On the evaluation of Sommerfeld integrals

Some of the basic recent developments in the evaluation of Sommerfeld integrals are reviewed. The image approximation of the integrals is extended to include both the earth permeability and the effect of the displacement currents. The non-uniqueness of the field representation in terms of Hertz vectors is stressed and a proper representation for horizontal dipoles is used. The semi-analytical evaluation of the integrals using the fast fourier transform (FFT) is extended via proper decomposition of the integrand. The analysis increases the range of applicability of these techniques.