Abstract:Because of the specific demand for Beidou navigation system, the system requests the antenna to be, more band, wide beam compact and portable, so that we select the design of broadband rectangular patch microstrip antenna. The paper is combined with micro-strip antenna dual-frequency circular polarization theory with Coaxial feed。The micro-strip antenna is operated simultaneously in the Beidou B2 band (1210 ± 10MHz) and the B3 band (1268 ± 10MHz) by opening the "U" solt on the patch to realize the dual frequency of the microstrip antenna.The design method of this paper is simple and the simulation and parameter optimization of the antenna are carried out by HFSS.The measure results show that its return loss below -20dB; its gain more than 3dB in the bandwidth; the axial ratio of the antenna below 6dB. The results show that the beam has good circular polarization performance,wide beam and the design requirements are achieved. Moreover, the circuit design method is simple, the making process is simple, and this can provide reference for the actual application.