We have bought a 2nd hand car of Japanese origin, and the stereo unit works through a touch-screen that also controls volume, balance, air-conditioning and just about everything. It has no 3.5mm jack input.
Rather than hack around, I figured I could use a cassette adapter to 3.5mm jack plug for my old iPod Classic. Works a treat. Unfortunately, the FM radio bandwidth in Japan is restricted, so we can only get a couple of a stations here. In our other Japanese imported vehicle, we got round this by sticking a new stereo in.
I have managed to get FM radio by using an old Nokia n900 in place of the iPod, which works, except the reception is poor. I can also use a Samsung Galaxy S3 if need be (would prefer to use the n900, as I use it for nothing else these days). The cable from the cassette adapter is less than a meter, and by the time the FM device is mounted in the holder, there’s probably only a vertical run of under 1/2 a meter.
My understanding is that for decent FM reception, the length needs to be at least a meter (which if inside the windscreen would be horizontal – ideally it should be outside, but that is impractical). I have seen lots of answers that cover extending an aerial on a smartphone by replacing the headphone wire with a telescopic aerial, but that only works for using the internal speaker.
Is there some way of extending the antenna in such a way that you can still use the jack socket to feed the car stereo?
I will get a 3.5mm male to 3.5mm female extension lead for now, but it doesn’t seem very elegant at all, and if I could get this working without it, I could eventually look into utilizing the car’s own built-in aerial antenna at some point.