Structure scattering analysis for SeaWinds Scatterometer reflector antenna using extended aperture integration and GTD

One of the major considerations of antenna design for spacecraft application is the complex structures around the antenna which can become scatterers due to significant illumination from the antenna. The resulting scattered fields can interfere with the direct antenna radiation pattern and cause degradations in the antenna directivity and sidelobe levels. A good example is the NASA SeaWinds Scatterometer designed for the Japanese ADEOS II Spacecraft. The scattering effect caused by the spacecraft structures can be analysed by using the geometrical theory of diffraction (GTD) ray tracing approach. One alternative approach to the problem of the equivalent dipole sources is to use the extended aperture integration (AIE) method for the forward scattering analysis when the structure is close to and in front of the antenna aperture. The authors determine the scattering effects to the antenna performance due to the presence of the various box structures. With the resulting information, one can determine better locations and sizes for the structures such that they will not cause significant degradation to the desired antenna performance. Results are presented for the SeaWinds reflector antenna using the AIE method and for the plate scattering analysis of the OSU Reflector Antenna Code.<>