what is the use of waveguides ?

hello

I have searched throw the internet , all resources explain in details
the specifications and theory of operation of waveguide.

These resources mention something about waveguide advantages like
being capable of transferring huge amount of power with low or no loss
and many other


but I just cant imagin the use of it , as you know these devices are huge in
size and I have never seen a waveguide taller that few ten centimeters .

The rest of the system - the circuit - is a transmission line ( usually a coaxil)

So what is exactly the use of waveguides ? as a matching devices between
Transmission line and antenna ? or what ?

The use of the waveguide is exactly what the name tell. It is kind of transmission line and usually use for transmitting significant power on frequencies where coaxial cables have big loss. Antenna feeders are typical example of waveguide usage.

Thanks for the reply , i conclude the following :

1 ) the waveguides are used in limited distances due to thier huge size.
For example , as an antenna feeder .

2) If we need to guide the wave for a long distance ( as the signal coming
from the dish to the receiver in every home ) then we should use Transmission lines

right ?

a waveguide can also be a HPF... in a sense

Hi allko,

have u seen this?

hxxp://en.wikipedia.org/wiki/Waveguide_(electromagnetism)

If I have helped you please click the helped me button, please

thanks,

all the best

similar to coax but in high frequencies.

Not exactly right.

1. Size of the waveguide depends on wave length. For the frequencies when waveguides are used their size is usually not huge.

2. Signals from dish to receiver in home does not travel through waveguides for another reason. Dish has special downconverter called LNB that transfer signals to lower frequency in the range of 1.5 GHz. For this frequency coaxial cable is better than waveguide and signals are delivered to the home through coaxial cable.

3. Transmission lines do not used to long distance transmission of high frequency energy. When transmitter is far from antenna it is better to install the last stage of power amplifier closer to antenna than use long transmission lines. There are some exclusions of course like special leaky lines but it is not what you asked.

thanks guys for the replies .

(my previus post was not complete , i have edited it and added "then we should use Transmission lines
"

So lets say you are doing a job in NYC, and you take a coffee break, and as you are walking down the street you get mugged--you can always slip a 24" straight section of WR280 out of your briefcase and beat the mugger senseless! Very useful stuff!

hi,

adding to this, waveguide can also be ANTENNA, it can radiate very well when it is open ended.............

There are N port junctions that only waveguide can do. One is the "magic T" hybrid. Horn antennas are fed with guide. Circular guide can be used in rotary joints.