Topband: Strange resistance between Beverage ground rods

[Greg - ZL3IX]

Hi Herb,

I came across this problem when I first started using Beverages in 2008. 
I have come to the conclusion that the DC resistance measurement is 
corrupted by electrochemical effects between the grounds, ie potential 
differences. I then changed to an AC measurement. I made a simple 
100-or-so Hz oscillator using an op amp and  I put this between the two 
wires in parallel at the feed and the ground. There is a 100 ohm 
resistor in series. I measure the AC voltage across the Bev and the 
voltage across the resistor and thus deduce a loop resistance through 
the ground.

I have been doing this measurement once a month ever since, irrespective 
of whether I think the performance on 160m has changed or not.

73, Greg, ZL3IX

On 2016-11-16 03:20 a.m., Herbert Schoenbohm wrote:
> I have reflection transformers at the end of every two wire Beverages 
> which I try to test by measuring the wires on the feed end. I remove 
> the transformer from the two wire WD1-A and check the resistance 
> between the two wires which tells me that through the reflection 
> transformer I have continuity. It measures about 40 ohms wire to wire, 
> this is done when I notice any performance change of the antenna. Now 
> come the next test that baffles me completely.  When I measure from 
> either wire to my ground rods alone, to see what the return resistance 
> is, I get reading in the vicinity of 20K  across the 900 foot run.    
> I understand that if the reading was very low it would defeat the 
> whole Beverage principle.  But is 20K Ohms reasonable, very good, or 
> marginal?  I use three foot foot rods at either end and when I pull 
> one out yesterday before moving it the bottom 1/4 was moist and muddy. 
> That Southern end of several reversible Beverages  is located about 
> 100 feet or less from a salt marsh or salt pond.  I also have to such 
> antennas made up of ladder line a DX Engineering components.  They all 
> appear to be working well even though large grass has reach and 
> covered portion of some of them.
>
> But my question is what is a reasonable or good return ground 
> resistance for a 600' or 900' Beverage.  I haven't found any sources 
> of information expect the saying that the higher Resistance the 
> better. Is this correct?
>
> Herb Schoenbohm, KV4FZ
>
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