Why don't mirrors reflect radio waves?

They do, and you've just never noticed. But if you have a big enough mirror and can point it toward a radio tower, you can test it out yourself. Point this big mirror at the FM radio tower, and get out a portable FM radio. Now start at the mirror and start backing up from the mirror while listening. read more

For mirrors to reflect radio waves you will need to make them thicker as longer the wavelength, to get the same reflectivity you need to increase its thickness. This is the same principle as seeing a light on in your microwave. You can see the light escaping through the door but the microwaves aren't escaping because they're too long. read more

Radio waves almost always travel through space in a straight line. There are two exceptions. One is that radio waves are pulled and turn slightly because of gravity when they pass by large masses. The other exception is that radio waves can be reflected by certain substances, like the way that light is reflected by a mirror. read more

Metallic mirrors will reflect every kind of electromagnetic radiation where the electrical"pixies" in the metal (= electrons) can move around quicker than a certain electrical wave would throw them around (this is called the plasma frequency, the details don't matter). read more

The other exception is that radio waves can be reflected by certain substances, like the way that light is reflected by a mirror. The angle at which a radio wave is reflected from a smooth metal surface (also called the angle of reflectance) is always equal to the angle at which it approached the surface (also called the angle of incidence). read more