Design And Research Of Planar Antenna For Satellite Communication

SATCOM-ON-THE-MOVE(SOTM)is short for mobile satellite ground station in the communication system.Vehicles,ships,airplanes and other mobile vehicles can track the target satellite in real time during the movement with SOTM,and continuously transmit multimedia information such as voice,data,and images.As a commonly used antenna type in the SOTM antenna,the planar antenna has the advantages of high mechanical strength,high efficiency and small volume.In the current field of satellite communication,the planar antenna has also become a popular research direction.Based on the research of the planar antenna,this paper designs three planar antennas suitable for different frequency bands and different polarizations,and also gives the analysis and discussion of simulated or measured results.The main research contents of this paper are as follows:1.A Ku dual-band dual linear polarization planar antenna is designed in this paper.The basic radiation unit of the antenna is a square waveguide horn loaded with a metal cross grid,because the horn antenna has the advantages of simple structure,wide frequency band and large power capacity.The feeding port of the horn is connected to the total port of the OrthoMode Transducer(OMT),and the coupling and the pass-through port of the OMT are respectively connected to the upper and lower power dividers to realize the feeding of two orthogonal linear polarizations.Then,the high and low frequency filters are respectively connected to the total port of the upper and lower power dividers to realize the isolation of the antenna for transmitting and receiving.Finally,from the simulation results,it can be seen that the antenna can work in the wide frequency band of 10.75GHz-14.5GHz,the relative bandwidth is 29%,the port isolation is greater than 90 d B,and the radiation efficiency of the whole frequency band is greater than 85%.2.In recent years,Ka-band satellite communication systems have attracted increasing attention and Ka-band antennas mostly use circular polarization to resist the influence of rain attenuation.This paper achieved a Ku-band circularly polarized planar antenna based on the sequential rotation feeding method,which lays a certain foundation for the subsequent research on Ka-band circularly polarized antennas.The basic unit of the antenna is a chamfered square waveguide horn,but the axial ratio bandwidth of the chamfered horn is far from the design requirements,so the sequential rotation feeding method is chosen to widen its circular polarization bandwidth.The feeding network adopts the single-layer parallel feeding,which is composed of two-stage power dividers.After many simulations and verifications,the feeding phase of the first stage 1:4 power divider is selected as0°,90°,0°,90°,and the second stage is 0°,90°,180°,270°.Finally,from the simulation results,it can be seen that the feeder network works well,the axial ratio bandwidth of antenna is broadened from 4% to 19%,while the VSWR in the working frequency band is less than 1.3.Meanwhile,the measured results show that the VSWR is less than 1.5 and the axial ratio is less than 6d B in the working frequency band.3.In a two-way satellite communication system,the downlink and uplink usually operate in different frequency bands.A K/Ka-band shared aperture dual-frequency bands single linearly polarized planar antenna is designed in this paper,and considering the need for circular polarization,a Polarization Converter Metasurface(PCM)is loaded on the antenna to make it work as dual-frequency dual-circular polarization.The antenna unit is a dualmode circular waveguide resonator,which generates TM010 modes at high and low frequencies respectively.The resonant cavity is fed by opening resonant windows at the broad sides of the rectangular waveguide.A duplexer is added at the total port of the feed network to realize the isolation of transmitting and receiving.Then,a PCM is added above the antenna with a certain distance to realize the conversion from dual-frequency single linear polarization to dual-frequency dual circular polarization.Finally,it can be seen from the simulation results that the antenna radiates LHCP and RHCP waves at high and low frequencies,respectively.Meanwhile the low-frequency and high-frequency axial ratio bandwidth is 6% and 7%,respectively.Secondly,due to the particularity of the antenna unit,the profile of the dual circularly polarized antenna array is only 2.3λ20GHz,which is an ultralow profile among similar products.