I have realized that my RDX antenna has mediocre FM reception. It has probably weaker reception than in all of my previous cars.
I live in Los Angeles, so it's all flatlands. Yet some stations have static/noise. I have also realized that when I unscrew the antenna to take the car through the car wash, my FM reception gets only marginaly worse.
Thus, I believe that there might be something wrong with the antenna.
Has anyone else felt the same?
How can I check if my antenna is good?
My AM/XM reception is good.

 

Go to the dealership and test out another RDX. Try to be as close to your RDX and ask the salesman for a key to test out the sound. Listen to both RDXS' at the same radio station.

That's my guess to easily figuring things out.

 

I had an 2005 MDX with the base model stereo. I had a lot of AM/FM reception issues. Also my XM sounded like it was playing in a tin can. I now have a 2008 RDX with Tech Package. I am much more pleased with the reception on both however the XM still sounds not as good as FM or CD or AUX.

It might not be a problem with your antenna but where you live. I notice in areas of South Florida there are a lot of pirated radio stations that only transmit for a few miles. When I am in an area with these stations the radio does get static and bleed over from the illegal radio stations. I am sure L.A. has the same problem. Cell phone towers, emergency radio bands (fire, EMS, Police), electric lines, etc.. can also interfere.

At one time I was thinking of having a FM booster installed. Don't know if it would have worked.

I hope this helped a little.