Impedance properties of slots in NRD waveguide using the variational method

A method of analysis for calculating the impedance of slots cut on the metal wall of a non radiative dielectric (NRD) waveguide is presented. With the aid of Parseval's theorem, an expression for the admittance, presented by the radiating slot to the feed NRD waveguide, is determined from the angular spectrum of plane waves and the discontinuity in modal current. In this analysis only the dominant LSM01 mode is assumed to be propagating. Numerical values agreed with previously reported experimental results.