Efficient MoM simulation of 3-D antennas in the vicinity of the ground

A novel fast technique is presented to account for the effect of an arbitrary soil permittivity in the analysis of ground penetrating radar antennas in the presence of a flat layered ground. We named the method fast ground coupling matrix because it is expressed as an additional method-of-moment (MoM) impedance matrix obtained from the radiation patterns of the basis/testing functions and the ground reflection coefficient. The advantage of this method is the independence of radiation patterns from the ground’s physical and electromagnetic parameters (layer thickness, complex permittivity, permeability, and so on). The new matrix formulation efficiently calculates the impedance matrix due to the ground’s contribution, with a loop over the ground parameters (permittivity, conductivity, and/or permeability), and changing the distance between antenna and ground. The number of samples in (complex) spectral domain is dramatically reduced by explicitly compensating truncation with aliasing errors in the spectral integration. To demonstrate the accuracy and efficiency of the proposed method, numerical results for 3-D metallic Vivaldi and typical dipole antennas are presented. Good agreement among the exact MoM solutions, the simulation results, and measured data is observed over an ultrawide bandwidth.