| With the comprehensive popularization of the fourth generation(4G)mobile communication system and the accelerated promotion of the fifth generation(5G)mobile communication system,the communication system puts forward higher and higher design requirements for the antenna.The antenna is the bridge betweep the mobile communication system and the mobile users,and also the entrance and exit of information.Its performance plays an important role in the overall performance of the mobile communication system.5G as the latest generation of mobile communication technology,compared with 4G communication technology,has the advantages of faster data transmission speed and higher signal quality.In order to meet the growing demand of 5G communication system for data rate,and to be compatible with 2G,3G and 4G communication systems which are still widely used,this paper studies the broadband multiple input multiple output(MIMO)base station antenna and mobile terminal MIMO antenna,and achieves the following results:(1)A new broadband MIMO antenna unit for 4G/5G communication system is proposed.The antenna unit is composed of two heart-shaped dipole distributed on both sides of the dielectric substrate symmetrically placed at an angle of ±45°.The measured results show that the reflection coefficient of the antenna is less than-14dB and the isolation degree is greater than 27dB in the frequency band of 2.3-3.6GHz.The radiation is ±45° dual-polarized wave,the gain is about 7dBi,and there is a stable radiation pattern.(2)A broadband MIMO base station antenna for 4G/5G communication system is designed.In order to meet the requirements of the base station antenna and improve the antenna gain,the designed broadband MIMO antenna element is used as the array element to form an eight-element linear array.A feed network is designed for the array by cascading seven bisector Wilkinson power dividers.The measured results show that the working frequency range of the antenna array is 2.3-3.6GHz,the isolation between ±45° polarization input ports is greater than 28dB,and the gain is about 12dBi.(3)A small indoor base station MIMO antenna with stereo coverage is designed.The antenna consists of seven broadband MIMO antenna units.A kind of one sixth bisection broadband power divider is designed,which is used as the feed network of a horizontal six prism ring antenna array.Two 50Ω coaxial lines are used to feed the two polarized ports directly to the antenna element radiated in the vertical direction.The measured results show that the reflection coefficient of the antenna is less than-14dB and the isolation degree is more than 26dB in the frequency band of 2.3-3.6GHz.The antenna radiates dual polarization waves in all directions of the horizontal plane and vertical down direction,and achieves the goal of hemispherical stereo coverage.(4)A mobile terminal MIMO antenna is designed,which consists of two 2G/3G/4G antenna units and four 5G antenna units.The test results show that the reflection coefficient of 2G/3G/4G antenna unit is less than-6dB and the isolation degree is more than 15dB in the frequency bands of 817-975MHz and 1656-2730MHz;the reflection coefficient of 5G antenna unit is less than-10dB and the isolation degree is more than 17dB in the frequency bands of 3400-3600MHz and 4800-4900MHz;the antenna can be used in 2G/3G/4G and 5G mobile communication. |
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