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Design of high gain, broadband resonant cavity antenna with meta-material inspired superstrate
摘要： A broadband high gain planar meta-material based Resonant Cavity Antenna (RCA) operating at C-band is proposed. The RCA is modeled using simple ray tracing method. The unit cell metamaterial consists of Artificial Magnetic Conductor (AMC) and square patch laminated on either side of a lossy commercial dielectric material of dielectric constant 4.4 & thickness 1.6mm, is used as the superstrate to design RCA. Square patch is the capacitive type and that AMC as inductive. Effects of the reflection phase of the substrate decide the high gain of the antenna. A cylindrical dielectric resonator antenna (CDRA) is embedded into the cavity as a feed. The proposed antenna achieves 22.4dBi gain with 2 layers of 4x4 array superstrate with a bandwidth of around 5.1GHz. The full-wave analysis is performed to extract the impedance matching, radiation pattern & gain of the composite RCA. A prototype antenna is fabricated and tested for verification of experimental results which was found to be well correlated. It also shows that the proposed RCA achieves -10dB impedance bandwidth of 72.72% ranging from 4 to 9.1GHz with a high gain around 22.4dBi.
关键词： Cylindrical Dielectric Resonator Antenna (CDRA),Metamaterials (MTM),Resonant Cavity Antenna (RCA)
更新于2025-09-23 15:23:52
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A cavity depth sensitized Rossiter mode formula
摘要： A depth sensitized Rossiter mode expression for compressible resonant cavity ?ows is derived based on simple shear layer and acoustic concepts. The physics-based result is compared to relevant experiment measurements and empirical models and shows reasonable agreement. Though simple, the cavity depth sensitized Rossiter mode estimate demonstrates the connection between shear layer ?ow and cavity acoustics; moreover, the model provides a useful analytically-based validation metric for detailed resonant cavity simulations.
关键词： Vortex sheet,Rossiter mode,Resonant cavity
更新于2025-09-23 15:23:52
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Ideal efficiency of resonant cavity-enhanced perovskite solar cells
摘要： Perovskite solar cells (PSCs) have attracted significant attention in recent years due to the rapid increase in device efficiency (reaching over 25% in 2019), ease of fabrication, and the potential to produce low-cost photovoltaic modules. In this paper we have determined the ideal power conversion efficiency and quantum efficiency of PSCs with the p–i–n device structure, where p is the hole transport layer, i is the perovskite absorber layer, and n is the electron transport layer. The absorption of incident light occurs in a thin perovskite layer, the thickness of which is comparable to the wavelength of absorbed light. We take into account interference effects when the PSC structure is represented by a Fabry–Perot resonator. The optical flux within the absorbing layer is calculated as a function of the spatial coordinate (in the direction of the layer thickness), for a certain wavelength, at the normal incident light. The power quantum efficiency is calculated assuming that the incident light source is a blackbody at the temperature of the Sun, as well as for the AM1.5g standard solar spectrum. The results obtained by using the derived expressions that take into account the interference effects are compared with those obtained by neglecting these effects.
关键词： Resonant cavity,Efficiency,Perovskite,Solar cell
更新于2025-09-23 15:19:57
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Dielectric replica measurement: A new technique for obtaining the complex permittivity of irregularly shaped objects
摘要： Dielectric measurements provide valuable information about the properties of materials, and could be used to classify and identify the source of objects, in fields such as archaeology. Current methods of identification are all partly destructive, so an innovative electromagnetic method developed by the authors, based on resonant cavity perturbation (RCP), provides an attractive, non-destructive alternative. A problem with traditional RCP is that the changes in frequency and Q-factor vary with the object's shape; however we overcome this by creating a replica of the object, from a material whose dielectric properties are known. Then, by combining three separate perturbations with orthogonal field directions, due firstly to the object and then to its replica, we eliminate the shape dependency, and thus determine the object's dielectric constant and loss factor. After developing the theory of this novel DRM technique, we demonstrate the principle using a set of geometric shapes made in both polytetrafluoroethylene (PTFE) and a 3D printed material. Further measurements then enable second-order terms to be included in the model, improving its accuracy. Finally, DRM is shown to be capable of distinguishing two irregularly shaped objects of different materials. Potential applications of DRM include determining the provenance of pottery, glasses and flints, and distinguishing ivory from bone. These would be of interest to customs and environmental agencies, as well as museum curators and archaeologists.
关键词： resonant cavity,3D printing,artefact,network analyser,Dielectric measurement,archaeology,complex permittivity,non-destructive testing
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Investigation of Resonant-Cavity-Enhanced GeSn Photodetectors in Short-Wavelength Infrared Regime
摘要： GeSn with a 10% Sn content for resonant-cavity-enhanced photodetectors (RCE PDs) was grown and the RCE PDs was designed for 2000-nm operation, exhibiting a quantum efficiency up to 91%. This work shows RCE GeSn PDs can be a promising route toward high-response SWIR detection.
关键词： quantum efficiency,Resonant-cavity-enhanced photodetectors,GeSn
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Investigation of Resonant-Cavity-Enhanced GeSn Photodetectors in Short-Wavelength Infrared Regime
摘要： GeSn with a 10% Sn content for resonant-cavity-enhanced photodetectors (RCE PDs) was grown and the RCE PDs was designed for 2000-nm operation, exhibiting a quantum efficiency up to 91%. This work shows RCE GeSn PDs can be a promising route toward high-response SWIR detection.
关键词： Resonant-cavity-enhanced photodetectors,quantum efficiency,GeSn
更新于2025-09-12 10:27:22
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Bose Condensation of Long-Living Direct Excitons in an Off-Resonant Cavity
摘要： We propose a way to increase the lifetime of two-dimensional direct excitons and show the possibility to observe their macroscopically coherent state at temperatures much higher than that of indirect exciton condensation. For a single GaAs quantum well embedded in photonic layered heterostructures with subwavelength period, we predict the exciton radiative decay to be strongly suppressed. Quantum hydrodynamics joined with the Bogoliubov approach are used to study the Berezinskii-Kosterlitz-Thouless crossover in a finite exciton system with intermediate densities. Below the estimated critical temperatures, drastic growth of the correlation length is shown to be accompanied by a manyfold increase of the photoluminescence intensity.
关键词： Bogoliubov approach,Berezinskii-Kosterlitz-Thouless crossover,Bose condensation,direct excitons,quantum hydrodynamics,off-resonant cavity
更新于2025-09-09 09:28:46
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W-band Sparse Imaging System Using Frequency Diverse Cavity-Fed Metasurface Antennas
摘要： We experimentally demonstrate a frequency-diverse, computational imaging system at W-band frequencies utilizing an array of cavity-fed metasurface antennas. Each metasurface antenna consists of a cavity milled from aluminum stock, with an upper plate patterned with a set of radiating slots. As a function of frequency, the metasurface cavities produce a set of spatially diverse radiation patterns that probe the re?ectivity distribution of a scene. The antennas are designed to maximize the measurement diversity and hence imaging capacity of the system. The number and distribution of the radiating slots is optimized by balancing the cavity quality factor (Q) and Fourier space coverage. In the experimental realizations, the radiation patterns from each cavity-fed metasurface antenna is ?rst measured using near-?eld scanning techniques, propagated over the imaging domain, and then stored for use in the image reconstruction step. Comprehensive alignment procedure is implemented to align the measured radiation patterns with regard to the physical position of the cavities. Using a modeling platform, we ?nd excellent agreement between the simulation and experiment, indicating the validity of the calibration and alignment procedures. The scaling of the cavity-fed metasurface antenna represents a key step in the development of alternative high-frequency apertures for imaging and beam-forming applications.
关键词： Metasurface antennas,Resonant Cavity,W-Band,Millimeter waves,Frequency Diverse,Sparse Imaging
更新于2025-09-04 15:30:14
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Direct and photon-assisted tunneling in resonant-cavity quantum-well light-emitting transistors
摘要： Tunneling in a transistor is a critical quantum process toward the next-generation, energy-efficient, high-speed data transfer for both electrical and optical communications. In this work, resonant-cavity quantum-well light-emitting transistors with tunneling collector junctions are designed and fabricated. Three distinctive tunneling mechanisms are clearly identified by the transistor optical output family curves, namely, electron direct tunneling (DT) from collector to base, electron DT from base to collector, and intra-cavity photon-assisted electron tunneling from base to collector. The device operations under both direct and photon-assisted tunneling are explained in detail by the intra-cavity quantum transition of electron-hole pair to photon dynamics. The tunnel junction and the corresponding carrier tunneling injection suggest the possibility of utilizing tunneling to achieve high-speed optoelectronics operations.
关键词： photon-assisted tunneling,optoelectronics,quantum-well,resonant-cavity,light-emitting,transistor,tunneling
更新于2025-09-04 15:30:14