Study & Design of Micro-strip Patch

AntennaPRESENTED BY :-

Diptajit Biswas(EC/08/50)

Amit Samanta (EC/08/49)

Saikat Mandal(EC/08/66)

Under the kind guidance of ,

Mr. Asim Biswas

Introduction

O Need of Antenna

O Progress of

Communication

system

AIM & OBJECTIVES

O To study Micro-strip Patch Antenna.

O To design and implement this antenna using the software HFSS, v 11.0 .

How does an antenna work ?

•Antenna is one type of transducer that converts the electrical energy into the electro-magnetic energy in form of electromagnetic waves.

•Antennas are required by any radio receiver or transmitter to couple its electrical connection to the electromagnetic field.

Antenna characteristics :-

•Power gain•Directivity•Antenna radiation patterns•Polarization

Overview of micro-strip Antenna

O Developed after revolution in Electronic Circuit Miniaturization & LSI in 1970.

O Used on rockets & missiles previously.

O Designer’s choice.

Micro-strip Patch Antenna

What is Micro-strip Antenna ?

A Micro-strip patch antenna consists of a radiating patch on one side of a dielectric substrate which has a ground plane on the other side.

Invented by Bob Munson in 1972 (but earlier work by Dechamps goes back to1953).

Different Parameters of Micro-strip Antenna

OL = Length of the Micro-strip Patch Element

OW = Width of the Micro-strip Patch Element

Ot= Thickness of Patch

Oh = Height of the Dielectric Substrate.

Basic Principles of Operation

•The patch acts approximately as a resonant cavity (short circuit walls on top and bottom, open-circuit walls on the sides).•In a cavity, only certain modes are allowed to exist, at different resonant frequencies.• If the antenna is excited at a resonant frequency, a strong field is set up inside the cavity, and a strong current on the (bottom) surface of the patch. This produces significant radiation (a good antenna).

Different Shapes of Micro-strip Patch Elements

Advantages of Micro-strip Patch Antenna

•Light weight and low volume.• Low profile planar configuration which can be easily made conformal to host surface.• Low fabrication cost, hence can be manufactured in large quantities.• 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.

Disadvantages:-

•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:-Micro-strip antenna can be feed by variety of methods. This methods can be classified into two categories-contacting and non-contacting. The foremost popular feed techniques used are :-

O Micro-strip line.O Co-axial probeO Aperture couplingO Proximity

coupling

Software used to design Micro-strip Patch Antenna

OHFSS is commercial finite elementOmethod solver for electromagnetic OStructures.from Anasys Corp. OHFSS stands for High Frequency OStructural Simulator. It is one of theOSeveral commercial tools used for Oantenna design . It was developedOby Prof. Zontal Cendes and his Ostudents at Carnegie Mellon Univ.Oin the year 1989.

The Design Specifications:-

• Dielectric constant(εr)= 2.2 ≤ εr≤ 12.•Frequency (fr) = 1.85 to 1.90 GHz•Height (h) = 0.003 λo≤h≤0.05 λo• Velocity of light (c) = 3×10^8 ms-1 .•Practical width (W) = W< λo , , where λo is the free-space wavelength•Practical Length (L) = 0.3333λo< L < 0.5 λo

Calculation of Parameters:-

c= 3.8 x 10^8 m/secεr =11.9fo= 1.85 GHzTherefore,W=31.9 mm

εr =11.9h = 1.59 mmW= 31.9 mmTherefore , is euqal to 10.7611

εr =11.9h=1.59 mmW = 31.9 mmTherefore , The value of is 6.72x10-1 mm

fo= 1.85 GHz

= 10.7611

c= 3x108 m/sectherefore , the value of is 24.7 mm & value of L will be 23.36 mm.

PATCH ANTENNA COVERED BY AIRBOX

WAVE PORT

DETERMINATION OF CENTER FREQUENCY USING S-

PARAMETER:-

VSWR PLOT OF MICROSTRIP

ANTENNA

PERFECT E ASSIGNED TO SUBSTRATE

PERFECT E ASSIGNED TO PATCH

APPLICATIONS• The use of micro-strip

antennas for integrated phased array systems.

• Used in GPS (Sat. Navigational System) technology.

• Mobile satellite communications, the Direct Broadcast Satellite (DBS) system & remote sensing.

• Non-satellite based applications- such as medical hyperthermia.

CONCLUSIONOThe design of patch antenna using ANSOFT HFSS Software has been shown here. Our project on Design of Microstrip Antenna which is based on Microstrip Feed Line Technique.OMany more design options and impletation techniques are available.

REFERENCES:-• http://en.wikipedia.org/wiki/Microstrip_antenn

a• http://www.microwaves101.com/encyclopedia

/antenna_ustrip.cfm• C. A. Balanis, “ Antenna Theory, Analysis and

Design”, JOHN WILEY & SONS,INC, New York 1997.