Numerical modeling of impedance loaded multi-arm Archimedean spiral antennas

A method of moments formulation for the current on arbitrarily shaped thin wires is applied to the problem of radiation and scattering from Archimedean spiral antennas. This formulation includes impedance loading along the wires. Additional analysis is performed to take advantage of structures which exhibit discrete rotational symmetry. Numerical results for a four-arm Archimedean spiral antenna with and without impedance loading are compared, showing that the loading significantly affects the current distribution and the far-field pattern for the higher order modes