In article ,
Roy Lewallen wrote:

Reg Edwards wrote:

No he didn't. 7dB, about one S-unit, is not enough to come to anybody's
attention. . .

Yet look at all the people who go to all the trouble of putting up a 3
element beam, then think that the 7 dB gain over a dipole actually makes
their signal louder. Or get a 500 watt amplifier for their 100 watt rig.
Silly fools! Old wives!

Roy Lewallen, W7EL

back on topic,..

i still ponder if i put power into a superconducting antenna if their
is no resistance, and a given about of power would therefore 'stay' in
the antanna longer ie no resistance and a sorta flywheel effect exists
the fields would have to exist longer for fixed-given power , ..

seems that all adds up to more than a trival gain

looks like ill have to use some cheep material like copper or something
elese i can make superconduct unless i can use a supension of
conductive materials into a coolent itself an make a tube that will
radiate while being superconductive just cause i wonder if that will
work as good as a stp based liquid antenna

who knows maybe i'll stumble over 3xtra db

will the antenna stay resonant as it nears criticaltemp? and reaches it?

back on topic,..

i still ponder if i put power into a superconducting antenna if their
is no resistance, and a given about of power would therefore 'stay' in
the antanna longer ie no resistance and a sorta flywheel effect exists
the fields would have to exist longer for fixed-given power , ..

seems that all adds up to more than a trival gain

Not really, no, at least not in the commoner cases.

Let's assume that you could find a superconductor which would be
truly superconducting even at RF frequencies (which today's
superconductors are not, I gather). So, you could cut the loss
resistance of the antenna to precisely zero, in this hypothetical
case.

According to a note Reg posted some time ago, "At 3.75 MHz the
resistance of 20 awg copper wire is 0.206 ohms per metre. Overall
end-to-end dipole resistance 8.24 ohms."

Using the hypothetical perfect superconductor (which may be
impossible) you might reduce this dipole resistance to zero. Great
reduction in loss, right?

Less than you'd think. Remember, the loss resistance of 8.24 ohms
appears in series with the antenna's radiation resistance (which is
due to the RF energy being radiated) which will be around 70 ohms for
an antenna in free space. With the loss resistance present, just
under 90% of the energy is radiated ("dissipated" in the "radiation
resistance"), and 10% turns into heat in the loss resistance.

Getting rid of the loss resistance entirely will thus increase your
radiated power by only about 10% - a small fraction of one dB.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

The fact that superconductors have zero resistance above DC isn't a
limitation of today's technology (although technology limitations cause
current high-temperature superconductors to have resistivity greater
than theoretically possible), but a fundamental property of the nature
of superconductors.

What I'm saying is that a "truly superconducting", "hypothetical
perfect" superconductor has finite resistance at any frequeny above DC.
Imagining a material that has zero resistivity at frequencies above DC
requires imagining something other than a superconductor.

Roy Lewallen, w7EL

Dave Platt wrote:
. . .
Let's assume that you could find a superconductor which would be
truly superconducting even at RF frequencies (which today's
superconductors are not, I gather). So, you could cut the loss
resistance of the antenna to precisely zero, in this hypothetical
case.

. . .
Using the hypothetical perfect superconductor (which may be
impossible) you might reduce this dipole resistance to zero. Great
reduction in loss, right?
. . .

In article ,
Roy Lewallen wrote:

The fact that superconductors have zero resistance above DC isn't a
limitation of today's technology (although technology limitations cause
current high-temperature superconductors to have resistivity greater
than theoretically possible), but a fundamental property of the nature
of superconductors.

What I'm saying is that a "truly superconducting", "hypothetical
perfect" superconductor has finite resistance at any frequeny above DC.
Imagining a material that has zero resistivity at frequencies above DC
requires imagining something other than a superconductor.

Roy Lewallen, w7EL

Dave Platt wrote:
. . .
Let's assume that you could find a superconductor which would be
truly superconducting even at RF frequencies (which today's
superconductors are not, I gather). So, you could cut the loss
resistance of the antenna to precisely zero, in this hypothetical
case.

. . .
Using the hypothetical perfect superconductor (which may be
impossible) you might reduce this dipole resistance to zero. Great
reduction in loss, right?
. . .

well seems everyone is 'strictly' (narrow) focused on the antenna's
resistence loss, i mentined it as the starting point as that is first
thing i think of when it goes critical... however one the resistance
drops, other effects take place no? both in the material and in respect
to other forces aside from just resistance, once it reaches near 0 and
begins being a superconductor

guess i won't know until i build it and mesure it i wanted to try 10m
really but 2m might be easier to keep chilly(0) and i am looking
foward to rig it i've got most of the stuff i think i need so far

i'd also like to build a superconductie ocilator, i'd suspect that i
could power it using a truly small ammount of power?

I would like to put a different spin on the 7dB statement below.

Where the extra gain or power really comes into play is very weak signal
DXing - not the pileups necessarily.

Cases in point - my Dxing log has several contacts where using a linear got
my signal far enough above the noise level for the DX station to understand
me. True on phone or CW. In most of these cases, the DX was calling QRZ and
no one was answering -- the DX station was so weak -- seems folks just gave
up or maybe everyone worked them. Turning on the linear got me the
contacts. Definitely Without Question - Worked an R1MV Malyj Vysotskij, HK0
Malpelo Is, VK9/M Mellish Reef, and VP8/G So Georgia by turning on the
linear feeding a vertical multibander.

I had this happen enough times to realize this to be the real benefit of
adding a linear. And it sure can't hurt in a pileup either, if you know how
to work a pileup.


--
Caveat Lector - Honor Roll 2002


Some folks Wrote
No he didn't. 7dB, about one S-unit, is not enough to come to
anybody's
attention. . .

Yet look at all the people who go to all the trouble of putting up a 3
element beam, then think that the 7 dB gain over a dipole actually makes
their signal louder. Or get a 500 watt amplifier for their 100 watt rig.
Silly fools! Old wives!

Roy Lewallen, W7EL

Ah, c'mon. Reg says 7 dB isn't enough to worry about. "Kurt Sterba" said
that even 15 dB isn't. All the people who think that linears and beams
help their signals are just imagining things. The real experts say so.
You're not going to listen to the old wives, are you?

Roy Lewallen, W7EL
-- One of Reg's "Old Wives"

Caveat Lector wrote:
I would like to put a different spin on the 7dB statement below.

Where the extra gain or power really comes into play is very weak signal
DXing - not the pileups necessarily.

Cases in point - my Dxing log has several contacts where using a linear got
my signal far enough above the noise level for the DX station to understand
me. True on phone or CW. In most of these cases, the DX was calling QRZ and
no one was answering -- the DX station was so weak -- seems folks just gave
up or maybe everyone worked them. Turning on the linear got me the
contacts. Definitely Without Question - Worked an R1MV Malyj Vysotskij, HK0
Malpelo Is, VK9/M Mellish Reef, and VP8/G So Georgia by turning on the
linear feeding a vertical multibander.

I had this happen enough times to realize this to be the real benefit of
adding a linear. And it sure can't hurt in a pileup either, if you know how
to work a pileup.

Hi Roy -- reminds me of the time I worked an S79 on 15M phone. Very weak but
the contact was made. I posted the S79 on the DX packet cluster. A local big
gun came back at me with "Miniprop sez there is absolutely no propagation to
the Seychelles".

I replied Oh Gosh, I had better send the QSL card back when it gets here.
The QSL did arrive. I decided to keep it.

I have an old wife here -- don't listen to her either hi hi.

--
Caveat Lector -- I'll take an S-unit increase every time.



"Roy Lewallen" wrote in message
...
Ah, c'mon. Reg says 7 dB isn't enough to worry about. "Kurt Sterba" said
that even 15 dB isn't. All the people who think that linears and beams
help their signals are just imagining things. The real experts say so.
You're not going to listen to the old wives, are you?

Roy Lewallen, W7EL
-- One of Reg's "Old Wives"

Caveat Lector wrote:
I would like to put a different spin on the 7dB statement below.

Where the extra gain or power really comes into play is very weak signal
DXing - not the pileups necessarily.

Cases in point - my Dxing log has several contacts where using a linear
got my signal far enough above the noise level for the DX station to
understand me. True on phone or CW. In most of these cases, the DX was
calling QRZ and no one was answering -- the DX station was so weak --
seems folks just gave up or maybe everyone worked them. Turning on the
linear got me the contacts. Definitely Without Question - Worked an R1MV
Malyj Vysotskij, HK0 Malpelo Is, VK9/M Mellish Reef, and VP8/G So Georgia
by turning on the linear feeding a vertical multibander.

I had this happen enough times to realize this to be the real benefit of
adding a linear. And it sure can't hurt in a pileup either, if you know
how to work a pileup.

ml wrote:
i still ponder if i put power into a superconducting antenna if their
is no resistance, and a given about of power would therefore 'stay' in
the antanna longer ie no resistance and a sorta flywheel effect exists
the fields would have to exist longer for fixed-given power , ..

Using copper, the reflected current back at the feedpoint of a 1/2WL
standing-wave antenna is in the ballpark of 90% of the forward current.
Exactly how much improvement is possible?
--
73, Cecil http://www.qsl.net/w5dxp


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