Microwave And Millimeter Wave Focusing And Shaped Beam Antenna Array Technology Based On Amplitude And Phase Control

As the near-field region of antennas have received more and more attention in recent years,academia and industry are paying more and more attention to near-field focusing and shaped beam antennas.Near-field focusing antennas have a wide range of requirements in practical applications,such as near-field wireless power transmission,near-field detection,remote sensing,and near-field high-resolution imaging.On the one hand,the use of near-field focusing antennas for near-field power transmission can effectively reduce diffraction effects and energy waste.It improves energy utilization efficiency and achieves the purpose of efficient energy transmission in the near field.On the other hand,it can also increase the power density and improve the quality of nearfield communication,near-field high-resolution imaging.The near-field shaped beam technology can also be used in practical applications such as near-field indoor detection,near-field radio frequency identification(RFID),and secure communication.At present,in response to the needs of near-field focusing and near-field shaped beam,researchers have proposed solutions for multiple antenna forms including lenses,phased arrays,and leaky-wave antennas.However,some antenna forms still have problems such as high profile,large loss,insufficient power density at focal spot,and inability to effectively avoid obstacles.In order to solve above issues,the main contributions of this dissertation are as follows:1.Aiming at the problem of insufficient power and resolution at the near-field focal spot,this dissertation proposes a method combining Taylor synthesis with traditional phase superposition based on the theory of geometric physics and optical physics,and establishes a patch focus array model.Through simulation and analysis,the focus characteristics of Tylor synthesis focus array and the traditional focusing array are compared.The results show that the focus performance of the antenna is evidently enhanced since the magnitude of the field at the center of the focal spot has been significantly improved,and2.Aiming at the bad focus performance of the traditional control mode applied in antenna array and insufficient communication signal density,this paper proposes the control mode by adjusting the antenna array element's radiation pattern and phase superposition based on the theory of geometric optics and physical optics as well as the basic working principle of the Cassegrain reflector antenna.The Cassegrain reflector antenna array model is established,the simulation and experimental comparison analysis of multiple control mode show that beam-phase focusing control mode can significantly improve the power density of receiving aperture's center in the near-field region.This control mode solves the problem of low power density caused by the traditional high-gain control mode in wireless power transmission and near-field communication.3.Aiming at the shortcomings of high profile,high loss of the transmitarray antenna and based on the basic working principles of nondiffracting beam as well as the reflection array antenna,this dissertation analyzes the geometric characteristics of the ring focus subreflector's surface and the phase of the reflection array unit to generate the nondiffratcing beam.According to the phase-size response,a scheme for generating nondiffraction beams by the ring-focus reflector antenna is proposed.The low-profile and nondiffraction characteristics of the model and prototype antennas are verified through simulation and experimental verification,which solves the problem of achieving nondiffraction beams at low profiles for optical-feed system.4.Aiming at the problem of near-field shaped beams with obstacles and it is hard to achieve beam scanning for,this dissertation proposes a novel field-circuit combination method based on the equivalent circuit theory of series-fed patch antennas and the generation theory of accelerated self-bending beams.The joint analysis method helps to establish the model of a one-dimensional series-fed patch antenna,and uses the phase accumulation characteristics of the traveling wave of the leaky-wave antenna to realize the 1-D accelerating and self-bending beam with the frequency scanning ability.This is the first time that the self-bending beam with scanning ability is synthesized at Ka-band.