Mounting a 31m Doublet on a 10m Pole with 16m 600Ω open-wire feedline

Antenna Type: Doublet (2×15.5m legs, 31m total span)
Center Support Height: 10 meters (carbon mast)
Feedline: 16 meters of 600Ω open-wire feedline
Recommended Configuration: Inverted-V

Inverted-V Geometry

  • Feedpoint height: 10m (top of center carbon mast)
  • End height: Ideally between 2 to 4 meters above ground
  • Leg angle (apex angle):
    • Optimal: 120°–140° between the legs (60°–70° from vertical per leg)
    • Minimum recommended: 90° (anything tighter reduces efficiency and bandwidth)
    • Optional 10m rope extension available: Helps achieve the ideal leg angle, anchoring is on ground level.

Open-wire Routing

  • First 2–3 meters: Drop vertically from feedpoint to reduce imbalance
  • After vertical drop: Gentle curve or slope toward tuner location
  • Keep open-wire:
    • At least 10–15 cm from any conductive surface
    • Away from metal poles, gutters, fences, or walls
    • Free-hanging or on non-metallic standoffs if necessary

End Anchoring

  • Anchor distance: ~15.5m out from the base of the center pole
  • Use: Non-conductive rope, UV-resistant if outdoors
  • Anchoring point height: The higher, the better (2m or more is fine)
  • Optional 10m rope extension available: Helps achieve the ideal leg angle, anchoring is on ground level.

Performance Notes

  • Radiation pattern: Broadside, omnidirectional lobes on higher bands
  • Usable bands: 160m (less efficient, but workable with Z-match), 80m to 10m (efficient with tuner)
  • Tuner location options:
    • Best: 1:1 current balun + remote tuner at open-wire transition
    • Alternative: 1:1 balun + indoor tuner (coax feedline can lead to higher losses !)

A remote tuner at the base of the open-wire is highly recommended to ensure the best performance and lowest loss on all bands. (read more)

Alternatives

If space and budget allow for two extra 10m poles:

  • Consider a flat-top horizontal doublet for better 80m NVIS and consistent multi-band performance
  • Maintain 16m center height, horizontal legs, and vertical open-wire drop

This configuration offers an excellent balance between ease of installation, low-angle and high-angle radiation, and good all-band performance using a 600Ω open-wire feed.

Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.