Analyzing the HF field in the wave zone of the antenna using the normal-mode approach

Abstract

An analysis is made of the overall representation of the HF field as a series of normal modes at wave zone ranges of an arbitrary emitter, based on using Poisson's approximation summation formula, as a result of which the series of normal modes is transformed to the integral. Inside the Earth-ionosphere waveguide, the integral is evaluated by the stationary phase method, and the field is determined by characteristics of two normal modes. At the ground, the integral is brought to Fock's diffraction formula, which calculates the field in the regions of geometrical shadow and semi-shadow. The computational formulas make it possible to use algorithms and programs of the normal mode approach that were developed for long-range radio paths.