ADVANCED COMMUNICATION

 RADAR COMMUNICATION:

Radar is a contraction of words radio detection and ranging.
It was first developed as a detection device to warn of the approach of the hostile aircraft and for directing anti aircraft weapons.
Radars are classified into 2 types
according to function 1. civilian radars 2. military radars
according to wave forms 1. cw radars 2. pulsed radars.

SATELLITE COMMUNICATION:

A Satellite is simply any body that moves around another one in a mathematically predictable path called orbit.
a communication satellite is a microwave repeater station in space that is used for telecommunication, radio and television signals.
working:
two stations on earth want to communicate through radio broadcast but are too far away to use conventional repeaters.the two stations to use satellite as relay station for their communication.
one earth station transmits the signals to the satellite that transmitted frequency is called uplink frequency.
the satellite transponder converts the signals and sends it down to the second earth station. this frequency is called down link frequency.
types of orbits:
GEO: ~360000Km from the earth.
MEO: 6000 TO 20000Km.
LEO: 500-1500 Km.

SEMICONDUCTOR MICROWAVE DEVICES:

component                               operating frequency
PIN Diode                                          700GHz
GUNN Diode                                     4-100GHz
IMPATT Diode                                   3-100GHz
SHOTTKY Diode                               3-100GHz
TRAPATT Diode                                3-50GHz


posted by onteru mamatha L/ECE