Study on dispersion characteristics of terahertz waves in helical waveguides

Abstract

Corresponding to the atmospheric transmission windows of the electromagnetic spectrum in the low terahertz range, the mode coupling and dispersion characteristics of two helically corrugated waveguides (HCW) in the frequency ranges of 90 GHz–100 GHz and 260 GHz–265 GHz are studied. Through analytic calculations and numerical simulations, dispersion curves and structural parameters of the two frequency ranges waveguides are obtained. A novel method was proposed to obtain the dispersion of the HCW from the eigenwave solution using a periodic boundary condition. The HCW in a frequency range of 90 GHz–100 GHz was fabricated and its dispersion performance was measured. By comparing the measured results with the theoretical and the simulated results, the validity of the analytical and simulation method is verified. Limited to our machining capability, the dispersion of the 260 GHz–265 GHz HCW was only simulated and calculated and it was found that the results agree well with each other.

River Flood Characteristics Along the Canal Area Effected By Hanzhuang Canal Jacking

“…Among them, the upstream of the river in the mixed hillplain area is mostly hilly land with steep slope, short source and rapid flow, and the middle and lower reaches enter the plain or depression area with slow slope, which is susceptible to the dual influence of the inflow from the upstream basin and the top support of the downstream water level, and the risk level of flood disaster is high. Lots of scholars have carried out a large number of studies on flood disasters, but most of the studies mainly focus on flood disasters caused by incoming water in the upstream basin [2][3][4][5][6][7], and there are relatively few studies on flood disasters affected by downstream water jacking. Hu Guojian et al [8] used a two-dimensional numerical model to analyze the influence of the lower reaches of Puyang River on the crest of Qiantang River.…”