Modern war is swift and fleeting. Often the winner in a battle is the one who is the first to be able to detect a potential threat and react adequately to it. For more than seventy years, a radar method based on the emission of radio waves and the registration of their reflections from various objects has been used to search for an enemy on land, sea and air. Devices that send and receive such signals are called radar stations (radars) or radars.
The term "radar" is an English abbreviation (radio detection and ranging), which was launched in 1941, but has long become an independent word and entered into most languages of the world.
The invention of the radar is certainly a landmark event. The modern world is hard to imagine without radar stations. They are used in aviation, in sea transportation, with the help of radar weather is predicted, violators of traffic rules are detected, the earth's surface is scanned. Radar systems (RLK) have found their application in the space industry and navigation systems.
However, the most widely used radar found in military affairs. It should be said that this technology was originally created for military needs and reached the stage of practical implementation just before the beginning of the Second World War. All the largest countries participating in this conflict actively (and not without result) used radars for reconnaissance and detection of enemy ships and aircraft. It is safe to say that the use of radar decided the outcome of several iconic battles both in Europe and in the Pacific theater of hostilities.
Today, radars are used to solve an extremely wide range of military tasks, from tracking the launch of intercontinental ballistic missiles to artillery reconnaissance. Each aircraft, helicopter, warship has its own radar complex. Radars are the basis of the air defense system. The newest radar complex with a phased antenna array will be installed on the promising Russian tank "Armata". In general, the diversity of modern radar is amazing. These are completely different devices, which differ in size, characteristics and purpose.
It is safe to say that today Russia is one of the recognized world leaders in the development and production of radar stations. However, before we talk about trends in the development of radar systems, a few words should be said about the principles of radar operation, as well as about the history of radar systems.
How does radar work
A location is a method (or process) of determining the location of something. Accordingly, radiolocation is a method of detecting an object or object in space using radio waves, which are emitted and received by a device called a radar or radar.
The physical principle of operation of the primary or passive radar is quite simple: it transmits radio waves into space, which are reflected from surrounding objects and return to it in the form of reflected signals. Analyzing them, the radar is able to detect an object at a certain point in space, and also to show its main characteristics: speed, altitude, size. Any radar is a complex radio engineering device consisting of many components.
The composition of any radar includes three main elements: the signal transmitter, antenna and receiver. All radar stations can be divided into two large groups:
- impulse;
- continuous action.
A pulse radar transmitter emits electromagnetic waves for a short period of time (a fraction of a second), the next signal is sent only after the first pulse returns and enters the receiver. Pulse repetition frequency - one of the most important characteristics of the radar. Low frequency radars send several hundred pulses per minute.
The antenna of a pulse radar works both on reception, and on transfer. After the signal is emitted, the transmitter is turned off for a while and the receiver is turned on. After his reception is the reverse process.
Pulse radar has both disadvantages and advantages. They can determine the range of several targets at once, such a radar can easily do with one antenna, the indicators of such devices are simple. However, the signal emitted by such a radar should have a rather large power. You can also add that all modern tracking radar performed by the pulse pattern.
In pulsed radar stations, magnetrons, or traveling-wave lamps, are usually used as a signal source.
The radar antenna focuses the electromagnetic signal and sends it, picks up the reflected pulse and transmits it to the receiver. There are radars in which the reception and transmission of a signal are made by different antennas, and they can be located at a considerable distance from each other. Radar antenna can emit electromagnetic waves in a circle or work in a particular sector. The radar beam can be spirally or cone-shaped. If necessary, the radar can monitor the moving target, constantly pointing at it with the help of special systems.
The function of the receiver is to process the received information and transfer it to the screen from which it is read by the operator.
In addition to pulsed radar, there are continuous radars that constantly emit electromagnetic waves. Such radar stations in their work use the Doppler effect. It lies in the fact that the frequency of an electromagnetic wave reflected from an object that approaches the signal source will be higher than from a moving away object. The frequency of the emitted pulse remains unchanged. Radars of this type do not fix fixed objects, their receiver picks up only waves with a frequency higher or lower than emitted.
A typical Doppler radar is a radar, which is used by traffic police to determine the speed of vehicles.
The main problem of continuous-action radars is the impossibility of using them to determine the distance to the object, but during their operation there is no interference from fixed objects between the radar and the target or behind it. In addition, Doppler radar is a fairly simple device, which is enough to operate signals of low power. It should also be noted that modern radar stations with continuous radiation have the ability to determine the distance to the object. This is done by changing the frequency of the radar during operation.
One of the main problems in the operation of pulsed radar are interferences that come from fixed objects - as a rule, this is the earth's surface, mountains, hills. When airborne pulse radars of airplanes are operating, all objects below are “obscured” by a signal reflected from the earth's surface. If we talk about ground or shipborne radar complexes, then for them this problem is manifested in the detection of targets flying at low altitudes. To eliminate such interference, the same Doppler effect is used.
In addition to the primary radar, there are also so-called secondary radars, which are used in aircraft to identify aircraft. The composition of such radar systems, in addition to the transmitter, antenna and receiving device, also includes an aircraft transponder. When irradiated with an electromagnetic signal, the respondent issues additional information about the height, route, board number, and its nationality.
Also, radar stations can be divided by the length and frequency of the wave at which they operate. For example, to study the surface of the Earth, as well as to work at significant distances, waves of 0.9-6 m (frequency 50-330 MHz) and 0.3-1 m (frequency 300-1000 MHz) are used. Radar with a wavelength of 7.5-15 cm is used for air traffic control, and over-the-horizon radar of missile launch detection stations operate on waves with a length from 10 to 100 meters.
History of radar
The idea of radar appeared almost immediately after the discovery of radio waves. In 1905, Christian Hülsmeier of Siemens, a German company, created a device that could detect large metal objects using radio waves. The inventor proposed to install it on ships so that they could avoid collisions in conditions of poor visibility. However, shipping companies are not interested in the new device.
Experiments were conducted with radar in Russia. At the end of the 19th century, Russian scientist Popov discovered that metal objects prevent the propagation of radio waves.
In the early 20s, American engineers Albert Taylor and Leo Yang managed to detect a passing ship using radio waves. However, the state of the radio industry at that time was such that it was difficult to create industrial designs of radar stations.
The first radar stations that could be used to solve practical problems appeared in England around the mid-thirties. These devices were very large, they could only be installed on land or on the deck of large ships. Only in 1937, a prototype of a miniature radar was created, which could be installed on an aircraft. By the beginning of World War II, the British had a developed chain of radar stations called Chain Home.
Engaged in a promising new direction in Germany. Moreover, it must be said, unsuccessfully. As early as 1935, the Commander-in-Chief of the German fleet, Reder, was shown a functioning radar with an electron-beam display. Later, on the basis of it were created serial samples of the radar: Seetakt for the naval forces and Freya for air defense. In 1940, the Würzburg radar fire control system began to flow into the German army.
However, despite the obvious achievements of German scientists and engineers in the field of radiolocation, the German army began to use radars later the British. Hitler and the top of the Reich considered radars to be exclusively defensive weapons, which the victorious German army didn’t really need. It is for this reason that the Germans had only eight Freya radars deployed by the beginning of the battle for Britain, although in terms of their characteristics they were at least as good as their British counterparts. In general, we can say that it was precisely the successful use of radar that largely determined the outcome of the battle for Britain and the subsequent confrontation between the Luftwaffe and the Allied Air Force in the skies of Europe.
Later, the Germans on the basis of the Würzburg system created an air defense line, which was called the "Kammuber line". Using special forces, the Allies were able to unravel the secrets of the work of the German radar, which made it possible to effectively jam them.
Despite the fact that the British entered the "radar" race later on by the Americans and Germans, they were able to overtake them at the finish line and approach the beginning of World War II with the most advanced aircraft radar detection system.
Already in September 1935, the British began to build a network of radar stations, which included twenty radars before the war. It completely blocked the approach to the British Isles from the European coast. In the summer of 1940, a resonant magnetron was created by British engineers, which later became the basis of airborne radar stations installed on American and British aircraft.
Work in the field of military radar were conducted in the Soviet Union. The first successful experiments on the detection of aircraft using radar in the USSR were conducted in the mid 30s. In 1939, the first radar RUS-1 was adopted by the Red Army, and in 1940 - the RUS-2. Both of these stations were put into mass production.
The Second World War clearly showed the high efficiency of the use of radar stations. Therefore, after its completion, the development of new radars has become one of the priorities for the development of military equipment. In time, airborne radars received without exception all military aircraft and ships, and the radar became the basis for air defense systems.
During the Cold War, the United States and the USSR had a new destructive weapon - intercontinental ballistic missiles. Detecting the launch of these rockets has become a matter of life and death. Soviet scientist Nikolai Kabanov proposed the idea of using short radio waves to detect enemy aircraft at long distances (up to 3 thousand km). It was quite simple: Kabanov found out that radio waves with a length of 10-100 meters are able to bounce off the ionosphere, and irradiating targets on the surface of the earth, returning the same way to the radar.
Later, on the basis of this idea, over-the-horizon radar detection of the launch of ballistic missiles was developed. An example of such a radar can serve as "Daryal" - a radar station that for several decades was the basis of the Soviet missile launch warning system.
Currently, one of the most promising areas for the development of radar technology is the creation of a phased-array radar (PAR). Such radars have not one, but hundreds of emitters of radio waves, which are operated by a powerful computer. Radio waves emitted by different sources in the HEADLIGHTS can amplify each other if they coincide in phase, or, conversely, weaken.
The phased-array radar signal can be given any desired shape, it can be moved in space without changing the position of the antenna itself, working with different radiation frequencies. Phased-array radar is much more reliable and sensitive than a radar with a conventional antenna. However, these radars have drawbacks: a big problem is the cooling of the radar with the HEADLIGHT, in addition, they are difficult to manufacture and are expensive.
New radar stations with phased array are installed on fifth-generation fighter jets. This technology is used in the American missile early warning system. Radar complex with phased arrays will be installed on the newest Russian tank "Armata". It should be noted that Russia is one of the world leaders in the development of radar with PAR.
