In this paper, we suggest a method of analyzing the post-wall waveguide (PWW) or the substrate integrated waveguide (SIW) by applying the analytical technique of the H-plane waveguide discontinuities based on the planar circuit approach. The analytical procedure consists of the derivation of the mode impedance matrices for regular-shaped circuits and the short-circuiting operation on fictitious ports arranged at the peripheries of the metallic posts. First, a straight section of the PWW is treated as an example and the analytical method for the calculation of the S-parameters is described in detail. Then the attenuation and phase constants of the PWW are computed with the aid of the Thru-Reflect Line (TRL) calibration technique. Next, the analytical method is applied to the design of two types of right-angled corners. The analysis and the design results are verified using an em-simulator (HFSS).