Uneven terrain in an airport affects the performance of an instrument landing system(ILS)

hence a simulated prediction method for evaluating ILS glide slope performance based on multi-wedge model of uneven terrain is proposed

where the uniform theory of diffraction(UTD)is adopted to establish a basic propagation model for ILS glide slope signal in space. A scanning-search algorithm is used to ray-trace the multi-wedge model for uneven terrain and to get the complex electromagnetic field in space

and the acceptability of the terrain effect can be evaluated according to the specified order of rays. Evaluation of the ILS glide slope in practical airport environment is performed with the proposed method

and the results show that accurate and effective predictions for ILS glide slope performance can be realized

and the prediction results are closer to flight inspection when the effect of higher order rays are considered.