Development of Advanced Design Software for Complex Multimode Antenna Feeding Systems

Ka-band multiple-beam spacecraft antennas (MBA) are a key technological challenge in the design of broadband communication-satellite systems. Due to the very narrow beamwidth of multiple-beam spacecraft antennas, beam pointing is a critical issue, since even very small pointing errors can seriously affect the antenna's performance. Consequently, many of these communications antennas require closed-loop tracking. While full-wave design tools for multimode waveguide components have been well established since the mid-1990s, there was a perceived lack of similarly powerful design tools for multimode horn radiators. In order to close this technological gap, the European Space Agency (ESA) proposed a sponsored research effort, focusing on the development of multimode horn design software. The project was executed by a team consisting of MDA Satellite Systems, Canada, and Mician GmbH, Germany. While the software-requirements specification and its validation was the primary responsibility of MDA, Mician was responsible for the software implementation. This paper summarizes the work performed under this project, and also provides examples of complex multimode feed designs for multiple-beam spacecraft-antenna applications.