Ultra Wideband Miniature Microstrip Patch Antenna with Defected Ground Notches

Ultra Wideband Miniature Microstrip Patch Antenna with Defected Ground Notches

Dana Saeed Muhammad Asaad M. J. Al-Hindawi

M .SC. Student in Physic department, Ass. Professor in Communication Eng. Dept. School of Science, Sulaimani University Technical College of Engineering,

Sulaimani Polytechnic University

Abstract – The defected ground notches DGN for microstrip patch antenna and its effects on antenna performance have been studied using HFSS simulator. Different patch shapes: square, triangular-rectangular and circular have been supposed. The DGN has been suggested by reducing the length of antenna ground plane and making different shapes of notches at the edges of the proposed ground. The obtained results indicates that the antenna ground of length reduction with three, one and three notches gives respectively an impedance bandwidth from 3.42-17.45 GHz (134% w.r.to centre frequency), 2.33-14.63 GHz (145%) and 3.31-16.13 GHz (131%) for square, triangular-rectangular and circular patches. Also a size reduction of 83.5%, for square and circular patches and 82.5% for triangular-rectangular patch are achieved at resonance frequency of 4.05 GHz and 4.5 GHz respectively compared with those antennas having the same design and operating at the same resonance frequencies but without DGN.

1. INTRODUCTION

   Wireless communications have been developed widely and rapidly in the modern world especially during the last two decades. The development of the personal communication devices will aim to provide image, speech and data communications at any time, and anywhere around the world. This indicates that the communication terminal antennas must meet the requirements of wideband to sufficiently cover the possible operating frequencies. In addition, for miniaturizing the wireless communication system, the antenna must also be small enough to be placed inside the system, low weight, low profile, and low cost. Microstrip patch antennas are widely used to provide and achieve these requirements except the limitation of narrow impedance-bandwidth. Therefore, bandwidth enhancement is currently a popular research area for microstrip antennas in order to transmit and receive more information.

   Tugonski, et al.[1] presented a technique which extends the operating bandwidth of the aperture coupled microstrip antenna to over 50%. On the antenna side of the ground plane, a thick slab of Rogers 5880 Duroid is used for the lower substrate, while foam is used for the top substrate.

   connected ground plane inside the rectangular slot, it is easily fabricated and BW percentage was 52%. Another technique to increase BW was published by Hongyu with partner [3]. It was shown that by using two 180 degrees out of phase excited cylindrical probes, the bandwidth of a patch antenna can be dramatically increased. Based on the proposed differential cylindrical probes (DCP) feed, they were designed a square patch antenna with 104% impedance bandwidth. In 2013 Chattopadhyay et al. [4], proposed and experimentally investigated a wideband microstrip-line-fed hexagonal wide-slot antenna.The hexagonal slot excited by a simple 50 microstrip line with a rotation angle of 0° having 470 MHz bandwidth is considered as a reference antenna. The proposed hexagonal slot is rotated by 30° and excited by a 50 line loaded by a hexagonal tuning stub. The experimental results exhibit matching impedance below a 2:1 VSWR bandwidth of 5165 MHz (2.1177.282 GHz) covering all the WiMAX and wireless local area network band applications, the percentage impedance bandwidth out 110% at centre frequency of 4699.5 MHz.

   The present paper aims to enhance the bandwidth and to miniaturize the antenna size using simple two dimensional structure.

2. ANTENNA DESIGN

   Three different antenna designs are investigated. The design configurations for square patch, triangular- rectangular patch and circular patch are illustrated in Fig.1a,b,and c respectively. The ground plane of these antennas is defected by reducing its length and making different shapes of notches at the medium, right and left edges of the defected ground structure as shown in Fig.1. The dimensions of these antennas are listed in Table 1 where × , × and × are respectively the dimensions of patch, substrate and ground plane.

   Ws Wp

   The top patch was etched on a 5 mil thick 5880 Duroid

   cover layer. Another paper has been published in 2005 by Korean researchers [2] who designed a rectangular slot antenna fed by T-shaped microstrip line for achieving both harmonic suppression and wide bandwidth. Since this proposed antenna consists of the U-shaped conductor line

   Lnl

   Ls

   Wnl

   Wf

   Lf

   Wnm

   Wg

   Lnm

   Lp

   Wnr

   h

   Lnr

   Lg

   Fig.1a: Design of square patch antenna with three DGNs.

   a Ws

   Ls

   Wp

   Wf L

   Table 2: Dimensions of defected ground notches in mm

   Lf

   Wnm

   Wg

   p

   L Lnm

   Lg

   Antenna patch	Left notch ×	Medium notch ×	Right notch ×
   Square	2 × 4	4 × 4	1 × 5
   Train.-rect.	–	6 × 4	–
   Circular	1 × 4	6 × 4	1 × 4

3. ANTENNA SIMULATION AND RESULTS

   The proposed antenna designs are analysed and simulated using high frequency structure simulator (HFSS), commercial computer software package from Ansoft Technologies, which is based on the finite element method

   Lnl

   Fig.1b: Design of train.-rect. patch antenna with one DGN.

   Ls Ws

   a

   W

   Wnl

   f

   (FEM) technique for arbitrary 3D volumetric passive devices [5]. The characteristics of impedance bandwidth are examined for those three antennas. The return loss, VSWR and radiation patterns of the studied antennas are obtained. Fig.2 shows the return loss S11 characteristics of the square, triangular-rectangular and circular patch antennas for the frequency band of 1-30 GHz. The bandwidth of the square, triangular-rectangular and circular patch antennas are respectively from 3.42-17.45 GHz (percentage of 134% w.r.to centre frequency), 2.33-14.63

   Lf

   Wnm

   Wg

   Lnm

   Wnr

   Lg

   Lnr

   GHz (145%) and 3.31-16.13 GHz (131%). The VSWR

   curves for the studied antennas are plotted in Fig.3.

   Fig.1c: Design of circular patch antenna with three DGNs.

   Table 1: The dimensions of studied antennas in mm.

   Patch shape	Patch ×	Substrate ×	Ground ×
   Square	14 × 14	28 × 30	10.5 × 30
   Train.-rect.	9 × 14 = 10	28 × 30	10.5 × 30
   Circular	= 8	28 × 30	10.5 × 30

   The dimensions of defected ground notches are given in Table 2 for left notch × , medium notch ×

   and right notch × . It is noted that the medium notch is shifted to the right side by 4mm for all

   antenna designs.

   The dimensions of strip line feed for all antennas are ×

   = 11.5 × 4.8 2. The substrate material is proposed to be Duroid material of dielectric constan =2.2 and its thickness is 1.57mm.

   —– Square

   —– Triang.-Rect.

   —– Circular

   Fig.2: The characteristics of return loss for square, tarin.-rect, and circular patch antennas.

   —– Square

   —– Tria/Rect.

   —– Circular

   Fig.3: VSWR properties for square, tarin.-rect, and circular patch antennas.

   Table 3: Summary of the obtained results

   Antenna	GHz	11	VSWR	%
   Square	4.05	-19.35	1.24	134
   Train-rect.	4.5	-29.61	1.06	145
   Circular	4.05	-25.22	1.11	131
   Hexagonal slot [4]	3.35	-21	1.2	110

   Table 3 summarizes the obtained results for the investigated antennas compared with hexagonal slot antenna [4].

   The radiation characteristics of the proposed antennas are given in Figs. 4-6. The E- and H-plane patterns of square,

   (b)

   Fig.5: (a) E- and H- plane radiation patterns of train.-rect. patch antenna with DGN. (b) 3D gain radiation pattern of train.-rect. patch antenna with DGN.

   traing.-rect. and circular patch antennas are illustrated in Figs.4a, 5a and 6a respectively while Fig.4-6b shows 3D radiation pattern of the studied antennas.

   .

   0

   -60

   -30

   . .

   0

   30

   1.20

   -1.60

   60

   -4.40

   -90

   -60

   -120

   -30

   1.00

   -3.00

   -7.00

   -11.00

   30

   60

   120

   90

   —E-plane

   —H-plane

   -90

   -120

   -150

   -7.20

   -180

   (a)

   150

   120

   90

   —E-plane

   —H-plane

   -150

   -180

   (a)

   150

   (b)

   Fig.4: (a) E- and H- plane radiation patterns of square patch antenna with DGNs. (b) 3D gain radiation pat.tern of square patch antenna with DGNs.

   (b)

   Fig.6: (a) E- and H- plane radiation patterns of circular patch antenna with DGNs. b) 3D gain radiation pattern of circular patch antenna with defected ground notches.

   Table 4: Comparison between the studied antennas and hexagonal slot antenna [4].

   -90

   -60

   -30

   0

   Antenna, size 3	GHz	VSWR	%	Gain dB
   Square 28 × 30 × 1.57	4.05	1.24	134%	2.89
   Train-rect. 28 × 30 × 1.57	4.5	1.06	145%	3.07
   Circular 28 × 30 × 1.57	4.05	1.11	131%	2.85
   Hexagonal slot 110 × 110 × 1.57 [4]	3.35	1.2	110%	5.6

   30

   1.50

   -2.00

   60

   -5.50

   -9.00

   90

   -120

   -150

   -180

   (a)

   150

   120 —E-plane

   —H-plane

   It is clear that the studied antennas with defected ground notches behave as omnidirectional antennas, and their gain decreases to about 3dB.

4. RESULTS ANALYSIS

   1. The improvement in bandwidth and reduction in antenna size are achieved as indicated in Table 4 and the antennas properties are compared with those for hexagonal slot antenna [4].

   2. Size reduction

      The sizes of the studied antennas with defected ground notches are compared with the sizes of antennas having the same design and same resonance frequency but without defected ground notches (normal ground) as given in Table

5. It is clear that a reduction in antenna size of 83.5% and 82.4% are achieved for square, circular and triangular- rectangular patches respectively.

Table 5: Comparison between sizes of studied antennas and those of antennas having same design and resonance frequency

—– Square

—–Tria/Rec.

—– Circular

Fig.7: The characteristics of return loss for square, tarin.-rect, and circular patch antennas without DGN.

1. Resonance frequency

The antenna designs proposed in Fig.1 are again investigated but with normal ground plane (without DGN) and the return loss characteristics is plotted in Fig.7. The obtained resonance frequencies of these antennas are compared with those of antennas with DGN as given in Table 6. The relationship of these resonance frequencies may expressed as:

0.3 for square and circular patches, and 0.17 for triangular-rectangular patch, where is the resonance frequency of antenna with defected ground notch (DGN) while is the resonance frequency of antenna with normal ground (without DGN).

Table 6: Comparison betweeesonance frequencies of antennas without DGN and with those of antennas with DGN.

4. CONCLUSIONS

Different patch shapes (square, triangular-rectangular and circular) have been proposed. The DGN has been made by reducing the ground length and making different shapes of notches at the edges of the studied ground. Impedance bandwidth enhancement and antenna size miniaturization have been achieved. These antennas are promising to be embedded within Wi-Fi, WLAN, WiMax applications and also, could be used in on-board satellite because of its small size compared with the others.

REFERENCES

1. S. D. Tugonski, and R. B. Waterhouse, An Aperture Coupled Stacked Patch Antenna with 50% Bandwidth, Antennas and Propagation Society International Symposium, AP-S. Digest. IEEE, 1:18-21. 1996

2. D. H. Choi, Y. J. Cho, and S. O. Park , A broadband T-shaped Microstrip-line- Fed Slot Antenna with Harmonic Suppression, Microwave Conference Proceedings, APMC. Asia-Pacific Conference Proceedings. IEEE, 4, 2005.

3. N. Prombutr, P. Kirawanich, and P. Akkaraekthalin, Bandwidth Enhancement of UWB Microstrip Antenna with a Modied Ground Plane.", International Journal of Microwave Science and Technology: 1-7. 2009.

4. K. Chattopadhyay, S. R. Choudhury, S. Das, S. R. Bhadra, Wideband Microstrip-line-Fed Hexagonal Slot Antenna for WiMAX and Wireless Local Area Network Applications, J Eng, 10:1-3. 2013.

5. Kunal Parikh, Simulation of Rectangular, Singl Layer, Coax-Fed patch Antennas Using Agilent High Frequency Structure Simulator (HFSS), M.Sc. Thesis, submitted to the Faculty of the Virginia Polytechnic Institute and State University, 2003.

BIOGRAPHY

.

Dana Saeed has received his B.Sc. in Physics (2007) from the College of Science- University of Sulaimani, Sulaimani, Iraq. currently he is M.Sc. student in Department of Physics , college of Science, University of Sulaimani, Sulaymaniyah, Kurdistan Region, Iraq.

Dr. Asaad Al-Hindawi earned his B.Sc. in electrical Engineering from the University of Baghdad, Baghdad, Iraq. In addition, he received M.Sc. in communication engineering from the University of Technology, Baghdad, Iraq and a Ph. D. in Radio & communication engineering, from Varna Technical University, Varna, Bulgaria. Currently he is an Assistant Professor in Communication Engineering Department, Technical College of Engineering,

Sulaimani Polytechnic University, Sulaymaniyah, Kurdistan Region, Iraq