Influence of lattice geometry on transmission of electromagnetic waves through arrays of crossed dipoles

Copolar plane-wave transmission and reflection coefficients have been computed in the principal planes for arrays of crossed dipoles, arranged on ten different lattices. A modal method was used in the calculations. Results are presented for dipoles 4.2 mm in length on a dielectric substrate 0.075 mm thick in the frequency range 1 to 60 GHz. Computed and measured coefficients are compared for a sample lattice, and the number of current and Floquet modes needed for the covergence of the two sets of results are discussed. At frequencies near resonance of the asymmetrical current component the choice of modes is more critical. The results provide a guide to the operating bands attainable with feeds at the Cassegrain and prime focus positions, in a 0.33 F/D reflector antenna system.