A 2 part question about aluminum foil and radio waves?

1. Does putting aluminum foil on a small radio antenna, boost the signal. So you can pick up radio stations better.
2. Or does aluminum foil block all signals, frequencies, or radio waves in the radio spectrum?

The simple answer is "try it and see if it helps"

The longer is answer is;

I've tried it with limited success. No good for AM; you should move the whole radio. For FM it works sometimes. The only way I've seen any benefit is by attaching foil to a FM antenna with the ends stripped away connecting the foil to bare wires.

But my positive results could have been simply the result of using a corded FM antenna vs. the on-board telescopic one.

But really, how much is foil and how hard is it to experiment yourself?

Good luck and happy receiving.