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#2
February 29th 04, 06:03 AM
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(RHF) wrote in message . com...
(John) wrote in message . com... (RHF) wrote in message . com... JD, The G5RV is a good Antenna and an Off-Shoot of the common Dipole. ALL TRANSMITTING THEORY ASIDE: * For SWLs think of the G5RV as a Dual Opposing Inverted "L" Antenna with common mode vertical (dual element) Leg. - Here the G5RV is more Omni-Directional. * For SWLs some specific Frequencies the Top Arms of the G5RV Antenna function like a Dipole that is 'cut' for that Band or Bands. - Here the G5RV is very 'directional' Dipole. Thanks for all the responses so far. Yeah, that "dual opposing inverted L" seems to make a lot of sense. And it is low noise. As for directional properties: I don't seem to notice any. Maybe I haven't bothered to experiment enough; but I've noticed that I seem to receive stations on a par with reception reports I've read here and other places. As for the top arms being "cut" for certain bands; again, maybe I haven't experienced all, but I seem to get all I can get on any band just as everyone else does. Anyways, those are just my observations. I have always been happy with the G5RV. Some day I'll need to get a bit more motivated and stretch out a really long wire and see what difference it makes at my location. Again...thanks to all the replies received. John . JOHN, There is only way that you will be able to "KNOW For Sure" that your current G5RV Antenna is Omni-Directional or very Directional on various SW Bands. Take the G5RV Antenna down; and re-mount the G5RV Antenna perpendicular (90*) to it's former position. Then try listening to your old good stations and next Scan the SW Bands for new stations that you could not hear before. IF - The old Stations are 'weaker' and you are hearing NEW Stations: Then your G5RV is very Directional like a Dipole. However - If the old Stations 'sound-the-same' and you can not hear any New Stations: Then your G5RV is Omni-Directional. iane ~ RHF Will depend on the band quite a bit though. Will always be pretty omnidirectional on the low bands, unless the antenna is real high in wavelength for the band used. "1/2 wave or higher" Max gain will be straight up for the usual heights involved. The G5RV acts pretty much as an 1.5 wl dipole on 20m, and should show broadside gain of 2-3 db over a 1/2 wave dipole. The maximum "clean" broadside gain will be at about 12 mhz. "appx 5 dbi". This is where the antenna is an extended double zepp. The pattern is X shaped on 20m, with less gain. On 21 mhz, you will see an X pattern with about 4.7 dbi in four directions. On 28 mhz, you have a six lobe pattern with max gain in four "x" directions. "about 4.6 dbi". But even with the lobes and gain, it's quite probable you wouldn't totally lose any station when turning 90 degrees, due to ground effects, metal in the area, etc, unless you found a fluke good null by chance. You could peak a few up though, and probably find a few good nulls, if you could rotate the antenna. The G5RV will act the same as any other 102 ft dipole, assuming no feedline radiation. "Which it shouldn't have". If I were to run a G5RV for all bands, I'd feed it with ladder line the whole way to the tuner. I'd dump the coax and choke. Just causes excess loss, and a quite larger chance of imbalance. MK |
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