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Author Topic: Inveted G5RV Omni  (Read 3457 times)
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« on: February 21, 2002, 05:31:26 PM »

Has anyone tried using an inverted G5RV with wires running N and S and E and W with all wires attached to the same feedpoint? I can't recall of anyone mentioning this and how would it affect the pattern compaired to the regular inverted G5RV?   Bill
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WB2WIK
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Posts: 21753




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« Reply #1 on: February 21, 2002, 06:56:07 PM »

In free space, this makes it more omnidirectional.  However, closer to the earth than "free space," it will behave differently.  You can easily model the difference with EZNEC.  (http://www.eznec.com for demo version)

However, this is also placing the feedpoints of two antennas in parallel, which will halve the feedpoint impedance if resistive, and possibly have less desirable effects if reactive.  The G5RV is normally pretty close to R=50 j=0 at 14.2 MHz.  By placing two of them in parallel, albeit it crossed at 90 degree angles, this becomes R = 25, j=0, so VSWR, instead of being 1.0 would be 2.0.  Not so bad, but worth considering.  At frequencies where the impedance is already low, simply paralleling antennas might make it unmatchable.

WB2WIK/6
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KA4WJA
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« Reply #2 on: February 22, 2002, 03:01:47 PM »

Bill,
While I'm usually an optimist....in this case, I believe the poor performance of a G5RV used in an "inverted v" configuration would follow on to your idea.... (although I haven't modeled your idea...)

Jim, W4THU, has shown in his book, how awful the performance is when using a G5RV as an "inverted v"....
The modeling of a G5RV "inverted v" (on 20 meters) VS.
a 1/2wave dipole shows a "loss" (rather than "gain") of 6db - 13db!!!!  at an "inverted v angle" of 90 degrees....  

Whether this would be show up as bad (or even worse) when used with an additional set of "inverted v" wires,
I don't know...... BUT My guess is that it wouldn't be as bad....

BTW, using a G5RV as an "inverted v" (or any 1/2wave dipole as an "inverted v", for that matter) will provide a fairly Omni-Directional pattern WITHOUT adding any additional wires.....
(Omni-Directional within a db or two...NO deep nulls, nor strong lobes!!!!!)
It's just that the G5RV's performance is seriously reduced when it is used as an "inverted v".....

I hope this gives you something to consider.

73,
John,  KA4WJA
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