KL7JR Vertical
Pancake Dipole 10-20 Meters
I was
amazed when I first learned of the TAK-tenna reduced size dipole on Hamuniverse.com. I immediately was
inspired to homebrew the design but for vertical use.
Sometime about a
year a go I contacted Steve, WA2TAK, to see if he experimented with his
design as a vertical dipole. His answer was "no", but now Im seeing
references on the internet where some hams are trying it vertically with
good results.
After a trip to Home Depot, heres my version of the
design by WA2TAK (*which appears similar to K6NOs spiral tuning coil type
antenna. See footnote
below).
I
originally was going to use a PVC backbone, and then I thought about using
plastic lattice until I saw the plastic diffuser sheets used for some
fluorescent lights.
See pictures
below.
I purchased a
sheet 18 inches wide by 36 inches long. I cut out two pieces (one per leg
of the dipole using side cutter pliers) 23 inches by 15 inches. It is not
recommended for outdoor use as this material is too fragile..oh did I
mention I was going to use this as an indoor antenna in a limited space
situation (landlord says no exterior antennas), in my four foot high
window and go QRP maybe to avoid problems with my neighbors? What a
challenge, eh?
Saving grace, is that my apartment is on the 14th
floor of a high-rise , so the added height above ground may be that little
extra help I need on this design.
My living room window sill
was about 12 inches wide, so the antenna had to be a rectangular loop of
wire to better fit vs. the round popular style, and the boom is made from
3/4 inch PVC pipe (40 inches long).
I used #16
stranded insulated wire. Each leg was about 20 feet long which should
yield 10-20m for sure, and just maybe 40 meters if the antenna works at
all.
When the dust settled, I had about $30 invested in this design
and it took about 3 hours to build.
The antenna easily
loaded 10-20 meters in the vertical configuration but it didnt do well for
me on 10 and 17 meters as a horizontal dipole. With this in mind, I
concentrated on the antenna for vertical use. Your particular set up may
show the opposite results. On a mid March weekend (2009) under more poor
band conditions, I heard two stations on 20 meters and worked them both.
An Oregon ham and I exchanged 5x9 reports, and in California I received a
5x4 report and gave a 5x7. My power level was 50 watts.
I forgot to try it on 40m but since it easily
loaded on 20, Im thinking 40 is possible as well. Im pleased enough with
this design to further experiment as an indoor vertical using "long coils"
as I did with my 10-40 meter
vertical dipole using 102 inch steel whips.
This would no doubt make a good antenna design should you have the luxury
of being able to mount it outdoors and perhaps tweak it a
bit!
Have fun antenna
experimenting. 73 de Yukon John, KL7JR
Antenna resting high
above the Alaska snow!
(That's a 12lb "dirty" snow ball holding it
down)
Same antenna, same snow,
horizontal position....warming from the cold!
Foot
note:
