The Design Of Microstrip Antenna For Satellite Navigation System

Since the mid1970s, the theory of microstrip antenna has great development. Because themicrostrip antennas have the characteristics of compact structure, small volume, light weight, lowprofile, easy to manufacture and so on, they get the favor of people. Moreover, circularly polarizedmicrostrip antennas synthesize many advantages of microstrip antennas. Circularly polarized waveitself has some characteristics such as restraining the interference of mist, fighting multipathreflections, having better mobility and so on. So circularly polarized microstrip antennas are widelyused in radar, navigation, satellite system and so on. Satellite navigation system has made greatcontribution to communications, military, transportation, radio, entertainment industry. So it is verynecessary to study the satellite navigation.As the important component of the satellite navigation system、the antenna’s performancedirectly influents the performance and sensitivity of the receiver. So People have the higher requestto the antenna performance.In a variety of applications of satellite navigation,we not only ensureaccuracy,but also we hope the equipment is small and light.So small size of equipment is extremelyimportant.In future,Chinese satellite system should have smaller size and high levels of integration.This paper synthesizes the basic theory and electromagnetic simulation software-HFSS.Acircularly polarized microstrip antenna for satellite navigation system is designed, whose workingband is24915MHz. Its polarization way is a right-handed polarization. The antenna is designedwith four slots equally spaced. By adjusting the slots’ length and choosing appropriate feed position,circularly polarized radiation of microstrip antenna can be achieved. For the design of a single-feedcircularly polarized microstrip antenna, the two required orthogonal modes with equal amplitudeand900phase difference can be excited by truncated patch corners and slots.So the circularpolarization can be obtained. By truncating corners and cutting circular slot in the center of patch,the size of antenna is lowed. Its principle is that the slots on the patch or changing the shape of thepatch can introduce the perturbation to make the surface current twist.Then the current’s effectivepath will get longer,and the resonant frequence is reduced.In guaranteeing the actual size of raditionpatch under a constant,the effective length of the patch is increased.So,in case of a fixedfrequence,the size of the antenna is reduced.The biggest feature of this antenna in this paper is thatcompared with the same dielectric substrate, the antenna’s size decreases by15%.In the sametime,the antenna has a gain of3.4dB and a good bandwidth.This antenna take a good compromisebetween decreasing the size of antenna and having a good gain.In addition,the antenna achieves agood circular polarized radition. This paper uses a new designing method, which is designing the feed network of the arraylonely. That is to say, the feed network separates from the array of antenna.This method not onlycan reduce the size of the array of antenna, but also reduce the coupling between the antenna andthe feed network. By using the ADS and HFSS for the simultaneous simulation, a power Wilkinsondivider is designed.The simulation results show that the power divider has small reflection、smallinsertion、ahigher isolation. So the power divider fully complies with the requirements of designing.In addition, a14linear array and a22face array are designed.Using the electromagneticsimulation software HFSS, we compare the two different structures of array, by the indexes of size,axial ratio, gain and so on. Finally a face array which has compact structure is selected.At last，22face array is manufactured and tested.