Microwave is a very high frequency, short wavelength electromagnetic waves. Microwaves are "microscopic" in the sense that their wavelengths are smaller than those of ordinary radio waves. Microwave corresponds to the frequency of about 300MHz ~ 3000GHz, the wavelength range of about 1m ~ 0.1mm. Microwave mainly rely on space wave propagation, in order to increase the communication distance, the antenna is set up higher. In the microwave antenna, the wider application of parabolic antenna, horn parabolic antenna, horn antenna, lens antenna, slot antenna, dielectric antenna, periscope antenna and so on.
Microwave relay communication is the realization of long-distance communication, communication distance is often up to thousands of meters or even tens of thousands of meters or around the Earth's curved surface, due to the influence of the Earth's curved surface and the loss of space transmission, every 50 kilometers or so need to set up relay station will be amplified by the radio wave forwarding and extension. This communication method is also known as microwave relay communication or microwave relay communication.
Radar means radio detection and ranging, i.e., the use of radio methods to discover targets and determine their spatial position. Hence radar is also known as radio location. Radar is an electronic device that uses electromagnetic waves to detect targets. Radar emits electromagnetic waves to the target and receives its echo, thus obtaining information such as the distance from the target to the point where the electromagnetic waves are emitted, the rate of change of the distance (radial velocity), the bearing, the altitude and so on. The advantage of radar is that it can detect long-distance targets during day and night, and it is not blocked by fog, clouds and rain, and it has the characteristics of all-weather, all-day, and it has a certain penetrating ability. Therefore, it has not only become an indispensable electronic equipment for the military, but also widely used in social and economic development (such as meteorological forecasting, resource detection, environmental monitoring, etc.) and scientific research (astrophysical research, atmospheric physics, ionospheric structure research, etc.). Satellite and airborne synthetic aperture radars have become very important sensors in remote sensing today. Radars targeting the ground can detect the precise shape of the ground. Its spatial resolution can be from a few meters to tens of meters and is independent of distance. Radar has also shown good potential for application in flood monitoring, sea ice monitoring, soil moisture survey, forest inventory, geological survey, etc.
Radio astronomy to radio reception technology as a means of observation, the object of observation of all celestial bodies: from the near solar system objects to a variety of objects in the Milky Way galaxy, until the extremely distant beyond the Milky Way target. Radio technology in the radio astronomy band did not really begin to develop until the 1940s. Radio astronomy used a brand new means for astronomy, which had a long history, and opened up new grounds for astronomy. The four major astronomical discoveries of the mid-1960s: quasars, pulsars, interstellar molecules, and microwave background radiation, were all made using radio astronomy. Once upon a time, human beings could only see the optical image of celestial bodies, while radio astronomy shows people another side of celestial bodies - the radio image. Because radio waves can pass through the dust and fog that light waves cannot, radio astronomy observations are able to penetrate into places that were previously invisible by optical means. The vast world of interstellar dust in galactic space was first recognized after the birth of radio astronomy. The cosmic microwave background radiation was an important discovery in radio astronomy, providing strong support for the Big Bang theory. Radio astronomy telescopes are also used to study things much closer to Earth, including solar activity, and the surfaces of the planets in our solar system.
Channel microwave distribution systems are also called broadband wireless technology. The most notable feature is that each downconverter principal vibration point can be different, can be self-selected by the user frequency, that is, multi-point principal vibration, so the downconverter frequency converter signal can be respectively fall in the TV standard channel VHFI, Ⅲ band; additions to the A and B bands; UHF 13 ~ 45CH (band), which is for the user to avoid the local open-circuit wireless TV or CATV occupied channel has great benefits. A variety of service functions can be provided to users, which include point-to-point connection-oriented data services, point-to-multipoint services, and point-to-point connectionless network services. In addition to providing point-to-point and point-to-multipoint data services, MMDS can also support user terminal services, supplementary services, GSM short message services, and a variety of GPRS telecommunication services.