[Elecraft] OCF antennas

[John Oppenheimer]

This thread has a count of 15. I thought I would squeeze one more in
before the end of thread is called.

Last year I performed some simple OCF Dipole investigations. My quest is
to make a 15/20 trapped OCF dipole to place in an asymmetrical location
in my attic. My rather incomplete notes can be found here:
http://www.kn5l.net/ocfda/OCFDA.pdf

My general finding for a OCF Dipole antenna are:

EZNEC models, with accurate AGL parameters (including the Vee shape),
are highly predictive within my ability to measure antenna parameters,
Autek Model VA1 and KAT2 SWR meter.

Best I can tell, a dual core 4:1 Balun does shunt coax shield currents.
My observation is based on the EZNEC modeling versus actual measurements
and noting that changing the feed-line length did not alter the measured
antenna parameters.

The off center ratio is highly dependent on antenna height for a
relatively low antenna. So much so, that a single set of values will
probably not be suitable for an application. If one wants to put up an
optimal OCF Dipole, then you may want to use a modeling program or be
prepared to perform a bunch of at location measurement and cuts to find
the optimal values.

A OCF Dipole does seem to work. I worked T32C using my K2/10 and the 15
meter OCF Dipole investigation antenna in my back yard.

John, KN5L