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Physics

in what form are electric and magnetic fields propagated from an oscillating dipole

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Bill Compton
Bill Compton Answered:

Let us consider the high school level work first and then we will work up to actual physics.

First, let us discuss the basics of Ampere's Law of Magnetic Fields.  Then we will discuss Maxwell's Correection to Ampere's Law.

\oint_{\partial \Sigma} \mathbf{B} \cdot \mathrm{d}\boldsymbol{\ell} = \mu_0 I + \mu_0 \varepsilon_0 \iint_{\Sigma} \frac{\partial \mathbf E}{\partial t} \cdot \mathrm{d}\mathbf{S} \oint_{\partial \Sigma} \mathbf{H} \cdot \mathrm{d}\boldsymbol{\ell} = I_f + \iint_{\Sigma} \frac{\partial \mathbf D}{\partial t} \cdot \mathrm{d}\mathbf{S}

 

We may readily see that the amount of current applied to a winding is not ABSOLUTELY proportional to the field generated: we have impedence and radiative field losses, and we have Maxwell retention in field windings.

Conversely, Maxwell states that we have conservation of energy in that collapsing fields do not collapse instantaneously.  Here we invoke Faraday's First Law, which we will discuss separately.

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Gene Smolin
Gene Smolin Answered:

Look at the second integral.  Basically it says that current applied to an adjoining conductor that also has current will cause both fields to increase by the number of windings in the coil.  Now, let's look at the usual dipole in a 2-meter FM antenna.  We see the Hertz Opposition: the dipoles are each 1/4 wave and then go to 1/16 wave monopoles set 90 degrees from each other.

The lead that meets the transmitting-receiving dipole must be at even wavelengths, meaning we have to mount the mast at 4, 8, 12, 16, or 20 meters and use a "thumb-buster" coil to dial in the exact SWR.

During transmission, the dipole will feel the signal and it will radiate in a torus at 90 degrees from the axis of the dipole, and the monopoles will assure that you do not suffer SSB-backfeed during reception.

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Anonymous
Anonymous Answer:

Leftists are evil. Obatso is a drunk from Kenya. Leftists are racists. Republicans must vote for their own kind. The south will rise again. I pity leftists.

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