[BC] KKGM

[Dan Strassberg]

Resending this because the original bounced but it may have reached some of
the addressees.

1. What is the efficiency of a 263+-degree radiator SUPPOSED to be (in
mV/m/kW @ 1 km), assuming a normal (120 quarter-wave-radial) ground system?
It is presumably less than the efficiency of a 225-degree radiator with the
same ground configuration. I have never seen theoretical efficiencies for
standard series-fed radiators of heights greater than 225 degrees
(approximately 440 mV/m/kW @ 1 km). Also, what does the vertical-plane
radiation pattern look like?

2. Is there a practical way to electrically shorten such a radiator? For
example, can you attach a skirt to the bottom and drive it so that the
skirted section (in this case something between about 40 degrees and 100
degrees) does not radiate?

I've been trying for several years now to find someone who can comment on
electrically shortening AM towers that are too tall for a diplexed station
operating at a frequency higher than that of the station that originally
occupied the tower. KKGM is now the second case I've heard of of a tall
tower that proved to be too tall and provided very poor efficiency. The
other, in central New York State, did not, AFAIK, even meet Class C minimum
efficiency (241 mV/m/kW @ 1 km) and defied the ministrations of several
well-known consultants. I don't know whether it is yet working as the
original consultant intended.

--
Dan Strassberg, dan.strassberg at att.net
eFax 707-215-6367