RadioBanter - View Single Post - Windom antennas

Mike Coslo · March 8th 07, 01:16 AM posted to rec.radio.amateur.antenna

wrote in
ps.com:

On Mar 5, 9:18 am, John Passaneau wrote:

We have used OFC dipoles here for a few years at field day. They fill
a very specific set of needs for us. 1) They are simple to put up
2) The feed line coming from one end of the dipole is shorter than
from center feed dipoles in our setup. 3) OFC dipoles offer an
impedance at the end of the coax that is within the range of the
tuners built into our radios on the bands that are important to field
day. This simplifies our setup and operation. 4) They work as well as
an antenna of that physical length on any one frequency would no
mater how it's feed.

The radiation pattern from an OFC is set by the length of the wire
not where RF is feed in/out of the antenna. In our setup open wire
line and tuners would be a pain in the butt, and an operational
inconvenience that gains us nothing. Fan dipoles or separate dipoles
are hard to setup and or tune and would perform no better for us. The
antennas we use were built by myself and use a 4:1 current balun
which minimize feed line radiation. On 80/40/20m we can easily match
the antenna with the built in tuners so the SWR must be under 3:1.
OFC dipoles don't work well on 15m but with the current sun spot
cycle not a problem. We see no indication of common mode current
problems, so we don't worry about it, we just operate and have fun.

John W3JXP

Sounds fine... Just as long as I don't have to use it.. Myself, I
prefer either
separate, or fan dipoles on the low bands.. 20-10, a tribander.. "A4S"
I never use a tuner. All coax fed too... To each his own I say...
MK

I have worked with one of John's OCF dipoles on the FD night shift,
and hold and run frequencies on 75 meters all night long - with 100
watts. Can't say the exact performance of the antenna, but if I'm
holding a frequency along with the big guns on a busy day, it isn't
too bad at all.

OCF dipoles are obviously a compromise. As a multiband antenna it
better not outperform a specific band dipole.

If you have found such a *drastic* difference however, perhaps
there was something wrong with your particular antenna or setup?

- 73 de Mike KB3EIA -