Distance two antennas should be apart
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| Apr 12th 2014, 18:32 | |
WV0lTotal Topics: 0 Total Posts: 0 |
I currently have a G5RV Plus antenna that I use for HF and 6 meters. However its 6 meters performance is not to good and at the high end of 6 meters the SWR is to high even with the antenna tuner. So I was thinking of using one main coax for most of the run to the antenna(s) and putting a duplexer to split off the 6 meter band and feed it to a 1/2 wave dipole for the 6 meters. So can I "hang" the two antennas in the trees together (say inches apart)? or would that interact even though only one would be active at a time. How far apart would they have to be? If they were perpendicular (90 degrees) to each other would that make a difference? or can I get away with say maybe 45 degrees from each other? Dealing with CCRs. |
| Apr 13th 2014, 01:45 | |
aa6eTotal Topics: 0 Total Posts: 0 |
The antennas will interact if they run parallel, but maybe not too badly. Spacing shouldn't matter very much. You may have to adjust the length of the 6M dipole to get it to resonate where you want. The interaction is much less if the wires are at right angles, and you would get an intermediate case with 45 degrees. You could try just tying the 6M dipole across the existing G5RV feed point, making a fan dipole of sorts. The ladder-line matching section will probably be wrong for 6M, but it might still be worth a shot. It would save you the duplexer and additional coax. This can all be modeled with EZ-NEC, if you want to get into that (fairly tricky) software. 73 Martin AA6E |
| May 13th 2014, 15:32 | |
N4ZAWTotal Topics: 0 Total Posts: 0 |
Something that is still stuck in my memory from my CB days is to "avoid increments, or multiples of a desired resonant wavelength" when spacing antennas. And I've been pretty-much living by that formula since. Preferably, and if space allows, (which it seldom does), the interaction greatly diminishes over one half wavelength separation. I've used a 40M dipole that acted more like a 2element beam due to it's proximity to an MFJ G5RV... The thing talked into Texas just peachy -- but Georgia was in a "null". If you run a resonant ground counterpoise wire slightly to the downward side of a dipole a quarter-wavelength up, you can make a very nice NVIS out of it, with a mean directional "lobe"... I found that out the hard way too. And I kept it because It worked great! |
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