Redes de antenas dielétricas ressoadoras de quarto de cilindro para operação nas bandas L e S

Abstract

This work presents the design and development of quarter-cylinder dielectric resonator antennas to compose two planar antenna arrays: one operating in S-Band, at 2.26 GHz, and another operating in L-Band, at 1,575 GHz. The work begins with the description of the scenarios to which the presented designs can be applied. Then, a literature review on the fundamental concepts of antennas, characteristics of dielectric resonator antennas and on the requirements for the CONASAT and GPS systems are addressed. In Chapter 3, the application of a heuristic method known as differential evolution (DE) to optimize linear arrays of microstrip antennas is presented. This method was chosen because it has not been widely used for antenna array optimization yet. Also, the technique has not been studied in Laborat ́orio de Eletromagnetismo, Micro-Ondas e Antenas (LEMA) of Universidade Federal do Pampa up to now. It is demonstrated that the application of DE was effective for the synthesis of linear antenna array, in which the main lobe of the radiation pattern should point to a desired direction, while the side lobe level should be kept below a specified threshold. In order to obtain a compact geometry, in Chapter 4, miniaturization techniques are applied to reduce the physical size of the cylindrical dielectric resonator antenna. The methodology used for the design of the antennas consists, initially, on an electromagnetic modeling of the radiating element in an electromagnetic simulator. After application and validation of the antenna miniaturization techniques with simulations, a compact quarter-cylinder geometry is obtained. For the design of S-Band and L-Band antennas, the use of a discrete element at the top of the antenna has been investigated, to ensure the impedance matching. This technique is analyzed through a parametric study that is used to find the nominal values of the components that allow achieving proper impedance matching. The designed single elements are used to compose planar antenna arrays. For the S-Band array, a feeding system based on hybrids implemented in stripline technology was developed. In Chapter 5, experimental results concerning the work are presented. A thru-reflect-line (TRL) calibration kit is developed to enable the experimental characterization of the inductors needed to manufacture the S-Band and the L-Band antennas. Finally, prototypes of the quarter-cylinder dielectric resonator antennas are shown and the experimental results are presented and discussed. The main contribution of this work is the demonstration of the systematic design of a quarter-cylinder dielectric resonator antennas, including their use for communication systems installed onto nano-satellites. Key words: Dielectric Resonator Antennas, Antenna Array, Optimization, GPS, CONASAT.