The Stick VHF Vertical Bazooka
A 2 meter /
Marine RG-6 Coax Version of the Vertical
Article by DE
I have produced the stick
antenna for hams and commercially by SKYLANE Products for 2 meters and
Marine VHF band since 1982. They are usually made from RG-58 coax and
housed in a white PVC housing for weather protection. The drawing
above is courtesy of VE3VDC from his article: 2 meter Vertical Bazooka
These antennas come from the same sleeve dipole family as
the famous Shakespeare Big Stick that gained enormous popularity with CBers and is
stillwidely in use by Marine Radio operators.
Hams have also produced many variations on the theme like the ones
W7LPN, N1GYand VE3VDC, all versions
of the Vertical Bazooka
design made from coax
andother materials. I have
also made versions of this antenna for 6 and 10
There is much to recommend this design but I will
not discuss the basic design here as it has been covered many other
places. The design has been proven beneficial for hams even with many
variations in materials. This is the core of Amateur Radio; to experiment,
build your own and learn aboutantennas.
I believe there is one basic error in
the design information presented by these authors. This may be a
misunderstanding of coax. When they refer to the velocity factor (VF) to
multiply the lower section, they only used RG-58 or RG-8 coax and referred
to the velocity factor of the coax used.However if you use RG-6 or other foam dielectric coax with a
VF of approximately .80, you will be too
VF they should have referenced is not the VF of the center conductor
insulation dielectric but the VF of the outside jacket of the coax. That
is the insulation that interacts with the outer sleeve. Fortunately, I
discovered that on RG-58 and RG-6 this VF is about .66. So that is the
shortening factor to use for polyethylene insulated coaxial cable outer
found a need while in Ecuador by cruisers wanting a standby VHF Marine
antenna in case their main antenna failed or was damaged. Also many
are also hams and wanted dual use as 2 meter and marine
In Ecuador the only coax readily available was RG-6 TV coax
cable. This posed several problems. The shield was aluminum wire and does
not readily accept solder. The braid is loose, with about 40 to 60 percent
coverage, over an aluminum foil. Thus making the sleeve was a problem.
There were no PL 259 style connectors for RG-6
How To Build The VHF Coaxial Sleeve
Recalling the many commercial antennas I had made using
copper tubing as the sleeve, I decided to use aluminum foil for the sleeve
and eliminate the dissimilar metals and the need to solder the
13-foot (4 meters) length of RG-6 coax was prepared by first removing
about 24 inches of the black outer covering. Be careful to not cut the
braid or foil removing the covering. I found a Xacto knife or sharp razor
blade would cut a clean groove down the length of the jacket and around
the circumference. The jacket peeled off
and removed all but 6 inches of the braid and foil. I then cut a 14-inch
strip of aluminum foil 3 inches wide. This strip was placed with the
14-inch length along the coax. This was wrapped around the outer jacket
below where the jacket was removed and rolled around until the whole
length was tightly wrapped. I used black plastic tape to secure the foil
tightly every 4 inches, not a critical dimension, beginning 2 inches below
the top end and leaving a few inches at the bottom for
applied a small amount of anti-oxide compound to the top 2-inch bare
aluminum foil. Then I doubled the braid back over the coax and aluminum
foil and pressed it tightly against the foil. The coax foil shield was
then folded down similarly along the foil. Using about a 4 inch wide by 4
inch long piece of aluminum foil, I wrapped this over the braid and foil
of the coax that was folded over. This wrap should be as tight as
possible. This made a good electrical connection between the coax braid,
foil and the aluminum foil along the coax. Tape the foil at the top
tightly to secure it.
I bent the top of the coax center conductor back on itself
so it could be used as a hanger for testing. I hung the assembly on the
side of a 5-foot piece of 3/4 inch PVC and prepared the far end of the
coax for connection to the wattmeter and
Connecting the RG-6 to a
There are several choices available for the connector to
the radio. The PL259 with adapter for RG-59 coax and type "F" TV cable
connectors are the most used types. I'll discuss these
that the PL259 connector with the adapter for RG-59 coax would fit well on
the RG-6. So one antenna was made this way by stripping the coax normally
after installing the adapter on the end of the coax. The foil and braid
was folded back on the adapter shell and trimmed at the
The center wire insulation was removed and the
connector body installed.The
adaptor was screwed into the body tightly and the center wire soldered to
the center pin. These adapters were designed for use without soldering.
Despite several articles about soldering the braid to the adapter, they
work well without soldering. I usually apply black tape over the cable and
adapter for strain relief.
Type "F" connectors are readily available and
work well up through 450 MHz up to 500 watts. In the USA and several other
countries there are adapters available for type "F" to PL 259. This is
perhaps the easiest connection to make on the RG-6
there were no PL259 connectors or adapters available in this part of
Ecuador, I used the type "F" on the coax. I prepared a 6 inch length of
RG-6 by putting a type "F" connector on one end and stripping the other
end about 3 inches. After stripping the insulation from the center wire,
solder a brass screw that fits securely in the SO239 radio connector to
the coax center wire. This is wrapped with black electrical tape for
insulation. The braid was twisted and wrapped around the outside of the
radio connector and secured by an adjustable cable clamp around the
connector shell. Then using a double female barrel splice, the two "F"
connectors were connected. This worked very well at 2 meters and VHF
testing, I made adapters from a couple PL259 connectors with about 6-inch
lengths of RG 6 coax installed and an "F" connector on the other end of
the coax. With 2 barrel connectors I could attach the antenna coax to the
wattmeter and the wattmeter to the radio.
Set PVC pole and antenna in the clear, away
from metal and set the transmitter to 146 mHz for 2 meters, 156mhz for
Marine, or a compromise of 148 or 149 for dual band use. Adjust the
antenna by clipping 1/2 inch at a time off the center conductor wire. I
was able to get 1.2:1 SWR with a 22-inch length at 146 mHz. This length
also was 2.5:1 at 156.475, Channel 69.
A second antenna was built and adjusted for
lowest SWR at 149 mHz and showed less than 2:1 SWR at 145 and 156 mHz.
This was considered adequate for dual band use. With 25 watts forward and
2 watts reflected, most any 2 meter or VHF marine radio will perform
adjustment the foil on the antenna lower section was over wrapped tightly
with black electrical tape.
The Antenna Housing
If wrapped tightly the antenna will fit
snugly into a length of 1/2 inch PVC. I considered this too tight for
general use, but it makes a lighter antenna for backpacking or emergency
used 3/4 inch PVC 5 feet long. At the upper end I cut a notch in opposite
sides to fit a piece of bamboo skewer. The end of the antenna is folded
over about 1 inch and hangs on this bamboo.
Cut the bamboo flush with the PVC and secure
it and the antenna with a bit of hot glue or
Cap the end
of the PVC with a pipe cap, which has a hole drilled in the top center. A
screw eye is screwed into this hole and sealed with RTV inside and out.
The eye can be used to haul the antenna up into a tree or up a mast.
Secure the cap on the PVC pipe with RTV.
At the bottom of the PVC pipe fit another cap
with a hole drilled in the center to pass the coax. It is a good idea to
put the cap on the coax before you install the connector. Again secure the
cap and around the coax with RTV.
This completes the assembly of the antenna. I
usually use two adjustable hose clamps, about 6 inches apart, to secure
the PVC mast to a support. Plastic tie wraps or tape can secure he coax
feet (15 meters) of RG-6 or RG-8 makes a good feed line. Since RG-6 is all
that is available here, I apply a type "F" connector on both ends of the
50-foot coax. A double female at each end allows connection to the antenna
and radio with the adapter as described above or a "F" to PL259 adapter.
For weather protection, wrap the coax fittings with black electrical tape
For a fixed station a variation that may improve
performance is to cut the PVC so it ends a few inches below the lower
sleeve shield end. Install a plastic Tee fitting and install the left over
PVC as a lower support. The coax should exit through the Tee fitting and a
short pipe stub. The PVC cap fits on this
coax should be wrapped about 8 turns around the support pipe to form a
current choke. Tape the coil and the feed line then drops down. Some
builders report this improves the radiation at a lower take off angle and
helps prevent feed line radiation. I have not tried the coax coil as I
have not found it to be a problem.
The antenna can be made as a roll-up
emergency antenna by not putting it is a housing. A loop in the top of the
radiator will allow tying a string or nylon cord to hang it up or pull it
into a tree. It can be taped to a window or to a bamboo or fiber fishing
pole. Use your imagination.
Enjoy your Sleeve dipole
This article shows
ham ingenuity at it's best. As mentioned in the article, many ham radio
connectors that we see as very common every day items are almost
impossible to get cheaply when you are in another country. The author
shows how we can overcome almost any "problem" when we use our brains!
Questions? Email here:
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