Micro-Doppler characteristics have been widely utilized to discriminate the space targets. In this paper, the micro-Doppler parametric model (mDPM) is presented to fit the micro-Doppler characteristics of cone-shaped space targets. Then, the genetic algorithm-general parameterized time-frequency transform (GA-GPTF) method is proposed to estimate the parameters of mDPM accurately. Additionally, the ratio of the two parameters of mDPM is verified to be directly related to the physical attribute of scattering centers. It can be applied to discriminate the type of scattering centers quantitatively. Finally, the electromagnetic simulation and anechoic chamber experiment verify the accuracy of mDPM and the effectiveness of the scattering center discrimination method.

A synthetic aperture radar (SAR) image transform method is proposed based on random period amplitude and frequency shifting joint modulation. The random period amplitude sequence is designed to modulate the radar pulse signal so that the sidelobe of range profile is disordered with high level. Based on the spectrum property of random period amplitude sequence, the frequency shifting value can be obtained to conduct the joint modulation. Subsequently, frequency shifting is applied to move the high level sidelobe of range profile to the position of the target of interest (TOI). As a result, the TOI can be protected and false target image emerges, which shows both blanket and deception properties. By utilizing the joint modulation in fast time and amplitude modulation in slow time, the image of TOI is covered after SAR imaging. At the same time, the false images are generated in range and azimuth directions. Finally, simulations and SAR data experiments are conducted to obtain the transformed SAR image with proper amplitude sequence and frequency shifting parameters. The correlation coefficient between the transformed image and real target image is calculated, which indicates the validity of the proposed method.

The time-varying Phase-Switched Screen (PSS) has demonstrated significant potential for modulating radar target features, owing to its exceptional capabilities in harmonic generation and control. However, most existing studies focus on single-dimensional target features, with limited investigation into joint modulation of two-dimensional or higher-dimensional features. In this article, a time-domain digital coding PSS system is proposed. By applying 1-bit periodic phase modulation, the spectral energy of the incident electromagnetic wave is redistributed across multiple harmonics, thereby simultaneously influencing the detection of range and velocity features by linear frequency modulated (LFM) pulse-Doppler (PD) radar. Through precise control of the energy and frequency-domain distribution of these harmonics, radar false targets exhibiting coupled range-velocity features can be synthesized in the feature space. Leveraging this coupling characteristic, the method enables flexible feature modulation, including electromagnetic cloaking, range modulation, Doppler modulation, and range-Doppler two-dimensional joint modulation. Simulations demonstrate the effectiveness of the approach, revealing that the primary false targets remain detectable even at low signal-to-noise ratios (SNR), despite a reduction in the number of the effective false targets. Finally, a practical counter-measure experiment conducted in a microwave anechoic chamber further validates the feasibility and effectiveness of the proposed method.

When a pulse radar signal is implemented in a range-limited anechoic chamber for radar measurement, the transmitted and reflected signal will be coupled at the receiver. To solve this problem and equivalently simulate the whole process of pulse radar measurement in an anechoic chamber, the interrupted transmitting and receiving method is proposed in this letter based on interrupted sampling. The constraints of the transmitting and receiving parameters are deduced with the sizes of the anechoic chamber and target. The pulse compression of the proposed method is performed. Then, the window function is applied to extract the main peaks after pulse compression. Both the simulation and experimental results are provided to demonstrate the effectiveness of the proposed method in overcoming the coupling between the transmitted and reflected pulse signals.

Target probing based on wideband pulse radar is a challenging task for radio frequency simulation (RFS) in anechoic chamber. Due to the long time duration of pulse radar signal and the limited space of anechoic chamber, the reflected signal returns before the pulse radar signal is fully transmitted, which makes it difficult for the signal reception. As a consequence, the target high-resolution range profile (HRRP) cannot be obtained for target imaging and recognition. In this paper, we propose a novel strategy that contains two steps to solve this problem and obtain the target HRRP. First, the randomly interrupted transmitting and receiving (R-ITR) method is proposed to receive the pulse radar signal in RFS. Second, the target HRRP is reconstructed by compressive sensing (CS) since the R-ITR echo is piecewise sparse. The protocol to choose R-ITR parameters and performance of HRRP reconstruction are provided. Simulations and experiments with different R-ITR parameters are also conducted to verify the effectiveness of the proposed method.

Linear frequency modulation (LFM) signal is widely applied in imaging radar including synthetic aperture radar (SAR) and inverse SAR (ISAR). Jamming techniques against LFM imaging radar develop rapidly in the past decades, which make radar imaging with LFM signal to face a great challenge. In this paper, a novel radar imaging method using nonperiodic interrupted sampling-LFM (NIS-LFM) signal is proposed. The radar anti-jamming performance can greatly benefit due to the random property of the NIS-LFM signal. Besides, the compressive sensing-based algorithm is further proposed for radar image reconstruction by utilizing the piecewise sparsity of the NIS-LFM echo. Both measured ISAR data simulations and microwave anechoic chamber experiments demonstrate the validity of the proposed imaging method.