Study & Design of Micro-strip Patch Antenna using circular polarisation

Study & Design of Wide bandwidth Micro-strip Patch Antenna with Circular PolarisationPRESENTED BY :-

Abhinav Singh(EC-A)Ashutosh Pandey (EC-A)Ankit Kashyap(EC-A)

Under the kind guidance of Dr. Dhirendra Kumar

IntroductionIn 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 sideStructure 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.

Designing of patch:

Different parametersSubstrateconnectors

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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.

Different Parameters of Micro-strip AntennaL = 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.

The Design Specifications:-

Dielectric constant(r)= 2.2 r 12.Frequency (fr) = 2.4 GhzHeight (h) = 1.59 mm oh0.05 o Velocity of light (c) = 310^8 ms-1 .Practical width (W) = W< o , , where o is the free-space wavelengthPractical Length (L) = 0.3333o< L < 0.5 o

Calculation of Parameters:-

c= 3 x 10^8 m/secr =4.5 (FR4)fo= 2.4 GHzTherefore,W=40.3 mm

r =4.5(FR4)h = 1.59 mmW= 40.3mmTherefore , is equal to 3.5533

r =4.5(FR4)h=1.59 mmW = 40.3mmTherefore , The value of is 7.503x10-1 mm

fo= 2.4 GHz = 3.5533

c= 3x108 m/sectherefore , 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 PerformanceLight weight and low volume.

Disadvantages:Narrow bandwidth associated with tolerence problemLower 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 .Low power handling capacity.

Applications:Used in mobile satellite communication system.Direct broad cast telivision(DBS).Wire less LANS.Feed elements in coaxial system GPS system.Missiles and telementryUHF Patch Antennas for Space

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