Research On Satellite Navigation Multi-channel Receiver

With the development of global integration,satellite navigation systems are used in various fields such as aviation,car navigation,communication,mapping,and entertainment.In order to cope with the rapid development of China's BeiDou navigation satellite system,the academic community has carried out in-depth research on multiplex multi-mode multi-frequency antenna and anti-interference receiver system.This paper studies the satellite navigation antenna-triplexer that can be used in the GPS L1,L5 and Beidou B1 and B3 bands and the four-channel satellite navigation anti-interference receiver RF front-end based on the Beidou B3 band.In this paper,the satellite navigation antenna-triplexer adopts the Substrate integrated waveguide technology and the microstrip slot antenna to design a back-cavity self-triple antenna with three-frequency operation.The antenna consists of two rectangular SIWs.The resonant cavity is composed of three radiating slots and a metal cavity,wherein the smaller sized cavity is nested within the larger cavity.Larger cavities are excited by using two different microstrip feeds,while smaller cavities are excited by coaxial probes.Three different resonances are produced near 1.176 GHz?GPS L5?,1.268 GHz?Beidou B3?and1.57 GHz?GPS L1 and Beidou B1?by using one annular groove and two transverse grooves,respectively.The antenna utilizes three radiating slot configurations.With simultaneous excitation cavity mode(TE₁₁₀/TE₁₂₀)and patch mode(TM₁₀),the average isolation between the three input ports is better than 17dB.The metal back cavity is used to achieve bandwidth expansion,and the bandwidth of the SIW microstrip slot antenna of the single layer medium is increased from 1%to 4%.Compared with the traditional antenna-triplexer,the antenna structure designed in this paper is easier to implement in a compact space.In order to verify the proposed design,the test results are consistent with the simulation results.In addition,the forward-backward suppression ratio at the antenna resonance point is better than 14.5dB,and the measured gain values of the GPS L1,L5,and Beidou B1 and B3 frequency points are 9.03,5.75,8.56,and 7 dBi,respectively,and the visual axis direction at the corresponding frequency point.The cross polarization levels are greater than 22.1dB,31dB,25.3dB,and 25.5dB,respectively.The proposed design is compact,easy to manufacture,and can be integrated with planar circuits.In this paper,the Beidou B3 band anti-interference receiver four-channel RF front-end adopts super-heterodyne receiver topology,featuring high sensitivity and large dynamic range.In order to reduce the system noise figure,the signal received by the antenna is first subjected to low noise processing.Considering the signal interference,the designed link gain is 50⁶6dB.The RF front end uses a modular design to simplify the process and is divided into RF modules,mixers,IF modules,frequency source modules,and power modules.Simulation of the system link determines that the performance of the system link parameters meets the requirements.The system operating voltage is 5.0V and the operating current is1.3A.The test can obtain a link gain of approximately 64 dB,a four-channel gain difference of less than 1 dB,and good amplitude uniformity.The phase noise is about-88dBc/Hz@100KHz,the gain flatness is within 3dB,the noise figure is 1.5dB,and the performance parameters of the four channels are consistent,all satisfying the anti-interference receiver.RF front-end performance specifications are required for anti-jamming receiver systems.