Research On Low Noise Amplifier Applied To The Front End Of Beidou Navigation Antenna

This thesis mainly introduces the design of low noise amplifier and microstrip antenna used in the BeiDou Satellite Navigation System, and the preliminary research on active antenna based on the low noise amplifier. This thesis studies the low noise amplifier based on the low noise transistor and integrated chip, designs the bias circuit and matching circuit, and realizes the index requirements of low power consumption, low noise and high gain. The thesis also designs a microstrip antenna applied to the BeiDou Satellite Navigation System. The antenna performs well in the vertical direction and the low elevation. The thesis completes the simulation and test of the active antenna based on the low noise amplifier.This thesis firstly elaborates the related theory of the low noise amplifier, such as the theory of two-port network and matching network, the transmission line theory. This thesis designs a two-stage low noise amplifier according to the index requirements operates at the band of B3(1268MHz±10MHz) with low current and high gain. The first stage is an E-PHEMT low noise transistor with good noise performance and small bias current. The second stage is an integrated low noise amplifier chip with high gain and small bias current. The thesis uses LC components to design the matching network. The source negative feedback of the transistor can enhance the stability of the amplifier and adjust the voltage standing wave ratio and noise figure. The feasibility of the PCB work at radio frequency is validated through the co-simulation of the schematic and layout circuit. This thesis also designs a two-stage low noise amplifier based on MMIC. It operates at the L band. The matching network is designed by LC components. The low noise amplifier achieves higher gain and low current when satisfy the requirement of noise figure at the same time. It finally covers multiple frequencies commonly used in L-band.This thesis secondly designed a right-hand circular polarized microstrip antenna applied to the BeiDou Satellite Navigation System. The working frequency is the B3 band(1268MHz±10MHz) of BeiDou. The right-hand circular polarized of the antenna is realized through dual-feed by the 3dB branch line coupler. The design improves the performance of the axial ratio and impedance by introducing metal hole in the radiation patch. Finally we achieved a right-hand circular polarized microstrip antenna with good performance of low elevation. Then the design is about the active antenna based on the low noise amplifier. This thesis firstly designs a single-stage low noise amplifier operates at B3 band. Then integrate with the antenna. And test the receiving performance.