| The research works are made with scientific projects. The main research works can be divided into two parts: A dual-band four-frequency in one aperture for airborne antenna is proposed in the first part, the simulated and measured results show that the proposed antenna realizes the technical requirements. The engineering prototype is applied. Then the triple-band miniaturized antenna for handsets is introduced and fabricated in the second part, which meets the performance requirements.The main contexts of the thesis are as follows:Firstly, according to the project technical requirements of dual-band four-frequency airborne antenna in one aperture, the concepts, application, development history and current situation of the antenna are introduced. The design difficulties is how to achieve dual-band, four-frequency, common aperture, airborne and wide beam pattern, circular polarized(CP). Then the design methods of multi frequency and circular polarized are discussed. Lamination technology is employed to realized the common aperture. By using a phase shift network and a double-fed method, the proposed antenna can exhibit wide beam circularly polarized radiations, and four units are fed respectively in S-band to realized beam scanning in ±60°. The software ANSYS HFSS is used to design and simulate the presented antenna. The experiment results show that the voltage standing wave ratio(VSWR) is less than 2 at quad operating bands and the gains of the antenna are greater than-2.5d Bic in the UHF band and-1.0d Bic in the S band within the directions of ±60°.The axial ratio(AR) values are less than 6d B over the whole operating bands. The proposed antenna is fabricated and measured based on the simulated design. The measured results achieve the features of wide beam and circularly polarized in the dual-band quad-frequency antenna with common aperture, which verifies the proposed design process.Secondly, according to project requirements, a triple-band miniaturized antenna for handsets is proposed. The development history and current situation of positioning handheld terminal antenna for COMPASS are elaborated. The difficulties in achieving antenna performance are pointed out such as miniaturization, wide beam and high-performance. The performance of the proposed antenna is simulated and optimized by the ANSYS HFSS. On the basis of simulated results, a prototype is fabricated and measured. According to the measured results, the VSWR is less than 2 in the operating bands, circularly polarized and wide beam are achieved in the triple-band. Therefore, it can be proved that this design method is effective for application and engineering. |
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