A radio frequency memory (RFM) based on microwave photonic mixing and digital RFM is proposed and demonstrated. By introducing the microwave photonic mixing, the operational frequency range is largely extended. Besides, the mixing spurs are effectively suppressed, which is important to guarantee the system efficiency and avoid generating significant feature for the jamming recognition. Meanwhile, by applying the digital RFM, flexible modulation and reconstruction are achieved. A proof-of-concept experiment is carried out. The wide working frequency range from C- to Ka- bands is achieved. The mixing spurs over the 0–40 GHz frequency range are experimentally suppressed. Radar imaging is successfully deceived. A radar waveform with a bandwidth of 500 MHz in the K band is successfully received and reconstructed. Two false targets are added. To the best of our knowledge, it is the first time that a photonics-assisted RFM is reported to have the functions of storage, flexible modulation, and reconstruction with wideband RF signals at a high frequency. The proposed scheme shows the great potential to be applied in electronic warfare, electronic environment simulation and testing, and so on.

The range and azimuth information of a target can be obtained after coherent pulse accumulation of the traditional multiframe stepped‐frequency (SF) synthesis wideband echo and spectrum analysis, and high‐resolution two‐dimensional imaging of the target can be achieved. However, the accumulation of a certain number of pulses requires a long beam dwell time, which cannot meet real‐time imaging requirements for high‐speed radar moving platforms. To solve the above problems, a scanning imaging mode is proposed by combining forward‐looking imaging and scanning imaging, and a target echo signal model with the structure of scanning stepped‐frequency is constructed. The SF pulses are grouped and transmitted according to the scanning order, and the echo pulses are sorted and reorganised. After the timing compensation and range Doppler coupling compensation are completed, the target is located and projected. The proposed imaging mode can achieve high‐resolution scanning forward‐looking imaging and can basically attain an azimuth resolution of approximately 0.1° within the forward‐looking scanning range. This imaging mode has higher real‐time performance and a larger target imaging range than the traditional methods. Moreover, the simulation results showed good performance via the scanning imaging method.

In order to solve the problem that the array beampattern varies greatly with the angle during spatial scanning, this paper presents a synthesis method of the conformal array beampattern based on “spatial-variability (SV)” suppression. In order to obtain a stable beampattern, the convex optimization method is used to solve the weighted value of the amplitude and phase of the elements under the condition of satisfying the set beam gain threshold so that the optimized main lobes of the beams with different directions approach the main lobe of the reference beam. Since beams of different dimensions have different broadening degrees after optimization, we weighted the objective function and solved the optimal weights by the golden section search method (GSM) to improve the comprehensive optimization results of two-dimensional beams. The simulation results demonstrate the effectiveness of the proposed method.

This paper made statistics on the proportion of electrical fires in total fire disasters in China, analyzed the causes of electrical fires as well as the current protective measures and their advantages and disadvantages, and introduced the composition, working principle, verification results of main technical parametersand application prospects of the new environmental-friendly temperature-fixing circuit fuse with the fire extinguishing function.

Aiming at the problem that the azimuth echoes of forward‐looking scanning imaging are aliased and the angular information of different targets cannot be directly separated, resulting in low azimuth resolution, the authors propose a scanning imaging method based on azimuth modulation and pulse compression in this paper. Firstly, the coupling of slow‐time and scanning angle is utilised to transmit time‐varying azimuth‐modulated pulses while the beam is scanning, and phase demodulation is performed during the echo processing; then the azimuth pulse compression is used to accumulate effective power and obtain the azimuth information of different targets. The proposed method not only obtains high azimuth resolution of the forward‐looking area, but also has a simple processing process and good anti‐noise performance. Simulation and analysis demonstrate the effectiveness of the proposed method.