A Correction to Head-Wave Fields for a Simple Planar Contrast of Permittivity

When asymptotically describing the wave fields on the denser side of a planar permittivity interface, the canonical head-wave fields of the tangential-magnetic (TM) set show discrepancies with the full-wave fields. This paper derives the correction fields that supplement the canonical TM head-wave fields, by taking into account the proximity between the head-wave branch point and an extraneous pole in the wavenumber domain. The validity of the correction is demonstrated in the time domain by comparing the waveforms of a corrected field and the full-wave field, for various ratios of permittivity and at various locations of observation. Consideration is also given to the case of a conducting medium.