Peter Martinez wrote:
Effectively what Dick is suggesting is having the coil physically at the
bottom where it can be housed and adjusted, but electrically at the top.
This is done by extending two wires down the antenna such that the
currents in these two wires are equal and opposite and they therefore
make no contribution (or degradation) of the antenna performance. If
the antenna is electrically short anyway, it doesn't help to say this is
a stub with a specific electrical length, it's just a coil connected
into it's place with a pair of wires.
If the antenna was hollow, or like a lattice tower, the wire from the
top hat could come down to the bottom inside the structure, so long as
it didn't arc across!
This type of antenna is what I used for WD2XKO during most of the past
winter. It seems to work well. A US patent was issued which covers
this design. A link to the patent is on the WD2XKO web page at:
http://www.w4dex.com/wd2xko.htm
Dex,
W4DEX / WD2XKO
|
