[Antennas] Re: T2FD

[Martin Ewing]

A few comments on the terminated folded dipole, 
called T2FD when tilted.  I have been using the 90 ft
B&W version for several years.

First, I think the Cebik analysis at
http://www.cebik.com/wbfd.html is very useful.  He
also has an earlier note on the T2FD version at
http://cebik.com/t2fd.html.

The takeaway for me is that the antenna begins to fall
apart at 4 MHz as you lower the frequency.  Above 4
MHz, you "only" have a loss of 3-6 dB.  B&W has
marketed this antenna for 160 M and up.  That's a big
stretch!

The big benefit is that you get "useful" performance
from 40 - 10 M and "some" performance at 80 M -- all
in one antenna at a manageable SWR.

So what about that 6 dB loss?  That's 1 S-Unit.  How
many QSOs are impossible if you cut your power by 1
S-Unit?  Some, but not most - IMO.  On the other hand,
6 dB means that 1/4 of your power goes into the air,
while 3/4 goes into the terminator!  No good for QRO.

I recall the QST article a few years back about using
a lightbulb as a broadband antenna.  The good news is
that the terminated folded dipole is a lot better than
a lightbulb, except maybe on 160 M. (On the other
hand, you can read a newspaper with the lightbulb. :-)

I recently put up a 3-el SteppIR at 40 ft, and the
world came alive on 20 M.  I gained about 2 S-Units on
receive, and I started getting compliments on a big
signal in Europe (with 100 W).

I have to admit that one reason I put up the folded
dipole in the first place is that it _looks_ neat. 
Like a 1930's installation... The main reason was that
I could get all bands, including WARC, with just one
installation.  And I'm a closet QRPer.  

But it feels so good when you put up an efficient
antenna.

73, Martin, AA6E