Efficient generation of jamming signal is an important but intractable issue in active deception jamming against synthetic aperture radar. Considerations must be given to both the computational complexity and the focus depth of the false scatterers of a deception template. However, existing methods cannot meet both demands mentioned above when generating jamming signal of an extended false scene or scattered false targets. In this study, a frequency‐domain three‐stage algorithm (FDTSA) is proposed. In theory, the jammer system is deliberately reformatted in the two‐dimensional frequency domain. Accordingly, the implementation of the FDTSA can be effectively accelerated by fast Fourier transform and by separating the modulation process of a repeat jammer into three stages: the offline stage, the initialisation stage and the real‐time modulation stage. Theoretical analyses and simulation results indicate that the FDTSA can get rid of severe focus deterioration of the false scatterers and reasonable computational load is required.

The influence of intelligence gathering inaccuracy, especially the estimate error of radar kinematic parameter, on the performance of deceptive jamming against synthetic aperture radar (SAR) is studied in this paper, filling a knowledge vacancy in the field of SAR electronic countermeasures. For the first time, an equivalence relationship between non-ideal jamming and ground moving target is derived and verified in raw phase history data domain and radar image domain. A novel and elegant way to quantify the defocus and displacement of false target in radar image is proposed based on the equivalence relationship. Work presented in this paper can guide the design of jammer's intelligence gathering subsystem and optimize jamming configuration, from the view of jammer. The results also avail electronic counter-countermeasures, from the view of radar.

In this paper, a digital-domain reconstruction based radio-frequency (RF) interference cancellation scheme is proposed to cancel the nonlinear wideband self-interference (SI) signal in co-site radio systems. First, an auxiliary cancellation chain is employed to reconstruct and suppress the SI signal received at the receiver chain. Then, in order to generate the SI replica more accurately, we derive two nonlinear models to predicate the coupling characteristics for the nonlinear wideband SI signal. The proposed models combine the transmit chain and wireless SI channel characteristics, and employ both the Hammerstein model and Wiener model for the transmit chain, respectively. Next, the coefficients of each linear and nonlinear component in the SI chain are integrated into a coefficient vector, which is linear with respect to the output samples, with the proposed models. Based on the linearity, a dynamic least-squares (LS) type algorithm is developed to efficiently estimate and update the coefficients of the proposed models. Finally, experimental results obtained from a FPGA-based testbed have validated that the proposed scheme has a superior interference cancellation performance for nonlinear wideband SI.

Cross-eye jamming is a technique to counter monopulse radar. The impact of the amplitude-phase error on the jamming performance is one of the key problems for cross-eye jamming. The tolerance of amplitude-phase error for cross-eye jamming has been analyzed by deterministic analysis. However, the amplitude-phase errors of a practical jammer are commonly stochastic variables due to the variation of working conditions. In this paper, the probabilistic analysis of the amplitude-phase error tolerance for cross-eye jamming is studied. By demonstrating that the contours of cross-eye gain can be approximate to a set of ellipses, the probability distributions of cross-eye gain and angle factor are derived, based on the assumption that the amplitude-phase errors of cross-eye jammer are Gaussian distributed. The paper presents the instructions to determine the required standard deviation of the amplitude-phase error to produce a specific confidence level of cross-eye jamming performance metric.

The measurement and compensation of the amplitude-phase parameters (i.e., amplitude ratio and phase difference) are crucial to the performance of cross-eye jammers. An amplitude-phase measurement method for cross-eye jammers is presented in this paper, including a measurement circuit and a calculation method. The proposed measurement method realizes accurate and unambiguous amplitude-phase measurement for cross-eye jammers at low cost and low complexity. The proposed measurement circuit is designed by utilizing the reciprocity of RF passive components. The structure of the measurement circuit is simple. And the systematic errors are avoided. The proposed calculation method for the phase difference is based on comparing the theoretical errors of two candidate phase difference. The ambiguity of the phase difference in the range from -180° to 180° is overcome by combining two forms of signals synthesization. The errors of the proposed measurement method are clarified through theoretical derivations and verified through Monte Carlo simulations. The measurement experiments of a cross-eye jammer prototype indicate that the errors of the proposed measurement method are basically within ±0.3 dB and ±5° for the amplitude ratio and the phase difference, respectively, when in comparison to the measurement results obtained by a vector network analyzer (VNA).