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On Apr 16, 6:16*pm, Jim Lux wrote:
But just feeding the end of a 1/2 wave wire sticking in the air is asking for difficulties. *Your coax is nominally 50 ohm sort of impedance, and you'd be end feeding a dipole at a high Z point (a thousand ohms, maybe). Feeding it would be fairly easy.. But.. Just because it's a half wave will not mean that there will be low ground losses if ground mounted. You would see less ground loss than a ground mount quarter wave, but it could still be an issue. Note that most broadcasters who run half waves, also use a set of half wave radials. I'd probably rather use 32 ft masts supporting self supporting 32 ft radiators, and use a few sloping radials as radials, and also to double as guy wires. That will work fairly well with as few as three radials. More to be optimum, but this is field day.. :/ |
#2
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#3
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On Apr 29, 1:03*pm, Jim Lux wrote:
wrote: On Apr 16, 6:16 pm, Jim Lux wrote: But just feeding the end of a 1/2 wave wire sticking in the air is asking for difficulties. *Your coax is nominally 50 ohm sort of impedance, and you'd be end feeding a dipole at a high Z point (a thousand ohms, maybe). Feeding it would be fairly easy.. But.. Just because it's a half wave will not mean that there will be low ground losses if ground mounted. You would see less ground loss than a ground mount quarter wave, but it could still be an issue. Note that most broadcasters who run half waves, also use a set of half wave radials. I'd probably rather use 32 ft masts supporting self supporting 32 ft radiators, and use a few sloping radials as radials, and also to double as guy wires. That will work fairly well with as few as three radials. More to be optimum, but this is field day.. * :/ And would strongly resemble the radiators at WWV... If you do this, you'd put the AH4 at the join point too. *For FD, you might want to have the bottom 8-10 feet of the guy/radial be an insulator, so that nobody touches the HV part of the antenna. It would be above ground level with a 32 ft mast. So that would be no problem. I've used that antenna here at the house, except I had the 32 ft radiator on a 36 ft mast. I used four radials and sloped them down and tied off to trees, fences, whatever.. I would not use the AH4 tuner. No need.. The antenna would be resonant. It would work pretty well on longer paths at night. The same antenna can also be used for 17m if you add a matching coil to use it as a 5/8 wave. I had a 24 volt relay rigged up at the feed point of mine, and could switch from the shack. |
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