Topband: Question abt gain in bi- vs uni-directional Beverage

[Gary Breed]

Chuck and all,

Very short "Beverages" can work quite well down to 250 or 300 feet,
but they almost always require a low termination resistance. A reactive 
(inductive) termination can improve the f/b further, at the expense of a 
broader front lobe.  Patterns of Beverages less than one wavelength long 
become cardioid rather than figure-8 as they get shorter.

I have had success in the past with 300- to 350-foot beverages. I started
with a 390-ohm termination, but did not get good f/b until I paralleled
another 390 ohms with it to get under 200 ohms. One of them worked best
with the far end connected directly to the ground rod -- a termination
equal to conductor and ground losses. 

According to modeling, Beverage-like wires less than 250 feet long cannot 
achieve a useful pattern with simple resistive termination. But, with a 
resistor+inductor termination, you can get a good cardioid pattern. 

73, Gary
K9AY





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