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Isolated multiple port DC/DC converters, such as the Multiple Active Bridge (MAB) converter, have many recent applications, such as interconnection between grids, isolated uninterruptible power sources (UPSs) and electric vehicle chargers. MAB converter is an attractive solution from the point of view of the hardware because of its symmetry and its capability to be extended to any number of bridges with a moderate number of components. However, the main challenge of this converter is the control method in order to achieve independent control between the different ports and to minimize recirculating currents. For that reason, three‐port power converters have been already investigated, but many improvements can be done for a larger number of ports. This paper proposes to use a Fourier decomposition for the main power signals to separate their real and imaginary parts. As the signals work at the switching frequency, this decomposition is developed with analog electronics. Based on that, a general control method for regulating the power at the different ports is presented using the first harmonic component, which delivers most of the power. In this proposal, two nested control loops ensure accuracy for the DC power flow. Simulation and experimental results validate the proposal. [ABSTRACT FROM AUTHOR]

Abstract Isolated multiple port DC/DC converters, such as the Multiple Active Bridge (MAB) converter, have many recent applications, such as interconnection between grids, isolated uninterruptible power sources (UPSs) and electric vehicle chargers. MAB converter is an attractive solution from the point of view of the hardware because of its symmetry and its capability to be extended to any number of bridges with a moderate number of components. However, the main challenge of this converter is the control method in order to achieve independent control between the different ports and to minimize recirculating currents. For that reason, three‐port power converters have been already investigated, but many improvements can be done for a larger number of ports. This paper proposes to use a Fourier decomposition for the main power signals to separate their real and imaginary parts. As the signals work at the switching frequency, this decomposition is developed with analog electronics. Based on that, a general control method for regulating the power at the different ports is presented using the first harmonic component, which delivers most of the power. In this proposal, two nested control loops ensure accuracy for the DC power flow. Simulation and experimental results validate the proposal.

Abstract High‐gain converters play a vital role in all industrial applications such as automobiles, motor drives, renewable energy systems, and railway transportation sectors. The conventional converters have low gain owing to high‐voltage stress on active MOSFET, diode and low efficiency related with high operating pulse ratio. To overcome the limitations associated with the conventional converters, this study proposes a non‐isolated configuration of multiport quasi‐resonant converter (MP‐QRC) with high gain. The proposed MP‐QRC has the merits of high‐voltage gain, reduced number of components, minimum conduction losses, realization of soft switching in the devices and improved reliability. Moreover, the proposed converter is scalable and can serve as a good candidate in microgrid environment where the integration of more than one input is essential. In this paper, first a comprehensive analysis of various operation modes and design constraints are presented. Further, the study is supported with a reliability evaluation of proposed converter based on component failure. Also, the futuristic behaviour of MP‐QRC under continuous conduction mode as a function of operational and environmental variables is investigated to ascertain the reliability. The steady‐state operation of the converter is demonstrated for off‐board electric vehilce (EV) charging using MATLAB/SIMULINK and experiments performed on a 300‐W test rig.

Abstract Integration of photovoltaic panels (PV) with electric vehicle (EV) charging stations could reduce the grid impact and carbon footprint from the extensive fast and ultra‐fast charging. This paper introduces a decoupled quad‐active‐bridge converter (QAB) with multi‐directional power flow capability, which can integrate PV, energy storage (ES), grid, and EV in a charging station and rule the power among them. As the number of ports increases in the multiple‐active‐bridge converter, the complexity of control increases exponentially because of power decoupling. For the QAB, by tuning one port in series with LC units, the decoupling is achieved between the other three ports, reducing the control difficulty significantly. Further, the resonance decoupling method is extended to the n‐port converter. For different power flows, the system automatically switches between different resonance modes to form higher‐efficiency power flow channels. Three operating modes with decoupled closed‐loop control methods have been constructed for the QAB to be suitable for future charging stations: (1) Charging mode: PV, ES, and grid coordinate with each other to provide incessant and stable charging for EV. (2) Electricity sales mode: Gird is supplied by PV, ES, and EV flexibly. (3) Under no load, PV power is stored locally. Experimental waveforms were presented by a 1‐kW prototype, verifying the effectiveness of power decoupling and the feasibility of the three operating modes.

High‐gain converters play a vital role in all industrial applications such as automobiles, motor drives, renewable energy systems, and railway transportation sectors. The conventional converters have low gain owing to high‐voltage stress on active MOSFET, diode and low efficiency related with high operating pulse ratio. To overcome the limitations associated with the conventional converters, this study proposes a non‐isolated configuration of multiport quasi‐resonant converter (MP‐QRC) with high gain. The proposed MP‐QRC has the merits of high‐voltage gain, reduced number of components, minimum conduction losses, realization of soft switching in the devices and improved reliability. Moreover, the proposed converter is scalable and can serve as a good candidate in microgrid environment where the integration of more than one input is essential. In this paper, first a comprehensive analysis of various operation modes and design constraints are presented. Further, the study is supported with a reliability evaluation of proposed converter based on component failure. Also, the futuristic behaviour of MP‐QRC under continuous conduction mode as a function of operational and environmental variables is investigated to ascertain the reliability. The steady‐state operation of the converter is demonstrated for off‐board electric vehilce (EV) charging using MATLAB/SIMULINK and experiments performed on a 300‐W test rig. [ABSTRACT FROM AUTHOR]

This research looks at microwave devices, specifically, patch antenna along with electromagnetic spectrum, shape, mechanism, analytical methods, simulation tools, and feeding procedures. Patch antennas are distinguished by their rectangular form, with a patch on one side and a ground plane on the other. Patch antennas work by exciting electromagnetic waves inside the patch, which are subsequently transmitted into the surrounding environment. The report also outlines numerous ways for evaluating the performance of microstrip patch antennas. The electromagnetic characteristics of the antenna are analyzed using the transmission line model, cavity model, and multiport network model (MNM). The integral equations that regulate the behavior of the antenna are solved using the method of moments (MoM) and the finite element method (FEM). The spectral domain technique (SDT) is used to analyze the antenna’s frequency response, while the finite difference time domain (FDTD) approach is used to analyze the antenna’s time-domain behavior. Overall, these methodologies give a thorough understanding of microstrip patch antenna performance and may be utilized to optimize their design. Furthermore, several patch antenna feeding methods, such as probe feed, microstrip line feeding, aperture coupling, proximity coupling, and CPW feed, are investigated. Attaching a microstrip line to the patch, which is subsequently linked to the RF source, is what microstrip line feeding entails. Aperture coupling entails making a hole in the ground plane that allows the RF source to feed the patch directly. Proximity coupling is accomplished by placing a probe near the patch, which creates an electromagnetic field on the patch. Patch antenna simulation software includes programmers such as HFSS, CST, and FEKO. These tools simulate the patch antenna’s performance, including its radiation pattern, gain, and input impedance. These simulations may be used to optimize the patch antenna design for specific applications. Moreover, recent antenna trends are presented in this article. [ABSTRACT FROM AUTHOR]

Integration of photovoltaic panels (PV) with electric vehicle (EV) charging stations could reduce the grid impact and carbon footprint from the extensive fast and ultra‐fast charging. This paper introduces a decoupled quad‐active‐bridge converter (QAB) with multi‐directional power flow capability, which can integrate PV, energy storage (ES), grid, and EV in a charging station and rule the power among them. As the number of ports increases in the multiple‐active‐bridge converter, the complexity of control increases exponentially because of power decoupling. For the QAB, by tuning one port in series with LC units, the decoupling is achieved between the other three ports, reducing the control difficulty significantly. Further, the resonance decoupling method is extended to the n‐port converter. For different power flows, the system automatically switches between different resonance modes to form higher‐efficiency power flow channels. Three operating modes with decoupled closed‐loop control methods have been constructed for the QAB to be suitable for future charging stations: (1) Charging mode: PV, ES, and grid coordinate with each other to provide incessant and stable charging for EV. (2) Electricity sales mode: Gird is supplied by PV, ES, and EV flexibly. (3) Under no load, PV power is stored locally. Experimental waveforms were presented by a 1‐kW prototype, verifying the effectiveness of power decoupling and the feasibility of the three operating modes. [ABSTRACT FROM AUTHOR]

High-Tc superconducting (HTS) receivers are promising candidates for terahertz (THz) communication applications due to their superior sensitivity and the cooling attainability with a miniature cryogenic system. Nevertheless, currently reported HTS mixers are mostly single-junction devices, and a more complicated architecture like the balanced configuration has not been investigated. This paper presents the design of a 600-GHz single-balanced HTS mixer, where detailed electromagnetic simulations are carried out to optimize the coupling efficiency and port isolation, as well as desired amplitude and phase relationship. To predict the noise and conversion performance, we present an innovative multiport network interleaving-based modeling method that enables powerful simulation verifications for single-balanced HTS Josephson mixers. Simulation results show that the presented device exhibits very good HTS mixer performance at the 600-GHz band, which validates the effectiveness of the design and the potential of the mixer for THz communication applications. [ABSTRACT FROM AUTHOR]

Abstract Multi‐terminal flexible DC power grid plays an important role in large‐scale new energy integration, which usually requires the installation of multi‐terminal DC circuit breaker (MTCB) at the intersection of multiple DC lines. At present, the research on multi‐terminal DC circuit breaker is mostly limited to theoretical simulation calculation, and there are few experimental studies and engineering applications. In this paper, a four‐terminal DC circuit breaker based on commutating path multiplexing is proposed, which combines with the compact natural commutation scheme of hybrid gap, greatly reducing the cost and volume of the circuit breaker. The commutation characteristics of the four‐terminal hybrid DC circuit breaker equivalent prototype at 10‐kV voltage level were tested. On this basis, the equivalent prototype of the circuit breaker test results shows that under 10‐kV voltage level, the four‐terminal circuit breaker topology can achieve breaking of 11 kA in 2.8 ms by the natural commutation method.

Abstract In this study, a direct synthesis approach is proposed to extract the coupling matrix of multi‐port filtering power divider (FPD) with arbitrary phase shift, power division as well as reference impedances, for the first time. This method provides an attractive technique to synthesise a multi‐functional device that combines the characteristics of bandpass filter, multi‐port power divider and ideal phase shifters as well as the impedance matching network, which can effectively diminish the overall size and improve the performance of the microwave front‐end network. A newly defined coupling matrix corresponding to arbitrary multi‐port topologies that introduces ideal phase shift by virtue of constant frequency‐independent reactance at the source and load is developed in FPD synthesis process. The coupling matrix is obtained directly by optimising the presented cost‐function in this paper, avoiding complex similar transformation process of coupling matrix. Finally, several numerical examples of multi‐port FPD with equal/unequal power division ratio, arbitrary phase shift and reference impedances are synthesised to well verify the proposed synthesis method, and a practical example is given to verify the validity of arbitrary phase shift and arbitrary reference impedance.

Multi‐terminal flexible DC power grid plays an important role in large‐scale new energy integration, which usually requires the installation of multi‐terminal DC circuit breaker (MTCB) at the intersection of multiple DC lines. At present, the research on multi‐terminal DC circuit breaker is mostly limited to theoretical simulation calculation, and there are few experimental studies and engineering applications. In this paper, a four‐terminal DC circuit breaker based on commutating path multiplexing is proposed, which combines with the compact natural commutation scheme of hybrid gap, greatly reducing the cost and volume of the circuit breaker. The commutation characteristics of the four‐terminal hybrid DC circuit breaker equivalent prototype at 10‐kV voltage level were tested. On this basis, the equivalent prototype of the circuit breaker test results shows that under 10‐kV voltage level, the four‐terminal circuit breaker topology can achieve breaking of 11 kA in 2.8 ms by the natural commutation method. [ABSTRACT FROM AUTHOR]

In this study, a direct synthesis approach is proposed to extract the coupling matrix of multi‐port filtering power divider (FPD) with arbitrary phase shift, power division as well as reference impedances, for the first time. This method provides an attractive technique to synthesise a multi‐functional device that combines the characteristics of bandpass filter, multi‐port power divider and ideal phase shifters as well as the impedance matching network, which can effectively diminish the overall size and improve the performance of the microwave front‐end network. A newly defined coupling matrix corresponding to arbitrary multi‐port topologies that introduces ideal phase shift by virtue of constant frequency‐independent reactance at the source and load is developed in FPD synthesis process. The coupling matrix is obtained directly by optimising the presented cost‐function in this paper, avoiding complex similar transformation process of coupling matrix. Finally, several numerical examples of multi‐port FPD with equal/unequal power division ratio, arbitrary phase shift and reference impedances are synthesised to well verify the proposed synthesis method, and a practical example is given to verify the validity of arbitrary phase shift and arbitrary reference impedance. [ABSTRACT FROM AUTHOR]

In this paper, a fuzzy-logic-based energy management system and a multi-port quasi-z-source converter that utilizes hybrid renewable energy sources are proposed. The system ensures that each energy source module can be used individually by employing fuzzy logic to define the power modes. This approach also helps to prevent switching losses resulting from the extra switching of the source modules. In addition, the proposed energy management does not have a mathematical model, so its applicability is simple, and it is suitable for different multiple-input topologies. The Mamdani fuzzy inference system can be designed to capture the nonlinear behavior of the system owing to linguistic rules. Moreover, the switching losses of the multiport modules were significantly reduced by adopting the quasi-z-source network to the end of the multiport converter. Furthermore, different errors, such as the root mean square error (RMSE), average squared error (ASE), average absolute error (AAE), average time-weighted absolute error (ATWAE), tracking error (TE), and unscaled mean bounded relative absolute error (UMBRAE), were applied to evaluate the fuzzy logic performance from different perspectives. The simulation results were obtained using MATLAB Simulink, and the experimental results were obtained by connecting the circuit to MATLAB Simulink using an Arduino Due. [ABSTRACT FROM AUTHOR]

Appropriate design of Multi-Port Converter (MPC) topology helps to overcome the difficulties of combining numerous renewable energy sources (RES). In this article, a comprehensive analysis of these MPCs in terms of their topologies, operating principles, various dependability, and overall efficacy is offered. There are two main types of MPCs which are non-isolated and isolated MPCs being coupled in parallel and series configurations to function as multi-input converters. These MPCs can flow the load power in one or both directions for the RES or BESS (battery energy storage system) applications. The non-isolated MPCs are most used in the latest years but they have some limitations such as small voltage gain, and failure in isolation. The isolated MPC is more effective than the non-isolated ones in terms of isolation between the input power stage and output but has some drawbacks such as the high cost, and large size of the high-frequency transformer (HFT). In this review paper, a high-efficiency voltage-regulator/battery energy storage system (VR-BESS) was presented as a multi-port DC-DC converter for the standalone PV (photovoltaic) array. This converter has fewer switches, is cheaper, and is more dependable than its counterparts. [ABSTRACT FROM AUTHOR]

Summary: This paper introduces the orthogonal rational approximation (ORA) algorithm for rational function approximation of transfer functions, based on data available from simulations or measurements. A rational function allows integration of such data in transient solvers for analysis of high‐frequency circuits. In rational function approximation, the unknown denominator polynomial of the model results in a nonlinear problem, which can be replaced with successive solutions of linearized problems following the Sanathanan–Koerner (SK) iteration. An orthogonal basis can be obtained based on Arnoldi resulting in a stabilized SK iteration. We present an extension of the stabilized SK, called ORA, which ensures real polynomial coefficients and stable poles for realizability of electrical networks. We also introduce an efficient implementation of ORA for multiport networks based on a block QR decomposition. [ABSTRACT FROM AUTHOR]

In determining a container loading plan on board, the goal is to find a container loading plan which considers the structural and operational boundary conditions. In the past, the container loading plan was made by the captain, but now the container terminal has an expert planner to determine the Master Bay Plan. The container loading plan is made in accordance with ship loading instructions with coordinators representing ship owners and cargo owners. The arrangement of containers to be loaded at certain ports into certain slots into the Bay Plan arrangement on the container ships will maximize capacity utilization and minimize operational costs. One important factor in achieving this goal is minimizing overloading -- a situation where the containers to be unloaded are blocked by containers destined for the next port. A container loading plan is difficult to make due to several factors: heterogeneity of packages in terms of size, weight, stack ability, position and orientation. The port transshipment pattern plays a unique place in a multiport network design. The transshipment port is the connecting port between the network route section and the feeder. Regular feeder lines connect the hub with several shallow feeder ports located in the same area as the hub port. The containers loaded on feeder vessels at one port are usually transported to more ports of destination. Feeder container route schedules -- including the date and time of arrival and departure -- must be notified in advance. [ABSTRACT FROM AUTHOR]

This article applies the generalized multimode S‐parameters to multiport antennas and radio frequency (RF) components for CAD applications. Consider the special case of impedance matching which could significantly simplify the multimode representation on port and remove the requirement on calculating port impedance. N single‐ended ports of a network are regarded as one generalized multimode port, supporting N orthonormal modes represented by N orthonormal basis vectors, respectively. By doing this, in antenna and RF component designs, one can only focus on specific modes interested, while ignore others. A multiport network's characteristics could be represented and understood in a much simpler manner because fewer but more intuitive physical quantities are considered. Therefore, this can significantly simplify the analysis, design, and optimization of multiport networks. For better illustration, several examples, including branch‐line coupler, mixed‐mode case, sequential rotation feeding antenna, and monopulse feed are analyzed and designed. Complicated analyses in network design using the single‐ended S‐parameters, including matching, amplitude and phase unbalance, could be converted into much simpler ones from the generalized multimode perspective. [ABSTRACT FROM AUTHOR]

The de‐embedding is a technique used in radio frequency and signal integrity measurements to extract the scattering (S)‐parameters of the device under test (DUT) from the measured data of a global assembly and based on known S‐parameters of the left and right test fixtures; thus, it removes the impact of the text fixtures used for the connection of the DUT to the instrumentation. Once the S‐parameters are measured, the de‐embedding is performed by a multistep approach involving the bidirectional transformation of the S‐parameters into the corresponding transfer scattering (T)‐parameters. The latter approach is well established for two‐ and four‐port networks and has been recently expanded to the multiport case. This work proposes an alternative analytical formulation to de‐embed a multiport device, knowing in advance only the S‐parameters of the global multiport assembly and those of the test fixtures. The proposed method does not involve the S‐to‐T conversion and it requires only the algebraic manipulation of the S‐parameter matrix elements; its practical implementation is very well fitted especially for multiport cases, and it is very fast in calculating the de‐embedded DUT S‐parameters for large port numbers. The results of the proposed formulation, applied to the case of a multipin high‐speed connector, are compared with those obtained by measurement and simulations. Their accuracy is shown and discussed to demonstrate the validity of the proposed approach. [ABSTRACT FROM AUTHOR]

This article presents a conformal antenna system for providing a dual-band high-gain communication link between an unmanned aerial vehicle (UAV) and a ground station where the two bands can be used independently for command-control and data link. A cylindrically conformal rectangular patch antenna operating in the higher order TM21 and TM03 modes is proposed, which produces high gain in both the frequency bands. This is possible by loading the cylindrical–rectangular patch antenna by a centrally located slot, which makes the radiation pattern of the TM21 mode broadside radiating and lowers the sidelobe level of the TM03 mode. Multiport network modeling (MNM) of the structure is done, which leads to the optimum design, and the effect of curvature on antenna performance is also studied. As the antenna has around 60° beamwidth in one of the planes for both the frequency bands, three such antennas are placed on one arm of a quadcopter UAV so that 180° coverage can be obtained by switching the antennas. The antenna system has a simulated gain of 7.94 and 10.21 dBi at 10.288 and 12.412 GHz, respectively. A single slot-loaded cylindrical–rectangular patch antenna is fabricated and the measured results are compared with those obtained by MNM and simulation. The antenna gives a gain of 7.46 and 9.83 dBi at the frequencies of 10.323 and 12.46 GHz, respectively. [ABSTRACT FROM AUTHOR]

• A concise and effective control scheme is proposed for the subgrids in the DC network to coordinate with the utility grid. • The proposed scheme adopts a unified control structure to ensure seamless mode transition. • The proposed scheme is decentralized and thereby reduces the dependency on communications. For complex networks with multiple subgrids formed by solid-state transformers, existing studies primarily focus on coordination within the networks in islanded mode, overlooking cooperation in grid-connected mode. To address this gap, this paper proposes a coordinated control scheme for the triple active bridge (TAB) converter in the grid-connected DC network. By establishing a droop relationship between the input power and the voltage difference, the TAB converter facilitates coordination between the utility grid and the DC network. The energy exchange with the utility grid is not only regulated by the TAB converter but also adjusted according to the utility grid state. So, the proposed scheme effectively facilitates coordination between the higher- and lower-level networks, strengthening system stability. Besides, the proposed scheme employs a unified control structure, which has power sharing and voltage regulation capabilities in grid-connected mode, as well as operating in islanded mode. This control structure enables the TAB converter to seamlessly transition across different operation modes, avoiding mode switching process and reducing the control complexity. Moreover, the proposed scheme is decentralized which negates the necessity for communication links, bolstering the system reliability. Lastly, the feasibility of the proposed scheme is analyzed in theory and validated by the hardware-in-loop tests. [ABSTRACT FROM AUTHOR]

In this paper, a series of compact power combiners are designed based on multimode transmission lines. Based on the multimode transmission lines, several multiport mode networks are constructed to achieve two-way, three-way, and four-way high-isolation power combinations. In detail, a four-port mode network based on a rectangular coaxial dual-mode transmission line and a five-port mode network based on a rectangular three-ridge three-mode transmission line are designed to achieve compact high-isolation two-way power combination. A six-port mode network based on a circular-coaxial three-mode transmission line is designed to achieve compact high-isolation three-way power combination. A nine-port mode network based on a four-ridge dual-coaxial six-mode transmission line is designed to achieve compact high-isolation four-way power combination. Based on a compact multimode transmission line, two-way, three-way, and four-way power combinations can be realized with single stages, high isolation, compact cross section sizes, low insertion loss, and high power capacity. The corresponding methods can be used to design several excellent power combiners. [ABSTRACT FROM AUTHOR]

• Analysis of traction power supply system is conducted considering cross-bonding cable. • Model simplification method based on multiport network hybrid parameters is designed. • The calculation difference of loss before and after consideration is more than 10 %. • Cross-bonding cables should be set near the position with large train power. The urban rail transit traction power supply system adopts DC power supply. The upstream and downstream rails are generally connected by cross-bonding cables at intervals, so as to decrease the rail equivalent resistance and reduce the rail potential and loss. The existing modelling methods for power flow calculation do not consider the influence of cross-bonding cables due to the complexity of modelling, which causes some deviations in the calculation results. Hence, a modelling method for power flow calculation of urban rail transit traction power supply system considering cross-bonding cables is proposed in this paper. Firstly, the influence of cross-bonding cables on power flow model is analyzed. Subsequently, a model simplification method based on multiport network hybrid parameters is designed. Finally, power flow calculations considering cross-bonding cables are carried out with a metro line. The calculation results show that the calculation difference of traction network loss before and after consideration is more than 10 %. Moreover, this paper analyzes the influence law of the setting of cross-bonding cables on the power flow state, and gives some suggestions on the setting in actual engineering application. [ABSTRACT FROM AUTHOR]

This article proposes and presents an innovative approach to realizing the concurrent dual-band transmission with only a single front-end and local oscillator at radio frequency (RF). Fundamentally, the proposed concurrent dual-band front-end is based on the conventional multiport interferometric architecture for single-band operation. Nevertheless, the conventional variable loads are replaced by diode networks with IF input signals to produce the RF signals at their designated center frequencies. Furthermore, due to the linear characteristics of a multiport network, the signals with different data contents will be mixed into both RF channels. To this end, an inverse matrix operation is applied to reversely convert the original data streams before the modulations of IF input signals. As a result, the two original data streams can be effectively modulated into specific RF channels (for transmission) with minimal interchannel interferences based on this configuration. In addition to the theoretical analyses, this innovative concurrent dual-band transmitting front-end has been investigated and verified with $M$ -quadrature amplitude modulation (QAM) signals in simulations and experiments. All outcomes demonstrate excellent performances in concurrent dual-band transmission with significant reductions in both size and biasing power. [ABSTRACT FROM AUTHOR]

A novel leaky-wave antenna (LWA) array capable of bilateral beamforming is investigated for applications in indoor and short-distance mobile communications. The antenna array is designed on a double-layer substrate-integrated waveguide (SIW) with a multiport feeding network. The upper layer is a four-port SIW with a tapered open stopband suppression structure and two tapered radiating slot arrays. By adjusting the periods and widths of slots, the two slot arrays radiate in different directions, and their radiation fields satisfy the cosecant-squared distribution. The lower layer is a single-port SIW power divider with an allocation ratio of 1:5 using a Z-shaped junction. There are transitions at both ends of the lower SIW for coupling energy up into the radiation layer. When feeding the upper layer from its two input ports individually, two dual broad beams with beam directions of ±25° and ±45° can be generated, thus achieving amplitude-shaped dual-beam switching for smart beam switching antenna systems applied in short-distance mobile communication. When feeding the whole double-layer array through the input port of the power divider, the above two dual beams will be superposed together and form a cosecant-squared radiation pattern, which is suitable for uniform radio wave coverage along with straight areas. The proposed array was fabricated and measured to validate its performance, and the results showed the efficiency of the design. [ABSTRACT FROM AUTHOR]

An annular patch antenna operating in both TM04 and TM05 modes and conformed to a conical surface is proposed for airborne applications. Dual‐slot loading is done to obtain a high gain linearly polarized broadside radiation pattern in both the modes of operation by introduction of additional equivalent magnetic currents. Cavity model analysis of a conical annular patch antenna is carried out and is further extended to obtain the multiport network modeling (MNM) of the dual‐slot loaded conical annular patch antenna. Additional control over directivity and side lobe level can be achieved by variation in ratio of slot lengths. The effect of curvature on the antenna performance is studied using MNM. The antenna produces a gain of 9.26 and 8.83 dBi in X‐band frequencies of 9.838 and 10.323 GHz respectively. [ABSTRACT FROM AUTHOR]

This article presents a new compact multiplexer structure and its design approach, based on a novel resonant manifold. Different from typical transmission-line-based manifold multiplexers, the proposed manifold junction is formed of coupled resonators, so that the manifold also contributes to the filtering poles and selectivity in the passbands. The all-resonator configuration achieves a more compact footprint than the conventional manifold. This multiport filtering network can be represented by a single coupling matrix which can be obtained by using a robust optimization-based method. Tailored channel frequency allocation schemes are presented for the proposed multiplexers with a different number of channels. To validate the proposed concept, a triplexer and a five-channel multiplexer, both at X-band, are designed and tested using rectangular waveguide technology. Good agreements have been achieved between the measurement and simulations. Comparisons have been made with conventional multiplexers. [ABSTRACT FROM AUTHOR]

Microwave imaging based on the inverse scattering problem has attracted many interests in microwave community. To obtain a satisfactory imaging quality, in most cases, a scattering-free environment is desired. In this work, to provide such an environment, we experimentally demonstrate a compact microwave imager integrated with a board-integrated, multiport vector network analyzer and a miniaturized, cylindrical anechoic chamber dedicatedly designed for inverse scattering-based microwave imaging. Based on the principle of electrically induced transparency and the effective medium equivalence, an inhomogeneous, ultrathin, dual-angle absorbing surface was designed, simulated, and implemented, to simultaneously absorb incident and scattered fields. Experimental imaging verified its effectiveness. The proposed imager would help the promotion of practical imaging, showing the potential in on-side imaging. [ABSTRACT FROM AUTHOR]

This article presents an electromagnetic compatibility (EMC) aware motor design method based on the prediction of the impedances of a stator winding structure. The stator structure is divided into several two-dimensional parts, and their network parameters are extracted by electromagnetic (EM) simulations. Through conversion and synthesis of the multiport network parameters, the input impedance can be found for the full-winding structure. The calculated input impedance approximately follows the measured impedance of tested induction motors. The impedance calculation method has been realized in a parametric analysis platform to enable the EMC-aware design of induction motors. By using the platform, the variations of the input impedances by different design parameters can be analyzed along with consideration of loss and torque ripple. To verify the proposed method, prototype motors were assembled and the common-mode (CM) currents were measured under driving operation. The results show that the CM current can be reduced up to 10 dB in the frequency range of interest when the number of parallel circuit is reduced, as estimated from the calculated input impedances. [ABSTRACT FROM AUTHOR]

The paper presents a method of optimizing frequency characteristics of filter banks in terms of their implementation in digital CMOS technologies in nanoscale. Usability of such filters is demonstrated by frequency-interleaved (FI) analog-to-digital converters (ADC). An analysis filter present in these converters was designed in switched-current technique. However, due to huge technological pitch of standard digital CMOS process in nanoscale, its characteristics substantially deviate from the required ones. NANO-studio environment presented in the paper allows adjustment, with transistor channel sizes as optimization parameters. The same environment is used at designing a digital synthesis filter, whereas optimization parameters are input and output conductances, gyration transconductances and capacitances of a prototype circuit. Transition between analog s and digital z domains is done by means of bilinear transformation. Assuming a lossless gyrator-capacitor (gC) multiport network as a prototype circuit, both for analysis and synthesis filter banks in FI ADC, is an implementation of the strategy to design filters with low sensitivity to parameter changes. An additional advantage is designing the synthesis filter as stable infinite impulse response (IIR) instead of commonly used finite impulse response (FIR) filters. It provides several dozen-fold saving in the number of applied multipliers.. The analysis and synthesis filters in FI ADC are implemented as filter pairs. An additional example of three-filter bank demonstrates versatility of NANO-studio software. [ABSTRACT FROM AUTHOR]

A novel approach to de‐embed the frequency response of filters connected to a 2‐channel multiplexer without the need for unplugging is proposed. The technique to manifold coupled multiplexers with arbitrary number of filters is also theoretically generalised. In multiplexer tuning, there are practically important circumstances in which it is advantageous to de‐embed the frequency response of filters in multiplexers without detaching them. The authors show that using a novel technique and reasonable approximations, all filters of a multiplexer can be modelled by simple microwave networks, and then, the equivalent rational function of the channel filters can be estimated appropriately by the rational H2 approximation; extraction of this model facilitates tuning of the filters using the coupling matrix method. The impact of mechanical tolerances on the accuracy of the proposed technique is also studied. Next, this method is examined on a 2‐channel multiplexer and its application in de‐embedding and tuning of its connected filters is verified. Provided that the mechanical tolerances of the structure are sufficiently small, this technique is a powerful engineering solution towards tuning of manifold‐coupled multiplexers. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to passivity enforcement of multiport frequency-dependent rational models. The strategy employs graph theory, and convex optimization to extend the positive-definite matrix completion problem to passive system completions. The main distinguishing feature of the proposed technique relative to those in the literature is that passivity compensations are only applied to those parameters contributing to passivity violations, in a completion manner. Numerical experiments using actual transformer data reveals that the proposed method results in models with increased accuracy. [ABSTRACT FROM AUTHOR]

This work describes a generalized multitone multiharmonic scattering parameters ($\mathbf {M^{2}S}$ -parameters) measurement approach suitable for multiport nonlinear network characterization in the wave-variable domain. Based on the incommensurate (or offset) frequency concept, the $\mathbf {M^{2}S}$ -parameters are directly measurable quantities independent of the incident wave phases and display a mild nonlinear dependence on the incident wave amplitudes. They feature a well-defined relationship with the frequency-domain nonlinear transfer functions derived from the Volterra theory, representing a generalization to the multiinput multiharmonic case of the widely used single-input single-frequency describing function approach. The proposed framework allows to capture the nonlinear steady-state behavior from a reduced set of measurements and can be effectively exploited for performance prediction in application-like scenarios. The approach is here applied to RF transistor and power amplifier load-pull measurements, as well as to the case of broadband modulation, showing that the performance assessment of the device can be obtained in a straightforward way from the $\mathbf {M^{2}S}$ -parameters description. [ABSTRACT FROM AUTHOR]

Multiple expansion points are introduced to the multiport Cauer ladder network method to realize an efficient model order reduction of an eddy-current field. The proposed method can set multiple target frequencies to cover a wide frequency range with a small number of multiport electric network elements. A time-dependent response to pulsewidth-modulation (PWM) excitation is accurately reconstructed by setting the target frequencies at both fundamental and carrier frequencies. [ABSTRACT FROM AUTHOR]

A slot loaded annular sector microstrip antenna having a pentaband operation is presented. The antenna has six resonant frequencies and the fourth band occurs between the fourth and fifth resonance. The radiation pattern is linearly polarized at all the frequencies. The radiation is broadside directed at the first three bands, tilted at the fourth and split at the fifth band. The resonant frequencies are located at 3.543 (Sub-6 GHz 5G band), 5.118 (ISM 5.2 GHz), 5.625 (WiMAX 5.8 GHz), 8.463, 9.534 and 11.25 GHz. Analysis of the structure is done using Multiport Network Modeling which fairly accurately predicts the resonant frequencies of the structure. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to correctly define the hybrid equivalent circuits. These circuits allow the separation of the linear portions of electronic circuits from the nonlinear ones and in this way the polarization process of electronic devices becomes much more efficient. When linear and/or nonlinear analyzed circuits have a small number of nonlinear circuit elements, their analysis, synthesis, and simulation are performed more efficiently if the nonlinear part of circuit is separated from the linear one. A new modeling technique, called H ~ modeling, is introduced for multi-port networks. It is shown that H ~ models are more dynamic compared to equivalent Thevenin or Norton circuits and have the ability to describe port behavior more accurately. A special type of model H ~ is also introduced, called model H ~ nullified, or simply model H ~ and many properties of H modeling are investigated, including circuit energy management. It is shown that the H models are not limited to single-port networks, but also cover multiport. A major property of H modeling is the local polarization of transistors. It separates the nonlinear components from the linear portion of circuit for faster and more efficient polarization of circuit. Here a designer can take advantage of H-modeling and bias individual transistors (or in combinations) with no need to perform the normal circuit biasing. The proposed strategy separates linear and nonlinear portions of an analog circuit and takes more control of nonlinear portions. This separation of portions (components) of circuit is achieved by introducing a new port model that cancels the ports of nonlinear devices. In turn, this leads to a new technique for polarizing nonlinear components. This separation of portions (components) within the circuit is accomplished by introducing a new port modeling that nullifies the ports of nonlinear devices. [ABSTRACT FROM AUTHOR]

The dispersion characteristics of a glide-symmetric holey periodic surface are investigated, with special emphasis on a detailed study of its stopbands. The unit cell is modeled as a multiport network associated with multiple modes at each of the lattice boundaries. Enforcing the periodic conditions, the real and imaginary parts of the wavenumbers of the Floquet modes are calculated through an eigenproblem posed in terms of the generalized multimodal transfer matrix, which is computed from the scattering parameters obtained with a full-wave simulator. This procedure allows us to take into account the higher order modal couplings between adjacent unit cells that are crucial for accurate dispersion analysis. The resulting simulation-assisted approach provides both a convenient computational tool and a very fruitful physical insight that reveals the existence of complex modes, the convergence of opposite-parity modes, and the anisotropy in both passband and stopband. This approach enables a precise calculation of the attenuation constant, which is not possible with conventional techniques as the eigenmode solvers of commercial software. Based on this approach, an extensive parametric study is carried out, rigorously establishing a set of critical criteria for the use of such a periodic surface as an electromagnetic bandgap structure in gap waveguide technology. Moreover, the analysis of the directional properties of the structure is applied to further suppress the leakage. [ABSTRACT FROM AUTHOR]

Summary: Selecting the quantum signals with respect to features like direction of propagation or impinging energy makes a ubiquitous operation that is employed in a variety of quantum engineering applications. The conditions for optimally selective angular and energy filtering via homogeneous planar inclusions are determined and the derived designs exhibit substantial robustness with respect to fabrication defects. The reported findings may open new uncharted directions towards the efficient design of integrated devices exploiting quantum filtering from sharp sensors and tuners to multiport networks and quantum circuits. [ABSTRACT FROM AUTHOR]

This paper presents a seven-port modulator capable of switching the polarization state of the transmitting signal. Similar to the six-port modulator, the proposed device modulates the carrier signal through the reflection coefficients generated by four variable loads. The additional seventh port allows feeding two antennas or a dual-port antenna. The loads control both the complex envelope and the polarization of the transmitted carrier signal. The mathematical model of the device, developed in this paper, is applied to analyze its performance and different modes of operation. For validation, a prototype is manufactured for a center frequency of 1575.42 MHz. It is used to generate M-quadratic-amplitude modulation at different polarizations. The signals recorded at the output of the prototype show good agreement with the values predicted by the model. [ABSTRACT FROM AUTHOR]

This paper presents for the first time a theoretical proof that at certain frequencies it may be impossible to match a nonuniform multiconductor transmission line by terminating it with a multiport load network of only passive partial admittances. The analytical proof is based on a detailed modal analysis of the chain connection of two unequal uniform lossless line sections, each one made of two parallel wires above ground. We show that, when the propagation modes of the resulting nonuniform MTL are about to resonate, the matching load network of partial admittances will require the presence of one negative resistor. [ABSTRACT FROM AUTHOR]

Highlights • A method for determining the paths for a port to upgrade its industry was provided. • A method for determining the optimal scale of a port cluster was proposed. • A multiperiod investment and withdrawal scheme to integrate the ports was designed. Abstract Port integration in a region with multiport gateways (R-MPG) is studied in the case when port supply surpasses shipping demand. First, the feasible paths for ports with overcapacity to transform and upgrade their industry are analyzed. Second, a method for determining the optimal scale of port clusters is put forth based on a continuous approximation approach. Then, a multi-period integration decision model and port integration method is proposed. Finally, two typical R-MPGs in China are used for empirical studies. [ABSTRACT FROM AUTHOR]

Most techniques for power system analysis model the grid by exact electrical circuits. For instance, in power flow study, state estimation, and voltage stability assessment, the use of admittance parameters (i.e., the nodal admittance matrix) and hybrid parameters is common. Moreover, network reduction techniques (e.g., Kron reduction) are often applied to decrease the size of large grid models (i.e., with hundreds or thousands of state variables), thereby alleviating the computational burden. However, researchers normally disregard the fact that the applicability of these methods is not generally guaranteed. In reality, the nodal admittance must satisfy certain properties in order for hybrid parameters to exist and Kron reduction to be feasible. Recently, this problem was solved for particular cases of monophase and balanced triphase grids. This paper investigates the general case of unbalanced polyphase grids. First, conditions determining the rank of the so-called compound nodal admittance matrix and its diagonal subblocks are deduced from the characteristics of the electrical components and the network graph. Second, the implications of these findings concerning the feasibility of Kron reduction and the existence of hybrid parameters are discussed. In this regard, this paper provides a rigorous theoretical foundation for various applications in power system analysis. [ABSTRACT FROM AUTHOR]

A multichip multiport communication network technology is proposed based on a network of dielectric waveguides. For optimum performance and best versatility, a combination of high-permittivity dielectric slab waveguide and low-permittivity flexible dielectric rod waveguide is proposed. Additional building blocks are a dielectric waveguide Y junction and transitions between waveguide types as well as between chip and waveguide. The resulting multichip multicast multiport interconnect network features low overall transmission loss and small chip-area consumption for the chip-to-waveguide transitions. Measurement results for all components are presented for frequency bands around 60 GHz and around 100 GHz. The insertion loss of the transition from on-chip microstrip line to dielectric slab waveguide, extracted from end-to-end measurements, is 3.3 dB around 60 GHz and 2.2 dB around 100 GHz. Experimental four-terminal networks, each comprising four chip-to-waveguide transitions and two dielectric waveguide Y junctions, show measured end-to-end insertion loss (including pass through two Y junctions and two chip-to-waveguide transitions) of 21 dB (around 60 GHz, covering 26-mm distance) and of 17 dB (around 100 GHz, covering 20-mm distance), respectively. These values outperform wireless interconnects by far and emphasize the performance and versatility of the proposed approach for chip-to-chip multicast multiport interconnects. [ABSTRACT FROM AUTHOR]

This paper presents a fusion design approach of multiport (1-to- $N$) in-phase/antiphase power dividing network with a bandpass response, which can be applied in constructing either the balanced or single-ended filtering power divider. The relationships of external $Q$ -factors ($Q_{e}\text{s}$) between the in-phase/antiphase ports are constructed, and it is found that their $Q_{e}$ ratio is determined by power allocation regardless of the phase difference. Meanwhile, the two functions of power allocation and bandpass response can be designed independently. Based on the theoretical analysis, two kinds of filtering power dividers using the dielectric resonator (DR) are proposed. One is balanced and the other is single ended. Both of them can be easily built by properly adding feeding probes for the DR without increasing the circuit size, while the phase difference between the ports can be adjusted to be either in-phase or antiphase by altering the direction of the feeding probes. To verify the proposed design concept, the filtering power dividers mentioned earlier are simulated. Some of them are implemented and measured, and their measured results match well with the simulated data, showing good performance, such as low loss and good selectivity. [ABSTRACT FROM AUTHOR]

This study proposes a new adaptive and centralised under-voltage load shedding (UVLS) to prevent short-term voltage instability; it then examines the challenges related to the centralised UVLS. The proposed method uses a local measurement to estimate the amount of load shedding. It decreases the amount of load shedding by selecting the proper location of UVLS and shedding more powers within seconds after activating UVLS. Dynamic simulations are performed on the IEEE 118-bus test system, New England test system, and on Isfahan regional power grid (IRPG) as the case studies. Simulation results, when compared with the conventional multi-port network model and sensitivity-based methods, provide a considerable reduction in the active power shedding in addition to the number of the load shedding steps. Moreover, it indicates that the measurement bias errors have a considerable effect on UVLS. Finally, a method is introduced to overcome the effect of measurement errors. [ABSTRACT FROM AUTHOR]

Distinct from the conventional machines with only one electrical and one mechanical port, electrical machines featuring multiple electrical/mechanical ports (the so-called multiport electrical machines) provide a compact, flexible, and highly efficient manner to convert and/or transfer energies among different ports. This paper attempts to make a comprehensive overview of the existing multiport topologies, from fundamental characteristics to advanced modeling, analysis, and control, with particular emphasis on the extensively investigated brushless doubly fed machines for highly reliable wind turbines and power split devices for hybrid electric vehicles. A qualitative review approach is mainly adopted, but strong efforts are also made to quantitatively highlight the electromagnetic and control performance. Research challenges are identified, and future trends are discussed. [ABSTRACT FROM PUBLISHER]

In regional and local 3-kV dc railway lines, energy storage systems (ESS) along the catenary can manage energy coming from electrical braking; in the actual low-carbon economy scenario, besides environmental considerations, better energy utilization goes to a general rationalization of the existing and future electrical substations. Modular multiport converters based on power electronic transformers and ESS can be used for this purpose. This work analyzes as case study a regional 3-kV dc line, obtaining by simulations and GPS measurements the train current and the pantograph voltage profile on the catenary. Energy savings are calculated placing ESS and multiport converters inside existing substations. [ABSTRACT FROM PUBLISHER]

Design, fabrication and characterization of a novel RF switch is proposed in this paper. The multiport RF MEMS switch provides a single input multiple output novel topology suitable for satellite payload applications. A single ETA is used to switch the device from one mode to another. When a voltage difference is applied across the electrode pads of ETA, and depending on the configuration, the actuator actuates forward or backward in plane producing either a quad or dual output respectively. The reflection loss and insertion loss are improved effectively. Measurement results show that in `dual mode’ position, the input reflection coefficient (S11) is less than − 50 dB with the forward transmission coefficient (S21) better than − 2 dB at 0-15 GHz. At ‘quad mode’, position, the input reflection coefficient (S11) is less than − 55 dB with the forward transmission coefficient (S21) better than − 4 dB at 0-15 GHz. The larger than 50 dB over 0-15 GHz isolation realized in both modes of operation ensures dual and quad mode outputs without information loss. The actuation voltage is reduced to 4.5 V. The measured power handling capability can reach up to 35 dBm while the power consumption of the switch is 50 mW. This compact RF MEMS capacitive switch possesses excellent performances in terms of low insertion loss, high isolation, low power and high power handling capability. [ABSTRACT FROM AUTHOR]