"C. J. Clegg" wrote in
news
On Wed, 22 Nov 2006 01:01:56 +0000, Dave Oldridge wrote:

The loaded folded dipole idea is actually quite efficient if you stay
above the "knee" frequency. This is about .5 wave at the lowest
frequency.

Good evening, Dave.

But, isn't there another frequency, around 1 full wavelength at the
operating frequency, above which efficiency starts to go to pot again?

I didn't see this. But as the size increases, the pattern tends to start
to come apart.

125 ft (which you suggested in another message) is a full wave at
something a shade under 8 MHz, well within my upper limit of 9 MHz.
So, how will a 125-foot T2FD operate in the range of, say, 7 to 9?

Actually, I just modelled it. The 125-foot version is very good between
7 and 9, but the SWR (with a 650 ohm terminator) jumps to 4 to 1 at 5.25
mhz. Like I suggested, you need to model your actual situation, then
build to the model.



--
Dave Oldridge+
ICQ 1800667