[Antennas] To anyoine made T2FD antennas

[Ed Tanton]

Hi Zach... I have extensive experience with the commercial T2FD: the B & W 
version(s) of the T2FD <http://www.bwantennas.com/>. Presently I have the 
"BWDS-1.8-30 Broadband Folded Dipole" which is essentially a 90ft (~28M) 
folded dipole made of stainless steel, with a balun feed, and a loading 
resistor in the center of the top line.

Answers to your questions are:

1. Electrically (RF-wise), there will be VERY little difference between #12 
and #14.

2. Electrically (RF-wise), there IS an end-effect between wire and a 
non-conductor, but (especially with this antenna) I would not worry about 
it. Why don't you get some 1/4 inch (6.35mm) UV-Resistant DACRON for this. 
I do not believe IT will be broken by the forces you describe. I have HEARD 
very good anecdotal remarks about 'grass-cutting-cord', although I myself 
have not tried it, and prefer using 3/16" (4.8mm) UV-Resistant Dacron. 
(Although for an antenna the size of my B&W, or for your with all that 
wind/etc. I'd step it up to the larger 1/4 inch (6.35mm) size.

3. I cannot imagine how an "aircore balun for VHF" could be used 
successfully at HF. Bencher makes an excellent air-core balun, and there 
all the other types being sold, as well.

4. As for problems using the 75 ohm coax... you have an automatic 
SWR-derived loss. Can it be overcome with a preamp on receive and more 
power on transmit? Yes... BUT... it seems a waste to take the losses. If 
that's what you have, it will work.

Now for some general comments about the T2FD antenna.

First, if you use it as B&W ~recommends (as a level-e.g. NOT 
tilted-dipole), it will not equal a regular dipole (fed with coax) on 
whatever specific frequency you have built it for. If you feed it with Open 
Wire Line (OWL), and use a balanced-line tuner; the 'regular' dipole will 
beat the B&W every time. How MUCH it will beat the B&W is calculable, 
more-or-less, but probably enough to notice (which is my favorite 
real-world-test.) When using a tuned, receiving pre-amp; I doubt seriously 
there would EVER be a signal you could hear with the 'regular' dipole and 
not hear with the B&W T2FD.

Second, when you tilt the thing, the whole ballgame becomes difficult. I 
believe that a "genuine" T2FD ** MUST ** be a tilted antenna. Else, it's 
just a "Broadband Folded Dipole". I also believe that, once tilted, there 
are F-B improvements that make it a very interesting antenna. Whether what 
all I believe is a matter of fact, I cannot say, for I am only describing 
generalizations of what I recall having read.

So, if I am not tilting my 'BWDS-1.8-30 Broadband Folded Dipole' why am I 
using it? Because I want to have available a single antenna I do not have 
to add a tuner for, that I can use for HF reception, instantly, anywhere 
within it's frequency span.

I believe that for 'ordinary' ham radio use-as opposed to SWL 
reception-only-a G5RV or an Extended-Double-Zepp make a much better general 
purpose antenna. The resistor in either a T2FD, or the BWDS-1.8-30 
Broadband Folded Dipole, is going to absorb some power-in either direction 
(RX or TX) and that is just not acceptable to me for transmitting. On 
receive, it's just not a big deal. On transmit, it seems like a waste. If I 
was an embassy, and either spread-spectrum HF transmission or at least 
near-instantaneous anywhere-HF capabilities were important, the B&W would 
make sense as an "only" antenna. At home, it makes sense to me as the 
secondary, no-tuner SWL I described.

I hope this helped your thinking a bit. If you want to get nearly 
indestructible spreaders, get fiberglass. My friend Allen Bond, WB4GNT, 
sells fiberglass tubing, rods, and such, and has a company at: 
<http://www.mgs4u.com/> . I highly recommend him.


73 Ed Tanton N4XY <n4xy@earthlink.net>

Ed Tanton N4XY
189 Pioneer Trail
Marietta, GA 30068-3466

website: http://www.n4xy.com

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