Single-beam leaky-wave antenna with wide scanning angle and high scanning rate based on spoof surface plasmon polariton

We propose a single-beam leaky-wave antenna(LWA) with a wide-scanning angle and a high-scanning rate based on spoof surface plasmon polariton(SSPP) in this paper. The SSPP transmission line(TL) is etched with periodically arranged circular patches, which converts the slow-wave mode into the fast-wave region for radiation. The proposed LWA is designed, fabricated, and tested. The simulated results imply that the proposed LWA not only achieves a high radiation efficiency of about 81.4%, and a high scanning rate of 12.12, but also has a large scanning angle of 176° over a narrow operation bandwidth of 8.3-9.6 GHz(for |S_(11)| <-10 dB). In addition, the simulated average gain of the LWA can reach as high as 10.9 d Bi. The measured scanning angle range is 175° in the operation band of 8.2-9.6 GHz, and the measured average gain is 10.6 dBi. The experimental results are consistent with the simulation, validating its performance. An antenna with high radiation efficiency, wide scanning angle range, and high scanning rate has great potential for application in radar and wireless communication systems.

Slow Phase Transition-Induced Scan Rate Dependence of Spin Crossover in a Two-Dimensional Supramolecular Fe(III)Complex

Spin crossover(SCO)is commonly accompanied by a synchronous phase transition.A few phase transitioncoupled SCO compounds have been reported,yet the synergy between SCO and phase transition on different time scales has not been explored.Herein,we report an[Fe(H-5-Cl-thsa-Et)(5-Cl-thsa-Et)]·H2O(1·H2O;H2-5-Cl-thsa-Et=5-chloro-salicylaldehyde ethylthiosemicarbazone)Fe(III)complex that displays a two-dimensional supramolecular structure and SCO behavior above room temperature.Its dehydrated form1 exhibits a two-step spin transition with aplateau in the temperature-dependent magnetization(M−T)curve at room temperature and a 51 K thermal hysteresis loop(Tc↑↓=299/248 K)at a rate of 5 K/min.The improved SCOperformance in 1 could be attributed to the stronger intralayer but weaker interlayer interactions,which is supported by single-crystal structural analysis and density functional theory calculations.Remarkably,complex 1 displays an unusual scan rate-dependent SCO behavior at rates of 0.5−30 K/min,in whichM−T curveplateaus appear at lower scan rates(<10 K/min)but vanish at faster scan rates(≥10 K/min).Scan rate-dependent differential scanning calorimetry,powder X-ray diffractometry,timedependent magnetic moment decays,and infrared spectroscopy consistently reveal that the slow structural relaxation is coupled with a slowcrystallographic phase transition,which is the mechanism for the unusual scan rate-dependent SCO.