Military Review

Radar on board

Radar on board

Today aviation inconceivable without radar. The airborne radar station (BRLS) is one of the most important elements of the electronic equipment of a modern aircraft. According to experts, in the near future radar systems will remain the main means of detecting, tracking targets and guiding them to a controlled weapons.

We will try to answer the most common questions about the work of the radar on board and tell you how the first radars were created and how promising radar stations can surprise them.

1. When did the first radar on board appear?

The idea of ​​using radar on airplanes came several years after the first ground-based radar appeared. In our country, the ground station Redut became the prototype of the first radar station.

One of the main problems was the placement of the equipment on the plane - a set of the station with power sources and cables weighed about 500 kg. It was unrealistic to install such equipment on a single-seat fighter of that time, so it was decided to station the station in a double Pe-2.

The first domestic airborne radar called the Gneiss-2 was put into service in the 1942 year. Within two years, more than 230 Gneiss-2 stations were released. And in the victorious 1945 year, Phazotron-NIIR, now part of KRET, began serial production of the Gneiss-5s aircraft radar. Target detection range reached 7 km.

Abroad, the first AI Mark I radar - the British - was put into service a little earlier, in 1939. Because of its heavy weight, it was installed on Bristol Beaufighter heavy fighter-interceptors. In 1940, the new model, “AI Mark IV”, entered service. It provided target detection at a distance of up to 5,5 km.

2. What is onboard radar?

Structurally, the radar station consists of several removable units located in the nose of the aircraft: a transmitter, antenna system, receiver, data processor, programmable signal processor, consoles and controls and displays.

Today, almost all airborne radar antenna system is a flat slit antenna array, Cassegrain antenna, passive or active phased antenna array.

Modern radar systems operate in a range of different frequencies and allow detecting air targets with EPR (Effective dispersion area) of one square meter at a distance of hundreds of kilometers, and also provide support for dozens of targets during the passage.

In addition to target detection, today radar radios provide radio correction, flight mission and target designation for the use of guided airborne weapons, perform mapping of the earth's surface with a resolution of up to one meter, and also solve auxiliary tasks: following the terrain, measuring its own speed, height, drift angle and others .

3. How does an airborne radar work?

Today, modern fighters use pulse-Doppler radar. The title itself describes the principle of operation of such a radar station.

The radar station does not operate continuously, but with periodic shocks — pulses. In today's locators, the sending of an impulse lasts only a few millionths of a second, and the pauses between pulses last a few hundredths or thousandths of a second.

Having encountered any obstacle on the way of their propagation, the radio waves are scattered in all directions and are reflected from it back to the radar station. At the same time, the radar transmitter automatically turns off, and the radio receiver begins to work.

One of the main problems of pulsed radar is to get rid of the signal reflected from fixed objects. For example, for airborne radars, the problem is that the reflection from the earth’s surface obscures all objects lying below the plane. This interference is eliminated using the Doppler effect, according to which the frequency of the wave reflected from an approaching object increases, and from the outgoing object decreases.

4. What do the X, K, Ka and Ku ranges in the characteristics of the radar?

Today, the range of wavelengths in which airborne radar stations operate is extremely wide. In the characteristics of the radar station range is indicated in Latin letters, for example, X, K, Ka or Ku.

For example, the Irbis radar with a passive phased antenna array, mounted on the Su-35 fighter, operates in the X-band. At the same time, the detection range of the Irbis air targets reaches 400 km.

X-band is widely used in radar. It extends from 8 to 12 GHz of the electromagnetic spectrum, that is, these are wavelengths from 3,75 to 2,5, see. Why is it named that way? There is a version that during the Second World War, the range was classified and therefore received the name X-band.

All names of the ranges with the Latin letter K in the name have a less mysterious origin - from the German word kurz ("short"). This range corresponds to the wavelengths from 1,67 to 1,13, see. In combination with the English words above and under, the Ka and Ku bands, which are respectively “above” and “below” the K-band, received their names.

Ka-band radars are capable of operating at short distances and making ultra-high resolution measurements. Such radars are often used to control air traffic at airports, where using very short pulses - a few nanoseconds in length - determine the distance to the aircraft.

Often Ka-band is used in helicopter radar. As is known, for placement on a helicopter, the radar antenna should be small. Given this fact, as well as the need for an acceptable resolution, the millimeter wavelength range is applied. For example, the Ka-52 “Alligator” combat helicopter is equipped with the “Crossbow” radar complex operating in the eight-millimeter Ka-band. This radar developed by KRET provides the Alligator with enormous opportunities.

Thus, each range has its advantages and, depending on the conditions of placement and tasks, the radar station operates in different frequency ranges. For example, obtaining high resolution in the front sector of the review realizes the Ka-band, and increasing the range of the radar makes the X-band possible.

5. What is PAR?

Obviously, in order to receive and emit signals, any radar needs an antenna. To fit it into the plane, they invented special flat antenna systems, and the receiver and transmitter are located behind the antenna. To see different targets with radar, the antenna needs to be moved. Since the radar antenna is massive enough, it moves slowly. At the same time, the simultaneous attack of several targets becomes problematic, because a radar with a conventional antenna keeps only one target in the “field of view”.

Modern electronics has allowed to abandon such a mechanical scan in radar. It is arranged as follows: a flat (rectangular or round) antenna is divided into cells. In each such cell there is a special device - a phase shifter, which can change the phase of an electromagnetic wave that enters the cell at a given angle. The processed signals from the cells arrive at the receiver. This is how you can describe the work of a phased antenna array (PAA).

And more precisely, a similar antenna array with many phase shifters, but with one receiver and one transmitter, is called a passive HEADLAMP. By the way, the world's first fighter equipped with a radar from a passive phased array is our Russian MiG-31. It was installed radar "Barrier" developed by the Research Institute of Instrument Engineering them. Tikhomirov.

6. What is AFAR for?

Active phased array antenna (AFAR) is the next stage in the development of passive. In such an antenna, each cell of the array contains its own transceiver. Their number may exceed one thousand. That is, if a traditional locator is a separate antenna, receiver, transmitter, then in AFAR a receiver with a transmitter and an antenna are “scattered” into modules, each of which contains an antenna slot, a phase shifter, a transmitter and a receiver.

Previously, if, for example, the transmitter failed, the plane became “blind”. If one or two cells, even a dozen, are affected in AFAR, the rest continue to work. This is the key advantage of AFAR. Thanks to the thousands of receivers and transmitters, the reliability and sensitivity of the antenna is increased, and it is also possible to operate at several frequencies at once.

But most importantly, the structure of the AFAR allows the radar to simultaneously solve several problems. For example, not only to serve dozens of targets, but also in parallel with the review of space, it is very effective to defend oneself from interference, interfere with enemy radars and map the surface, getting high-resolution maps.

By the way, Russia's first airborne radar with AFAR was created at the KRET enterprise, at the Fazotron-NIIR corporation.

7. What radar will be on the fifth-generation fighter jet PAK FA?

Among the promising developments of KRET are conformal AFAR that can fit into the fuselage of the aircraft, as well as the so-called "smart" airframe of the airframe. In the next generation of fighters, including the PAK FA, it will become like a unified receiving-transmitting locator, providing the pilot with full information about what is happening around the aircraft.

The PAK FA radar system consists of a perspective X-band AFAR in the nose compartment, two side-view radars, and an L-band AFAR along the flaps.

Today, KRET is also working on the creation of a radiophotonic radar for the PAK FA. The concern intends to create a full-scale model of a radar station of the future before 2018.

Photonic technologies will expand the capabilities of the radar - to reduce the weight more than twice, and increase the resolution capacity tenfold. Such radars with radio-optical phased antenna arrays are capable of making a kind of “X-ray photograph” of airplanes located at a distance of more than 500 kilometers, and give them a detailed, three-dimensional image. This technology allows you to look inside the object, find out what equipment it carries, how many people are in it, and even see their faces.
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  1. Internal combustion engine
    Internal combustion engine 27 February 2016 06: 54 New
    The speed of evolution of radars is simply amazing. And I am glad that our designers are ahead of the whole planet.
    1. Mera joota
      Mera joota 27 February 2016 09: 37 New
      Quote: ICE
      And I am glad that our designers are ahead of the whole planet.

      What is your conclusion based on?
      1. aiw
        aiw 27 February 2016 20: 14 New
        Whose was the first production aircraft with HEADLIGHTS? Who invented the electronic warfare, who is now the leader in the development of electronic warfare? Well, radio photonics is of course the cutting edge ....
      2. Rossiyanin
        Rossiyanin 27 February 2016 23: 43 New
        In the production of the latest and unique technology for the MO and Navy.
  2. The comment was deleted.
  3. afrikanez
    afrikanez 27 February 2016 07: 27 New
    This technology allows you to look inside the object, find out what equipment it carries, how many people are in it, and even make out their faces.
    When you read about this, it seems that he has looked into the future and it is very pleasing. good Now it’s even hard to imagine what a 6th generation aircraft will be like (meaning radar). As they say: wait and see, it remains only to live to this point.
  4. Aaron Zawi
    Aaron Zawi 27 February 2016 09: 18 New
    Great article. Such a public educational program is simply necessary. And then part of the forum participants write this ... request
  5. Fitter65
    Fitter65 27 February 2016 09: 32 New
    decided to place on a double Pe-2.
    The Pe-2 was three seater. The crew consisted of a pilot, a navigator in the front cockpit and a radio gunner located in the rear. The two were local heavy Pe-3 fighter, although it was created on the basis of the Pe-2, but this was not much different the car, with its own differences. Why it was assigned its own index. here on Pe-3 and the first radars were installed, and since the Pe-3 was not satisfactory in its characteristics, later they began to install radars on the A-20 which was supplied to us by lenlysis .And so I liked the article ...
  6. The comment was deleted.
  7. Mountain shooter
    Mountain shooter 27 February 2016 09: 39 New
    AFAR antennas are just some kind of magic, and radio-optical ones are generally at the limit of understanding. The good news is that our radiophysics is quite at the world level, and DOES NOT YET TO "partners" in product quality. On the PAK FA, side-scan antennas (as they say) are built into the skin, the aircraft generally has a circular view. In combination with super-maneuverability and the latest weapons, it is generally a "dragon-thundering", not an airplane. Our hello to the hegemon.
  8. gregor6549
    gregor6549 27 February 2016 13: 17 New
    Quote: afrikanez
    This technology allows you to look inside the object, find out what equipment it carries, how many people are in it, and even make out their faces.

    How can a person who claims knowledge of radio electronics in general and in radar in particular write such nonsense?
    1. aiw
      aiw 27 February 2016 20: 16 New
      Apparently, the author thus wanted to explain about what gives a high resolution.
  9. tchoni
    tchoni 27 February 2016 13: 43 New
    Well, look inside, say, a tank, this is anryl, but radar images and portraits are a reality. They can be used to recognize visible objects.
    1. gregor6549
      gregor6549 27 February 2016 14: 28 New
      Yes, the reality realized in the experiments of 30 years ago. But the question rests on the wavelength. In order to get a distinct r / l image, you need a millimeter wave range, and this range with a range acceptable for aircraft systems is not good friends. Therefore, modern aircraft radars are mainly centimeter range. And in this range, solving the problem of obtaining r / l images with a high level of resolution in real time is very problematic
      1. tchoni
        tchoni 27 February 2016 15: 25 New
        Not in the wavelength, but in the aperture of the antenna array. It is the ratio of the aperture to the wavelength that determines the resolution of the radar. It is no coincidence that in the systems of radar reconnaissance of terrain like the same jistars, aperture synthesis is used for side-scan radars.
        1. gregor6549
          gregor6549 27 February 2016 15: 37 New
          Everything is correct, for the R / L systems of the side view with the synthesized aperture, obtaining a detailed r / l / image of the area is quite possible and has been implemented for a long time. But we are talking about airborne radar fighters and similar aircraft where the aperture of the radar antenna is determined by the cross section of the nose of the fuselage i.e. very small and the wavelength range used in such radars no matter how centimeter. So what r / l / images in such radars are in question, who needs them there and who will deal with them in aerial combat. There, it would be time to simply discover the target, determine its state affiliation and set someone else's target for auto tracking / autocapture, while managing to pilot the plane.
          1. tchoni
            tchoni 27 February 2016 16: 55 New
            Well, how can I tell you ... A modern aircraft needs radars not only in battle, but also in reconnaissance, navigation, and even terrain mapping. In the end, if the radar is conformal (and they promise us in the fifth generation) why not implement these functions of a detailed view of the area with aperture synthesis :-)
          2. sharp-lad
            sharp-lad 27 February 2016 23: 49 New
            As far as I understand, the pilot will receive information summarized by the onboard intelligent system with recommendations for subsequent actions. This is no longer a secret and has long been used on aircraft of previous generations. More detailed information collected during the flight will generate adequate recommendations to the pilot and will help in determining goals and their ranking. And who said that there is enough information about the enemy before, during and after the clash? hi
  10. xam0
    xam0 28 February 2016 00: 37 New
    Many thanks to the author of the article for a rather short, but informative article in which the history, present and future development of the radar station fits.
    I'm not special on them, but I always wondered what was hidden behind the mean ones. radar characteristics of modern aircraft, what distinguishes different types. Now much becomes clear, and many of the modern characteristics of the radar are simply impressive. I hope that in the future our planes will be equipped with the most advanced equipment so that we are always at least one step ahead of our enemies. Thanks again!
    1. gregor6549
      gregor6549 28 February 2016 10: 16 New
      And I want to, but the harsh reality is that in terms of radar, we, often ahead of the West in technical ideas, as a rule were behind in terms of their implementation. And above all, because of the constant lag in the development and production of the element base. And without it, the most beautiful idea cannot be realized. Of course, through incredible tricks, domestic designers managed to provide the main performance characteristics of airborne radars comparable to their western counterparts, except for overall dimensions, but they also had to pay for this with a reduction in fuel supply, and a reduction in ammunition stock, etc. And if in terrestrial systems the element base problem was solved relatively harshly just (for example, by introducing into the system a pair of three additional mobile units, then, unfortunately, you won’t fasten the trailer to the fighter.