Design and Development of Dielectric Resonator Antennas

Abstract

In today’s wireless world, antenna is of prime importance. Antennas are used in variety of applications right from the deep space missions wherein large size gigantic antennas are required for transmission and reception at the earth stations to the miniaturized versions of antennas used in small remote sensor nodes, hand held devices, military purposes. Now-a-days extremely small antennas along with the capability of providing high gain, high bandwidth and reconfigurable beam scanning properties are required. Dielectric Resonator Antenna (DRA) is a recent topic of interest among researchers worldwide. DRAs prove to be a better alternative in comparison to microstrip patch antennas, especially for high frequency applications. DRAs provide high gain, minimum conduction losses, and wide bandwidth, while maintaining compactness of the antenna. Wide bandwidth is one of the major advantages of using DRAs. There are multiple ways of achieving wide bandwidth. Stacking of DRAs, insertion of air gap, implementation of fractal geometry are few of the techniques to achieve wide bandwidth. Combining different antenna types is a promising way to get benefit of each antenna type and overcoming the trade-offs of each individual antenna type. This thesis report discusses the advantages, unique properties and novel designs proposed in the field of Dielectric Resonator Antennas. Four novel antenna designs have been proposed in this thesis. Different bandwidth enhancement techniques mentioned above have been utilized in the proposed designs. Use of fractal geometry to achieve wide bandwidth has been made in the first three proposed designs, while the last design is based on the concept of stacking and air gap insertion. First design proposed is a Prism Shaped DRA. Three different prism shapes namely, octagonal prism, hexagonal prism, and cuboidal prism, each with two fractal iterations have been simulated and a comparison of return-loss performance has been made. Bandwidth about of 57.5% with respect to 10 GHz resonating frequency has been achieved. The proposed antenna was fabricated and its results were verified. Second design is a combination of two different fractal designs implemented on tetrahedron shaped DRA. Sierpinski Gasket and Koch fractal geometries have been combined to achieve wide bandwidth of about 70.13%, covering frequency range from 8 to 16.8 GHz. To minimize the cross-polarized radiation, stacking of DRA and novel feeding technique has been proposed. The antenna was fabricated and its results were verified. Both these antenna types have been designed for X-band applications. Third design is a Tree Fractal DRA. This antenna has been designed for C-band and provides about 86.32% BW along with high gain and improved radiation pattern. The proposed design is very compact. Lastly, one more proposed design named Hybrid T-shaped DRA has been discussed. This antenna has been designed for ultrawideband applications. Conformal strip feeding has been used to achieve proper impedance matching. This antenna has been designed for UWB application with measured bandwidth of about 110.5%, covering frequency range from 3.35 to 11.6 GHz. The antenna was fabricated and its results were found in accordance to simulated results. \\included in this report.