Hi Helen,
I hope and bet that you meant you "do a steep banked turn at 60 degrees" not "at 360 " . <g>
Either that or your capabilities and your aircraft are far more acrobatic than most of the rest of us. 
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I'm not an avionics/radio guy (so take what I say next with a grain of salt) but my electronic and radio knowledge (ex-physics major and computer tech) isn't _totally_ absent, so FWIW here's my take
Seem to me like you WANT your ELT antenna on top. Most crashed planes (the time you'd MOST hope your ELT is received) are on the ground right side up and the search planes homing on your ELT are above you.)
A final thought: There's something to be said for carrying a pocket-type PERSONAL locator beacon (PLB).
They cost a tiny fraction of what the new aircraft ELT's ($1000 to $3000) cost, and unlike the older ELTs that transmit only on 121.5-MHz (and are not picked up by the satellite) that many of us have in our aircraft a PBL works on the newer 406-MHz that the satellite system (NOAA Search and Rescue Satellite Aided Tracking (SARSAT) ) picks up even if you're stuck in some steep remote valley.
You can get a PLB for a little over $200 whether you buy at a sporting goods outlet like REI or an aircraft source like Spruce.
If like, me, anyone else has one of the many older ELTs that transmit on 121.5 you might note this comment from AOPA:
" It is important to note that after 2009, existing 121.5-MHz ELTs, although still legal from the FAA's perspective, will provide extremely limited assistance if an aircraft crashes, especially in a remote location."
As for the net pros and cons of positoining the ELT antenna – I'd say check with folks/techs in an avionics forum:
Just google
avionics forum
and you'll find dozens of them.
Alex
"Helen Woods" Helen_Woods@verizon.net hwoods4421 Wed Apr 4, 2012 5:26 am (PDT)
I don't know about legality, but I do know something about
functionality. It's not going to do you much good up there. You mount
a transponder antenna on the belly for the same reason you mount a GPS
antenna on the roof - you want have an unobstructed view of what it is
trying to talk with. Here in the DC SFRA we don't go anywhere unless
ATC can pick up our transponder. Even mounted on the belly, the slant
range, especially on a low wing plane, can cause problems with ATC
picking up you signal. It's not uncommon for me to have to do a steep
banked 360 especially at low altitude for them to get my signal. I
can't imagine them ever getting my signal if the antenna was on the roof.
Helen
On 3/26/2012 4:11 PM, ron_d_hill wrote:
> Is there any legal reason why I can't install my transponder antenna on the TOP of the plane between the wings?
>
> Is there any legal reason why I can't install my transponder antenna on the TOP of the plane between the wings?
>
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