Hello all, i just would like any any comments or ideas why am not recieving certain types of aircraft when am at the airport using the supplied antenna. Here are a few types that i don't recieve, EP-3C, AS355 Twin star, SW4 merlin and othe small general aviation ac. etc C172, Piper........ any help would be great, those are the major traffic that we deal with here on my island. Thanks!