Build a 2-Meter Yagi Antenna
A homebrew 2-meter Yagi opens the full performance potential of VHF amateur radio — weak-signal SSB and CW contacts over hundreds of miles, satellite operation, meteor scatter, moon bounce (EME), and competitive VHF contest operation. At 144 MHz, a Yagi is compact enough to build from aluminum rods and a length of tubing at a cost under $40, yet it delivers 10–15 dBd of forward gain from a 6-element design that fits in a car. This guide builds a 6-element 144 MHz Yagi optimised for weak-signal and contest operation, using a simple folded dipole driven element for a clean 50 Ω feedpoint with no matching adjustments required.
Why VHF Construction Is More Demanding
Building a Yagi for 144 MHz requires more precision than building one for 14 MHz. At VHF, wavelength is 2 meters rather than 20 meters — every dimension is 10 times smaller and errors that were inconsequential at HF become significant at VHF:
Element Diameter Effects at VHF
Element diameter has a more significant effect on element length at VHF than at HF, because the diameter-to-wavelength ratio is larger at 144 MHz:
Boom Effect on Element Length
At VHF, the conductive boom affects the resonant frequency of elements mounted through it — this is the "boom correction" that VHF Yagi designers must account for. Elements passing through a metallic boom are effectively shortened electrically:
Coax and Feedline Considerations at 144 MHz
At 144 MHz, feedline loss becomes a primary design consideration that is essentially irrelevant at HF for short runs:
| Element | Function | Length (mm) | Length (inches) | Position from reflector (mm) | Position from reflector (inches) |
|---|---|---|---|---|---|
| Element 1 | Reflector | 1040 mm | 40.9 in | 0 mm | 0 in |
| Element 2 | Driven element | 965 mm | 38.0 in | 375 mm | 14.8 in |
| Element 3 | Director 1 | 935 mm | 36.8 in | 750 mm | 29.5 in |
| Element 4 | Director 2 | 922 mm | 36.3 in | 1175 mm | 46.3 in |
| Element 5 | Director 3 | 910 mm | 35.8 in | 1635 mm | 64.4 in |
| Element 6 | Director 4 | 903 mm | 35.6 in | 2115 mm | 83.3 in |
| Total boom length | 2115 mm | 83.3 in (6.94 ft) | |||
Materials for a 6-element 144 MHz Yagi with folded dipole driven element
Why Use a Folded Dipole
The folded dipole is the preferred driven element for a 2m Yagi for the same reasons it works well on HF — it multiplies the feedpoint impedance by approximately 4×, bringing the inherently low Yagi feedpoint impedance (25–35 Ω with parasitic elements) up to approximately 100–140 Ω, which a 2:1 balun transforms to 50 Ω. At 144 MHz this impedance transformation happens naturally with no adjustable components:
Simple Coax Folded Dipole for 144 MHz
The simplest homebrew folded dipole driven element at 144 MHz uses a short length of coax with the outer jacket and braid forming the return conductor:
Building the 6-Element 2m Yagi
Precision is the key to VHF Yagi performance. Measure every element twice before cutting. Use a steel rule, not a flexible tape. Cut with a fine-toothed saw in a miter box for clean square ends. File all cut ends smooth. Work in mm throughout — the dimension table is in mm for a reason.
Prepare the Boom
Cut the 1-inch OD aluminum boom to 2150 mm (84.6 inches) — 35 mm longer than the last element position to provide support beyond the final director. Mark all six element positions along the boom using a steel rule and a marking pen. Measure from one end (the reflector end) and mark each position from the table:
Cut All Elements to Exact Length
Cut all six elements from 3/16-inch aluminum rod. Precision here is the single most important step in the build:
Prepare Element Mounting Insulators
Cut six HDPE or Delrin insulating strips — one per element. Each strip should be approximately 25 mm wide, 8 mm thick, and 40 mm long. Drill a hole through the center of each strip sized for the element rod (3/16-inch, 4.76 mm). Drill two smaller holes through the strip for the U-bolt legs that clamp the assembly to the boom.
The element rod passes through the center hole of the insulating strip. The insulating strip sits on top of the boom. U-bolt legs pass through the outer holes in the strip and down around the boom, with the U-bolt bridge pressing on the element rod above. The insulating strip prevents the element from contacting the boom metal.
Build the Folded Dipole Driven Element
Build the coax folded dipole as described in the design section. This element is the only one connected to the feedline — all others are parasitic. Take extra care with the folded dipole construction:
- Cut 975 mm of RG-8X coax precisely — this length sets the resonant frequency of the driven element
- Short both ends (braid to center) using short solder bridges — keep leads under 5 mm
- At the center, carefully separate and prepare the feedpoint terminals — 20 mm of stripped center conductor and a clean braid pigtail, both accessible for connection to the feedpoint connector
- Form the coax into a straight line (it can be curved slightly but should be as straight as possible) and mount it in place of element 2 on the boom, centered at the 375 mm position
Mount All Elements and Install Feedpoint Assembly
Mount all six elements to the boom in order — reflector first, then driven element (folded dipole), then directors 1 through 4. Verify each element is perpendicular to the boom before tightening. Elements that are not perpendicular to the boom produce a skewed radiation pattern.
Install the feedpoint assembly at the driven element center. Mount a small weatherproof project box on the boom adjacent to the driven element center. Inside the box: the feedpoint connector (N-type or BNC), and the ferrite choke (5 turns of feedline coax through a type-43 ferrite toroid). Connect the feedpoint terminals of the folded dipole to the inner connector terminals. Route the feedline coax from the connector box along the boom toward the mast, securing with UV-resistant cable ties.
Initial NanoVNA Sweep at Ground Level
Hold the antenna horizontally at waist height (at least 1 meter above the ground, pointed away from metal structures) and connect the NanoVNA. Sweep 130–160 MHz and look for the SWR minimum:
Mount to Mast and Final Tuning
Mount the antenna on its mast at a height of at least 2 meters (6.5 feet) for final tuning. Connect the NanoVNA at the feedpoint (not at the shack end of the coax — the coax length at VHF shifts the apparent resonance significantly). Sweep 140–150 MHz:
Weatherproof and Verify On-Air Performance
Apply self-amalgamating tape over the feedpoint connector and coax connection. Seal the feedpoint project box with RTV sealant at all cable entry points. Apply a coat of clear lacquer spray to all element surfaces and the boom — this prevents oxidation that gradually degrades VHF performance over months.
Verify on-air performance by orienting the antenna toward a known beacon or repeater and noting the signal strength, then rotating 180° and verifying a significant null. A well-built 6-element 2m Yagi should produce a clear directional pattern that is unmistakable on the S-meter. Also test during a VHF contest or weak-signal net — the Yagi's gain over a vertical or horizontal dipole should be immediately apparent as an improvement in both transmit and receive signal levels compared to an omni antenna.
Weak-Signal VHF Operation
The 2m Yagi excels on the weak-signal portion of the 2m band (144.0–144.4 MHz) where SSB and CW contacts over hundreds of miles are routine during band openings:
- Tropo (tropospheric ducting): under favorable atmospheric conditions, 2m SSB contacts of 500–1500 miles are possible with this antenna. A 6-element Yagi at 30 feet provides enough gain to work most tropo openings with 100W.
- Sporadic-E: summer months bring E-layer ionization that supports 2m contacts at 1000+ miles. The Yagi's directivity helps pick out the wanted signal in the noise.
- Meteor scatter: brief contacts during meteor showers using WSJT digital modes (MSK144). The Yagi's gain is directly useful for these low-signal-level contacts.
- VHF contesting: the ARRL January and June VHF contests, and CQ WW VHF, are the primary operating venues for this antenna. A single 6-element Yagi puts a new operator on a competitive footing for regional contacts.
Satellite Operation
The 2m Yagi is one of two antennas needed for satellite operation on the FM and linear transponder satellites. The other is a 70cm Yagi. Together they enable contacts through the OSCAR and AMSAT constellation of amateur satellites:
- FM satellites: SO-50, AO-91, AO-92 — require a 2m uplink and 70cm downlink (or vice versa). A 6-element 2m Yagi with 5W produces strong signals through these satellites with no pointing accuracy required.
- Linear transponder satellites: AO-7, FO-29 — SSB through the satellite's linear transponder. Requires more precise pointing and attitude tracking as the satellite moves across the sky. A handheld Yagi works well for this — this antenna is small enough to hold and manually track a satellite pass.
- Doppler shift: satellite operation requires tuning for Doppler shift as the satellite moves. Resonating the antenna at 145.5–146.0 MHz ensures the antenna covers the full FM uplink segment even with Doppler correction.
| Symptom | Most likely cause | Diagnosis | Fix |
|---|---|---|---|
| SWR minimum not visible in 130–160 MHz sweep | Folded dipole feedpoint fault — open circuit or short | Disconnect feedline; measure impedance directly at driven element center with NanoVNA | Check folded dipole end shorts and feedpoint split; verify neither element half contacts boom metal |
| SWR minimum at correct frequency but minimum SWR above 2.5:1 | Folded dipole construction error or poor feedpoint connection | Measure driven element total length — should be 975 mm ± 3 mm | Re-solder feedpoint connections; verify folded dipole length; check ferrite choke placement |
| SWR minimum 5+ MHz away from target | Elements wrong length — possibly mixed up during assembly | Measure each element and compare to table — any element more than 3 mm off is wrong | Re-cut incorrect elements; verify all positions from table before reassembly |
| SWR varies when feedline is moved or touched | No ferrite choke — common-mode current on feedline | Touch the feedline coax during transmit — if SWR changes, common-mode current is flowing | Install ferrite choke (5 turns of feedline coax through type-43 toroid) at feedpoint |
| No directional pattern — omnidirectional on 2m | All elements same length (parasitic elements not installed) or elements too long | Measure director lengths — they should be progressively shorter from D1 to D4 | Verify element lengths against table; re-cut any incorrectly sized elements |
| SWR rises significantly after outdoor exposure | Oxidation at element-to-insulator contact points or feedpoint moisture ingress | Clean contacts and re-measure — if SWR improves, corrosion is the cause | Apply clear lacquer to all aluminum surfaces; re-weatherproof feedpoint; check all element clamp connections |
Can I use this Yagi for FM repeater operation as well as weak-signal SSB?
Technically yes, but with trade-offs. FM repeater operation in most areas uses 146–148 MHz — the 6-element Yagi tuned for 144.2 MHz will show SWR of 3–5:1 at 147 MHz. The radio's internal ATU may handle this, but the SWR mismatch reduces efficiency noticeably. For an operator who primarily uses repeaters at 147 MHz and occasionally uses weak-signal SSB at 144.2 MHz, consider building two antennas — this Yagi for weak-signal use and a separate vertical or 2-element beam for the repeater. Alternatively, tune the Yagi to 145.5 MHz as a compromise that keeps SWR below 2:1 from 144.0 to 147.0 MHz — a broader but shallower tuning that serves both applications acceptably.
How do I aim the Yagi during a VHF contest or band opening?
For fixed-station use during contests, mount the Yagi on a mast with a TV antenna rotator (a Yaesu G-250 or similar light rotator handles a 6-element 2m Yagi easily) and use a compass bearing to aim the antenna. Most VHF operators mark the compass headings for major population centers and grid squares on their rotator controller. For portable or SOTA operation, the Yagi is typically hand-held or mounted on a camera tripod with manual azimuth rotation. Pointing accuracy of ±5° is adequate for a 6-element Yagi with a 50° beamwidth — no precise tracker is needed. Listen for the signal peak as you rotate and fix on that bearing.
How many elements should I build for EME (moon bounce) operation?
Earth-Moon-Earth operation on 2m requires significantly more gain than this 6-element Yagi provides. A practical minimum for single-antenna EME using WSJT digital modes is approximately 12–15 elements (18–21 dBd gain). Most EME stations use either a large single Yagi (16+ elements, 24+ dBd), a pair of stacked Yagis (+3 dB over single), or a large array of 4 or more Yagis. The 6-element Yagi in this guide is a starting point — it is the right first antenna for VHF weak-signal, satellite, and meteor scatter operation, and building and operating it will teach you whether EME is the direction you want to pursue with more investment. Many operators progress from this 6-element to a 10–12-element Yagi as a second build when EME interest develops.
Does the Yagi need to be polarized horizontally for weak-signal SSB?
Yes — horizontal polarization is the standard for 2m weak-signal SSB and CW operation. Virtually all weak-signal stations use horizontal polarization, and a vertically polarized antenna pointed at a horizontally polarized station loses approximately 20 dB of signal due to polarization mismatch — making contacts essentially impossible. Mount this Yagi with the elements pointing horizontally (boom is horizontal, elements are horizontal) for weak-signal operation. For FM repeater operation (which uses vertical polarization) the Yagi should be mounted with elements vertical — or better, use a separate vertical antenna for FM operation and keep the Yagi horizontal for weak-signal use.
Can I build a longer version of this Yagi for more gain?
Yes — the DL6WU design used in this guide scales linearly. Additional directors at the front of the boom increase gain by approximately 1 dBd per 2 additional elements (at typical spacings for this design). The element dimensions follow the same DL6WU progression — each additional director is slightly shorter than the previous, at the same spacing ratio. A 10-element version produces approximately 14–15 dBd and is still manageable mechanically at approximately 12 feet of boom length. A 16-element version reaches approximately 18 dBd on a 20-foot boom — approaching the lower limit of EME capability. Each extension requires no changes to the existing elements or feedpoint — simply add directors at the specified spacings and lengths. The DL6WU design extends without modification.
What power level is safe for this Yagi?
The antenna itself handles any legal limit power — the 3/16-inch aluminum elements and folded dipole coax have essentially no power handling limitation at 2m. The practical limits are the feedpoint connector (N-type handles 500W easily; BNC is rated for approximately 100W) and the feedline coax (LMR-400 handles legal limit at 144 MHz without concern). For QRP WSJT-mode satellite and meteor scatter work, 5–25W is the typical power level and the antenna is trivially safe at these levels. For high-power EME operation at legal limit (1500W), upgrade to N-type connectors throughout and verify the feedpoint box can dissipate any reflected power without overheating.