Build a 30 Meter Vertical Antenna
The 30m quarter-wave vertical brings this family's low-angle DX performance to the quiet, CW/data-only WARC band favored by digital-mode and CW operators. At just over 23 feet, the element is a two-section telescoping build — taller than the 20m/12m/17m verticals but noticeably shorter than the 40m version. This guide covers the complete build from element sizing through radial installation, feedpoint assembly, and final tuning for 10.1 MHz operation, along with the reduced-power, CW/data-only rule that governs this band.
Quarter-Wave Vertical Fundamentals at 10.1 MHz
At 23 feet, this element sits between the single-section builds used for 10m–17m and the fully telescoping 40m design — a two-section telescoping build is the practical sweet spot here.
30m vs 40m Vertical — Key Differences
- Element is noticeably shorter: 23.11 ft vs 40m's 32.7 ft — a two-section telescoping build rather than three.
- Radials are correspondingly shorter: 30m radials are ~23 ft each, using meaningfully less copper than the 40m system.
- No phone, reduced power: 30m is CW/data-only at 200W PEP maximum — see the callout above.
- No contests: like 12m and 17m, 30m is a WARC band with no contest activity.
- Round-the-clock usability: 30m behaves more like 40m than the higher HF bands, supporting daytime regional contacts and nighttime DX.
Radiation Pattern and DX Performance
As on 40m, the 30m vertical offers a clear DX advantage over a dipole at typical suburban heights, while a low dipole better serves regional/NVIS-style coverage.
Element Construction Options
- Two-section telescoping aluminum: a 1.0-inch OD lower section (12 ft) telescoping into a 0.75-inch OD upper section (12 ft), overlapped 6 inches, gives the 23-foot working length. Self-supporting in moderate wind.
- Fiberglass fishing pole with wire: a 7-meter (23-foot) telescoping fishing pole with #18 or #14 AWG copper wire taped along the outside — portable and quick to deploy.
- Wire on a rope or existing support: a wire hanging from a tree branch or mast at least 24 feet tall, pulled taut with a weight at the bottom.
| Target frequency | Band segment | Element length (ft) | Element length (m) | Notes |
|---|---|---|---|---|
| 10.100 MHz | Band bottom / CW | 23.17 ft | 7.06 m | Cut here for CW-only operation |
| 10.125 MHz | Band center (recommended) | 23.11 ft | 7.04 m | Best all-around cut |
| 10.136 MHz | FT8 / digital | 23.08 ft | 7.03 m | FT8 calling frequency |
| 10.150 MHz | Band top | 23.05 ft | 7.03 m | Upper band edge |
Vertical 30m Calculator
Materials for a ground-mounted 30m quarter-wave vertical with 16-radial ground plane
What the NanoVNA Will Show
Rooftop and Ground-Mount Considerations
- Use elevated radials: 4 elevated radials at λ/4 length (23.11 ft) perform nearly as well as a full on-ground system, though the longer radial length makes ground-mounting more practical here than on the shorter-band verticals.
- Metal roof interaction: keep the element base at least 3 feet above metal roofing if mounted elevated.
- Wind load: a 24-foot two-section aluminum element has more wind load than the shorter verticals in this family — a solid base mount with guying is recommended in exposed locations.
Building the 30m Quarter-Wave Vertical
This guide builds a ground-mounted two-section telescoping aluminum vertical with a 16-radial on-ground system.
Select the Site and Plan Radial Layout
Choose a site with at least 24 feet of clear ground in all directions. Keep the element clear of metal structures within 8–10 feet, and route the coax to exit the feedpoint at 90° for the first 10–15 feet.
Cut and Prepare the Aluminum Tubing Sections
Cut both aluminum sections to length with a hacksaw or tubing cutter and deburr all cut ends.
Drill a 3/16-inch hole through both walls at the joint overlap midpoint for a locking bolt, and apply Noalox anti-oxidant compound before assembly.
Install the Base Mount and Feedpoint Assembly
Install a base mount — a commercial ground spike mount or a PVC sleeve set in concrete, at least 18 inches deep, supports this element well. Mount the SO-239 with the center pin to the element and shell to the radial hub.
Install the Radial Hub and Run 16 Radials
Cut 16 radials of #14 AWG copper at 24 feet each, bolt them to the hub at 22.5° intervals, and stake flat to the ground every 6 feet.
Raise the Element and Connect Coax
Assemble the telescoping sections, slide the element into the base mount, and secure it. Connect the coax, install a current choke (7 turns of coax through an FT-240-31 toroid), and weatherproof the connection.
Initial SWR Measurement
Sweep 9.7–10.5 MHz with the NanoVNA.
Trim to Resonance
Verify Full Band SWR and Document
Weatherproof all connections and install a ground rod bonded to the radial hub for lightning protection. Set your radio's power limit to 200W or below and confirm you're operating CW or a data mode.
4 Elevated Radials as an Alternative
Where ground space is limited, 4 elevated radials at 23.11 ft each, mounted at least a few feet above ground, perform nearly as well as a full on-ground system.
Why This Band Is CW/Data-Only
30m is shared internationally with non-amateur fixed and mobile services, which is why most administrations — including the US — restrict amateur use to narrowband CW and data modes and cap output power well below what's permitted on adjacent bands. Building this vertical for phone operation is not an option on 30m; plan your operating around CW and digital modes from the outset.
| Symptom | Most likely cause | Diagnosis | Fix |
|---|---|---|---|
| No SWR dip visible across 9.7–10.5 MHz | Feedpoint connection fault or coax polarity reversed | Check DC resistance from coax center to shield | Verify center pin to element, shield to radial hub |
| SWR minimum broad or high | Too few radials | Count radial connections at the hub | Add radials toward 16 |
| Resonance below 10.100 MHz | Element too long | Measure element length | Trim from the top section |
| Resonance above 10.150 MHz | Element too short | Measure element length | Splice a short extension onto the tip |
| Telescoping joint loosens over time | Hose clamps not tight enough, or missing locking bolt | Check joint tightness periodically | Re-tighten clamps; add the locking bolt if not already installed |
| Radio won't allow SSB/phone on this band | Not a fault — correct behavior | Check the radio's band-plan lockout settings | Operate CW or a data mode; phone isn't permitted on 30m |
Can I operate SSB phone on this antenna?
No — 30m is restricted to CW and data modes only in the US and most other countries.
Why is the power limit only 200W?
30m is shared internationally with non-amateur services, so US rules cap all license classes at 200W PEP on this band.
How many radials do I need?
More is better, with the biggest gains in the first 8. A full 16-radial system uses meaningfully less wire than the 40m version given the shorter radial length.
How does 30m propagation compare to 40m?
Very similar — solid daytime regional coverage with DX openings at night, and often somewhat less atmospheric noise than 40m.
Do I need the two-section telescoping design, or can I use a single tube?
A single 24-foot aluminum tube is heavier and harder to source than a two-section telescoping design, though it's mechanically viable if you can find suitable stock. The two-section approach is the more practical default.
Why doesn't 30m have contests either?
Like 12m and 17m, 30m was set aside without contest activity when allocated in 1979.