[TowerTalk] Bev with parallel gnd wires

[Tom Rauch]

> Misek's W1WCR book "The Beverage Antenna Handbook" states the
> following:
> 
> "My work with wave antennas indicates that wave antennas should be set up
> over as nearly lossless ground as possible.  Accordingly, my have antennas
> have parallel ground wires installed along their lenghts in order to
> minimise ground losses"
> 
> This seems to run contrary to ON4UN's book which shows much less
> signal output for highly conductive grounds.  I gathered that Beverage
> antennas actually worked better over poorly conducting ground.
> 
> Question:  Has anybody in practice used these parallel ground wires?

Yes, and it made the antenna a bit less sensitive and directive 
when I compared two antennas..one without the wire and one with 
it.
 
> The reason I ask is that Misek claims that lossy ground can cause
> seasional and even daily variations in antenna impedance.  

He probably has very poor grounds at the ends of his antennas. My 
antennas are stable as can be from summer to winter, and dry or 
rain. The only thing I have trouble with are ground connections 
changing resistance. With a six foot ground rod, I measure about 
150 ohms of RF resistance on 160 (and some inductive reactance) 
in dry weather. After a good rain, it can drop to 60 or 70 ohms (with 
a bit less inductive reactance).

Because of that, I put two or three radials at the termination end of 
each Beverage.     

> notice the difference between soaking wet/dry days in directivity. 
> Maybe Misek's ground wires will reduce this effect.

Yes, you will have poorer directivity all the time if you follow his 
advice..unless your grounds are so poor that they are changing a 
lot with weather. In that case the small loss in sensitivity and 
directivity from the added wire could be offset by the ground wire 
helping you get a better termination. 

Beverages seem to change in performance anyway, because 
ionospheric conditions vary. Some days the wave angle is just 
right, and there is little multipath, and I see 15 dB or so of F/B. 
Other days, or other hours of the same day, I might only see ten 
dB F/B. 

It's tough to sort out what is changing without measuring 
impedances.


73, Tom W8JI
w8ji@contesting.com

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