Effective ionospheric height for a simplified mode conversion model at VLF
Abstract
This report generalizes an earlier program for calculating the effects on signal level of mode conversion at VLF/LF frequencies in the earthionosphere waveguide. The generalizations are (1) horizontal inhomogeneities are allowed to pass over the transmitter; and (2) the height parameter above which the height gains are discarded and below which the height gains are replaced by a linear combination of Airy functions is allowed to vary from slab to slab. Several methods of selecting the height parameters are examined. Although no one method appears to be superior, the reference height defined by Wait in his studies of exponential profiles, because of ease of implementation, is the preferred method. The present program will yield generalized mode conversion coefficients and a mode sum plot for ground based vertical electric dipole excitation of the vertical electric field at the ground as a function of transmitterreceiver distance or as a function of location of the horizontal inhomogeneity relative to the transmitter for fixed point transmissions.
 Publication:

Interim Report Naval Electronics Lab. Center
 Pub Date:
 November 1975
 Bibcode:
 1975navy.reptR....P
 Keywords:

 Ionospheric Propagation;
 Very Low Frequencies;
 Airy Function;
 Computer Programs;
 Conversion;
 Electric Fields;
 Mathematical Models;
 Propagation Modes;
 Waveguides;
 Communications and Radar