[trevor bartram]

My MP3 player has a built in FM radio that works great with my Koss headphones. The headphone lead acts as an antenna. I tried streaming the FM radio to my Blluetooth speaker and that works too. When streaming I'd like to replace the headphones with a telescopic FM antenna. There are several models available at Amazon. I searched here and apparently the headphone ground wire is the antenna. I assume a simple L/C diplexer is used at headphone socket to separate audio return signals and RF signals. I assume the most important aspect of the antenna is that it should have a stereo 3.5mm plug, so as not to short out the L/R audio signals still present at the socket?
Has anyone experience with these telescopic FM antennas terminated with a 3.5mm plug? Those available at Amazon are short (10") whereas ideally they'd be 30+" (similar length to Koss headphone lead).