Research Of 5G Millimeter-Wave Antenna And Array Based On Characteristic Mode Analysis

With the continuous development of information transmission technology,the fifth generation of mobile communication(5G)has gained widespread attention.In particular,the communication rates in the millimetre wave band meet the requirements for higher bandwidth,lower latency,higher transmission rates and lighter electronic designs,and high performance antennas covering specific millimetre wave operating bands are in urgent demand.However,the diversity and complexity of application scenarios make the analysis and design of patch antennas increasingly difficult.Fortunately,the recent development of Characteristic Mode Analysis(CMA)has become a powerful tool for solving complex electromagnetic radiation problems;CMA can determine the resonant frequency band and radiation direction map of an antenna based on shape and other characteristics alone,without adding additional complex feed structures,providing a clear physical explanation for antenna design.This thesis implements the analysis and design of an antenna array operating in the 5G millimetre wave band based on the CMA technique,as follows:(1)A 5G dual-band millimeter-wave microstrip antenna array is proposed based on CMA.By analyzing the characteristics such as mode current and mode direction map,the circular antenna unit is adjusted to an open-slit dual-band structure and the resonant modes are optimized for frequencies of 28.0 GHz and 38.0 GHz.Based on the mode current distribution,a substrate integrated waveguide(SIW)slot is used to excite the selected eigenmode to achieve multimode resonance,thus obtaining dual-band characteristics.Finally,to improve the gain and directionality of the antenna,a 1×4linear antenna array is designed using the SIW in combination with the antenna unit.Simulation results show that the impedance bandwidth of the array is 27.5-29.4GHz and 36.2-40.2GHz with peak gains of 13.0d Bi and 11.4d Bi respectively.(2)A CMA-based broadband circularly polarized magnetoelectric dipole(MED)antenna array is proposed.The parameters such as mode validity and eigenangle of the antenna unit are first analyzed using eigenmode theory,and the potential properties of broadband and circular polarization are found,using SIW to excite the eigenmode of the MED.Then the SIW sequential rotating phase feed structure was designed to implement a 2×2 antenna array,further improving the axial ratio bandwidth and gain.Test results showed that the antenna array had an impedance bandwidth of 40.3%(25.05-37.14GHz),an axial ratio bandwidth of 31.3%(23.14-32.54GHz)and a peak gain of 14.3d Bi.(3)A high-gain U-shaped millimetre wave super-surface(Metasurface,MTS)lens antenna array is proposed based on CMA.the CMA of the U-shaped unit shows two available eigenmodes in the 28 GHz band,which are excited with a certain phase difference,reducing the electromagnetic wave reflection.The lens unit has a transmittance greater than 0.8 in the operating band and a phase coverage of 360°.Based on this unit,a transmission array was first designed based on the phase distribution of the focused lens array,with a total lens size of 92.4 x 92.4 mm2 consisting of 21 x 21 units,a focal diameter ratio of 0.85 and a horn antenna as the feed source.The results show a peak gain of 26.7 d Bi at 28 GHz,a gain bandwidth of 5.8%at 3 d B and a radiation efficiency of 81.6%.Beam formation in eight different directions was then achieved by using multiple horn antennas as feed sources.Finally an MTS lens with a beam deflection of 30° was designed.The thesis has 82 pictures,7 tables and 86 references.