Research On Car Borne Antenna For Compass Satellite Navigation System

Normally, the maximize gain of the patch antennas, which have the advantage of small size and easy to fabricate and simple structure, is occurred at the patch vertex, such as the antenna used in the Isatphone can be aimed the handset to the satellite. The first generation Compass Satellite Navigation System of China fixed in geosynchronous orbit which is right above the equator, the satellite's location is not in the zeith position. For domestic users, specailly users of high latitudes, since the navigation satellites located in very high position, in order to ensure the reception, the maximize gain of the antenna must directed towards satellite's location.Our research work has been divided into four parts, that is (1) to design and manufactured a conical spiral antenna for the Compass system; (2) to minimize the conical spiral antenna; (3) to design a pair of quadrifillar helix antennas for the Compass system, and (4) to minimize the quadrifillar helix antenna by using meander line technique.Firstly, we have analyzed, which based on the theory of the frequency-independent antenna and a lot of simulation results, the configuration, the design graph and the properties of the conical spiral antenna, we have designed and fabricated a conical spiral antenna (CSA) for the Compass system to receive timing signal. While the maximize gain of this CSA aim to the obit of satellite, which improves the capability of intercepting the navigation signal. The CSA has been measured in microwave chamber. At same time, the CSA has minimized to reduce the height of the antenna, and finally obtained more than 50% height reduction.The last part of the thesis is concentrated to analyze and design a pair of quadrifillar helix antennas for the car borne system, the antenna system has both charactertics of the transmitting and the receiving. This antenna can work in L-band transmitting with the left-hand circular polarization (LHCP) and S-band receiving with the right-hand circular polarization (RHCP), and has great advantages in the low elevation performance and the axis ratio with a prospect of practical using. Considering to miniaturization of the antenna, moreover, through lots of the optimization designs and simulations, we use the meander line technique to minimize the height of the quadrifillar helix antenna, and the height finally has been reduced by 67% and the bandwidth has been extended evidently.