What frequency bands does the radar work in and what are the advantages of working in different frequency bands?

The earliest electromagnetic wave wavelength used for searching radar was 23cm, which was defined as L-band (prefix of English Long), and later the center wavelength of this band became 22cm. When an electromagnetic wave with a wavelength of 10cm is used, its band is defined as S-band (English short prefix, meaning electromagnetic wave shorter than the original wave). After the appearance of fire control radar, which mainly uses 3cm electromagnetic wave, the electromagnetic wave with 3cm wavelength is called X-band, because X represents a certain point on the coordinate. In order to combine the advantages of X-band and S-band, a radar with a center wavelength of 5cm gradually appeared, which is called C-band (C is the prefix of "combination" in English). Following the British, the Germans began to independently develop their own radar, and they chose 1.5cm as the central wavelength of their radar. The electromagnetic wave of this wavelength is called K-band (K = Kurtz, the prefix of "short" in German). Unfortunately, the wavelength chosen by the Germans with its unique "accuracy" can be strongly absorbed by water vapor. Therefore, the radar in this band cannot be used in rainy and foggy weather. In order to avoid this absorption peak, the radar designed after the war usually adopts Ka-band (Ka, abbreviation of K-above, meaning above K-band) and slightly lower (Ku, abbreviation of K-under, meaning below K-band). Finally, because the earliest radar used meter wave, this band is called P band (P is the abbreviation of Previous, which is the prefix of "past" in English). The system is very complicated and inconvenient to use. Finally, it was replaced by a wavelength division system based on actual wavelength. The conversion of these two systems is as follows. Original P-band = current A/B band, original L-band = current C/D band, original S-band = current E/F band, original X-band = current I/J band, original K-band = current China microwave sub-band code (from microwave technology foundation, Xidian and Liao Chengen) band code nominal wavelength (cm) frequency wavelength (cm) wavelength range (cm). kloc-0/02-46025438+0.25 18-27 1.67- 1. 1 1ka 0.827-40 1. 1 1-0.75 u 0.640-600。 The wavelength propagation characteristics of the symbol frequency band of China's frequency division method are mainly used for very low frequency VLF3-30KHz ultra-long wave 1km- 100km coastal submarine communication based on space wave; Long-distance communication; Ultra-long-distance navigation low-frequency LF30-300KHz long wave 10Km- 1Km ground wave-based transoceanic communication; Medium-distance communication; Underground stratum communication; Long-range navigation medium frequency MF0.3-3MHz medium wave 1Km- 100m ground wave and sky wave ocean communication; Amateur radio communication; Mobile communication; Medium-range navigation HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF. HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF HF H F HF HF HF international fixed-point communication VHF30-300MHz meter wave 10m- 1m space wave ionospheric scattering (30-60mhz); Meteor trail communication; Artificial ionospheric communication (30-144 MHz); Communication with space flight bodies; Mobile communication UHF0.3-3GHz decimeter wave 1m-0. 1m space wave small-capacity microwave relay communication; (352-420 MHz)； Troposcatter communication (700- 10000 MHz); Medium-capacity microwave communication (1700-2400 MHz) UHF SHF3-30 GHz centimeter wave 10cm- 1cm space wave high-capacity microwave relay communication (3600-4200 MHz); High-capacity microwave relay communication (5850-8500mhz); Digital communication; Satellite communication; When the international maritime satellite communication (1500-1600 MHz) VHF 30-300 GHz millimeter wave 10 mm space wave communication enters the atmosphere; Waveguide communication name symbol frequency band wavelength propagation characteristics are mainly used for editing. The advantage of applying radar in this section is that it can detect long-distance targets day and night, without being blocked by fog, clouds and rain. It has the characteristics of all-weather and all-weather, and has certain penetration ability. Therefore, it is not only an indispensable military electronic equipment, but also widely used in social and economic development (such as weather forecast, resource exploration, environmental monitoring, etc.). ) and scientific research (celestial research, atmospheric physics, ionospheric structure research, etc. Spaceborne and airborne synthetic aperture radars have become very important sensors in remote sensing. A radar targeting the ground can detect the precise shape of the ground. Its spatial resolution can reach several meters to tens of meters, regardless of distance. Radar shows good application potential in flood monitoring, sea ice monitoring, soil moisture survey, forest resources survey and geological survey. [ 1]