"Roy Lewallen" wrote

Hm. Have my postings gone unread? Or just unbelieved?

==================================

Or, am I trying to find somebody else who believes you ?

Terman, Kraus and Balanis and some computer programs are of no help!
;o)
----
Reg.

Reg, G4FGQ wrote:
"Terman, Kraus, and Balanis and some computer programs are of no help!"

My dictionary defines "field strength" as:
"3. The strength of radio waves at a distance from the transmitting
antenna, usually expressed in microvolts-per-meter. This is not the same
as the strength of a radio signal at the antenna terminals of the
receiver."

The definition looks OK to me. The reason the signal is not the same as
the microvolts-per-meter even when the antenna is a 1-meter length of
wire with just the right slant is because the induced voltage gets
divided between the antenna and its load (the receiver).

Maybe Cecil`s IEEE dictionary has something to say about field strength.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:
Maybe Cecil`s IEEE dictionary has something to say about field strength.

magnitude of the electric field vector in volts per meter, or
magnitude of the magnetic field vector in amps (or ampere-turns) per meter,
or power flux density P in watts per square meter.
--
73, Cecil http://www.qsl.net/w5dxp

Richard Harrison wrote:
Reg, G4FGQ wrote:
"Terman, Kraus, and Balanis and some computer programs are of no help!"

My dictionary defines "field strength" as:
"3. The strength of radio waves at a distance from the transmitting
antenna, usually expressed in microvolts-per-meter. This is not the same
as the strength of a radio signal at the antenna terminals of the
receiver."

The definition looks OK to me. The reason the signal is not the same as
the microvolts-per-meter even when the antenna is a 1-meter length of
wire with just the right slant is because the induced voltage gets
divided between the antenna and its load (the receiver).


No, that's not why. The terminal voltage of an open circuited 1 meter
(electrically short) dipole is 1/2 the field strength in volts/meter.
The terminal voltage when terminated with a conjugately matched load can
be well over a thousand volts (in the theoretical lossless case).

But it's pointless to keep repeating this. Reg keeps asking the same
question, and you keep responding with the same incorrect answers. I
believe I've gotten through to everyone who really wants to know the
answers, so I'll let this be my last repetition.

Roy Lewallen, W7EL

"Richard Harrison" bravely wrote to "All" (20 Dec 05 09:38:02)
--- on the heady topic of " Antenna reception theory"

RH From: (Richard Harrison)
RH Xref: core-easynews rec.radio.amateur.antenna:221565

RH Reg, G4FGQ wrote:
RH "Terman, Kraus, and Balanis and some computer programs are of no
RH help!"
RH My dictionary defines "field strength" as:
RH "3. The strength of radio waves at a distance from the transmitting
RH antenna, usually expressed in microvolts-per-meter. This is not the
RH same as the strength of a radio signal at the antenna terminals of the
RH receiver."

RH The definition looks OK to me. The reason the signal is not the same
RH as the microvolts-per-meter even when the antenna is a 1-meter length
RH of wire with just the right slant is because the induced voltage gets
RH divided between the antenna and its load (the receiver).


Not only that, but also this: the antenna rebroadcasts half of the
intercepted energy.

A*s*i*m*o*v

Asimov wrote:
. . .
RH The definition looks OK to me. The reason the signal is not the same
RH as the microvolts-per-meter even when the antenna is a 1-meter length
RH of wire with just the right slant is because the induced voltage gets
RH divided between the antenna and its load (the receiver).


Not only that, but also this: the antenna rebroadcasts half of the
intercepted energy.

But voltage isn't energy. Or power.

Roy Lewallen, W7EL

Roy Lewallen wrote:
But voltage isn't energy. Or power.

True, but voltage cannot exist without energy.
--
73, Cecil http://www.qsl.net/w5dxp

Be carefully, that is not exactly true. Voltage cannot be created without
energy, it is a force. However once it is 'in place' it requires no energy to
sustain. (Given the freshman physics caveats of frictionless pullies, massless
ropes, etc.)

That said in the situation at hand of an AC voltage being induced by an EM field
you are correct. The energy required to produce a voltage is a function of the
impedance.

- Dan

Cecil Moore wrote:
Roy Lewallen wrote:

But voltage isn't energy. Or power.


True, but voltage cannot exist without energy.

dansawyeror wrote:
Be carefully, that is not exactly true. Voltage cannot be created
without energy, it is a force.

Dan,

Stop now, before you further embarrass yourself.

73,
Gene
W4SZ

dansawyeror wrote:
Be careful, that is not exactly true. Voltage cannot be created
without energy, it is a force. However once it is 'in place' it requires
no energy to sustain.

A voltage cannot be sustained without energy. The
joule of energy used to create a voltage on a capacitor
is stored in the capacitor until something changes.
--
73, Cecil http://www.qsl.net/w5dxp