Compact top-wall hybrid/coupler design for extreme broad bandwidth applications

A design approach for compact waveguide top-wall short-slot 3 dB hybrids is introduced to achieve high performance properties over extreme large bandwidths up to 30%. The hybrid principle relies on the dual mode propagation of TE10/TEM modes in a common coupling region. The CAD, established for this design task, is based on a combined Finite Element / Mode-Matching (FE/MM) method to accommodate with the particular constraints of the structure. Several hybrids have been designed for frequency bands from 4 to 40GHz. Validation of this novel CAD approach is demonstrated by a realized 12GHz design which exhibits accurate coincidence of computed and measured characteristics.