Topband: Sharing radials??

k3bu at k3bu at
Thu Sep 28 23:56:22 EDT 2006

 Kenny K2KW wrote:

> As the purpose of radials is to minimize current into the 
> ground, a neighboring radial system will help. 
> I saw this when doing some work at K6KM's QTH. We had an 
> elevated 80m wire half wave vertical hung off one tower, with no 
> ground screen. It heard well, but didn't transmit well as 
> compared to a reference dipole.
> I then tried to shunt feed another tower on 160m about 130' 
> away. We had laid 36 radials around the shunt fed tower, and 
> the tips of the 160m radials just reached the bottom of the 80m 
> half wave vertical. These radials were in no way connected to 
> the 80m vertical as the 80m wire terminated about 4' above the 
> ground. The 80m vertical now transmitted MUCH better, and you 
> could also tell the RX performance improved too (as compared to 
> a reference dipole).

I will second that!
What it does, it places the "perfect ground" in particular direction, which helps efficiency by minimising ground loses and pulls the lobe down close to horizon and extends it (more gain) at low angles. This is especially beneficial at the low in sunspot cycle, when the atmosphere and layers are compressed, at lower heights and we are propagating at lower angles.
W8LRL's 3/8 vertical with 360 3/8 radials is good example of the above - extending "perfect ground", raising and extending the high current point and producing LOW angle lobe that is missing in conventional quarter wavers. Being positioned on a good soil small hill with slope in all directions is helping even more. Modeling might not show EXACTLY what is happening in the real life, I have experienced it at W8LRL and K2KW's experience confirms it. Some gurus might have a problem swallowing it, but the reality speaks for itself. 
73 Yuri, K3BU

Yuri Blanarovich, K3BU

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