The K_a band (Pronounced: "Kay-A Band") covers the frequencies of 26.5 40 GHz.^[1] 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,^[2] 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.^[3] 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.^[4]

In satellite communications, the K_a band allows higher bandwidth communication, and is going to be used in the upcoming Iridium Next satellite series, for instance. Unlike the K_u and the C bands, however, it is far more susceptible to signal attenuation under rainy conditions.^[5]

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

References

1. ↑ R. Ludwig, P. Bretchko, RF Circuit Design, Theory and Applications, Prentice Hall NJ, 2000.
2. ↑ http://www.tech-faq.com/ka-band.shtml
3. ↑ http://hypertextbook.com/facts/2000/MaxLipkin.shtml
4. ↑ http://www.itwissen.info/definition/lexikon/K-Band-K-band.html (german)
5. ↑ http://www.tele-satellite.us/TELE-satellite-0709/eng/feature.pdf