Broadband dielectric resonator antennas for WLAN applications

Today's communications systems require use of broadband antennas to meet high capacity requirements. Furthermore, some applications require smaller antenna sizes. In this work, a broadband Dielectric Resonator Antenna (DRA) for WLAN applications is presented. The antennas presented are compact in size, have the broadside radiation patterns and high radiation efficiency. The bandwidth of the DRA depends on the dielectric material, its shape, as well as the excitation technique used to feed the antenna. The three antennas presented in this thesis are of half cylindrical shape, mounted on ground planes and excited by aperture coupling slot. A parasitic U slot is part of the feeding network for more coupling and bandwidth enhancement. The antennas have good radiation characteristics and operate over a wide band of frequencies. Ansoft HFSS is used for the antenna simulation. CST Microwave studio is also used to compare the accuracy of time domain and frequency domain analysis of the DRAs. The DR material is Rogers RO3010 (TM) with [varepsilon] r = 10.2, and a dielectric loss tangent of 0.0035. The substrate material is Rogers RT/Duroid 5880 (TM) with [varepsilon] s =2.2, a loss tangent of 0.0009, and 0.767 mm thickness. The half-cylindrical DRA is used to have the TEo13 mode excited. The radiation patterns of the three antennas are similar to that of a magnetic monopole which has the broadside radiation pattern. Parasitic U-shaped slots are used with the three presented antennas to enhance the bandwidth by exciting a dual resonant frequency in the TE 01e mode. These slots have similar radiation characteristics to those of the half cylindrical DRAs so the overall radiation patterns of these antennas are not deteriorated. For the fabricated antennas, they have broadside radiation characteristics in H and E planes. As for the impedance bandwidth, the half cylindrical ORA has 24 % fractional bandwidth. For the half cylindrical ORA backed with a rectangular dielectric resonator, 32% bandwidth is achieved. A bandwidth of29% is achieved in the case of half volume Elliptical ORA. The gain of the three antennas slightly changes around 5 dBi which is good for the WLAN applications