Vector-FEM Analysis of Millimeter Wave Circulator with SOC Truncation Technique

In this paper, the application of the edge-based vector finite element method combined with the short-open calibration (SOC) technique to waveguide junction circulators was presented. By applying permittivity and permeability tensors, the functional formula for tetrahedral vector elements are analytically derived in terms of the electric field strength. And the SOC technique is directly accommodated in the FEM algorithm and used to truncate the computational domain. The SOC technique removes or separates unwanted parasitics brought by the approximation of the impressed voltage source and also the problem of resulting inconsistency between different simulations. Truncation of computational domain by SOC technique makes the iterative solvers for large-sparse linear matrix equations from FEM converge much faster than by perfectly matching layers (PML). The analysis of three 2-port networks is sufficient to form the admittance matrix of the corresponding three-port waveguide junction circulators. To validate the theory, typical three-dimensional numerical results of isotropic dielectric-filled discontinuity are first presented and compared with other hybrid numerical techniques. Further, the ferrite filled waveguide junction circulators are analysed and compared with the measured and available publications. The comparison shows that good agreement is obtained.