In article Gj4qc.43044$pJ1.24343@lakeread02,
Jack Painter wrote:

Remember that the military does two things. One is NVIS which
has the antenna mounted about 1/4 wavelength above ground. This
gives a good ground effect from 2 MHz to 12 MHz out to 300 miles.

The other is ALE, automatic link, which switches frequencies
automatically to insure the best path. An antenna with tuner
would just be too slow.

David, even for purposes of this discussion, that is a bit oversimplified.
Perhaps that type of broadband temporary antenna installation is acceptable
for field units, but have never seen one of them in a permanent
installation.

My wife and I recently spent several weeks touring around Peru (just
got back last week).

I was intrigued to observe a _lot_ of modest-size HF wire antennas
scattered around... and these all appeared to be of this same basic
"terminated, folded dipole" variety. I saw a couple at the Cuzco
airport, one at a village on the Amazon, one or two in Aguas Calientes
(the village right below Machu Picchu), etc. They were usually
mounted in an inverted-V configuration, and appeared to be permanent
installations rather than short-term field-use installations.

The applications were probably NVIS, with working ranges out to a few
hundred miles.

I can't say for certain that they _were_ T2FDs, as I had no way to go
up on the towers and confirm that the device at the center of the
upper part of the dipole was a terminating resistor. I've never seen
a folded dipole with an open-circuiting insulator at the center of the
upper span, though.

My guess is that these antennas were chosen because of their "one size
fits all" nature - they can be installed and used without trimming,
don't require SWR-matching at the transmitter, and their relatively
low efficiency may not be an issue in these applications.

--
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!

They conform to the manufacturer's specifications.

But the manufacturer's specifications do not mention, at least in numerical
terms, the most important parameter - antenna GAIN.

The omission can mean only one thing - very poor gain at the lower
frequencies.

But that is easily corrected by pumping in 10 Kwatts.

David,
Huh! I would have sworn that was just what was asked.
'Doc

"R. David Steele" wrote in message

Remember that the military does two things. One is NVIS which
has the antenna mounted about 1/4 wavelength above ground. This
gives a good ground effect from 2 MHz to 12 MHz out to 300 miles.

The other is ALE, automatic link, which switches frequencies
automatically to insure the best path. An antenna with tuner
would just be too slow.

David, even for purposes of this discussion, that is a bit oversimplified.
Perhaps that type of broadband temporary antenna installation is acceptable
for field units, but I never noticed one of them in a permanent (U.S.)
installation. I happen to be around several hundred HF antenna
installations, and neither NVIS nor ALE operating units use anything of the
kind. Maybe you were referring to field units, as above, not sure. Also,
ATU/couplers are always used for ALE systems, with the memory-response times
measured in milliseconds. This applies to air, ground and marine units for
all armed services. There is no magic antenna for all bands ALE, and units
using NVIS would have little need for ALE. That doesn't
mean the military hasn't wasted money on it somewhere for short range use,
it just wouldn't realize it's potential for reliable medium to long range
linking.

73,

Jack Painter
Virginia Beach, Va

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"Mike" == Mike Coslo writes:

[... David mentioned B&W antennas ...]

Doc David, The bottom line is that it's a terrible 'amateur' antenna
Doc for the price. 'Doc

Jack Out of curiosity, what other antenna provides a better
Jack cost-benefit ratio while maintaining the same constraints with
Jack respect to power, size, and construction?

Mike Hmmm, How about an Isotron? 8^) Man, there is a small antenna!

They're too spooky for me. I don't understand how they work.

Mike If you take the bands that the B&W performs adequately on, the
Mike size ratio between it an a halfwave dipole isn't quite so
Mike good. I suppose the FD that is most comparable to my antenna is
Mike the BWD 90. It's 90 feet, as we might figure. My dipole is 96
Mike feet.

I guess it depends on what you consider "adequate". If your 96-ft
dipole provides comparable SWR matches across all the bands the B&W
antennas allegedly provide, that'd be pretty impressive. Like the
other poster, I noticed that there were no gain figures in the B&W
literature, and that does make me suspicious.

Mike My dipole cost less than 30 dollars to make. If you count the
Mike tuner, I still spent less money.

Sure, so did I. And my antenna was messed up the following spring,
due to stretched wire, water leaking into critical bits, and more. If
you spent less than thirty dollars and used copperweld or stainless
steel, then I'd like to know what trucks that wire falls off so I can
chase them around town.

Mike - Mike KB3EIA -

Jack.
- --
Jack Twilley
jmt at twilley dot org
http colon slash slash www dot twilley dot org slash tilde jmt slash
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Jack,
'AES' has copperweld, 18 ga., 250 feet, about $18.00. No
idea where to find stainless steel wire, don't need it...
'Doc

Jack Twilley wrote:
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"Mike" == Mike Coslo writes:


[... David mentioned B&W antennas ...]

Doc David, The bottom line is that it's a terrible 'amateur' antenna
Doc for the price. 'Doc

Jack Out of curiosity, what other antenna provides a better
Jack cost-benefit ratio while maintaining the same constraints with
Jack respect to power, size, and construction?

Mike Hmmm, How about an Isotron? 8^) Man, there is a small antenna!

They're too spooky for me. I don't understand how they work.

No majik there, they work about as well as you would expect an antenna
that size to work. That is, not very well. They look cool though!



Mike If you take the bands that the B&W performs adequately on, the
Mike size ratio between it an a halfwave dipole isn't quite so
Mike good. I suppose the FD that is most comparable to my antenna is
Mike the BWD 90. It's 90 feet, as we might figure. My dipole is 96
Mike feet.

I guess it depends on what you consider "adequate". If your 96-ft
dipole provides comparable SWR matches across all the bands the B&W
antennas allegedly provide, that'd be pretty impressive. Like the
other poster, I noticed that there were no gain figures in the B&W
literature, and that does make me suspicious.

Right, the two antennas are not quite comparable. I have to use a tuner
on my antenna. But that really isn't a handicap IMO. I contest with my
rig, and although I have to be careful on 80 meters, I can change bands
and set the knobs to their proper positions in just a couple seconds.


Mike My dipole cost less than 30 dollars to make. If you count the
Mike tuner, I still spent less money.

Sure, so did I. And my antenna was messed up the following spring,
due to stretched wire, water leaking into critical bits, and more. If
you spent less than thirty dollars and used copperweld or stainless
steel, then I'd like to know what trucks that wire falls off so I can
chase them around town.

Never used copperweld, except for twinlead. You can get it pretty
easily though.

The trick with regular copper is to pre-stretch it. You get a helper or
two on each end, and give a good steady pull to stretch it.

And yeah, Mother Nature can be a b***h sometimes. My dipole has been up
over 2 years now, and is still surviving. That is probably as much luck
as my construction genius! 8^) I'll be taking it down for some
modifications - I'm going to lengthen it so I can tune 80 meters better,
so I'll see soon how the plastic parts held up.

I think what I am driving at here is that everything comes at a price,
some monetary, some functional. Antennas like the B&W FD are great if
you want minimal fuss. That comes at a price in performance though. I
went real cheap. The price I pay is using a tuner. That doesn't bother
me at all - I'm an inveterate knob twiddler!

- Mike KB3EIA -

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"Mike" == Mike Coslo writes:

[...]

Mike I think what I am driving at here is that everything comes at a
Mike price, some monetary, some functional. Antennas like the B&W FD
Mike are great if you want minimal fuss. That comes at a price in
Mike performance though. I went real cheap. The price I pay is using
Mike a tuner. That doesn't bother me at all - I'm an inveterate knob
Mike twiddler!

I wholeheartedly agree. There's a price to be paid for every setup --
if you're not paying out of your wallet, you're paying out of your
time, or out of your loss of capabilities. It's one of those basic
facts of life. I also went dollar-cheap, and I'm getting what I pay
for. I'm considering going for something like the B&W for my next
location should it be appropriate, to see if I can get my money's
worth out of it. Worst case, it ends up getting sold second-hand on
eBay. Best case, well, we can all dream. :-)

Mike - Mike KB3EIA -

Jack.
- --
Jack Twilley
jmt at twilley dot org
http colon slash slash www dot twilley dot org slash tilde jmt slash
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On Tue, 18 May 2004 14:31:17 -0700, Jack Twilley Wrote :
snip


I wholeheartedly agree. There's a price to be paid for every setup --

Same old story isn't it - "cheap", "well made" and "effective" - choose
any two. ie. If it's cheap and effective it aint gonna last...:-)


--

Humbug

Jim Higgins wrote:
On Sun, 16 May 2004 21:13:58 GMT, in
, R. David Steele
/OMEGA wrote:


http://www.bwantennas.com/

The military is using these antennas because of ALE (automatic
linking) and NVIS. I gather that while they are very broad
banded, they have less the best gain?

Any feed back?


I tend to compare the claims for any antenna to the
characteristics of a dummy load and then remember the principle
of reciprocity.

So for the BW dipole let's see. It's really quiet, esp on the
lower frequencies. It's really broad banded. It's not for me.


Dummy loads are pretty quiet too aren't they? ;^)

- Mike KB3EIA -