A method of calculating admittance of waveguide slot

A method of extracting waveguide slot admittance based on the simulated results of the commercial software HFSS is presented. The formula of calculating self-admittance of a single slot in waveguide is derived from transmission line theory, and that of calculating active admittance of a slot in array is given, simultaneously. With the proposed method, a waveguide slot antenna array can be designed easily and economically.