I’ve often noticed, when trying to adjust a radio or TV antenna for better reception, that reception improves markedly while I am holding or touching the antenna – and then, maddeningly, goes back to static or snow the moment I let got. Why is this? What is there about the non-metallic human body that should enhance radio or TV reception? And how, if at all, can we exploit this principle to improve reception without holding on to the antenna every second?
The human body does conduct electricity (think salt water), and so it can be a pretty good antenna. Metal is better, and wood or plastic is worse (or no good at all).
Adding a bigger antenna out of any conduction material will make your TV reception better.
I use my body as an antenna when I start my vehicle remotely. What I do is hold the transmitter under my chin when I depress the button - it increases the range of operation considerably.
Not true. The optimum size for an antenna is the typical wavelength it is expected to receive - the the case of TV aerials, about 2ft.
Good point, but isn’t it actually any integral multiple of the wavelength?
I’ve noticed the same thing, but even when I’m not touching the antenna. I used to have an FM transmitter in my car, and the signal would suddenly get better if I put my hand anywhere near the wire.
Or even an integer multiple. 
Mr2001: Air can also conduct electricity, which is why capacitors don’t use air as the dielectric.
The closer to an integral (check your dictionaries) multiple or divisor of the wavelength is best. So 2 and 1/2 wavelength are next best. The difference between 1 and 1/2 wavelength is small enough in most cases that having the shorter antenna makes people happier. But the farther away from 1, the worse it is. (Well, there’s a lot of complications… look, over there, some to distract you!) So having a 4000* wavelength antenna is no good. Also, once you get up to really massive antennas, other losses take over. So that “turn your whole house wiring into an antenna” gimmick is a complete scam.
Also, I have dozens of capacitors in my house that use air! They are called tuning capacitors. Okay, so I’m a bit old timey, but if you have an analog dial radio, that includes you too. Air is considered an insulator for all practical purposes.
I always thought the improved reception had more to do with the body’s extra capacitance than any sort of antenna effect.
Of course they do. Variable capacitors, often used as tuning components in old radio receivers, are air-dielectric capacitors. Air is actually a pretty good insulator at moderate voltages.