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Full-Wave Loop

Loop Antennas HF Receive 🔧 Buildable at home

A loop one wavelength in circumference with gain and low noise.

Band
HF
Gain
~3-4 dBi
Polarization
Horizontal or vertical (feed dependent)

Photos

Real-world photo of a Full-Wave Loop in use
Real-world example. Source: Wikimedia Commons (CC0; uhoh).

Radiation / wave patterns

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

Radiation pattern of the Full-Wave Loop
Bidirectional broadside to the loop; orientation (vertical vs horizontal mounting) sets the polarization and which way the lobes point.

How & why it works

A full-wave loop—square, triangular (delta), or round—has a circumference of about one wavelength, so a full standing wave fits around it. This makes it a resonant, relatively low-impedance antenna (around 100-130 ohms) with a couple of dB more gain than a dipole and a slightly higher radiation angle that favours nearer contacts. Being a closed loop, it tends to pick up less local electrical noise, which receivers appreciate on the low bands.

Real-world uses

Low-noise HF receiving and transmitting, NVIS regional work, and quiet home stations.

Make one at home

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

See the finished antenna pictured above ↑.

A full-wave (delta) loop is a quiet, slightly-higher-gain alternative to a dipole — a triangle of wire fed at a corner.

You’ll need

  • Wire ≈ 306 ÷ f(MHz) metres (one wavelength) for the loop
  • Three supports (or one apex support for a delta), insulators
  • 50-ohm coax + 1:1 choke (feed impedance is ~100–120 Ω; a 1:1 is a usable compromise, or use a 2:1/4:1 for a better match)

Build

  1. Form the wire into a triangle (delta) with the apex up.
  2. Feed at a bottom corner for horizontal polarization (or a side corner for vertical).
  3. Support the corners with rope and insulators.

Tune

Trim the loop length for lowest SWR. Loops are quiet on receive — good for the low bands.

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.