Miniaturização de antenas de microfita para aplicações em CubeSats

Abstract

The objective of this work was to develop a compact microstrip antenna for use in CubeSats, a type of miniaturized satellite used mainly by universities for space exploration and research, typically in low earth orbit. The small size of these satellites presents a great challenge to the project. Being one of the main components on board satellites, the antenna determines the performance of all wireless systems, including: telemetry, tracking and control (TT&C); downlink of high speed data; navigation; communications between satellites; radars; and sensors. For the TT&C function, expandable wire antennas are often employed in V-UHF. However, the release mechanism of these antennas can fail and compromise the mission. A microstrip antenna has several advantages such as reduced size, low weight and absence of mechanical parts. Therefore, a compact microstrip antenna is desirable in this type of application. The work presents a bibliographical review covering some concepts about the CubeSat pattern, the fundamentals of antenna theory, the main techniques of miniaturization of antennas, the fundamentals of electrically small antennas and the main works already developed on the subject. An additional investigation was carried out on Wheeler’s method for measuring the radiation efficiency of compact antennas, this method being applied to measure the radiation efficiency of the built prototype. The work methodology consisted of designing, simulating, building and characterizing a microstrip antenna operating at two frequencies (401.6 MHz and 435.0 MHz) based on the fundamentals of the literature review. These frequencies were chosen to meet the requirements of most CubeSats in use, but in particular they serve two of the frequencies planned for CONASAT, a project by the Northeast Regional Center (CRN) of the National Institute for Space Research (INPE), located in Natal, in partnership with the Federal University of Rio Grande do Norte (UFRN). To confirm the applicability of the developed prototype, a complete characterization of the link was carried out considering all the gains and losses involved. The contribution of this work lies in the ability of the developed prototype to operate at two frequencies with a single power point, thus reducing the weight, complexity and risk of failures in the CubeSats communication systems.