Wideband Dual-Polarized Patch Antennas And Array Antennas

With the rapid development of the fourth wireless communication technology, thenumber of the communication users is increasing quickly. In order to broaden thecapability of the communication system and solve the problem of multipath fading,antennas in the mobile communication base station system should have remarkableadvantages, such as dual polarization, wide operation band and multiband performance.Based on the practical requirements of the fourth communication system, this thesismainly investigates the wideband electromagnetic-fed dual-polarized antenna,broadband dual-polarized magneto-electric dipole antenna, multiband printed antenna,and dual-polarized antenna array. The author’s major contributions are outlined asfollows:1. Wideband electromagnetic-fed dual-polarized patch antennas have been studied,electromagnetic feeding structure is proposed for the dual-polarized patch antenna.Firstly, by loading slots in the radiation patch of the novel patch antenna using probefeed, a wideband electric-fed linear-polarized antenna element is presented. Theequivalent circuit of the antenna is analized by the curve fitting method. Secondly, amagnetic loop is used to feed the antenna, and the wideband magnetic-fedlinear-polarized patch antenna is proposed. The equivalent circuit of the antenna is alsostudied carefully. On the basis of the above-mentioned research, an electromagnetic-feddual-polarized patch antenna is designed. Then, a meander probe is adopted, and abroadband electromagnetic-fed dual-polarized patch antenna is designed. Finally, bycombining the differential excitation structure with the magnetic loop, a widebanddual-polarized patch antenna with high isolation is achieved.2. Broadband dual-polarized magneto-electric dipole antennas have been studied.Firstly, by combining bow-tie electric dipole with the L-shaped magneto dipole, abroadband magneto-electric dipole bow-tie antenna is proposed. Secondly, a differentialexcitation inverted L-shaped structure is introduced to reduce the cross-polarizationlevel, and a wideband magneto-electric dipole antenna with good radiation pattern ispresented. Based on research above, a wideband differential-fed dual-polarizedmagneto-electric dipole antenna and a hybrid-fed dual-polarized magneto-electric dipoleantenna with high isolation are designed, respectively. The effect of the important parameters on the antenna performance is analyzed carefully. The experimental resultsshow that these designed antennas have stable directional radiation properties, whichmake them good candidates for mobile base station system.3. Broadband dual-polarized and multiband printed antennas have been studied.Firstly, by combination of the coplanar waveguide feeding structure and the microstripfeed line, a broadband dual-polarized printed antenna is proposed. Then, with the use ofdifferential feeding structure, a dual-polarized printed antenna with high isolation isachieved. Secondly, based on the traditional slot antenna, a dual-band printed slotantenna with parasitic strip is presented. In addition, by etching two triangular notcheson the ground plane, a dual-band printed patch antenna is proposed. Finally, with theuse of electromagnetic band-gap structure, a tri-band circular slot patch antenna isdesigned. All the proposed antennas are printed on the single substrate, which aresuitable for modern wireless communication system.4. Multiband dual-polarized array antennas have been studied. According to thenovel printed dipole antenna, a dual-band dual-polarized antenna element is presentedfirstly with the multi-layer coupling feed structure. Then, taking advantage of themutual coupling between the antenna elements, a tri-band dual-polarized4-elementarray antenna is proposed. Finally, by etching slots on the ground plane, a dual-banddual-polarized array antenna with high isolation is designed. The designed antennashave good performance, which can meet different application requirements.