RESEARCH POSTER PRESENTATION DESIGN © 2012

www.PosterPresentations.com

Microstrip antennas have been one of the most innovative topics in

antenna theory and design in recent years. Compared with conventional

antennas microstrip antennas have more advantages and better prospects. A

microstrip patch antenna consists of a radiating patch on one side of a

dielectric substrate which has a ground plane on the other side. The patch

is generally made of conducting material such as copper or gold and can

take any possible shape. These antennas are lighter in weight, low volume,

low cost, low profile, smaller in dimension and ease of fabrication and

conformity. We starts with a brief overview of the microstrip antenna,

feeding techniques, and its simulations through CST MICROSTRIPES

software. In order to further increase the performance of microstrip patch

antenna we design a novel microstrip patch antenna at ISM band while

using High impedance surface (HIS) as ground plane in patch antenna.

Unlike normal conductors, this new surface does not support propagating

surface waves, and it reflects electromagnetic waves with no phase

reversal. The geometry consists of two layers, the bottom one is a

continuous copper layer and the upper layer is textured into patches or

protrusions and are connected to the bottom layer through conducting via.

This surface can be described using a lumped parameter circuit model,

which accurately predicts many of its electromagnetic properties.

Abstract

Problem statement

This antenna will be designed in the CST Microstripes which is a complete

software tool for the 3D electromagnetic analysis and design of devices

and structures required in the high frequency range

First we designed microstrip patch antenna without using HIS surface by

designing a ground, substrate and finally patch is put on the top of

substrate. We then applied feed line technique and discretized to get the

results.

Then we designed microstrip patch antenna at 5.8 GHz using HIS surface.

We designed Sievenpiper high impedance surface. HIS is designed by first

designing continuous bottom copper layer and then we design array of

hexagons structure and dielectric was sandwiched between hexagons array

and bottom copper layer. And hexagons are connected to the bottom

copper layer through conducting via made of copper. Now this acts as

ground and we put another dielectric on this HIS surface and finally patch

is put on the top of upper substrate. We then applied microstrip feed line

technique and finally on discretizing we got the simulation results.

High impedance surface is shown in the figure below.

FIGURE: High impedance surface

METHODOLOGY

In the graph below two designs are compared. One is microstrip patch

antenna without HIS and other is with HIS. It can be clearly seen that

antenna without HIS has return loss of -23dB while the one with high

impedance surface has return loss of -45 dB. Similarly the BW of HIS

antenna is also greater than the one without HIS as shown in the graph

below.

Results Future work

• To decrease the size of microstrip patch antenna using High Impedance

surface.

• To increase efficiency and bandwidth of microstrip patch antenna while

changing gaps between HIS surfaces.

References

1) A. Scherer, et al., IEEE Trans. on Microwave Theory Tech., Special

Issues on Electromagnetic Crystal Structures, Designs, Synthesis, and

Applications, vol .47, Nov.1999.

(2) Balanis, C.A., Antenna Theory: Analysis and Design, John Wiley &

Sons, Inc, 1997.

(3) Ke Xiao, L.-W. L.-L.-J. (2011). A Novel Monopole-Alike Surface

Wave Antennas Designed Based on

Periodic Structures. Antenna Technology (iWAT), 2011 International

Workshop (pp. 3 - 7). Hong Kong:

Institute of Electrical and Electronics Engineers (IEEE).

(4) Dan Sievenpiper, Lijun Zhang, Ramulo F. Jimenez Broas, Nicholas G.

Alexopolous, Eli Yablonovitch,

Nov.1999, “High Impedance Electromagnetic Surfaces with a Forbidden

Frequency Band”, IE Transactions

on Microwave Theory and Technique, Vol.47, No.11.

Acknowledgement & contacts

All praise to AL-Mighty ALLAH, the most beneficent and merciful, who

enabled us to explore the present studies and also the Holy Prophet

MUHAMMAD (وسلمعليههللاصلى ) the source of knowledge and torch

of guidance for the entire world.

We are highly indebted to Dr M.Irfan khattak and Engr.Fawad Ahmad

and for their constant direction and encouragement in all phases of our

project. They devoted numerous hours from their busy schedule for our

help. It is only due to their endless help and support that we have been able

to complete the project.

1. Fazal Akbar

Email: fazalakbar923@gmail.com

2. Shah Hussain

Email: 11BNELE0426@uetpeshawar.edu.pk

Ordinary ground plane suffers with surface waves that degrade the

performance of the antenna. Surface waves where it can be obtained

from the leaky waves in the smooth ground plane can lead to poor

performance and lower efficiency of an antenna. It is because surface

waves are the reverse radiation of the current that travel along the

interface between the free-space and top copper layer of ground plane.

These kind of unwanted waves are excited at the edges and corners of

the ground plane. When the wanted waves are added with surface waves,

multipath interference and back lobes radiation will be formed. Surface

waves can always occur if the ground plane used is smooth and flat. It is

because such characteristics that can be obtained from perfect electric

conductor plate, allow surface currents to flow to infinite distance. This

will also lead to the multipath interference.

UET Peshawar Bannu Campus

Fazal Akbar 11BNELE0428 Shah Hussain 1 1BNELE0426 Advised By: Dr M.Irfan KhattakSupervised by: Engineer Fawad Ahmed

Novel High Impedance Surface Based Antenna Design At 5.8 GHz

Aims and objectives

The main objective of the project is to design high impedance surface

based antenna for wireless Lan at 5.28 Ghz. This antenna will be more

efficient as compared to the other existing antennas regarding the

problem created due to surface waves.

Conclusions

As we know that HIS has two important properties i.e. they suppress

surface waves and they have property of in phase reflection due to which

its performance is increased. So in the figure we have shown microstrip

antenna without HIS and then in fig: 11 we have combined the simulation

results of both HIS and ordinary antenna. From FIG: 11 we can clearly see

that due to HIS the performance of antenna is increased i.e. the bandwidth

is increased and return loss has decreased.