Mutual Coupling of Open-Ended-Waveguides with Arbitrary Cross-Sections Located in an Infinite Groundplane

A Green´s function approach is used to analyse mutual coupling in a finite array of open-ended waveguides located in an infinite groundplane. For the cross-sections of the cylindrical waveguides there are nearly no restrictions. In the waveguides the field is expressed as a sum of the transverse electric (TE) and transverse magnetic (TM) waveguide modes, and expressions for the mutual admittances of modes excited at the aperture are obtained using a direct integration approach. From these expressions the mode reflection and conversion coefficients are determined. Computed and measured results are presented for the reflection coefficient of the fundamental mode in a single waveguide due to the open end as well as for the mutual coupling between two waveguides for E-and H-plane dispositions.