Double-layer Substrate Integrated Waveguide (siw) Transmission Theory And Engineering Applications

This paper is mainly focused on the theoretical analysis and engineering applicationof double-layer SIW structures. Based on our formula of width equivalence of SIWand RW, the formula of length equivalence of SIW and RW has been derived, whichis expected to find wide applications in the engineering design of SIW filter andresonance cavity.Benefiting from the LTCC and multi-layer PCB technologies, multi-layer SIWdevices can be constructed. In this way, a novel coupling structure is proposed, thepropagation characteristics between double-layer SIW must be investigated. Based onthe SIW cavity theory, the formulas to calculate the upper and lower frequencies ofthe pass band of the double-layer SIW structures are obtained.The waveguide-type directional coupler is one of the most important microwavedevices, and can be used in many microwave systems. The waveguide-typedirectional coupler takes the advantage of high Q value, large power capability etc,however, its 3D structure hobbles its application in MMIC. In this work, the SIWdirectional couplers with two kinds of coupling structures are proposed andtheoretically investigated. The formulas to calculate the coupling factor and isolationof the directional coupler are derived. The agreement between the simulation andcalculations are quite good, demonstrating the validity of our formulas.