Radar constellation explanation _ radar constellation explanation

Complete collection of radar satellite details

Radar satellite is a general term for earth observation remote sensing satellites carrying synthetic aperture radar (SAR). Although SAR has been carried on some launched satellites so far, such as SEASAT SAR, Almaz SAR, JERS- 1 SAR and ERS- 1/2 SAR, other sensors are carried on the same remote sensing platform with them. Canada's Radar Satellite (Radarsat) was launched in 1995+065438+ 10, which is a radar system for commercial and scientific experiments. Its main detection target is sea ice, and land imaging is also considered, so it can be used in agriculture, geology and other fields.

Chinese name: radar satellite mbth: radar satellite, comparison and development between radar satellite and other spaceborne SAR systems, multi-parameter (multi-band, multi-polarization and multi-angle), interferometric SAR, spotlight SAR, SAR satellite constellation, small satellite formation networking, formation flying satellite constellation, radar satellite. The system has five beam working modes. That is, (1) standard beam mode, the incident angle is 20 ~ 49, the imaging width is 100 km, the distance and azimuth resolution is 25m×28m(2), the incident angle is 20 ~ 40, and the imaging width and spatial resolution are 150km and 28m× respectively. 45km and10m x 10/0m ④ scanning radar beam. This mode has the ability to quickly image the whole world, with a large imaging width (300 km or 500 km), low resolution (50 m x50 m or 100 m x 100 m) and an incident angle of 20 ~ 49. Compared with other spaceborne SAR systems, Radarsat SAR has the following three characteristics: (1) it has imaging capabilities with different radiation widths of 45km, 75km, 100km, 150km, 300km and 500km; (2) 1 1.6MHz respectively. The all-weather, all-weather and penetrating imaging characteristics of synthetic aperture radar show its superiority compared with optical remote sensors. Radar remote sensing data are also widely used in multidisciplinary fields. In 1990s, space-borne radar developed rapidly, especially polarization radar and interferometric radar technology. After the space shuttle imaging radars SIR-A, SIR-B and SIR-C/X-SAR have successfully completed single-band, single-polarization, multi-band and multi-polarization imaging flights, the space shuttle radar topographic mapping (SRTM) flight is being planned in September 1999. Based on RADARSAT- 1, the RADARSAT-2 radar launched by Canada 200 1 will have full polarization measurement capability; ESA will also carry ASAR on the Envisat- 1 satellite launched in June, which has two polarization modes: co-polarization and cross-polarization. LightSAR, which will be launched in 2002, will be an L-band multipole practical imaging radar with interferometric and scanning modes. Japan's ALOS/PALSAR, which is planned to be launched in the same year, is also a multipolar and multimode radar system. China will also launch its own L-band radar satellite in the next few years. It can be seen that international spaceborne radars are developing in a new direction, and they will provide rich data sources for the development of digital earth. The space application of SAR technology makes it one of the most popular reconnaissance instruments at the end of 20th century, and its application and development has just begun. SAR satellite will have a broader development and application prospect in the future. An important trend in the development of multi-parameter (multi-band, multi-polarization and multi-angle) SAR technology is to make full use of the electromagnetic characteristics of ground objects, which are closely related to the frequency, polarization and incident angle of electromagnetic waves. Therefore, more information about ground objects can be obtained by observing ground objects with electromagnetic waves with different frequencies, polarizations and incident angles. Synthetic aperture radar interferometry has become an important field in the development of synthetic aperture radar technology. The problem of extracting three-dimensional information (elevation information or speed information) of ground objects by SAR is solved. Interferometric SAR has the following three forms: (1) single-channel interferometry, in which two antennas are rigidly mounted on a flight platform, and interferometric measurement is completed in one flight, also called spatial baseline method; (2) Dual-channel interference, which belongs to single antenna structure, requires secondary measurement in time sharing, and the secondary flight trajectories are required to be parallel to each other, also known as time baseline mode; (3) Differential interference, that is, single-channel interference with two antennas installed in the orthogonal direction of the flight path, combined with the third measurement, measures the interference of small fluctuations and displacements. There are many imaging systems in spotlight SAR, mainly stripe and spotlight. The antenna beam of strip SAR forms a fixed intersection angle with the flight trajectory, and with the movement of the carrier, a strip-shaped continuous observation area is formed on the ground, which is suitable for large-area observation. However, during the synthetic aperture time of spotlight SAR, its antenna beam is always staring at the irradiation area to realize small area imaging. Spotlight SAR has higher resolution than strip SAR. In addition, the scattering characteristics of most targets will change dramatically with the observation angle. Because spotlight SAR images in a wide range of observation angles, the obtained image information is more abundant than that of strip SAR. Spotlight SAR and ribbon SAR are two systems with complementary advantages. Many application departments of SAR satellite constellation hope that the satellite can shorten the repeated observation period in a specific area and obtain dynamic information with high time resolution. To solve this problem, we can not only increase the coverage density in the middle and low latitudes with small orbital inclination to shorten the repetition period, but also organize international cooperation in satellite observation, such as the joint flight of SIR-C and X-SAR, and organize formation flights of SIR-C/X-SAR and ERS/Envisat or Radarsat in the future. However, only actively developing small satellite constellations for earth observation is the most effective technical difficulty to solve dynamic reconnaissance. It is necessary to ensure the technical performance of reconnaissance, reduce its weight and power consumption, and have enough accuracy in orbit measurement and attitude control to ensure the quality of reconnaissance data. The formation network of small satellites consists of several small satellites with certain flight trajectory shapes, forming a "virtual satellite" in a distributed way. This is the development of small satellites in a faster, more economical and better direction, and it is also another brand-new application field being developed for small satellites at present. The military application of formation flying is one of the earliest areas of concern. On the one hand, satellite formation flight can realize earth observation and obtain ground target information; On the other hand, the cooperation of multiple satellites can achieve more functions, such as stereo imaging, which can provide services for military needs. The virtual large satellite for stereo reconnaissance is composed of multiple micro-satellites, which can replace a single satellite with the same function with lower cost, higher reliability and survivability, and give full play to the characteristics and advantages of micro-satellites. Although the formation flying satellite constellation expands its functions and improves the performance of a single satellite, the dense distribution of satellites in formation flying still has discontinuous coverage; If continuous coverage is to be achieved, formation flying will form a satellite constellation, that is, formation flying satellite constellation. In the traditional satellite constellation, the unit that constitutes the constellation is a single satellite; In the formation flying satellite constellation, the unit that constitutes the constellation is the flying formation. Formation flying can realize stereoscopic imaging function, and the satellite constellation composed of formation flying can realize continuous stereoscopic imaging of a certain area. SAR reconnaissance satellite has the advantages of all-weather, all-weather, unaffected by atmospheric transmission and climate, and strong penetration ability, and has certain penetration ability for some ground objects. These characteristics make it have unique advantages in military applications, and it will surely become a killer weapon in the future battlefield. Therefore, all space countries are planning or developing their own SAR reconnaissance satellites. We have every reason to believe that 2 1 century is a new century for the rapid development of SAR satellites.