Like the WB2 mentioned, I also have a loop...triangular in shape, total length of 300 feet. This antenna exhibits INSANE gain on 10 and 15 meters. With 2 or 3 watts, I can work DX on the first or second call. If the station CAN'T hear me, it's either because someone called him that I can't hear, QSB, or a pile-up. Normally though, it's outstanding. What's more, a local ham buddy of mine worked a Belarus station that wasn't running much power...so he was faint at best. My pal, Peter, has a BIG tower and beam, and I could hear BOTH sides of his QSO. Let's just say he was pretty shocked when he found out that I could hear him.
As I've said before...in the almost 17 years I've been a ham, I wonder daily how I ever survivied without a loop.
John
KB2HSH