Topband: tree losses

[Mike Armstrong]

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 at 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