Coupling and radiation through "V-shaped" narrow slots using the FDTD method

A "V-shaped" slot in the narrow wall of a rectangular waveguide is presented as a coupling element. Three- and four-port coupler parameters and the radiation characteristics of the slot were investigated using the finite-difference time-domain (FDTD) method. Two approximate numerical-analytical procedures are proposed to reduce the computer requirements and predict multislot device characteristics. A clear improvement in four-port coupler parameters was observed following the incorporation of a thin dielectric layer.