Numerical simulations of spacecraft antenna systems are more flexible than rheometry for the investigation of movable devices and changes of spacecraft parts. Therefore we devised an antenna toolbox for the analysis of spacecraft antennas. The antennas and the whole spacecraft is represented by a wire grid model. The numerical calculation is based on the reaction integral equations for the wires to get the behavior for transmission, from which the reception properties are obtained by applying reciprocity principles.

As a first application the RPWS antennas onboard the Cassini spacecraft were investigated in detail, with emphasis on the influence of specific parts of the spacecraft on the direction of the effective antenna axes. In the figure the three RPWS antennas are straight wires extending from the spacecraft body in three different directions towards the figure frame. For instance, it was shown that the magnetometer-boom has a very high influence (in figure: long rod of triangular cross-section extending from the spacecraft body to the right bottom). The results of these calculations are in good agreement with the method of rheometry (where the boom was included, but its influence not determined). Furthermore, the results were confirmed by inflight-calibration, utilizing well-known Iovian radio emissions.