dishes for receiving tv programme are made of fibre or silver, copper is also conducter why it is not used?

Question

why not dishes are silver or gold plated
for better result

Answer 1

The signal from the satellite is a microwave signal of a little more than a centimeter in wavelength. That means they will not pass through any metal with a hole smaller than that dimension, but instead are reflected. Microwaves are reflected from metal very much like light is reflected from metals. The satellite dish that appears to be plastic or fiberglass actually has metal embedded within it. Any type of metal, including copper, will work. The metal most commonly used is aluminum or steel.

The metal mesh is not used because of its conductive properties. Its conductivity is irrelevant. It is acting as a reflector and because of the parabolic shape of the dish is reflecting the signal in concentrated form into the receiver that sets over the front of the dish.

I seriously doubt that any satellite dishes have silver in them, and using copper would be a waste of money, since copper is much more expensive than steel or aluminum. It is even possible to build a satellite dish out of chicken wire or screen wire. The wire is close enough together to reflect the microwaves. However, the shape is critical, and the plastic or fiberglass is designed to keep the critical shape.

Here are some diagrams:
http://www.mlesat.com/antennas.html
The microwave spectrum (in centimeters):
http://meted.ucar.edu/npoess/microwave_topics/overview/print.htm#s1p2
Manufacture of dishes:
http://www.madehow.com/Volume-1/Satellite-Dish.html

Answer 2

the dish is used to reflect the microwaves and concentrate them to onto the central aerial in the dish.Copper as already pointed out absorbs too much of the signal so is not the best material for the dish.Remember the dish is a receiver so you want to capture and then reflect waves into the dish and not relay the waves from the dish but from the aerial in the midelle of the dish

Answer 3

Copper corrodes too easily. Gold and silver are better conductors.

Answer 4

Too expensive. It would be cheaper just to build a larger dish of the cheaper material.

Answer 5

The signal bounces on the surface. copper absorbs too much of the signal that cant be recovered.

Answer 6

copper is too weak to support it's own weight.. aluminum holds up much better and is not nearly as heavy.

Answer 7

energy must be reflected and copper absorbs energy making it less efficent

Answer 8

cuz they didn't feel like it maybe and it would cost more money. duh