You can refer the following papers. I hope you will find your answer in this following papers. If you have any further difficulty than reply the same.

1. Yves-Thierry Jean-Charles,Vichate Ungvichian and Juciana A. Barbosa, "Effects of Substrate Permittivity on Planar Inverted-F Antenna Performances," Journal of Computers, vol. 4, no. 7, pp. 610-614, July 2009

2. Jwo-Shiun Sun, Guan-Yu Chen, Cheng-Hung Lin, Kwong-Kau Tiong, and Y. D. Chen, "Application of Arti¯cial Dielectric Material for a PIFA Antenna", Progress In Electromagnetics Research Symposium, Hangzhou, China,pp. 725,726 March 24-28, 2008

3. D.M.Nashaat and H.Eisadek, "Miniturized E-Shaped Dual Band PIFA on FR4 Substrates," Radio Science Conference, 2006. NRSC 2006. Proceedings of the Twenty Third National , pp.1,6, 14-16 March 2006

doi: 10.1109/NRSC.2006.386317

4. Yves-Thierry Jean-Charles,Vichate Ungvichian and Juciana A. Barbosa, "A Study of substrate permittivity effects on the gain of planar inverted-F antennas," Southeastcon, 2008. IEEE , pp.296,299, 3-6 April 2008

doi: 10.1109/SECON.2008.4494307

Thank you Shobit.

I will definitely refer the papers.

The following paper may help you;

“Design of A Broadband Stacked Rectangular MPA with Shorting Pins for GSM-Family and Other Cellular Applications,” in Proceeding of the 8th International Conference in Modern Satellite, Cable and Broadcasting Services, TELSIKS 2007, Serbia, Nis, September 26-29, 2007, pp. 419-422. IEEE Catalogue Number: 07EX1875C, doi: 10.1109/TELSKS.2007.4376027.

1. The impedance of the PIFA can be controlled via the distance of the feed to the short pin . The closer the feed is to the shorting pin, the impedance will decrease; the impedance can be increased by moving it farther from the short edge. The PIFA can have it's impedance tuned with this parameter. You there if you don’t have impedance matching problem. :)

2. (up to you , try with FR4 cheapest one)

3. Possible, but why do you want that?

3. width of the pin is considered equal to that of the patch (maximum radiation efficiency)

short is just a pin (or assume W

1. The shorting pin should necessarily be kept at the edge of ground plane? Is there any change in the result if I keep the patch and shorting pin somewhere in the middle of the ground plane?

Ans: Answer to both these queries is NO. The placement is purely based on the design requirements.

If you are interested on effects of ground, then refer to the following paper:

M. -C. Huynh, W. Stutzman "Ground plane effects on planar inverted-F antenna (PIFA) performance," IEE Proc. on MAP, v. 150, Issue 4, pp: 209 - 213, 2003.

2. Which different substrates can be used?

Ans: Any substrate can be used. However, again it depends on design requirements.

3. If I use any substrate other than air and not keep my shorting pin at the edge then how will I be able to fabricate it?

Ans: Use the concept of via. Drill holes through the substrate & fill it with conducting (soldering) materials or insert copper wires & solder both ends to patch & ground plane.

4. What should be the width of the shorting pin? In literature, I found that normally either the width of the pin is considered equal to that of the patch or zero. How is zero width possible practically?

Ans: Assume that L, W, & S are the patch length, patch width & shorting pin width respectively. If c is speed of light, f is operating frequency & er is dielectric constant of substrate, then

S= L+W-c/(4f sqrt(er))

If S

*I did a lot of PIFA parametric study design and simulation. the performance of the antenna (meanly S11 resonant frequency ) are influenced by the distance between feeding (or its projection) and the shorting pin , that mean also the distance between the pin end the patch edge. Also, the width of the pin influences the antenna performance.

*For you case, if you don't use a substrate , you can't have a miniaturized antenna. you know PIFA is designed in the spirit of realizing the miniaturization criteria.

* the most known and good bargain is the FR4 epoxy

*You can view these joint files to have a survey conclusions about antenna parameters influence and you should know that the parameter influence is not proportional

http://www.scirp.org/journal/PaperInformation.aspx?PaperID=16936