HIGH PERFORMANCE 1.8-18GHZ 10-DB LOW TEMPERATURE CO-FIRED CERAMIC DIRECTIONAL COUPLER

This paper presents a six-section multi-layer asymmetric 10dB directional coupler based on ofiset broadside coupled striplines, using Low Temperature Co-flred Ceramic (LTCC) technology, which operates over a decade bandwidth from 1.8 to 18GHz. It features high performance transitions between the external signal layer and the buried signal layers, as well as a novel mixed flrst section to solve the limitations of the coupler access bends. A prototype was manufactured that exhibits a return loss of better than 15dB, isolation of better than 23dB and a high coupling accuracy of 10:3§0:6dB over the 1.8{18GHz band. This design outperforms previously reported results in terms of bandwidth and shows excellent potential for microwave measurement applications.