A coax atenna project by WB4CPO from the late 80s that can be considered a double bazooka antenna.
Type of coax needed — RC 58/U or RC 8/U. RC 58/U is the best.
Use the same type coax for antenna and feed line.
Maxium legal power can be used on the RG 58/U without fear of feed line breakdown.
80 meter example:
Start with 128 ft of coax and make center reference point. Measure from center reference point out each way for a distance of 30 ft 6 in. Solder the inner conductor to the shield at both points. This forms the 52 ohm matching balun. Waterproof both joints well. Next, at both ends of the antenna, short the center conductor to the shield but do not waterproof until after trimming for tuning purposes.
At the center reference point, remove one inch of the vinyl jacket (1/2 in each side of center).
Cut the shield in the center all the way around the coax.
DO NOT CUT THE INSULATION OR CENTER CONDUCTED.
Connect the feed line to the shield leads, one shield lead to the center conductor of the feed line and the other shield lead to the shield of the feed line.
Waterproof well and mount on a 4 in x 4 in piece of plexiglass to hang from outrigger up on tower.
For 75-80 meters the feed line lengths should be 57 ft, 87 ft, or 103 ft.
Separate feed lines must be used for each band.
In summary, the advantages of this antenna are:
- Broad bandwidth: Unaffected by environment
- Positive gain over a common dipole
- Greatly attenuate harmonics
- Decreases static charge build-up
- Essentially non-directional
