Analysis Of Circularly And Linearly Polarized U Slot Excited Hemispherical Dielectric Resonator Antennas With A Backing Cavity

Today, more and more antenna engineers are viewing the Dielectric Resonator Antenna (DRA) as a preferable alternative to conventional low-gain designs because of several attractive features, including high radiation, light weight, small size and low profile. This practical resource presents complete, up-to-date details on DRAs in a single volume. The book provides professionals with clear guidance on the mode of operation and radiation behavior of DRAs, the main methods of excitation, and the major advances in DRA technology. This hands-on reference equips engineers with simple equations and graphs that help them rapidly design DRAs, without the need for complex analytical or numerical calculations. Numerous design examples are included to give practitioners a sense of the versatility that DRAs afford.

This book introduces 5 key feeding techniques such as coaxial probe, microstrip, conformal strip, aperture, and coplanar waveguide and covers different shapes of dielectric resonator antennas leading to improvement in circularly polarized (CP) performance. It introduces advancements in the field of dielectric resonator antennas and dilectric resonator antennas (DRAs). Five different types of feeding techniques (i.e. coaxial probe, microstrip, conformal strip, aperture, and coplanar waveguide) are described for obtaining CP followed by two modified shaped DRA (sector DRAs). Throughout this book, rectangular and circular with their modified shapes of the dielectric resonator are utilized, providing differing degrees of freedom as well as different variable parameters, including length, width, height, radius, aspect ratio and dielectric constant, which are tuned to obtain the desired antenna parameters.

Recently, the Dielectric Resonator Antenna (DRA) radiating element has been the subject of considerable interest due to its small size and high efficiency. The rigorous analysis of DRA elements, however, has been largely restricted to rotationally symmetric shapes. Other shapes have been analyzed, however, often based on an infinite ground plane assumption which restricts the use of the DRA as a single element for some applications that require finite size ground plane. Various numerical techniques have been used in the analysis of the DRA. The spherical mode expansion was used to analyze a hemispherical DRA. The Surface Integral Equation with the Method of Moments (SIE/MoM) has been used to analyze a rotationally symmetric DRA. The modal expansion method with some approximation was used in to analyze the rectangular DRA, and the Finite Difference Time Domain (FDTD) method has been used to analyze a rectangular DRA and cylindrical DRA with a staircased cell approximation. Here the rectangular DRA is considered over a finite ground plane with a microstrip slot excitation. The SIE/MoM is used with the RWG triangle basis function expansion. Using the triangle basis functions allows modeling of arbitrarily shaped objects. Also, the FDTD method is used to analyze the same problem for the purpose of verifying both methods. The effect of the ground plane size and the dielectric substrate truncation is studied.

The use of dielectric resonator as a resonant antenna was proposed in 1983. Due to the absence of metallic loss, the dielectric resonator antenna (DRA) is highly efficient when operated at millimetre wave frequencies. With the use of high dielectric constant material, the DRA can also be used as a small and low profile antenna operated at low microwave frequencies. Low cost dielectric materials are now easily available commercially, encouraging more antenna engineers to design communication systems with DRAs.

Small satellites are satellites that weight less than 500 kg. Compared to larger satellites, a small satellite, especially a cube satellite, has limited surface area. The limited surface area casts challenges for allocating essential parts, such as antennas, for the satellite. Therefore, antennas that are conformal to the satellite surface have distinct advantages over other types of antennas that need significant mounting area. One of the very effective conformal antennas is cavity-backed slot antennas that can be integrated around solar cells and do not compete for extra surface area. The previous study performed on cavity-backed slot antennas was mainly a feasibility study and did not address realistic concerns such as effective feeding methods for the antennas. This thesis work is aimed at providing more detailed study on achieving high quality circular polarization (CP) and simplified feed design to initiate effective integration of the antenna with solar panel. In order to accurately characterize an antenna, an effective antenna range in an anechoic chamber is important. Utah State University had an effective near-field range; however, there was not an fully shielded anechoic chamber. As another objective of this thesis work, a state-of-the-art anechoic chamber has been constructed, calibrated, and utilized to measure different antenna parameters. This thesis also shows correct methods to measure important antenna properties such as CP and antenna efficiency.

The aim of this work is to study the excitation of dielectric resonator antennas using rectangular waveguide slots and probes. Thus, the advantages of waveguides as feeding structures having low losses at high frequencies and the inherent wideband nature of dielectric resonator antennas are combined, which increases the system efficiency in the microwave range.