Multi-port Reconfigurable Antenna Array Desig

In communication and radar systems,antenna is an essential and key component.However,with the rapid development of the fifth-generation mobile communication technology（5G）,sometimes the antenna cannot adapt to the new working environment,thus limiting the performance of the system.Reconfigurable antennas possess a high degree of flexibility,allowing them to seamlessly adjust to variations in the surrounding environment,while also accommodating the demands of modern communication channels in terms of diversity and efficiency.To better adjust to the advancements of the 5G era,this paper designs three reconfigurable antenna arrays based on the method of maximum power transmission efficiency（MMPTE）.The main work includes:1.A low-profile polarization reconfigurable antenna is designed.The antenna is composed of two layers of fan-shaped patches of different sizes.The antenna bandwidth is extended and the profile is reduced by coupling feeding and stacking of two layers of patches.In the overall design,the characteristic mode theory is used to determine the working frequency band of the antenna,and MMPTE is used to obtain the optimal excitation distribution of each port corresponding to various polarization states.Finally,the optimized antenna operates at 3.5 GHz,achieves 13.7%relative impedance bandwidth through 0.058λ₀ profile height,and achieves good directional radiation and polarization reconfiguration effect.2.A wideband tightly coupled polarization reconfigurable array is designed.The array element consists of butterfly dipole,impedance transformer,short circuit strip and tightly coupled structure.The working bandwidth of the array is extended by adding the tightly coupled structure and arranging the array elements in a tight ring.The gain of the array is more stable by using a short circuit strip.Then MMPTE is used to obtain the optimal excitation distribution of each port corresponding to various polarization states.Finally,the optimized array operates at 3.5 GHz with a relative impedance bandwidth of 51.2%,and can achieve good directional radiation and polarization reconfiguration in the broadband range.3.A heterogeneous array with circular polarization wide angle scanning and full coverage is designed.The array consists of two different antenna elements,both of which are in the form of dipoles and can achieve left-handed circular polarization.By changing the spatial position of the elements,a stereoscopic array is constructed,and MMPTE is used to obtain the optimal excitation distribution of each port corresponding to various scanning angles.The optimized heterogeneous array operates at 3.5 GHz with a relative impedance bandwidth of 17.2%.The feature of this array is that it can realize circular polarization wide angle scanning with full coverage by only 7 elements.The maximum scanning angle can reachθ=±60°,and the gain fluctuation and axial ratio of the array are less than 3 d B during the whole scanning process.The three antennas all work in the current 5G Sub-6 GHz frequency band and fully cover the n78 frequency band.It is believed that these three antennas can provide design ideas for the polarization reconfigurable and pattern reconfigurable antennas of 5G communication in the future.