Presentation for design of wide bandwidth micro strip patch using circular polarisation
1. PRESENTED BY :-
Abhinav Singh(EC-A)
Ashutosh Pandey (EC-A)
Ankit Kashyap(EC-A)
Under the kind guidance of
Dr. Dhirendra Kumar
2. 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.
3. 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.
4.
5. 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.
6. 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.
7. • 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
8. c= 3 x 10^8 m/sec
εr =4.5 (FR4)
fo= 2.4 GHz
Therefore,
W=40.3 mm
9. εr =4.5(FR4)
h = 1.59 mm
W= 40.3mm
Therefore ,
is equal to 3.5533
11. 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.
12. 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.
13. 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 .
14. 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