This article focuses on developing adaptive detectors for radar targets in nonhomogeneous and non-Gaussian sea clutter. The non-Gaussian characteristics are captured through the compound Gaussian representation with Nakagami-distributed texture components and an unspecified speckle covariance structure. To improve detection reliability when facing limited training samples in nonhomogeneous environments, the speckle covariance matrix is modeled with persymmetric constraints, thereby reducing training data dependence. The received radar data are first transformed through the property of the persymmetric matrix and vector. Based on two-step suboptimal test frameworks (including generalized likelihood ratio, Wald, Rao, Durbin, and Gradient tests) and analytical mathematical expressions for estimating clutter parameters, we develop persymmetric adaptive coherent detectors for radar target detection in compound Gaussian clutter with Nakagami-distributed texture. Notably, the test statistics derived from the two-step Gradient, Durbin, and Rao tests are shown to be identical. Experimental results employing both simulated and measured radar datasets demonstrate the superior performance of the proposed detectors relative to conventional methods.
The data to be processed in near-field three-dimensional (3D) imaging is of a considerable volume. The interpolation operation is both time-consuming and introduces interpolation errors, which considerably degrade both accuracy of the imaging and the efficiency of the computing. In order to address these challenges, this paper presents a rapid algorithm for millimeter-wave near-field 3D image reconstruction based on the Flatiron Institute nonuniform fast Fourier transform (FiNUFFT). The presented algorithm replaces the traditional Stolt interpolation method and the subsequent inverse fast Fourier transform (IFFT) in the corresponding dimension with FiNUFFT. This results in a notable reduction in the computational burden, a decrease in processing time, and the circumvention of the interpolation error introduced by the Stolt interpolation. The proposed algorithm is designed to ensure the reconstruction of high-quality 3D images, with the potential to significantly enhance the efficiency of computation. This provides a more efficient and accurate solution for millimeter-wave near-field 3D imaging. The effectiveness of the proposed algorithm has been validated through simulations and real data experiments.
The electronic interception system requires capturing a sufficiently long and relevant pulse traffic to determine the presence of a radiation source. This paper originates from active countermeasures perspectives and introduces a multi-radar resource allocation scheme in multi-target tracking scenarios to counteract pulse deinterleaving. Our study aims to enhance radar network stealth while preserving tracking accuracy by leveraging the collaborative capabilities of networked radars. We establish and analyze the signal model of multiple co-located multiple input multiple output radars tracking multiple targets and find that radar-controllable variables such as radiation power, duty cycle, and dwell time can impact both tracking precision and interceptable pulse length by interception receivers. Unlike conventional radar radio frequency stealth methods focused solely on single-pulse detection, we optimize these variables to reduce both probabilities of individual pulse interception and pulse traffic deinterleaving or sorting, lowering overall radar interception risks. Simulation results confirm the efficacy of our methodology in bolstering radar network resilience against reconnaissance threats while maintaining robust target detection capabilities. This research underscores the importance of optimizing radar resource management strategies to achieve a balanced trade-off between detection performance and stealth capability in practical deployment scenarios.
Frequency-selective rasorber (FSR) is a new electromagnetic metamaterial which is proposed in recent years. In this paper, a FSR with two absorption bands is designed. It consists of two layers and air space between them. Based on the LC equivalent circuit, the FSR has a passband at 10.3GHz with 0.26dB insertion loss. The refection coefficient below -10dB is from 6.6GHz to 24.1GHz. The relative bandwidth is 114%. The absorption rate over 80% covers frequency band from 6.6GHz9.2GHz and 13.2GHz-25GHz.
This paper proposes a standardized method for counter-interference algorithms in testbeds, aiming to provide a high-fidelity validation platform for radar counter-interference algorithms. By constructing a testbed that simulates pursuit-evasion scenarios, the system model, observation model, and predicted state output are defined, achieving algorithm standardization. The paper details the modular design of the algorithm, including eight modules such as initialization, prediction, and update, and defines the inputoutput interfaces for each module. Experimental results show that the standardized algorithm can accurately track targets and successfully identify both targets and decoys on the DSP platform, with minimal angle errors. This research provides an efficient and scientific validation platform for the development and optimization of counter-interference algorithms.
