Antenna reception theory
 

Cecil Moore wrote:
Roy Lewallen wrote:

But some people just can't deal with any idea they didn't come up with
on their own ...


You mean like Ptotal = P1 + P2 + 2*SQRT(P1*P2)cos(a) ? :-)
The first time I saw that equation was in Dr. Best's QEX article.

Yes, and you didn't believe it when you saw it.
73,
Tom Donaly, KA6RUH

Antenna reception theory
 

Tom Donaly wrote:
Cecil Moore wrote:
You mean like Ptotal = P1 + P2 + 2*SQRT(P1*P2)cos(a) ? :-)
The first time I saw that equation was in Dr. Best's QEX article.

Yes, and you didn't believe it when you saw it.

Your memory is slightly faulty. What I objected to was Dr. Best's
assertion that 75w + 8.33w = 133.33w. It still doesn't, never did,
never will, and violates the conservation of energy principle.
What Dr. Best apparently failed to realize is that the extra 50
watts of energy required to balance that energy equation does
NOT come from waves P1 and P2 but instead comes from wave
cancellation of waves P3 and P4 on the source side of the match
point. Wave P1 contains 75 watts and Wave P2 contains 8.33 watts.
Without a source of constructive interference energy, they cannot
add up to 133.33 watts. That source is destructive interference
energy, -2*SQRT(P3*P4), from the source side of the match point
which supplies the +2*SQRT(P1*P2) constructive interference energy
to the load side of the match point where (P1*P2)=(P3*P4). At an
impedance discontinuity in a transmission line, far away from any
source, all constructive interference energy must necessarily be
balanced by an equal magnitude of destructive interference energy
in order to satisfy the conservation of energy principle.

This is all explained in my "WorldRadio", Oct./Dec. 2005 articles.
Unfortunately, most of the Greek letter Thetas didn't make it
through the conversion process and wound up as underline marks.
Part I is already on my web page under "The Rest of the Story"
along with a couple of remarks about forward power, reflected power,
superposition, and interference. Part II will appear on my web page
after Christmas.
--
73, Cecil http://www.qsl.net/w5dxp

Antenna reception theory
 

Asimov wrote:
"An antenna is just a stationary probe in a moving E-field."

Along some path in space there is an electric current which is changing.
It is growing or it is shrinking. It is not constant..

This current as a result of its changes radiates electric and magnetic
flux. The electric flux lines are are perpendicular to the current path.
The magnetic flux lines encircle the current path. The flux is moving
away from the current path at the speed of light. At a distant point
these electric and magnetic flux lines arrive because they sustain each
other during their long trip.

There is an initial wavefront. It started as a spherical wavefront but
has traveled so far that for practical purposes it is now a plane wave.
In the wavefront there is an electric force which would attract or repel
electrons but it has the same strength everywhere over the arriving
wavefront. Therefore, wlectrons in a wire parallel to the wavefront are
not moved along its length by the electric force. This force would only
tend to move electrons from one side of the wire`s diameter to the other
side of the same diameter. Our interest is in current along the length
of the wire.

However, the magnetic lines of force are sweping at the speed of light
across the wire which parallels the wavefront. If the wire also
parallels the direction of the current which generated the lux (is
correctly polarized), it will experience a voltage induced all along its
length. This induction is totally a result of the magnetic field.

Best regards, Richard Harrison, KB5WZI

Antenna reception theory
 

There are some serious errors in this explanation.

1. The source is not an "electric current which is changing". There is an EM
field made up of photons. There are two theories describing this, one is a wave
theory and the other is a particle theory. Neither one completely enplains the
phenomenon.

2. There is no current and therefore there is no "current path".

3. The E and H aspects behave similarly, both are changing. The E domain is no
different in that respect then the H domain. The E portion of this particle/wave
phenomenon is as capable of transforming into a useful signal in the antenna
the H portion is.

Antennas can be either E devices or H devices. E devices respond to the electric
dimension and create a signal while H devices respond to the magnetic dimension
and create a signal.

Dan

Richard Harrison wrote:
Asimov wrote:
"An antenna is just a stationary probe in a moving E-field."

Along some path in space there is an electric current which is changing.
It is growing or it is shrinking. It is not constant..

This current as a result of its changes radiates electric and magnetic
flux. The electric flux lines are are perpendicular to the current path.
The magnetic flux lines encircle the current path. The flux is moving
away from the current path at the speed of light. At a distant point
these electric and magnetic flux lines arrive because they sustain each
other during their long trip.

There is an initial wavefront. It started as a spherical wavefront but
has traveled so far that for practical purposes it is now a plane wave.
In the wavefront there is an electric force which would attract or repel
electrons but it has the same strength everywhere over the arriving
wavefront. Therefore, wlectrons in a wire parallel to the wavefront are
not moved along its length by the electric force. This force would only
tend to move electrons from one side of the wire`s diameter to the other
side of the same diameter. Our interest is in current along the length
of the wire.

However, the magnetic lines of force are sweping at the speed of light
across the wire which parallels the wavefront. If the wire also
parallels the direction of the current which generated the lux (is
correctly polarized), it will experience a voltage induced all along its
length. This induction is totally a result of the magnetic field.

Best regards, Richard Harrison, KB5WZI

Antenna reception theory
 

On Mon, 05 Dec 2005 07:05:09 -0800, dansawyeror
wrote:

Antennas can be either E devices or H devices.

Hi Dan,

Only at D.C. and then it mocks the sense of what an antenna should be.

73's
Richard Clark, KB7QHC

Antenna reception theory
 

"Richard Harrison" bravely wrote to "All" (05 Dec 05 08:08:30)
--- on the heady topic of " Antenna reception theory"

RH From: (Richard Harrison)
RH Xref: core-easynews rec.radio.amateur.antenna:220833
[,,,]
RH There is an initial wavefront. It started as a spherical wavefront but
RH has traveled so far that for practical purposes it is now a plane
RH wave. In the wavefront there is an electric force which would attract
RH or repel electrons but it has the same strength everywhere over the
RH arriving wavefront. Therefore, wlectrons in a wire parallel to the
RH wavefront are not moved along its length by the electric force. This
RH force would only tend to move electrons from one side of the wire`s
RH diameter to the other side of the same diameter. Our interest is in
RH current along the length of the wire.
[,,,]

There is a time varying voltage gradient in the E field too. Turn the
wire around 90" then to find the E gradient. If the wire length is
such that one end is positive while the other end is negative then
charges will flow inbetween both ends.

Anti-static spray won't work on an antenna.

A*s*i*m*o*v

.... My wife and I always hold hands. If I let go, she shops.

Antenna reception theory
 

Cecil Moore wrote:
Tom Donaly wrote:

Cecil Moore wrote:

You mean like Ptotal = P1 + P2 + 2*SQRT(P1*P2)cos(a) ? :-)
The first time I saw that equation was in Dr. Best's QEX article.


Yes, and you didn't believe it when you saw it.

Wave P1 contains 75 watts and Wave P2 contains 8.33 watts.
Without a source of constructive interference energy, they cannot
add up to 133.33 watts.

And obviously he still doesn't believe it, Gene.

73, ac6xg

Antenna reception theory
 

Jim Kelley wrote:
Wave P1 contains 75 watts and Wave P2 contains 8.33 watts.
Without a source of constructive interference energy, they cannot
add up to 133.33 watts.

And obviously he still doesn't believe it, Gene.

Without the 2*SQRT(P1*P2)=50w constructive interference energy,
75w + 8.33w will *NEVER* add up to 133.33 watts. Dr. Best's
equation, 75w + 8.33w = 133.33w, is superposition of powers
which is not allowed AND a violation of the conservation of
energy principle. You don't really support superposition of
powers and violations of conservation of energy, do you?.

If you furnish exactly 75 watts and your neighbor furnishes
exactly 8.33 watts, can you power a 133.33 watt device?
--
73, Cecil http://www.qsl.net/w5dxp

Antenna reception theory
 

Gene, W4SZ wrote:
"Terman`s comment on page 2 of the 1955 edition simply points out the
operation of Faraday`s Law."

Faraday`s law says that, while the magnetic flux linked with a closed
path loop or coil is changing, the closed path is the source of an
electromotive force (voltage) whose magnitude depends only upon the rate
of change of the flux through the path.

If we cause an antenna to be surrounded by an altrernating magnetic
field, a voltage will be induced in the antenna in accordance with
Faraday`s law, This induced voltage is necessary and sufficient to
account for all of the energy received by the antenna.

Best regards, Richard Harrison, KB5WZI

Antenna reception theory
 

Hi Jim,

I was going to try to stay out of this recurring silliness, but since
you accidentally pulled me in I will add my spin.

The only mistake made by Steve Best was allowing himself to get dragged
by Cecil into the intellectual landfill. Yes, most people with
rudimentary arithmetic skills would agree that 75 plus 8.33 does not
equal 133.33.

However, anyone even remotely familiar with waves would readily
understand that the component waves Cecil loves to talk about are merely
mathematical conveniences. It is entire possible to set up other model
configurations, such as a combination of a one traveling wave and one
standing wave.

In order to make his model work, Cecil needs to invoke the mythical P3
and P4 on the source side of the reflection discontinuity. He never gets
around to explaining how these two waves, which exactly cancel at all
points in space and at all times, can contain any energy at all.

The reason that most practitioners of wave models solve for the fields
first and then worry about power or energy is:

a - This procedure works correctly all the time.

b - It avoids the problems created by analyzing fictitious extra
components added for mathematical convenience but containing no physical
reality.

I do not expect to change Cecil's mind. Other than his own potential
embarrassment from the silly publications in World Radio, his folly is
harmless.

73,
Gene
W4SZ

Jim Kelley wrote:


Cecil Moore wrote:

Tom Donaly wrote:

Cecil Moore wrote:

You mean like Ptotal = P1 + P2 + 2*SQRT(P1*P2)cos(a) ? :-)
The first time I saw that equation was in Dr. Best's QEX article.



Yes, and you didn't believe it when you saw it.


Wave P1 contains 75 watts and Wave P2 contains 8.33 watts.
Without a source of constructive interference energy, they cannot
add up to 133.33 watts.


And obviously he still doesn't believe it, Gene.

73, ac6xg