Topband: Circularly Polarized Receive Antenna

[Rick Kunath]

This is a very interesting idea Brian.

Have you thought about taking the idea to the next level and using 2 
antennas with one vertically polarized and one horizontally polarized 
and feeding these via a dual-channel SDR to Linrad?

I have done this for CW and on mediumwave for years (using small flag 
antennas and LoG loops feeding an SDRplay RSPduo) now and Linrad is an 
amazing piece of software, I would say the most advanced SDR software 
there is and it's been that way for a while.

Linrad can use it's automatic adaptive polarization function to optimize 
a generated polarization based on the input from the 2 antennas. It'll 
generate linear, elliptical or circular, of wither handedness (LH or RH) 
and any polarization in between and you can see all of that going on 
with a phase scope that is built in. It also has the capability to lock 
the adaptive setting and there are a few handy presets, one that allows 
you to invert the optimization. When you do that it eliminates the 
dominant signal and leaves the DX underneath it. It al;so has full 
manual phasing adjustment ability, three saveable presets that work like 
radio buttons to recall 3 phase and amplitude sets of settings.

Additionally it has synchronous and even better coherent detection 
capability to allow for even more tools to dig deep into the noise or 
work with reducing its effects. It has a wider coherent mode to create a 
3d soundscape in your headphones that helps with noise, a CW mode that 
spreads the signals across a soundscape too, an X+Y mode to let your 
head handle the logic of your ears, and a normal narrow CW mode and a 
weak signal CW mode that also has AFC to keep the signal in an extremely 
narrow filter.

It has a dumb noise blanker that works well and is usable on automatic 
or manual modes. And a smart noise blanker that works even better and 
operates in a subtraction mode. You can use both at the same time.

Adjustable filter bandwidths and shape, a second narrower carrier filter 
for those modes that use one, insertable adjustable notches, and either 
a manual or an automatic notch mode that will kill any continuous 
carrier. It's got an adjustable delay function on the audio that I find 
useful sometimes in SSB to help dig deeper.

It will operate on either the time domain or the frequency domain, this 
is selectable.

And lots more.

I thought it might be worth mentioning this because it would be the 
perfect thing to feed your antenna array into.

Rick Kunath, K9AO\