We have developed a way to "side feed" a combo of a vertical or inverted L
wire aerial over an FCP (5/16 wave single wire folded counterpoise). Until
now for radials or an FCP, the feed is at the bottom of the aerial wire
where it attaches to the center of the FCP or radials.
The alternate feed is at the three wire end of the 160m 66 feet (or 80m 33
feet) FCP instead of the middle. This is done at the outer end of the FCP's
first 1/16 wave where it folds to come back to center and opposite end. An
isolation transformer is still required.
An advantage is that the feed point is now not directly below the vertical
wire. With the FCP up 10 feet, the ground underneath can be used normally,
without buried wire or cable or support posts, and the feed end of the FCP
located more favorably for feed line.
Done upside down, FCP on top suspended from up a tower, vertical wire
hanging below from FCP center, an upside down 80m four square can be
constructed with this side feed method from a tower or catenary where the
RF current maximums are up in the air away from lossy ground at top of
vertical wires, with shorter paths to open air through tree tops, and
without need for complex buried radials underneath.
A disadvantage is that 160/80 dual-banding of a 160 L over FCP cannot be
done with this feed method. The dual-banding requires "flipping" the FCP's
operating band with a relay in the center, mandating the usual center feed.
A few years back the reflector moderator specified that detailed
discussions regarding an FCP are not to be held here. Other venues will be
used. Reply *off reflector* to k2av [at] contesting.com or k2av [dot] guy
[at] gmail.com for information and inclusion.
73, Guy K2AV.
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|