Notes on Assembly:
On the cable ends you do not need to use twin lead, I have made these antennas using
a single piece of 12 gauge copper wire for each end,, you can also use ladder line etc.
I would advise using heavy end wires for strength purposes.To prevent the joints from
breaking especially for long lengths, I picked up some 1/2 inch PVC pipe and end caps.
I cut the PVC so it would overlap a few inches on the joints. I then glued the end caps on.
Place the PVC between the joints and secure with regular screw hose clamps. Put the
clamps close to the end caps and it will give a strong joint. Do this for the center also.
About The Antenna
The Double Bazooka Dipole is a very efficient antenna which is very quiet,and does not
require the use of a balun. This antenna consists of coax(RG58) with the shield split
at the center and the feedline attached to the open ends. Do not break the center conductor.
With the feedline attached directly to the two open ends this acts as a half wave dipole
along with the open wire end sections.This antenna can be cut for any operating frequency
and is broad banded. It can be mounted as a flat top or an inverted vee and will handle the legal limit.
I recently built a 75m double bazooka using RG-213 cable with #6 end wires.
Here are the results, bandwidth increased to 300kc with the antenna center tuned
at 3.825 with a 1:2:1 SWR. On the low end 3.690 the SWR is 2:0.1 and the same at 4.0Mhz
using an MFJ antenna analyzer.
I gained about 75kc more bandwith using the heavier RG213 cable and end wires
vs RG58/U and #12 wire for the ends.
This antenna is heavy but using it as an inverted "V" with the apex at 35ft.
Where the cable ends connect to the end wires I used 1/2" PVC across these joints
and secured with worm clamps which removes the strain on the joints.
For the center I used a 1/2" 4 way PVC "T" using worm clamps to secure the cable.
On the top portion of the "T" I drilled a hole and use this as the anchor point to the push up pole..
The PVC sections coming out of the 4 way "T" are about 8" long.
The bottom portion of the "T" secures the RG-213 feedline with worm clamps taking the
strain off the center portion.
After the antenna was cut and tuned I sealed everything
with clear RTV
to prevent water from getting into the joints and running down the coax.
The antenna wire ends will be a little shorter when using the heavier cable and end wires.
as the initial matched center frequency was 3.5MHZ so had to do some trimming.
The internal antenna tuner on my Kenwood 480SAT will match the radio down to 3.5Mhz and
when using the SB-200 amp it does not seem to have any problems going into a 2 to 1 SWR.
For the higher bands (40m & up ) I use the RG-58u cable and will provide a good SWR.
Do not try and use one antenna for other bands as you will have a great loss as
they are efficent only for the band they were cut for.
I have one for each band going into a home brewed 9 position coaxial switch so no need
for an antenna tuner. This is great except for the amount of coax you need for the
all the cable runs into the shack.