A Method to Determine an Effective Radio Refractivity Profile by Direct Radiometric Measurements

摘要

A vertical reflection interferometer may be used to record the signal received from an airborne source. As the source rises in height a multipath fading pattern is produced. At each ordered fade the experimental geometry can be used to determine a value for an effective earth radius. It is shown that each value of earth radius can be related to an effective refractivity gradient with height from which the refractivity profile can be constructed. The experimental procedure is based on the results of a comprehensive radio propagation experiment performed at Cold Lake, Alberta, from which it was determined that the effective earth radii could be measured to plus or minus 200 nm average using radiometric methods only. (Author)