Topband: small antennas

[George (K8GG) & Marijke Guerin]

David, WX7G asked:

Subject: Topband: small antennas


> How many of you operate topband with small antennas? Perhaps we can get a
> dialog going on how to do this successfully. I presently use a 22' top
> loaded vertical that will soon grow to 33'. For contests I sometimes use a
> 123' balloon vertical so I do know the relative difference is substantial; 
> 9
> dB between it and the 22' antenna.

David, et. al.,

I would top load whatever vertical you can erect.  Toploading a 33 foot mast 
will be about 3 times as effective as bottom loading the mast.  If you 
cannot run out enough wire to get the resonance down to 160 meters, then put 
a loading coil at the top of the 33 foot mast and then add some top loading 
wires.  The bandwidth will be narrower but the signal strength will be about 
the same.

The antenna will have a low feed point impedance over ground, so you will 
need a transformer or an L-network to bring the impedance up to 50 ohms.

Also put out as many ground radials as possible, even if they are only 1/10 
to 1/8 wavelength long.

GL & 73,

George    K8GG