o l . 6, issu e 1, jan - mar c h 2015 issn : 2230-7109

IJECT Vol. 6, IssuE 1, Jan - MarCh 2015 ISSN : 2230-7109 (Online) | ISSN : 2230-9543 (Print)

w w w . i j e c t . o r g 56 InternatIonal Journal of electronIcs & communIcatIon technology

Studies onChange in Position of Radiating Plane and Position of Feed Point on Antenna Characteristics

1Sreyosee Mukherjee, 2Prasanna Kumar Biswas, 3Manojit Roy, 4Prof. Partha Pratim Sarkar1,2,3,4DETS, University of Kalyani, Kalyani, Nadia, India

AbstractIn this article, the effect of different positions of radiating plane with respect to ground plane as well as effects of position of feed point on antenna characteristics arestudied. The feed position is gradually changed and the readings are noted and then for the optimum feed point the position of the radiating patch are changed and the readings are noted. They are studied to find a relation between them and also to find the optimum value. The simulations are done by MOM based Ansoft (Designer) software.

KeywordsMicrostrip Antenna, Broadband, Resonating Frequency, Method of Moment

I. IntroductionRecently, in the field of wireless local area network, therole of Microstrip Antennas (MSAs) acquires tremendous importance [1]. A microstrip antenna consists of a patch metallization on agrounded substrate [2]. For good antenna performance, a thick dielectric substrate having a low dielectric constant is desirable since this provides larger bandwidth and better radiation.While the trendtowards miniaturization of electronic circuitrycontinues, antennas remain the bulkiest part of wireless devices [3]. So microstrip antennas are widely used in a broad range of militaryand commercial applications mainly because of their advantageousfeatures in terms of low profile, low cost, lightweight, and easymanufacturability [4]. However, theyalso have some drawbacks, ranging from narrow bandwidth to lowgain[5].Usually the gain of this antenna is low. So our primary aim is to overcome the disadvantages and achieve a high gain and broadband antenna with low resonant frequency for achieving compactness.

II. Design of AntennaThe structure of the proposed microstrip patch antenna with single feed designed FR4 Epoxy substrate of dielectric constant 2.4, thickness 1.6mm and loss tangent 0.0016 is depicted in Fig. 1

Fig. 1: Initial Reference Design

The patch is initially placed at the centre of the ground plane and the position of the feed points are gradually changed and the results are noted.The further work is done based on the best value of feed pointposition obtained from the readings.

Fig. 2: Shifting of Feed Point

Next keeping the feed at its optimum position,the radiating patchis gradually shifted 1mm at a time along both x or y axis and the readings obtained are noted in a tabular fashion.

Fig. 3: Shifting of Patch Keeping Feed Point Constant

Then the optimum result is used to design a high gain and broadband microstrip antenna.

III. ResultThe desired results are obtained for only 2 positions of y-axis while the x-axis is changed gradually and the results of the 2 positions are almost equal due to symmetry.

IJECT Vol. 6, IssuE 1, Jan - MarCh 2015

w w w . i j e c t . o r g InternatIonal Journal of electronIcs & communIcatIon technology 57

ISSN : 2230-7109 (Online) | ISSN : 2230-9543 (Print)

Fig. 4: Result of Shifting Feed Point

From the readings obtained the change in the percentage bandwidth and gain with the change in feed point positions when y-axis is constant is plotted as shown in fig. 4 and fig. 5.

Fig. 5: Variation of Percentage Bandwidth With Variation of Feed Point Position

Fig. 6: Variation of Gain With Variation of Feed Point Position

Next keeping the ground plane constant and the feed point at its optimum position, the readings for change in patch positions are noted.The change in percentage bandwidth and gain with change in radiating patch positions along x-axis for different values of y-axis is plotted and is shown in fig. 6 and fig. 7.

Fig. 7: Variation of Percentage Bandwidth in x-axis When y-axis is Constant

Fig. 8: Variation of Gain in x-axis when y-axis is Constant

One of the optimum designs obtained from the study has been used for further designing of antenna as shown in fig. 8.

Fig. 8: Optimum Design Used From the Study

The plots for percentage bandwidth and gain for the above design are given in fig. 9 and fig. 10.



Fig.9: Reflection Coefficient Characteristics for the Optimum Design Used

Fig. 10: Swept Gain Characteristics for the Optimum Design Used

For this design there are 2 resonating frequencies the first one at 8.78 GHz, and the second one at 9.33 GHz,the percentage bandwidth is 18.75% and gain is 5.85 dBi.

IV. Enhancement of Gain and Bandwidth Based on the Optimal DesignA parasitic element has been added to the design to see the effect.

Fig. 11: 1st Modification of the Optimum Design

The gain and bandwidth curves obtained are shown in fig. 12 and 13.

Fig. 12: Reflection Coefficient Characteristics for the 1st Modified Design

Fig. 13: Swept Gain Characteristics for the 1st Modified Design

Here the resonating frequency is 8.85 GHz, the percentage bandwidth is 10.16% and gain is 6.82 dBi. Next a slot has been introduced in the design to enhance the gain and bandwidth.

Fig. 14: 2nd Modification of the Optimum Design

The corresponding gain and bandwidth curves are as follows.




Fig.15: Reflection Coefficient Characteristics for the 2nd Modified Design

Fig.16: Swept Gain Characteristics for the 2nd Modified Design

Here a very wide band with three resonating frequencies are obtained, the first one at 8.33 GHz,the second one at 9.09 GHz, and the third one at 10.43 GHz,the percentage bandwidth is 28.54% and gain is 5.53 dBi. Next the ground plane of the optimal design has been modified.The modification with dimensions is shown in fig 17.

Fig. 17: 3rd Modification of the Optimum Design

The graphs for the bandwidth and gain are given in fig. 18 and 19 respectively.

Fig. 18: Reflection Coefficient Characteristics for the 3rd Modified Design

Fig. 19: Swept Gain Characteristics for the 3rd Modified Design

Here the resonating frequency is 8.74 GHz, the percentage bandwidth is 27.34% and gain is 6.93 dBi. The above design has been further modified with the addition of a parasitic element to enhance the bandwidth.

Fig. 20: 4th Modification of the Optimum Design

The bandwidth gets enhanced for this design even though the gain remains same.



Fig. 21: Reflection Coefficient Characteristics for the 4th Modified Design

Fig. 22: Swept Gain Characteristics for the 4th Modified Design

Here the resonating frequency is 8.75 GHz, the percentage bandwidth is 29.02% and gain is 6.93 dBi. The radiation patterns at the resonating frequency,i.e. 8.75 GHz, are shown below seperately for phi=0 Deg and phi=90 Deg,

Fig. 23: Radiation Pattern for phi=0 Deg for the 4th Modified Design

Fig. 24: Radiation Pattern for phi=90 Deg for the 4th Modified Design

V. ConclusionBy systematically finding out the optimal feed point position and radiating patch position, with very simple change in design, enhancement of the gain and bandwidth of the antenna can be obtained.With the final design a very high gain broadband antenna with gain of 6.93 dBi and percentage bandwidth of 29.02% has been obtained.The work can also be done with rectangular and circular shapes of ground plane and radiating plane in the future.

Reference[1] Srija De, Sushanta Sarkar, Sushanta Biswas, Debasree

Sarkar, Partha Pratim Sarkar , “Investigation on Broadband Microstrip Two Element Monopole Antenna with High Gain”, IETE JOURNAL OF RESEARCH | VOL 59 | ISSUE 4 | JUL-AUG 2013

[2] K. Mandal, S. Sarkar, P. P. Sarkar,“Bandwidth Enhancement of Microstrip Antennas by staggering effect”, MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 53, No. 10, October 2011, pp. 2446-2447

[3] Shatarupa Neogi, Anup K. Bhattacharjee, Partha Pratim Sarkar, “Size reduction of rectangular Microstrip Antenna”, MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 56, No. 1, January 2014, pp. 244-248

[4] Kaushik Mandal, Partha Pratim Sarkar,“A compact high gain microstrip antenna for wireless applications”,International Journal of Electronics and Communications (AEÜ)(June 2013)

[5] Kaushik Mandal, Partha Prtim Sarkar,“High Gain Wide-band U-shaped Patch Antennas with Modified ground planes”, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 61, NO. 4, APRIL 2013,2279-2282

[6] C.A. BALANIS, ANTENNA THEORY:ANALYSIS & DESIGN, 2ND EDITION, WILEY, HOBOKEN, NJ2008

[7] Girish Kumar, K. P. Ray,"Broadband Microstrip Antennas", ARTECH HOUSE, INC., 2003.




Sreyosee Mukherjee obtained her B.Tech from Asansol Engineering College, Asansol, Burdwan in the year of 2012. She is currently pursuing M.Tech in Communication Engineering in Dept. of Engineering and Technological Studies, University of Kalyani, Kalyani, India.

Prasanna Kumar Biswas obtained his B.Tech from Abacus Institute of Engineering & Management, Mogra, Hooghly in the year of 2013. He is currently pursuing M.Tech in Communication Engineering in Dept. of Engineering and Technological Studies, University of Kalyani, Kalyani, India.

Manojit Roy obtained his B.Tech from Calcutta Institute of Engineering and Management, Tollygunge, Kolkata in the year of 2013. He is currently pursuing M.Tech in Communication Engineering in Dept. of Engineering and Technological Studies, University of Kalyani, Kalyani, India.

Partha Pratim Sarkar obtained his Ph.D in Engineeringfrom Jadavpur University in the year 2002. He hasobtained his M.E. from Jadavpur University in the year1994. He earned his B.E. degree in Electronics andTelecommunication Engineering from BengalEngineering College (Presently known as BengalEngineering and Science University, Shibpur) in

the year1991. He is presently working as a Senior Scientific Officer (Professor Rank)at the Dept. of Engineering and Technological Studies, University of Kalyani.His area of research includes Microstrip Antenna, microstrip Filter, FrequencySelective Surfaces, and Artificial Neural Network. He has contributed tonumerous (more than 80 publications) research articles in various journalsand conferences of repute. He is a life fellow of IETE, and fellow of IE (India).

o l . 6, issu e 1, jan - mar c h 2015 issn : 2230-7109

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