Research On Broadband Patch Antenna And Magnetoelectric Complementary Dipole Antenna For 5G Base Station

5G communication has been gradually put into practice from the initial conception.Compared with 4G,5G system has the advantages of high speed and low delay,but it also has the defect of signal attenuation.The performance and quantity of base station antenna also have higher requirements and demands.On the one hand,in order to improve the communication capacity of the system and save the construction cost,the base station antenna needs to have the characteristics of wide band,multi-frequency band and small size.On the other hand,in order to ensure the communication quality of indoor places,a certain number of indoor distributed base station antennas need to be set up to provide power compensation,so as to reduce the impact of signal attenuation.In addition,the current 5G base station antenna is not sufficient in terms of spectrum coverage,and the working band range needs to be further expanded.Based on these problems,this paper studies the 5G indoor and outdoor base station antennas,and the specific research contents and achievements can be summarized as follows:1)A single polarized wideband magneto-electric dipole antenna is designed.The antenna is mainly composed of two pairs of polygonal patches stacked and a short circuit patch perpendicular to the metal ground.Where the polygonal patch resonates as an electric dipole,and the short circuit patch and the metal ground between them are equivalent to a magnetic dipole.Two inverted L-shaped feeders are used for coupling feeding,and the resonance and matching are flexible and adjustable.The simulation results show that the-10 d B impedance bandwidth of the antenna is 54%（2.93-5.10 GHz）,and the voltage standing wave coefficient is less than 1.7 in the whole frequency range.2)A compact dual polarization wide band magneto-electric dipole antenna is designed.The antenna is equipped with magneto electric dipoles loaded with rectangular slots,which achieve dual polarization through cross placement.Two inverted L-shaped feeders are coplanar with the vertical patch,making the antenna more compact in transverse size.The actual size is 0.57λ_min×0.57λ_min（length×width）.According to the measured results,the working frequency band of the antenna is 3.06-5.28 GHz and the bandwidth of-10 d B is53.2%.The isolation between ports is less than-22 d B over the entire frequency range.In addition,metal baffles are used around the ground to stabilize radiation patterns and improve the front-to-back ratio,with gains greater than 8 d Bi in the frequency band.Meanwhile,for base station applications,the half-power beam width exceeds 65°±5°.3)A vertically polarized low profile wideband patch antenna is designed.The antenna avoids the traditional high cost multi-layer antenna technology and is a low cost configuration.It consists of a center fed circular patch with four short pins appropriately excited TM₀₁ and TM₃₁ radiation modes.Four fan-shaped slots of the same size are loaded into the radiator to further expand the bandwidth and improve the input impedance.The test results show that the-10d B bandwidth of the antenna is 49.6%（3.26-5.41GHz）,which completely covers 5G-n78（3.3-3.8GHz）,n77（3.3-4.2GHz）and n79（4.4-5 GHz）bands.The voltage standing wave coefficient is less than 1.8 in the whole working frequency band,which has good matching characteristics.4)A horizontally polarized wideband thin patch antenna is designed.A planar printing structure composed of single-layer dielectric substrate is proposed.At the bottom,six Vivaldi slot antenna units are loaded on the substrate to realize omnidirectional radiation.An equal 1:6 power distribution network is printed at the top of the substrate to provide an even feed.In addition,rectangular slots are etched into each radiating element to help increase gain at high frequencies and improve impedance matching.The antenna has 58.8%impedance bandwidth（2.8-5.13 GHz）,0.009λ_min low profile height,convenient installation under the ceiling of buildings,and can well radiate indoor places.The radiation mode in the whole working band is stable,and the cross polarization is less than-20 d B,which completely covers the 5G NR-n77/78/79 band.