Rectaangular Microstrip Patch Antenna For Wireless


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International Journal of Scientific & Engineering Research, Volume 5, Issue 3, March-2014

990

ISSN 2229-5518

Rectangular Microstrip Patch Antenna for
Wireless Communications at 6.5 GHz
Ms. Neha Patel1, Prof.Jaikaran singh2, Prof.Mukesh Tiwari3
Abstract—Due to the existence of growth in development of low cost, less weight, highly reliable, minimal profile antennas for wireless devices, it poses a new challenge for the design of antenna in wireless communications. This paper presents design and simulation of a rectangular microstrip patch antenna at 6.5 GHz for wireless communications. This antenna has 140 MHZ bandwidth, Return loss at centre frequency has less than -16.70dB. The beauty of this antenna is the use of single patch which make it easy to fabricate consequently cost of antenna becomes cheaper. The rectangular microstrip patch antenna is analyzed using High Frequency Structure simulator (HFSS) v 11.

Keywords: Rectangular Microstrip Patch Antenna, Return Loss, VSW R, Bandwidth, High Frequency Structure simulator (HFSS) v 11, Wireless communication.

1. INTRODUCTION

Microstrip patch antennas have drawn the attention of

researchers over the past few decades. However, the antennas

inherent narrow bandwidth and low gain is one of their major

drawbacks [1, 2]. This is one of the problems that researchers

around the world have been trying to overcome. Throughout

the years, authors have dedicated their investigations to

creating new designs or variations to the original antenna that,

IJSER to some extent, produce wider bandwidths. The patch antenna has been rapidly used in various fields like space technology, aircrafts, missiles, mobile communication, GPS system, and broadcasting. Patch antennas are light in weight, small size, low cost, simplicity of manufacture and easy integration to circuits. More important is these can be made out into various shapes like rectangular, triangular, circular, square etc [1].
Many techniques have been suggested for achieving the high bandwidth. These techniques includes: using parasitic elements either in same or other layer [7], utilization of thick substrates with low dielectric constant [4], and slotted patch [5]. We have used a thick dielectric substrate having a low dielectric constant which provides better efficiency, larger bandwidth and better radiation. However, such a configuration leads to a larger antenna size. In order to design a compact Microstrip patch antenna, higher dielectric constants must be used which are less efficient and result in narrower bandwidth. Hence a compromise must be reached

Figure1. Microstrip Patch Antenna
The patch is generally made of conducting material such as copper or gold and can take any possible shape. The radiating patch and the feed lines are usually photo etched on the dielectric substrate [1, 3]. The patch is selected to be very thin such that t << λo (where t is the patch thickness). The height h of the dielectric substrate is usually 0.003 λo ≤ h ≤ 0.05λo. The dielectric constant of the substrate (εr) is typically in the range 2.2 ≤ εr≤ 12 r. Microstrip patch antennas are increasing in popularity for use in wireless applications due to their lowprofile structure. Therefore they are extremely compatible for embedded antennas in hand-held wireless devices such as cellular phones, pagers etc. The telemetry and communication antennas on missiles need to be thin and conformal and are often Microstrip patch antennas. Another area where they have been used successfully is in Satellite communication.

between antenna dimensions and antenna performance.

3. FEED TECHNIQUE

2. MICROSTRIP PATCH ANTENNA
Microstrip patch antenna consists of a radiating patch on one side of a dielectric substrate which has a ground plane on the other side as shown in Figure 1.

Microstrip patch antennas can be fed by a variety of methods [1, 2]. These methods can be classified into two categories- contacting and non-contacting. In the contacting method, the RF power is fed directly to the radiating patch using a connecting element such as a Microstrip line. In the

————————————————
• Ms .Neha Patel: M.Tech Scholar (Digital Comm.), SSSIST, Sehore (M.P) India

non-contacting scheme, electromagnetic field coupling is done to transfer power between the microstrip line and the radiating patch. The four most popular feed techniques used

• Prof.Jaikaran singh, Prof.Mukesh Tiwari: Assoc. Professor, ECE, SSSIST, Sehore (M.P)

are the Microstrip line (fig.2), coaxial probe (fig.3) (both contacting schemes), aperture coupling and proximity

coupling (both non-contacting schemes).This paper uses

microstrip line feeding technique.

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International Journal of Scientific & Engineering Research, Volume 5, Issue 3, March-2014

991

ISSN 2229-5518

4.1 Transmission Line Model
This model represents the microstrip antenna by two slots of width W and height h separated by a transmission line of length L. The microstrip is essentially a non homogeneous line of two dielectrics, typically the substrate and air. The formulas used in this model for calculation of the dimensions are discussed in next section.

Figure 2. Microstrip Line Feed

Figure4. Microstrip Line

IJSERFigure5. Electric Field Lines 5. MICROSTRIP RECTANGULAR PATCH ANTENNA DESIGN

Figure3. Coaxial Feed
4. METHOD OF ANALYSIS

Design of microstrip patch antenna depends mainly upon three parameters, namely substrate and its dielectric constant, height of the substrate and resonant frequency. In this paper, selected three parameters are: Resonant Frequency (fr) = 6.5 GHz, Dielectric constant (εr) = 4.5, Height of the dielectric substrate (h) = 1.50 mm.

The most popular models for the analysis of Microstrip patch antennas are the transmission line model, cavity model, and full wave model (which include primarily integral equations/Moment Method) [1,3]. The transmission line model is the simplest of all and it gives good physical insight, but it is less accurate. The cavity model is more accurate and gives good physical insight but is complex in nature. The full wave models are extremely accurate, versatile and can treat single elements, finite and infinite arrays, stacked elements, arbitrary shaped elements and coupling. These give less insight as compared to the two models mentioned above and are far more complex in nature. In this paper Transmission line model is used for designing the patch antenna.

Figure6. Represent design of Microstrip Rectangular Patch antenna.

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INTERNATIONAL JOURNAL OF SCIENTIFIC & ENGINEERING RESEARCH, VOLUME 5, ISSUE 3, MARCH-2014

992

ISSN 2229-5518

5.1 Calculation of the width (W): The width of the Microstrip patch antenna is given by equation (1) [1, 2]:
5.2 Calculation of Effective dielectric constant (Ԑeff):

It integrates simulation, visualization, solid modeling, and automation in an easy-to-learn environment where solutions to your 3D EM problems are quickly and accurately obtained. Ansoft HFSS employs the Finite Element Method (FEM), adaptive meshing, and brilliant graphics to give you unparalleled performance and insight to all of your 3D EM problems. Ansoft HFSS can be used to calculate parameters such as S-Parameters, Resonant Frequency, and Fields [6].
7. SIMULATION RESULTS
The Microstrip Rectangular patch antenna is simulated using Ansoft HFSS. The parameters evaluated were Return loss, VSWR, Radiation pattern, Directivity, Gain, 3D polar plot.

5.3 Calculation of the Effective length (Leff):

Figure7.1 Return loss for Rectangular patch antenna

Leff = c / 2 f 0 ξ reff

5.4 Calculation of the Length Extension (ΔL):
IJSER 5.5 Calculation of the resonant length of patch (L):

L = Leff – 2 ΔL Table 1: Dimensions of patch antenna

Figure7.2 VSWR for Rectangular patch antenna

Resonating frequency fr Patch Width W Patch Length L Branch line length qw Substrate height H Relative permittivity Ԑr Feed line length Feed line width

6.5GHZ 24mm 22mm 24.05mm 1.50mm 4.4 15mm 2.75mm

6. SOFTWARE TOOL
The software used to model and simulate the microstrip patch antenna is HFSS. HFSS is a high-performance fullwave electromagnetic (EM) field simulator for arbitrary 3D volumetric passive device modeling that takes advantage of the familiar Microsoft Windows graphical user interface.
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INTERNATIONAL JOURNAL OF SCIENTIFIC & ENGINEERING RESEARCH, VOLUME 5, ISSUE 3, MARCH-2014

993

ISSN 2229-5518

Figure7.3 Radiation Pattern for Rectangular patch antenna

Figure7.4 Directivity for Rectangular patch antenna

Table 2: The results of Microstrip rectangular patch

antenna

Parameters

Rectangular patch

Resonant frequency

6.5GHz

Bandwidth

140MHz

Return loss(dB)

-16.70

VSWR

1.34

Gain(dB)

2.65

IJSER Directivity(dB)

6.24

8. CONCLUSION AND FUTURE SCOPE
Thus the design and simulation of Microstrip rectangular patch antenna was successfully designed and analyzed using Ansoft HFSS. The performance parameters were achieved with Return loss -16.70dB, gain 2.65 dB and

bandwidth 140 MHz for rectangular patch antenna. The use

Figure7.5 Gain for Rectangular patch antenna

of slotted patch reduces the size of antenna and higher

bandwidth, which is the area that can be improved with the

proposed design.

Figure7.6 3D polar plot for Rectangular patch antenna

9. REFERENCES
[1] J Constantine A. Balanis; Antenna Theory, Analysis and Design, John Wiley & Sons Inc. 2nd edition. 1997. [2] Garg, R and Ittipiboon, A; “Micro strip Antenna Design Handbook”, Artech House, 2001. [3] D.M. Pozar, ―Microstrip Antennas, Proc.IEEE, vol.80, No.1, January 1992. [4] Neeraj Rao, Gain and Bandwidth Enhancement of a Microstrip Antenna using Partial substrate removal in multiple layer dielectric substrate, PIER proceedings, Suzhou, China, Sept.12-16, 2011. [5] Isha Puri, Bandwidth and Gain increment of microstrip patch Antenna with Shifted elliptic‖al , SIlJoEtST , vol.3No.7, July, 2011. [6] www.AnsoftHFSS.com [7] Wood.C, Improved Bandwidth of Microstrip Antenna using parasitic elements, IEEE vol.127, Issue4, 11Nov, 2008, pp.-231-234

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Rectaangular Microstrip Patch Antenna For Wireless