I use to put my scaner with handheld antenna wright near my window(wich have an aluminium profile and this thing improves antenna 's features ) that 's offers me a good reception. This position of my scaner (with handheld antenna) was choosen because is a better place for such a kind of feed. I like to underline here, that the distance between my feed and ATC site ( from the place where the controllers are transmitting) is about 5 miles far away (my feed is in Bucharest and ATC site is to periphery of Bucharest). If you would like to listen you will remark the ATC's good quality transmission , having in view that my scaner doesn't use an external antenna.
I wish you good listen!