Hi Cecil

Yes I was very interested in your design. I saw it some months ago and
discarded it from the standpoint of being too long. One of the other big
differences too is that you are using feedline to offset the antenna
reactance whereas I am feeding a resonant antenna albeit at higher and
higher Z as the freq goes up. I only need to transform the Z.

I said "avoid" switching things in and out, but I can see that I am just
going to have to get a box and put something together. I was thinking a
broadband balun with maybe taps for diff frequencies or separate baluns.
I was hoping someone would present me with a "all in one" balun design
that would do it all! grin I was also thinking of using switched coax
based baluns (say 4:1's) but thought it a bit messy. The other "dream"
was somehow coming up with a magical lengths of some strange Z coax (say
RG62) and switching them in and out like your open wire design... (eg
1/4 wave Q sections 75r coax at 20m, 92r coax at 15m, 4:1 coax balun at 10m)

Some other notes

If I direct feed the antenna at 40M it only has a VSWR 2:1 BW of about
100kHz. I was already thinking of attaching a geared down
motor/fibreglass rod to roll up some of the antenna conductor (tinned
copper braid) for tuning. This would also serve to make up differences
on other freqs.

For those that queried NVIS not being so useful at a higher frequency.
This is more a case of making something work in the space available. The
loop is actually a very strange shape that roughly looks like a triangle
sloping down at maybe 30degrees. (The way the ground slopes) I havent
tried to model it but I would asssume that some radiation at harmonic
freqs would be desirably closer to the horizom.

Thank you all for your comments.

Cheers Bob VK2YQA


Cecil Moore wrote:
Bob Bob wrote:

I want it to be "no tune/no ATU" and to avoid switching things in and
out.


Bob, if such existed, almost everybody would be using one. The best
I can offer is switched lengths of feedline, depending upon what
band you are on. For a 40m dipole, 1/2WL of ladder-line. For a 40m
dipole used on 20m, 3/4WL of ladder-line is about right.

I run a 130 ft. dipole on all HF bands with no tuner (per se) simply
by switching lengths of ladder-line. Take a look at my web page.