Hex Beam Antenna – Center Post & Accessories

Overview

The Hex Beam is a type of directional antenna.
Despite its appearance, assembly can actually be quite straightforward—except for the center post, which carries the signal to the radiating elements of the antenna.

Because the elements for each band are vertically separated, it’s best to use coaxial cable between each band. This, however, introduces a waterproofing challenge:
Water ingress into coax will cause signal loss over time.

Professionally made solutions often use precision-machined tubes with an inner conductor, essentially creating a coaxial transmission line with isolated taps at specific heights. While effective, this approach can be complex for DIY builds.
A simpler approach for home projects is to place connectors outside the center post.

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My Approach

3D printing offers a waterproof, easy-to-assemble, and inexpensive solution.

Band Spreader V1

• Used coax pieces covered in silicone on the outside.
• Worked for over a year but was messy and didn’t inspire confidence.

Band Spreader V2

• Two-piece design:
  • One coax cable from the bottom part.
  • One coax cable from the upper part.
• Inside, the coax cables split to two bolts.
• Wire elements attach to the bolts with M4 lugs.
• Before sliding the bottom part into the upper part, pour silicone inside for waterproofing.

⚠ Note: This version has not yet been tested, but it should be more robust, watertight, and still inexpensive.

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Rod Adapters

My Hex Beam uses fishing rods for its arms.
Rods are mounted to the base plate using rod adapters.

• After printing, remove the tiny vertical pieces in the horizontal split (embedded supports) with clippers.
• Adapters work as clamps—use M6 U-bolts to secure them after inserting the fishing rod.
• Two adapter types:
  • Standard size.
  • Slightly larger inner diameter for the rod base.
• You’ll need two adapters per side.
  I have noticed that these cheap rods have wide spread of tolerances when it comes to diameter of elements, that is why adapters are used as a clamps that adapt the more precise U bolts to slightly varying bases of the rods.

For my antenna, I initially used dimensions for the reflectors and radiators from the Hex Beam drawing by YI1QEA (easy to find online).

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Additional Parts

Ground Support Element

• Supports a grounding wire connecting each reflector.
• Grounding is recommended during lightning storms to lower the risk of high potential build-up.
• I run an orthogonal cable between each reflector and solder it in the middle.
• Two ground supports in a cross configuration (zip-tied) keep soldered wires stable and prevent fatigue over time.

Wire Isolator

• Used to adjust tension between wires and ropes.

Guy Rope Elements

• Attach guy ropes to the center post.

Top Cap

• Covers the 16×16 mm profile at the top to prevent water ingress.

Balun Adapter

• Used to attach a PVC electrical box containing the balun.

HexBeam 500

• Includes 3D models showing how the center post is assembled.

Isolator HV

• Increases creepage voltage at the balun output.

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Parts List (Non-Printed)

• 6 × 6 m fishing rods
• 380 × 380 mm aluminum plate (≥ 4 mm thick recommended)
• 16×16×1500 mm aluminum profile
• 12 × M6 U-bolts (55×34 mm)
• M5 and M4 screws and bolts (plus M4 lugs)
• UV-resistant rope
• Balun (recommend FT240-43 toroid)
• RF connector of your choice

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Notes

• For permanent installations, use UV- and high-temperature-resistant materials (e.g., ABS or ASA filaments).
• This project is marked as Work in Progress because Band Spreader V2 has not yet been tested.