Research On Reconfigurable Metasurface Design For Wireless Communication Applications

The fifth-generation mobile communication(5G)technology has the characteristics of low latency,high throughput and high transmission rate.However,the disadvantages of high cost,high energy consumption and random wireless channels limit its application in practical scenarios.As 5G mobile communications continue to be commercialized,research on the sixthgeneration mobile communication(6G)technology is also in progress.The main development directions of the 6G communication system are higher communication rate,higher spectrum utilization,low power consumption and controllable wireless environment.Reconfigurable metasurfaces have great potential for 6G applications due to low cost,low power consumption,low complexity,and flexible control of electromagnetic scattering properties.However,reconfigurable metasurfaces are confronted with problems,such as the shortage of spectrum resources,the accuracy of electromagnetic wave transmission directions,and also the deployment requirements of different communication operators.Therefore,in this thesis,the research of angle-stabilized,dual-band and dual-polarized reconfigurable metasurfaces is carried out to address the above problems.The main contents are summarized as follows:(1)A dual-polarized angle-insensitive reconfigurable metasurface is designed for ultrahigh frequency(UHF).The phase modulation is realized by controlling bias voltages of varactor diodes.Angular stability is achieved by adding metal vias around the unit-cell.This design satisfies the phase tunning range of 340° in the frequency band of 374.6-427.4MHz.It also obtains good angular reciprocity under oblique incident cases,thereby is beneficial to be applied in the communication systems of this frequency band.(2)A single-polarized,dual-band,independently phase-modulated reconfigurable metasurface is designed.Based on the resonant structures of two loaded varactor diodes,surrounded by metal vias,the unit-cell finally realizes dual-band independent phase modulation in the frequency bands of 2.515-2.675 GHz and 3.4-3.5GHz.The maximum phase tuning range is315° with good angular stability.It has been verified by measurement results that the design can independently control the beams of two frequency bands within the incident angle of50°,which is beneficial to meet the deployment requirements of different communication operators in the future mobile communication system.(3)A reconfigurable metasurface with dual-polarization and dual-band independent phase modulation is designed.Based on the design method of 2.5-dimensional metasurfaces,the unit-cell uses two dual-polarized resonant structures loaded with varactor diodes to achieve independent phase control in the frequency bands of 2.515-2.675 GHz and 3.4-3.5GHz,respectively,satisfying 3-bit quantitative requirements,and can maintain a stable electromagnetic response under the oblique incidence of electromagnetic waves.In addition,the unit-cell can individually modulate the phase response of x-polarized and y-polarized electromagnetic waves.Measurement results demonstrate that the metasurface is capable of achieving angular reciprocal beam manipulation in dual-frequency bands within 45° of the oblique incidence.The design is suitable for applications in complex electromagnetic environments and can improve the spectrum utilization of the wireless channel.