Jack Twilley wrote:

So who actually has the space and resources to set up an ideal
horizontal dipole on HF with the full length and height as specified
in all the formulas? Wouldn't it be cheaper and easier to set up a
vertical if you could install something that high off the ground?

The only thing I've seen personally that looks like it meets the ideal
is a small station tucked into the northeast cloverleaf of an exit off
Interstate 93 near Boston, MA, and the station appeared to be a marker
for Logan. Anyone have any personal, real-life experience with a
full-size, full-height HF dipole? Is it worth the cost?

Jack.
- --


Interesting question. I have seen the dipoles used for HF communications
with transatlantic air traffic from Gander, or at least one site which
IIRC was the receiver site. Since this, and similar installations around
the world, need reliable communications at a number of frequencies to
provide coverage over a wide area and while they may have a kilowatt or
so for transmit; on receive they are working with a station whose
transmitter is unlikely to exceed 400W PEP and whose antenna is at best
a poor compromise since the days of aircraft wire antennas are long
gone.

I don't know about other sites, but Gander certainly used to have a
number of just plain old dipoles; and I have seen other simple dipoles
at several other airports and airline installations so one would expect
a fair amount of operational data to have been gathered over the years.

It seems to me that most of the professional vertical installations I
have seen are those which tend to require operation at multiple
frequencies with a single antenna - i.e. shipboard and military
installations, although there used to be quite a lot of verticals at
Coast Guard stations for the 2 MHz band.

Re. the installation at Logan; I would be inclined to believe that what
you are seeing is a top loaded "T" configuration for a Low Frequency
(200 - 400kHz) Non-Directional-Beacon.

Dave

On Fri, 14 May 2004 20:44:40 -0400, Dave Holford
wrote:

Interesting question. I have seen the dipoles used for HF communications
with transatlantic air traffic from Gander, or at least one site which
IIRC was the receiver site. Since this, and similar installations around
the world, need reliable communications at a number of frequencies to
provide coverage over a wide area and while they may have a kilowatt or
so for transmit; on receive they are working with a station whose
transmitter is unlikely to exceed 400W PEP and whose antenna is at best
a poor compromise since the days of aircraft wire antennas are long
gone.

I don't know about other sites, but Gander certainly used to have a
number of just plain old dipoles; and I have seen other simple dipoles
at several other airports and airline installations so one would expect
a fair amount of operational data to have been gathered over the years.

I worked at a station in Alaska that had a big antenna farm. The
station was designed to communicate with aircraft over distances from
zero to thousands of miles. We had very few limitations over what we
could do or build with unlimited space, and had two rhombic's for
communicating with two flights that took the same track every day.
Communication was mostly CW five letter group encryption. The
transmitters and receivers were separated by 20 miles or so.

The operators could choose which transmitter/antenna combination gave
them the best performance. The dipoles seemed to be the preferred
antenna. The rhombic's (the king of HF antennas) were seldom used,
probably because of the radiation pattern. The antenna is the most
unpredictable part of any installation.

I was the guy that tried to neutralize the big triodes, so you know
that was a while ago. (1950's). The globe was about the size of a
volleyball.

Ron, W1WBV

Jack Twilley wrote in message ...
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

So who actually has the space and resources to set up an ideal
horizontal dipole on HF with the full length and height as specified
in all the formulas?

Thats all I use here.

Wouldn't it be cheaper and easier to set up a
vertical if you could install something that high off the ground?

No.

The only thing I've seen personally that looks like it meets the ideal
is a small station tucked into the northeast cloverleaf of an exit off
Interstate 93 near Boston, MA, and the station appeared to be a marker
for Logan. Anyone have any personal, real-life experience with a
full-size, full-height HF dipole? Is it worth the cost?

If you run a full size dipole, "I prefer coax fed in general", you
have a full sized dipole signal with very little losses. Well, unless
you have 500-1000 ft of coax... What more can I say... The antenna
cost is cheap. Wire and coax. I'm on a city lot. I presently have
160m,80m,40m dipoles up in parallel. Fed with one coax. The 160 dipole
is in a Z layout to fit the lot. The 80 and 40 are in straight lines
as normal, but spaced apart a good bit. Myself, I don't use anything
but full size coax fed dipoles, unless it's impossible. As far as
single band dipoles go, anything less is a step down as far as I'm
concerned. Loss wise and also ease of use. No tuner, no weather
hassles, etc...When I switch bands, there is nothing to do but key the
radio. MK

"Jack Twilley" wrote

So who actually has the space and resources to set up an ideal
horizontal dipole on HF with the full length and height as specified
in all the formulas? Wouldn't it be cheaper and easier to set up a
vertical if you could install something that high off the ground?

I thought a 1/2 wave dipole was "the standard". Standard meaning the
traditional use of the dipole for efficiency and common use. I did not know
it was a significant compromise from a full wave length long antenna which
would be impossible to install in most backyards when you talk about 60
meters or higher. If a full wave length dipole is common I never see
references to it either.

Jack Painter
Virginia Beach VA

Has anyone got an ideal ground ??

Nick