Research On Millimeter Wave Arrays And Metal-Only Broadband Miniaturized Antennas

With the rapid development of cellular communication technology,the Fifth-Generation(5G)mobile communication with its higher data rate,lower transmission delay,greater bandwidth,and other advantages has been widely concerned.Whether in the millimeter-wave band or traditional mobile communication band,higher requirements are put forward for the antenna's broadband and multi-band operation capabilities.The design of a high-performance broadband or multi-band antenna unit and array can meet multiple frequency bands'requirements,which has good application prospects and economic value.In this dissertation,how to realize the miniaturized unit and array with broadband or multi-band is intensely studied and explored.The main contents of the work are summarized as follows:1.To solve the problem of how to realize the dual-polarization end-fire radiation antenna with a wideband and low profile with a complete ground,a broadband dual-polarized end-fire millimeter-wave antenna array is proposed for 5G communication terminals.A multilayer dielectric plate for which the relative dielectric constant increases from top to bottom is used to achieve the antenna's end-fire radiation with a complete ground.Horizontally polarized(HP)and vertically polarized(VP)radiation are realized using a quasi-Yagi antenna and a substrate-integrated waveguide(SIW)horn antenna,respectively.The VP antenna is implemented using the HP antenna,ground,and three rows of metallic vias.The HP and VP antennas are located in the same area,making the integrated design very compact.An inverted L-shaped feeding structure is used to broaden the VP antenna's bandwidth with a low profile.The size of the designed unit is 6.5×6.1×1.48 mm~3(0.53?_L×0.49?_L×0.12?_L,?_L is the wavelength corresponding to the lowest working frequency).Finally,a 4×1 array is processed to verify the proposed antenna.The measured results show that the overlapping bandwidth is 24?29.5 GHz(20.6%)for two polarization modes.The maximum gain varies between 7.6?9.1 and 6.5?9.1 d Bi for the HP and VP modes,respectively.2.To deal with insufficient band coverage and the large size of the broadside radiation millimeter-wave array antenna,a low-profile millimeter-wave magneto-electric dipole antenna element and its array with wide bandwidth is presented and tested.The unit is fed by twin lines located on the same dielectric plate as the shorted patches,making the antenna has a low profile(0.1?_L).Furthermore,the bandwidth of the antenna can be enhanced by using the butterfly patch and staggered arrangement.The impedance bandwidth of the designed unit is 23.9?46.75 GHz(64.7%),and the broadside gain is 5.5±1.1 d Bi.Then,a power divider based on the printed ridge gap waveguide(PRGW)is used to excite the 1×4array.And the influence of electromagnetic band-gap(EBG)arrangement on the transmission line performance is analyzed.Finally,the designed array is processed and tested.The measured results are in good agreement with the simulated ones,showing that the working bandwidth of the array combined with the feed network can cover 24.5?40 GHz(48%),while the broadside gain is 7.7?12.7 d Bi.3.For the problem of multi-band and multi-polarization antenna design in the communication system,a dual-band dual-circularly polarized magneto-electric dipole antenna array is proposed,fabricated,and tested.The proposed array can simultaneously achieve left-hand circular polarization(LHCP)around 20 GHz and right-hand circular polarization(RHCP)around 30 GHz with a low loss feed network using the PRGW.The antenna comprises two sets of stacked interconnected short-circuit patches operating at different frequencies and fed by the same gap.The LHCP at the 20 GHz band and RHCP at the 30 GHz band are realized by exciting the corresponding orthogonal electric-dipole mode and magnetic-dipole mode with-90°/90°phase difference.A cylindrical cavity consists of a series of metalized vias with a top metal strip used for surface wave inhibition.By using the PRGW,a four-way power divider with a low transmission loss is designed.Finally,the simulated 2×2 array was fabricated and measured.The measurement results show that the impedance bandwidths are 18.85?20.8 and 29.5?30.9 GHz.The 3-d B axial ratio bandwidths are 19.4?20.4 and 28.5?31.4 GHz,with peak gains of 13.2 and 11.5 d Bic,respectively.4.To realize the miniaturization of broadband double-ridged horn antenna,the ridge structure with a gradual change in width and the improvement of horn shell are proposed to reduce the antenna's cut-off frequency.Based on the analysis results,two kinds of miniaturized broadband double-ridged horn antennas with the size of 0.065?_L~3 and 0.081?_L~3 are designed and fabricated,respectively.The two antennas work in the band of 2?11GHz and 6?18 GHz,respectively.Further,a low profile metal-only unbalanced feed array is studied.The unit's miniaturization is realized by combining the radiation structure's modification with gradual width and short-circuit branch loading technology.Furthermore,the array's cut-off frequency is reduced by the strong coupling between the small spacing elements,and the common-mode current resonance problem in the unbalanced feed array antenna is analyzed and improved.The designed 7×7 array achieves a relative bandwidth of100%,the aperture efficiency of the array is 90.3?97.4%,and the profile is only 0.185?_L.