Research And Calculation Of Pattern Reconfigurable Impeller Type Terahertz Antenna

The reconfigurable antenna can adjust the characteristic parameters of the antenna according to the change of communication environment in real time.It can not only meet the requirements of high rate and variable channel for modern communication,but also reduce the number of antennas in the communication platform and purify the electromagnetic environment,which is the forefront subject in the antenna field.Traditionally,the reconfigurable antenna has been implemented in many ways,such as loading electronic devices or using mechanical methods,but the structure is very complicated with low efficiency.Graphene,just emerged in recent years,has unique photoelectric properties and high efficient electrical tunability.Its working frequency covers the terahertz band,which provides an effective way to design reconfigurable terahertz antenna.A novel pattern reconfigurable impeller type terahertz antenna based on monolayer graphene is designed in this paper.The antenna is calculated and optimized by method of moments.Results show that the radiation beam of the antennacan vary in a range of 360° continuously and the antenna has a moderate gain and low backward radiation.Below are the main points of the paper:(1)The basic properties of graphene are reviewed.Two kinds of antennas based on graphene materials such as dipole antenna and Yagi Uda antenna are calculated.The far field radiation characteristics of the antennas are given and compared with those of antennas made of perfect conductor.This provides a theoretical basis for the application of graphene in the reconfigurable antenna design.(2)A novel impeller type terahertz antenna based on graphene is designed in order to implement the reconfiguration of the pattern.The main structure of the antenna consists of a graphene dipole as an active oscillator and several graphene sheets which are distributed evenly in the circumferential direction with the dipole as the center.The antennas with 2?9 blades are calculated and optimized to explore the relationships among the number of blades,the chemical potential distribution of the blades and the radiation characteristics of the antennas.The regularities are summarized as follows:the impedance state of the graphene blades regulated by chemical potentials determines the direction of beam of the antenna main lobe.The blades backing the beam are in the low impedance state and act as reflections while the blades facing the beam are in the high impedance state and act as transmission windows.(3)Based on the mentioned regularities,the chemical potential distribution trapezoidal equivalent function is established taking distribution of the chemical potential of the antenna with 45 blades as an example and the validity of the equivalentfunction is verified.That the beam of the antenna can be rotated in a range of 360°continuously is realized and the beam scanning range covers the full azimuth plane.The antenna with 45 blades is optimized through the chemical potential distribution trapezoidal equivalent function.Calculation results show:the radiation gain of the antenna is 8.46dB and the front-to-back ratio is 31dB.The backward radiation is effectively suppressed.The trapezoidal equivalent function adopted is also applied to the optimization of impeller type terahertz antennas with other blades.The impeller type terahertz antenna designed in this paper has the advantages ofsimple structure,small volume,360° omnidirectional beam scanning and fast response which can provide a competitive alternative for the design of wireless communication system among terahertz devices.