Subject: How can I increase the transmitting power of a television transmitter?

I am experimenting with a model rocket carrying a small television camera 
and transmitter I built from a kit.  It works but doesn't have the range I 
would like it to have, since the rocket goes up several thousand feet.  It 
runs on 9-12 volts dc, supplied by on-board batteries. The kit was designed 
for home security so only transmits about a hundred feet. I have tried a 
long antenna but it doesnt seem to make a difference.  Any suggestions 
would be helpful.  Thank you! 

Re: How can I increase the transmitting power of a television transmitter?