>>>From: "Peter Rattenbury" <ratten_at_uow.edu.au> Evan, Are you looking to make up a temporary or emergency VHF antenna to pick up the international marine VHF frequencies...? [snip] Remember that this emergency antenna is less efficient on transmit than the rubber ducky, especially if you are using several metres of coax.<<< Sorry, I'm on the digest version of Paddlewise, so I just got your posting. The primary idea I had was an antenna for emergency transmission, presumably in the neighborhood of 157 MHz. Secondary use would be to improve reception in remote areas. However, if as you say, this arrangment works less well than the rubber ducky antenna for transmission, then there's less incentive for me to do this. Are you saying the quality of the transmission would be poorer, even though the range would be farther (due to being elevated higher)? I've been having a hard time finding a sketch of a J-pole antenna, other than the kind of home-builts that people make out of copper pipe and mount to their homes. Also, the terminology for things like "tap", "stub", and "radiator" does not seem to be consistently used with the sketches I was able to find. Thanks Evan Dallas Woodinville, Washington *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
For one good version of the J-pole that is very portable see; http://hamgate1.sunyerie.edu/~larc/pocketJpole.htm A Google search on "twin lead J-pole" (without the quotes) will give you many more sites. The J-Pole will outperform a rubber duck in nearly ALL cases. Even the loose from the coax is offset by the added height of the antenna. With RG-58 coax you would need to have more coax than you want to carry to make the j-pole less efficient than the rubber duck. For emergency antennas I usually use RG-174 about 20' long and it is FAR better than the rubber duck. I use these antennas on Ham radio and marine VHF and they work very well. michael N6CHV Evan Dallas wrote: > Sorry, I'm on the digest version of Paddlewise, so I just got your posting. > The primary idea I had was an antenna for emergency transmission, presumably > in the neighborhood of 157 MHz. Secondary use would be to improve reception > in remote areas. > > However, if as you say, this arrangment works less well than the rubber > ducky antenna for transmission, then there's less incentive for me to do > this. Are you saying the quality of the transmission would be poorer, even > though the range would be farther (due to being elevated higher)? > > I've been having a hard time finding a sketch of a J-pole antenna, other *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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