gain in H-plane of DIFA at 5.2 GHz.

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(c) (d)

TABLE2

GAIN,BANDWIDTH AND SIZE COMPARISON BETWEEN THE PROPOSED AND REFERENCE ANTENNAS

Antenna Peak Gain (dBi) Bandwidth

at 5 GHz Band

Dimension (mm²) 5.2 GHz

WLAN

5.5 GHz WiMAX

5.8 GHz WLAN/RFI

D

DIFA (Proposed) 7.14 7.11 6.50 2.5 GHz 9×18

Composite monopole antenna [1] 4.6 ~ 5.3 841 MHz 8×19.5

CPW-fed triangle-shaped monopole antenna [2] 3.59 - 3.05 3.1 GHz 25×34 Capacitively fed hybrid monopole/slot chip an-

tenna [3]

2.7-3.8 945 MHz 5.2×16

Printed antenna with a quasi-self-complementary structure [4]

3.3-4.0 - 3.2 ~ 3.8 1.462 GHz 6×21 T-shaped monopole antenna with dual Shorted

L-shaped strip-sleeves [5]

- 1.0 554 MHz 40×68

Simple coplanar waveguide (CPW)-fed patch antenna [6]

- - 2.9 ~ 4.7 490 MHz 15×10

Coplanar waveguide (CPW)-fed F-shaped planar monopole antenna [7]

- - 3.4 ~ 4.3 640 MHz 16.8×13

Compact monopole antenna [8] - - 2.105 330 MHz 4×30

Metal-plate antenna [9] 4.6 ~ 5.2 3.9 GHz 8.5×36

Printed antenna [10] 1.6 & 3.05

(H & E Plane)

3.07 & 4.67 (H & E Plane)

1.49 & 3.21 (H & E

Plane)

850 MHz 7.6×20

Low-profile printed T-shaped monopole antenna [11]

3.5 - 3.5 1.155 GHz 3×11

Compact PIFA [12] 4.95 at 6.3 GHz 2.53 GHz 8.2×24.3

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4 C

ONCLUSION

An optimized wideband double IFA for WLAN/WiMAX/RFID applications is proposed using numerical simulations. Effects of antenna geometry parameters are also presented here. The proposed antenna occupies a small area of 9×18 mm² with bandwidths of 2.5 GHz (5000MHz~7500MHz). Moreover the gain of the antenna is incredibly high and the gain variation of the antenna within the return loss bandwidth are very low at the required band means the antenna provides stable gain for the desired applications. From the analysis on the antenna’s gain, radiation pattern, return loss and input impedance is suitable for the specified applications then the antennas proposed earlier. Due to the compactness of the antenna, it is promising to be embedded within the dif-

ferent portable devices employing

WLAN/WiMAX/RFID applications.

REFERENCES

[1] K. -L. Wong and L. -C. Chou, “Internal Composite Monopole Antenna for WLAN/WiMAX Operation in A Laptop Computer,” Microwave and Optical Technology Letters, Vol. 48, No. 5, pp. 868-871, 2006.

[2] Y. Song, Y. -C. Jiao, G. Zhao and F. -S. Zhang, “Multiband CPW-Fed Triangle-Shaped Monopole Antenna for Wireless Applications,”

Progress in Electromagnetics Research, PIER 70, pp. 329–336, 2007.

[3] P. -Y. Lai and K. -L. Wong, “Capacitively Fed Hybrid Monopole/Slot Chip Antenna for 2.5/3.5/5.5 GHz WiMAX Operation in the Mobile Phone,” Microwave and Optical Technology Letters, Vol. 50, No. 10, pp.

2689-2694, 2008.

[4] K. -L. Wong, T. -Y. Wu, S. -W. Su and J. -W. Lai, “Broadband Printed Quasi-Self-Complementary Antenna for 5.2/5.8 GHz WLAN Opera- tion,” Microwave and Optical Technology Letters, Vol. 39, No. 6, pp. 495- 496, 2003.

[5] J. -W. Wu, Y. -D. Wang, H. -M. Hsiao and J. -H. Lu “T-Shaped Mono- pole Antenna with Shorted L-Shaped Strip-Sleeves for WLAN 2.4/5.8-

GHz Operation,” Microwave and Optical Technology Letters, Vol. 46, No.

1, pp. 65-69, 2005.

[6] W. -C. Liu, “A Coplanar Waveguide-Fed Folded-Slot Monopole An- tenna for 5.8 GHz Radio Frequency Identification Application,” Micro- wave and Optical Technology Letters, Vol. 49, No. 1, pp. 71-74, 2007.

[7] W. -C. Liu and C. -M. Wu, “CPW-Fed Shorted F-Shaped Monopole Antenna for 5.8-GHz RFID Application,” Microwave and Optical Tech- nology Letters, Vol. 48, No. 3, pp.573-575, 2006.

[8] J. Jung, H. Lee and Y. Lim, “Compact Monopole Antenna for Dual ISM- Bands (2.4 and 5.8 GHz) Operation,” Microwave and Optical Technology Letters, Vol. 51, No. 9, pp. 2227-2229, 2009.

[9] K. L. Wong and L. C. Chou, “Internal wideband metal-plate monopole antenna for laptop application,” Microwave and Optical Technology Letters, Vol. 46, No. 4, pp. 384–387, 2005.

[10] S. -Y. Sun, S. -Y. Huang and J. -S. Sun, “A Printed Multiband Antenna for Cellphone Applications,” Microwave and Optical Technology Letters, Vol. 51, No. 3, pp. 742-744, 2009.

[11] S. -W. Su, K. -L. Wong and H. -T. Chen, “Broadband Low-Profile Printed T-Shaped Monopole Antenna for 5-GHz WLAN Operation,”

Microwave and Optical Technology Letters, Vol. 42, No. 3, pp. 243-245, 2004.

[12] Y. -S. Shin and S. -O. Park “A novel compact PIFA for Wireless Communication applications,” IEEE Region 10 Conference 2007, pp. 1-3, 2007.

[13] G. J. Burke, and A. J. Poggio, “Numerical Electromagnetic Code-2,” Ver.

5.7.5, Arie Voors, 1981.

[14] M. –C. T. Huynh, “A Numerical and Experimental Investigation of Planar Inverted-F Antennas for Wireless Communication Applica- tions,” M.Sc. Thesis, Virginia Polytechnic Institute and State University, October 2000.

[15] K. Hirisawa and M. Haneishi, “Analysis, Design, and Measurement of small and Low-Profile Antennas,” Artech House, Boston, 1992.

Debabrata Kumar Karmokar was born in Satkhira, Bangladesh. He received the B. Sc.

in electrical & electronic engineering (EEE) from Khulna University of Engineering &

Technology (KUET), Khulna-9203, Bangla- desh, in 2007. He is currently working as a Lecturer in the same department of this university. He has authored or coauthored over 10 referred journal and conference papers.

His main interests include analysis and design of microstrip antennas, antennas for biomedical and RFID applications, antenna miniaturization, high gain microstrip antennas for satellite communications, power system, nano-particles and nano medicine. Mr. Karmokar is a member of Consultancy Research and Testing Services (CRTS), Dept. of EEE, KUET and a Member of Institute of Engineers Bangladesh (IEB).

Khaled Mahbub Morshed received Bache- lor of Science in electronics & communication engineering (ECE) with honors from Khulna University of Engineering & Technol- ogy, Khulna – 9203, Bangladesh, in 2007.

He is currently working as a Lecturer in the same department of this university. He authored and co-authored more than 18 publi- cations in refereed journals and conference proceedings in national and international level. His current research interests include analysis and design of microstrip/patch antennas, antennas for biomedical and RFID applications, antenna miniaturization, high gain microstrip antennas for satellite communications, eletromagnetics.

Mr. Morshed is a Member of Institute of Engineers Bangladesh (IEB), Life Member of Bangladesh Electronic Society (BES).

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(c) (d)

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Md. Selim Hossain was born in Kushtia, Bangladesh. He received the Bachelor of Science in electrical and electronic engineering (EEE) from Khulna University of Engineer- ing & Technology (KUET), Khulna-9203, Bangladesh, in 2008. He completed the SPACE (Saga University Programs for Academic Exchange) program from Saga University, Japan in 2007. He is currently working as a Lecturer in the same department of EEE, KUET. His research interests include analysis and design of Microstrip filter for microwave communication, measurement system, microstrip antennas, antennas for biomedical and RFID applications, antenna miniaturization. Mr. Hossain is a member of Consultancy Research and Testing Services (CRTS), KUET and an Assiociate Member of Institute of Engineers Bangla- desh (IEB).

Muhammad Aminur Rahman obtained his B.Sc. degree in electrical & electronic engineering from Khulna University of Engineer- ing & Technology (KUET), Bangladesh in 2009. In 2009, he joined in the department of electrical & electronic engineering of Interna- tional Business Administration and Informa- tion System University (IBAIS University), Dhaka, Bangladesh as a lecturer. His research interests include electromagnetic bandgap structures, microstrip patch antennas and also microwave engineering fields. He is an associate member of the Institution of Engineers Bangladesh.

Mohammad Nurunnabi Mollah was born in Jhenidah, Bangladesh, in 1964. He received the B.Sc. degree in electrical and electronic engineering from the Rajshahi University of Engineering & Technology (RUET) in 1986, the M.Sc. degree in electrical and electronic engineering from the Bangladesh University of Engineering and Technology (BUET) in 1997 and the Ph.D. degree from Nanayang Technological University (NTU), Singapore in 2005. In 1990, he joined the Department of Electrical and Electronic Engineering, Khulna University of Engineer- ing & Technology (KUET), Khulna, as a Lecturer and became a Pro- fessor in 2005. He is currently working as a Dean in the Faculty of Engineering and Technology of Eastern University, Dhaka, Bangla- desh. He has authored or coauthored over 45 referred journal and conference papers and one book chapter. His research interests include microstrip patch antennas and arrays, microwave passive devices and electromagnetic bandgap structures. Dr. Mollah is a Member of IEEE, USA and Fellow of the Institution of Engineers Bangladesh (IEB).