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Solar
SFI 147
SN 89
A 8
K 1 Quiet
X-Ray C1.0
Wind 399.5 km/s
Aurora 3
Updated 22:00 UTC HamQSL · N0NBH
Day 80/40m Fair 30/20m Good 17/15m Good 12/10m Fair
Night 80/40m Good 30/20m Good 17/15m Good 12/10m Poor

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Build a 17 Meter Vertical Antenna

The 17m quarter-wave vertical pairs the easy, compact build style of this family with a quiet, contest-free WARC band known for productive late-afternoon and early-evening DX. At just under 13 feet tall, it's a straightforward single-section build, and because the entire 17m allocation is only 100 kHz wide, a single well-tuned vertical covers the whole band with excellent SWR. This guide covers the complete build from element sizing through radial installation, feedpoint assembly, and final tuning for 18.1 MHz operation.

12.92 ftElement length (18.118 MHz)
~35–50 ΩFeedpoint impedance (with radials)
~14°Low-angle takeoff for DX
~$55Typical build cost

Quarter-Wave Vertical Fundamentals at 18.1 MHz

Quarter-wave element length: Length (ft) = 234 / f(MHz) At 18.118 MHz (17m band center — recommended): 234 / 18.118 = 12.92 ft (3.94 m) At 18.068 MHz (17m band bottom): 234 / 18.068 = 12.95 ft (3.95 m) At 18.100 MHz (FT8 calling frequency): 234 / 18.100 = 12.93 ft (3.94 m) At 18.168 MHz (17m band top): 234 / 18.168 = 12.88 ft (3.93 m) Starting length recommendation: Cut to 13.5 ft (4.11 m) — trim to resonance. Extra length costs nothing; too-short needs splicing.

A single 14-foot length of aluminum tubing handles the element with no telescoping required.

17m vs 12m Vertical — Key Differences

  • Element is slightly longer: 12.92 ft vs 12m's 9.38 ft — still a straightforward single-section build.
  • Radials are correspondingly longer: 17m radials are ~12.9 ft each.
  • Same narrow-band, no-contest character: like 12m and 30m, 17m is a 100 kHz-wide WARC band with no contest activity.
  • Often the best late-day DX band on this site: 17m frequently stays open into the late afternoon and early evening after 15m and 12m have started to close.

Radiation Pattern and DX Performance

17m vertical radiation pattern (good ground): Maximum radiation: ~14–18° elevation angle (low-angle — optimal for DX) Null: straight up (90°) 17m dipole at 20-25 ft (~0.4λ height at 18.118 MHz): Maximum radiation: ~30-35° elevation angle (moderate angle)

As with 15m, the 17m vertical offers a clear DX advantage for stations without a support taller than about 25 feet.

Element Construction Options

  • Single aluminum tubing section: a single 14-foot length of 0.75-inch OD 6061-T6 aluminum tubing handles the 12.92-foot element with no telescoping required.
  • Stainless steel whip: a longer ham-specific stainless whip (13–14 ft) works directly, trimmed to length.
  • Fishing pole with wire: a 4.2-meter (14-foot) fiberglass fishing pole with #18 AWG copper wire taped along the outside makes a lightweight, portable option.
Target frequency Band segment Element length (ft) Element length (m) Notes
18.068 MHzBand bottom12.95 ft3.95 mBottom of the 17m allocation
18.100 MHzFT8 / digital12.93 ft3.94 mFT8 calling frequency
18.110 MHzPhone begins12.92 ft3.94 mStart of the phone portion
18.118 MHzBand center (recommended)12.92 ft3.94 mBest all-around cut — covers the whole band
18.168 MHzBand top12.88 ft3.93 mUpper band edge

Vertical 17m Calculator

Materials for a ground-mounted 17m quarter-wave vertical with 16-radial ground plane

📏0.75-inch OD 6061-T6 aluminum tubing, 14 ftSingle section — no telescoping needed for the 12.92 ft element
🏗️Antenna base mount / ground spikeDX Engineering, Hustler, or homebrew PVC sleeve in concrete
🔩SO-239 chassis connector (feedpoint)Mounts at element base for coax connection
🌀RG-8X coax, length to reach radioLMR-400 preferred for runs over 75 ft
📡#14 AWG bare copper wire, 220 ftFor 16 radials at ~13.5 ft each
🔘Copper radial plate or bus bar, 1 pieceCentral hub connecting all radials and coax shield
🔩Stainless steel ring terminals, 20 piecesFor radial wire connections at hub
🔮FT-240-31 toroid for current chokeAt feedpoint — prevents coax shield from radiating
📡NanoVNAFor resonance measurement and full-band SWR sweep
🪛Soldering iron, rosin core solder, self-amalgamating tapeFor feedpoint connections and weatherproofing
🔧Hacksaw or tubing cutter, fileFor cutting aluminum tubing to final trimmed length
🔩Noalox anti-oxidant compoundFor element base connection to feedpoint bracket

What the NanoVNA Will Show

Expected feedpoint impedance vs radial system: Perfect ground (theoretical): ~36 Ω 4 on-ground radials: ~55 Ω 8 on-ground radials: ~46 Ω 16 on-ground radials: ~41 Ω 4 elevated radials (λ/4 = 12.92 ft high): ~35 Ω 17m-specific note: As on 12m, the whole allocation is only 100 kHz wide. A vertical tuned to the band center shows almost flat SWR across the whole band.

Rooftop and Portable Installation Considerations

  • Use elevated radials: 4 elevated radials at λ/4 length (12.92 ft) perform nearly as well as a full on-ground system.
  • Metal roof interaction: keep the element base at least 2–3 feet above metal roofing.
  • Wind load: a 14-foot 0.75-inch aluminum element is light enough for a simple mount with light guying.
Finished 17m quarter-wave vertical antenna — aluminum tubing element on a base mount with 16 ground radials and SO-239 feedpoint connector

Building the 17m Quarter-Wave Vertical

This guide builds a ground-mounted single-section aluminum tubing vertical with a 16-radial on-ground system.

1

Select the Site and Plan Radial Layout

Choose a site with at least 14 feet of clear ground in all directions. Keep the element clear of metal structures within 5–8 feet, and route the coax to exit the feedpoint at 90°.

2

Cut the Aluminum Tubing Element

Cut the 0.75-inch OD aluminum tubing to 13.5 feet (162 inches) — longer than needed for trimming. Deburr both ends.

Initial cut: 13.5 ft (162 inches) Target after trimming: ~12.92 ft (155.0 inches) at 18.118 MHz Trim allowance: ~7 inches Trim rate: ~1 inch = ~45-50 kHz shift upward Trim conservatively in 1-inch increments.
3

Install the Base Mount and Feedpoint Assembly

Install a lightweight base mount. Mount the SO-239 with the center pin to the element and shell to the radial hub.

Insulate the element base from earth: Verify electrical isolation from ground with a multimeter.
4

Install the Radial Hub and Run 16 Radials

Cut 16 radials of #14 AWG copper at 13.5 feet each, bolt them to the hub at 22.5° intervals, and stake flat to the ground.

5

Raise the Element and Connect Coax

Slide the element into the base mount. Connect the coax, install a current choke (6–7 turns of coax through an FT-240-31 toroid), and weatherproof the connection.

6

Initial SWR Measurement

Sweep 17.0–19.0 MHz with the NanoVNA.

Expected initial readings (13.5 ft element): SWR minimum location: ~17.3 – 17.5 MHz (element cut long — resonance is below target) SWR at minimum: 1.2 – 2.0:1
7

Trim to Resonance

Trim calculation: ΔL = L_now × (1 − f_now / f_target) Example: f_now = 17.40 MHz f_target = 18.118 MHz L_now = 162 inches (13.5 ft) ΔL = 162 × (1 − 17.40/18.118) = 162 × 0.0396 = 6.4 inches Trim in 1-inch increments. Re-raise and re-measure after every trim.
8

Verify Full Band SWR and Document

Typical 17m vertical SWR sweep results (tuned to 18.118 MHz, 16 on-ground radials): 18.068 MHz: ~1.2:1 18.118 MHz: ~1.1:1 ← resonance 18.168 MHz: ~1.2:1

Weatherproof all connections and bond a ground rod at the base to the radial hub.

4 Elevated Radials for Rooftop Installation

The 17m vertical fits on most residential rooftops with a simple tripod mount, using 4 elevated radials at 12.9 ft each.

Portable 17m Vertical — Field Deployment

A 4.2-meter fiberglass fishing pole with #18 AWG wire, paired with 4 short ground radials, makes an effective field vertical — and 17m's late-afternoon DX window is a great match for a typical POTA activation schedule.

Symptom Most likely cause Diagnosis Fix
No SWR dip visible across 17–19 MHzFeedpoint connection fault or coax polarity reversedCheck DC resistance from coax center to shieldVerify center pin to element, shield to radial hub
SWR minimum broad or highToo few radialsCount radial connections at the hubAdd radials toward 16
Resonance below 18.068 MHzElement too longMeasure element lengthTrim — 1 inch raises resonance ~45-50 kHz
Resonance above 18.168 MHzElement too shortMeasure element lengthSplice a short extension onto the tip
SWR correct but noisy receiveNo current chokeCheck for RF on the coax outer near the radioInstall an FT-240-31 current choke at the feedpoint
Band seems dead middayNormal propagation lull for 17mCheck propagation reports for time of dayNot a fault — try late afternoon/early evening, 17m's typical strong window

Why is 17m only 100 kHz wide?

17m is a WARC band allocated in 1979 as a narrow, non-contest slice, like 12m and 30m.

Is 17m good for DX?

Yes, especially in the late afternoon and early evening — a favorite window when 15m and 12m have started to close but 20m is still crowded.

How many radials do I need?

More is better, with the biggest gains in the first 8; 16 is easy at this radial length.

Why doesn't 17m have contests?

Like the other WARC bands, it was set aside without contest activity when allocated in 1979.

Can I mount this on my roof?

Yes, with 4 elevated radials — an easy installation.

How does 17m compare to 12m for propagation?

17m is somewhat less solar-cycle dependent and tends to stay usable more consistently than 12m or 10m.


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