Koch分形在圆极化微带天线中的应用

Apply the Koch Fractal to the Circularly Polarized Microstrip Antenna

馈电,从而实现微带天线的圆极化特性。采用电磁仿真软件CST Microwave Studio对天线进行了设计,得到了可以工作于GPS系统1228MHz频段的一次和二次分形的圆极化微带天线结构参数。根据设计结果制作了天线样机,并在微波暗室内进行测试,结果表明一次分形和二次分形天线均谐振于1228MHz,相对阻抗带宽、轴比及增益分别为1.5%和1.4%、2.5dB和1.4dB、2.7dB和2.4dB。二次分形天线与一次分形天线相比,轴比特性有明显改善。

Apply the fractal method to the design of the microstrip antenna.These kinds of square microstrip patches have Koch fractal boundary structures whilst probe feed on the diagonal line properly,thereby achieving the circularly polarized character.The antennas were designed on the software CST Microwave Studio,then they obtained the circularly polarized microstrip antenna structural parameters of once and quadratic fractal which made them working in the GPS system at 1 228 MHz frequency band.According to this simulating,the prototypes were made and tested in the anechoic chamber.And the result illustrated the data of the impedance bandwidth,the axial ratio and the gain of once and quadratic fractal antennas（syntonying at 1 228 MHz）,respectively.Specifically,they were 1.5% and 1.4%,2.5 dB and 1.4 dB,2.7 dB and 2.4 dB.Comparing with the once fractal antenna,the axial ratio of the quadratic fractal antenna is obviously better.