Problem in radio circuit

Hi,
I have what most would consider a common problem in a radio circuit. If I touch either the transmitter circuit antenna or the receiver circuit antenna with my hand, the signal strength in my receiver circuit almost doubles. Why does this happen? (I'm using AM by the way, over a 500khz carrier). Does it have anything to do with grounding? How do I avoid it?
Thanks.

niranjay_r said:

Hi,
I have what most would consider a common problem in a radio circuit. If I touch either the transmitter circuit antenna or the receiver circuit antenna with my hand, the signal strength in my receiver circuit almost doubles. Why does this happen? (I'm using AM by the way, over a 500khz carrier). Does it have anything to do with grounding? How do I avoid it?
Thanks.

Click to expand...

Probably just because your body is acting as an aerial. Many, many, years ago (when I was just a lad) a load of us used to meet up the street and listen to the new Top Twenty on Sunday evenings. We soon found that by putting the radio on a wall next to a telegraph pole (with a big cable running down it in to the ground) - the volume improved tremendously, presumably the overhead wires were acting as an aerial and coupling to the sets ferrite rod.

BTW, this was with AM radio as well, Radio One, which used to be on 247m (if I remember correctly).

This always happen if the aerial not tuned, and for 500kHz the 1/8 lambda aerial about 60meters! When You touch the tuned aerial, the signal always decreased.