I needed a multiplier beam for the Southeast for working Caribbean multipliers. At best far away from my main tower. However the best spot was full of trees shedding branches, and a regular tower would be risky. I remembered constructing a 3 el 20m Spiderbeam using a carbon glass fishing rods. It was lightweight and survived many months until I got the regular 5 band model. The fishing rod design was very light. I used a 30ft aluminum mast weighing abut 20 lb. For a multiband setup, a Spiderbeam design would be too heavy for the fishing rods.
Here is the design for new beam.
1. Square 2 el design that is compact.
2. Lightweight carbon fiber mast from Gigaparts
3. Spreader from an aluminum angle
4. Carbon fiber fishing rods, originally 20ft but smallest elements removed
5. 20 gauge magnet wires (0.8mm).
6. Balun by coiling the coax around a ferrite
7. Mast attached to a garden post.
8. Guy wires are thin Dacron ropes attached to a dog spiral posts.
20-15-10 elements were connected together. First I tuned reflectors for maximum F/B at the right frequency. Then driven elements for the lowest SWR. Since the carbon fiber is conductive, the elements were suspended from the poles by plastic clips.
The whole setup weighs about 10 lb, and I can raise and lower the antenna in 10 seconds.
How does it work? Much better than a vertical or a dipole. Almost as good as Spiderbeam, my other multiplier antenna. Sometimes better than my phased beams as the required takeoff angle to the Caribbeans is pretty high.
There was one failure when 10-15m stopped working. The plastic spreaders melted as thin wires heated during 48h contesting at 1.5 kW.
This antenna was setup in October 2023 and it is still standing in February 2024. Probably it would not withstand ice or snow loading but winds are no problem.
For extra details, see a post in the antenna group at groups.io.
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