Topband: 43’ 80 Meter Vertical

[Richard (Rick) Karlquist]

On 4/10/2021 1:16 PM, Chortek, Robert L. wrote:
> Hoping to get some guidance from the antenna gurus here.
> 
> 
> Can someone tell me if I added two top hat wires 16 GA THHN sloping at 45 degrees “about” how long they would need to be to resonate at 3.545 MHZ.
> 
> Bob/AA6VB
> Robert L. Chortek

After SWR, the most overrated goal for ham radio antennas is
resonance.  You should use the amount of top loading that
maximizes the radiation resistance.  Then put an appropriate
reactance in series with the antenna to provide a resistive
load to the transmitter at 3545.  The reactance may be turn out
to be inductive or capacitive.  You will also want to make
the series reactance variable somehow unless you only ever want to 
operate on 3545.

You would also be advised to use 4 top loading wires instead of
just two.  There is a substantial advantage for 4 vs 2.  Beyond
4 top wires (say 8) the benefits aren't worth the trouble.
This is explained by the fact that 4 is the maximum number of
top wires that don't couple to each other.

It is also advantageous to pull out the top loading wires to
a more gentle slope if you can.

You can use bare aluminum electric fence wire to reduce weight
and wind loading on the vertical.


73
Rick N6RK