Mixed path ground wave propagation: 1. Short distances

Abstract

An expression is derived for the mutual impedance between two short vertical antennas on a flat earth with a straight boundary separating two media of differing electrical constants. After making some approximations that are valid at low and medium frequencies and where the antennas are not near the boundary, the integral formula for the field is evaluated for a wide range of the parameters. The numerical results computed in this paper are shown to be in reasonably good agreement with experiment. Finally, the effect of the obliqueness of the boundary is considered by a refinement of the stationary phase evaluation of the integrals.