>Pushraft;1403260]Here is an interesting article. I think what they are saying here is that height above ground of a Yagi(-Uda) antenna is mostly the determining factor of launch angle if and only if it is already over about 3/4WL in height. Below that height, boom length also makes a significant difference with respect to take off angle. http://amfone.net/ECSound/K1JJ24.htm This part is probably the most significant to HF using horizontally polarized beams:< ::Actually, the comments made in that article don't apply to HF. The article is about 6 meters, which is 50 MHz, and VHF. It's very different. Remember, 50 MHz and above is VHF, and everything about that involves terrestrial work or the occasional sporadic-E layer (or even more rarely, F2-layer -- that occurs only at sunspot cycle peaks, which we are very far from, right now); but 99% terrestrial. HF is virtually all ionospheric, using a very high layer to reflect signals. There's no "ground wave" to speak of at HF (we can enjoy a little bit of it on 80m and 160m if we use vertical polarization, but that's about it), and "tropo" on HF works, but it's not what we are normally shooting for. We are all optimizing antennas for ionospheric work, and the comments about 6 meter antennas don't apply.