and finally my antenna moved to the roof
radio reception not bad for a sunday
edit: here are two vrs range plots ran about 3 days in parallel - before (attic-antenna) and after (roof-antenna):
edit 2: here is the ads-b receiver. as the antenna sits upon the sat-dish the 15 feet cable ends where the satellite-hub is connected - and that’s where i simply put the raspi at 
as the site with roof-antenna now runs since a couple of weeks i’m quite happy with the results. especially the range and message-count from higher distances improved to about 800.000-900.000 positions per day with this range spread:
