No, there is no effect of a magnet on RF at the frequencies we use aside from them being a metal object. A permanent magnet is a stationary "field" and it would have to be a moving field to ever be considered. Magnetic latches are common in both transmitters and receivers as part of the interlock protection, ie. they are used on access doors to trigger shutting off power. You can also buy "Mag-mount" antennas for you car when you don't want to drill a hole.
Just one more wire!