| In recent years,with the rapid development of the wireless communication technology,it is a very prominent demand to achieve wireless communication devices with high performance.The capability of the antenna is one of the key factors of the property of the wireless communication devices.Meanwhile,the data transfer rate has been further improved by the development of the wireless communication devices.Considering that different requirements of wireless communication systems,taking full advantages of the circularly polarized(CP)antenna,this paper investigates the multiband CP antennas and wideband CP antennas.The author's main contributions are outlined as follows:Firstly,this paper expatiates on the research status and practical background of the multiband and wideband CP antennas by consulting lots of literatures.Then the basic theories of microstrip antennas,monopole antennas and CP antennas are presented in detail,which can provide fundamental basis for the part of antennas design.Secondly,multiband CP antennas are investigated,and two kinds of multiband CP antennas are proposed.(1)By stacking two asymmetric arc-shaped cornet-truncated square microstrip patches,a compact dual-band CP microstrip antenna has been proposed for Beidou navigation system.(2)A novel compact triple-band CP monopole antenna has been proposed for wireless local area network(WLAN)and worldwide interoperability for microwave access(WiMAX)applications.The antenna composes of a square patch etched with an X-shaped slit and a novel improved ground plane.Furthermore,an inverted-L slit is embedded in the radiator to improve the 3-dB axial ratio(AR)bandwidth.Finally,wideband CP antennas are investigated,and three kinds of multiband CP antennas are proposed.(1)A simple monopole antenna with wide circular polarization bandwidth has been proposed for global navigation satellite system(GNSS)applications.The wide impedance bandwidth and broadband CP characteristic are realized based on a simple monopole structure,which consists of a rectangular patch and a novel improved ground plane.(2)A compact monopole antenna with wideband circularly polarization has been proposed for GNSS applications.The key feature of the proposed design is embedding two right-angle isosceles triangular slits and introducing a right-angle isosceles triangular perturbation in the ground plane to improve the CP performance.(3)The design and implementation of a monopole antenna with wideband circularly polarization has been proposed for WLAN/WiMAX applications.The proposed antenna composes of a simple quasi C-shaped patch and an improved ground plane.By appropriately embedding an I-shaped silt in the quasi C-shaped patch and connecting two triangular stubs to the ground plane,broadband impedance is realized,wide 3-dB AR bandwidth is also obtained. |
PDF Full Text Request