Yes, it does help. It helps to disprove that one wave does not push the
preceding wave along. Each is an independent event which does not interact
with other waves from the same source until a boundary or other interface is
encountered, resulting in interference patterns. Then they will affect each
other, both positively and negatively, regarding amplitude.

Snarf


"Crazy George" wrote in message
...
The "pulse" is the envelope of the RF energy. Lots of frequencies more
like
white noise actually, start suddenly, trail off not quite so quickly.
Similar to a radar pulse. Two things. RF, pulse modulated.
Omnidirectionally radiated. Does that help?

--
Crazy George
Remove NO and SPAM from return address
"snarf" wrote in message
...
Without sounding like too much of a wise guy, please explain the single
electromagnetic pulse generated during a nuclear or other type of large
explosion.

Does a certain degree of oscillation (ringing) occur to explain the vast
distances travelled by what one would assume was a single large pulse?

Snarf


"Richard Harrison" wrote in message
...
Nic Santean wrote:
"-from "The Beginners`s Handbook of Amateur Radio" by Clay Laster,
page
260."

Clay used many words to say the signal propagates too far to get back
to
the radiator. It continues its journey away from the radiator.

Radiation is really caused by exchange of energy between alternating
magnetic and electric fields. They produce each other when they
alternate. Static fields don`t radiate. They soon fade away.

J.C. Maxwell speculated that displacement current produces the same
alternating magnetic lines as conduction current does. He was proved
right.

"Static" magnetic and electric fields move out into space when current
flows and charge builds. When they are no longer changing, the fields
at
some distance have reached practical limits and stop expanding.
Alternate these fields, and the fields can build each other and travel
on and on.

Best regards, Richard Harrison, KB5 WZI

Among the numerous effects of a nuclear explosion in the atmosphere are
X-rays and Gamma Rays. These are photons of two greatly different
wavelengths. These photons interact with the atmosphere in a very
complex manner depending on the frequency of the photons. Narratively,
these can be thought of in the following way.

The atmosphere absorbs the photons. The energy in the photons causes
ionization of the air molecules, primarily Nitrogen and Oxygen. The
ionization strips the electrons off of these molecules. This leaves the
nucleus positively charged and creates an electron shower that blasts
away from the nucleus.

So, the electrons, being much lighter than the nucleus, move further
away from the nucleus causing a electromagnetic wave. There is a time
varying electric field between the nucleus and the electrons: and, the
motion of the electrons creates a simultaneous time varying magnetic
field. The electrons 'curve' back to the nucleus to recombine and
produce no net charge in the time period of 10s of microseconds after
the nuclear event.

Now, the X-rays are absorbed by the atmosphere over the distance of
several meters from the blast source. While the Gamma rays are absorbed
over the distance of several kilometers. X-rays and Gamma rays travel at
the speed of light so the resulting waveform of the EM field has a very
fast rise time from the X-rays, a longer rise time for the Gamma rays
and a slower fall time from the Gamma rays.

The EM Pulse has a very fast rise time, typically less than 10
nanoseconds [10 MHz], and a longer fall time typically 10s of
microseconds [ 1 MHz]. A Fourier analysis of the frequency components
shows the EM energy ranges from 100 KHz to in excess of 200 MHz.

So, the resulting EM wave then can propagate in accordance with the
characteristics of the Low Frequency, Medium Frequency, High Frequency
and Very High Frequency propagation characteristics in effect when the
explosion occurs.

Unclassified data indicates the EMP Pulse has field intensities in
excess of 25,000 volts per meter in the HF portion of the spectrum!
[Hmmm ... a ten meter dipole antenna could be in an EM field in excess
of 125,000 volts!! WOW! Talk about ESD susceptibility with the new IC
746 Pro. Not much would survive this unless specifically designed to do so.]

This is a far as I'll go with the explanation.

Deacon Dave, W1MCE

PS: The Rev. Deacon spent many years designing equipment to MIL Specs
including nuclear effects.


[SNIP]
Snarf wrote:
"Without sounding like too much of a wise guy, please explain the single
pulse generated during the single electromagnetic pulse generated during
a nuclear or other type of large explosion."

[SNIP]

Nic. Santean wrote:
I thought that only light (and not radio waves) has a dual nature.
Are U sure that photons play a role in radio waves radiation ??
U sure?

Yep, radio waves and light are the same stuff (photons) just different
frequencies. They are all part of the electromagnetic spectrum that
extends from DC to gamma rays (and higher?)

Using particle physics to explain radiation from an antenna is easier to
understand than fields, waves, and Maxwell's equations. It allows us to
picture a tangible particle leaving the antenna. And lots of things are
understood about photons.

The RF energy from the source accelerates and decelerates free electrons.
The changing energy levels of the free electrons causes the excess energy
to be radiated as coherent photons.
--
73, Cecil, W5DXP

Well, at least one thing you guys succeeded :
made me go to the library and start reading.

An initial feeling I have is that equations and
formulas (Maxwell's and alike) do [describe]
these phenomena; however they do little to
[explain] their very nature. Hence, I guess
pretty soon I will dive into quantum physics
to look for some answers.

For example, I needed the Special Theory of
Relativity to get myself convinced of the intrinsic
reality(!) of the electric/magnetic field. And
this was tough, since is hard to comprehend
some form of physical existence without the
support of matter.

Cordially,

Nic.
http://www.csd.uwo.ca/~nic



"Nic. Santean" wrote in message news:3f16b377@shknews01...

Below is a paragraph - from a known book -
which I have difficulties understanding. Please
somebody explain in more clear terms the
phenomenon.

the context was about dipole antennas,
however the comment has a general nature

"Radiation of electromagnetic waves is created
when the alternating electric and magnetic fields
attempt to collapse back toward the antenna.
However, new fields being created by the next
half cycle push the preceding fields into space,
which is the mechanism of radiation."

- from "The Beginner's Handbook of Amateur
Radio" by Clay Laster, page 260

Cordially,

Nic. Santean
http://www.csd.uwo.ca/~nic/

Now this is what I call a highly detailed answer.
"snarf" wrote in message
.. .
It is incorrect.

Snarf