| The research works are discussed with scientific projects. The thesis is divided into two parts. A quad-band antenna with common aperture is simulated and measured in the first part, the measured results show that the proposed antenna realizes the technical requirements. Then the prototype of dual-band dual-sense circularly polarized(CP) antenna is introduced,which achieves the technical parameters and has the good application effect.The main contexts of the thesis are as follows:1. According to the project requirements of the common aperture antenna, the development history, current state of the art and technical difficulties are introduced. The technology and method of microstrip antenna miniaturization and multi-frequency are proposed. Multilayer microstrip antenna which employs a thick medium substrate with high dielectric constant is designed based on the theory of microstrip antenna. The proposed antenna works in UHF-band and S-band, respectively, and 2×2 array is employed in S-band to achieve beam scanning. According to the simulation of the proposed antenna, for the required frequency band, the voltage standing wave ratio(VSWR) is less than 1.5, and the gain at ±60°in elevation is greater than-2d Bic in the UHF/S bands.. On this basic, the prototype of this antenna is fabricated and measured. The measured results show good agreement with the simulated results which meets the project requirements. Accordingly, it has proved the engineering feasibility of design proposal.2. According to the project requirements of dual-band dual-sense circularly polarized antenna, some difficulties in achieving high performance on dual-band dual-sense CP antenna are pointed out. On the basis of comparative analysis on dual-sense CP antenna, Planar printed antenna is employed to achieve performance. According to the simulation of the proposed antenna, the VSWR is less than 2 in the dual-band, and the dual band circular polarization with left hand circular polarization(LHCP) in the lower band and the right hand circular polarization(RHCP) in the upper band are obtained. The proposed antenna is fabricated and simulated, the measured results show good agreement with the simulated results. Therefore, it can be proved that this designmethod is effective for application in engineering. |
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