how come when the radio is on and i change positions in my chair, it gets static-y?

Question

just wondering..

Answer 1

I suspect you are talking FM radio and not AM.

The wavelength on FM is fairly short (less than 5 meters) and signals can be reflected from your body. Should the signal of the station be reflected from you to the antenna, the two signals can either be in phase (enhanced) or out of phase (canceled - at least partially). All you need is to change the position of your body a maximum of a couple of meters in the wrong direction .... and often much less. On a car radio receiving broadcast FM stations, you can sometimes hear what is described as "picket fencing" as the signal flutters in and out due to the motion of your vehicle. Again, this is most pronounced on non-local stations.

As you move about, the signal strength of the desired station changes quite a bit. Should it get low enough, your radio is no longer at full quieting and you notice it as static. This can also happen with over the air analog television stations - especially if you don't have a decent antenna on the television. Of course, most of us are on cable or satellite, but should you have rabbit ears still, I'm sure you've noticed the problem - especially on weaker signals (such as out of town, slightly snowy signals). Moving about can result in a better picture or no picture at all.

Hope this helps ;)


Best regards,
Jim

Answer 2

In plain English, your body will often act as an antenna. If you've ever noticed how you get a station tuned just right and then you let go or move away from the radio, it gets, as you describe, static-y? That's why - your body had been enhancing the radio's internal or external antenna and when you moved, it goes Kablooey. I sometimes prefer Kablooey to static-y, though either will work (these are VERY technical terms after all ;<)

Good Luck and Good Listening
-a guy named duh

Answer 3

Your body is acting as an antenna which is picking-up EMI (electro-magnetic interference).
EMI is generated by sources such as florescent lamps, thunderstorms, electric motors and automotive ignition systems.

The space between your body and the radio's antenna acts as a capacitor which capacitively couples this interference into the radio.

Answer 4

Congratulations! You're a human antennae.

Answer 5

it's all about you
or
you have a cheap radio