Available ONLINE www.vsrdjournals.com

VSRD-IJEECE, Vol. 2 (4), 2012, 160-167

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1,3Research Scholar, 2Assistant Professor, 1,2,3Department of Electronics Technology, Guru Nanak Dev University, Amritsar, Punjab, INDIA. *Correspondence : atinder_mehal@yahoo.com

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Design of Edge Fed Rectangular Microstrip Patch Antenna for WLAN Applications

Using Ansoft-HFSS 1Atinder Pal Singh*, 2Ravinder Kumar and 3Hartej Singh Dadhwal

ABSTRACT

As of today, Wi-Fi (also known as WLAN) has become a standard in most computers. Almost every modern

mobile phone and other gadgets are being implemented with Wi-Fi technology. Wi-Fi makes it possible for the

user to connect to the internet or LAN (Local Area Network) though a wireless connection hence its other name

is WLAN. WLAN uses the technical term “IEEE 802.11” and has standards in the names of 802.11 b/g/n.

Microstrip Patch Antennas have been widely used in a various useful applications, due to their low weight and

low profile, conformability, easy and cheap realization. In this paper, an attempt has been made to design Edge

Fed Microstrip antenna structure for WLAN systems at 2.4835 GHz Frequency Using Ansoft-HFSS v13.

Keywords : Edge Fed Rectangular Patch Antenna, WLAN, Rogers RT/Duriod 5870 Substrate, HFSS v13.

1. INTRODUCTION

An antenna is a device used to transform an RF signal, travelling on a conductor, into an electromagnetic wave

in free space. Antennas demonstrate a property known as reciprocity, it means that an antenna will maintain the

same characteristics regardless if it is transmitting or

receiving. Most of the antennas are resonant devices, which

operate efficiently over a relatively narrow frequency band.

A Microstrip antenna consists of a metallic pattern on one

side of a dielectric substrate and ground plane on the other

side of the substrate. The antenna patch can have different

shapes, but is most likely rectangular.aaaaaaaaaaaaaaa

Fig. 1 : Structure of Rectangular Microstrip Patch Antenna

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2. VARIOUS SUBSTRATE MATERIALS

2.1. Ceramic Substrate

The ceramic substrate is mainly used in small size applications with frequencies below 1 GHz. It has low a loss

tangent and has good chemical resistance, but is also very expensive. Besides that, ceramic is very hard to

produce and handle. For instance it is very hard to drill holes in the substrate without breaking it. Some ceramic

material has a high dielectric constant which is used where you need an important size reduction.

2.2. Synthetic Substrate

Synthetic substrate is commonly made out of organic material like PTFE (also known as Teflon). These

materials possess low loss tangent and low Er. The only problem is that this material is very soft and can

therefore easily change the characteristics of a microstrip antenna if it is not handled well enough.

2.3. Composite Material Substrate

Composite material is made out of mixed chemicals between fibreglass, ceramic or quartz and synthetic

material. There is a wide variety of composite material on the market which has been modified so they fit both

to antenna fabrication and standard PCB design.

2.4. Low-Cost Low-Loss Substrate

Ceramic, Synthetic and Composite material substrate is usually used where other applications are needed or a

microstrip antenna needs perfection and also it is too expensive to use in consumer electronics such as TV’s,

mobile phones, etc.

3. RESEARCH METHODOLOGY

In order to make performance predictions the rectangular patch antenna has the following parameters, where λ0

is the wavelength in vacuum also called the free-space wavelength.

• Length (L) : 0.3333λ0 < L < 0.5λ0

• Height (h) : 0.003λ0 ≤ h ≤ 0.05λ0

• Thickness (t ) : t << λ0

• Dielectric constant (εr ) : 2.2 ≤ ε r ≤ 12

HFSS (High Frequency Structure Simulator) software is the industry-standard simulation tool for 3-D full-wave

electromagnetic field simulation and is essential for the design of high-frequency and high-speed component

design. This software automatically divides the geometric model into a large number of tetrahedron, where a

single tetrahedron is a four-sided pyramid. This collection of tetrahedron is referred to as the finite element

mesh. Each element can contain a different material. Therefore, the interface between two different materials

must coincide with element boundaries. The value of a vector field quantity (such as the H-field or E-field) at

points inside each tetrahedron is interpolated from the vertices of the tetrahedron. By representing field

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quantities in this way, the system can transform Maxwell's equations into matrix equations that are solved using

traditional numerical methods. With HFSS, engineers can extract scattering matrix parameters (S, Y, Z

parameters); visualize 3-D electromagnetic fields (near- and far-field). Each HFSS solver is based on a

powerful, automated solution process where you are only required to specify geometry, material properties and

the desired output. From there HFSS will automatically generate an appropriate, efficient and accurate mesh for

solving the problem using the selected solution technology. The Comparison among various antenna software

packages and their principle of operation are given in the form of table at the end.

4. DATA ANALYSIS

The rectangular patch antenna is approximately one-half wavelength long section of rectangular microstrip

transmission line. When air is the antenna substrate, the length of the rectangular microstrip antenna is

approximately one-half of a free-space wavelength. As the antenna is loaded with a dielectric as its substrate, the

length of the antenna decreases as the relative dielectric constant of the substrate increases. The resonant length

of the antenna is slightly shorter because of the extended electric "fringing fields" which increase the electrical

length of the antenna slightly. In our paper we taken the Substrate material as Rogers RT/Duriod 5870(tm) with

relative permittivity = 2.33, Dielectric Loss Tangent = 0.0012 and Lande G factor = 2. Its low dielectric

constant, low loss tangent and low cost make it a first choice material for microwave substrate. The figure below

shows the various terminologies associated with Edge Fed Microstrip Patch Antenna.

Fig. 2 : Terminology of Edge Fed Microstrip Patch Antenna

There are various theories that can be used in analysis and design of rectangular microstrip patch antennas like

Cavity model, Transmission Line model etc. We have used Transmission Line model here. According to this

model, rectangular patch is viewed as very wide transmission line that is transversely resonating, with the

electric field is varying sinusoidal under the patch along its resonant length. Various Formulae for calculating

the Dimension parameters of Rectangular Microstrip Patch antenna using this model are:

Effective Dielectric Constant :

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Width of the patch:

Due to Fringing fields, the change in dimensions of length is given by:

Effective Length of the patch:

The various design parameters of Edge fed Rectangular patch Antenna are calculated at frequency 2.4835 GHz.

The various parameters are: Patch dimension along x = 4.77cm, Patch dimension along y = 3.99cm, Substrate

Dimension along x = 8.1cm, Substrate dimension along y = 16.67cm, Edge feed width = 0.189cm, Edge feed

length = 2.263cm, Feed Width = 0.485cm, Feed Length = 3.679cm. These parameters are used by the Ansoft-

HFSS to generate the corresponding design of Edge fed rectangular Microstrip patch antenna which is shown in

fig.3.

Fig. 3 : Ansoft-HFSS Generated Edge Fed Patch Antenna

5. EXPERIMENTAL RESULTS

The various Antenna Parameters are calculated by using Ansoft-HFSS and the simulated results are shown

below:

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5.1. Return Loss

Fig. 4 : Return Loss v/s Frequency Curve

5.2. Far Field Radiation Patterns

Fig. 5(a) : Radiation Pattern showing Total Gain

Fig. 5(b) : Radiation Pattern Showing Total Gain at Phi = 0 & 90 degree

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5.3. 2-D Radiation Pattern

Fig. 6(a) : 2-D Total Gain Plot

Fig. 6(b) : 2-D Gain at Phi = 0 & 90 degree

5.4. 3-D Polar Plot

Fig. 7 : 3-D Polar Plot showing Total Gain (in db)

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5.5. Field Distributions

Fig. 8(a) : E-Field Distribution

Fig. 8(b) : H-Field Distribution

Fig. 8(c) : Mesh Pattern of Edge Fed Patch Antenna

Mesh Generation is the practice of generating a polygonal or polyhedral mesh that approximates a geometric

domain to the highest possible degree of accuracy. The triangles show the current distribution. Here the number

of triangles on the substrate is more than on patch thus indicating the current distribution in the substrate is more

than patch.

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6. CONCLUSION

In this Paper, we have investigated the dimensions of Linearly Polarized Edge Fed Rectangular patch antenna on

Rogers RT/Duroid 5870(tm) substrate for WLAN/Wi-Fi applications at a frequency of 2.4835 GHz. The various

performance properties are analyzed for the optimized design using Ansoft-HFSS. Also the Comparison has

been made among various Simulating softwares and their principle of operation in the table shown below.

7. FUTURE SCOPE

In Future, we can compare the results and performance by using Liquid Crystal Polymer, Ceramic substrate or

FR4 instead of Roger RT/Duroid 5870. Apart from that, we can use different feeding methods such as

Microstrip line feed, Probe feed techniques or Elliptical shaped patch can be used instead of Rectangular patch.

Table 1 : Principle of Operation of Various Software Packages used for Microstrip Patch Antennas

Software Name Principle of Operation FEKO Method of Moment HFSS Finite Element Method ADS Momentum Finite Difference Time Domain (FDTD) IE3D Method of Moment CST Microwave Studio Finite Integration Technique

8. REFERENCES [1] A. Vasylchenkot, Y. Schols, W. De Raedtt, G. A. E. Vandenbosch “A Benchmarking of Six Software

Packages for Full Wave Analysis of Microstrip Antennas”.

[2] C.A. Balanis, “Advanced Engineering Electro-magnetics”, John Wiley & sons, New York, 1989.

[3] Gagandeep Sharma, Deepak Sharma, Abhishek Katariya “An Approach to Design and Optimization of

WLAN Patch Antennas for Wi-Fi Applications”, IJECCT 2012,Vol.2(2).

[4] C.A. Balanis, “Antenna Theory”, 2nd Ed., John Wiley & sons, inc., New York.

[5] Atinder Pal Singh, “Various Methods and Software packages for Simulating Microstrip Patch Antennas”,

2nd National Conference on Emerging Trends in Engineering-April, 2012, Page =125-128.

[6] EMSS - EM Software & Systems Ltd, FEKO Suite 5.2 user manual, january 2006.

[7] James, J. R., P. S. Hall, “Handbook of Microstrip Antennas”, Peter Peregrinus, London, UK, 1989

[8] Pozar D. M., “Microstrip antennas," Proc. IEEE, Vol.80, No. 1, 79, 91, Jan. 1992

[9] Zeland Software, Inc., IE3D v. 11.2 user manual, january 2006, http:www.zeland.com.

[10] Narendra Neupane, Shankar Acharya, N.Anil Babu, B.T.P.Madhav, “Linearly Polarized Microstrip

Reatangular Patch Antenna On FR4 Substrate for High Speed WLAN Systems” GJCAT, Vol.1(2),2011.