If my antenna is connected to ground through a 50 Ohm resistor, or smaller, it's okay for reception still?
2007-08-23 21:01:27 · 4 answers · asked by rusty 3 in Science & Mathematics ➔ Engineering
Antennas work on the principle that there exists a radiating or active element and a ground.
Look at a tv antenna. there are actually two 'elements' one side is the ground and the other is the 'hot' side. this is called a dipole antenna and it is a balanced antenna. (electically not physically balanced).
I assume that you are trying to ground your antenna. ground it with bare copper wire attached to the 'ground' side of the antenna of course. If you ground the 'hot' side all of the signals will go to ground and you will hear nothing.
Few people understand the 'ground' concept well so I'll elaborate a little more on it here.
Grounds are sometimes called a counterpoise. Since radio frequencies are x mitted using AC voltages the current in the antenna moves back and forth along the length of the wire. When this voltage goes positive on the 'hot side' or 'driven element' it must come from somewhere else. Usually the shorter the wire connecting the antenna to ground the better. Otherwise it will become 'resonant' and also try to act like an antenna also especially if its round wire. This is why copper straps are often used for good RF grounds.
Another example is a CB antenna on a car. The one wire you see is the hot side or driven element while the metal body of the car makes up the ground or counterpoise since the car has rubber tires and is thus insulated from the 'ground'.
Basically the hot side needs to be isolated and the ground seperate. Antennas that are well grounded dissipate excess electrical charge to the ground reducing the potential voltage differnce build up thus reducing lightning strikes.
2007-08-24 06:57:49 · answer #1 · answered by D 3 · 0⤊ 0⤋
Lightning strikes the lowest resistance path to ground.
I have seen it miss the house to strike the well casing.
That 50 Ohm resistor will isolate your signal from ground, but not lightning.
2007-08-24 04:45:15 · answer #2 · answered by Irv S 7 · 2⤊ 0⤋
Lightning strikes wherever the hell it damn well pleases.
2007-08-24 04:10:01 · answer #3 · answered by Anonymous · 0⤊ 0⤋
trees don't stand by one.
2007-08-24 04:06:52 · answer #4 · answered by Christie W 4 · 0⤊ 0⤋