Design Of Miniaturized Antenna For Application Of Internet Of Things

With the rapid development of Internet of Things technology and communication technology,people's demand towards wireless communication terminals is increasing.Traditional SISO antenna can no longer meet data transmission requirements of 4G/5G eras due to its shortcomings.MIMO technology,as one of the core technologies of current communication,can make up for these shortcomings.MIMO technology can improve transmission rate,increase system capacity,and reduce the bit error rate by adjusting the number of antenna under the premise of not increasing transmit power and working bandwidth.Meanwhile,the miniaturization trend of mobile terminal also increases the difficulty of MIMO antenna design,and the coupling between antenna elements of same frequency band is a major obstacle.In view of the above problems,this thesis proposes three MIMO antenna systems in miniaturized mobile devices.The main work includes:1.A four-element MIMO handheld terminal antenna operating at high frequency WIFI(5.15GHz-5.85 GHz)is proposed,which consists of three identical dipole antennas and one slot antenna.The measured results show that the return loss of all four units is below-10 dB and the isolation is lower than-20 dB.The radiation efficiency is higher than 70%,and the highest is 87%;the gain is above 2.8dBi and the highest is 4.5dBi.2.An eight-element MIMO handheld antenna for 5G(3.4GHz-3.8GHz,5.15GHz-5.925GHz)is proposed.Each antenna is made up of a radiation patch protruding from feed point and a short-circuited stub protruding from ground.The measured results show that the return loss of eight units is below-6dB.The high-frequency unit isolation is below-22 dB,and the low-frequency unit isolation is below-14 dB.The radiation efficiency of all units is higher than 50%,and the far field gain is greater than 2.8dBi.3.A 12-cell MIMO handheld terminal antenna for 5G(3.4GHz-3.8GHz,5.15GHz-5.925GHz)is proposed.The high-frequency unit adopts slot antenna and the low frequency unit adopts monopole.The measured results show that the return loss of all units is lower than-6dB.Isolation between all antennas is lower than-14 dB.The radiation efficiency of the high frequency unit is higher than 50%and the radiation efficiency of the low frequency unit is higher than 40%.The far field gain of all units is greater than 2.2 dBi.