> For comparison, a 2 element quad, with a boom length of > about one meter, has only 7.07 dB gain, and although the > four element quad gives you an additional 0.8 dB gain with > the additional element, it comes at a high price -- the > boom is almost 30 feet long! > > For a Yagi to achieve gain similar to a three-element > quad, you need to double the boom length. If you look at > the marvelous spreadsheet that VE7BQH posted a bit > earlier, you'll see that single Yagis of about the same > boom length as the three-element quad offer free space > gain of only about 5.5 to 6.5 dB, and Yagis with about > 9.5dB have boom lengths of roughly 1.1 wavelengths, more > thn twice as long as needed for a comparable gain quad.
Actually not. A three-element yagi on a 0.4 wl boom can easily have 9.4 dBi gain in freespace. I just confirmed that by pulling up the model for my 40 meter 3-element yagi antennas, which models at over 9.4 dBi in freespace with a 0.4 wl boom. There is virtually no difference at all between a quad and yagi for gain. How they work is more how they are optimized than anything else. There is very little difference between them. The quad trades H-plane beamwidth for E-plane beamwidth, and that difference goes away even more as the antenna is made longer or placed over earth. Either can be slightly better, or slightly worse, depending on height when optimized. When one is "messed up", it will naturally look worse. http://www.w8ji.com/quad_cubical_quad.htm 73 Tom ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
