http://www.aftenposten.no/english/lo...ticleID=609108

not much info there,

Here's some more info: http://www.ancom.no/presentation01.htm

I saw it on Norwegian TV a week or two ago, and it sounded impressive to me.

Sverre
www.qsl.net/la3za

In article t,
Active8 wrote:

In article ,
says...
http://www.aftenposten.no/english/lo...ticleID=609108

I've always assumed that the performance of ferrite-rod antennas in
transmitting applications was limited by core saturation. Wonder if
there's anything to this "invention"?

-- jm

------------------------------------------------------
http://www.qsl.net/ke5fx
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------

not much info there, but i've read articles about russian experiments on
small antennae and something about a capacitive antenna.

somewhere in the jumble, i came across a theory/claim supposedly
originated by Nikolai Tesla. the theory being that applying a large
voltage - low freq. ac, dc... i don't remember - to a short antenna
would set up an electrically large antenna by virtue of the electric
field.

say you applied 1000V to a 1m whip. that's 1000V/m. or it's 1V/m over a
length of 1000m effective antenna length. that's the theory... key word
"theory".


You're misusing the word "theory." You mean hypothesis. I know, I know,
I'm nitpicking. But I once was chewed out by a physicist at MIT for
misusing the word when I was temping there. Ouch.

Al

PS:

theory - a proven fact which explains an aspect of nature; i.e., the
Theory of Relativity.

hypotheses - A tentative explanation that accounts for a set of facts
and must be proven by further experimentation.

--
There's never enough time to do it right the first time.......

On Wed, 17 Sep 2003 05:10:40 GMT, Active8
wrote:

In article ,
says...
http://www.aftenposten.no/english/lo...ticleID=609108


Hmmm... sounds bogus to me.

somewhere in the jumble, i came across a theory/claim supposedly
originated by Nikolai Tesla. the theory being that applying a large
voltage - low freq. ac, dc... i don't remember - to a short antenna
would set up an electrically large antenna by virtue of the electric
field.

say you applied 1000V to a 1m whip. that's 1000V/m. or it's 1V/m over a
length of 1000m effective antenna length. that's the theory... key word
"theory".

An antenna has radiation resistance. If you deliver power into Rr, it,
well, radiates it. As an antenna gets smaller, its radiation
resistance increases, so to dump X watts into space using a smaller
antenna, you need to drive it from a higher voltage. P = E^2/Rr. One
gadget used to increase the voltage is an "antenna tuner", just a
resonant matching network. There are practical limits on how much
power you can force into a small antenna: skin effect heating,
ionization, matching network Q, stuff like that. Nothing mysterious
here.

John





brs,
mike

Well, actually, no. The radiation resistance generally decreases as an
antenna gets smaller, assuming it's small compared to a wavelength.

Roy Lewallen, W7EL

John Larkin wrote:

An antenna has radiation resistance. If you deliver power into Rr, it,
well, radiates it. As an antenna gets smaller, its radiation
resistance increases, so to dump X watts into space using a smaller
antenna, you need to drive it from a higher voltage. P = E^2/Rr. One
gadget used to increase the voltage is an "antenna tuner", just a
resonant matching network. There are practical limits on how much
power you can force into a small antenna: skin effect heating,
ionization, matching network Q, stuff like that. Nothing mysterious
here.

John

On Wed, 17 Sep 2003 15:41:33 -0700, Roy Lewallen
wrote:

Well, actually, no. The radiation resistance generally decreases as an
antenna gets smaller, assuming it's small compared to a wavelength.

Roy Lewallen, W7EL


At any given frequency, you can analyze the impedance of a small
antanna as a series R-C or a shunt R-C. Viewed as a shunt resistance,
Rr increases as the antenna gets smaller, and as a series network, it
gets smaller.

I guess the standard convention must be to treat Rr as a series
element, so it gets smaller as the antenna gets smaller.

Either way, it takes more volts (or, if you prefer, more amps) to
force a small antenna to radiate as much as a larger one.

John

Yes, "resistance" is traditionally used to mean the real part of an
impedance, which in turn is expressed as a complex number. An equivalent
circuit for an impedance is then a series R - X, with the R and X
corresponding to the real and imaginary parts of the impedance
respectively. Parallel equivalents are of course also used, but usually
explicitly described as a parallel equivalent, or given as a complex
admittance (G + jB, with G and B representing the shunt conductance and
susceptance).

As an antenna gets smaller, the impedance does rise, causing a
requirement for more voltage for a given power. The rise, however, is
due to increasing (series) reactance, not radiation resistance. If you
make the antenna long enough to reach resonance, then continue making it
longer, the impedance again rises until you hit "anti-resonance"
(parallel resonance). In that region it's due to both an increasing
reactance and an increasing radiation resistance.

A real consequence of the low radiation resistance of a small antenna is
that the conductor current is very high for a given applied power. This
results in increased I^2 * R loss in the conductors. The loss can be
very substantial in small antennas.

Roy Lewallen, W7EL

John Larkin wrote:
On Wed, 17 Sep 2003 15:41:33 -0700, Roy Lewallen
wrote:


Well, actually, no. The radiation resistance generally decreases as an
antenna gets smaller, assuming it's small compared to a wavelength.

Roy Lewallen, W7EL



At any given frequency, you can analyze the impedance of a small
antanna as a series R-C or a shunt R-C. Viewed as a shunt resistance,
Rr increases as the antenna gets smaller, and as a series network, it
gets smaller.

I guess the standard convention must be to treat Rr as a series
element, so it gets smaller as the antenna gets smaller.

Either way, it takes more volts (or, if you prefer, more amps) to
force a small antenna to radiate as much as a larger one.

John

Yes, "resistance" is traditionally used to mean the real part of an
impedance, which in turn is expressed as a complex number. An equivalent
circuit for an impedance is then a series R - X, with the R and X
corresponding to the real and imaginary parts of the impedance
respectively. Parallel equivalents are of course also used, but usually
explicitly described as a parallel equivalent, or given as a complex
admittance (G + jB, with G and B representing the shunt conductance and
susceptance).

As an antenna gets smaller, the impedance does rise, causing a
requirement for more voltage for a given power. The rise, however, is
due to increasing (series) reactance, not radiation resistance. If you
make the antenna long enough to reach resonance, then continue making it
longer, the impedance again rises until you hit "anti-resonance"
(parallel resonance). In that region it's due to both an increasing
reactance and an increasing radiation resistance.

A real consequence of the low radiation resistance of a small antenna is
that the conductor current is very high for a given applied power. This
results in increased I^2 * R loss in the conductors. The loss can be
very substantial in small antennas.

Roy Lewallen, W7EL

John Larkin wrote:
On Wed, 17 Sep 2003 15:41:33 -0700, Roy Lewallen
wrote:


Well, actually, no. The radiation resistance generally decreases as an
antenna gets smaller, assuming it's small compared to a wavelength.

Roy Lewallen, W7EL



At any given frequency, you can analyze the impedance of a small
antanna as a series R-C or a shunt R-C. Viewed as a shunt resistance,
Rr increases as the antenna gets smaller, and as a series network, it
gets smaller.

I guess the standard convention must be to treat Rr as a series
element, so it gets smaller as the antenna gets smaller.

Either way, it takes more volts (or, if you prefer, more amps) to
force a small antenna to radiate as much as a larger one.

John

On Wed, 17 Sep 2003 15:41:33 -0700, Roy Lewallen
wrote:

Well, actually, no. The radiation resistance generally decreases as an
antenna gets smaller, assuming it's small compared to a wavelength.

Roy Lewallen, W7EL


At any given frequency, you can analyze the impedance of a small
antanna as a series R-C or a shunt R-C. Viewed as a shunt resistance,
Rr increases as the antenna gets smaller, and as a series network, it
gets smaller.

I guess the standard convention must be to treat Rr as a series
element, so it gets smaller as the antenna gets smaller.

Either way, it takes more volts (or, if you prefer, more amps) to
force a small antenna to radiate as much as a larger one.

John

Well, actually, no. The radiation resistance generally decreases as an
antenna gets smaller, assuming it's small compared to a wavelength.

Roy Lewallen, W7EL

John Larkin wrote:

An antenna has radiation resistance. If you deliver power into Rr, it,
well, radiates it. As an antenna gets smaller, its radiation
resistance increases, so to dump X watts into space using a smaller
antenna, you need to drive it from a higher voltage. P = E^2/Rr. One
gadget used to increase the voltage is an "antenna tuner", just a
resonant matching network. There are practical limits on how much
power you can force into a small antenna: skin effect heating,
ionization, matching network Q, stuff like that. Nothing mysterious
here.

John

On Wed, 17 Sep 2003 05:10:40 GMT, Active8
wrote:

In article ,
says...
http://www.aftenposten.no/english/lo...ticleID=609108


Hmmm... sounds bogus to me.

somewhere in the jumble, i came across a theory/claim supposedly
originated by Nikolai Tesla. the theory being that applying a large
voltage - low freq. ac, dc... i don't remember - to a short antenna
would set up an electrically large antenna by virtue of the electric
field.

say you applied 1000V to a 1m whip. that's 1000V/m. or it's 1V/m over a
length of 1000m effective antenna length. that's the theory... key word
"theory".

An antenna has radiation resistance. If you deliver power into Rr, it,
well, radiates it. As an antenna gets smaller, its radiation
resistance increases, so to dump X watts into space using a smaller
antenna, you need to drive it from a higher voltage. P = E^2/Rr. One
gadget used to increase the voltage is an "antenna tuner", just a
resonant matching network. There are practical limits on how much
power you can force into a small antenna: skin effect heating,
ionization, matching network Q, stuff like that. Nothing mysterious
here.

John





brs,
mike