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Resonant Enhancement of THz Radiation Through Vertically Aligned Carbon Nanotubes Array by Applying Wiggler Magnetic Field
摘要： The present analysis develops a novel theory of terahertz radiation generation by beating of two laser beams, incident obliquely on the array of vertically aligned carbon nanotubes (CNTs) in the presence of an external wiggler magnetic field. The array of CNTs behaves as nanoantenna to generate THz radiations. The incident lasers exert a ponderomotive force on the electrons of the CNTs to produce nonlinear oscillatory velocity, which beats with the applied wiggler magnetic field. This beating produces a nonlinear current at (ω2 ? ω1, k2 ? k1 + k0) which acts as an antenna to produce the THz radiation. We observe that when the beat frequency (ω2 ? ω1) lies near the effective plasmon frequency of the CNTs, strong THz radiation is produced due to a resonant interaction of the laser with CNT electrons. The externally applied wiggler magnetic field enhances the efficiency of THz radiation of nanoantenna by providing the necessary momentum to the generated THz radiation. We explore the impact of radius and length of nanotubes on the efficiency of THz generation. The generated THz power is enhanced at an optimum angle of incidence of lasers with an array of CNTs.
关键词： THz radiation,Carbon nanotubes,Antenna theory,Wiggler magnetic field,Plasma,Nanotechnology
更新于2025-09-23 15:23:52
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - AMI Data Quality and Collection Method Considerations for Improving the Accuracy of Distribution Models
摘要： In the 5G system, we foresee the use of LOS-dominated mm-wave radio links to moving users being subject to slow fading resulting from the users’ random locations and orientations. We refer to this as a random-LOS channel. MIMO processing algorithms will be used in 5G to improve performance in slow fading, similar to how they are used in Rayleigh fading. To this end, we study the probability of detection in the random-LOS channel when there are dual-polarized antennas on both sides of the link. We introduce two polarization de?ciencies: the polarization non-orthogonality and the amplitude imbalance between the ports of a two-port antenna. The MIMO ef?ciency is evaluated as a function of these de?ciencies. In the analysis, we consider the MRC algorithm for one bitstream, and the ZF and SVD algorithms for two bitstreams. We also present two analytical formulas for the MIMO ef?ciency that can be used to determine performance. We use the formulas on two ideally orthogonal dipoles, and show by means of coverage plots how much the 1- and 2-bitstream performances degrade due to the polarization de?ciencies in off-boresight directions.
关键词： antenna measurements,line-of-sight,polarization-MIMO,Antenna theory
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS) - Tel-Aviv, Israel (2019.11.4-2019.11.6)] 2019 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS) - Advances in Slotted Waveguide Array Antenna Technology
摘要： We review the state of the art of slotted waveguide array antenna technology. Design and analysis techniques of slot arrays in standard rectangular waveguides are discussed first. Subsequently slots cut in ridge waveguides, iris excited waveguides, strip lines, radial waveguides and gap waveguides are addressed. Some applications of slot arrays and manufacturing techniques are also briefly reviewed.
关键词： Slot arrays,antenna theory,slotted waveguide,antenna design,array analysis and optimization
更新于2025-09-19 17:13:59
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Antenna Effective Area for Spherical Waves
摘要： Antenna power response to incident waves can be described with the effective area. While the effective area widely used is for uniform plane waves, the effective area can be de?ned also for uniform spherical waves. We introduce the effective area as a function of the direction and the curvature of an incident wave. The spherical-wave effective area is suitable for the antenna fundamental relation and the Friis transmission formula, and extends their interpretation.
关键词： antenna theory,reciprocity,antenna property
更新于2025-09-04 15:30:14
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Optimization of Far-field Radiation from Impedance-Loaded Nanoloops Accelerated by an Exact Analytical Formulation
摘要： Impedance loading is a common technique traditionally used in the RF to enhance the performance of an antenna, but its application in the optical regime is not as rigorously studied. This is mainly due to a lack of exact analytical expressions that can be used to rapidly predict the radiation properties of loaded nanoantennas. This paper will derive a set of useful analytical expressions for the far-field radiation properties of loop antennas loaded with an arbitrary number of lumped impedances that are valid from the RF to optical regimes. The analytical expressions will be validated with full-wave solvers and can be evaluated more than 100x faster. The ability to perform such rapid evaluations enables, for the first time, large-scale single- and multi-objective optimizations. A series of optimizations reveal that electrically small super-directive antennas can be achieved at a variety of far field angles through capacitive loading, paving the way for a pattern reconfigurable antenna. In addition, gains of greater than 3 dB can be achieved for electrically small antennas over a fractional bandwidth of 28%. Finally, it is shown that impedance loading can be used to achieve circularly polarized radiation from a single loop.
关键词： Loop antennas,Antenna theory,Optimization,Nanotechnology,Submillimeter wave technology
更新于2025-09-04 15:30:14