Presentation for design of wide bandwidth micro strip patch using circular polarisation

PRESENTED BY :-
Abhinav Singh(EC-A)
Ashutosh Pandey (EC-A)
Ankit Kashyap(EC-A)
Under the kind guidance of
Dr. Dhirendra Kumar

Introduction
In its most basic form, 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
Structure of a Microstrip Patch Antenna
For good antenna performance, a thick dielectric substrate having a low dielectric
constant is desirable since this provides better efficiency, larger bandwidth and better
radiation .
 In general Micro strip antennas are also
known as
“ PRINTED ANTENNAS ”.
 These are mostly used at microwave
frequencies.
 Because the size of the antenna is directly
tied the wavelength at the resonant
frequency.
 Micro strip patch antenna or patch antenna
is a narrowband wide-beam antenna.

 Micro strip antennas are easy to fabricate and comfortable on
curved surface .
 The directivity is fairly insensitive to the substrate thickness.
 Micro strip patch antennas patches are in variety of shapes ,
such as rectangular , square , triangular and circulator …etc.
 The patch usually fed along the centerline to symmetry and thus
minimize excitation of undesirable modes.

Substrates are:
The most commonly used substrates are,
1) Honey comb(dielectric constant=1.07)
2)Duroid(dielectric constant=2.32)
3)Quartz(dielectric constant=3.8)
4)Alumina(dielectric constant=10)
5) FR4 (dielectric constant=4.5)
 A thicker substrate will increase the radiation
power , reduce conductor loss and improve Band
width.

L = Length of the Micro-
strip Patch Element
W = Width of the Micro-
strip Patch Element
t= Thickness of Patch
h = Height of the Dielectric
Substrate.

• Dielectric constant(εr)=
2.2 ≤ εr≤ 12.
•Frequency (fr) = 2.4 Ghz
•Height (h) = 1.59 mm
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

c= 3 x 10^8 m/sec
εr =4.5 (FR4)
fo= 2.4 GHz
Therefore,
W=40.3 mm

εr =4.5(FR4)
h = 1.59 mm
W= 40.3mm
Therefore ,
is equal to 3.5533

εr =4.5(FR4)
h=1.59 mm
W = 40.3mm
Therefore ,
The value of is 7.503x10-1 mm

fo
= 2.4 GHz
= 3.5533
c= 3x108 m/sec
therefore , the value of is 33.156 mm & value of L will be
31.6554 mm.

Advantages:
 Low fabrication cost, hence can be manufactured in
large quantities.
 Easily integrated with microwave integrated circuits
(MICs).
 Capable of dual and triple frequency operations.
 Supports both, linear as well as circular polarization.
 Low cost , Less size , Low Mass .
 Mechanically robust when mounted on rigid surfaces.
 High Performance
 Light weight and low volume.

Disadvantages:
 Narrow bandwidth associated with tolerence
problem
 Lower Gain(Nearly 6db) .
 Large ohmic losses in feed structure of arrays.
 Excitation of surface waves .
 Most microstrip antennas radiate into half-space .
 Relatively low efficiency (due to dielectric and
conductor losses) .
 relatively high level of cross polarization radiation
Spurious feed radiation (surface waves, strips, etc.)
 Inherently low impedance bandwidth.
Low efficiency .
Extraneous radiation from feeds and junctions .

Applications:
Used in mobile satellite communication
system.
Direct broad cast telivision(DBS).
Wire less LAN’S.
Feed elements in coaxial system
GPS system.
Missiles and telementry
UHF Patch Antennas for Space

Presentation for design of wide bandwidth micro strip patch using circular polarisation

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Presentation for design of wide bandwidth micro strip patch using circular polarisation