Abstract-A novel dual-band filter based on substrate integrated waveguide (SIW) is presented in this paper. The proposed filter is composed of two filters with different center frequencies and bandwidths, where they share input and output ports with source-load coupling using rectangular SIW cavity structure. Multi-transmission zeros have been obtained through electrical coupling between the source and load, which improves the frequency-selective characteristics of the filter greatly. Finally, a Ku-band substrate integrated waveguide dual-band filter with bandwidths of 220 MHz and 120 MHz was finally designed, fabricated, and measured. The measurement results are found to be in good agreement with the simulation results.

An inline quarter-mode substrate integrated waveguide (QMSIW) filter with controllable finite transmission zeros (FTZs) is presented based on a novel frequency-dependent coupling structure, which is constructed by a microstrip line with a pair of symmetric metallized via/buried holes and a magnetic coupling iris between two resonant cavities. FTZ can be independently introduced and controlled on both sides of passband to achieve high selectivity while keeping the filter compact configuration unchanged. For demonstration, the proposed structure is analyzed in detail. An inline fourth-order QMSIW bandpass filter (BPF) with two upper FTZs is designed, fabricated, and measured. The synthesis results, EM results, and measured results are in accordance with each other, which confirms the effectiveness of the proposed method.

Utilizing the basic theory of heat transfer and computational fluid dynamics and considering the coupling influence of air in the channel and tunnel surrounding rock, the paper deduced control equation of hydrokinetics, calculated the formulas and made secondary development program applying UDF language on ANSYS FLUENT as a basis. Based on materials of Fenghuo Mountain tunnel, the paper analysis for coupled problem of heat transfer of surrounding rock and heat convection between air in cold region tunnel and surrounding rock, and comparative analysis of the annual average temperature between the calculation result and the actual observation records in 2004. The results demonstrated: in the laminar flow condition, the annual average temperature of the cross-section of tunnel entrance and exit is the same as or higher than the tunnel inside. In the turbulence fluid condition, the annual average temperature diminishes from entrance to exit, and there exists mutation between the cross-section of entrance and exit and other cross-section. When air flow state is assumed to be laminar inside Fenghuo Mountain tunnel, the calculation result and the actual observation records are the same. Assumed to be turbulent, both of result are different. Therefore, the calculation depend on the actual corresponding air flow state in tunnels in cold regions designs. The paper results will be providing the theory base and reference of design, construction and study of tunnels in cold regions.