Just found this on Spektrums web site:
Don't point your transmitter antenna at the aircraft
The antenna output is "apple" shaped - that is to say, the lowest output comes directly out the tip of the antenna. For maximum output, keep your antenna away from the model.
Do point your transmitter antenna vertical
You don't fly over your head, do you? Unless you're flying directly over your head, orienting your transmitter in a vertical position - no matter what way you hold your transmitter - will provide great results. How big a deal is this? For most flying, it's a non-issue. But for optimization, keep the antenna from being pointed at the aircraft.
Why it matters
Our lead engineer says the radiation pattern from the Tx antenna is apple-shaped - the least output is out the tip of the antenna.
http://www.spektrumrc.com/Community/...Practices.aspx