Introducing today's airborne radars

Basically all types of radar can be found on fighter aircraft

(1) According to the method of positioning can be divided into: active radar, semi-active radar and passive radar.

(2) According to the location of installation can be divided into; ground radar, shipboard radar, aviation radar, satellite radar and so on.

(3) According to the type of radiation can be divided into: pulse radar and continuous wave radar.

(4) According to the working wavelength band can be divided into: meter wave radar, sub-meter wave radar, centimeter wave radar and other wave band radar.

(5) According to the use can be divided into: target detection radar, reconnaissance radar, weapons control radar, flight protection radar, meteorological radar, navigation radar and so on.

Phased array radar is a new type of active electric sweep array multifunctional radar. It not only has the function of traditional radar, but also has other radio frequency functions. The most important feature of the active swept array is the ability to directly radiate and receive RF energy into the air.

But the above various radar although the specific use and structure is not the same, but the basic form is the same

Radar or rely on the wavelength to distinguish between the various wavelengths of the radar I say the advantages and disadvantages of the various wavelengths of the radar:

Ultra-long-wave radar

Ultra-long-wave radar due to its long wavelength, signal attenuation is small, the propagation distance is long, the positioning accuracy is not high and so on, generally used for Strategic alert. For example, the early warning of intercontinental or medium-range strategic missiles. This kind of radar is a kind of radar that developed relatively fast during the Cold War.

Long-wave (meter-wave) radar

Long-wave (meter-wave) radar is generally used for battle-level airborne alert and air combat guidance. This type of radar concentrates some of the advantages of microwave radar and long-wave radar, has a larger range of action and higher positioning accuracy, and is able to meet the requirements of battle-level airborne alert and guidance.

Microwave radar also has a little-known feature that is very effective against stealth aircraft similar to the United States. This has to do with the design ideology of stealth airplanes. Stealth aircraft are generally designed to achieve stealth by absorbing radar waves, reducing radar angular reflective surfaces, and scattering radar waves. However, the appropriate wavelength radar precisely with the electric wave is absorbed by the low rate, not easy to scatter and other characteristics. Therefore, the meter wave radar is still very effective for stealth aircraft.

Millimeter-wave radar

Usually millimeter-wave refers to electromagnetic waves in the frequency domain of 30 to 300 GHz (wavelength of 1 to 10 mm). The wavelength of millimeter wave is between centimeter wave and light wave, so millimeter wave radar guidance has the advantages of both microwave guidance and photoelectric guidance. Compared with centimeter-wave guides, millimeter-wave guides are characterized by small size, light weight and high spatial resolution. Compared with infrared, laser, television and other optical guide, millimeter-wave guide penetrates fog, smoke, dust, with all-weather (except heavy rain) all-weather characteristics. In addition, millimeter-wave guide head anti-jamming, anti-stealth capabilities are also better than other microwave guide head. In recent years, with the development of computer technology, millimeter-wave solid-state technology, signal processing technology, optoelectronics technology and materials, devices, structures, processes, solid ****-shaped phased array antennas and millimeter-wave integrated circuits technology and other related technologies have been successfully applied to the millimeter-wave guide head performance has been improved to lay a good foundation.

One of the key technologies of millimeter-wave guide head is antenna technology. Commonly used millimeter-wave radar antennas are as follows: reflective surface antenna, lens antenna, horn antenna, dielectric antenna, leaky wave antenna, microstrip antenna, phased array antenna and so on.

That depends on what conditions are categorized according to

In accordance with the technology used by the radar and the way the signal is processed there are: pulse Doppler radar, synthetic aperture radar, scanning and tracking radar.

Categorized according to the antenna scanning method, is divided into mechanical scanning radar, phased array radar and so on.

The phased array radar is also divided into: active phased array radar and passive phased array radar

According to the structure is also divided into: full electric scanning phased array and limited electric scanning phased array.

Pulse Doppler radar: such as the U.S. active F-14, F-15, F / A-18 and F-16 and other fighters were equipped with AWG-9, APG-63, APG-65 and APG-66A / B, APG-68C / D and other radars. (Advantages) A narrow-band filter that coherently accumulates a column of echo pulses from which the Doppler spectral lines of the target are selected. Pulse Doppler radar of this signal processing can be obtained near-optimal signal power to clutter plus noise power ratio, and more accurate target distance and radial velocity data. (Disadvantage) Pulsed Doppler radar employs a sufficiently high pulse repetition frequency (usually above 20 kHz), but this brings with it a very close maximum range for the radar to measure target distance, and the appearance of target echoes at long distances across the cycle blurs the distance to the target. In addition, the high pulse repetition frequency makes the clutter at different distances superimposed, the clutter intensity increases greatly, increasing the difficulty of suppressing the clutter, and thus puts forward higher requirements on the performance of the radar.

Synthetic aperture radar: characterized by high resolution, can work all-weather, can effectively identify camouflage and penetrate the cover. The disadvantages are small coverage area and long scanning period.

Scanning-while-tracking radar: Taking the F-14's AWG-9 as an example, it is capable of tracking 24 dispersed targets at the same time. Directs six Adena missiles on a time-separated basis to six dispersed targets almost simultaneously (within 2 seconds). No drawbacks have been identified for this type of radar.

Mechanically scanned radar: the vast majority of today's fighters are equipped with this type of radar from its inception to the present day. (Disadvantages) Mechanical equipment, which is about half the cost of a complete mechanical radar system, is the most prone to all kinds of malfunctions, accounting for the vast majority of radar system malfunctions, and requires daily maintenance. In addition, the mechanical equipment limits almost all the basic performance of the radar system, including the line of detection, interception of the tracked target, protection against various types of interference, communication capacity, and so on.

Phased-array radar: the type of radar that is emerging with many advantages.

(1) flexible beam pointing, can realize inertia-free fast scanning, high data rate;

(2) a radar can form multiple independent beams at the same time, respectively, to realize the search, identification, tracking, guidance, passive detection, and other functions;

(3) large target capacity, can be in the airspace at the same time monitoring and tracking of hundreds of targets;

(4) adaptability of complex target environments;

(4) on the adaptability to complex target environment;

(5) good anti-jamming performance. All-solid-state phased array radar is highly reliable, even if a small number of component failure can still work normally.

Disadvantages also: phased array radar equipment is complex, expensive, and the beam scanning range is limited, the maximum scanning angle of 90 ° ~ 120 °. When the need for omni-directional surveillance, the need to configure 3 to 4 antenna array.

Active phased array radar each radiator is equipped with a transmitter/receiver components, each component can generate its own, receive electromagnetic waves, so in the frequency bandwidth, signal processing and redundancy design than passive phased array radar has a greater advantage. Because of this, it also makes active phased array radar expensive and difficult to engineer. But active phased array radar has unique advantages in function, there is a trend to replace passive phased array radar.

Active and passive phased array radar antenna array is the same, the main difference between the two is the number of transmitting/receiving elements.

The biggest difficulty in active phased array radar lies in the manufacturing of the transmit/receive elements, while passive phased array radar is comparatively much less technically difficult. Passive phased array radar is not as good as active phased array radar in terms of power, efficiency, beam control and reliability, but functionally it is significantly better than ordinary mechanically scanned radar, which is a better compromise program. Therefore, before the development of a practical active phased array radar, it is possible to use passive phased array radar as a transitional product. Moreover, even after the successful development of active phased array radar, passive phased array radar as a phased array radar family of low-end products, still has great practical value.

All-electro-sweep phased array and limited electro-sweep phased array: all-electro-sweep phased array can also be called fixed phased array, that is, in the azimuth and elevation are used in the electro-sweep, the antenna array is fixed and immobile. Limited electric sweep phased array is a hybrid design antenna, that is, more than two kinds of antenna technology combined to obtain the required effect, at first the phase sweep technology and reflective surface antenna technology, its electric sweep angle is small, only a small number of radiation unit, so can greatly reduce the equipment cost and complexity.

Nowadays, radar tends to be multi-functional, often a radar inherited more than one category of radar characteristics, so the "radar type" becomes "radar function".

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