Ka band

The K_a band ("kay-ay band") covers the radio frequencies of 26.5–40 GHz, i.e. wavelengths from slightly over one centimeter down to 7.5 millimeters. The K_a band is part of the K band of the microwave band of the electromagnetic spectrum. This symbol refers to "K-above": in other words, the band directly above the K-band. The 30/20 GHz band is used in communications satellites, uplink in either the 27.5 GHz and 31 GHz bands, and high-resolution, close-range targeting radars aboard military airplanes. Some frequencies in this radio band are used for vehicle speed detection by law enforcement. The Kepler Mission uses this frequency range to downlink the scientific data collected by the space telescope.

The designation "K_a-band" is from Kurz-above, which stems from the German word "kurz" meaning short.

In satellite communications, the K_a band allows higher bandwidth communication. It is used in the Inmarsat I-5 system and will be used in the Iridium Next satellite series, as well as the James Webb Space Telescope. The K_a band is more susceptible to rain attenuation than is the K_u band, which in turn is more susceptible than the C band.

This technical document from SpaceX proposes a system of 4,000 satellites using the K_a and K_u band frequencies as a backbone for a global broadband service.