The half-wave dipole is the reference antenna in ham radio: a straight wire cut to a half wavelength and fed in the centre. It's efficient, cheap and predictable, which is why almost every other antenna's gain is quoted against it (0 dBd).
A dipole's total length follows the classic 468 / f(MHz) feet rule (about 143 / f(MHz) metres, with a 0.95 velocity factor). Feed the centre with 50-ohm coax through a 1:1 current balun, and hang it as high and level as you can — around half a wavelength up gives the best low-angle performance for DX.
| Band | Total tip-to-tip length | Each leg from the center |
|---|---|---|
| 160m | 74.95 m / 245.9 ft | 37.47 m / 122.9 ft |
| 80m | 37.97 m / 124.6 ft | 18.99 m / 62.3 ft |
| 60m | 26.58 m / 87.2 ft | 13.29 m / 43.6 ft |
| 40m | 20.06 m / 65.8 ft | 10.03 m / 32.9 ft |
| 30m | 14.06 m / 46.1 ft | 7.03 m / 23.1 ft |
| 20m | 10.05 m / 33.0 ft | 5.02 m / 16.5 ft |
| 17m | 7.86 m / 25.8 ft | 3.93 m / 12.9 ft |
| 15m | 6.71 m / 22.0 ft | 3.35 m / 11.0 ft |
| 12m | 5.71 m / 18.7 ft | 2.85 m / 9.4 ft |
| 10m | 5.00 m / 16.4 ft | 2.50 m / 8.2 ft |
| 6m | 2.82 m / 9.3 ft | 1.41 m / 4.6 ft |
Model this antenna interactively → for gain, takeoff angle and azimuth/elevation patterns.
About 10.05 m (33 ft) tip to tip, so 5.02 m (16.5 ft) per leg, cut for 14.175 MHz.
Total length in feet is roughly 468 divided by the frequency in MHz; in metres it's about 143 divided by the frequency in MHz. Trim for lowest SWR.
Aim for about half a wavelength above ground for good DX takeoff angles. A quarter wavelength still works well for shorter regional contacts.
A 1:1 current balun (choke) at the feedpoint is recommended. It keeps RF off the coax shield so the pattern stays clean; no impedance transformer is needed.