Slot-coupled double-sided microstrip interconnects and couplers

A broadband slot-coupled microstrip vertical interconnect and a microstrip double-layer quadrature coupler are presented. The interconnect uses virtually terminated microstrip-to-sandwich slotline transitions and demonstrates broad bandwidth, low loss, and high efficiency coupling. The interconnect showed less than 1 dB insertion loss over a bandwidth of more than 2.6 octaves which covered the L, C, and S bands. The microstrip double-layer quadrature coupler, consisting of two parallel microstrip lines coupled by two virtually terminated narrow slots, showed an isolation of greater than 15 dB and a phase quadrature of 90 degrees +or-2.5 degrees over a bandwidth of 14%. Due to the advantages of compact size, light weight, high density, and good isolation, these 3D noncontacting RF couplers are very suitable for multilayer and large-scale MIC (microwave integrated circuit) and MMIC (monolithic microwave integrated circuit) applications.<>