This paper demonstrates the feasibility of detection and localization of multiple stationary human targets based on cross-correlation of the dual-station stepped-frequency continuous-wave (SFCW) radars. Firstly, a cross-correlation operation is performed on the preprocessed pulse signals of two SFCW radars at different locations to obtain the correlation coefficient matrix. Then, the constant false alarm rate (CFAR) detection is applied to extract the ranges between each target and the two radars, respectively, from the correlation matrix. Finally, the locations of human targets is calculated with the triangulation localization algorithm. This cross-correlation operation mainly brings about two advantages. On the one hand, the cross-correlation explores the correlation feature of target respiratory signals, which can effectively detect all targets with different signal intensities, avoiding the missed detection of weak targets. On the other hand, the pairing of two ranges between each target and two radars is implemented simultaneously with the cross-correlation. Experimental results verify the effectiveness of this algorithm.
Low conversion loss (CL) and high isolation graphene harmonic mixer with inductor-capacitor resonators and microstrip reflective stubs (MRS) is presented in this paper. The nonlinear electromagnetic field characteristics of the multilayer graphene are similar to those of an antiparallel diode pair, which has very strong nonlinear characteristic and is suitable for the development of the Low-level even-combinatorial-frequency harmonic mixer. Through the reflection of radio frequency (RF) signal and local oscillator (LO) frequency signal, the CL of graphene harmonic mixer is significantly reduced, and the isolation between the ports is also improved. The measured minimum CL at the LO power of 16dBm is about 19.2dB, and 2-3dB lower than that without MRS over the frequency band from 2.05-2.5GHz, while the isolation between ports is better than 30dB.
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