The Design And Analysis Of Circular Polarized Large Phased Array At X-band

With the development of the technology of Phased Array, the Phased ArrayAntenna has been widely used in Radar, navigation, electronic warfare and so on.Additionally, circularly polarized (CP) antennas are widely used for their preventionfrom the anti-multipath reflection effects on the propagations of electromagnetic waveand depolarization effects of rain and fog. Nowadays there are three common types ofcircularly polarized antenna to realize the widely scan beam: Microstrip Antenna, CrossDipole and Spiral antenna. The microstrip-antenna is the most widely and popularantenna used by people. This dissertation makes deeply insight to the design of phasedarray（Only taking into account the passive components, not including the active T/Rcomponents） which is consist of the widely scan CP cross dipole and simulation thecharacter of the large array by using the character of small array. The majorcontributions are as follows:(1) A kind of wide beam cross dipole with arm folded down is designed in thepaper. The project is simulated by the software Ansoft HFSS and the results arecalculated by the moment of method (MoM). The element results demonstrate the goodagreement in the simulation and numerical results. Both of their width of main-lobe islarger than100°, and the value of Axial Ratio (AR) is almost lower than4dB.(2)Design an11×11array antenna by using the regular placement. Also simulateand calculate the radiation pattern of array. The results show that the regular placementcould not generate the good CP in the effect of mutual coupling. Compared with theregular placement, we analyse the advantage of the sequential rotation technique. Firstlywe design a2×2sub-array and make a comparison between simulation and theoreticalmethod; then make a deeply research in the12×12array, including theActive-reflection-coefficient and Scan-loss of center elements of the array.(3)Extracting the S parameters of the center element of the12×12manufacturedarray antenna and calculating the Active-reflection-coefficient and Scan-loss, and finallythe comparison results between measured and calculated far-field antenna patterns are given too.(4)Using the MoM simulate the radiation pattern of the large array and analyzingthe large-array radiation pattern by the different method. Finally the results reach therequirement and now the antenna array has been checked and accepted.