Admittance characteristics of slots in non radiating dielectric waveguide using the modal expansion method

The authors describe a way of calculating the admittance characteristics of a slot in a nonradiating dielectric (NRD) waveguide based on the modal expansion method using the reciprocity theorem and the Poynting theorem. The different regions to be considered for the application of the reciprocity theorem and calculation of the Poynting vector are shown. The application of reciprocity to the total fields with appropriate test field sets over the volume around the slot enables the expansion coefficients to be determined in terms of the incident and induced slot fields.<>