Research And Design Of The Novel Planar Reflectarray Antenna

In the fields of satellite communications,space exploration and radar detection,it is always need high gain and directionality of the antenna to deal with the problems of long communication distance and complex space environment.The reflectarray is a novel type of high gain antenna.It can not only achieve specific beam pointing,but also has simple structure,avoiding the design of complex feeding network.Thus,the reflectarray has broad application prospects.Meanwhile,how to make full use of limited spectrum resources has become a key problem to be solved.Due to its unique mode orthogonality,orbital angular momentum can simultaneously obtain multiple OAM electromagnetic signals with different modes at the same frequency,which has attracted wide attention of scholars worldwide.The reflectarray can realize different phase distribution by controlling the size of the element or rotating the unit at an appropriate angle,which can flexibly generation OAM waves with different modes.This thesis mainly focuses on the design of the novel reflectarray antenna and OAM reflectarray antenna.The main research works are summarized as follows:(1)Graphene-based terahertz reflectarray antenna is designed and studied.Firstly,according to the graphene has better performance and reliability in high frequency and small size environment,a graphene-based terahertz circular polarized reflectarray antenna is designed by using graphene instead of metal material and the element rotation technique.Then,by utilizing frequency selective surface(FSS)to replace metal ground and graphene as the radiation patch to reduce the coupling between high and low frequency elements,a dual-frequency graphene circularly polarized reflector array antenna is designed.(2)The reconfigurable reflectarray antenna is designed and studied.F irstly,according to the physical characteristics that the complex conductivity of graphene can be controlled with the chemical potential,the graphene-based FSS is employed as the ground.By adjusting the electric field,which in turn changes the phase and the resonance point of the reflected or transmitted wave at the element.A reconfigurable reflectarray/transmitarray antenna is designed.Then,FSS is also used to replace the metal ground,and the multiple PIN diodes are added to the FSS.The novelty of the proposed design lies in its reconfigurable transmission/reflection,which switches from a bandpass response to perfect reflection,with the control of the biasing states of the PIN diode.The designed antenna can be dynamically reconfigured between the reflectarray/transmitarray antenna.(3)The orbital angular momentum antenna is designed and studied.Firstly,combining the design method of orbital angular momentum antenna and the transmitarray antenna,an OAM transmission array antenna with multiple modes is designed by changing the size of transmission element to control the transmission phase.Then,combining the characteristics of orbital angular momentum and circular polarization,a wideband circularly polarized reflectarray antenna for generation of orbital angular momentum vortex wave is designed by optimizing the element parameters to expand the bandwidth and compensating the required phase using the rotating element method.Finally,a dual-frequency graphene unit is designed by utilizing FSS and graphene as the ground and radiation patch,respectively.By adjusting the surface conductivity of graphene to control the reflection and transmission coefficients of the element,the designed reflectarray can produce an OAM vortex waves at both frequencies.