Topband: broadbanding an L

Bob Eldridge r.c.eldridge at ieee.org
Fri Dec 31 16:21:36 EST 2004


At 19:07 2004-12-31 +0000, you wrote:
>Don't forget that sometimes increased bandwidth indicates losses within 
>the system.

That's true, but sometimes a tradeoff is useful. Last week my horizontal 
loop showed 1.5 SWR right across the band. It is normally about 25 kHz 
bandwidth. Signals didn't sound bad, and I worked a couple of JA's.
When it was light I plodded around in the snow and found the wire had 
drooped and was in the branches of an evergreen. I freed it and it came 
back to normal. But it had worked.

 >infamous Maxcom antenna matcher, which was essentially a dummy load 
with >nonresonant antenna wires attached. The wires radiated enough rf to 
produce a >detectable signal . . .

On some bands that antenna was only half an S point down from a dipole. A 
terminated rhombic loses about a third of the applied power in the termination.
The resistor gets warm in a T2FD, but the radiation is more than "detectable".

Just depends what the main objective is. The loss is there, but sometimes 
it helps.

Bob VE7BS




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