| With the highly diversification of user scenarios for terminal equipment,people have higher requirements for the wireless cellular system and its related mobile antenna configuration.The traditional mobile communication frequency resources are very limited,which limit the data transmission rate and capacity to a large extent.And millimeter wave(mmWave)technology will become the key to improve the data transmission rate and capacity in the future.At the same time,due to the progress of the packaging and integration technology,the terminal mmWave antennas are gradually integrated with the RF components and chip modules.Therefore,the research on end-fire antennas with zero ground clearance becomes popular.In this thesis,according to the practical application background demand of the 5G terminal mmWave antenna,combined with the current development trend,starting from the basic theory,three 5G terminal mmWave antennas have been researched and designed successively.The main work includes:Firstly,a multi-band mmWave horizontally polarized antenna array is designed in this thesis.Comprehensive consideration based on size,bandwidth and pattern,the structure of the microstrip quasi-Yagi antenna is selected as an antenna unit.The-10 dB impedance bandwidths for the return loss are 23.81 GHz to 32.40 GHz and 36.91 GHz to 45 GHz,which can completely cover the bands of n257,n258 and 5G optional frequency band.The gain of the antenna unit in the end-fire direction is greater than 4 dBi.And the gain of the 1 × 4 uniform linear array is greater than 9 dBi in the end-fire direction.The beam scanning range is from-60 degrees to +60 degrees at 27 GHz,and the maximum radiation gain is 9.13 dBi.The beam scanning range is from-46 degrees to +25 degrees at 42 GHz,and the maximum radiation gain is 10.26 dBi.Secondly,in order to ensure the perfect end-fire characteristic of the antenna with zero ground clearance,based on the Snell's law of the refraction,a mmWave antenna with a complete ground is designed.Utilizing the refraction of the radiated waves between different dielectric layers,the up-tilting of the beam in the end-fire direction caused by the complete ground has been solved.The working bandwidth of the antenna unit is 24.25GHz to 29.5 GHz(22.22%),and the gain range is 4.1 dBi to 6.15 dBi in the end-fire direction.Based on the structure of the antenna unit,the 1 × 4 and 2 × 2 arrays are designed respectively.For the 1 × 4 array antenna,the isolation is greater than 17.6 dB,and the gain range in the end-fire direction is 7.51 dBi to 10.2 dBi.Under the condition that the edge angle gain is reduced by no more than 3 dB,the beam scanning range of the array is from-60 degrees to +60 degrees in the xy plane.Finally,based on the theorem of the surface wave,three kinds of the mmWave antennas with zero ground clearance are proposed in this thesis.Once the bound wave is discontinuous or the surface wave gap occurs,it will radiate to the free space to solve the up-tilting of the beam.Firstly,an antenna with the tapered ground plane is designed.The working bandwidths of the antenna are 28.36 GHz to 31.57 GHz and 42.19 GHz to 45.44 GHz.The maximum radiation gain of the horizontal plane is more than 4 dBi.Considering some specific problems in the practical applications,an antenna with the transition dielectric layer is designed,which has a good end-fire characteristic.Finally,based on the theory of the surface wave and the Snell's law of the refraction,an end-fire antenna with the complete ground is designed,which can realize the resonance in the high frequency of 40.5 GHz to 42.5 GHz and it also has a perfect end-fire characteristic.The maximum radiation gain of the horizontal plane is more than 4 dBi. |
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