Of course Mr. Clark, as usual, is "right on the money" in saying that 1db is
nothing. To get a 1 unit s-meter difference on the average receiver, it
actually takes 6 decibels more signal, or 4 times the power, from the
transmitter, to produce that signal increase.

Double the transmitter power (3 db) , and you get a half an s-unit increase.

In many cases, it is more advantageous to raise the antenna 10 feet or more,
than it is to increase transmitter power, and it will often result in much
more signal in the receiver, since it gets the transmitter antenna "up in
the clear", where losses to the ground and surrounding obstructions drop
off..


"Richard Clark" wrote in message
...
On Tue, 11 Jan 2005 03:30:07 GMT, ml wrote:
what would happen if i build say i'd have to stay physically small , so
say a 1/4wave verticle on 10m and then made that antenna
supercondutive?

Hi OM,

As far as performance? Absolutely no difference to it even if it were
elevated 1000°F above that to compare.

- Well maybe someone with enough sophisticated equipment might notice
a dB difference - then they would whack the side of the gear to clear
that up - nope, no difference....

You need to come to terms with just how imperceptible 1 dB is (zilch,
in technical terms), and how much power it takes (about 12%, just more
$ to burn) to make that imperceptible difference. The dollar has lost
30% of its value in the world market in the last few years - have you
noticed? This may not be one way to appreciate 1dB, but it does
reveal how relative changes go unfelt.

73's
Richard Clark, KB7QHC

Zombie Wolf wrote:
Of course Mr. Clark, as usual, is "right on the money" in saying that 1db is
nothing.

Reminds me of an article in QST in the '50's titled
"One dB Doesn't Matter" or something like that. This
ham had one dB loss due to an old final tube, one dB
loss due to a dirty tank coil, one dB loss in the low-
pass filter, one dB loss in a bad solder joint, one dB
loss in the tuner, one dB loss in the transmission line,
and one dB loss in the antenna. He wondered why he
wasn't getting out very well. :-)
--
73, Cecil http://www.qsl.net/w5dxp


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Reminds me of an article in QST in the '50's titled
"One dB Doesn't Matter" or something like that. This
ham had one dB loss due to an old final tube, one dB
loss due to a dirty tank coil, one dB loss in the low-
pass filter, one dB loss in a bad solder joint, one dB
loss in the tuner, one dB loss in the transmission line,
and one dB loss in the antenna. He wondered why he
wasn't getting out very well. :-)
--
=============================

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

It's less than the difference between a G5RV plus coax, specially a 1/2-size
G5RV, and an ordinary dipole fed with open-wire line which most people never
seem to notice.
----
Reg, G4FGQ

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

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?
. . .

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.

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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