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- 摘要
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- 实验方案
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Intense THz Source of Sub-Cycle Pulses with Tunable Elliptical Polarization
摘要： We propose a new THz source based on a large aperture photoconductive antenna for the generation of intense THz waves with tunable elliptical polarization. We designed an interdigitated structure with vertical and horizontal electrodes to produce half-cycle THz pulses with horizontal and vertical polarizations, respectively. A time delay between the two polarizations is introduced using a quartz window deposited onto the parts of the antenna with horizontal electrodes forming a phase mask. We demonstrate the generation of sub-cycle THz pulses with tunable elliptical polarization and a 70 kV/cm electric field. We show that the polarization state can be varied from linear to quasi-circular.
关键词： elliptical polarization,photoconductive antenna,sub-cycle pulses,THz source,tunable polarization
更新于2025-09-23 15:22:29
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Metamaterial based circularly polarized hexa-band patch antenna with small frequency ratios for multiple wireless applications
摘要： In this article, a novel shaped hexa-band microstrip patch antenna (MPA) is presented. The proposed antenna offers six frequency bands including 2.4, 3.06, 3.34, 3.54, 4.61, and 5.21 GHz with very small frequency ratio between two consecutive bands of the value of 1.275, 1.091, 1.059, 1.3022 and 1.1301, respectively. The proposed antenna also shows better radiation characteristics at all six bands and circular polarization at two frequency bands from 2.36 to 2.48 GHz and 4.52 to 4.64 GHz. Design steps for achieving all six bands are presented in detail and simulated results are verified with experimental results of the fabricated prototype.
关键词： microstrip antenna,inter digital capacitor loaded loop resonator (IDCLLR),rectangular split ring resonator,dipole,Circular polarization
更新于2025-09-23 15:22:29
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Effective light polarization insensitive and omnidirectional properties of Si nanowire arrays developed on different crystallographic planes
摘要： In this paper, fabrication of vertical Si nanowire arrays (SiNWAs) by a facile metal assisted electroless etching approach on different crystallographic planes of Si has been reported. A very low specular reflectance (Rspec) of 0.04% and 0.03% has been achieved in the whole visible range for SiNWAs grown on Si(100) and Si(111) oriented substrates, respectively. High broadband enhancement has been detected for vertical SiNWAs due to multiple scattering paths inside the nanowire arrays. On the other hand, inclined nanowires showed a fascinating behavior at the longer wavelength regime, where light gets the longer path to reflect back-forth and ease to reflect back outward at normal incidence. Moreover, for [100] SiNWAs, transverse electric (TE) field component demonstrates the strong polarization insensitive properties at the expense of transverse magnetic (TM) field component with a minimum reflectance of < 2% up to 1200 nm. The [100] SiNWAs demonstrates extra-ordinary omnidirectional properties at θB ≥ 58o. Theoretical validation of COMSOL with an effective medium approach reveal the effective dipole coupling and the presence of strong absorption modes for vertical SiNWs at a typical wavelength regime. The highly bound states of the particle tunneling through classical forbidden region shows a strong enhancement in light absorption effect.
关键词： nanocavities,Si nanowires,light coupling effect,omnidirectional,polarization
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - A Novel Circularly Polarized Yagi Antenna
摘要： This paper presents a novel circularly polarized Yagi antenna, consisting of a reflector patch, an oscillator patch, two director patches and two conductor rings. Through the use of Yagi antenna structure and conductor ring structure, antenna gain has been improved. The simulation results show that the antenna has a gain of about 9dB, which is about 4dB higher than that of the existing patch antenna.
关键词： Yagi antenna,circular polarization,conductor ring,stacked patch
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on RFID Technology & Application (RFID-TA) - Macau, Macao (2018.9.26-2018.9.28)] 2018 IEEE International Conference on RFID Technology & Application (RFID-TA) - Polarization Reconfigurable Antenna with Beam Steering Performance
摘要： This paper proposed a novel method reconfiguring the polarization of the dielectric resonator antenna (DRA) with beam steering performance. During the process of liquid alteration between the two zones of the 3-D printed container, the proposed antenna performed with beam steering performance. What's more, the polarization was switched with the beam steering process. The proposed design is suitable for the application as a RFID reader.
关键词： dielectric resonator antenna,Radio frequency identification (RFID),polarization reconfigurable,beam steering
更新于2025-09-23 15:22:29
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Electromagnetic sinc Schell-model vortex beams
摘要： We introduce a new class of electromagnetic Schell-model source in which the cross-spectral density matrix possesses a sinc correlation function and a separable phase. The far-field radiation properties for the electromagnetic sinc Schell-model vortex beams generated by such source are investigated. It is shown that the far-field distributions of all statistical characteristics of such a beam possess vortex structure, depending on the topological charge and the correlation length of the source field.
关键词： electromagnetic vortex beams,polarization,Coherence
更新于2025-09-23 15:22:29
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Pseudo-polarimetric method for dense haze removal
摘要： The scattering and absorption by the existing particles in turbid media severely degrading the image quality and decreasing the visibility distance, especially in dense turbid media. In this paper, we investigate the polarization property of hazy images in dense turbid media, and we propose a simple pseudo-polarimetric dehazing method for dense haze removal, which only requires a single image captured by the detector. By our proposed method, two orthogonal polarization sub-images are derived from the single original image, and then, based on these two sub-images, one can obtain the recovered image by using traditional polarimetric method. The real-word experimental results verify that, for the dense haze, our method based on a single image could have a comparable or better performance compared to the traditional polarimetric dehazing method with multiple images captured at different polarization states.
关键词： polarimetric imaging,Polarization,imaging through turbid media
更新于2025-09-23 15:22:29
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Characterization of Polarization Pulling in Fiber Optical Parametric Amplifiers
摘要： In fiber optical parametric amplifiers (FOPAs), the output states of polarization (SOPs) of both the signal and the idler are affected by the pump SOP through the polarization pulling effect. We proposed a normalized model to characterize the general dynamics of polarization pulling in degenerated pump FOPAs. By using this model, we determined the relationship between the output degree of polarization (DOP) and the gain of the FOPAs over three orders of magnitude changes in polarization-mode dispersion (PMD) coefficient. We demonstrated numerically that when fibers with typical PMD coefficients are used, the output signals of the FOPAs can achieve higher DOP than those of co-propagating fiber Raman amplifiers, which depends on whether the parametric gain is sufficiently large to compensate the PMD-induced phase mismatch. We also found that for FOPAs using different types of fibers with moderate PMD coefficients, this DOP-gain relationship exhibits highly similar behaviors. We thus adopted a set of modified empirical formulas to analyze this relationship. This formula can also describe the relationship between the output DOP and the conversion efficiency of the idler. The results indicate that in all cases studied, FOPAs achieve much stronger polarization pulling to the idlers than the signals.
关键词： Nonlinear optics,parametric oscillators and amplifiers,polarization-selective devices
更新于2025-09-23 15:22:29
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Dual-Polarized Phased Array Based Polarization State Modulation for Physical-Layer Secure Communication
摘要： In this paper, a dual-polarized phased array based polarization state modulation method is proposed to enhance the physical-layer security in millimeter-wave (mm-wave) communication systems. Indeed, we utilize two polarized beams to transmit the two components of the polarized signal, respectively. By randomly selecting the transmitting antennas, both the amplitude and the phase of two beams vary randomly in undesired directions, which lead to the PM constellation structure distortion in side lobes, thus the transmission security is enhanced since the symbol error rate increases at the eavesdropper side. To enhance the security performance when the eavesdropper is close to the legitimate receiver and located in main beam, the artificial noise based on the orthogonal vector approach is inserted randomly between two polarized beams, which can further distort the constellation structure in undesired directions and improve the secrecy capacity in main beam as well. Finally, theoretical analysis and simulation results demonstrate the proposed method can improve the transmission security in mm-wave communication systems.
关键词： dual-polarized array,polarization state modulation,physical-layer secure communication
更新于2025-09-23 15:22:29
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PolSAR Coherency Matrix Optimization Through Selective Unitary Rotations for Model-Based Decomposition Scheme
摘要： In this letter, a special unitary SU(3) matrix group is exploited for coherency matrix transformations to decouple the energy between orthogonal states of polarization. This decoupling results in the minimization of the cross-polarization power along with the removal of some off-diagonal terms of coherency matrix. The proposed unitary transformations are utilized on the basis of the underlying dominant scattering mechanism. By doing so, the reduced power from the cross-polarization channel is always concentrated on the underlying dominant co-polar scattering component. This makes it unique in comparison to state-of-the-art techniques. The proposed methodology can be adopted to optimize the coherency matrix to be used for the model-based decomposition methods. To verify this, pioneer three-component decomposition model is implemented using the proposed optimized coherency matrix of two different test sites. The comparative studies are analyzed to show the improvements over state-of-the-art techniques.
关键词： Coherency matrix,polarimetric synthetic aperture radar (PolSAR),cross-polarization,unitary matrix rotation,land-cover classification
更新于2025-09-23 15:22:29