Tom and all,
After spending 25 years in the military (Navy specifically), I can say, with a
fair amount of authority, that the antennas used by them are often used for
much different purposes than what people on this forum use them for..... he he
he. Never would a scenario arise where 1.8mhz DX would be of any interest
whatsoever to a guy in the field. He/she is most likely trying to make contact
with someone less than 200 miles away (and usually MUCH closer than that, like
over the next hill, but not within range of a vhf/uhf signal). Antenna
efficiency is often sacrificed for stealth..... again, for extremely obvious
reasons.
Long distance HF and MF comms are rarely of any concern these days, whereas it
is almost everything to us amateur radio ops. The T2FD antenna is one example
of a purpose built antenna whose intention was ALWAYS short range comms (NVIS).
It does what the military wanted it to do and then some. Same with almost
every antenna in the military's RF arsenal. This is especially true today
where high gain antennas, and "dx" type distances, are almost exclusively
devoted to vhf, uhf, shf satellites. Satcom is (and has been for a fairly long
time) ubiquitous in the military, as most of you probably already know.
Now, having said that, I used some absolutely dynamite antennas on HF while
underway. Simple antennas, like a horizontal end-fed that was roughly 60 feet
long and stood about 70 feet out of the water..... sea water..... Had a
practically infinite tuning range and could handle all the power that I could
feed it for phone patches and amtor (when we started using it). Needless to
say, in a situation where your horizontal (or vertical) is over salt water, in
the clear (no houses, trees or anything else to block the RF), and about 70 to
80 feet above that water is darned near a perfect reflective surface for a
horizontal ANYTHING, right?
Anyway, unless you want to talk about the military's advances in NVIS, which it
has done in spades, you are barking up the wrong antenna "source." If you are
wanting to do short range, NVIS, comms then DO take a look at military antenna
designs..... they work and they work well for that purpose, in particular.
There ARE antenna designs used by the military for backup long range HF
purposes, but they are mainly the same designs we all use for that
purpose...... efficient vertical radiators (think verticals over a SHIP's deck
as a groundplane, surrounded by salt water) or large log periodic beams that
are mounted at the top (or nearly so) of the highest mast on the ship, etc,
etc, etc. Again, those are really obvious and nothing new to us. So that is
my two cents..... keep in mind what the military wants its HF to do and those
much maligned military antennas are all of a sudden almost perfect for their
intended purpose. :) :)
Seven-thirds,
Mike AB7ZU
Kuhi no ka lima, hele no ka maka
On Aug 5, 2013, at 18:51, "Tom W8JI" <w8ji@w8ji.com> wrote:
>> Bingo! Just because the military does (or did) something with antennas
>> doesn't means it's good for us all to repeat.
>
> While Beverage antennas for transmitting are indeed one example, two more
> good examples are:
>
> 1.) that silly Maxcom antenna tuner sold from Florida, the thing that had the
> chopped up pieces of circuit board inside
> 2.) stainless steel terminated folded dipoles
>
> The problem with stuff like that is no one had actually quantified the loss,
> and even if they had, no one probably cared about signal levels. Just as long
> as they made contacts and the SWR looked OK, it was all "working".
>
> The same type of thing is what sells those magical CB rings and the little
> dipole parasitic elements (about a foot long) that go on CB mobile antennas.
> Anecdotal evidence is that it all works, just like healing rocks and deer
> whistles for cars. :) It all has an effect that people "feel" or find
> useful, so it all works at some level.
>
> 73 Tom
>
>
> _________________
> Topband Reflector
_________________
Topband Reflector
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