| In recent years, with the progress of the combination of multi-mode satellite navigation technology, the design of satellite receiver antenna, which can receive multiple bands signal at the same time has been more and more attention. Nowadays, the global navigation systems include the U.S GPS, Russian GLONASS, the European Union’s Galileo system, leaded by EU GNSS, and China’s Compass(trial run). Microstrip antenna, which was first proposed in1950s, has been to the antenna designers’favorites because of its advantages such as the small size, light weight, low profile, easy to conformal with flying objects and implement the circular polarization and dual-band, multi-frequency operation etc. In such applications, antennas are required with multiple frequency or broadband, circular polarized, low profile, easy to conformal installation. A variety of ways and means to realize microstrip antenna dual-band operation are introduced in this paper. From the patch complexity, it can be divided into single patch and multi-patch. Antenna feeding methods are in terms of coaxial probe, microstrip line feeding, aperture-coupled feeding, CPW, and differential feeding, etc. A lot of methods, like loading technology, gap, slotted, stacked structure and the FSS and others are use in the design of dual-band patch antenna. The achievement of circular polarization includes a single feed, dual-feed and multi-feed and other. Based on the dual-band technology and the circular polarization for a receiver antenna, a small single feed dual-band circularly polarized microstrip antenna is designed. This antenna is operating at Compass B3(1268±10MHz) band and GPS L1frequency band (1575.42±1.023MHz) plus the GLONASS (1574-1610MHz) frequency band. The simulation, analysis and optimization of the antenna were done by the HFSS software.And then, the antenna impedance bandwidth, right-hand circular polarization axis ratio, gain, pattern, and isolation between the two bands were obtained, which meeting the engineering application. This design method is simple in principle, easy to be extended to other band design.In the engineering applications of the microstrip antenna, single antenna sometimes is not meeting certain application requirements, then the array is needed. Microstrip antenna array like other antenna array, can use the array theory to analyze. In a microstrip antenna array, there is the mutual coupling between elements. Mutual coupling has also become an important indicator of a array. A lot of methods were proposed to reduce the mutual coupling. In recently, Such as of the EBG (electromagnetic band gap structure), DGS (detected gap structure) and introduction a coupling unit, or slitting the groundplane of the antenna, to improve the isolation of the elements. Then, a compact five-five element microstrip antenna array is designed, simulated and analyzed. After that, the antenna VSWR, radiation pattern, axial ratio, gain and isolation parameters were given. Because of its poor isolation between elements, a variety of mutual coupling reduction methods were taken and got more than3dB isolation improvement, which can be used in practical application. |
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