Higher order finite element analysis of finite-by-infinite arrays

This paper describes a finite element analysis of finite-by-infinite arrays with arbitrary composition. The analysis employs higher order tetrahedral elements for discretization and imposes appropriate boundary conditions on the unit cell boundaries. The radiation boundary condition imposed on the array aperture is derived through a spectral- and a mixed-domain formulation. The two formulations are found to produce consistent numerical results. In addition to a general code using tetrahedral elements, a special code is also developed based on brick element discretization, which utilizes the conjugate gradient fast Fourier transform (CG-FFT) method. Both computer codes are applied to the analysis of several finite-by-infinite arrays and numerical examples are presented to demonstrate their accuracy and capability.