Equivalence between waveguides with side walls of cylinders (SIRW) and of regular solid sheets

Rectangular waveguide with sidewalls of vertical conducting cylinders (i.e., substrate-integrated rectangular waveguide - SIRW) becomes popular with the advent of LTCC structure; its analysis, however, is usually done numerically or modally (Cassivi et al., 2002), leading to empirical design formulas. This paper, however, identifies its equivalence to the well-known regular waveguide of solid walls. This identification indicates that the solution of SIRW waveguide may be as just as simple and analytical as that of a regular waveguide. Formula of the radiation leakage from SIRW is also found in the process.