Technical Library & Antenna Specs | Greyline Performance
The Signal Lab
The Greyline Standard: Technical Specifications
The engineering behind Smart, Strong, Elegant. This page covers VDA physics, wind ratings, feedline logic, and the 5/8λ advantage — the technical foundation behind every Greyline antenna.
16' Greyline DXF Flagpole Antenna — Hawaii. Curb appeal, HOA approved, full HF coverage.
The Physics
VDA: Why No Radials
Traditional quarter-wave verticals feed at the current maximum at the base — maximum I²R loss directly through soil. Every ohm of ground resistance sits in series with your radiation resistance, stealing signal before it leaves your yard. The standard solution is a buried radial field. On 160 meters, a proper radial field spans roughly 200 feet in every direction, running toward every noise source on the property line.
The Greyline VDA is a vertical dipole — an OCF (off-center fed) design with an elevated feedpoint. Return current flows through the lower element rather than through a buried radial field, significantly reducing ground coupling. The antenna does not rely on soil as part of its circuit.
No Radials
Return current flows through the lower element — not through a buried radial field. No ground system required.
160–6M Coverage
Continuous coverage across the amateur bands when paired with a quality ATU. One antenna, every HF band.
Any Surface
Concrete, asphalt, rooftop, frozen ground. Performance does not depend on soil conductivity.
Feedline & Tuner
ATU Placement: Base vs. Shack
Both locations work. Greyline operators run excellent signals from both configurations. The honest breakdown:
Remote at the Base — Preferred
Matches impedance at the feedpoint. The entire feedline run carries a matched 50Ω signal. Minimum loss. Recommended: LDG RT-100 — 100W, weatherproof, DC over coax.
Shack-Side — Common & Effective
Works well for most installations. Use LMR-400 minimum — larger diameter coax means less resistive loss. Every dB counts. Make the coax count too.
Power handling is not limited by the antenna — it handles the legal limit and beyond. Your power ceiling is the rating of your chosen ATU. See the RF Balance guide for full feedline and isolation details.
Structural Engineering
Wind Ratings — ASCE 7-10 by Height
6061-T6 aircraft-grade aluminum. Graduated wall construction — 0.125" lower 30%, 0.065" upper 70%. 2" OD, full length. Zero plastic. McMaster-Carr hardware throughout. Every wind rating is derived from ASCE 7-10 structural engineering values — not catalog estimates.
| Height | Wind Rating (Flag Down) | Best For |
|---|---|---|
| 12 ft | 155 MPH | High-wind sites, rooftops, tight lots, EmComm |
| 16 ft | 115 MPH | Compact suburban lot, front entry, rooftop EOC |
| 20 ft | 90 MPH | Most popular — balanced across all bands |
| 24 ft | 70 MPH | Serious DX, agency standard, larger lots |
| 28 ft | 55 MPH | Maximum low-band aperture, EOC permanent install, sheltered sites |
DXF flagpole models have separate flag-up ratings. Federal practice: lower the flag when weather threatens. See individual product pages for flag-up/flag-down specifications.
Performance
The 5/8λ Advantage
The 5/8λ point is peak gain for a vertical — beyond it, the pattern begins to rise. Each Greyline model is optimized for a specific band sweet spot. The 9' whip add-on shifts the sweet spot upward by the equivalent of 9 feet of additional aperture, delivering up to 3.5 dBi of low-angle gain on key DX bands.
20 ft
5/8λ on 10M
Most popular
24 ft
5/8λ on 12M
17M with 9' whip
28 ft
5/8λ on 15M
Flagship
Questions? Call 435-200-4902 or visit /pages/contact
Ham Radio is fun again. Pass it on. 73, The Greyline Performance Team