23centimeter

The 23-centimeter band, commonly referred to as the 23 cm band, designates a portion of the microwave radio spectrum around 1.2 to 1.3 GHz, corresponding to roughly a 23-centimeter wavelength. The name follows the traditional convention of naming bands by their approximate wavelength.

In amateur radio, the 23 cm band is typically allocated to about 1,240–1,300 MHz in many countries. Exact allocations and operating rules vary by regulator, with some administrations offering narrower or broader ranges and different licensing requirements. The band is used by hobbyists and researchers for two-way communications and microwave experimentation.

Typical applications include amateur microwave communications, high-speed digital links, and Earth–Moon–Earth (EME) experiments. The higher frequency enables high-gain, narrow-beam antennas such as parabolic dishes and high-gain Yagi arrays, which support focused, short-range to long-range line-of-sight links. Propagation is largely line-of-sight, though occasional tropospheric ducting or sporadic-E conditions can extend reach under favorable circumstances.

Equipment for the 23 cm band often relies on transverters to connect conventional VHF/UHF transceivers to frequencies in the 1.24–1.3 GHz range. System components typically include low-noise amplifiers, mixers, filters, and precise frequency synthesis, paired with careful antenna pointing and feedline management. Due to higher atmospheric attenuation and greater hardware losses at these frequencies, microwave practice emphasizes meticulous design and calibration.

Regulatory status varies by country and region; licensing is commonly required, and limits on power, emission types, and band edges differ between jurisdictions. Prospective operators should consult their national communications authority to determine exact allocations and permissible uses for the 23-centimeter band.