Research On Navigation Antenna Based On Fractal And Periodic Structure

With the development of science and technology,including military,commercial and civil fields are more and more dependent on satellite navigation systems.The antenna is responsible for signal reception and transmission in satellite navigation systems,and the antenna performance is determined by the structure of the antenna.So the design of satellite navigation antenna is particularly important.In this paper,the basic theory of microstrip antenna and fractal is introduced.Three different satellite navigation antennas with different structures are designed,which are based on the theoretical knowledge mentioned above.The designed antennas were modeled and simulated by the high-frequency electromagnetic simulation software Ansoft HFSS 15,and all of them were fabricated.The performance of the antennas were measured in the anechoic chamber environment.Finally,the simulation results are compared with the measured results.There is not much difference between the two results.In addition,the parameters and structure of each antenna were analyzed using the parameter optimization function in HFSS,and the effect on the performance of the antennas were directly demonstrated.The first antenna is improved on the Sierpinski fractal,and a novel hexagonal fractal structure is proposed,and the miniaturization of the antenna is achieved by the fan-blade shaped structure.The impedance bandwidth of the antenna is 4.4%,which can be covered in the GPS L1 band,and the gain is 2.02dB.The second antenna applied the hybrid fractal structure and loaded with the periodic structure in order to achieved the circular polarization of the antenna much better.The hybrid fractal structure improves the gain of the antenna,which is 4.24 dB at the zenith direction.The third antenna applied three-dimensional fractal structure.All aspects of its performance are better than the two antennas designed before.The gain and the 3-dB ratio bandwidth of the antenna are 5.93dB and 36.5%,respectively.The dual frequency operation was achieved,and the two resonant frequencies are 1.227GHz and 1.575GHz.The antenna can work stably in the L1,L2 bands of GPS and the B1 band of BDS.