In message
,
Lime Light writes
On Jun 23, 11:48*am, Jon Teske wrote:
The B&W, which comes in several configuations, is a pretty standard
military antenna. We had several of them on various buildings at Ft.
Meade, where I worked and I've seen them on military posts all over.
Several other commands at Ft. Meade also had them. I've also seen then
at some local reserve armories as I drive by them.

With an antenna tuner (usually automatic) they can cover the whole HF
spectrum.

As it is a government issue, it likely can be made by several vendors
to government specs and then bid upon, unless there is something so
unique about it that it is a sole source contract. *Some of them I
inventoried when doing site inventories ( I was a US Dept. of Defense
program manager) were, in fact sold to the gov't by B&W which I
believe is short for Barker & Williamson who made ham transmitters in
the 1950's when I was both a kid and first licensed.

I'm not an antenna engineer by any means but someone who was said that
essentially is was a sort of hybrid between a Zepp and a folded
dipole. The extra spacing contributed to its bandwidth. He said the
center had some sort of insulator with a balun transformer. *It was
not the most effecient antenna, but could be erected quickly and was
packaged with a mast kit for field operations.
The military version also had the option of stainless steel wire.
Most of the ones I saw were permanently installed.

I was always curious about them, but all my projects were receive-only
for intercept so I never got to play with them at all.

Like to hear more about them.

Jon W3JT

They're found on the roof tops os US Embassy's as well. If the design
incorporates a resistor there will be additional loss, but that is the
trade off when you need a multiband antenna that plays well with ALE.

We were issued dipoles which had to be retuned with each frequency
change through out the day. Sometimes efficiency isn't everything.

Do a Google on "T2FD", and you will find lots of information on this
antenna. I believe the Cebik did an analysis of it, but his articles are
not as accessible as they used to be.
--
Ian