← Back to catalog

Yagi-Uda

Directional Antennas HF 🔧 Buildable at home

A directional array of a driven dipole with parasitic reflector and directors.

Band
VHF/UHF (also HF beams)
Gain
~7-15 dBi (depends on element count)
Polarization
Linear (matches the driven element)

Photos

Real-world photo of a Yagi-Uda in use
Real-world example. Source: Wikimedia Commons (CC BY-SA 3.0; Lz1aat).

Radiation / wave patterns

New to these diagrams? How to read a radiation pattern →

Radiation pattern of the Yagi-Uda
Boom aimed horizontally at the target. From above: one strong forward lobe with a small back lobe — point the boom where you want to work.

How & why it works

A Yagi-Uda adds parasitic elements around a driven dipole. A slightly longer reflector behind the driven element and one or more shorter directors in front reshape the radiation pattern by re-radiating the signal with phase shifts that reinforce energy in one direction and cancel it in others. Adding directors narrows the beam and increases forward gain.

Real-world uses

Rooftop TV reception, point-to-point amateur and commercial links, and direction finding.

Make one at home

A practical starting point — always trim and check SWR for your exact frequency.

See the finished antenna pictured above ↑.

A Yagi is a rewarding step up — a driven element plus a reflector and directors on a boom. A 3-element 2 m Yagi is a good first beam.

You’ll need

  • Aluminium tubing/rod for elements; a wooden or non-conductive boom (or insulate metal-boom elements)
  • A driven element with a matching method (gamma match or folded driven element)

Dimensions (3-element, ~146 MHz)

  • Reflector: ~101 cm
  • Driven element: ~96 cm
  • Director: ~92 cm
  • Reflector–driven spacing ~35 cm; driven–director ~35 cm. (Use an online Yagi calculator to refine for your exact frequency and tubing diameter.)

Build & tune

  1. Mount elements on the boom; only the driven element connects to the feed.
  2. Adjust the gamma match (or driven length) for lowest SWR.
  3. Point the director end at the station you want to work.

Safety

  • Keep antennas well clear of power lines — never put one where it could fall onto or contact mains wiring.
  • Don’t transmit while anyone is close to the antenna; mind RF-exposure limits and your local licensing rules.
  • Ground masts and use coax surge protection where appropriate.
  • Cutting/soldering: eye protection and a ventilated space.