How to improve radio receive in my Hyundai Pony?

My 12-year old pony has some problems with the receive of radio signals.
Noise is appearing on normally strong signals, and the area of receive of
signals is definitely smaller than normal.
I suspect the antenna to be the main problem (my old radio had also receive
problems, but with my new radio it even got worse).
Are there some easy ways to improve the antenna. I tried an antenna
amplifier, but the area of receive is not getting larger unfortunately.

Ard.

 

If this car is fuel injected, there should be a noise filter bolted to the
intake plenum with two wires going to it. It's about 2.5cm by 1cm by 1cm.
This could be your problem.

Of course, your problem could also be in your antenna wiring or the new
radio may not receive very well.