| The research works are presented with scientific projects. The thesis is divided into two parts. First of all, a dual-band high precision positioning satellite user antenna for Beidou Navigation Satellite System (abbreviated as Beidou) and Global Positioning System (abbreviated as GPS) is designed and simulated. The desinged antenna realizes high consistency between the phase center and the geometric center. Secondly, according to the technical requirements, the engineering samples of the wideband circular polarization antenna borne on car which operates from f0±50MHz is proposed and analyzed in detail. The proposed antenna has4%of the oprating bandwidth and realizes the project requirements. The antenna prototype has been delivered to first party to used, and the application effect is good.The main contexts can be illustrated as follows:Firstly, in order to satisfy the project requirements of the high precision satellite user antenna for Beidou and GPS systems, a double-layer microstrip patch antenna is desinged which employs four symmetrical feeding points, a thick medium substrate with low dielectric constant and two feeding networks having two-stage two-way Wilkinson power divider are presented based on the theory of dual-band circularly polarized microstrip antenna. The designed antenna has two frequency bands with its low frequency band cover the B3band of Beidou and high frequency band cover the L1band of GPS and B1band of Beidou. According to the simulation of the proposed antenna, for the required frequency band, the VSWR is less than1.4, the gain at90°in elevation is greater than2.7dB. In the range of90°～24°in elevation, the gain is greater than-5dB, and the antenna pattern roundness is less than1.5dB. The AR is less than6dB, and consistency of the phase center and the geometric center is less than8mm. The front-to-rear is greater than20dB. The simulated results indicate that the designed antenna realizes wide beam coverage on the half-space and relatively high consistency between the phase center and the geometric center.Secondly, the project requirements of the wideband circular polarization antenna borne on car are illustrated. In order to satisfy these requirements, a microstrip patch antenna is proposed based on theories of wideband circularly polarized microstrip antenna, which employs two feeding points, a thick medium substrate with low dielectric constant and a feeding networks having one-stage two-way Wilkinson power divider. On this basic, the prototype of this antenna is fabricated and measured. The measured results of the proposed antenna working from fo±50MHz show a good performance about the project requirements and the testing results are agree well with the simulated results. Accordingly, it has proved the engineering feasibility of design proposal. |
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