Modelling the effects of realistic environments in the nearfield and farfield of Low Frequency Antennas with 3D FDTD method

Abstract

Ground wave radiation of Low Frequency Antennas is well known for the canonical case of a flat, azimuthally homogeneous, soil. In this paper, more complex kinds of environment are considered in the surroundings of the antenna or in the far field. Both of them are treated by FDTD. Some realistic environments are studied in the near field zone including forest and slopes. An original methodology is proposed for the far field zone. It rests on the use of the direct numerical integration of Sommerfeld's integrals which is presented also.

3D‐FDTD‐based hybridisation technique for wave interaction with scatterers in layered media

“…The FDTD computation space is a 100 cells side cube with the mesh size Δx = Δy = 25 m and Δz = 75 m. The ground surface ( z = 0 m) is located at the middle of the z ‐directed cells. The incident electromagnetic field in both the air and the ground is computed by a numerical integration of Sommerfeld's integrals with an adaptive algorithm [8]. These values are applied on the Huygens’ surface surrounding the receiver.…”

“…The parameter α is chosen by the user such that the signal has reached its maximum amplitude after a few initialisation periods. The incident electromagnetic field in both the air and the ground is computed by a numerical integration of Sommerfeld's integrals with an adaptive algorithm [8]. These values are applied on the Huygens' surface surrounding the receiver.…”