- 标题
- 摘要
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- 实验方案
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[IEEE NAECON 2018 - IEEE National Aerospace and Electronics Conference - Dayton, OH, USA (2018.7.23-2018.7.26)] NAECON 2018 - IEEE National Aerospace and Electronics Conference - Impact of dielectric and magnetic losses on the negative index characteristics of a chiral material with first-order sideband dispersion
摘要： Electromagnetic propagation in chiral materials under first-order dispersion is examined for negative indices under non-conductive losses. Three loss scenarios are considered, viz., dielectric (complex permittivity) losses; magnetic (complex permeability) losses; and a combination of both types of losses to investigate the overall impact of the losses on the emergence of negative index bands.
关键词： complex permittivity and permeability,loss compensation,plane wave polarization,material dispersion,negative index bands,Negative refractive index
更新于2025-09-23 15:22:29
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60-GHz 2-D Scanning Multibeam Cavity Backed Patch Array fed by Compact SIW Beam-Forming Network for 5G Applications
摘要： This paper presents a 2x2 multibeam array employing a novel wideband linearly polarized cavity-backed patch antenna for fifth generation (5G) wireless communication technology. The antenna array comprises four layers stacked on top of one another. The proposed antenna element is composed of three substrate layers and excited using a substrate integrated waveguide (SIW) aperture-coupled feed. The antenna element exhibits -10-dB impedance bandwidth of 36.2% from 53 to 76.4 GHz with very flat gain and excellent radiation characteristics. A prototype is fabricated and tested. The compact 2-D scanning multibeam 2x2 antenna array is demonstrated at 60-GHz, where the proposed antenna element is utilized as a radiating element. By employing a novel compact beam forming network (BFN) in the design, the proposed array achieves a size reduction of better than 28% compared to an array fed with conventional BFN, without degradation in the array performance. A wide bandwidth larger than 27 % for |S11|<-10 dB and a peak gain of 12.4 dBi is achieved. The array shows a good symmetrical radiation pattern in the two perpendicular planes. Verified by prototype measurements, the proposed antenna element and multibeam array with features of a compact structure, low cost, wide bandwidth and superior radiation performance, would be practically attractive for 5G applications.
关键词： fifth generation (5G),linear polarization,60 GHz,SIW,beam-forming network,multibeam antenna
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition (iWEM) - Nagoya (2018.8.29-2018.8.31)] 2018 IEEE International Workshop on Electromagnetics:Applications and Student Innovation Competition (iWEM) - Functional Microstrip Array Antenna Integrating Double-Sided MIC's
摘要： In this paper, functional microstrip array antennas are demonstrated. The double-sided MIC is effectively utilized to realize the functions with a simple structure. Dual circular polarization and CP sense switching capability are achieved on a single-layer substrate.
关键词： microstrip array antenna,double-sided MIC,dual-polarization
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Coimbatore (2018.3.1-2018.3.3)] 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Broadband Circularly Polarized U-Slot Antenna for Wireless Application
摘要： The antenna presented in this paper is a broadband circularly polarized U slot antenna. The circularly polarized radiation is achieved in this paper by suspending two separated rectangular strips from the inner edge of ground and using inverted L-shaped central feeding stub. The L-shaped stub is oriented at 90 degree with respect to grounded strips. The impedance bandwidth of the antenna proposed here varies from (4.68 - 6.42 GHz) which is 31.3% and the axial ratio bandwidth (<3 dB) is from (5.15-6.45 GHz) which is 22.4% for WLAN (ranging from 5.15 to 5.85 GHz) and WIMAX (5.8GHz,5.5 GHz) applications. The antenna is left and right hand circularly polarized in Z>0 and Z<0 directions respectively. A wide notch is cut from the ground which enhances the ARBW by 51.35% in comparison to simple square shaped ground. All the results have been simulated successfully.
关键词： circular polarization (CP),axial ratio bandwidth (ARBW),slot antenna,coplanar waveguide (CPW),wireless LAN
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) - Broadband Circularly Polarized Monopole Antenna with an Open loop
摘要： A broadband circularly polarized (CP) monopole antenna with an annular open-loop is presented. By introducing a gap on the loop, the presented antenna features broadband and produces a bidirectional CP radiation. The simulated results show that the proposed antenna has the advantage of broadband CP characteristics in terms of an impedance bandwidth with S11< -10 dB of 96.1% from 2.7 to 7.7 GHz and a 3-dB axial ratio (AR) bandwidth of 81.3% in the frequency range of 2.7 to 6.4 GHz.
关键词： circular polarization,Loop antenna,broadband,monopole antenna
更新于2025-09-23 15:22:29
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High cadence, linear, and circular polarization monitoring of OJ 287
摘要： Aims. We present a multifrequency, dense radio monitoring program of the blazar OJ 287 using the 100-m Effelsberg radio telescope. The program aims to test different binary supermassive black hole (SMBH) scenarios and studying the physical conditions in the central region of this bright blazar. Here, we analyze the evolution in total flux density, linear and circular polarization as a means to study the OJ 287 jet structure and its magnetic field geometry. Methods. We used a recently developed, high-precision data analysis methodology to recover all four Stokes parameters. We measured the total flux density of OJ 287 at nine bands from 2.64 GHz to 43 GHz, the linear polarization parameters at four bands between 2.64 GHz and 10.45 GHz, and the circular polarization at two bands, 4.85 GHz and 8.35 GHz. The mean cadence of our measurements is ten days. Results. Between December 2015 and January 2017 (MJD 57370–57785), OJ 287 showed flaring activity and complex linear and circular polarization behavior. The radio electric vector position angle (EVPA) showed a large clockwise (CW) rotation by ～340? with a mean rate of ?1.04?/day. Based on concurrent very long baseline interferometric (VLBI) polarization data at 15 GHz and 43 GHz, the rotation seems to originate within the jet core at 43 GHz (projected angular size ≤0.15 mas or 0.67 pc at the redshift of the source). Moreover, optical polarization data show a similar monotonic CW rotation with a rate of about ?1.1?/day which is superposed with shorter and faster rotations that exhibit rates of about 7.8?/day, mainly in the CW sense. Conclusions. The flux density and polarization variability of the single dish, VLBI and optical data is consistent with a polarized emission component propagating on a helical trajectory within a bent jet. We constrained the helix arc length to 0.26 pc and radius to ≤0.04 pc as well as the jet bending arc length projected on the plane of the sky to ≤1.9–7.6 pc. A similar bending has been observed also in high angular resolution VLBI images of the OJ 287 jet at its innermost regions. The helical trajectory covers only a part of the jet width, possibly its spine. In addition, our results indicate the presence of a stable polarized emission component. Its EVPA (?10?) is oriented perpendicular to the large scale jet, suggesting dominance of the poloidal magnetic field component. Finally, the EVPA rotation begins simultaneously with an optical flare and hence the two might be physically connected. That optical flare has been suggested to be linked to the interaction of a secondary SMBH with the inner accretion disk or originating in the jet of the primary.
关键词： BL Lacertae objects: individual: OJ 287,galaxies: active,quasars: supermassive black holes,magnetic fields,galaxies: jets,polarization
更新于2025-09-23 15:22:29
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Implications of Distributed Link Polarization Dependent Loss on Bit-Wise Achievable Information Rates for Probabilistically Shaped and Uniform DP 64-QAM
摘要： The statistical behaviours of bit-wise achievable information rates (BW AIRs) and effective signal-to-noise ratios (SNRs) due to polarization dependent loss (PDL) are experimentally characterized for probabilistically shaped and uniform dual-polarization 64-ary quadrature amplitude modulation (DP 64-QAM) with a bit rate of 250 Gb/s. A single-span recirculating loop is used to emulate distributed link PDL. Histograms for the BW AIR and effective SNR following offline signal processing resemble shifted, mirror-image Maxwell probability density functions for both constellations and two different per-loop PDL values. For a transmission distance of 1200 km and a per-loop PDL of 1.3 dB, the outage probabilities for the shaped and uniform constellations are estimated to be 1.1 × 10?3 and 4.4 × 10?1, respectively. Moreover, for an outage probability ≤ 4.0 × 10?3, the increase in transmission distance due to shaping is reduced by 50% compared to that for PDL free transmission.
关键词： Probabilistic shaping,coherent optical fiber transmission systems,polarization dependent loss
更新于2025-09-23 15:22:29
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Perpendicular-Corporate Feed in a Four-Layer Circularly-Polarized Parallel-Plate Slot Array
摘要： This paper presents a design for the perpendicular-corporate feed in a four-layer circularly-polarized parallel-plate slot array antenna. We place a dielectric layer with adequate permittivity in the region between the coupling-aperture and the radiating-slot layers to remove x-shaped cavity walls completely in the radiating part of a conventional planar corporate-feed waveguide slot array antenna. To address fabrication constraints, the dielectric layer consists of PTFE and air. It excites a strong standing wave in the region and so provides 2 × 2-element subarrays with uniform excitation. None of the slot layers are in electrical contact due to air gaps between the slot layers. The four-layer structure with apertures for circular polarization contributes to wideband design for axial ratios because of the eigenmodes in the desired band. We realize an 11.9% bandwidth for axial ratios of less than 3.0 dB as confirmed by measurements in the 60 GHz band. At the design frequency, the measured realized gain is 32.7 dBi with an antenna efficiency of 75.5%.
关键词： slot array,perpendicular-corporate feed,circularly-polarization,parallel plates
更新于2025-09-23 15:22:29
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Diffraction Focal Position and Vector Diffraction Theory for Micro Holographic Storage Systems
摘要： In this study, we proposed a method to determine the optimal focal position for micro-holographic storage systems, using vector diffraction theory; the theory provides exact solutions when the numerical aperture (NA) exceeds 0.6. The best diffraction focus was determined by the position and wavelength corresponding to minimal spherical aberration. The calculated refractive index modulation, polarization illumination, and boundary conditions at the interface of different media were analyzed. From the results of our analysis, we could confirm the size of micrograting as a function of NA and wavelength, based on vector diffraction theory, compared with scalar diffraction theory which defines the micrograting by . To demonstrate our analysis, we adapted an optical alignment method using a Twyman-Green interferometer, and could obtain good agreement between analysis and experimental results.
关键词： microholographic storage system,diffraction focus,vector diffraction theory,scalar diffraction theory,diffraction efficiency,refractive index modulation,interferogram,polarization
更新于2025-09-23 15:22:29
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A Pilot Symbols Aided Adaptive Kalman Filter for Joint Carrier Phase and Polarization Tracking in Coherent Optical System
摘要： A joint compensation scheme based on pilot symbols aiding adaptive Kalman filter (AKF) for phase noise and polarization cross-talk is proposed and investigated via numerical simulation and experimental demonstration. In the proposed scheme, the optimizing parameter Q is adaptively adjusted according to signal parameters or channel conditions. This improvement avoids the drawback of conventional extended Kalman filter (EKF), and its performance is strongly dependent on Q. Another improvement is that the convergence speed of AKF is improved. Pilot quadrature phase shift keyin (QPSK) symbols are inserted into 16 quadrature amplitude modulation (QAM) signals periodically. Besides accelerating convergence speed, the employment of pilot symbols also improves the tracking capability of AKF. The format ratio between pilot symbols and payload symbols is suggested under different system environments, for instance, optical signal-to-noise rate, polarization rotation frequency drift rate, and laser linewidth. With the proposed scheme, it has excellent tolerance to initial parameter Q and dramatically improves the performances in convergence speed, polarization rotation frequency drift rate tracking, and carrier phase recovery. Both the numerical simulation and experimental demonstration achieve convergence improvement for around 40 times than the original AKF. Additionally, the improvements in tracking ability are also demonstrated.
关键词： dynamic polarization rotation,pilot aided adaptive Kalman filter,phase noise,coherent optical communication
更新于2025-09-23 15:22:29