"Mr Bigchopper (nothing like being modest, eh?)"...
I have a helicopter.. what were you thinking about then?
Thanks for your information, all.
Fitting a transponder isn't entirely practical for my flexwing, believe me! So, primary it is....
" eyethinksy, since when has the position of a transponder aerial had a negative effect on the performance of radar?"...
Well, all antennas have a specific radiation pattern... that is, they radiate more in one direction than another.. this can be made worse depending on how it is mounted to the aircraft itself.. this compromises radar system performance, since the transponder has reduced receive and transmitt performance related to the direction in question. Antennas used for transponders are intended to be reasonably omnidirectional.. that is... until they are mounted adjacent to an aircraft fuz, rather than perpendicular.
cheers
Andy