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Long solenoid with ac.

by sanjibghosh
Tags: solenoid
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Sep1-09, 03:23 PM
P: 50
Recently I found that, if I apply a sinusoidal current to a long solenoid I get a radiation from it. It is completely theoretical result. I want to verify whether my result is correct or not. For this verification I need either some experimental result or some theoretical explanation whether it is wrong or correct,if correct then why this is happening?
please ,please help.
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Bob S
Sep1-09, 03:52 PM
P: 4,663
Here is a paper on loop (solenoid) antennas, including estimate of radiation resistance..
Put a ferrite rod in it and it works better for AM radio (~1 MHz).
Sep5-09, 04:09 AM
P: 50
I got the point and also I found a paper on this topic in American Journal of Physics-1995. One thing I want to know, What the basic difference between the field with radiation and without radiation is.

Sep5-09, 10:00 AM
Sci Advisor
P: 4,044
Long solenoid with ac.

It is also fairly common to use a long piece of tubing and wind a spiral of wire onto it to act as an antenna for vehicle use.
Such antennas resonate at much lower frequencies than the length of the antenna would otherwise allow.

Blank fishing poles made of fibreglass are commonly used and the wire is wound onto the fishing pole with some spacing between turns of wire. It is usually fed from a transmitter via a coaxial cable at the bottom.

These antennas are not very efficient at low frequencies but they do work.

Usually, the resonant frequency has to be found by experimentation but a good start is to wind on about one quarter wave length of wire onto the rod and then mount the rod over a flat metal surface (a ground plane) and test it for resonance and maximum radiation.

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