Analysis and Design of Next - Generation Ground Stations

This thesis, developed at the Antennas and Microwave Laboratory of the University of Pavia, focuses on the design and analysis of a new generation of ground stations related to the evolution of space exploration. On one hand, the frequency bands used for space communications, both for data transfer, telemetry and commands, are higher than in the past: we are transitioning from the historical S and X bands to the K and Ka bands. On the other hand, space exploration, both human and robotic, is expected to reach further and more consistently than in the recent past. Therefore, it is necessary to develop ground stations capable of supporting radio links for the transmission of the constantly increasing amount of data required from future space missions. These missions can include both deep space robotic missions (i.e. JUICE) and potential human settlements on the Moon. Specifically, this thesis describes the work done on two main projects: the first involves the design of a new antenna of the European Space Agency for deep space communications, while the second concerns a possible design for a ground station intended to maintain contact with future lunar missions. NNO3 (New Norcia 3) is a project funded by the European Space Agency and carried out by a consortium of European companies to develop a new Deep Space Antenna in Australia, able to operate at the X, K, and Ka frequency bands. NNO3 marks the first step in a process that will double Europe's capabilities to support deep space missions. Moreover, it is also the first time, after the construction of the first European Deep Space Antenna in the late 1990s, that the entire antenna design restarts from scratch with the intent to improve the actual performance thanks to technological advancements of the last two decades. In particular, the thesis follows the various stages of development of the antenna optics and its performance, also considering the realization of specific structures such as dichroic mirrors, struts and their consequent impact on the antenna behavior. Additionally, the thesis includes the design of a system for aberration induction at the high frequencies of the Ka band, where the main lobe of the antenna radiation pattern is extremely small (about 17 millidegrees). This characteristic, combined with the huge distance from the Earth of the probes exploring the solar system, makes necessary the separation of the transmission beam from the reception one in order to avoid extremely high pointing losses that would make the communication link impossible. The thesis also provides insights into some topics that, due to the timeline of an industrial project, were not included in NNO3 but could lead to further improvements if applied to future Deep Space antennas and properly developed. The second project addressed by the author in this thesis involves a study for a possible design of a ground station intended for lunar communications. Currently, there is a rapid increase in interest towards our satellite, and numerous missions are expected in the coming years with the goal of bringing the human being back on the Moon surface, possibly for extended periods of time as it is now a standard situation on the International Space Station. This requires a ground segment that meets the needs of these new milestones in space exploration and thus the design of more high-performance and reliable antennas. Specifically, the design of a dual-reflector antenna based on a ring focus configuration that can operate across three different frequency bands (S, X, and K) is reported. Various analyses are presented and discussed along with the obtained performance.