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Radar Electronic Warfare
Published in Habibur Rahman, Fundamental Principles of Radar, 2019
Electronic countermeasures (ECM): ECM is that division of electronic warfare involving actions taken to prevent or reduce an enemy's effective use of the electromagnetic spectrum. ECM itself consists of two types. The first is jamming (sometimes called denial ECM)—where an electromagnetic signal provides so much jamming signal that the radar's signal processor and displays are occupied almost totally with the jamming to the exclusion of the targets. The second, called deception, is where emitted ECM signals are meant to simulate or imitate desired signals, but with changes, or are meant to manipulate the system into reporting. Essentially, deceptive jamming attempts to fool the radar into reporting targets at the wrong range, or wrong Doppler, or wrong angles. Manipulative ECM attempts to induce actions on the part of its victim that are detrimental to the victim's well-being. Simulative ECM makes an excellent radar design tool, and provides radar performance assessment. Digital techniques are widely used for ECM simulation.
The Radar Equation
Published in Bassem R. Mahafza, Introduction to Radar Analysis, 2017
Any deliberate electronic effort intended to disturb normal radar operations is usually referred to as an Electronic Countermeasure (ECM). This includes chaff, radar decoys, radar RCS alterations (e.g., radio frequency absorbing materials), and of course, radar jamming. Jammers can be categorized into two general types: (1) barrage jammers and (2) deceptive jammers (repeaters). When strong jamming is present, detection capability is determined by receiver signal-to-noise plus interference ratio rather than SNR. In fact, in most cases, detection is established based on the signal-to-interference ratio alone.
Terahertz reconfigurable multi-functional metamaterials based on 3D printed mortise-tenon structures
Published in Virtual and Physical Prototyping, 2023
Bo Yu, Lesiqi Yin, Peng Wang, Cheng Gong
Therefore, there is still a lack of terahertz multi-functional materials that can be easily produced and regulated. In the previous work, we proposed a terahertz multi-functional metamaterial based on nano-imprinting technology, which can simultaneously achieve broadband absorption and narrowband transmission (Li et al. 2023). Further, we propose another terahertz multi-functional metamaterials based on mortise and tenon mechanism, which could realise not only the functions of transmission-absorption, but also the switchable functions of reflection-absorption and prefect reflection, as shown in Figure 1: (I) Narrowband transmission and broadband absorption are achieved by structure A; (II) Perfect reflection is achieved by the combination of structure A + B; (III) Narrowband reflection and broadband absorption are achieved by the combination of structure A + C. The combination of mortise and tenon structures based on three-dimensional geometric complementarity can quickly and easily switch between the above multiple functions. Moreover, the hybrid 3D printing process combining FDM and E-jet printing can greatly simplify the fabrication process, improve speed, and reduce costs. This kind of multi-functional terahertz metamaterials is expected to be applied to large-scale electromagnetic shielding, radar stealth, electronic countermeasures, and other fields.
On Fixed-Width Confidence Limits for the Risk Ratio with Sequential Sampling
Published in American Journal of Mathematical and Management Sciences, 2020
In military operations, it is very crucial to know whether implementing an electronic jamming technique or device, called the electronic countermeasures (ECM), in radar/sonar detection of airborne/underwater objects is effective in reducing the lethality or not. For this we consider the measure of reduction in the effectiveness of airborne/underwater electronic countermeasures, and the effectiveness is measured by comparing the proportions or numbers of hits under two conditions (dry/wet) whether ECM is turned on or off. An airborne/underwater object is said to be in a dry condition when ECM is turned off and in a wet condition when ECM is turned on. For instance, most air forces use ECM to protect their aircraft from being shot. In regards to the ECM, the measure of reduction in risk (RIR) in Table 5 is called the reduction in lethality (RIL).
An adaptive filtering algorithm in pulse-Doppler radar for counteracting range-velocity jamming
Published in International Journal of Electronics, 2022
Ahmed Abdalla, Mohammed Ramadan, Yongjian Liao, Shijie Zhou
Radars are active devices, which use their radio energies to detect the wanted targets. They do not depend on energies that are radiated from the targets themselves. Therefore, in a hostile environment, radar is likely to be subjected to the electronic countermeasures (ECM) to avoid target detection and classification (Wen et al., 2019; H. Yu et al., 2020). ECM system or jammer is usually employed to deny or degrade the ability of the radar system to maintain its mission (Abdalla, Yuan, Longdon et al., 2015). In such situations, the radar will attempt to perform its purpose without being influenced by this attack, which leads to the creation of electronic warfare (EW) (Maini, 2018). ECM and electronic counter-countermeasures (ECCM) form the principal conflicting pair in modern electronic warfare (Abdalla et al., 2017; Haykin, 2006). By the mean of precise replication and reproduction of the radar signal through the digital radio frequency memory (DRFM), the modern deception ECM has entered an area of coherent false targets. From the point view of the radar, such false targets can easily obtain radar coherent processing gain, such that they are capable of affecting or even screen the detection and extraction of true targets stealthily (Berger, 2003; Bokov et al., 2019; W. Liu et al., 2019; Mesarcik et al., 2019; G. Zhang et al., 2019). Moreover, the pressed parameters extracted by subsequent processes can further consume the resources of radar and protect true targets, and as a result, an error decision may be made about the current target or air intelligence. It is a powerful technology measure to counter various types of radars, especially advanced radar systems.