| With the continuous development and innovation of mobile communication technology,the era of 5G communication is getting closer and closer to us.One of the main differences between 5G communication systems and 4G systems is the shift to the millimeter wave band.The US Federal Communications Commission has designated the 27.5 to 28.35 GHz band for 5G applications,which makes it easier to achieve wider bandwidth and achieve the expected high data rates and system capacity.With the continuous development of 5G communication systems,intelligent communication devices are also constantly innovating,especially mobile phones and smart wearable devices.The evolution technology of 5G mobile terminals poses a huge challenge for its antenna system.As a vital part of intelligent communication devices,antennas directly affect the overall performance of intelligent communication devices.Based on the research of 5G communication system and many antenna types,this thesis proposes three antennas that can be used in future 5G communication systems,and each antenna has different design methods,unique advantages and application environments.This paper first expounds the background and significance of this research,and introduces the development history and research status of mobile antennas.Then briefly introduce the basic definition of the antenna and some antenna parameters and explain the basic theory of phased array antenna,microstrip patch antenna and circularly polarized antenna.Finally,three different types of antenna designs are proposed based on the theoretical basis and the 5G frequency band.1.A phased array antenna composed of an antenna element with a Bow-tie structure is designed.The antenna element is designed with two identical irregular hexagonal patch structures on two different faces of the dielectric substrate.The antenna element has a-1OdB bandwidth of 10.1 GHz,covering the 24.1GHz to 34.2GHz frequency band,with a center frequency of 28.1GHz and a gain of about 4dBi.The working frequency band of the antenna array is 26 GHz to 37 GHz,the gain is greater than 12dBi,the spacing of the antenna elements is determined to be 5.5 mm(about 0.53 λ),the isolation between elements is greater than 16 dB,and the beam steering characteristics are good.The antenna was fabricated and tested according to the simulation model.2.A microstrip patch antenna with DGS structure is designed.The antenna element changes the conventional microstrip patch antenna to an inverted "凸" structure,and designs an inverted "凸" DGS structure.The antenna element has a simple structure and a wide bandwidth.The-1OdB impedance bandwidth is 5.1GHz,covering the 25.5GHz～30.6GHz frequency band,the center frequency is 28GHz,and the gain is about 6.3dBi.The working frequency band of the antenna array is 26 GHz to 30.5 GHz.The array antenna has a strong directional beam with a gain greater than 16dBi,the antenna element spacing is determined to be 9.5 mm(about 0.89λ),and the isolation between elements is greater than 25dB.The antenna was fabricated and tested according to the simulation model.3.An OCP antenna based on the theory of magnetic dipole antenna is designed.The antenna element consists of a"卍" or"卐" shaped copper patch on the top of the antenna substrate and a reverse copper patch on the bottom,and the top and bottom copper patches are connected through the substrate through copper plated through holes.The antenna element has a-10dB impedance bandwidth of 1.5GHz,covering the 23.3GHz～28.8GHz band.The 3dB axial ratio bandwidth is 2.6GHz,covering the 26.2GHz～28.8GHz band.The center frequency is 28GHz and the gain is around 2.2dBi.The physical object of the antenna element was fabricated and tested,and the test results were basically consistent with the simulation results.The proposed 2×2 antenna array has a working frequency range of 27.3 GHz to 28.6 GHz.The gain in the working frequency band is above 3.5dBi,the antenna element spacing is determined to be 4.58 mm(about 0.43 X),and the isolation between elements is greater than 13dB.The proposed eight-element antenna array has a working frequency range of 27 GHz to 28.5 GHz,a gain of more than 12dBi in the operating frequency band,an antenna element spacing of 5.28 mm(about 0.5 λ),and an isolation between elements of more than 10dB. |
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