Efficient Equivalent Circuits Model for Electric-LC Resonators in Periodic and Closed Waveguides

This paper details the extraction of possible equivalent circuits over a wide band for an Electric-LC resonator in two technological configurations: a) a multilayer stack working at mm-wave and b) a WR90 waveguide in the X band. The proposed equivalent circuits are based on a T structure or on only one shunt susceptance with two transmission lines. An identification process applied to the frequency behavior of the reactance/susceptance is used to obtain a more appropriate and efficient equivalent circuit, giving a physical meaning, if any, to each inductance, capacitance or resonator tank contained in the proposed circuits. Finally, experimental results are obtained for the ELC in the WR90 waveguide and used to identify an equivalent circuit able to represent also the effect of the material losses.