Topband: Where to ground the Beverage feedline?

ZR zr at
Tue Nov 20 10:41:44 EST 2012

----- Original Message ----- 
From: "Tom W8JI" <w8ji at>
To: <topband at>
Sent: Tuesday, November 20, 2012 9:00 AM
Subject: Re: Topband: Where to ground the Beverage feedline?

>> Um -- what did you say was the typical skin depth of soil at 2 MHz? 
>> Somehow,  I seriously doubt it was down that far. :)
> Common mode suppression requirements depend on things:
> 1.) The sensitivity of the antenna to all signals, either bad unwanted 
> signals like noise or good wanted signals. This is the good signal and bad 
> noise power output of the antenna.
> 2.)  The level of unwanted signals and noise fed down the feeder towards 
> the antenna.
> 3.) The ratio of series and shunt impedances along the system, but only 
> **if** the system has enough unwanted CM junk to overcome antenna signal 
> power.
> For some reason beyond my understanding, I think we are going far over the 
> top of what is reasonable....and it is getting worse.
> I was at a friend's house and he told me about installing very long bead 
> strings in Yagi antenna feeders. Please, let's all stop this needless bead 
> insanity and get back to some common sense.
> Any conductor very near earth for a long distance has considerable 
> attenuation along the conductor. If it didn't, we could bury our NVIS 
> antennas or run longwires laid right on dirt with high efficiency. It's 
> all about ratios everywhere in the system, including the CM injected and 
> signal level sensitivity of the antenna.
> I make enough measurements of antennas here every year, some right in my 
> driveway near noise sources, to know when something is getting overblown.
> 73 Tom

Its easy to see the attenuation; just compare a 160M dipole at 30-50' to one 
on the ground and also compare resonance points.
On my rock pile its significant and crud pickup goes way down. In the desert 
it may be less significant.


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