It's not directly radio related... But one of the talks at @G5BK last week was about adsb (or a-dsb?)
Anyway, I've dug out the collinear I made a while ago, and have iterated from netbook running debian, to a pi running flight aware stuff. Seems to hear OK even from the living room.
Next step will be to move it to the loft and see if it can hear more than 50km