What Are the Different Uses of Radar?

Military radar is military electronic equipment that uses electromagnetic waves to detect targets. The electromagnetic wave emitted by the radar illuminates the target and receives its echo, thereby finding the target and determining the position, movement direction, speed and other characteristics.

Radar is the English sound of Radar, which means "Radio Detectiori and Ranging". It is an electronic device that uses the reflection of electromagnetic waves on obstacles (targets) to find targets. It usually consists of a transmitting and receiving antenna, a transmitter, a receiver, and a display. Its working principle is: first, a series of short-pulse electromagnetic waves (known as human radio waves) emitted by a radar transmitter illuminates a target (such as a flying airplane), and uses a radar receiver to receive the electromagnetic waves reflected from the target ( Called an echo). Then, the distance between the radar and the target is calculated based on the time difference between the electromagnetic wave transmitted and received by the radar and the propagation speed of the electromagnetic wave in space, and the direction of the target is measured by the antenna pointing angle of the radar receiving echo. In this way, the spatial position of the target is obtained, so that the distance, angle and speed of the target can be tracked. Therefore, the types of targets that radar can detect are very wide, including aircraft, ships, armored vehicles, missiles, satellites, and buildings, bridges, railways, mountains, and rain clouds. The military radar is a radio detection and positioning device specially designed and manufactured for specific military applications. There are many types of military radars. According to the location of their transmitting and receiving antennas, they can be divided into single-base radar, bi-base radar, and multi-base radar. According to their transmitting waveforms, they are divided into continuous wave radar, frequency-modulated continuous wave radar, and pulse wave radar. Platforms can be divided into ground-based radars, airborne radars, shipborne radars, and spaceborne radars; they can be divided into short-wave radar, meter-wave radar, decimeter-wave radar, microwave radar, and millimeter-wave radar according to the wavelength used; Target types and purposes can be divided into early warning radar, interception radar, tracking radar, guidance radar, hunting radar, imaging radar and terrain avoidance radar, etc .; according to their maximum effective distance, they can be divided into line-of-sight radar and over-the-horizon radar. Military radar is one of the important means to obtain all-weather, all-weather strategic and tactical information of land, sea, air and space battlefields. It is the primary sensor of air defense, air defense, sea and land defense weapon systems and command automation systems. It not only can warn, intercept, track, identify, guide and intercept all kinds of flying targets in the air, sea surface, ground and outer space, but also has the ability to image large-scale fixed targets on the ground relying on air or outer space platforms. Although its resolution and measurement accuracy are currently inferior to those of optical and infrared sensors, the performance of military radars in all-weather, all-weather, and large airspace high data rates cannot be replaced by other sensors. Therefore, military radars are extremely important in the military field. Role, has a wide range of applications. ^[1]

The typical radar is a pulse radar, which is mainly composed of antennas and transceivers.

It mainly includes: the maximum working distance and minimum working distance of the radar,

There are many different classification methods for radar. According to different tasks, it can be divided into:

Radar for alert and guidance

Mainly:

In the late 1920s and early 1930s, many countries launched

The basic functions to be completed by military radar are:

(1) Target detection, to determine whether there are targets of interest in the radar observation airspace;

(2) Target parameter measurement, also known as target parameter estimation, is used to determine target position, motion parameters and extract other target feature parameters;

(3) Target classification and identification, used to determine the type of target, distinguish true and false targets, etc.

In order to achieve these increasing new requirements, various radar new technologies have been greatly developed and gradually applied to various advanced radars. These new technologies are mainly manifested in the following 9 aspects:

(1) Expansion of radar frequency band

At the high end of the frequency, it extends to millimeter wave, infrared, and lidar; at the low end, it extends to VHF, UHF, and HF (short wave) bands.

(2) Radar automatic target recognition (ATa)

According to radar observation data and features extracted from radar echoes, classifying, identifying, and discriminating attributes of targets is an important condition for realizing battlefield management and accurate strikes, and is a major issue for radar development today.

(3) Radar imaging technology

Using a large instantaneous bandwidth signal, a high-resolution one-dimensional image of the target can be obtained, and the difference in Doppler frequency shifts in the echo of different parts of the target can be used to obtain the high resolution of the target in terms of angle. ) And the principle of inverse synthetic aperture radar (ISAR) can obtain a high two-dimensional resolution ability, to achieve the target range and angle two-dimensional imaging, and may obtain the target two-dimensional image in terms of ground height and distance, detect hidden in the forest Targets, even underground targets, have greatly expanded the scope of radar applications.

(4) Ultra-low sidelobe antenna technology

High-gain, ultra-low sidelobe antennas (with a maximum sidelobe below a 40 dB) are key technologies for radar anti-interference, anti-ARM, and anti-clutter.

(5) Ultra-wideband radar technology

Radar whose instantaneous relative bandwidth is greater than 25% is called ultra-wideband radar. UWB radar is used in target recognition, radar imaging,

Disturbance, anti-ARM and other aspects are of great significance.

(6) Phased array antenna technology

In addition to ultra-low sidelobe phased array antennas, the development of active phased array antennas, conformal phased array antennas, and wideband phased array antennas is of great significance. Each antenna unit in the active phased array antenna has a transmitting / receiving component (T / R component), which has high performance, high reliability, low cost T / R components, digital beamforming (DBF), adaptive beam As a result, technologies such as digital generation and digital processing of large-time wideband product signals are rapidly developing, and the large-scale adoption of phased array antennas is an important measure to reduce the cost of advanced radars.

(7) Advanced signal processing and data processing technology

With the rapid development of computer and integrated circuit technology, real-time processing of high-speed and large-capacity parallel processing becomes possible. Using it for phased array antenna can realize adaptive digital beamforming. This combines antenna theory with signal processing, and signal processing antennas with a variety of adaptive capabilities have emerged, providing new potential for improving radar performance.

(8) Radar system modeling and simulation technology

With the rapid development of computer technology and simulation technology, it is possible to reasonably determine various tactical and technical indicators during the design phase of radar development, coordinate the allocation of indicators between subsystems, optimize the radar system design, and shorten the radar design cycle; Simulation technology plays a more important role in system software optimization and system performance evaluation. The use of advanced radar system modeling and simulation technology is a key measure to overcome the long development cycle, high technical risk and high cost of advanced radar.

(9) New radar technology, new structure, new materials

In order to achieve the high maneuverability of the radar, to solve the volume and weight constraints encountered in the installation on some complex platforms, the impact of the harsh physical environment, and the problem of high-power heat dissipation, all rely on new processes, new structures and new materials. . At the same time, these new technologies are also important measures to improve radar performance, shorten radar development cycles, and reduce costs ^[2]

The radar's operating frequency band will continue to expand to both ends of the electromagnetic spectrum; the application of microelectronics and solid-state technology will enable the miniaturization of the radar; the use of computers to manage and control the radar will realize the automation of operation, calibration, performance and fault detection, And develop adaptive anti-jamming technology; in small and medium-sized ground, shipborne, and airborne radar, phased array technology will be widely used to achieve the radar's multi-function; it will improve the target's actual image, size, and attitude. The ability to identify and decoy, enhance the radar's ability to resist nuclear attack and anti-radiation missile destruction; new radar systems such as multi-base radar, passive radar, spread-spectrum radar, and noise radar will be developed.