End-Fed Half-Wave (EFHW)

Wire Antennas

A half-wave wire fed at its high-impedance end through a transformer.

Band: HF (multiband on harmonics)
Gain: ~2 dBi
Polarization: Linear (depends on deployment)

Radiation / wave patterns

Idealized radiation pattern of the End-Fed Half-Wave (EFHW) — Idealized azimuth radiation pattern (illustrative, generated). Radial scale in dB.

How & why it works

Instead of feeding a half-wave wire at its low-impedance center, the EFHW feeds it at the end, where the impedance is very high (a few thousand ohms). A 49:1 (or 64:1) auto-transformer steps that down to about 50 ohms so coax can be used. Because a half-wave on the lowest band is also resonant on its harmonics, a single wire often works several bands, and end feeding makes it easy to deploy as a sloper or along a fence without a center support.

Real-world uses

Portable and POTA/SOTA operation, stealth home installations, and quick field setups.