[Nisgeis]

The longer the radar waves the larger the receiver needed to get directional information. The early air search radars had large 'mattress' type ntennas that looked like a sping mattress without the padding. The antenna had to be that large to selectively receive the directional information. Early night fighter radar was also omnidirectional. They sent out a pules in all directions and they got a return (or bang as they called it). The bang from the ground was so large that it blocked out all other signals, so effectively their maximum search range was the same as their height. Early on, the new radar wasn't understood and if the target's range was increasing and they increased speed, then the Germans would also increase speed even more. It took a while to work out that they were in fact in front of the enemy and were pulling away from him. They used it because it was the first sytem to be developed and it was the only thing they had.

Only when centimetric radar was invented was it possible to have a system small enough to go in an aircraft and submarine.

If you are at sea level then you get a massive return from the sea at close range, so you can't use your set at very close ranges as the return from the sea blanks out anything near you.