[TowerTalk] XM240 SWR plots

[Richard (Rick) Karlquist]

On 3/25/2018 3:17 PM, Jim Brown wrote:
> It's important to remember that SWR is NOT an indication of antenna 
> performance. It ONLY indicates a match to the feedline as measured in 
> the shack.  It does not tell us that the antenna has gain, nor does it 
> 73, Jim K9YC
> 

Jim is exactly right (as usual).  When I first got my MonstIR up, I took 
advantage of the fact that I could adjust the length of the three 
elements individually.  Just to prove a point, I tuned up the antenna 
the usual way for CW (all 3 elements optimized); then I QSYed the
radio to the phone band.  The SWR was not ridiculously high and a
radio with a tuner could drive it.  I retuned just the driven element to
get the best SWR I could, without changing the parasitic elements.
That improved the SWR somewhat.  However, as expected, the antenna 
suffered a substantial drop in gain and F/B ratio to where it wasn't
much better than a rotatable dipole.

Rick N6RK