Short Range FM Propagation

[DDDave]

Hello from Melbourne, Aust.

I am trying to build a short range, FM transmitter for University, and I am having some problems determining the O/P power required.

If my range is predetermined (say, 150 meters), what formula do I need to find the power out of the antenna to solve this problem?

(88 - 108Mhz, if this helps...)

Thanks in advance.

[5B4AJB]

That's a good question, maybe an antenna modeller utility could shed some light on it:-
http://www.eznec.com/

On the other hand, I've built a few of those things in the past - you should be aiming for 100 - 250mW from the transmitter into a simple dipole antenna for that kind of range.