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Half-Wave Dipole

Wire Antennas

The simplest resonant antenna: two straight conductors fed at the center.

Band: HF to UHF (scaled to band)
Gain: ~2.15 dBi
Polarization: Linear (orientation of the elements)

Photos

Real-world photo of a Half-Wave Dipole in use — Real-world example. Source: Wikimedia Commons (CC BY-SA 4.0; 4shadoww).

Radiation / wave patterns

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

How & why it works

A half-wave dipole is a conductor cut to roughly half the wavelength of the signal, split in the middle where the feedline connects. At resonance the standing-wave current is maximum at the center and the voltage is maximum at the ends, giving a feedpoint impedance near 73 ohms that matches common coax reasonably well. It is the reference against which other antennas' gain is often measured (dBd).

Real-world uses

Amateur radio HF/VHF, FM broadcast receive, and as a building block for more complex arrays such as the Yagi-Uda.