Finite Element Analysis of Periodic Structures Without Constrained Meshes

A finite element analysis is detailed of periodic structures without constrained meshes. The infinite periodic analysis domain is reduced to the unit cell analysis by means of the Floquet-Bloch decomposition, where an admittance-type matrix approach is carried out. Special emphasis is placed on the admittance-type matrix generation in such a way that the constrained meshing problem is no longer required. As a result, periodic ports are permitted in the unit cell, and the Floquet-Bloch periodic conditions are easily applied in the admittance-type matrix by means of a connection-like handling. Several infinite periodic antennas are shown to be analyzed appropriately.