Research On CP Mircrostripantenna With Wide Beamwidth Andarrayantenna For GPS Band Application

With the development of satellite navigation, positioning and communication system, there are ever-increasing demands on the coverage of the antenna. In order to get the weak satellite signals quickly, it generally requires the antenna has a broad beamwidth and maintains a certain low elevation gain. In certain applications ,such as the GPS ,the desired antenna unit should have the 3dB beamwidth of 120°or even higher, and the broadband with good circularly polarized characteristics. GPS satellite signal power is very low, highly vulnerable to be interfered by various types of radio frequency (RF). Both for the unintentional interference or jamming, GPS is very sensitive, which makes the accuracy of GPS have become a precision under certain conditions. It becomes an urgent important issues that how to enhance the GPS anti-jamming capability. Among the many anti-jamming technology, the adaptive antenna technology is more potential. However, when the antenna is non-ideal state, it will make the adaptive algorithm performance declined significantly, or even failure. For the above, we conducted a detail research on CP mircrostrip antenna unit with wide beamwidth for GPS band application, and the design for array antenna in case of mutual coupling. Following major elements:Microstrip antenna is widely used in many practical applications, because of its thin profile, small size, light weight, easy to obtain circular polarization, and easy to make and the conformal structure of the satellite carrier surface, etc. Firstly, according to the demand of GPS antenna for wide beamwith and circularly polarized characteristics, we have designed the CP microstrip antenna with wide beamwidth for GPS band application, and it has a larger beam width and better circular polarization characteristics. Design presents a simple way to broaden beamwidth of the microstrip antenna. In the structure, the slotted ground plane antenna mounted on the three-dimensional pyramidal structure of conductor walls, because of the reflection of the pyramidal structure of conductor wall, the antenna can get wider beamwidth, as well as increase the F/B Ratio. There is less research on the method of the three-dimensional ground plane structure. Compared with the antenna which has the similar structure, it has many advantages ,for example ,its ground structure is simple, it is smaller ,it has higher gain, and it is easy to implement, the beamwidth, axial ratio bandwidth of the antenna are able to meet the need of the CP microstrip antenna with wide beamwidth for GPS band application.Secondly, mutual coupling is one of the important features inherent in the antenna array, which will be the main factor to design the array antenna. As a result of the adaptive antenna array as a receiver, so it inevitably involves the issues of mutual coupling for the design and applications. Antenna array mutual coupling not only have an impact on the gain, beam width and other electrical parameters to a certain extent, but also will change the received signal amplitude and phase of the array. Research on the antenna array mutual coupling effect is highly significant to improve the performance of the array antenna reception. Finally, according to the analysis and comparison of coupling effects on the different lineup, we designed the 4 units circularly polarized microstrip antenna array for GPS band application by the sequential rotation method, on the basis of reasonable lineup to decrease mutual coupling.