How come I can always increase the quality of a poor radio signal by grasping the antenna with my hand?

Question

How come I can always increase the quality of a poor radio signal by grasping the antenna with my hand?

Answer 1

Sounds like you're starting with practically no antenna at all.  Your body is becoming part of the antenna, increasing the captured signal strength.  You'll improve it much more by attaching a real antenna.

Answer 2

because of static

it grasps more "energy"

Answer 3

It's body capacitance:

http://en.wikipedia.org/wiki/Body_capaci...

Answer 4

You asked this already...

your body is mostly water, which has a lot of electrolytes like sodium, calcium etc dissolved in it - in solution these ions act as charge carriers. this is why electrical current will flow through your body. the most basic antenna is a piece of wire; this is a piece of metal that has free electrons that move whenever an electric field is nearby. an oscillating electric field, like that in a cellphone signal, will make the electrons in the antenna oscillate, and therefore oscillate in whatever circuit the antenna is attached to.

so, because you're a giant wet conductor, when you are just walking around in the world all of the various kinds of EM radiation around us - TV signals, radio stations, wifi, cell phones.. everything - is making the ions dissolved inside your body oscillate back and forth, as the sum of all of the radiation that passes through you.

when you get near another conductor, even if you're separated by an insulator like the plastic on your antenna, your body capacitively couples to the conductor and effectively increases the area of the antenna. since bigger antennas work better, the signal strength will increase.

you certainly could unscrew the little antenna in your cellphone and attach a giant metal antenna to your cell phone, but then you'd be carrying around a giant cell phone. much of antenna engineering is about trading off size (for portability or aesthetic or whatever reasons) vs. how well it picks signals up.