TheIEEE K-band is a portion of theradio spectrum in themicrowave range of frequencies from 18 to 27gigahertz (GHz). The range of frequencies in the center of the K-band between 18 and 26.5 GHz are absorbed bywater vapor in the atmosphere due to its resonance peak at 22.24 GHz, 1.35 cm (0.53 in). Therefore these frequencies experience high atmosphericattenuation and cannot be used for long-distance applications. For this reason, the original K-band has been split into three bands:Ka-band, K-band, andKu-band as detailed below.

The K stands forKurz, the German word for 'short'.

Because of the water vapor absorption peak in the center of the band,^[1] the IEEE K-band is conventionally divided into three sub-bands:^[2]

• Ku-band (K-under band, 12–18 GHz): mainly used for satellite communications,direct-broadcast satellite television, terrestrial microwave communications, andradar, especially police trafficspeed detectors.
• K-band (18–27 GHz): due to the 22 GHz water vapor absorption line, this band has high atmospheric attenuation and is only useful for short-range applications.
• Ka-band (K-above band, 26.5–40 GHz): mainly used for satellite communications, radar and experimental communications. NASA'sKepler space telescope is the first NASA mission to use Ka-bandNASA Deep Space Network (NASA DSN) communications.^[3]

TheRadio Regulations of theInternational Telecommunication Union (ITU) allowamateur radio andamateur satellite operations in the frequency range 24.000 GHz to 24.250 GHz, which is known as the1.2-centimeter band. It is also referred to as the K-band byAMSAT.

• K band (infrared)
• K band (NATO)
• K band (Radar Codes)

• Microwave bands
• Satellite broadcasting

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