I have some doubts
1. Why Wave guide feeders are pressurized generally..???
2.How Electrical length of an antenna is defined ?
3. why Cassegrain feed is used with a parabolic reflector ?

Plz help me know these answers..

 

Hello,

Here is a page with some links :
http://www.educypedia.be/electronics/antennaparabola.htm

There are more antenna topics over there :
Antennas: Antennas general overview Antenna list J Pole antenna Antenna topics Dipole antenna Loop antenna Radar Antenna types: overview Helical antenna Parabolic Dish Antenna Yagi antenna
Greetings,
Bertus

 

I have some doubts
1. Why Wave guide feeders are pressurized generally..???
2.How Electrical length of an antenna is defined ?
3. why Cassegrain feed is used with a parabolic reflector ?

Plz help me know these answers..

Waveguides are pressurized to keep moisture out. This reduces loss for receiving weak signals, and prevents arcing when using high powered signals, as in radar.

The basic half-wave dipole is 5% shorter than an actual electrical half-wave in free space. This is the normal physical length. In English units, the physical length of a dipole is 468/f(Mhz)

Cassegrain systems are designed to make the antenna physically shorter for a given focal length. They can be built mechanically stronger that way.

eric