On Thu, 07 Feb 2008 13:13:26 -0800, MGFoster wrote:

I'm in a vy antenna unfriendly area: an apartment in the air shaft of
the bldg. So I'm abt 40' from free-air on all four sides. Fortunately,
I'm on the top floor, so I'm trying to get a "stealth" antenna to place
on the roof: something that would be easy to set up/take down. The
helical fit that description. But, I'm running QRP (abt 5W) and, taking
into consideration what Roy said abt power & efficiency, I'm probably
not getting anything out.

You are getting out, however, by your low enthusiasm, it sounds like
you don't get much back in response for tossing out CQs. This may be
simply a matter of persistence because what you say more below
suggests not all is for naught:

One good thing abt this antenna is, for it's size, it does receive
better than the random-length wire (abt a 50' rectangle) I had been
using inside my apartment. It does have good bandwith - but, as Roy
stated this indicates low radiation resistance.

If you are receiving well, then you are not entirely boxed in - so to
speak (although it does sound like your apartment interior is shielded
by the building structure). You do sound like you have a lot of
height even if it is a air shaft.

Try an end-fed antenna (or work it against the ground of your three
prong plug). For that end-fed antenna, get a long fishing pole with a
reel full of flex-weave wire and a sinker. Mount the pole into a flag
mount so that it points out into the air shaft. Let the sinker loaded
wire drop into the shaft and drive the wire through your tuner.
Naturally, the longer the pole, the better - the more wire, the
better. Who knows, you might be able to tune-up by adjusting the
wire length. You can keep your existing antenna for listening (use a
T/R switch) and you are off and running. Don't worry about anyone
seeing it (especially at night) - they won't.

73's
Richard Clark, KB7QHC