Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426

71 NITTTR, Chandigarh EDIT-2015

A Review of Multi Resonant Slotted Micro Strip Patch Antenna (MPA) for IMT, WLAN &

WiMAX Applications

Tejinder Kaur Gill, Ekambir Sidhu, Amarveer Singh

Abstract: In this paper, a stacked multi resonant slotted micro strip patch antenna (MPA) has been proposed which is suitable to be used for GSM, WLAN standard and WiMAX applications. The antenna has been designed using substrate of FR4 material. In the designed stacked antenna, substrates having different thickness has been used. The bottom stack of designed antenna has a radiating patch of circular shape and the patch on the upper stack has rectangular shape and is flexible in nature. The antenna has a feed line which is connected to circular patch to feed power to the antenna. The feed line has to be of suitable width to match the antenna impedance with port impedance of 50 ohms. The designed antenna has a defected ground structure in order to improve the antenna performance. The antenna performance has been measured in terms of antenna parameters such as impedance bandwidth (GHz), Return loss (dB), antenna impedance (ohms), VSWR and Directivity (dBi). The designed antenna results have been simulated in CST Microwave Studio 2010. The practically designed antenna has been tested successfully by using Network analyzer E5071C. It has been observed that the practical results closely match with theoretical results.[11]

Index Terms Micro strip patch antenna, Multi resonant air gap stacked antenna, Defected ground structure, Return loss (S11), Directivity, VSWR

I. INTRODUCTION1 Microstrip antenna, also known as printed circuit antenna or patch antenna is suitable for conformal and low profile applications. The Microstrip Patch Antenna has advantage of low cost and weight, design flexibility and ease of installation [4]. The radiating elements together with feed line are photo etched on a thin dielectric sheet on a ground plane. The patch can be square, rectangular or circular in shape. However, MPA suffers from disadvantage that they have narrow bandwidth. Extensive research has been carried out to overcome the band width problem in recent years and many techniques have been suggested and implemented to achieve the desired wide band characteristics [2][3]. One of these techniques is stacking antennas, realizing dual frequency operation with two resonant frequencies separated by certain range [8][9]. Stacked patch antenna is kind of microstrip which consists of two printed antenna. The lower patch is called driven patch and another patch is parasitically coupled to driven patch. To produce broadband responses the selection of the substrate of the first layer is very important. The current

distribution on the lower patch has an important role on the bandwidth of the antenna. If the lower dielectric layer has a greater dielectric constant than the upper layer, the magnitude of the first order mode on the lower patch will be greater than on the top patch thus the broadest bandwidths can be achieved. The thickness of each layer has an important role to obtain broader bandwidth. In the design process the lower patch does not design for minimum return loss in the desired band, rather than the patch should be strongly capacitive over this frequency range. To provide this, feed position of the antenna become near the edge of the patch. The adding of the second element moves the very capacitive impedance region of the single patch locus to near a matched condition [10]. The air gap can also be inserted between the two stacked layers as air gap provides maximum efficiency with minimum loss.

II. ANTENNA GEOMETERY

Fig 1 shows the top view of the bottom stack of the antenna. The Fig1 shows circular slotted patch excited by feedline of suitable width. Fig 2 represents the top view of upper substrate. Fig 3 represents the bottom view of stacked antenna. The ground has been

designed at the bottom of the lower stack which has been partially reduced. The antenna has been fabricated using FR4 as an substrate with dielectric constant of 4.4.The height of lower substrate is 1.57mm and that of upper substrate is 0.2mm.The feedline is designed in such a way that antenna will have 50 ohm resistance matched with the port impedance for maximum power transfer from port to patch. The dimensions of substrate, patch, feed, slots cut on patch and ground are listed in Table 2.

Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426

NITTTR, Chandigarh EDIT -2015 72

TABLE 2. ANTENNA PARAMETERS

Fig 1Top View of bottom stack of antenna

Fig 2 Top view of upper stack of antenna

Fig3 Bottom View of stacked antenna

NOTE:The dotted lines in Fig 3 represents the projection of patch and feedline on ground.

3. SIMULATED RESULTS The designed stacked antenna have been simulated using CST Microwave Studio 2010 and the performance of the antenna has been analyzed in terms of return loss, VSWR, radiation pattern, directivity, impedance and gain. The experimental results have been also obtained using E5071C ENA series Network Analyzer and it has been concluded that the practical results closely matches with the simulated theoretical results. Fig 4 represents the simulated results of return loss (S11) for designed stacked antenna. It has been observed that the return loss is -34.70 dB at 1.8086 GHz, -25.418 dB at 2.944 GHz, -21.32 dB at -3.2072 GHz, -20dB at 4.721 GHz and -30.774 dB at 5.310GHz. The simulated bandwidth of the proposed antennas is 2.62841 GHz.

Antenna Parameter Specification Length of substrate (Ls) 60mm Width of substrate (Ws) 60 mm

Radius of lower patch (R1) 18.8mm Radius of circular slot (R2) 10.8mm

Length of feed (Lp) 112mm Width of feed (Wp) 5.6mm

Length (L1) 22mm Length (L2) 21mm Length (L3) 20mm Width (W1) 13.2mm Width (W2) 5.6mm Width (W3) 4mm Width (W4) 2mm Width (W5) 2mm Width (W6) 2mm

Length of upper substrate (LUs) 30mm Width of upper substrate

(WUs) 30mm

Length of upper patch (LU1) 25mm Width of upper patch (WU1) 11.6mm

Length of ground (Lg1) 12mm Width of ground (Wg4) 60mm

Length of slot on ground (Lg5) 3mm Width of slot on ground (Wg5) 6.4mm

Length (LU2) 30mm Width (WU1) 24.2mm

Thickness of upper stack ( T1) 0.2mm Thickness of lower stack ( T2) 1.57mm

Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426

73 NITTTR, Chandigarh EDIT-2015

Fig 4 Return loss of stacked MPA

Fig 5 shows that value of VSWR for stacked MPA is less than 2 in the operating frequency range of 1.64 GHz to 1.965 GHz, 2.75 GHz to 3.46 GHz, 4.35 GHz to 6.03 GHz.

Fig 5 VSWR plot of stacked MPA

4. EXPERIMENTAL VERIFICATION The proposed antenna has been physically designed and the top and bottom view of practically designed antenna are shown in Fig 6(a) and Fig 6(b), respectively. The designs are tested using E5071C ENA series Network Analyzer. The practically analyzed results of slotted MPA are shown in Fig 7. It has been observed from Fig 7 that the practical results of designed MPA have return loss of -38.25 dB at 1.85 GHz, -28.35 dB at 3.15 GHz and -20.420 dB and -27.385 at 4.97 GHz and 5.427 GHz respectively. The bandwidth obtained from practical results of designed MPA is 3.14 GHz.

Fig 6 (a) Top view of designed stacked MPA

Fig 6(b) Bottom view of designed stacked MPA

Fig 7 Experimental result of stacked MPA

Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426

NITTTR, Chandigarh EDIT -2015 74

5. CONCLUSION From the above discussion, it can be concluded that the stacked microstrip patch antenna has bandwidth of 3.14 GHz with operating frequency range between 1.43GHz to 6.01 GHz .The VSWR for stacked microstrip patch antenna is less than 2 in the operating frequency range of 1.43 GHz to 6.01 GHz.

REFERENCES [1] http://www.internationaljournalssrg.org/IJECE/Volume5/IJ

ECE-V5N1P104.pdf. [2] J. R James., Hall P.S. and Wood C. Microstrip antenna

theory and design IEE Electromagnetic wave, Series 12 London, Peter Peregrinus1989.

[3] K.C Gupta. Recent advance in microstrip antenna. Micro wave Journal, vol-27, pp.50-67, 1984.

[4] J. l BahI & Bharta P., Microstrip Antennas, Massachusetts (USA) Artech House, 1980.

[5] Neha Ahuja, Study and investigations on various micro strip patch antennas for wireless applications, Thaper

University, http://dspace.thapar.edu:8080/dspace/bitstream/10266/1783/1/thesis.pdf.

[6] http://ieeexplore.ieee.org/Xplore/defdeny.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D5441102%26userType%3Dinst&denyReason=-134&arnumber=5441102&productsMatched=null&userType=inst

[7] http:en.wiki .edia.org/wiki/WiMax/Wlan.S.A Long & Walton M.D, A Dual-frequency circular-disc antenna, IEEE Trans. Antenna & Propag (USA), AP-27, and pp.270-273, 1979.

[8] T.M Au and K M Luk, Effect of parasitic element on the characteristics of microstrip antenna, IEEE Trans Antenna & Propaga tion(USA) AP- 39,pp.1247-1251, 1991.

[9] http://www.ursi.org/proceedings/procGA11/ursi/AB2-4.pdf.

[10] http://en.wikipedia.org/wiki/GSM_frequency_bands. [11] file:///C:/Users/good/Downloads/IJARCET-VOL-3-ISSUE-

10-3577-3585.pdf

Front.pdfFinal Vol 1.pdfFront.pdf