Innovative representation of antenna measured sources for numerical simulations

Placement analysis in complex antenna scenarios require accurate computational electromagnetic (CEM) tools. A fundamental requirement to achieve truthful results, is that the source antenna must be accurately modelled. However, in many practical cases, a full-wave representation of the physical antenna is unfeasible or unavailable in the format required by the desired CEM solver. This paper describes a procedure to derive, a computational efficient, full wave representation of an existing antenna for CEM solvers. The procedure is based on post-processing of the measured antenna pattern. The desired source antenna is measured while situated in a suitable environment, of reduced complexity and size, that locally resemble the final antenna environment. The measured field is expanded using equivalent currents and an equivalent near field (NF) source is derived in a volume conformal to the antenna. The NF source is a truthful representation of the measured source and highly suitable for CEM analysis. The procedure of generating the NF source from measurements is fully general and can be used for the installation of antennas in complex environments of arbitrary complexity. The procedure is illustrated and validated by an example concerning the placement of a monocone antenna (SMC2200) on an electrically large rectangular ground plane. The monocone antenna is initially measured on a small circular ground plane that resemble the final operational environment in the vicinity of the antenna. The measurement has been performed in a MVG multi probe spherical near field system. Simulations using the measured source on the larger rectangular structure have been compared with a full numerical model of the antenna and structure for verification. A further validation of the NF source method, based on the measurement of the larger rectangular structure is on-going.