**Abstract**

With the development of microwave wireless communication technology, microwave passive frequency selectivity circuits are developing toward multi-function and miniaturization. Substrate-integrated waveguide (SIW) devices have good development prospects in miniaturization and integration. The research on devices based on SIW is lack unified theoretical combing. This chapter describes the novel circuits based on substrate-integrated waveguide, including filter, power divider, switch, phase shifter, diplexer, and crossover. This chapter describes the design methods and special properties of these circuits. The display of these circuits is expected to give some inspiration to your research.

**Keywords:** substrate-integrated waveguide, filter, power divider, switch, phase shifter, diplexer, crossover
