Design and Fabrication of a Frequency-Agile and Surface Mountable Suspended Integrated Strip-Line (SISL) Bandpass Filter

Abstract

Modern radar and communications systems have increasingly high demands for low cost, size, weight, and power (C-SWaP) that will prove a challenge to satisfy. Surface mount technology is an excellent way to place components densely at low cost, but lumped element components perform poorly at high frequencies. Distributed components perform better at higher frequencies, and planar components are both cheap and relatively small. However, planar components cannot simply be surface mounted because they require specific electromagnetic field distributions to operate correctly. The challenge is therefore developing packaging that is surface mountable and does not disturb the component's field distributions, allowing integration into a larger system. This thesis aims to increase integration of microwave systems by designing and fabricating a novel surface mount technique using castellated vias and suspended integrated strip-line (SISL) technology. The proposed technique uses SISL as a low-loss and highly integrated packaging that preserves the electromagnetic field distribution of planar components while castellated vias allow the package to be surface mounted easily. A DC-4 GHz thru-line is presented, demonstrating the low loss of the technique. It is then applied to a varactor-based filter tunable from 2.4 to 3.9 GHz, demonstrating further possibilities to reduce C-SWaP.