| In recent years,with the rapid development of wireless communication industry,the fifthgeneration mobile communication technology(5G)has been popularized.With the surge of communication traffic and the rapid growth of user devices,the application demand of 5G millimeter wave band is gradually increasing.Considering that the millimeter wave band will bring greater communication bandwidth and millisecond delay,the millimeter wave communication technology in China has started a lot of basic pre-research.Based on this background,this paper studies a variety of 5G millimeter wave communication antennas suitable for mobile terminals and analyzes their characteristics,mainly focusing on the design and research of millimeter wave miniaturized array and wide-angle scanning array with wide-band coverage.1.A dual-band and dual-polarized millimeter-wave antenna array is proposed.(a)Dual-band and dual-polarized millimeter-wave antenna element design.A new form of dual-polarized millimeter wave antenna is proposed and the loss of its structure is analyzed.On this basis,in order to satisfy the practical application requirements of millimeter wave module in terminal devices,this work adopts a stacked capacitive-feed microstrip antenna as the array element for antenna array research.The dual-band and dual-polarized antenna element can cover the frequency bands of 24.25-28.35 GHz and 37-43.5GHz.In addition,double feeding is adopted to realize ±45° linear polarization.In order to broaden the working frequency band,additional capacitance is brought by cutting two rings on the bottom patch to offset the inductance of the feed.In addition,four curved parasitic strips are introduced around the top patch to generate additional resonant frequency points near the 41 GHz band,so as to broaden the high-frequency working bandwidth.The maximum gain of the antenna element is 5.8d Bi at 28 GHz and 6.2d Bi at 39 GHz.The half power beam width(HPBW)of the antenna element is 112° at 26 GHz and 98° at 39 GHz.(b)Design of four element millimeter wave antenna array.In order to satisfy the beam scanning characteristics of millimeter wave terminal antenna array,a linear array composed of four dual-band and dual-polarized antenna elements is designed,which the element spacing is 4.2 mm(equivalent to 0.36 wavelength at 26GHz).n order to overcome the coupling problem caused by too close spacing,two groups of decoupling structures are designed,which are the I-shaped parasitic resonator between the elements and the C-shaped split ring resonator etched on the floor.The EM simulation results show that the isolation is improved by 6-12 d B compared with the undecoupled structure.The electromagnetic simulation results show that the isolation is improved by 6-12 d B compared with the un-decoupled structure.The measured results show that the antenna array could cover both 24-28 GHz and 36-42 GHz bands,and the isolation of all ports is better than 15 d B.The EM simulation and actual measurement results show that the antenna array can achieve a beam scanning angle of ±63° at 26.6GHz and ±45° at38 GHz,the design of compact dual-band and dual-polarized millimeter wave array antenna is realized.2.A wide-angle scanning millimeter wave array antenna using EBG structure is proposed in this paper.(a)Using the electromagnetic band gap and in-phase reflection characteristics of EBG structure could effectively widen the scanning angle of the array antenna,this paper uses E-shaped patch antenna as the radiation element,due to the EBG structure,the gain of the antenna element is 4.9d Bi,its half-power beam width is 143°,and the antenna element can cover the frequency band of 24.2-27.5GHz.(b)Wide angle scanning array antenna design.Due to the in-phase reflection characteristic of EBG structure,the half-power flap width of the antenna unit is increased by 42°,and in addition,by using its electromagnetic band gap characteristic to suppress surface waves,the antenna element can be grouped with0.4 wavelength,and the simulation and measurement results show that the antenna array could cover 24.2-27.5GHz band,and the scanning angle of the antenna array at 26 GHz can reach ±75°.Compared with the array without EBG structure,the isolation degree is improved by 7d B,the bandwidth is improved by 1.8GHz,the beam scanning capability is improved by 15°,and the array gain is improved by 2.5d B.The design of high isolation wide angle scan millimeter wave antenna array with EBG structure is realized. |
