Transmission line to waveguide transition structures

摘要

A planar structure is provided for coupling electromagnetic signals between a planar transmission line and a waveguide (10). The planar structure comprises a shielded patch antenna (24) and one or more capacitive diaphragms (28) disposed adjacent to the patch antenna (24). This structure is advantageous to MMIC (monolithic microwave integrated circuit) modules in connecting from a planar transmission line of a substrate carrying an MMIC to an external waveguide without the need of a non-planar back metal short, which is normally essential to avoid back scattering from waveguide and also normally needed to achieve impedance matching. The disclosed patch antenna (24) radiates into the waveguide (10) while the antenna's ground plane reduces back scattering from the waveguide (10). The one or more capacitive diaphragms (28) provide impedance matching between the microstrip and the waveguide (10).