Research On The Design Of Critical And Sensitive Areas Of Instrument Landing System

The Instrument Landing System(ILS)is a precision approach landing system widely used globally which has played an important role in civil aviation since 1947.The critical area and sensitive area of ILS are areas set up to ensure the ILS operate safely.China always divides the areas according to the standards in Aeronautical Telecommunications Annex 10 to the Convention on International Civil Aviation("Annex 10")issued by the International Civil Aviation Organization(ICAO).Researches on critical and sensitive areas of ILS in the world are very rare,and their classification standards are constantly being updated,so it is necessary to find a theoretical basis to support them.Firstly,the current research status of ILS at home and abroad is introduced and the working principle of ILS is analyzed.Antennas models of ILS localizer(LOC)and glide slope(GS)are established and the formation principles of their radiation field are studied.And then,the critical and sensitive areas of ILS are introduced.Next,the operating environment and signal propagation method of ILS are studied.According to the nature of interference sources,the electromagnetic interference of ILS is mainly divided into active interference and passive interference and this article mainly analyzes the passive interference received by ILS during the actual operation.The influence of multipath effect on ILS signal is analyzed by using Geometric Optical(GO)method and Uniform Theory of Diffraction(UTD).Besides,The Tamir forest model is used to analyze the influence of environment on ILS radiation field,with emphasis on the impact of different obstacles in the environment on DDM,so as to obtain the influence of environment on the design of critical and sensitive area.Finally,taking the ILS/DME approach procedure of 36 R runway of Beijing Capital Airport as an example,the Fresnel principle and the Tamir forest model are both used to perform simulation experiments to obtain its ILS critical and sensitive areas.And then compare the result with the standards in Annex 10.