Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

What is difference between the miltary radar in 1940's from commercial antenna that is for the use of TV?

I have read article from some of the WW2 history website that call the German radar the antenna, so does the WW2 radar have features that is more powerful than today's antenna

share|improve this question

2 Answers 2

up vote 2 down vote accepted

The main difference is that the radar produces a collimated one-directional beam, going out in one particular direction, while the radio station broadcasts in all directions.

The radar does this in order to scan the sky. When it sees a reflection, it knows the direction from the direction it was transmitting. In the 1940s, you would do this with a rotating parabolic reflector, which redirected the outgoing radar waves in one direction. But the modern approach is to do it without moving parts, by using multiple antennas and adjusting the phase difference between them to have constructive interference in the direction you want to scan. Then you don't need mechanical motors.

share|improve this answer

All antennas are designed to emit or accept electromagnetic waves.

The differences in size depend on different frequencies of the EM wave used as signal carrier, since the size has to do with the wavelengths used.

Radar frequencies and Radio TV frequencies overlap, and the divisions are for convenience and specialization of purpose: radar wants to "see" the reflected wave, whereas radio and TV emit to receptors.

So the answer is: no difference except that which comes from progress in technology and political decisions of band sharing.

share|improve this answer
    
This is true, except for the practical difference of collimation. –  Ron Maimon Jul 22 '12 at 7:50

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.