The Ka band (Pronounced: "Kay-A Band") covers the frequencies of 26.5 40 GHz. The Ka 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. Kepler Mission uses this frequency range to downlink the scientific data collected by the space telescope.
The designation "Ka-band" is from Kurz-above, which stems from the German word "kurz" meaning short.
In satellite communications, the Ka band allows higher bandwidth communication, and is going to be used in the upcoming Iridium Next satellite series, for instance. Unlike the Ku and the C bands, however, it is far more susceptible to signal attenuation under rainy conditions.
Other Microwave bands
The microwave spectrum is usually defined as electromagnetic energy ranging from approximately 1 GHz to 100 GHz in frequency, but older usage includes lower frequencies. Most common applications are within the 1 to 40 GHz range. Microwave frequency bands, as defined by the Radio Society of Great Britain (RSGB), are shown in the table below:
Footnote: P band is sometimes incorrectly used for Ku Band. "P" for "previous" was a radar band used in the UK ranging from 250 to 500 MHz and now obsolete per IEEE Std 521, see http://www.radioing.com/eengineer/bands.html and http://www.microwaves101.com/encyclopedia/letterbands.cfm. For other definitions see Letter Designations of Microwave Bands
↑ R. Ludwig, P. Bretchko, RF Circuit Design, Theory and Applications, Prentice Hall NJ, 2000.
↑ http://www.itwissen.info/definition/lexikon/K-Band-K-band.html (german)