In this paper, an ultra-wideband (UWB) microwave absorber with robust angular stability is proposed. Each unit of the structure consists of three-layer stacked resistive films to effectively broaden the absorption bandwidth. A metallic via is inserted in the center of the structure, which effectively guides the TM polarization oblique incident wave power to propagate vertically and be absorbed by the resistive films, thus enhancing the angular stability of TM polarization. Within the frequency range of 3.2 GHz to 35.5 GHz, the absorptivity surpasses 90% and the fractional bandwidth reaches 167%. Within an incident angle range of 0∘ to 60∘, the absorptivity of TE polarization remains at about 80%, and the TM polarization can be maintained at over 90%. The absorption mechanism was analyzed by surface power loss and surface current distribution. A sample was fabricated, and the measured results are consistent with the simulated ones. The absorber displays good angular stability and broad bandwidth, making it ideal for electromagnetic stealth applications.

An algorithm to track multiple sharply maneuvering targets without prior knowledge about new target birth is proposed. These targets are capable of achieving sharp maneuvers within a short period of time, such as drones and agile missiles. The probability hypothesis density (PHD) filter, which propagates only the first-order statistical moment of the full target posterior, has been shown to be a computationally efficient solution to multitarget tracking problems. However, the standard PHD filter operates on the single dynamic model and requires prior information about target birth distribution, which leads to many limitations in terms of practical applications. In this paper, we introduce a nonzero mean, white noise turn rate dynamic model and generalize jump Markov systems to multitarget case to accommodate sharply maneuvering dynamics. Moreover, to adaptively estimate newborn targets' information, a measurement-driven method based on the recursive random sampling consensus (RANSAC) algorithm is proposed. Simulation results demonstrate that the proposed method achieves significant improvement in tracking multiple sharply maneuvering targets with adaptive birth estimation.

This paper addresses a pursuer tracking problem where the pursuer's acceleration is given by a proportional navigation (PN) guidance law with a time-varying navigation ratio which varies with the relative range between the pursuer and its target. Based on a motion model that exactly describes the relative motion and the PN guidance law, a novel filter for tracking such a pursuer is designed using interactive multiple model (IMM) algorithm and unscented Kalman filtering (UKF) technique. This filter is able to accurately estimate the relative range, relative velocity, and the acceleration of pursuer even if the pursuer adopts a PN guidance law with time-varying navigation ratio. The proposed tracking method is evaluated in extensive Monte Carlo simulations. It is shown that accurate estimation results have been obtained, and the model probabilities in the IMM UKF filter are consistent with real situations.

Identifying the aim of the pursuer accurately and timely is vital for evader taking appropriate countermeasures to avoid capture successfully. In order to determine whether the evader in a flying formation is aimed by the pursuer or not, an aim identification algorithm is proposed based on the stationarity difference of the mixed product of three direction vectors, i.e., the evader's velocity vector and the evader-to-pursuer line of sight (LOS) vector at the same instant as well as another such LOS vector at a subsequent instant. Due to the effect of the guidance law, the subsequent LOS always shows a tendency to keep coplanar with the velocity of the aim and the previous LOS such that the mixed product obtained by the aim changes very slowly. In another word, the mixed product sequence obtained by the aim based on the known velocity and the bearing measurements of the LOS has relatively good stationarity while the stationarity of the sequence obtained by the evader not being aimed at is poor. Based on the stationarity difference, the mixed product sequences are used to formulate a chi-square distributed statistic such that the aim identification is equivalently transformed into a hypothesis testing problem. Simulation results are given to verify the effectiveness of the proposed algorithm.

The paper proposes an ultra-wideband frequency selective rasorber (FSR) with low infrared emissivity for the composite detection threat of both radars and infrared sensors. Firstly, the equivalent circuit (EC) method based on transmission line (TL) theory is utilized to analyze the absorption/transmission conditions. Then, based on the analysis above, sinusoidal microstrip lines with non-frequency-varying characteristics are adopted in the design, which significantly enhances the transmission bandwidth of FSR. The FSR demonstrates an absorption band ranging from 2.65 GHz to 8.80 GHz and a transmission band ranging from 9.15 GHz to 17.71 GHz. Furthermore, an infrared shielding layer (IRSL) exhibiting low emissivity in the infrared band and high transmittance in the microwave band is applied to the FSR. The simulation and experiment results verify that the IRSL-FSR demonstrates an ultra-wide transmission band ranging from 9.16 GHz to 17.94 GHz and an ultra-wide absorption band ranging from 2.66 GHz to 8.01 GHz. Additionally, it exhibits a low emissivity value (0.23) in 8–14 μm, providing a viable solution to the formidable challenge of radar-infrared bistealth for satellites and other communication-enabled flying platforms.

针对隐身目标低频超宽带电磁吸收的需求，提出了一种基于多机制协同的设计方法，通过结合磁性材料和阻性表面的损耗特性，并联合等效电路模型和遗传算法进行快速阻抗匹配和参数优化，实现P-Ku 波段低频宽带吸波体设计。本文理论分析了磁性材料降低吸波体厚度和提升低频吸波性能的机制，通过磁性材料和阻性表面协同设计，实现P-L 频段内优异吸波效果。进而，通过多层阻性表面级联结构补偿S-Ku 波段内的吸波性能，实现P-Ku 超宽带高性能吸波体设计。设计的低频 超宽带吸波体在0.3-0.33 GHz 和0.33-18 GHz 内分别实现至少-8 dB 和-10 dB 的反射损耗，厚度仅为0.027λL(λL 为最低频率处的波长)。同时，该吸波体具有大角度稳定性，在45°TE 波和60°TM波斜入射下依然保持良好的吸波性能。最后，进行了加工和实验测试，结果表明该吸波体具有低频宽带吸波性能以及宽角度稳定特性。