This letter presents a novel 3-D hybrid method for instrument landing system (ILS) channel modeling, which names half space multilevel fast multipole method - parabolic equation method (HSMLFMM-PE). The multilevel fast multipole method (MLFMM) is applied to simulate the source region and near source obstacles. The large scale obstacles, pertaining to the far field region, is implemented by the parabolic equation (PE) method. The transition plane between the MLFMM region and PE region is solved by the half plane Green’s function of the MLFMM to avoid the full wave simulation of the ground, thus the computation cost can be further reduced. Experimental results demonstrate that the computation cost of half space method is lower than full space method. The HSMLFMM-PE method can simultaneously meet the requirements of high simulation accuracy and the requirements of large area radio wave propagation computation in ILS simulation.

The aircraft’s landing is guided by the instrument landing system (ILS). However, the guidance information may be disturbed by reflections from irregular terrain and obstacles. A sketch which restrains the multipath effect from irregular terrain and obstacles, is then required. This paper proposes a metallic reflective structure which aims at blocking the radio wave directly radiating to the terrain. The design of the structure size and location is based on the location of the obstacles and the radiation pattern of the antenna. Due to the fact that the scattering effect of the structure should be accurately simulated, the finite difference time domain - parabolic equation method (FDTD-PE) is applied in ILS and used to simulate the interaction of the scattering effect between the structure and the terrain. The experimental results show that the proposed method improves the multipath effect mitigation.