I bought a device from Rat Shack (can be also found on the I'Net) that permits a user to listen to an Ipod via a selected FM frequency on the car's radio. However, noise encountered by traffic light controllers, high tension lines, etc., is really annoying.
I finally found a solution to the problem! I hope this idea is usable by others.
I bought some 24 gauge copper wire and wrapped it around the lead from the freq selector to the cig lighter, then ran that wire (actually an antenna now) under the carpeting and back seat. This then actually fills the car with the signal and the radio's antenna in the rear window isn't as sensitive to the interfering outside electrical noise.
In my case the interior is black so I found some *black* 24 gauge wire at a hobby store for $2.98, it's used by people making jewelery, etc.
PS. No, you won't lose your hair or become sterile from that FM signal. ;-)