Greetings, I am in a particularly sticky situation with one of my two meter repeaters in Lakewood, WA (Tacoma). I have generally great coverage, however there is a very annoying problem with multipath and raspy signals in a large portion of my coverage area. Since the Puget Sound area of Western Washington is very hilly and mountainous, multipath is very damaging to all forms of VHF communication.
Over the years I have read about folks employing circular polarization to overcome fading, nulls, multipath, etc. There is so very little written about this topic in amateur circles so I thought I'd bring it up here and see what I could come up with. In the 80's there was a amateur radio repeater book by a fellow, Pasternak I believe, that took two gamma match style Cuschcraft Four Pole antennas, combined them, and did some magic with phasing lines to end up with a four bay circularly polarized repeater antenna. Unfortunately the description leaves much to be desired, at least for me, so I never built one. If he would have included specifics on phasing line lengths, cable types, etc, the job would have been a whole lot easier. Has anyone actually gone circular with Cushcraft Four Poles, and if so, could you please share it with me and/or this group? I have done some inquiring to commercial companies about a custom built two meter four bay circularly polarized array, but that is entirely out of the question. They want thousands of dollars. There must be an easier (and cheaper) way. Similarly, is anyone in this group running circular polarization on your amateur repeater(s), and if so, could you please share the details in a manner that could be duplicated without a lot of guess work? I know that I could easily solve my multipath problem by installing one or more remote receivers, however I would like to keep that as a last resort and shoot for a circularly polarized antenna system at the main repeater site. I do understand that there is approximately 3 db of loss as a result of this, but that is quite acceptable. The dividends would greatly outweigh the down side. Thanks for any constructive ideas, suggestions, links, etc, that you might be willing to share concerning this situation. Best regards, Gary, K7EK Personal Web Page: www.k7ek.net
