Elevated Duct Effects on Radar Ranges Using an Airborne Microwave Refractometer

Abstract

Anomalous distribution of humidity and temperature in the troposphere is responsible for significant changes in electromagnetic wave propagation and results in enhancement/degradation of radar ranges, elevation errors etc. The present investigation assesses atmospheric refraction effects in the tropics by producing radar ray traces which depict the path of the airborne radar rays using a three-dimensional ray tracing technique combined with the radio refractivity vertical profile derived using an airborne microwave refractometer. The radar rays at the target can be represented as a sum of normal modes and an assembly of rays reflected from the elevated ducts/layers. The radar range errors at small elevation angles are evaluated.