I am seeking advice on improving an apartment HF antenna, and I know
that people who work 160m are experts on various loading schemes.
While I don't seriously expect to work 160m, I can apply your ideas to
my situation. I think I MAY be able to work 80m. At the very least, I
can make my antenna more efficient on 10m through 40m.
As you know, a capacitance hat is a way to obtain resonance with an
antenna shorter than 1/4 wavelength. Any sheet of metal attached to
the top of an antenna can be used as a capacitance hat.
The question: How do you secure a capacitance hat to the top of an
antenna? Since adding a capacitance hat (especially one of the big
ones sold with the Texas Bugcatcher antenna) makes an antenna VERY top
heavy, something is needed to keep the capacitance hat and/or antenna
whip from tipping, sagging, or collapsing. In other words, capacitance
hats pose a serious MECHANICAL challenge.
I am using a DK3 Screwdriver antenna in my ground floor apartment.
(The ground plane is a 64"x72" sheet of spliced aluminum foil attic
insulation.) Due to the 8-foot ceiling above my patio, I am using an
even shorter whip antenna than the one recommended by Don Johnson. As
a result, I cannot get resonance on 80m. However, I believe that a
capacitance hat a few feet across might provide me resonance on 80m (or
at least make my antenna more efficient on 10m through 40m).
Jason Hsu, AG4DG
Please send all personal messages to jason_hsu@planetmail.com
--
FAQ on WWW: http://www.contesting.com/FAQ/topband
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|