Research on Near Field Signal Behaviour of Localizer Antenna System

Abstract

Near-field (NF) signal distribution behavior with a radius of 150 meters was studied to compare with far-field (FF) distribution characteristics. It can be found more flexible and detailed in NF than the signal from an NF monitor with only a single location. The origin of the measured value and signal detection method on the equipment was introduced in detail. The three-dimensional model was established and optimized by phase analysis as well as the measured data on-site. There was little difference between a measured distribution and a theoretical calculation in space. The change of directional weakening of the Log Periodic Dipole Antenna (LPDA) was proposed. Unequal amplitude signal synthesis together with Fresnel loss was considered to research and explain the incredible power gain. The modified 3D model is in good agreement with the measured results.