How to classify radar?

Radar (radio detection and ranging) refers to radio search and ranging. It is a kind of equipment that uses various radio positioning methods to detect and identify various targets and determine target coordinates and other information. In modern military and production, the role of radar is becoming more and more important, especially in the "British" air battle between the British Air Force and the Nazi German Air Force in World War II, which makes the importance of radar very obvious. Radar consists of antenna system, transmitter, receiver, anti-jamming equipment, display, signal processor and power supply. Among them, antenna is one of the key technologies for radar to achieve large airspace, multi-function and multi-target; Signal processor is the core component of multifunctional radar. There are many kinds of radars, which can be classified in many ways: (1) According to the positioning method, they can be divided into active radar, semi-active radar and passive radar. (2) According to the installation position, it can be divided into: ground radar, ship-borne radar, aerial radar, satellite radar, etc. (3) According to the radiation type, it can be divided into pulse radar and continuous wave radar. (4) According to the work, it can be divided into long wave bands: meter wave radar, decimeter wave radar, centimeter wave radar and other bands. (5) It can be divided into: target detection radar, reconnaissance radar, weapon control radar, flight support radar, weather radar, navigation radar, etc. Phased array radar is a new type of multifunctional radar with active electrical scanning array. It not only has the function of traditional radar, but also has other radio frequency functions. The most important feature of active electrical scanning array is that it can radiate and receive RF energy directly into the air. Compared with the mechanical scanning antenna system, it has many remarkable advantages. For example, phased array omits the whole antenna drive system, and when a single component fails, it still maintains high reliability, with an average time to failure of 65438+ million hours, while the average time to failure of mechanically scanned radar antenna is less than 1000 hours. The following mainly introduces the advanced phased array radar.

Overview of phased array radar

Phased array technology appeared as early as the late 1930s. 1937, the United States first started this research work. But it was not until the mid-1950s that two practical shipborne phased array radars were developed. In 1960s, the United States and the former Soviet Union successively developed and equipped several kinds of phased array radars, which were mostly used in ballistic missile defense systems, such as AN/FPS-46, AN/FPS-85, MAR and MSR in the United States, and "henhouse" and "kennel" in the former Soviet Union. These are fixed large phased array radars, and their similarities are: using fixed planar array antennas, with large size, high radiation power and long range. Among them, the AN/FPS-85 in the United States and the "kennel" in the former Soviet Union are the most typical. In 1970s, phased array radar developed rapidly. In addition to the United States and the Soviet Union, many countries have developed and equipped phased array radars, such as Britain, France, Japan, Italy, Germany and Sweden. The most typical ones are: AN/TPN-25, AN/TPQ-37 and GE-592 in the United States, AR-3D in Britain, AN/TPN-25 in France, NPM-5 10 and J/NPQ-P7 in Japan, and RAT-3/KLOC-0 in Italy and Germany. The phased array radar in this period has the characteristics of high maneuverability, miniaturization of antenna, diversification of antenna scanning system and wide application range. In 1980s, phased array radar was further applied because of its many unique advantages. Multifunctional phased array radar is widely used in the new generation of medium-and long-range air defense missile weapon systems that have been equipped and are being developed, and has become an important symbol of the third generation of medium-and long-range air defense missile weapon systems. Thereby greatly improving the operational performance of the air defense missile weapon system. 2 1 century, with the continuous development of science and technology and the characteristics of modern war weapons, the manufacture and research of phased array radar will bring by going up one flight of stairs.

Phased array principle

Phased array is a directional antenna composed of many radiating elements arranged in an array, and the radiation energy and phase closure between the elements can be controlled. A typical phased array uses a computer-controlled phase shifter to change the phase distribution on the antenna aperture to realize spatial beam scanning, that is, electronic scanning, or electrical scanning for short. Phase control can adopt phase method, real-time method, frequency method and electronic feed switch method. Several radiate elements arrange in one dimension are linear arrays, and several radiating elements arrange in two dimensions are planar arrays. The radiating elements can also be arranged on curves or curved surfaces. This kind of antenna is called * * * array antenna. * * * array antenna can overcome the shortcomings of small scanning angle of linear array and area array, and can realize all-space electrical scanning with one antenna. Common * * * shaped array antennas include circular array, circular array, conical array, cylindrical array, hemispherical array and so on. To sum up, phased array radar is named because its antenna is phased array.

classify

Phased array radar can be roughly divided into two categories, namely fully electronically scanned phased array and limited electronically scanned phased array. All-electric scanning phased array can also be called fixed phased array, that is, both azimuth and elevation are electrically scanned, and the antenna array is fixed. Finite electrical scanning phased array is a hybrid antenna, that is, it combines more than two antenna technologies to achieve the desired effect. Firstly, it combines the phase scanning technology with the reflector antenna technology, which has a small electrical scanning angle and only needs a few radiation units, so it can greatly reduce the equipment cost and complexity.

According to the scanning situation, antenna array can be divided into phase scanning, frequency scanning, phase/phase scanning, phase/frequency scanning, machine/phase scanning, machine/frequency scanning, limited scanning and other systems. Phase scanning series uses phase shifter to change the phase relationship to realize beam scanning. Frequency scanning is to realize beam scanning by changing the working frequency. Phase/phase scanning is to realize beam electrical scanning by using two angular coordinates of phase shifter control plane array. Phase frequency scanning uses a coordinate of the phase shifter to control the array, and uses frequency conversion control to realize beam electrical scanning. Machine/phase scanning uses machine scanning in azimuth and phase scanning in elevation. Machine/frequency scanning adopts azimuth machine scanning and pitch frequency scanning.

Characteristics of phased array radar

Phased array radar has great vitality because it is superior to general mechanical scanning radar. It has the following characteristics:

(1) can deal with multiple targets. Phased array radar can search and track at the same time by using the flexibility and rapidity of electronic scanning and the principle of time division or multi-beam. Cooperating with the computer, it can search, detect and track multiple targets in different directions and heights at the same time, and can guide multiple missiles to attack multiple air targets at the same time. Therefore, it is suitable for the operational environment of multi-target, multi-direction and multi-level air strikes.

(2) Multifunctional and flexible. Phased array radar can form multiple independently controlled beams at the same time, which can be used to perform many functions such as searching, detecting, identifying, tracking, illuminating targets, tracking and guiding missiles. A phased array radar can play the role of several special radars. For example, a multi-functional phased array radar of Patriot can complete the functions equivalent to the nine radars of Eagle and Nike-2, and it is far more than the targets they can deal with at the same time. Therefore, the equipment of weapon system can be greatly reduced, thus improving the maneuverability of the system.

(3) Short reaction time and high data rate. Phased array radar does not need antenna driving system, and its beam pointing is flexible, which can realize fast scanning without inertia, thus shortening the time required for target signal detection, recording and information transmission, and having high data rate. Phased array antenna usually adopts digital working mode, which combines radar and digital computer, which can greatly improve the degree of automation, simplify radar operation, shorten the preparation time of target search, tracking and launch control, and facilitate the rapid and accurate implementation of acquisition procedures and data processing. Therefore, the tracking ability of high-speed maneuvering targets in the air can be improved.

(4) Strong anti-interference ability. Phased array radar can synthesize high power by using multiple radiating elements distributed on the antenna aperture, and can reasonably manage energy and control the main lobe gain, and can distribute different transmitting energy in different directions according to needs, which is easy to realize adaptive sidelobe suppression and adaptive anti-interference to help find targets (such as stealth aircraft) far away from targets and small radar reflection surface, and can also improve the ability of anti-radiation missiles.

(5) High reliability. Phased array radar has many array groups, which are used in parallel. Even if a few components fail, they can still work normally, and the possibility of sudden and comprehensive failure is the least. In addition, with the development of solid-state devices, there are more and more solid-state devices of grid array radar, and even all-solid-state children's array radar has been produced, such as the United States. The average time between failures of Patriot radar antenna is as high as 150000 hours. Even if 10% unit is damaged, it will not affect the normal work of the radar.

Of course, phased array radar is not perfect, but also has its shortcomings. The main reason is expensive. The cost of a typical phased array radar is several times higher than that of a general radar. In addition, phased array radar can be said to be powerless to attack short-range ballistic missiles, which is also the reason why the United States and Taiwan Province Province are worried that the mainland will deploy Dongfeng missiles along the coast of Fujian. 199 1 During the Gulf War, when Iraq attacked Israel with Scud missiles, its Patriot missiles could not be effectively attacked at all.