For shortened antennas such as the MP-1 there is a wonderful information resource in the yahoo hfpack group. They have run a lot of comparisons of portable antennas including MP-1, Buddipole, etc, as well as absurdly shortened versions. They make somewhat serious "antenna range" comparisons to an unshortened reference antenna at the same height. As I recall, losses for a shortened antenna really don't get very significant until you get below about 50% length, all other things, including height, being equal.
I sometimes use my Buddipole for backpacking, either in horizontal or vertical configuration. The standard Buddipole is long enough to be about 50% for 20m. For 40 it is easy to get close to 50% with extra sections and longer telescoping whips. The MP-1 manufacturer produces produces components that are very comparable to the Buddipole ones, suitable for horizontal as well as vertical configurations. In selecting between vertical and horizontal configurations, I always keep in mind something I read years ago: that the overall efficiency of the antenna is influenced by the efficiency of the ground reflections of the waves way beyond the near zone. My recollection is that with poor soil, horizontal polarization has an edge, while the opposite is true for good ground locations such as near salt water. With my local rocky and dry soil, I think horizontal polarization has the edge. Using both halves of the Buddipole makes for a heavier backpack though. A wire dipole laid directly on the dry, rocky ground on a mountain works surprisingly well. Perhaps an endfed dipole would also work well on the ground under those conditions. I intend to experiment more with inverted vee's made of light wire and using lightweight poles for support. 73, Erik K7TV > When the availability of antenna supports is a problem, I > usually opt for my MP-1 system. This system works a lot > better than most people realize, particularly if you add a > section or two under the coil, and spread more radials. > It's still very portable, and very easy to set up. > Sometimes, a vertical is your best option. ______________________________________________________________ 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
