k-Band
Understanding K-Band
K-band is the middle segment of the broader K-range of microwave frequencies. Its defining feature is the 22.2 GHz water vapor absorption line, which as little as a few dB/km of additional attenuation. This limits long-range applications but is useful for radio astronomy observations of water vapor in the universe.
| Characteristic | 24 GHz | 77 GHz | 79 GHz |
|---|---|---|---|
| Bandwidth | 250 MHz | 1 GHz | 4 GHz |
| Range Resolution | 60 cm | 15 cm | 3.75 cm |
| Antenna Size | Moderate | Small | Small |
| Regulation | ISM (global) | Licensed | Licensed (UWB) |
K-Band Applications
- Police radar: 24.05-24.25 GHz (K-band in US) for speed enforcement.
- Automotive: 24 GHz short-range radar for parking assist and blind-spot detection (being replaced by 77 GHz).
- Radio astronomy: Water vapor line at 22.235 GHz used for atmospheric and interstellar observations.
- Satellite communications: Some crosslinks and inter-orbit links.
K vs Ku vs Ka
- Ku-band: 12-18 GHz. Satellite TV, maritime VSAT.
- K-band: 18-26.5 GHz. Water vapor absorption. Limited use.
- Ka-band: 26.5-40 GHz. High-capacity satellite, 5G, radar.
Frequently Asked Questions
What is K-band?
K-band covers 18-26.5 GHz. It contains the 22.2 GHz water vapor absorption line, which limits long-range use. Applications include police radar (24 GHz), automotive sensors, and radio astronomy.
Why is K-band less popular than Ku or Ka?
The water vapor absorption at 22.2 GHz creates additional atmospheric loss (several dB/km), making K-band unsuitable for long-range satellite and terrestrial links. Ku-band (below) and Ka-band (above) avoid this absorption and offer more usable spectrum.
What is the origin of the K-band name?
K stands for 'kurz' (German for 'short'), as it was originally named during WWII radar development. Ku = K-under (below K), Ka = K-above (above K). The three K bands span 12-40 GHz.