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#1
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![]() "usmcbrat" wrote in message news:5_cFj.257$rb6.143@trnddc01... ..I'll be persistent and let people here know when I get the plans. I still don't have "plans", but here's a picture. Turns out it was a 3 element. My apologies for such an inaccurate memory. http://img168.imageshack.us/img168/5...ining1shk5.jpg |
#2
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![]() "usmcbrat" wrote in message news:01HGj.3370$rb6.1690@trnddc01... "usmcbrat" wrote in message news:5_cFj.257$rb6.143@trnddc01... ..I'll be persistent and let people here know when I get the plans. I still don't have "plans", but here's a picture. Turns out it was a 3 element. My apologies for such an inaccurate memory. http://img168.imageshack.us/img168/5...ining1shk5.jpg Hi "UMC" Is it practical to mount the antenna outside toe helicopter? I once designed an antenna system for military helicopter VHF homing. I used two dipoles made of foil taped to the plastic windshield. It worked. The idea was/is simple, but you'd need to build a seperate electronic device to go between the antenna and the receiver. And, you'd (of course) need to manuver the helicopter rather than twist/turn the antenna, because, the helicopter would be the antenna. Jerry KD6JDJ |
#3
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![]() I still don't have "plans", but here's a picture. *Turns out it was a 3 element. *My apologies for such an inaccurate memory. How about a small Yagi made with "rubber duckies"? Mark |
#4
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![]() "Mark" wrote in message ... How about a small Yagi made with "rubber duckies"? I admit it, I don't know what you mean. ![]() |
#5
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In article U7YGj.9289$Oj5.166@trnddc06,
"usmcbrat" wrote: "Mark" wrote in message ... How about a small Yagi made with "rubber duckies"? I admit it, I don't know what you mean. ![]() USMCBrat- I think the cubical quad may be the best antenna for your situation, but there are other options. "Rubber duckie" refers to the shortened rubber-coated antenna on a walkie talkie. If several of these were arranged as a yagi, they would not have the sharp points your full size yagi has. Another is called a "Doppler Direction Finder", and requires an electronics package. It has 4 vertical antennas arranged in a square on a metal plate. Take a look at http://www.ramseyelectronics.com/cgi...dd=action&key= DDF1 for an example of this kind of system. The vertical antennas might be "rubber duckies" as well. Fred K4DII |
#6
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Another is called a "Doppler Direction Finder", and requires an
electronics package. It has 4 vertical antennas arranged in a square on a metal plate. Take a look at http://www.ramseyelectronics.com/cgi...dd=action&key= DDF1 for an example of this kind of system. The vertical antennas might be "rubber duckies" as well. Fred K4DII I would also have a search for 'Handifinder', it is a simplified version of the above that uses 2 small loop antennas and is easily hand portable. It is cheap and easy to build and I think kits are available. It does have a 180 degree ambiguity but in real use that is not a great problem. 73 Jeff |
#7
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![]() "Jerry" wrote in message news:SeOGj.4383$Dv5.2658@trnddc02... Is it practical to mount the antenna outside toe helicopter? I once designed an antenna system for military helicopter VHF homing. I used two dipoles made of foil taped to the plastic windshield. It worked. The idea was/is simple, but you'd need to build a seperate electronic device to go between the antenna and the receiver. And, you'd (of course) need to manuver the helicopter rather than twist/turn the antenna, because, the helicopter would be the antenna. Hi Jerry: I guess if the helicopter was specifically part of the searching agency then you could do something like that. I'm not sure if they'd ever do that. The choppers and pilots are usually "on loan" from whatever agency is available to help when someone's lost. The CHP has some, most Sheriff's departments, Feds, Military, State Police, etc. When a person is lost, people seem to come out of the woodwork with the desire to help. That often includes agencies that own helicopters. While I'm now a certified trainer because of my classroom time, I'm still a brand-newbie to search and rescue, and have never been on a "real" search for a missing person. I've located hidden transmitters on dozens of occasions, either hidden on a person who was part of the training, or just plain hidden. If I can get within a couple of miles of one of the transmitters I can normally go straight to it, even if it's down a drainpipe, under a bridge, or behind the coffee maker in a restaurant... it doesn't really matter much where it is located. More of our training is related to understanding people with Alzheimer's and other forms of dementia than is related to actual radio work, and rightfully so. There's much to study on the human side of it. One of my greatest fears now is that I'll search for a person who is at a significant danger of being injured and is lost in a giant crowd of people, and they don't want to be found. I feel uncomfortable "pointing" the antenna around crowds of people for obvious social and psychological reasons. An example might be someone "lost" in Time's Square on New Years Eve.... the very thought shivers me timbers! ![]() Luckily, being from Central California, I'll be much more likely to be searching orange groves than giant crowds. Interestingly, orange groves absorb a signal much more than I had thought they would, and, the signal propagates much better down the rows than across the rows. The trees were laden with oranges and I could barely hear a signal from one of our guys who was purposely trying to avoid us. He was literally 5 or 6 rows in (across) and I could hardly hear the signal. Once we got to the end of the grove and got to look down the rows, the signal jumped. Thanks again for all of your help! MB |
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