Antennas everywhere - from space to undersea - design, optimizations and new techniques for spaceborn, ground based and marine antennas

摘要

The present dissertation gathers the most significant researches and achievements of its author in the antenna domain. The text is organised in three main parts that are intended to guide the reader through a theoretical and technological excursus on antennas solutions, from space to undersea.udEach part aims at showing the answer to each of the following questions, respectively:udHow a spaceborne antenna shall be?udHow a ground-based antenna shall be?udHow a media penetrating antenna shall be?udIn the frame of a collaboration with the European Space Research and Technology Centre (ESTEC) of the European Space Agency (ESA), the author has been involved, after completing on site (in The Netherlands) his M.Sc. degree in 2011, in a research on the optimisation of the scanning properties of confocal dual reflector antenna systems for spaceborne applications.udAs part of his permanent assignment, since 2012, as consultant at the ESA’s European Space Operations Centre (ESOC), Germany, the author is responsible of different sustaining and investment projects on existing and new ground antenna terminals for space missions. Some of the projects are presented in this work.udTogether with the group of electromagnetism of the University La Sapienza of Rome, the author has treated problems related to the electromagnetic deep penetration of lossy media using deep penetrating new antenna solutions.udThe text is organized into five chapters. Chapter 1 is an introduction and deals with the historical background of modern antennas technologies and layouts and with the fundamental parameters for the analysis of antenna systems related to space and terrestrial contexts. Chapter 2 presents the major achievements of a study on a dual confocal offset antenna configuration for space applications. In particular the optical aberrations caused by the offset arrangement are analysed in order to validate the system introduced as an interesting solution for compact, light and simple payload antennas. Chapter 3 introduces to the world of ground based antennas and provides some interesting hints on a wide range of ground antenna types. Several designing solutions are proposed with the aim of optimizing the desired available gain for the various applications, from the tracking of a space launcher to the communication with spacecraft at the edge of the solar system. An in-depth study is presented on the upgrade of a radio telescope into a ground terminal for the support of deep space missions, addressing to the required versatility of the antenna layouts and to the sustainability of the ground station environment. In Chapter 4, the possibility of achieving the electromagnetic deep penetration of lossy media is analysed. A new design solution, able to generate inhomogeneous waves, similarly to what performed by leaky wave antennas, is introduced. This layout is of extreme interest for its flexibility and for its potentiality of application, as for instance the deep penetration of seawater. Chapter 5 recaps the conclusions of the entire dissertation showing that the world of antennas is much wider than one may think at first sight and innovative solutions are always behind the corner.