NMM3D FULL WAVE SIMULATIONS OF VEGETATION AND FOREST EFFECTS IN MICROWAVE REMOTE SENSING

In this paper, we develop a hybrid method combining T matrix of single objects and Fold-Lax multiple scattering theory (FL), for full wave simulations of vegetation/trees. The hybrid method of solving the Maxwell equations consist of off-the-shelf technique for single objects (e. g. HFSS) and newly developed techniques. The newly developed techniques are the three key steps of the hybrid method: (1) extracting the T matrix of each single object, (2) numerical wave transformations and (3) solving the coupled wave interaction equations (i.e. FL) for all the objects. For step (1), we extract the T matrix of a single object by numerical integration with the use of HFSS which is a 3D full-wave electromagnetic field simulation tool. The method of T matrix extraction from HFSS is verified by comparison with the analytical solution of a sphere. The method is applicable to find the T matrix for complicated object where the analytical solution is not available. Then, the wave transformations are performed based on the translation addition theorem. Numerical methods of calculating the transformation coefficients are developed. Finally, the wave interactions among the single objects are accounted for by FL. The results of the hybrid method agree with those of the HFSS brute force method. In comparison, the hybrid method is much more efficient than HFSS for vegetation scattering and applicable to large problems such as full wave simulations of a tree.