| With the development of high-speed communication as well as the integration and miniatur-ization of military and commercial equipments, there has been a higher demand on antennaperformances, and the study on ultra-wideband printed antennas has become much focusedon. In this thesis, ultra-wideband planar wide-slot antennas, planar spiral antenna with back-cavity and microstrip arrays have been studied. Several novel designs have been proposedand partially verified by experiments. This thesis consists of the following parts:Firstly, an overview of the application of ultra-wideband technologies and the advancesin ultra-wideband slot antennas and planar arrays is given. The electromagnetic simulationmethods used in this study are also brie?y described.Based on the known arts, elliptical slot antenna and rotated elliptical slot antenna withtapered microstrip feed and circular excitation patch are proposed and analyzed. Ellipticalslot antenna with tapered CPW feed and elliptical patch have also been proposed. They haveachieved impedance bandwidth of above 174%. Parasite patch has been loaded to the slot topromote the gain and adjust the radiation pattern. Furthermore, 3 kinds of novel widebandcavities have been proposed to use with the wideband antennas with bi-directional radiationpatterns, to reach a wideband impedance matching and uni-directional radiation.Besides, as to improve the impaired radiation efficiency due to the application of wave-absorbing materials to planar spiral antennas, a parabolic back cavity is proposed to use withtapered coaxial line as the balun. The nice impedance bandwidth of 0.36 6.83GHz, anratio of 19:1 has been achieved with compact size.Finally, based on the project application, 2 kinds of microstrip arrays for Ku band havebeen designed. The features of rectangular suspended microstrip antennas are studied, andseveral novel feeding structures were proposed to realize a 4 4 high-gain array; accordingto the specific requirements of the project, a 4 8 array of rectangular patch elements withsatisfactory performance has been designed. |
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