On 7/30/07, david.hagood at gmail.com <david.hagood at gmail.com> wrote: > Does anybody know how the antenna in the N800 headphones is implemented? > Are they using the ground conductor as the antenna, are they using the two > headphone lines as a dipole antenna, or what? Using the ground connector wouldn't really work since I believe it's directly connected to "system" ground and wouldn't produce a net difference in field strength. When I last checked the ground connector acted as a ground plane and one of the headphone wires served as the actual antenna. It doesn't work that well in practice (in its stock configuration) simply because there's not enough exposed/non-twisted-pair portion of the headphone wire pair to receive a good signal (Only one wire/ground pair acts as the antenna and I can't remember which right now). Once you expose a few inches of the heaphone wire from the ground sheath/pair it works very well as long as you don't go crazy and expose so much antenna that it overloads the RF frontend . > > There are 2 reasons I ask: first, I'd like to be able to do a calibrated > sensitivity check on the FM receiver, which means I need a proper RF > interface to inject the signal from my sig-gen on. Secondly, I work in > what can best be described as RF hell (as you might deduce by the fact > that I have ready access to a calibrated RF sig-gen), and I'd like to be > able to couple my external antenna drop into the N800. I wouldn't do that if I were you. Any time you connect something to you and a external (out-door) antenna you're betting against the possibility of a lightning strike, static discharge, accidentally touching something live and becoming the shortest path to ground, or a host of other unpleasant possibilities. Stick with something cheaper and purpose-built for listening to the radio on; you could even go for one with a remote so you don't have to touch it every time you want to adjust the volume or switch stations. Larry
