Comparison of electromagnetic propagation predictions from IREPS and RPO across a coastal transition

Abstract

The Navy's existing electromagnetic propagation prediction software, the Integrated Refractive Effects Prediction System (IREPS), neglects signal leakage from a duct, approximates diffraction, and assumes atmospheric horizontal homogeneity. To ameliorate these deficiencies, the Radio Physics Optics (RPO) program is being developed. This thesis analyzes the significantly different propagation predictions of the two models. RPO predicts significantly shorter propagation ranges in a duct than does IREPS. RPO predicts variations in duct thickness and height which IREPS idealizes, and RPO also computes a signal strength above the duct. Only RPO predicts significant interactions between the duct's dM/dz gradient and frequency. RPO is capable of modeling propagation paths for an inhomogeneous atmosphere. Neglecting atmospheric inhomogeneities in a coastal region introduces significant propagation prediction errors.