Design of passive microwave components on multilayered printed circuit boards using functional vias

This thesis deals with the design of passive components such as microwave filters, couplers, and networks on multilayered substrates using functional vias. Vias (plated through holes) are essential elements in modern multilayer printed circuit boards (PCBs). They provide electrical and thermal connection between different layers of conductors. With a steadily increasing demand on high bandwidth data transmission, the operating frequencies achieve multiple tens of GHz where the physical effect associated with vias become parasitic. In this work these parasitic effects are carefully analyzed and exploited in order to use vias as functional elements. First, the via stub effect is utilized in single and double stub matching networks. Secondly, via stubs are used as quasi-transmission lines as low-pass, band-pass and band-stop filters. Finally, the mostly unwanted parallel plate modes are used for building a directional coupler. The designs of filters and couplers are compared to common planar microstrip implementations with regard to overall size, manufacturing issues and electrical performance. All microwave designs were evaluated using theoretical predictions, quasi-analytical and full-wave simulations. The calculated results are supported by measurements of scattering parameters up to 35 GHz in most cases. Several test boards have been designed, fabricated, and measured for this purpose. The application of vias as functional elements as proposed in this work shows several advantages such as high isolation against external signals due to an appropriate shielding, smaller footprint compared to planar implementation, and its potential for 3D-integration of microwave components.