An estimate of the modified refractive index from the received field strength

A method of estimating the refractive index distribution is suggested from the height gain profile of the received electric field strength which is ge nerated due to the inverted atmosphere as a surface-based duct or an elevat ed duct. First, an initial value of the refractive index distribution is gi ven by applying the height gain profile at one spot to the wave equation. N ext, the height gain profile at another spot is derived from both the recei ved electric field and this refractive index by the split-step method, and the refractive index distribution is modified by comparing it with the heig ht gain profile measured at the spot. The bilinear model and 2n power N pro file model are adopted as the atmospheric models to evaluate the method of estimating this refractive index, and numerical examples of the refractive index distribution to be derived from the altitude distribution of the rece ived electric field with each model are presented, and are considered simul taneously. (C) 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(7): 40-49, 2000.