Going back to my early days in FM, we used to play around with these. It seems to me it should be eminently doable to put together a basic RDF system that doesn't need GPS or Cell Signals. It wouldn't be long range, but might be useful within that "last" 1/4 to 1/2 mile. Using a small, self-powered FM transmitter, a simple wire antenna could be run around the landing struts on the bird. Then, a T.D.O.A. (Time-Difference-Of-Arrival) detector. like the "HANDI-Finder" connected to an FM receiver could be used to home in on the FM carrier. The HANDI-Finder Kit is $28, and the Transmitter could probably be built for half that. Transmitter Instructable: http://www.instructables.com/id/The-Ult ... ansmitter/ HANDI-Finder page: http://www.handi-finder.com/ Thoughts?