Radar - Modern Stealth Technology in Electronic Warfare
After the 21st century, the development of stealth technology has promoted the intensification of competition among various countries in weapons and equipment, the development of stealth technology, and the improvement of the survival, air defense and in-depth strike capabilities of weapon systems. It has become a five-dimensional integration of land, sea, air, sky, and electromagnetic. The urgent need for modern warfare. Stealth technology and Star Wars and nuclear technology have been listed by the United States as three major high-tech fields for national defense. The realization of the stealth of radar waves and the reduction or loss of detection capabilities of enemy radars has caused great concern in various countries. The essence of radar stealth is to make it impossible for an enemy radar to accurately detect the target echo signal. The Radar Cross Section (RCS) of the target characterizes the echo signal amplitude returned by the target to the radar. Therefore, to achieve radar stealth, the core is to reduce the target RCS. Radar maximum working distance equation: It can be known from the formula that the fourth power of the radar detection distance Rmax is proportional to the target's scattering cross-sectional area σ. To reduce the radar detection range, the target's own RCS must be reduced. Reducing the target RCS essence is to reduce the target echo power or the scattered wave electric field strength. RCS has nothing to do with the irradiation power and the distance of the aircraft from the radar. It is only related to the target's surface conductivity characteristics, structure, material, body shape and attitude angle. Therefore, radar stealth can be achieved by changing the shape, material structure, and electromagnetic characteristics of the target. There are usually two ways to achieve this: First, the use of shape design, absorbing or wave-transmitting materials, etc., to reduce the reflected power; Second, produce a field that is coherent with the scattered field but the opposite phase, to achieve a (none) source cancellation. Radar Stealth Technology Radar Stealth Technology is a technique that achieves stealth by reducing the target RCS. Commonly used methods include shape stealth technology, material stealth technology, electronic interference and deception technology, and impedance loading technology. 1, shape stealth technology Shape design is the most direct and effective way to achieve weapon stealth. The essence of the shape stealth technology is to convert the strong reflection source of the target into a weak reflection source, that is, by changing the shape design of the target, enhancing the reflection or refraction effect of the target within a certain angle and reducing the RCS. Common sources of strong reflections are the aircraft's edge, tip, projections, and attachments on the body; the missile's head, tail, and airfoil are not connected; the ship's hull and deck edges. The US AGM-129 Stealth Cruise Missile eliminates strong reflection sources by using special stealth shapes and stealth structures, which reduces the scattering intensity of radar waves. 2. Material Stealth Technology Since the target is limited by factors such as aerodynamics, the exterior design can only achieve certain degree of stealth on the equipment. Material stealth technology can effectively make up for its deficiencies. Material stealth technology can be divided into three types according to the working principle: First, after the material absorbs radar waves, it converts electromagnetic energy into heat energy and dissipates it in a way of energy loss; Second, it quickly disperses the radar wave to the whole body of the equipment, reducing the scattering of the target. The strength of the electric field; the third is to realize passive cancellation by superimposing reflection waves on the upper and lower surfaces of the material. Absorber materials are generally classified into a paint type and a structure type: A paint type is applied to a target surface to form a wave-absorbing coating, and a structural type is a composite material that participates in the structural load-bearing capacity. The wave-transparent material can transmit radar waves almost completely, thereby reducing the target RCS. According to reports, the F-117A Stealth fighter has used a large number of stealth methods, such as polyhedral shape design and radar absorbing materials. Its RCS has been reduced by 23 dB compared with conventional fighters, and the conventional radar range has been reduced by 73%. 3, electronic interference and deception techniques The essence of electronic interference technology is to generate a characteristic signal similar to the target or enemy radar, making it impossible to make correct judgments and achieve target stealth. Common technical means include: placing jamming objects such as chaffs in the air to form interference layers to cover real objects; using electronic jamming equipment to emit noise or similar noise interference signals so that enemy radar cannot detect target information; detected by the reconnaissance equipment The enemy radar frequency, and the use of this frequency to launch echo pulses, so that the enemy radar can not make a correct decision; Using false targets or radar decoy technology, sending false signals to mislead the enemy. According to reports, the United States is investigating a new type of bait capable of emitting high-frequency (VHF), ultra-high frequency (UHF) and microwave signals, which can also mimic stealthy aircraft targets. 4, impedance loading technology Impedance loading can be divided into passive impedance loading and active impedance loading. Passive impedance loading is to change the current distribution on the surface of the skin by forming gaps, cavities, or passive arrays with periodic structures on the surface of the aircraft, thereby reducing electromagnetic scattering within a certain range of angles. Active impedance loading refers to the installation of transponder and other signal processing components on the aircraft so that it can emit electromagnetic waves with similar amplitude and opposite phase to the incident radar wave, so that the target scattered field and radar radiation field are coherent in the detection direction of the enemy radar. Consumers. Radar Stealth Technology Performance Analysis The great value of radar stealth technology has led to the emergence and development of radar anti-stealth technology. Recognizing and improving the performance defects of radar stealth platforms has become the main direction for the development of stealth weapons in various countries. The RCS values ​​observed for different radar detection angles are quite different: The RCS of the aircraft or missile head or warhead is the smallest due to the optimization of the shape design and the application of new materials; the RCS on both sides and tail is larger because The side wing or wing edge scattering enhancement and vertical tail mirror reflection, infrared radiation, etc.; its maximum RCS gap of 30 dB, indicating that the stealth platform can only achieve part of the airspace stealth. Distribution of F-22 RCS Currently, there are flaws in radar wave stealth weapons and anti-stealth techniques to deal with: 1. Stealth airspace is small: Stealth weapons cannot achieve full airspace and all-round stealth. The RCS of the target is relatively large when viewed from different angles when looking down or looking up. Radar networking technology and early warning aircraft detection technology can be used to achieve anti-stealth. 2. Invisible frequency bands: The general stealth weapons are mainly for centimeter-band radars, and the frequency bands are relatively single. It is impossible to achieve stealth on the entire frequency band. Mibo radar, millimeter-wave radar, over-the-horizon radar, etc. can be used to achieve anti-stealth. 3, high infrared radiation: Stealth weapons due to high-speed motion requires strong power support, the engine's tail nozzle due to a large number of high-temperature air injection and infrared radiation, reducing its stealth performance. Lidar can be used to achieve anti-stealth. 4. Many communication signals: Stealth weapons need to maintain communication with the command and control system and supporting equipment, and a large number of communication signals can easily expose themselves. Passive radio frequency detection systems can be used to achieve anti-stealth. Radar Stealth Technology Development Trend 1, the development of full-wave stealth technology All-band stealth is gradually realized by continuously increasing stealth bands such as laser, visible light, infrared, and radar waves. At present, radar stealth technology is mainly used for centimeter wave radar. However, the development of anti-stealth radar technology has promoted the widespread application of multi-band radars such as meter radar, laser radar, and infrared radar. Therefore, the realization of full-wavelength stealth of equipment is becoming more and more important. The multi-band stealth materials developed by the United States, Germany, and Sweden have reached the four-stage compatibility of visible light, near infrared, mid-far infrared, and radar millimeter wave. It is said that the fifth-generation fighter jets of the United States will use stealth-based stealth technology with better stealth effects. 2. Research and development of new materials At present, composite materials, nanomaterials and smart materials have become an important research direction for radar stealth materials. 1) Composite material is a new type of material made up of several layers of stealth materials with different functions. Generally, the upper layer is a stealthy coating and the lower layer is a radar absorbing material. In recent years, composite materials have continued to develop in the direction of combining the multi-layer method and the homogeneous method. According to reports, a broad-band microwave absorbing material composed of a binder and a nanoscale micro-filler material has been successfully developed in France, and has good wave-absorbing performance in a frequency range of 50 MHz to 50 GHz. 2) Nanomaterials are materials whose feature size is in the nanometer range. Due to its unique structure and excellent wave-absorbing characteristics, this material is characterized by high absorption, thin coating, light weight, wide frequency band absorption, and compatibility with infrared microwave absorption. It is a stealth material with a bright future. At present, this technology has been highly valued by military powers such as the United States, France and Britain. According to reports, ultra-dark powder nano materials developed in the United States have a 99% absorption rate for radar waves. 3) The smart material can automatically adjust the electromagnetic wave and optical characteristics of the weapon by sensing and analyzing the enemy radar detection signal to achieve target stealth. The U.S. Air Force proposed linking multilayer films with different conductivity to obtain a skin structure that is functionally similar to a layered dielectric wave absorbing coating, and embeds various onboard electronic devices, sensors, etc. into the skin to replace The traditional radar antenna forms an intelligent skin. 3, the development of plasma stealth technology The plasma stealth technology essentially achieves target stealth through the reflection and attenuation effects when an incident radar wave acts on the plasma: that is, when the radar frequency is less than the plasma frequency, reflection effects occur, and the radar display can only display false target information; when the radar When the frequency is higher than the plasma frequency, the radar wave absorbs and decays into the plasma, which in turn reduces the target RCS. According to reports, the plasma stealth products of the previous two generations of Russians (the third generation have been used for the T50 fighter) have already conducted flight and ground tests, which can reduce the probability of radar detection by 99%. 4. Development of Radio Frequency Stealth Technology The radio frequency stealth technology refers to the stealth technology that airborne radar, data link and other airborne electronic countermeasure equipments resist passive detection, tracking and identification of the enemy's radio frequency. In the modern warfare, the enemy electronic detection system can obtain electromagnetic radiation signals from our stealth platform radars, communications and other transmitters, and use frequency measurement and direction finding, positioning, signal recognition and other processing methods to obtain our identity attributes and geographical attributes. , such as the relevant parameters of the radiation source, type, spatial location, etc. Therefore, the development of radio frequency stealth technology for the enemy's radio frequency detection system has become an extremely important factor in the design of modern stealth weapons. According to reports, the F-22 is equipped with an APG-77 radar with good RF stealth capability, and the F-35 employs a multi-functional advanced data link system with low intercept probability and low probability of detection. 5050 Rgb Color Strip ,Color Changing Strip Lights,Colored Led Light Strips,Multi Color Led Strip Lights NINGBO SENTU ART AND CRAFT CO.,LTD. , https://www.lightworld-sentu.com
