Tunable Feeding Network And Its Application In Reconfigurable Antenna Array

At present,the design of communication system is developing towards miniaturization and multi-function.However,the traditional communication system has complex structure,large volume and single function,which can not meet the development requirements of communication system.Reconfigurable communication systems can solve the problems that multiple communication systems can solve,and can achieve miniaturization and multi-functional integration.Therefore,the research on reconfigurable communication systems has become a trend of development.With the increasing number of mobile phone users,the demand for data services shows an exponential growth trend,and the contradiction with the shortage of spectrum resources is becoming increasingly prominent.Therefore,the fifth generation mobile communication(5G)emerges as the times require.Beamforming is one of the key technologies in 5G communication system.At present,beamforming is mainly achieved by antenna array.The radiation characteristics of the antenna array are mainly determined by its feeding current distribution,and the feeding current distribution is controlled by the feeding network.Therefore,in order to meet the requirements of miniaturization,multifunction and beamforming of modern communication systems,it is very important to study the design and implementation methods of the feeding network that can meet the requirements of reconfigurable beamforming antenna array.In this paper,the tunable feeding network and reconfigurable beamforming antenna array used in the 5G communication system are studied,and the following results are obtained:(1)A 2-way tunable power divider working in the frequency range of 3.4GHz to 3.6GHz is designed.The power divider is based on the structure of hybrid ring and is designed by loading two varactor diodes in the circuit.The power dividing ratio of the divider is controlled by a DC bias voltage,the simulation results show that its power dividing ratio can be continuously adjusted in the range of-17.5dB?8.5dB and each port of power divider matches well and the phase difference of output port changes little.On this basis,a 4-way tunable power divider is designed,which can feed the 4-element antenna array and realize the adjustable amplitude of the feeding.The above two kinds of power dividers are fabricated and tested,and the test results are in good agreement with the simulation results.(2)A tunable 1-way phase shifter working in the frequency range of 3.4 GHz to 3.6 GHz is designed.The phase shifter is based on a branch line coupler structure and is designed by loading varactor diodes at two load ends.The two varactor diodes are controlled by a DC voltage to control the phase shift of the circuit.The simulation results show that the phase shift of the tunable phase shifter is continuously adjustable and can reach 190°.On this basis,a 4-way tunable phase shifter is designed to provide the changed excitation phase for the 4-element antenna array,and the phase adjustment of the feeding is realized.The 4-way tunable phase shifter is fabricated and tested.The test results are in good agreement with the simulation results.(3)In order to verify that the tunable feeding network designed in this paper can reconfigure the pattern of beamforming antenna array,a 4-element microstrip patch antenna array with a central frequency of 3.5 GHz is designed.A four-element antenna array with a center frequency of 3.5 GHz is designed by using microstrip patch structure.Four typical beam-shaped antenna arrays are used(uniform antenna array with excitation distribution ratio of 1:1:1:1,sector-beam antenna array with excitation distribution ratio of 1:5.9:5.9:1 and high power fraction antenna with excitation distribution ratio of 8:1:1:8).Asymmetric beam antenna array with excitation distribution ratio of 1:2:4:8)as an example,the tunable feeding network designed in this paper is used for feeding.The results show that the adjustable feeding network designed in this paper can meet the feeding requirements of shaped beam antenna array and realize the reconfigurable function of antenna array pattern,so it has great practical value.