WEPH V Code Modifications for HF Propagation and System Performance Modeling.

The report describes modifications to the WEPH V code that permit the use of the code for evaluation of HF propagation and system performance in nuclear-disturbed environments. The propagation and system models are an extension of those presented in the DNA HF Communication Handbook DASA 1955-1 and-2. The principal degradation effect modeled is D-region absorption. While changes in sky-wave geometry due to the disturbed environment are not determined, modifications to F-region critical frequencies at selected points are evaluated from approximate models. The modified WEPH V code is intended for use in rapid evaluation of the effects of propagation, system, and environment parameters on system performance, and to identify situations where analysis with detailed ray tracing codes such as the NUCOM code DASA 2035 is required. Author