Hi Jonjo, unless you have an extremely advantageous location, an external antenna and mast-head amp! I've a virtually unobstructed 360 degree horizon at 200' asl, and with supplied antenna indoors, get SFA - 3' thick stone walls, with antenna stuck out of top window, onto a bit of flat roof not quite in the clear of the main roof, received a max. of 7 at one time, incl. one travelling out (Fedex cargo) tracked to 140 nm.. I'll be buying a couple of new antennas in the next couple of months, and will post results - totally dependent on getting a good weather window to do any DIY over 15' - very windy place. I'm also looking at making a trio of Slim Jim antennas, one centred 126MHz, one for 160MHz (marine VHF) and one for 1090 - try this link
http://www.hamuniverse.com/slimjim.htmlUpdate @ 1230 just had a quick play, 25 on screen at one time, all to the north, west and south, nothing east and up to 140nm. This is down to the gable roof ridge which is aligned north to south and is behind and 6' higher than the flat roof , just proves the point about height of antenna and obstructions. Polar diagram also confirms this, almost a straight line behind the twig!