Novel substrate integrated waveguides and components

This thesis examines the properties of novel waveguides at mm-wave frequencies as advanced alternatives to the conventional components used today in research as well as in commercial applications. The analysis begins with the folded waveguide, a space saving substitute for the well known Rectangular Waveguide (RWG). Folded waveguides are dielectric-filled metallic structures that preserve the original modes of a rectangular waveguide in a more compact geometry. There are two types of folded waveguides, type 1 and type 2 both of which are narrower than RWGs. Furthermore it is proved that the bandwidth characteristics of type 1 are by far superior to those of an RWG. Due to the closed nature of folded structures the dispersion characteristics are identical to those of RWG. This thesis presents design equations for type 1 and type 2 guides and discusses their fabrication process as well as their ability to form multilayer stacks with even greater benefits in bandwidth and reduced dimensions. By introducing discontinuities in the transmission line of a folded guide we create resonating cavities with controllable response i.e. a filter. Hence it is shown that folded guides form the basis for a new class of folded-based components with the benefit of small widths. Another novel type of waveguide analysed in this thesis is the Non Radiative Perforated Dielectric Waveguide (NRPD). The structure is based on the operating principle of the conventional Nonradiative Dielectric Waveguide (NRD) but, instead of air, the slab is surrounded by perforated dielectric. Our structure uses the same theory as the NRD with the only difference being the value of the surrounding permittivity which is equal to the equivalent permittivity of the perforated lattice. NRPD shows manufacturing superiority over conventional NRDs and allows the fabrication of NRPD components such as filters, based on the resonating cavity principle.