SMT enabled microwave package with waveguide interface

摘要

A microwave package for surface mount technology (SMT) integrates in its multilayer structure a waveguide interface comprising a microstrip to rectangular waveguide transition. The transition includes a patch at the end of a launching microstrip faced to a slot which is dug into a copper plate 0.5 mm thick, constituting the ground plane for the topmost microstrip layout and thermal sink for MMICs supported on it. The slot acts as an iris allowing propagation of fundamental TE 10 mode into a waveguide interface including a parallelepipedal cavity dug into the thickness of copper laminate under and around it starting from the bottom of the multilayer. The metallized cavity extends until the ground plane at the bottom with a cross-section preferably equally dimensioned as the external waveguide. The metallization of the cavity walls joins the ground plane at the bottom without breaking the continuity. Metallization of ground plane continues along the very narrow side walls determined by the thickness of multilayer. A metal lid is soldered along a metallized perimetrical frame on the upper layer. The lid is internally carved to obtain a cavity faced to the transition for reflecting back to the slot the power irradiated upwards. The ground plane on the bottom face includes the mouth of the internal waveguide tract, and the contacting beams for an external layout of the supporting PCB. The package is ready to be soldered to a PCB including in its turn a very short waveguide tract in its thickness between the mouth of the package and a metallic waveguide dug into the supporting mechanics (fig.10)