Wavelength explorer

Radio wavelength shrinks as frequency rises, and antennas shrink with it. Drag through the amateur bands to see how big a half-wave dipole is and who may transmit there.

Frequency 14.200 MHz

Wavelength: 21.1 m
Half-wave dipole: 10 m (33 ft)
Band: 20 m
Who may transmit here: Amateur Extra

The wave above is drawn at the same scale as the dipole and the person.

How it works

Wavelength in meters is 299.79 divided by frequency in MHz, which the exams round to 300 / f.
The dipole length uses the 468 / f feet rule, which already allows for end effect.
Privileges come from the band chart, which summarizes 47 CFR Part 97.

Learn more: Radio waves and the spectrum

Sources: CODATA value: speed of light in vacuum (NIST); Single Band Dipoles (ARRL); 47 CFR 97.301, Authorized frequency bands (eCFR)

Practice the exam questions: T3 Radio Wave Propagation (Technician), T9 Antennas and Feed Lines (Technician)