F.Vipiana, G.Vecchi, S.Maci, A.Freni, M.Bercigli, M.Bandinelli, M.Sabbadini
Abstract: Current real-life designs involving antennas and EMC in antenna farm issues call for unprecedented levels of complexity, and require accurate, virtual-prototyping predictions, which are best obtained using cutting-edge modelling technology applied in a computational environment that offers a seamless workplace to the antenna engineer from CAD to design verification. Furthermore as predicted results are increasingly used to replace costly tests on hardware models the issue of fidelity becomes more and more important. The new baseline full-wave modelling being developed for ADF-EMS is based on the existing MoM capabilities with the inclusion of: 1) Fast Multiple Method (FMM), both in its single- and multi-level (MLFMA) implementations; 2) Multi-resolution (MR) hierarchic basis functions. The FMM/MLFMA is arguably the most proven and efficient approach for large problems; being an iterative method, the issue of convergence is of paramount importance especially in the presence of geometrical (structural) complexities. In this regard, the MR is a technique that allows a tight control of the conditioning of the MoM matrix in complex environments. Separately and in combinations, these techniques allow stable, fast and accurate solutions for complex problems with minimal intervention on the part of the user. At the same time ADF-EMS offers PO/ITD and UTD capabilities allowing the selection of the best modelling strategy for different aspects of a same problem. One specific problem of antenna farm modelling is the virtually unbounded error toward low field levels. Often predictions show deep nulls in the field that are seldom observed in reality and are due to the assumption of perfect specular reflections on the satellite body.
Published on 30th ESA ANTENNA WORKSHOP, Noordwijk, The Netherland, 27-30 May, 2008