Bandwidth Enhancement of Dielectric Resonator Antennas using Stacked and Fractal Geometries

Abstract

In recent times, the Dielectric Resonator Antennas (DRAs) have shown great potential newlineas an alternative to microstrip patch antennas in various practical applications. Their newlineinherent properties like wide bandwidth (BW), high gain, low losses, high mechanical newlinestrength, high power handling capacity, three degrees of freedom, compatibility with newlinediverse feeding techniques, and many more make DRAs the preferred choice over newlinemicrostrip antennas. newlineVarious techniques have been employed by the researchers for bandwidth improvement newlineof Dielectric Resonator Antennas. This thesis focusses on the concept of using fractal newlinegeometry, stacking and a hybrid of fractal geometry and stacking for achieving wide newlinebandwidth. Various novel DRA designs with wideband and ultrawideband (UWB) newlineperformance have been proposed. The proposed antennas have been analyzed using a newlineFEM-based EM simulator Ansys HFSS. The prototypes have been fabricated and their newlineresults compared with simulated results to validate the designs. Further, it was found newlinethat very little work had been carried out in the field of mutual coupling isolation in newlineultrawideband DRA array. Using novel Defected Ground Structures (DGS), reduction newlinein mutual coupling in different DRA array designs has been achieved. newlineIn the first approach to enhance the bandwidth of DRAs, two novel fractal-based DRA newlinedesigns have been proposed. The use of fractal geometry also offers the benefit of newlineantenna miniaturisation. The first design is a Triangular Prism-shaped DRA with newlineSierpinski Gasket fractal geometry. An impedance bandwidth of 72.3% has been newlineachieved in this prototype. Secondly, the design of the innovative Surya Yantra-shaped newlinefractal UWB DRA has been proposed. Measured impedance bandwidth of 113.3% newlinecovering the frequency range from 2.6 to 9.4 GHz has been achieved. newlineIn the second approach, two novel DRA designs based on the concept of stacking have newlinebeen proposed. Apart from bandwidth improvement this approach also provides the newlinebenefit of high gain. Stacked T- and Z-shaped DRA designs hav