Research On Radiation Characteristics Of The Macroscopical Form Of Carbon Nanotubes In Terahertz Band

Taking advantage of the features of small radius, high strength and high toughness,CNTs have been employed in a wide range in the field of nanometer(NM) system. Thewell ability in current-carrying and electric-conducting made it proper to take CNTs asdevice for message receiving and transmiting between macroscopic system and NMsystem fast and vastly. Due to the characteristics of quantum mechanics on CNTs,general calculation software always sounds helpless in simulating the common fact.Moreover, the development of CNT in the Electromagnetic field is severely limited byits high impedance and instability in growing. In order to analyze the electromagneticfeatures of CNT essentially, this paper combines the theorys of quantum mechanics andelectromagnetism while completes both the theoretical analysis and NumericCalculation for the scattering of CNTs. The rules for changing of the width of scatteringare obtained. Antennas consist of CNTs are also stated to get the current distribution andcondition of far field, which provides theoretical foundation for the applications inoptics, biomedicine and antenna research.The main content of the paper is divided into two parts: the properties of scatteringof CNTs under the inspiration of plane wave and the radiation characteristic of dipoleantenna made of CNTs.Firstly, the paper is based on the scattering theory of Mie while uses theexpressions and boundary conditions got from the derivation in the quantum mechanicsfor reference. The resolving expressions of scattering field, transmitting field andscattering width are also achieved for one-armed CNTs under the inspiration of incidentwave with different polarization directions and incident angles. The comparisonbetween the results of calculation and test are accomplished, which checked theeffectiveness of the theory of Mie for CNT scattering. The results indicate that reflectingwave brought by resonance emerged in the range of THz when the polarization ofincident wave is set to be TM and normalized regardless of the incident angles. On theother hand, the TE model will result in the reflection in infrared band for the normalizedincident wave between60°-120°.Secondly, for the reason that the efficiency of radiation of one-armed CNTs is solow, this paper also got calculated the multi-armed CNTs under the exposure of incidentwave with TM polarization and vertical direction. And the comparison and analysis ofscattering width of CNTs with different number of layers are finished. The resultsindicate that the increasing of layer number can improve efficiency of radiation of CNTantenna effectively while has little influence on the frequency of radiation.Thirdly, the paper puts forward7models consist of CNTs and medium to improvethe directivity pattern of CNT antenna and such is a idea dues to the fact that CNTs are rarely employed alone. The mentioned models include all the possible combination ofthe two materials. Furthermore, the calculation of electromagnetic features for the CNTswith different medium is based on the theory of Mie. The results are also compared toverify the feasibility of increasing the scattering characteristics of CNTs and materialperformance of medium by loading each other. By the same time, the research alsooffers some theoretical basis for the application in Biomedical Sciences.In the end, it is difficult to study the CNTs with the tools of common simulatingsoftware for the microcosmic performance of CNTs. To solve such a problem, this paperbuilds one equivalent transmission line model with two CNTs using the microcosmicfeature of CNTs primarily. Considering the theories of circuitry and transmission line,the expressions of current distribution, the far field and the radiated energy are derivedunder the condition of little loss. The mentioned results provided strong theoretical basisfor the fabrication and test of CNT antenna.