Research On Ultra-wideband And Circularly Polarized Microstrip Antenna

With the increasing demand for the performances of the antenna, microstrip antenna with ultra-wideband (UWB) or circular polarization (CP) has became the hotspot. In this paper, the investigations on the technology of UWB and CP microstrip antenna has been set in the background of WLAN/WiMAX/UWB and Beidou Radio Determination Satellite Service (RDSS). Four types of UWB microstrip antenna and two types of CP antenna have been proposed and manufactured. The measured results closely meet with the simulations.The research contents are as followings:An E-Shape UWB patch antenna and C-Shape loaded UWB slot patch antenna was designed for Short Range Wireless Applications. The former has a bandwidth from 5.15GHz to 5.825GHz while latter cover two bandwidths of 802.11a/WiMAX. For the E-Shape antenna, the principles of achieving broadband are analyzed via its equivalent circuit model. And the influence of the size parameters of the C-Shape antenna on its performances has been studied. Both of the two antennas have been manufactured and the measured results meet closely with the simulations.Two types of band-notched printed monopole antennas are proposed for the applications of UWB system. Both of them covered the UWB bandwidths from 3.1GHz to 10.6GHz. They are respectively single band-notched for 802.11a and dual band-notched for 802.11a/802.11b to avoid bothering existed system. The band-notched mechanism and the influence of antennas size parameters are discussed. Material objects are made out and the measured results agreed with the requirements for the UWB applications.A type of CP antenna using for Beidou RDSS system combining reception and transmission is proposed. The size of the antenna decreased as sharing caliber design is adopted and the 3dB axial ratio bandwidths reaches 15MHz and 10MHz respectively for the two bands. It meets the needs of the requirement. A type of coplanar waveguide-fed broadband CP slot antenna of which the 3dB axial ratio bandwidth reaches 16.1% was developed. Its performance is much better than the regular coaxial-fed or microstrip-fed CP antenna.