The Random Feeding Phases (RFP) method is proposed and validated for diagnosing faulty elements in phased arrays. The core principle involves applying random phases, obeying a uniform distribution, to each array element through phase shifters, thus inducing the statistical behavior of radiated field. For a normal and fault-free phased array with RFPs, statistical radiation patterns of the complex electric field (both the real and imaginary parts) at a fixed field point vary within a specific region, whose analytical deductions are performed and verified. When an element malfunctions, the corresponding source in the composite field disappears, disrupting the initial coherent superposition and altering the statistical boundaries of the radiation pattern. The sequential behavior associated with successive failures of individual elements is detected at particular sampling points, and the optimal sampling range is further precisely determined. By mapping the faulty cases to statistical patterns, fault diagnosis can be achieved through the measured distribution area of the statistical radiation pattern at a fixed location. Explicit physical interpretability is reflected. The number of sampling points as well as the testing costs are greatly reduced. Both simulated and experimental results demonstrate the efficacy of this method for phased arrays with one or two defective elements.

Based on the characteristics of electromagnetic compatibility related courses, aiming at the problem of lacking a complete and concrete experimental teaching system that can demonstrate the electromagnetic coupling paths in the course of electromagnetic compatibility teaching, Starting from the basic theory of electromagnetic compatibility and referring to the coupling and radiation theories of microstrip lines, a visual experimental teaching system of electromagnetic coupling paths is designed and made, achieving the visualization of field-field, field-circuit, circuit-field and circuit-circuit electromagnetic coupling paths. The experimental teaching system has a simple structure and does not require external interference sources. It can use simple experimental instruments to realize the visual display of four coupling paths at one time, and the coupling effects are obvious and intuitive. The experimental teaching system is helpful to deepen students’ understanding of the coupling channels in the “three elements” of electromagnetic compatibility, and lays a foundation for the subsequent teaching of related courses.

Recently, Software-Defined Radio (SDR) has gained great popularity owing to its attractive merits, such as flexible signals configuration in multiple channels. However, commercial SDR equipment also has large spurious emissions in the Transmitting (Tx) channel. This paper presents a cascaded model for the Conducted Emission (CE) properties of a general SDR platform, which captures all the key components with high precision. Based on a deeper understanding of the CE properties, a mitigation method is proposed for suppressing the spurious emissions of an SDR Tx channel. This method is based on an efficient vector signal cancellation scheme, in which multiple SDR channels are adopted to suppress the second- and third-order harmonic signals simultaneously. A hardware prototype with dual SDR channels is built and measured for verification. Experimental results show that the suppression level of the third-order harmonic signal is 24 dB on average in the frequency range of 100 MHz to 3000 MHz. The theoretic limit of the suppression level is related to the magnitude and phase errors, and the suppression level may be further improved by calibrating each SDR channel.