ND2X/5
(Generally Mobile)
uses KB6KQ
Antennas on 6m, 2m, 135cm & 70cm
(An "Unsolicited Testimonial!")
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I use both a 1/4 wave vertical (on the roof of the cab, toward the
rear) and a KB6KQ Halo on 6m; I switch between them with a manual coax switch in the cab of
the pickup. I have tried three different horizontally polarized antennas for 6m mobile
operation, and the KB6KQ 6m loop turns out to be the best performer for me, read-to-go out
of the box (6M requires assembly, but does NOT require testing or tuning); simply install and
use! The 6M Loop fits between the stacked 2m loops, and neither antenna system "sees" the
other.
I tried six different horizontally polarized antennas for 2m mobile operation over a period
of five years and, again, the KB6KQ loops turned out to be easy to install and use, especially
if using the available KB6KQ phasing harness. They outperform the others ("A/B" comparison).
One model, made by K5DDD, performs as well for communication, plus covers the entire band, and
has a good vertical response as well as horizontal performance. One could actually use the
K5DDD antennas for both SSB and FM. The biggest limitation I have found when operating 2m SSB,
however, is electrical, especially power line, noise. Much of this noise is vertically
polarized. KB6KQ halos provide more "cross-polarization" isolation than anu other I have
used; the first time I put these antennas on my vehicle, the band was so quiet I thought I had
suffered a receiver malfunction in my 2M transceiver (embarrassing but true)!! This is why I
use the KB6KQ loops. When stacked, the KB6KQ Loops provide on the order of 4.5 to 5 dB,
(measured) gain over a dipole, depending on stacking distance (vertical separation).
All but the last picture below show how I have my KB6KQ Loop antennas mounted. The first is
a picture of my "upgraded" mobile (replaced a 1995 F-350 with a 2005 F-350 crewcab). The
antennas are labled. They are all mounted on a 3/4" plywood "bed cover" I built for my pickup
truck. The system can be raised and lowered with the hydraulic system, switched from inside
the cab, whether in motion or not. "Down" is for around town with all the trees hanging over
the road, and "up" is for out on the highways where vertical clearance is not a problem. The
6m Loop is 2' above the bottom 2m Loop. When down, the top 2m Loop is 16" above the 6m Loop
and 40" above the bottom 2m Loop. When up, the top 2m Loop is 2' above the 6m Loop and 4'
above the bottom 2m Loop (the full 5/8 wavelength spacing). Note height above ground given in
picture captions.
Note the Alford slot antennas for 1296 and 902MHz. These are bolted to the "bed cover" just
behind the crew cab, and provide about 6dBd horizontally polarized gain. These are
surprisingly effective antennas!
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Scroll down to see a detail of the 1296MHz Alford slot antenna.
An overview of the mobile antenna farm.
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Down - Top 2m Loop 9'6" above the road |
Midway |
Up - Top 2m Loop 12'6" above the road |
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The Alford slot antenna, made by W5OE as described
HERE, is mounted
on a 30" length of 1" black water pipe bolted to the "bed cover" just behind the driver's side
of the pickup crew cab (used a pipe flange mount). Extensive testing shows this antenna to
work quite well, even outperforming more costly multiple-bay antenna arrays.
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click below for more detail on the KB6KQ Loops
Norman W. Pedersen, KB6KQ
70 Arrowhead Dr
Carson City, NV 89706
360-423-4905 or kb6kq@pyramid.net
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