| Since the 20th century,90 years, Global Satellite Navigation System with its fast, high efficiency and high accuracy measurement, is by various industry data collection and resource monitoring officers of all ages. In recent years, Countries in the world, Regions and Organizations have to develop their own Satellite Navigation System. Addition to the U.S. GPS and Russian GLONASS, the China Compass navigation and the EU Galileo project are also developing rapidly. Multi-mode cooperation will be the trend for satellite navigation system in future.Although the signal processing technology is well established, Multi-path is a prime source of navigation errors in GNSS-based navigation systems. Multi-path errors arise from interference between the received direct and reflected signals from the low elevation and negative elevation in the receiver. In order to suppress multipath interference, the navigation receiver antenna should be small radiation properties at low elevations and good cross-polarization radiation. And it is't a good method to enlarge the ground of antenna to improve the radiation properties, as to Small size, light weight. So some techniques of inhibition of surface wave has been proposed.This article describes Choke-Ring Antenna and Shorted Annular Patch Antenna. Shorted Annular Patch Antenna is a good choice for satellite navigation system, because it has some principal advantages, such as small size, light weight, low profile and so on. And the key points in this paper is the studies of the technologies of the broadband microstrip antennas and circularly polarized antenna. It comprises a stacked Shorted Annular Patch antenna and utilizing the proximity coupling balance-feed with four-arm inverted L-strip, the impedance bandwidth and circularly polarized bandwidth can be effectively enhanced, and cover GPS, GALILEO, GLONASS, COMPASS that the impedance bandwidth is up to 40% for VSWR< 2(1100MHz～1620MHz). With the Phase-shifting network of broadband power divider and four-feed by a difference phase of 0°,90°,180°,270°The 3dB axial ratio bandwidth is up to 45%. A peak gain of around 4.5dB is obtained in the entire bandwidth. It meets the demands of the multi-mode airborne satellite navigation system.In order to improve the performance of the antenna, a broadband low noise amplifier (LNA) is designed in this paper. With the Feedback and dual-stage amplifier, the gain of amplifier is greater than 28dB,±1dB of gain flatness,and noise Fig.ure less than 2. |
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