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.
In this paper, a multilayer graphene mixer with inductor-capacitor resonators (LCR) and microstrip reflector stubs (MRS) loaded with direct-current (DC) voltage bias is presented. As a multifunctional material, multilayer graphene is especially suitable for mixer because of its nonlinearity. The experimental and simulation results show that the effect of bias voltage on multilayer graphene is significant. When the bias voltage is applied, the mixer is converted from subharmonic mixer to fundamental wave mixer. The measured minimum conversion loss with DC-load fundamental wave mixer is 18.9 dB at P LO = 16 dBm, f LO = 800 MHz, p RF = 0 dBm, f RF = 2 GHz which is about 1.2 dB lower than that DC-free subharmonic mixer. In addition, the nonlinear model of graphene is established by simplifying the approximate conductivity.
A W-band low sidelobe level offset-fed reflectarray antenna is designed, fabricated, and measured. Compared to conventional offset-fed reflectarray antenna, the sidelobe level of proposed one is decreased significantly when the inclination angle of reflector is half of the incident angle of the feeding. At the same time, a large-radiation-area element is used to obtain low sidelobe level for the offset-fed reflectarray antenna because of its large radiating element area and low specular reflection. A 52 mm×180 mm offset-fed reflector antenna have been designed and measured to verify the availability. From 90 to 96 GHz, measured results show that a maximum gain of 36dBi at 93 GHz, and the peak sidelobe level of 18dBc can be obtained with the proposed architecture.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.