Richard Clark wrote in
:

On Sun, 09 Sep 2007 22:51:54 -0400, RJG wrote:

I bought 2 Slinky's to put a Slinky antenna together, and would love
to get comments and suggestions, (construction detail tips, care and
feeding, etc.) from anyone who has tried this type of antenna before.

I live in a second floor apartment and have limited HF antenna
options. I would love to hear recommendations for any other HF antenna
designs that would work well in this type of setting.

Classic wire-wound, air-cooled resistors.

You could do better with the various 1 meter diameter loops sold
commercially. Some might suggest mobile screwdriver designs clamped
to your balcony railing, but that isn't really the same sort of metal
bulk equivalent to a, say, Chevy Suburban which would be the principal
radiator. On a comparable price basis, the loops will be a better
investment for 40M and up (I don't recall any that suggest they cover
80M and certainly 160M is beyond the realm).

I made a 160m loop out of LMR400, using the capacitance of the inner-to-
outer conductor to resonate it. Made it two turns and wound a gimmick
match out of flat 4-wire phone cable onto it to fire it up. Very narrow,
but reasonably effective. Better than a hamstick, I think. It's about 3
feet in diameter.

My normal 80-10 meter set-up is a hamstick horzontally off the balcony
rail. The rail backs onto a stucco wall with underlying mesh, so the
"ground" although tilted sideways is vastly larger than the average car.
I'm going to try a screwdriver there because I like the idea of being
able to change bands from the operating position instead of needing to go
outside in whatever weather is happening at the moment.



A simple test for small (for their wavelength) antennas is to measure
their bandwidth. We will take the Slinkies as an example (and
certainly cheap enough to test this statement, and to see how they
perform both). A small antenna that would be efficient will also
exhibit a high Q. The loops mentioned, as I recall, generally exhibit
5 to 10KHz bandwidth. For the most part, they exhibit some of the
better efficiencies (although not as high as a standard dipole).

Yes, my 160m loop is almost too narrow for SSB.


--
Dave Oldridge+
ICQ 1800667