By - ARIJIT SARKAR

ANTENNA

2INTRODUCTION

An antenna is a specialized transducer that converts Alternating Current (AC) into Radio-Frequency (RF) fields or vice-versa.

3WORKING OF AN ANTENNAWAVE

RADIATION An antenna radiates waves by

changing the flow of current inside a conducting wire.

By time varying, if the flow of current is uniform, the straight wire will not radiate.

Transmission line connects the antenna with the voltage source.

If we bend the wire, even with uniform velocity, the curve along the wire will create an acceleration in the current flow & the wire will radiate.

4ANTENNA PARAMETERS

Efficiency :- =

Gain :- G = Directivity Antenna Efficiency

It is the parameter which quantifies the radiation focusing capability of an antenna. It is one of the very important parameters used for comparing the performance of different antennas.

Directivity :-

Bandwidth :- BW

5TYPES OF ANTENNAS

Antenna

Dipole Antenna

Loop Antenna

Monopole Antenna

Array Antenna

Yagi Antenna Log-Periodic

Antenna Corner

Reflection Antenna

Whip Antenna Rubber Ducky

Antenna T – Antenna

Batwing Antenna Reflective Array

Antenna Curtain Antenna

Ferrite or Loop-stick Antenna

Quad Antenna

6MONOPOLE ANTENNA

Monopole antennas consists of a single conductor, such as a metal rod, often mounted perpendicularly on a conductive surface (Ground plane). It was invented by radio pioneer Guglielmo Marconi. It is used for Radio broadcasting.

7DIPOLE ANTENNA

A dipole antenna consists of two straight metal rods or wires oriented end to end on the same axis, with the feedline connected to the two adjacent ends. It is used in radio & telecommunication.

8ARRAY ANTENNA

Antenna Array is a systematic arrangement of antenna elements with a deliberate relationship between their current, forming a single antenna. It is used as radar, satellite communication etc.

LOOP ANTENNA

9

A loop antenna is consisting of a loop of wire connected to a balanced transmission line. It is used in military communication & this enables Near Vertical Incidence Skywave (NVIS) communication up to 300 km in mountainous regions.

OTHER KINDS OF ANTENNAS 10

11APPLICATIONS OF ANTENNAS

12ADVANTAGES OF USING ANTENNAS

Antenna is a device that transmits & receives signals in a free space.

Mechanically strong when mounted on a rigid surface. Antennas have high performance. Low fabrication cost, hence can be manufactured in a large

quantities.

13CONCLUSION

Antennas are very curious devices. From cell phones and televisions to automobiles and the tops of buildings, we see a variety of antennas all around us. They transmit and receive information by invisible electromagnetic waves in a free space. Antennas are very important part of communication systems.