CAD APPLYING THE FINITE-ELEMENT METHOD FOR DIELECTRIC-RESONATOR FILTERS

The progress of numerical techniques now permit us to analyze rigorous ly complex devices such as dual-mode cavity multipole filters or plana r passive elements for coplanar monolithic microwave integrated circui ts (MMIC's), In this paper, we describe a rigorous design of dielectri c resonator (DR) filters applying the finite-element method (FEM), We first present a dual mode coupling technique which replaces classical DR's, coupling, and tuning screws, which are commonly used in dual-mod e filters, by slotted DR's. Next, a new theoretical analysis based on the contribution to the dual-mode filter response of the first DR hybr id mode and of higher order modes is described, This analysis can be a pplied to any type of microwave dual-mode filter, It allows us to defi ne a procedure which explains the presence and controls the position o f the two transmission zeros in the filter responses, In this paper, t his procedure has been applied to improve filtering performances of a dual-mode DR filter, Finally, a synthesis method is developed to rigor ously design for the first time, a four-and an eight-pole slotted DR e lliptic filters, The experimental results were obtained with no tuning and the theoretical ones show good agreement.