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World Journal of Science and Technology 2012, 2(4):104-107ISSN: 2231 2587Available Online: www.worldjournalofscience.com

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Proceedings of"Conference on Advances in Communication and Computing (NCACC'12)Held at R.C.Patel Institute of Technology, Shirpur, Dist. Dhule,Maharastra,India.

April 21, 2012

Teaching tools for microstrip patch antenna design

Alkeshkumar M Khatri and Jagadish B Jadhav

Department of Electronics & Telecommunication,R C Patel Institute of Technology,Shirpurr,Dhule,M.S., India

AbstractThis paper provides details on how to investigate a new method of teaching microstrip patch antenna design forundergraduate students by using MATLAB. This is achieved by designing a friendly graphical user interface (GUI) formicrostrip patch antennas through which antenna parameters and radiation pattern can be determined. Effect of changes inbasic parameter microstrip Patch Antenna on its Radiation Patter and other parameters can be determined by using GUI.Understanding the behavior of the Microstrip Patch Antenna and Design of it for different material with the use of theGraphical User Interface using MATLAB is better way of Analysis.

Keywords: Ractangular & Circular Microstrip Patch Antenna, Graphical User Interface, Matlab.

INTRODUCTION

Studying antennas and wave propagation phenomena usinginteractive graphics and animations becomes nowadays afundamental tool for describing and understanding electromagneticconcepts. This aspect is strongly related with wave propagation,where the propagation properties of the waves or how to plot theradiation patterns of antennas are not so easy to understand forundergraduate students, due to simple, static, oral explanations.

Currently, several products in which computer tools are used havebeen developed such as Ansoft Ensemble, IE3D, MWO (MicrowaveOffice), SONNET, ADS (Agilent Advance Design System), COMSOL,MATLAB ,HFSS (High Frequency Structure Simulation) etc formodeling and simulation of complicated microwave and RF printedcircuit, antennas, and other electronics component. Many of thesesoftwares are commercially available at a very high cost or in theleast, are proprietary.

MATLAB has become a ubiquitous math, data manipulation,signal processing, and graphics software package [1]. Engineers useits powerful functions for analysis and design in many areasincluding antenna design. MATLAB is general-purpose software, somany arcane applications, like antenna design, are done usingspecial purpose commercial software. Although these packages canmodel very complex electromagnetic systems, they lack some of thepowerful analysis tools in MATLAB. Using MATLAB to control thesecommercial electromagnetic solvers creates a powerful tool for

design, analysis, and control. This paper provide the means of usingMatlab to provide a suitable application that calculates the mainparameters of microstrip patch antenna, plots the radiation patternsand also determine the antenna performance characteristics throughelectromagnetic simulation. This is achieved via a GUI generated bythe Matlab that allow the user to modify, visualize and compare thewhole process of the design whenever there is a need to fabricatethe antenna.

Patch antennas play a very significant role in todays world ofwireless communication systems. A Microstrip patch antenna is verysimple in the construction using a conventional Microstrip fabricationtechnique. The most commonly used Microstrip patch antennasare rectangular and circular patch antennas (Fig 1). These patchantennas are used as simple and for the widest and mostdemanding applications. Dual characteristics, circular polarizations,dual frequency operation, frequency agility, broad band width, feedline flexibility, beam scanning can be easily obtained from thesepatch antennas .here we are doing the design of a microstrip patchantenna and we have to compare the differences betweenrectangular and circular patch antenna using matlab simulationsoftware.

Fig 1. Basic Microstrip patch antenna

*Corresponding Author

Alkeshkumar M KhatriDepartment of Electronics & Telecommunication,R C Patel Institute ofTechnology,Shirpurr,Dhule,M.S., India

Email: alkesh.eng@gmail.com

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World Journal of Science and Technology 2012, 2(4):104-107 105

MICROSTRIP PATCH ANTENNA

In its most basic form, a Microstrip patch antenna consists ofa radiating patch on one side of a dielectric substrate which has aground plane on the other side as shown in Fig 2. The patch isgenerally made of conducting material such as copper or gold andcan take any possible shape. The radiating patch and the feed lines

are usually photo etched on the dielectric substrate.

Fig 2. Structure of a Microstrip Patch Antenna Microstrip patch Antenna

In order to simplify analysis and performance prediction, thepatch is generally square, rectangular, circular, triangular, elliptical orsome other common shape as shown in Fig 3

Fig 3. Common shapes of microstrip patch elements

Merits of Microstrip Patch Antenna

Some of their principal merits of Microstrip Patch Antennadiscussed by [8] and Kumar are given below:

Light weight and low volume.

Low profile planar configuration which can be easily madeconformal to host surface.

Low fabrication cost, hence can be manufactured in largequantities.

Supports both, linear as well as circular polarization.

Can be easily integrated with microwave integrated circuits(MICs).

Capable of dual and triple frequency operations.

Mechanically robust when mounted on rigid surfaces.

Demerits of Microstrip Patch Antenna

Microstrip patch antennas suffer from a number ofdisadvantages as compared to conventional antennas. Some of theirmajor disadvantages discussed by [9] and Garg et al [10] are givenbelow:

Narrow bandwidth

Low efficiency

Low Gain

Extraneous radiation from feeds and junctions

Poor end fire radiator except tapered slot antennas

Low power handling capacity.

Surface wave excitation

Feed Techniques of Microstrip Antennas

Microstrip patch antennas can be fed by a variety of methods.These methods can be classified into two categories- contacting andnon-contacting. In the contacting method, the RF power is feddirectly to the radiating patch using a connecting element such as amicrostrip line. In the non-contacting scheme, electromagnetic fieldcoupling is done to transfer power between the microstrip line andthe radiating patch [5]. The Comparision of four most popular feed

techniques used are the microstrip line, coaxial probe (bothcontacting schemes), aperture coupling and proximity coupling (bothnon-contacting schemes) .

Table 1. Comparing the different feed techniques [4]

CharactericsMicrostripLine Feed

Coaxial FeedAperturecoupled

Feed

Proximitycoupled

Feed

Spurious feedradiation

More More Less Minimum

Reliability BetterPor due toSoldering

Good Good

Ease of Fabrication EasySoldering

and Drilling

Needed

Alignment

Required

Alignment

RequiredImpedanceMatching

Easy Easy Easy Easy

DESIGN ANALYSIS OF MICROSTRIP PATCH ANTENNA

Microstrip patch antenna analysis can be done using threepopular models: the transmission line model, cavity model and fullwave model (Method of Moments- includes integral equationssolution) [3]. The first model is the simplest of all and the lessaccurate [5]. The cavity model is more accurate, thus muchcomplex compared to the transmission line model, and gives a goodphysical insight [6]. Full wave model is the most accurate andcomplex of all models and can analyze from single elements, toinfinite antenna arrays, or arbitrary shaped elements. In this paperGUI is prepared in MATLAB using the transmission line model tocalculate the dimensions and the cavity model to plot the radiationpatterns for rectangular microstrip antenna. Alsosome perameters ofcircular microstrip patch antenna are analyzed using transmissionline model.

Rectengualar patch antenna

Basic Design Equations of Rectangular Microstrip PatchAntenna are as under.

Effective Dielectric Constant can be given by:

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Khatri and Jadhav106

where, reff = Effective dielectric Constant

r = Dielectric Costant of the Substrateh = Height of the Dielectric SubstrateW = Width of the Patch

Fig 4. Top view and side view of Rectangular Microstrip Patch Antenna

In the Fig. 4a shown above, the Microstrip patch antenna isrepresented by two slots, which are separated by the transmissionline has said previously with a length L and it is open circuited on thetwo ends. The width of the structure has a maximum voltage andminimum current as it is an open ended circuit. The tangential andthe normal components of the fields at the edges are resolved withrespect to the ground plane.

It is seen from fig. 4b that the normal components of theelectric field at the two edges along the width are in oppositedirections and thus out of phase since the patch is /2 long andhence they cancel each other in the broadside direction. Thetangential components (seen in Fig. 4b), which are in phase, means

that the resulting fields combine to give maximum radiated fieldnormal to the surface of the structure. Hence, the edges along thewidth can be represented as two radiating slots, which are /2apart and excited in phase and radiating in the half space above theground plane. The fringing fields along the width can be modeled asradiating slots and electrically the patch of the microstrip antennalooks greater than its physical dimensions. The dimensions of thepatch along its length have now been extended on each end by adistance L, which is given empirically by [7] as:

The actual length L of the patch is given as

The effective length of the patch Leff now becomes

For the given resonent frequency fo, the ellfective length is given as

For the effective radiation width of the patch W is given as

To determine the field radiated by each slot, the total field isthe sum of the two-element array with each element representingone of the slots.

E-Plane ( =90o , 0o 90o and 270o 360o)

H- plane ( = 0o, 0o 90o )

The gain of the antenna is the quantity which describes theperformance of the antenna or the capability to concentrate energythrough a direction to give better picture of the radiationperformance.it is given as

G = x D

Where, = efficiency of the antenna,D = Directivity

ANTENNA DESIGN

In this paper utilization of the design equation of rectangularpatch antenna is done for the preparation of the Graphical UserInterface in MATLAB.GUI for the Rectangular patch antenna is asshown below.

In GUI resonant frequency (Fr), Input Impedance, DielectricThickness, Dielectric Constant are taken as a input perameter.

As shown in fig 5, antenna perametes are calculated using

this GUI as well as the radiation pattern for given input is plotted onGUI.

As mention in title of paper this GUI includes the Help optionfor the user, by which user can get the basic information related tothe Microstrip Antenna like, What is Antenna?, What is MicrostripPatch Antenna?, What is Advantages of Microstrip Patch Antenna?,What is Disadvantages of Microstrip patch Antenna? etcwithrelated diagram.

RESULTS

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Fig 5. GUI front end for rectangular patch antenna(input fr = 30 MHz, Dielectric Thickness 2mm,Dielectric Constant 11.8 for silicon)

DISCUSSION WITH FUTURE SCOPE

From the Equation of the Rectangular manual calculation ofall parameter is complex. By the use of the GUI this can be easy tocalculate it. The Effect of the Changes in input parameter onradiation pattern can be easily analyzed by the use of GUI. Asmentioned in results by changes in the material of the patch physicalparameter of the Microstrip Patch is changes, this will be helpdesigner to determine the antenna performance and makenecessary adjustment before fabrication.

CONCLUSION

This work was aimed at designing a effective GUI forRectangular Microstrip Patch Antenna. Alongside this, variousparameters viz actual and effective length, width, radiation power,directivity, VSWR, which dictate the ultimate performance of theantenna were determined by simulation using a GUI developed inMATLAB. Deduction were made on results obtained for differentsubstrate and it was discovered that GaAs is suitable for smallerantenna size.

REFERENCES

[1] R .L. Haupt, 2008. Using MATLAB to conteol CommercialComputational Electromagnetics Software AcesJournal,Vol 23,1.

[2] D.M.Pozar,D.H.Schaubert 1995.Microstrip Antenna,theAnalysis and design of Microstrip Antennas and ArraysIEEE press, New York,USA.

[3] C.A.Balanis 1982 Antenaa Theory: Analysis and DesignJohn Wiley & Sons. 819-873.

[4] K.O.Odeyemi,D.O. Akande and E.. O. Ogunti 2011 Matlab

Based Teaching Tools for Microstrip Patch Antennadesign,JOT-Vollume 7.

[5] E.H. Van Lin, A.R.Van de Capelle 1984 Transmission LineModel for Mutual Coupling between Microstrip AntennasIEEE Trans. Antennas Propagation Vol. AP-32-8,pp.816-821.

[6] Dr. T K Bandoupadhya, Dr Anubhuti khare, Rajesh Nema,Puran Gour 2010. New Multiband Microstrip PatchAntenna On Rt Duroid 5870 Substrate for PervasiveWireless Communication (X & Ku Band),IJETSE,Volume 2,No. 2.

[7] G.Sing 2010. Design Consideration for rectangularmicrostrip patch antenna on electromagnetic crystalsubstrate at terahertz frequency Infrared Physics &Technology Volume 53, Issue 1,pp. 17-22.

[8] T.Durga Prasad, K.V.SatyaKumar, MD Khwaja Muinuddin,Chisti B.Kanthamma,V.Santoshkumar 2011.Comparisonof Circular and Rectangular Microstrip Patch AntennasIJCA,Vol 02,Issue 04.

[9] Alka Verma,Neelam Srivastava 2011 Analysis and Designof Rectangular Microstrip Antenna in X-band MIT IJECE,Vol-01.

[10]Murli Manohar, S K Behera, P K Sahu 2009 Design ofSingle Feed Dual Polarized and Dual FrequencyRectangular Patch Antenna ,5th ICMAPRS-Jodhpur.

[11]L. M. Si, X. Lv 2008. CPW-FED Multi Band OmniDirectional Planar Microstrip Antenna using CompositeMetamaterial Resonators for Wireless CommunicationProgress in Electromegnetic Research, PIER 83, pp.133-146.

[12]S. Maci, G. Biffi Gentili, G. Avitabile 1993 Single-LayerDual- Frequency Patch Antenna Electronics Letters 29.

[13]Y.j.Wang, W.J.Koh, J.H.Tan, P.T.Teo, P.C.Yeo 2001. ACompact and BroadbandMicrostrip Patch Antenna,IEEE.

[14]Xin Mi Yang, Quan Hui Sun, Ya Jing, Qiang Cheng, XiaoYang Zhou, Hong Wei Kong, and Tie Jun Cui 2011.Increasing the Bandwidth ofMicrostrip PatchAntenna byLoading Compact Arti?cial Magneto-Dielectrics IEEETransactions on Antennas and Propagation, vol. 59, no.2.

[15]Matthew J. Inman,Atef Z. Elshebeni 2008. MATLABGraphical Interface for GPU Based FDTD Method 2008Asia-Paci?Sympsoium on Electromagnetic Compatibility,Singapore.

[16]Indrasen Singh, Dr. V.S.Tripathi 2011. Microstrip Patch

Antenna and its Applications : Survey IJCTA pp.1595-1599.