70centimeter

70centimeter is a radio frequency band in the ultra high frequency (UHF) portion of the spectrum. It corresponds to wavelengths around 70 centimeters and, in practice, to frequencies roughly between 420 and 450 MHz, with exact allocations varying by country and ITU region.

In amateur radio, the 70centimeter band is widely used for line-of-sight communications, including FM voice, SSB, CW, and various data modes such as packet radio and satellite links. The band is also used for repeater networks, which extend coverage over large areas. In addition to amateur allocations, some jurisdictions allocate portions of the band to other services.

Propagation on 70centimeter is primarily limited by the line of sight, but can be extended by repeaters and by atmospheric conditions like tropospheric ducting and weather phenomena. Antenna height, power, and frequency offset influence link reliability. It is more susceptible to rain attenuation than lower VHF bands, but generally supports reliable regional communications with proper equipment.

Typical equipment includes handheld and mobile transceivers, base stations, and a variety of antennas such as Yagi, discone, and vertical designs. Many operations use standard FM voice, while more specialized operations use SSB, CW, or data modes. Legal power limits and band plans vary by country and license class.

Development of the band followed the expansion of UHF allocations in the mid-to-late 20th century, and it has become a staple of amateur radio practice worldwide. Operators must comply with national regulations, including licensing, permissible modes, and power limits.