Control Method And Application Of Time Reversal Focusing Fields Produced By Planar Antenna Array

The research of trapping and manipulating particles by electromagnetic wave has a very important value in exploring the laws of interaction between electromagnetic wave and matter,and expanding its applications in the field of life sciences,colloid physics,particle physics,lab-on-a-chip and other fields.In the meantime,it has a significant impact on the cross-development combined with physics,chemistry,biology and other basic science.To explore trapping and manipulation particles by using electromagnetic waves which are below optical frequencies,based on planar antenna array and TR method,this thesis proposes generating methods of various high-intensity focusing field which include single-point,multi-point and hollow ring,and the mechanical properties of the various high-intensity focusing field are further studied.It is demonstrated that high-intensity focusing fields which are below optical frequencies have the ability to trap and manipulate the Rayleigh particles.The research works of this thesis as follows:Firstly,this thesis proposes a method and a system device for generating single-point high-intensity focusing fields,and studies the influence of P-TRM's arrangement and focusing position on this focusing field.And based on high-intensity focusing fields,we propose a kind of electromagnetic tweezers to trap and manipulate the single Rayleigh particles.We find that it is more favorable for producing high-intensity focusing fields by using double-layer P-TRM,especially the double-layer P-TRM under the same direction of polarization can produce a single-point focusing field with higher electromagnetic intensity,and the resulting focusing field stays unchanged when the position of the focus changes.Furthermore,the mechanical properties of the single-point high-intensity focusing field and its influencing factors are further studied.It is found that the larger the radius of the Rayleigh particles,the larger the gradient force in the single-point high-intensity focusing field.For the high refractive index Rayleigh particles,the larger the relative refractive index between the particles and the environment,the larger the gradient force in the single-point high-intensity focusing field.The single-point high-intensity focusing field can not trap low refractive index Rayleigh particles.Increasing the input power of the P-TRM can increase the gradient force of the single-point high-intensity focusing field on Rayleigh particles.Through numerical simulation,it is theoretically proved that the single-point high-intensity focusing field has the ability to trap and manipulate the high refractive index Rayleigh particles.Secondly,Based on the study of single-point high-intensity focusing fields and the principle of reverse phase field cancellation,a new method of generating high-intensity focusing field is proposed,which can generate a small spacing multi-point high-intensity focusing field that can simultaneously trap and manipulate a number of particles.And in this way,the ability of trapping and manipulatting a number of particles by high-intensity focusing field is drastically promoted.By full wave numerical simulation,generating three-point high-intensity focusing field and its mechanical effect on three a=1mm polystyrene beads are also studied.It is theoretically proved that the multi-point high-intensity focusing field can simultaneously trap and manipulate a number of high refractive index Rayleigh particles.Finally,a method of generating high-intensity focusing field shaping as a hollow ring by the superpositon of two sets of orthogonal double high-intensity focusing fields is proposed,and the effect of the space between the expected focusing points on the hollow ring high-intensity focusing field is studied.Then,the effect of the hollow ring high-intensity focusing field on the low refractive index Rayleigh particles is studied.When the frequency of the electromagnetic wave is 4.3GHz,it is found that the distance between the pre-focus points D of the hollow ring high-intensity focusing field is 43.75mm(27)D(27)87.5mm,and in the range of this space distance,the gradient forces generated by the hollow ring high-intensity focusing field can trap low refractive index Rayleigh particles.