1. Introduction.- 2. Basic Structure and Characteristics of SIR.- 3. Quarter-Wavelength-Type SIR.- 4. Half-Wavelength-Type SIR.- 5. One-Wavelength-Type SIR.- 6. Expanded Concept and Technological Trends in SIR.- Appendix. Analysis of Resonator Properties Using General-Purpose Microwave Simulator.- A.1 Design Parameters of Direct-Coupled Resonator BPF.- A.2 Filter Design by Experimental Method.- A.3.2 Determination of Coupling Coefficient.- References.