The Experts below are selected from a list of 396 Experts worldwide ranked by ideXlab platform

Bingda Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Multi-Rate Real-Time Simulation Method Based on the Norton Equivalent
    Energies, 2020
    Co-Authors: Junjie Zhu, Bingda Zhang
    Abstract:

    For the problem of poor accuracy of the existing multi-rate simulation methods, this paper proposes a multi-rate real-time simulation method based on the Norton Equivalent, compared with multi-rate simulation method based on the ideal source Equivalent. After the Norton equivalence of the fast subsystem and the slow subsystem are established, they are solved simultaneously at the junction nodes. In order to reduce the amount of the simulation calculation, the Norton Equivalent Circuit is obtained by incremental calculation. The data interaction between the fast subsystem and the slow subsystem is realized by extrapolation method. For ensuring the real-time performance of the simulation, the method of the slow subsystem calculates ahead of the fast subsystem is given for the slow subsystem with a large amount of calculation. Finally, the AC/DC hybrid power system was simulated on the real-time simulation platform (FPGA-based Real-Time Digital Solver, FRTDS), and the simulation results were compared with the single-rate simulation, which verified the correctness and accuracy of the proposed method.

  • Multi-Rate Real-Time Simulation Method Based on the Norton Equivalent
    2020
    Co-Authors: Junjie Zhu, Bingda Zhang
    Abstract:

    For the problem of poor accuracy of the existing multi-rate simulation methods, this paper proposes a multi rate real-time simulation method based on the Norton Equivalent, compared with multi-rate simulation method based on the ideal source Equivalent. After the Norton equivalence of the fast subsystem and the slow subsystem, they are obtained simultaneously at the junction nodes. In order to reduce the amount of simulation calculation, the Norton Equivalent Circuit is obtained by incremental calculation. The data interface between the fast subsystem and the slow subsystem is realized by extrapolation method. For ensuring the real-time performance of the simulation, the method that the slow subsystem calculates ahead of the fast subsystem is given for the slow subsystem with a large amount of calculation. Finally, the AC/DC hybrid power system was simulated on the real-time simulation platform (FRTDS), and the simulation results were compared with the single-rate simulation, which verified the correctness and accuracy of the method.

Junjie Zhu - One of the best experts on this subject based on the ideXlab platform.

  • Multi-Rate Real-Time Simulation Method Based on the Norton Equivalent
    Energies, 2020
    Co-Authors: Junjie Zhu, Bingda Zhang
    Abstract:

    For the problem of poor accuracy of the existing multi-rate simulation methods, this paper proposes a multi-rate real-time simulation method based on the Norton Equivalent, compared with multi-rate simulation method based on the ideal source Equivalent. After the Norton equivalence of the fast subsystem and the slow subsystem are established, they are solved simultaneously at the junction nodes. In order to reduce the amount of the simulation calculation, the Norton Equivalent Circuit is obtained by incremental calculation. The data interaction between the fast subsystem and the slow subsystem is realized by extrapolation method. For ensuring the real-time performance of the simulation, the method of the slow subsystem calculates ahead of the fast subsystem is given for the slow subsystem with a large amount of calculation. Finally, the AC/DC hybrid power system was simulated on the real-time simulation platform (FPGA-based Real-Time Digital Solver, FRTDS), and the simulation results were compared with the single-rate simulation, which verified the correctness and accuracy of the proposed method.

  • Multi-Rate Real-Time Simulation Method Based on the Norton Equivalent
    2020
    Co-Authors: Junjie Zhu, Bingda Zhang
    Abstract:

    For the problem of poor accuracy of the existing multi-rate simulation methods, this paper proposes a multi rate real-time simulation method based on the Norton Equivalent, compared with multi-rate simulation method based on the ideal source Equivalent. After the Norton equivalence of the fast subsystem and the slow subsystem, they are obtained simultaneously at the junction nodes. In order to reduce the amount of simulation calculation, the Norton Equivalent Circuit is obtained by incremental calculation. The data interface between the fast subsystem and the slow subsystem is realized by extrapolation method. For ensuring the real-time performance of the simulation, the method that the slow subsystem calculates ahead of the fast subsystem is given for the slow subsystem with a large amount of calculation. Finally, the AC/DC hybrid power system was simulated on the real-time simulation platform (FRTDS), and the simulation results were compared with the single-rate simulation, which verified the correctness and accuracy of the method.

Alessandro Garufo - One of the best experts on this subject based on the ideXlab platform.

  • Norton Equivalent Circuit for pulsed photoconductive antennas part i theoretical model
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Nuria Llombart, A Neto
    Abstract:

    A novel Equivalent Circuit for pulsed photoconductive sources is introduced for describing the coupling between the photoconductive gap and the antenna. The proposed Circuit effectively describes the mechanism of feeding the antenna by the semiconductor when this latter is illuminated by a laser operating in a pulsed mode. Starting from the classical continuity equation, which models the free carriers’ density with respect to the laser power pump and the semiconductor features, a Norton Equivalent Circuit in the frequency domain is derived. According to the Norton theorem, the Equivalent source representation is decoupled from the antenna. In particular, for photoconductive antennas (PCAs), the Norton Circuit takes into account of the electrical and optical properties of the semiconductor material, the features of the laser excitation, as well as the geometrical dimensions of the gap. The presence of the electrodes around the gap is part of the antenna and, therefore, it is taken into account in the antenna impedance. The proposed Circuit allows the analysis of the coupling between the photoconductive source and the antenna, providing a tool to analyze and design PCAs.

  • Norton Equivalent Circuit for Pulsed Photoconductive Antennas–Part I: Theoretical Model
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Nuria Llombart, Andrea Neto
    Abstract:

    A novel Equivalent Circuit for pulsed photoconductive sources is introduced for describing the coupling between the photoconductive gap and the antenna. The proposed Circuit effectively describes the mechanism of feeding the antenna by the semiconductor when this latter is illuminated by a laser operating in a pulsed mode. Starting from the classical continuity equation, which models the free carriers’ density with respect to the laser power pump and the semiconductor features, a Norton Equivalent Circuit in the frequency domain is derived. According to the Norton theorem, the Equivalent source representation is decoupled from the antenna. In particular, for photoconductive antennas (PCAs), the Norton Circuit takes into account of the electrical and optical properties of the semiconductor material, the features of the laser excitation, as well as the geometrical dimensions of the gap. The presence of the electrodes around the gap is part of the antenna and, therefore, it is taken into account in the antenna impedance. The proposed Circuit allows the analysis of the coupling between the photoconductive source and the antenna, providing a tool to analyze and design PCAs.

  • Norton Equivalent Circuit for pulsed photoconductive antennas part ii experimental validation
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Joshua R. Freeman, David R. Bacon, Nuria Llombart, Edmund H. Linfield, Alexander Giles Davies, A Neto
    Abstract:

    This second part of two papers’ sequence presents the experimental validation of the Norton Equivalent Circuit model for pulsed photoconductive antennas (PCAs) provided in the first paper of the sequence. To this goal, different prototypes of photoconductive antenna sources have been manufactured and assembled. The average powers radiated and their pertinent energy spectral densities have been measured. In order to obtain a validation of the original Equivalent Circuit proposed, an auxiliary electromagnetic analysis of the complete setup, including the quasi-optical (QO) link for the signals from the antenna feeds to the detectors had to be developed. By using the combined theoretical model (Circuit and quasi-optics), an excellent agreement is achieved between the measured power and the power estimated. This agreement fully validates the Circuit model, which can now be used to design new PCAs, including optical and electrical features of the semiconductor materials, as well as the details of the antenna gaps and the purely QO components.

  • Norton Equivalent Circuit for Pulsed Photoconductive Antennas—Part II: Experimental Validation
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Joshua R. Freeman, David R. Bacon, Nuria Llombart, Edmund H. Linfield, Alexander Giles Davies, Andrea Neto
    Abstract:

    This second part of two papers’ sequence presents the experimental validation of the Norton Equivalent Circuit model for pulsed photoconductive antennas (PCAs) provided in the first paper of the sequence. To this goal, different prototypes of photoconductive antenna sources have been manufactured and assembled. The average powers radiated and their pertinent energy spectral densities have been measured. In order to obtain a validation of the original Equivalent Circuit proposed, an auxiliary electromagnetic analysis of the complete setup, including the quasi-optical (QO) link for the signals from the antenna feeds to the detectors had to be developed. By using the combined theoretical model (Circuit and quasi-optics), an excellent agreement is achieved between the measured power and the power estimated. This agreement fully validates the Circuit model, which can now be used to design new PCAs, including optical and electrical features of the semiconductor materials, as well as the details of the antenna gaps and the purely QO components.

  • Towards the Engineering of Pulsed Photoconductive Antennas
    2017
    Co-Authors: Alessandro Garufo
    Abstract:

    In recent years, Terahertz technology has attracted the interest of researchers for its potential applications in a variety of domains. In particular, THz sensing has found application in security screening, medical imaging, spectroscopy, and non-destructive testing. The emergence of all these applications has been driven by the availability of photoconductive antennas, which have made available bandwidth in the THz spectrum at relatively low cost, thanks to several breakthroughs in photonics, and semiconductor technology. Photoconductive antennas are optoelectronic electromagnetic sources that resort to optically pumped semiconductor materials. Such devices exploit the photoconductivity phenomenon to generate and radiate power over a broadband up to the THz frequencies. However, nowadays the use of photoconductive antennas are confined to niche short-range applications, because of the bottleneck of the low power emitted. Early in this research work, it was understood that such bottleneck came from the fact that there was not a clear description about the coupling between the photocondcutive source and the antenna. For this reason, this work has been focused to develop a Thevenin or Norton Equivalent Circuit for the photoconductor generators of photoconductive antennas. A Norton Equivalent Circuit for pulsed photoconductive antennas has been derived, starting by the electrodynamic model of the photogeneration of free carriers in laser pumped semiconductor material. Such Equivalent Circuit allows to maximize the radiated power as function of the geometry of the gap, the properties of the semiconductor material, and the features of the laser pump, providing a clear description of the coupling between the photoconductor generator and the antenna over the operative bandwidth. An electromagnetic model of the quasi-optical (source-to-detector) channel, typically used for measuring power and spectrum radiated by photoconductive antennas, has been proposed. Such model jointly with the developed Norton Equivalent Circuit allows a complete characterization of the power budget from the source to the detector. Providing for the first time a complete description about the dispersion introduced by the quasi-optical channel on the energy spectrum radiated by photoconductive antennas. The entire proposed model (Equivalent Circuit and channel) has been validated by spectrum and power measurements of photoconductive antenna prototypes. The proposed Equivalent Circuit and the electromagnetic model of the quasi-optical channel provide a powerful engineering tool to design photoconductive antennas, opening the way for more standard engineering optimization of wide band laser pumped sources, resorting to the vast heritage of wide band microwave engineering tools that have been developed mostly for analyzing detectors in radiometric domains. The radiation performances of logarithmic spiral antennas as feed of dense dielectric lenses has been intensively analyzed. The results of the investigation have demonstrated the presence of the leaky wave radiation, when the spiral antenna are printed at the air dielectric interface, leading to a design of a logarithmic spiral antenna lens antenna, which provides an high aperture efficiency over a decade frequency bandwidth. However, only using extremely thin substrate allows to feed this design with a planar feeding system without limiting the bandwidth. A new design of a logarithmic spiral lens antenna has been proposed for relaxing such limitation, introducing a small air gap between the spiral feed and the bottom lens interface, which enhances the leaky wave radiation. Such new design, coupled with a synthesized elliptical lens, achieves directive patterns without sidelobes over a decade frequency bandwidth. Moreover, the new spiral design can be used also as feed of a hemispherical lens with low extension height, when the dispersion of the radiated pulses has to be minimized. A novel design for photoconductive sources has been proposed, aiming to increase dramatically the radiated power with respect to the current photoconductive antennas. The new source is based on the well established concept in the microwave community of connected array. Thanks to the intrinsic wide band behavior of the connected array, the proposed solution is able to radiate efficiently the wide band energy spectrum generated by the photoconductive source. Such design is suitable to be employed also as receiver of ultra-wide bandwidth radiation, increasing the sensitivity with respect to the current photoconductive receivers. In order to implement the design of the photoconductive connected array, an ad-hoc biasing network has been proposed, in order to properly bias all the array cells, preserving the connected structure of the elements. Moreover, a design of an optical system has been proposed, in order to optically excite all the elements of the photoconductive array coherently. Using the proposed Norton Equivalent Circuit for photoconductive generator, a photoconductive connected array generating an average power of 2.35mW over a bandwidth from 0.1THz − 0.4THz has been designed. A demonstrator of the proposed photoconductive source design is going to be realized, and a complete characterization of the prototype will be performed by means of power and spectrum measurements, proving the validity of the concept.

Andrea Neto - One of the best experts on this subject based on the ideXlab platform.

  • Norton Equivalent Circuit for Pulsed Photoconductive Antennas–Part I: Theoretical Model
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Nuria Llombart, Andrea Neto
    Abstract:

    A novel Equivalent Circuit for pulsed photoconductive sources is introduced for describing the coupling between the photoconductive gap and the antenna. The proposed Circuit effectively describes the mechanism of feeding the antenna by the semiconductor when this latter is illuminated by a laser operating in a pulsed mode. Starting from the classical continuity equation, which models the free carriers’ density with respect to the laser power pump and the semiconductor features, a Norton Equivalent Circuit in the frequency domain is derived. According to the Norton theorem, the Equivalent source representation is decoupled from the antenna. In particular, for photoconductive antennas (PCAs), the Norton Circuit takes into account of the electrical and optical properties of the semiconductor material, the features of the laser excitation, as well as the geometrical dimensions of the gap. The presence of the electrodes around the gap is part of the antenna and, therefore, it is taken into account in the antenna impedance. The proposed Circuit allows the analysis of the coupling between the photoconductive source and the antenna, providing a tool to analyze and design PCAs.

  • Norton Equivalent Circuit for Pulsed Photoconductive Antennas—Part II: Experimental Validation
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Joshua R. Freeman, David R. Bacon, Nuria Llombart, Edmund H. Linfield, Alexander Giles Davies, Andrea Neto
    Abstract:

    This second part of two papers’ sequence presents the experimental validation of the Norton Equivalent Circuit model for pulsed photoconductive antennas (PCAs) provided in the first paper of the sequence. To this goal, different prototypes of photoconductive antenna sources have been manufactured and assembled. The average powers radiated and their pertinent energy spectral densities have been measured. In order to obtain a validation of the original Equivalent Circuit proposed, an auxiliary electromagnetic analysis of the complete setup, including the quasi-optical (QO) link for the signals from the antenna feeds to the detectors had to be developed. By using the combined theoretical model (Circuit and quasi-optics), an excellent agreement is achieved between the measured power and the power estimated. This agreement fully validates the Circuit model, which can now be used to design new PCAs, including optical and electrical features of the semiconductor materials, as well as the details of the antenna gaps and the purely QO components.

  • Analysis of photoconductive antenna power radiation by Norton Equivalent Circuit
    2017 47th European Microwave Conference (EuMC), 2017
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Nuria Llombart Juan, Andrea Neto, Ioan E. Lager
    Abstract:

    A novel Norton Equivalent Circuit model for characterizing the photoconductive feed of photoconductive antennas is introduced. It incorporates the physics of the photoconductive antenna's excitation by accounting for: (i) the electrical properties of the photoconductive material; (ii) the features of the optical power excitation; (iii) the geometrical dimensions of the gap between the electrodes that couple the antenna to the photoconductive material. The model is applicable to describing the antenna feeding mechanism for the photoconductors being illuminated by means of lasers operating in both pulsed and continuous modes. The proposed model is validated by comparing the power estimated by it with power measurements of different photoconductive antennas. The advocated solution is conducive to analyzing and designing photoconductive antennas. In particular, it is expected to be at the core of antenna optimization tools for maximizing the Terahertz (THz) power radiation, this making it an important enabler for designing THz time-domain systems.

Giorgio Carluccio - One of the best experts on this subject based on the ideXlab platform.

  • Norton Equivalent Circuit for pulsed photoconductive antennas part i theoretical model
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Nuria Llombart, A Neto
    Abstract:

    A novel Equivalent Circuit for pulsed photoconductive sources is introduced for describing the coupling between the photoconductive gap and the antenna. The proposed Circuit effectively describes the mechanism of feeding the antenna by the semiconductor when this latter is illuminated by a laser operating in a pulsed mode. Starting from the classical continuity equation, which models the free carriers’ density with respect to the laser power pump and the semiconductor features, a Norton Equivalent Circuit in the frequency domain is derived. According to the Norton theorem, the Equivalent source representation is decoupled from the antenna. In particular, for photoconductive antennas (PCAs), the Norton Circuit takes into account of the electrical and optical properties of the semiconductor material, the features of the laser excitation, as well as the geometrical dimensions of the gap. The presence of the electrodes around the gap is part of the antenna and, therefore, it is taken into account in the antenna impedance. The proposed Circuit allows the analysis of the coupling between the photoconductive source and the antenna, providing a tool to analyze and design PCAs.

  • Norton Equivalent Circuit for Pulsed Photoconductive Antennas–Part I: Theoretical Model
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Nuria Llombart, Andrea Neto
    Abstract:

    A novel Equivalent Circuit for pulsed photoconductive sources is introduced for describing the coupling between the photoconductive gap and the antenna. The proposed Circuit effectively describes the mechanism of feeding the antenna by the semiconductor when this latter is illuminated by a laser operating in a pulsed mode. Starting from the classical continuity equation, which models the free carriers’ density with respect to the laser power pump and the semiconductor features, a Norton Equivalent Circuit in the frequency domain is derived. According to the Norton theorem, the Equivalent source representation is decoupled from the antenna. In particular, for photoconductive antennas (PCAs), the Norton Circuit takes into account of the electrical and optical properties of the semiconductor material, the features of the laser excitation, as well as the geometrical dimensions of the gap. The presence of the electrodes around the gap is part of the antenna and, therefore, it is taken into account in the antenna impedance. The proposed Circuit allows the analysis of the coupling between the photoconductive source and the antenna, providing a tool to analyze and design PCAs.

  • Norton Equivalent Circuit for pulsed photoconductive antennas part ii experimental validation
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Joshua R. Freeman, David R. Bacon, Nuria Llombart, Edmund H. Linfield, Alexander Giles Davies, A Neto
    Abstract:

    This second part of two papers’ sequence presents the experimental validation of the Norton Equivalent Circuit model for pulsed photoconductive antennas (PCAs) provided in the first paper of the sequence. To this goal, different prototypes of photoconductive antenna sources have been manufactured and assembled. The average powers radiated and their pertinent energy spectral densities have been measured. In order to obtain a validation of the original Equivalent Circuit proposed, an auxiliary electromagnetic analysis of the complete setup, including the quasi-optical (QO) link for the signals from the antenna feeds to the detectors had to be developed. By using the combined theoretical model (Circuit and quasi-optics), an excellent agreement is achieved between the measured power and the power estimated. This agreement fully validates the Circuit model, which can now be used to design new PCAs, including optical and electrical features of the semiconductor materials, as well as the details of the antenna gaps and the purely QO components.

  • Norton Equivalent Circuit for Pulsed Photoconductive Antennas—Part II: Experimental Validation
    IEEE Transactions on Antennas and Propagation, 2018
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Joshua R. Freeman, David R. Bacon, Nuria Llombart, Edmund H. Linfield, Alexander Giles Davies, Andrea Neto
    Abstract:

    This second part of two papers’ sequence presents the experimental validation of the Norton Equivalent Circuit model for pulsed photoconductive antennas (PCAs) provided in the first paper of the sequence. To this goal, different prototypes of photoconductive antenna sources have been manufactured and assembled. The average powers radiated and their pertinent energy spectral densities have been measured. In order to obtain a validation of the original Equivalent Circuit proposed, an auxiliary electromagnetic analysis of the complete setup, including the quasi-optical (QO) link for the signals from the antenna feeds to the detectors had to be developed. By using the combined theoretical model (Circuit and quasi-optics), an excellent agreement is achieved between the measured power and the power estimated. This agreement fully validates the Circuit model, which can now be used to design new PCAs, including optical and electrical features of the semiconductor materials, as well as the details of the antenna gaps and the purely QO components.

  • Analysis of photoconductive antenna power radiation by Norton Equivalent Circuit
    2017 47th European Microwave Conference (EuMC), 2017
    Co-Authors: Alessandro Garufo, Giorgio Carluccio, Nuria Llombart Juan, Andrea Neto, Ioan E. Lager
    Abstract:

    A novel Norton Equivalent Circuit model for characterizing the photoconductive feed of photoconductive antennas is introduced. It incorporates the physics of the photoconductive antenna's excitation by accounting for: (i) the electrical properties of the photoconductive material; (ii) the features of the optical power excitation; (iii) the geometrical dimensions of the gap between the electrodes that couple the antenna to the photoconductive material. The model is applicable to describing the antenna feeding mechanism for the photoconductors being illuminated by means of lasers operating in both pulsed and continuous modes. The proposed model is validated by comparing the power estimated by it with power measurements of different photoconductive antennas. The advocated solution is conducive to analyzing and designing photoconductive antennas. In particular, it is expected to be at the core of antenna optimization tools for maximizing the Terahertz (THz) power radiation, this making it an important enabler for designing THz time-domain systems.