Dielectric Resonator Antennas And Wideband Planar Antennas

With the spectrum resources being developed and applied, the techniques of wideband, miniaturization and dual-polarization are increasingly important in the wireless communication system in the future, especially for national economy and military applications, such as the satellite communications, electronic warfare systems, etc. Thus this dissertation proposes the novel designs of wideband and dual-polarization dielectric resonator antennas and ultra wideband (UWB) and circular-polarization planar antennas with experimental verification. Four main subjects are included:Firstly,A kind of U-shaped dielectric resonator antennas is proposed. The resonator modes of this dielectric resonator configuration are anslyzed in theory, and two patch-fed structures are studied. From the experiment results, the elliptical patch-fed and inverted trangle-fed U-shaped dielectric resonator antennas have 72% and 84% impedance bandwidths, respectively. These bandwidth performances keep advanced level in the world.Secondly, a high-isolation dual-polarization dielectric resonator antenna is developed. By using the symmetry feed and the anti-phase feed technology, the level of port isolation and the cross-polarization level both of the dual-polarization dielectric resonator antenna are improved. The measured isolation between two ports are higher than 42dB, and the measured cross polarization level in the main lobe is less than -21dB, which are being the advanced level in the available international literature. In addiation, an S/X dual-band dual-polarization hybrid array of dielectric resonator antenna and microstrip antenna is designed.Thirdly, the omni-directional ultra-wideband planar monopole antenna is developed. By analyzing the effect of the shapes of radiation patch and feed structure to the radiation pattern, the rectangular patch and the dual-feed structure are proposed for improving the omni-directional characteristic. At the same time the tunning stub embedded in the microstrip feed line is proposed to realize the band-notch. From the simulated and experiment results, the proposed antenna achieves the good omni-directional radiation performance. Fourthly, the L-shaped stub-fed circular-polarization fractal slot antenna is proposed, and the one-order and two-order fractal rhombus slot antennas are analyzed. One-order fractal rhombus slot antenna has a wider impedance bandwidth of 50.4% and AR bandwidth about 13.3%(4.9GHz-5.6GHz), comparing to that of the slot antenna without fractal structure. Under the same circumstances of the same resonance frequency, two-order fractal slot antenna has smaller size, with 67% size reduction compared with the one-order fractal antenna.