RADIOLOCATION

ABSTRACT

Everyone had already heard the word "radar" in the fifties, but it was pronounced quietly, and everyone thought that the person who uttered this word was involved in some scientific secrets or military. At first, there was massive interest in it, publications in newspapers, films about radar, but after a while, as always happens, mass interest in radar disappeared.

Keywords: radar; radiolocation.

What is radar (hereinafter radar)?

Radar is a field of science and technology that combines methods and means of detecting, measuring coordinates, as well as determining the properties and characteristics of various objects based on the use of radio waves.

With an active response — the object assumes the presence of a responder (radio transmitter), which emits radio waves in response to the received signal. The active response is used to identify objects, as well as to obtain additional information from them (for example, the amount of fuel, the type of object, and much more).

With a passive response, the request signal is reflected from the object and is perceived at the receiving point as a response.

The principle of operation:

Radar is based on the following physical phenomena:

Radio waves are scattered on objects encountered on the path of their propagation: objects with other electrical properties other than those of the propagation medium. In this case, the reflected wave, as well as the actual radiation of the target, allows you to detect the target.

The frequency of the received signal receives an additional shift relative to the frequency of the emitted vibrations when the receiving and radiation points are moved, which makes it possible to measure the speed of movement of the target relative to the radar.

Radar station.

A radar station (radar) or radar is a system for detecting air, sea and land objects, as well as for determining their range. Basically, a method based on the emission of radio waves and the registration of their reflections from objects is used.

The principle of operation of the radar.

The action system is as follows: a large antenna rotates 360 degrees and sends radio waves, between which the angle is 1 degree, and the range of these waves is 100 km, thereby cutting off a square of 2x2 kilometers; the antenna sends and receives 360x90 such waves, since the circumference is 360 and the vertical is 90. If the desired object is located in the cut-off square, then its speed and approximate location are calculated at a certain time and a ray is sent there, which is much thinner than the previous one and serves to capture the target, while the previous one serves to detect the target [1, с. 27].

Primary Radar device.

The structure of the Primary radar is based on: a receiver (a device for receiving electromagnetic waves, followed by converting the information contained in them to a form in which it could be used.), an antenna (a device for emitting and receiving radio waves), a transmitter (a technical device for transmitting signals in the electromagnetic wave section using radio waves).

1. The transmitting device is a source of a high-power electromagnetic signal. Depending on the design, the transmitter operates either in pulse mode, forming repetitive short powerful electromagnetic pulses, or emits a continuous electromagnetic signal.

2. The antenna focuses the receiver signal and generates a diagram, as well as receiving the signal reflected from the target and transmitting this signal to the receiver. Depending on the implementation, the reception of the reflected signal can be carried out either by the same antenna or another one, which can sometimes be located at a considerable distance from the transmitting device.

3. The receiving device performs amplification and processing of the received signal. In the simplest case, the resulting signal is fed to a screen that shows an image synchronized with the movement of the antenna [2, с. 48].

Secondary Radar device.

The principle of operation of the secondary radar is somewhat different from the principle of Primary radar. The Secondary Radar device is based on components: a transmitter, an antenna, a receiver, a signal processor (a specialized microprocessor designed for digital signal processing in real time), an indicator and an aircraft responder with an antenna (an on-board transceiver of aircraft designed to automatically issue information parcels based on a radar request signal.).

The transmitter. It is used to emit request pulses into the antenna at a frequency of 1030 MHz.

The antenna. It is used to emit and receive a reflected signal. The secondary radar is characterized by the fact that the antenna emits at a frequency of 1030 MHz, and receives at a frequency of 1090 MHz.

The receiver. It is used to receive pulses at a frequency of 1090 MHz

The signal processor. It is used for processing received signals

The indicator. It is used to indicate the processed information

An airplane responder with an antenna. It is used to transmit a pulsed radio signal containing additional information back to the radar when receiving a request radio signal [2, с. 57].

The use of radar.

Military use.

One of the first important applications of radar was search and long-range detection for military purposes. Let's turn to history: before the Second World War, Great Britain built a not very perfect, but quite effective network of long-range radar stations to protect against sudden air raids from the English Channel. Nowadays, more advanced radar networks protect Russia and North America from a sudden attack by aircraft or missiles. Ships and aircraft are also equipped with radars. Thus, it became possible to direct fighters at enemy bombers from ground-based tracking radars or from shipboard interception radars; it is also possible to use airborne aircraft radars to detect, track and destroy enemy equipment. Airborne radars are important for searching over land or sea, and to assist in navigation or blind bombing.

Non-military applications.

Ocean-going vessels use radar systems for navigation. On commercial trawlers, the radar is used to detect shoals of fish.

On airplanes, radars are used to solve a number of tasks, including determining flight altitude relative to the ground. At airports, one radar is used for air traffic control, and the other – the approach control radar – helps pilots land the aircraft in poor visibility conditions.

STEALTH technology and its connection with radar.

STEALTH technology to reduce visibility. The surface of the aircraft is assembled from several thousand flat triangles of a special wave-repellent material, therefore:

One of the possible hypotheses why STEALTH is not noticeable to radar is that it reflects waves in such a way that the reflected signal does not return to the enemy's radar station, but somewhere else.

Conclusion.

Radar technology has allowed us to look into a wonderful world for us. There is a place for complex and deep theory, unique experiments, amazing technical solutions and applied applications.

References:

1. Козлов, А. И. Радиолокация. Физические основы и проблемы / А. И. Козлов. – М.: Наука, 2010. – С. 25–35.
2. Физика : учебник для вузов / под ред. Г. Я. Мякишева, Б. Б. Буховцева. – 4-е изд., перераб. и доп. – М. : Просвещение, 2008. – С. 45–85.