Piece of wire antena.

[rainman1]

Hey, i'm looking for some material to read about this issue.
Something thats short and right to the point, just to know how it works.

Thanks.

 

[dknguyen]

LIke how a "dead-end" piece of wire antenna works? You know AC current produces radiates an EM field. A dead-end piece of wire does the same thing in the form of a standing wave inside the piece of wire- the AC current at various points in the wire is different because it takes time for current to travel up and down the wire. The current is not constant along the wire...that's DC or approximated frequency whose wavelength is much longer than the length of the wire. That's why the length is important...you can only fit so many standing waves of a certain frequency in a particular length of wire/antenna. So for the shortest possible effective antenna, you need to fit in enough of a fraction of a wavelength so that the AC current varies by a sufficient amount over the length of the wire. Receiving works the same way.

Personally, I haven't found an article yet. I think that's what someone else said on this forum a while back, and that's as simple as I have been able to find it.

YOu don't need a dead end piece of wire...there are many kinds of antennas and loops of wire that can form a closed circuit are among them. Why dead-end pieces of metal are chosen sometimes...I don't know. Possibly due the distribution pattern of the EM they emit. Maybe someone else does.