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Ripple Suppression in Broadband Microwave Photonic Phase Shifter Frequency Response
摘要： This paper presents a detailed investigation on the cause of ripples in the frequency response of a microwave photonic phase shifter implemented using a 90° hybrid coupler. It was found that an unwanted radio frequency (RF) modulation sideband is generated at the modulator output due to the 90° hybrid coupler amplitude and phase imbalance. This resulted in phase shifter output RF signal amplitude variation and phase deviation. Experimental results demonstrated that incorporating an optical filter in the phase shifter structure can reduce the amplitude variation and phase deviation from 4.2 dB to 2.2 dB and from ±12° to ±3.8°, respectively, over a wide frequency range. A comparison of the loss and the dynamic range of the microwave photonic phase shifter implemented using a 90° hybrid coupler with a conventional fiber optic link is also presented.
关键词： phase shifters,microwave photonics,optical signal processing
更新于2025-09-23 15:23:52
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Microwave Photonic Devices Based on Liquid Crystal on Silicon Technology
摘要： This paper reviews the recent developments in microwave photonic devices based on liquid crystal on silicon (LCOS) technology. The operation principle, functions and important specifications of an LCOS based optical processor are described. Three microwave photonic devices, which are microwave photonic notch filters, phase shifters and couplers, reported in the past five years are focused on in this paper. In addition, a new multi-function signal processing structure based on amplitude and phase control functions in conjunction with a power splitting function in a commercial LCOS based optical processor is presented. It has the ability to realize multiple time-shifting operations and multiple frequency-independent phase shifting operations at the same time and control multiple RF signal amplitudes, in a single unit. The results for the new multi-function microwave photonic signal processor demonstrate multiple tunable true time delay and phase shifting operations with less than 3 dB amplitude variation over a very wide frequency range of 10 to 40 GHz.
关键词： phase shifters,optical signal processing,filters,true time delays,microwave photonics
更新于2025-09-23 15:22:29
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Gradient Projection-Based Alternating Minimization Algorithm for Designing Hybrid Beamforming in Millimeter-Wave MIMO Systems
摘要： This study considers the use of alternating minimization (AltMin) framework as the main design principle in determining the optimal weights of hybrid digital and analog beamforming in millimeter-wave massive multiple-input multiple-output systems. However, such framework experiences analog beamformer design problem because analog beamformers are normally constructed using phase shifters (PSs), which result in non-convex constraints, and known solutions suffer from high computational complexity. We address this issue by proposing a simple yet efficient gradient projection (GP)-based AltMin (GP-AltMin) algorithm for hybrid beamforming design problems. In addition, when quantized PSs are adopted, we propose non-uniform PSs on the basis of the Lloyd-Max algorithm for minimizing the performance loss caused by quantization. Simulation results demonstrate that the proposed GP-AltMin algorithm not only has lower complexity but can also achieve spectral efficiency, which is comparable with or higher than those of state-of-the-art algorithms that use unquantized and low-resolution PSs.
关键词： gradient projection,massive MIMO,Beamforming,finite resolution phase shifters,millimeter-wave
更新于2025-09-23 15:21:21
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Two-Phase Resonant Converter to Drive High-Power LED Lamps
摘要： This paper presents the design and modeling of a two-phase resonant converter that drives a LED lamp with a high-frequency pulsed current free of instabilities and flicker effect, fulfilling the recommendations of the IEEE PAR 1789-2015, so that it enables visible light-based communication at a 10 kB/s bit rate. The dynamic study of the converter takes into consideration the effect of the reflected impedance of the output filter on the AC side. In order to evaluate the dynamic response of the converter, a Spice model is defined. A 120 W prototype intended for street lighting applications has been built to validate the analysis and modeling.
关键词： phase shifters,lighting control,LED lamps,closed-loop systems,small-signal modeling,light sources
更新于2025-09-19 17:13:59
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[IEEE 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Granada, Spain (2019.9.9-2019.9.13)] 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Azimuthally Magnetized Circular Ferrite-Dielectric Waveguide: Impact of the Material and Geometry Parameters on the Cut-off Frequencies for the Normal $TE_{0\mathrm{n}}$ Modes
摘要： A method for computation of the cut-off frequencies (the critical radius) of the circular waveguide, containing a co-axial dielectric cylinder and a ferrite toroid of azimuthal magnetization that supports normal modes, is elaborated. It uses certain roots of the characteristic equation of transmission line, derived before in terms of complex Kummer and Tricomi confluent hypergeometric, and real ordinary or modified zeroth and first order Bessel functions. Their values are counted up, employing specially developed iterative technique. The dependence of cut-off frequencies on the dimension of dielectric filling and the magnitude of its relative permittivity is studied in detail, provided the latter is less than that of the ferrite one. The results are presented numerically in normalized form for the the 01TE permeability tensor, describing the anisotropic medium, is small.
关键词： boundary-value problems,ferrite phase shifters,circular waveguides,numerical techniques.
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - A Compact Butler Matrix Design Based on Metallic Nanowire Filled Membrane Technology and Tunable Phase Shifter at 160 GHz
摘要： This paper presents the design of a planar miniaturized 4x4 Butler matrix, with implementation of 4 tunable 135° delay line phase shifters for a 160 GHz application. The Butler matrix and phase shifters are both realized with a metallic nanowire filled slow-wave alumina membrane microstrip line to miniaturize the size. Tunability is achieved by filling in a microwave liquid crystal. Comparing with commonly used corporate feed network, the simulation results show such a Butler matrix with 135°-phase shifters has less insertion loss and reduced size.
关键词： 160 GHz,slow-wave alumina membrane,Butler matrix,metallic nanowire,phase shifters,liquid crystal
更新于2025-09-16 10:30:52
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Configurable Perforated Air-Filled Substrate Integrated Waveguide (AFSIW) For Generic High-Performance Systems on Substrate
摘要： In this article, the patent pending configurable perforated air-filled substrate integrated waveguide (PAFSIW) is presented. First, a theoretical and experimental study of the proposed PAFSIW topology is introduced. Specifically, it is demonstrated that a low-cost Hi-Tg FR4 PAFSIW transmission line can handle over 190 W (up to 1340 W, determined from extrapolation of the experimental results) of continuous wave (CW) power at 20 GHz with an enhanced thermal dissipation compared with its AFISW counterpart. Then, configurable phase shifters, resonators, and filters based on the PAFSIW transmission line sections are introduced. Those components are fabricated using the conventional printed circuit board (PCB) and the through-hole mounting (THM) process to demonstrate the PAFSIW versatility and fabrication-tolerance robustness. The proposed PAFSIW extends the capabilities of the high-performance AFSIW technological platform as it provides genericity, manufacturing process robustness, and an alternative to improve thermal dissipation. The authors expect its implementation in highly configurable microwave- and millimeter-wave circuits for future generic systems on substrate.
关键词： systems on substrate,filters,power-handling,cavities,Air-filled substrate integrated waveguides (AFSIWs),transmission lines,resonators,configurability,phase shifters
更新于2025-09-11 14:15:04
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[IEEE 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Granada, Spain (2019.9.9-2019.9.13)] 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Azimuthally Magnetized Circular Ferrite-Dielectric Waveguide: Condition for Phase Shifter Operation
摘要： The condition under which a circular waveguide, loaded with a co-axial dielectric cylinder and a latching ferrite toroid, magnetized azimuthally, exhibits properties of a nonreciprocal digital phase shifter for the 01TE mode, is derived. A numerical approach is developed and applied to study the dependence of the width of the area in which the structure regarded produces differential phase shift on its material and geometry parameters. It makes use of a specific set of roots of the characteristic equation of configuration, deduced earlier by complex Kummer and Tricomi or by Tricomi and its complex conjugate confluent hypergeometric functions, and by real zeroth and first order Bessel ones, and by the real positive ±4L numbers, linked with another set of roots of the equation said. Results are given for a chosen value of the off-diagonal ferrite permeability tensor element and a changing dielectric cylinder to transmission line radius ratio. It is accepted that the relative permittivities of the two media are the same.
关键词： numerical techniques,boundary-value problems,ferrite phase shifters,circular waveguides
更新于2025-09-11 14:15:04
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Null Technique for Precision RF Phase Shift Measurements
摘要： A dual channel IF substitution null system is developed for precision phase shift measurements and standards in frequency ranges of 1 MHz to 1 GHz. A particular programmable IF phase shifter equipped with a calibrated phase monitor is used as a phase reference standard. High sensitivity nature of the null technique provides accurate measurements to the DUT even with large attenuation. Measurement resolutions of 0.002 deg., 0.006 deg., and 0.023 deg. were obtained for DUT with attenuation of 20 dB, 40 dB, and 60 dB, respectively, at 1 GHz.
关键词： Phase measurement,uncertainty,radio frequency,precision measurements,attenuation measurement,phase shifters
更新于2025-09-10 09:29:36
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Theoretical Minimum of Phase Shift Error of Switchable-channel Phase Shifters on Left-handed and Right-handed Transmission Lines
摘要： The minimum phase shift error of switchable-channel phase shifters on right-handed (RH) and left-handed (LH) transmission lines (TLs) is theoretically evaluated by using models of the ideal RH and LH TLs. Difference in frequency characteristics of the ideal TLs and their artificial counterparts consisting of lumped inductors and capacitors is discussed.
关键词： phase shifters,differential phase shift,phase shift error
更新于2025-09-09 09:28:46