TLM modeling of a probe-coupled cylindrical cavity based on compact wire model in the cylindrical mesh

Abstract

This article describes an implementation of a compact wire model into the three-dimensional transmission-line matrix (TLM) cylindrical mesh for the purpose of an efficient analysis of probe-coupled cylindrical microwave cavity devices. Because of a cylindrical grid structure and empirical nature of the compact model, this implementation has to take into account a change of wire model parameters with a variable cross section of the TLM nodes through which a wire conductor passes. The model accuracy has been experimentally verified and compared with the corresponding results reached by the TLM method based on a rectangular grid in order to consider its advantages.

Efficient integral cylindrical transmission‐line matrix modelling of a coaxially loaded probe‐coupled cavity

“…Finally, the TLM solver based on the cylindrical grid has been recently enhanced by implementation of the compact wire model [18], represented by the wire network that models signal propagation along the wire allowing for interaction with an EM field. It consists of new elements in a form of link and stub lines to account for an increase of an inductance and capacitance caused by the wire presence [15].…”

“…Therefore an additional connecting procedure for wire segments running along a radial direction has been developed and implemented into the existing TLM-based software in the cylindrical grid [18].…”

“…However, a maximum time step in the non-uniform mesh made of SCN with stubs could be small resulting in a greater simulation time. Because of that, the presented TLM solver in the cylindrical grid [18] is based on the hybrid SCN (HSCN) of type I, which is generated by adding only capacitive stubs and uses three different characteristic impedances of link lines [20]. This node enables operation at a higher time step which leads to a better efficiency.…”

“…For that purpose, an additional algorithm handling the connecting procedure for wire segments belonging to the TLM nodes with different cross-sections has been developed. This solver has been already verified on an empty probe-coupled cavity for different probe radii and lengths [18] and on a probe-coupled cavity with plan parallel placed dielectric samples [19].…”

“…However, when this model incorporated into the rectangular grid-based TLM method is applied to a probe-fed cylindrical cavity resonator, where the probe is placed along the radial direction, there are two opposite requirements to satisfy: one is related to applying the mesh of higher resolution because of the precise modelling of boundaries and the other is related to the implementation of the compact wire model requiring the probe radius that is significantly smaller than the cross-sectional size of TLM nodes through which the wire propagates [15]. As a consequence, the maximum probe radius that provides convergence of the results is limited [18]. A problem of choosing an adequate rectangular TLM meshes and herewith the probe radius limitation becomes more pronounced when a coaxial load is placed into the cavity requiring finer mesh to be applied.…”