Wednesday, April 1, 2009

In the middle

I have been discussing my antenna idea with my buddy K3RR. and he was describing his experience with a 4 square he had constructed where he brought all 4 feedlines into the shack and did all the phasing in the shack itself. This way he could change the phasing and retune the beam from the easy chair. He wondered to me about doing the same thing with my idea, just bring several feedlines into the shack and do the signal analysis from the easy chair. Visions of 8 foot tall reels of coax jumped into my head when ever I think about it.

He came up with an example, from K1LT's website Here is .pdf of K1LT's interesting version of the RX antenna I have been thinking about.

If you have a chance go read about this amazing design read about this. It uses 2x4 endfire elements for a total of 8 elements

Also take a look at his continued iterations on improving performance. It shows some of the practical reality of building such a complex antenna. Part of the reason I want the RX at the base of the antenna is to do away with all the vagaries of inversion transformers and miles of coax and the like and do what needs to be done in software. The thing that captured my imagination about SDR is the notion that to go to SSB from DSB all you have to do is set all the values of one side band to zero, IN SOFTWARE. With my old HT-37 phasing rig the side band was set to "zero" by a passive phase shift network in the radio. It worked to about 20 or 25 dB of supression and then the vagaries of discrete components (like tolerances) took over and the rest of the canceling was lost. I think the sooner you get to memory with the data the better

Also take a look at how he taught himself about digital radio

Very interesting