bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal placement of static compensators for multi‐objective voltage stability enhancement of power systems
Authors: Xu Yan , Dong Zhao Yang , Xiao Chixin , Zhang Rui , Wong Kit Po
Published: August 2015

Static compensators (STATCOMs) are able to provide rapid and dynamic reactive power support within a power system for voltage stability enhancement. While most of previous research focuses on only an either static or dynamic (short‐term) voltage stability criterion, this study proposes a multi‐objective programming (MOP) model to simultaneously minimise (i) investment cost, (ii) unacceptable transient voltage performance, and (iii) proximity to steady‐state voltage collapse. The model aims to find Pareto optimal solutions for flexible and multi‐objective decision‐making. To account for multiple contingencies and their probabilities, corresponding risk‐based metrics are proposed based on respective voltage stability measures. Given the two different voltage stability criteria, a strategy based on Pareto frontier is designed to identify critical contingencies and candidate buses for STATCOM connection. Finally, to solve the MOP model, an improved decomposition‐based multi‐objective evolutionary algorithm is developed. The proposed model and algorithm are demonstrated on the New England 39‐bus test system, and compared with state‐of‐the‐art solution algorithms.
Optimal scheduling of virtual power plant with battery degradation cost
Authors: Zhou Bin , Liu Xi , Cao Yijia , Li Canbing , Chung Chi Yung , Chan Ka Wing
Published: August 2015

This study proposes a novel optimal generation scheduling model for virtual power plant (VPP) considering the degradation cost of energy storage system (ESS). The VPP is generally formed by a mix of distributed energy resources, and the ESS is an important installation for flexible VPP dispatch due to its controllable and schedulable behaviours. For the operations of battery storage systems, the ambient temperature and depth of discharge have significant impacts on the wear and tear of the ESS as well as battery degradation cost. Furthermore, the battery degradation cost is modelled and approximated by a piecewise linear function, and then incorporated into the proposed optimal VPP scheduling model. Consequently, the optimal VPP scheduling problem is formulated as a two‐stage stochastic mixed‐integer linear programming in order to maximise the expected profits of the VPP. The proposed model has been successfully implemented and tested through a representative case study, and the influence of battery degradation cost on optimal VPP scheduling has also been thoroughly analysed and demonstrated.
Reliability benefit of energy storage in wind integrated power system operation
Authors: Thapa Suman , Karki Rajesh
Published: August 2015

Variability of wind power is one of the main concerns of power system operation with significant wind power. Energy storage can be employed in conjunction with wind power to reduce the uncertainty associated with wind power. This study assumes the storage facility being operated by the wind farm operator for the explicit purpose of minimising the risk of wind power commitment. A time‐dependent wind power model is developed in conjunction with the energy storage model for short operating lead times that are conditional on the initial wind and storage conditions. This study presents a probabilistic method to assess the reliability contribution of energy storage using two probabilistic indices: the wind power commitment risk and the unit commitment risk.
Analysis of unbalanced distribution lines with mutual coupling across different voltage levels and the corresponding impact on network voltage
Authors: Yan Ruifeng , Saha Tapan Kumar
Published: August 2015

In many countries, it is common for medium voltage (MV) and low voltage (LV) to share the same pole and power line corridor, and this has been a general practice for decades. The MV line and the LV line separation distance may be short under some situations; therefore the mutual coupling may become substantial, which can have a significant impact on network voltages. In the literature, such coupling effect is generally ignored, and there is a lack of a detailed model of the coupled MV and LV lines for incorporation into load flow programs. This study develops a model for unbalanced distribution lines considering the mutual coupling between different voltage levels. Then the established model is utilised in a current injection load flow program to analyse the MV/LV coupling impacts on distribution system voltage.
Control scheme of the de‐icing method by the transferred current of bundled conductors and its key parameters
Authors: Jiang Xingliang , Wang Yaoxuan , Shu Lichun , Zhang Zhijin , Hu Qin , Wang Quanlin
Published: August 2015

Transferring the current of bundled sub‐conductors through smart switching modules is a promising de‐icing method. This study explores the application of line impedance modulation to line de‐icing. The control requirements of the de‐icing method by transferred current are illustrated according to the characteristics of the method, and two key parameters, namely, critical ice‐melting current and ice‐melting time, are introduced. The analytical expression for the critical ice‐melting current is deduced theoretically. On this basis, the effect of icing shape on the critical ice‐melting current is analysed and discussed, along with the calculation of the critical ice‐melting current when icing on the windward surface of conductor. A simplified method for calculating ice‐melting time is presented on the basis of the heat balance equation during the ice‐melting process. With the control requirements of this method as a framework, the calculation and selection of the grouping mode and current duration for the sub‐conductors are discussed, and the control scheme of the de‐icing method by transferred current is established. The control scheme is preliminarily validated by laboratory investigations conducted in an artificial climate chamber. The results can serve as a reference for obtaining the ice‐melting scheme when de‐icing via the transferred current of bundled conductors.
Binary fish swarm algorithm for profit‐based unit commitment problem in competitive electricity market with ramp rate constraints
Authors: Singhal Prateek Kumar , Naresh Ram , Sharma Veena
Published: August 2015

This study presents a new approach based on a binary fish swarm algorithm (BFSA) and dynamic economic dispatch (DED) method for generation companies (GENCOs) profit (PF)‐based unit commitment (PBUC) problem considering power and reserve generations simultaneously in a day‐ahead competitive electricity markets. BFSA is used to decide the units on/off status, whereas the optimum dispatch solution is determined using DED method with modified unit generation limits because of ramp rate constraints over the complete scheduled time horizon. To avoid the search to get trapped at a local optimal solution, swap move‐based local search and cyclic re‐initialisation operators are embedded in BFSA. Moreover, two strategies for selling power and reserve are considered in problem formulation and implementation phase. Its effectiveness is validated on 10 and 100 thermal units in a day‐ahead electricity market in terms of GENCOs PF and computation time. The results obtained for PBUC problem with BFSA method have been compared with those obtained with priority list, dynamic programming, Lagrange relaxation, genetic algorithm and binary artificial bee colony algorithm, and BFSA has been found effective to achieve quality solutions in reasonable computation time.
Advanced application of transient stability constrained‐optimal power flow to a transmission system including an HVDC‐LCC link
Authors: Calle Ignacio A. , Ledesma Pablo , Castronuovo Edgardo D.
Published: August 2015

In this study, a transient stability constrained‐optimal power flow (TSC‐OPF) model is proposed and applied to a real case in the currently interconnected Balearic Islands‐Iberian Peninsula system. The TSC‐OPF retains the dynamics of all generators in the islands with fourth degree transient synchronous generator models and includes a representation of a high‐voltage direct current (HVDC) link on the inverter side. The proposed large‐scale non‐linear optimisation problem, programmed in GAMS and solved using the CONOPT tool, is used to assess the economic impact of the HVDC on the Balearic Islands generation cost under different circumstances, using TSC‐OPF and traditional OPF on the dispatch. Different recovery patterns of the HVDC link after a severe fault in the transmission grid are evaluated from the viewpoint of the cost and stability of power generation.
Analytical approximate calculation of losses for modular multilevel converters
Authors: Wang Haitian , Tang Guangfu , He Zhiyuan , Cao Junzheng , Zhang Xiaoping
Published: August 2015

The voltages of the upper and lower arms per phase unit in a modular multilevel converter (MMC) are analysed. In addition, the enabled probabilities of each submodule (SM) in the upper and lower arms are proposed on the basis of the relationship between the arm voltage and the number of enabled SMs. Analytical models of the currents in the switches can be obtained from the current path and sign. Then, the average or root mean square (RMS) current can be obtained from the corresponding model. Therefore, the conduction and essential switching losses can be expressed by analytical formulas. In the inverter and rectifier modes, the two losses of the corresponding upper and lower switches of the SM are compared, and the sums of the two losses of the upper and lower switches are compared with the analytical method. Simulation studies are performed on a 1000 MW 320 kV MMC‐high‐voltage direct current system under typical operating conditions. The magnitudes of the compared losses are validated by the simulation results. Both the relative errors of the total conduction and essential switching losses are within ±2.5 and ±7%, respectively, and the comparison results demonstrate the effectiveness of the analytical method.
Excitation control of a synchronous generator using a novel fractional‐order controller
Authors: Asadollahi Mostafa , Rikhtegar ghiasi Amir , Dehghani Hassan
Published: August 2015

Fractional calculus (FC) is widely used in a variety of fields, such as science and engineering. FC is recognised for its ability to produce a superior modelling and control in dynamical systems. Fractional controllers are known to be more efficient. In this paper, fractional‐order control systems are studied with regard to control input energy efficiency, which is a noteworthy issue in designing control systems. In this study, improved tilt‐integral–derivative (I‐TID) is proposed. To validate the proposed controller, its results were compared with that of proportional–integral (PI) controller, fractional PI (F‐PI) controller, and conventional tilt‐integral–derivative (TID) controller. A genetic algorithm was used to tune the parameters of the aforementioned controllers. Simulation results revealed that the proposed controller is not only energy efficient, but also fast. The results also indicated that the performance of I‐TID is much better than PI, F‐PI, and conventional TID.
Improving method of robust transmission network expansion planning considering intermittent renewable energy generation and loads
Authors: Chatthaworn Rongrit , Chaitusaney Surachai
Published: August 2015

This study presents a novel method for robust transmission network expansion planning (RTNEP) considering intermittent renewable energy generation and loads. The investment cost of transmission line and operating cost are considered as the objective function of the planning. This study proposes to select the suitable scenarios to make the robust expansion plan for all possible scenarios based on intermittent renewable energy generation and loads data in a year. Meta‐heuristic algorithm called adaptive tabu search (ATS) is employed in the proposed RTNEP. ATS iterates between the main problem, which minimises the investment cost and operation cost and the subproblem, which minimises the total power generation of conventional generators and curtailments of renewable energy generation and loads. This study uses AC load flow based on Newton–Raphson method and non‐linear programming (NLP) based on interior point method for solving the main problem and the subproblem, respectively. IEEE Reliability Test System 79 (RTS 79) is used for testing the proposed method. The results show that the proposed expansion plan is more robust than the solutions from other research works.
Performance analysis of a new fast negative sequence power injection oriented islanding detection technique for photovoltaic photovoltaic based voltage source converter based micro grid operation
Authors: Dhar Snehamoy , Dash Pradipta Kishore
Published: August 2015

This study presents a new study on islanding detection method for photovoltaic (PV) based voltage source converter (VSC) system incorporated with multiple distributed energy resources‐based microgrid. The VSC system is basically controlled by positive sequence power–voltage loop, where dc‐link capacitor voltage and point of common coupling power components are measured parameters. During grid disconnection an islanding detection loop is further implemented with existing control, based on negative sequence active and reactive powers of coupling bus. The threshold for the feedback sequence voltage is determined to maintain a negligible non‐detection zone and to avoid false detection during other power quality issues. A binary tree classifier is adopted for threshold filter design to perturb disturbance parameters only during islanding events. Worst‐case scenario is considered by implementing a PV‐based VSC system from IEEE UL 1741 standard. The performance of the proposed islanding detection technique is investigated in MATLAB/ Simulink environment. The efficient detection of islanding with a fast run on time is ensured by the result analysis, where no significant effect in power quality during normal operating condition has been maintained.
Optimisation model for power system restoration with support from electric vehicles employing battery swapping
Authors: Sun Lei , Wang Xiaolei , Liu Weijia , Lin Zhenzhi , Wen Fushuan , Ang Swee Peng , Salam Md. Abdus
Published: August 2015

The energy stored in the batteries of electric vehicles (EVs) could be employed for starting generators when a blackout or a local outage occurs. Considering the feature of the battery swapping mode, an available capacity model of the batteries in a centralised charging station is first developed. Then, the authors analyse the start‐up characteristics of a generator powered by batteries and propose a bi‐level optimisation‐based network reconfiguration model to determine the restoration paths with an objective of maximising the overall generation capability. In the upper‐level optimisation model, the generator start‐up sequence is optimised, whereas the restoration paths are optimised in the lower‐level one. Moreover, they consider the uncertainties associated with the available capacity of the batteries. The bi‐level optimisation model for the network reconfiguration is developed in the chance‐constrained programming framework and solved by the well‐established particle swarm optimisation algorithm. Finally, case studies are employed to demonstrate the effectiveness of the presented model. Simulation results show that a centralised EV charging station could act as a power source to effectively restore a power system without black‐start (BS) generators or with insufficient cranking power from BS generators, and the presented model could be used to guide actual system restorations.
Look‐ahead distribution power restoration analysis based on integrated operation of distribution automation and advanced metring infrastructure systems
Authors: Balakrishna Pamulaparthy , Rajagopal Kommu , Swarup K.S.
Published: August 2015

Power restoration schemes incorporated into Distribution Automation (DA) system helps in quickly restoring the power during emergency situations like faults. Due to the numerous advancements made in the distribution system operation in recent times, power restoration analysis needs to be done in a look‐ahead manner based on system wide operational & monitored data apart from just fault data processing during the outages. With the evolution of Advanced Metering Infrastructure (AMI) during recent times, it is now possible to design the look‐ahead restoration schemes by integrating the operation of DA with AMI system using internet protocol based communications, preferably. In this paper, we propose a novel method for power restoration analysis which execute all pre‐defined restoration schemes in a look‐ahead manner by representing distribution system as a weighted graph and computing graph weights based on representation of DA & AMI system's current operational/measured/constraint data from each distribution load segment. Computed graph weights are converted to restoration indices with associated ranking based mechanism to indicate criticality & considerations for each power restoration scheme in case of fault occurrence in real‐time. A case study on the standard RBTS test system has been demonstrated for the proposed method.
Calculation of effective parameters of high permittivity integrated artificial dielectrics
Authors: Barzegar‐Parizi Saeedeh , Rejaei Behzad
Published: August 2015

An analysis is presented of the effective electromagnetic parameters of high‐permittivity, anisotropic artificial dielectrics which are built by stacking arrays of metallic elements and conventional dielectric films, with adjacent arrays shifted with respect to each other. The effective parameters of the artificial dielectric are extracted from the scattering coefficients of plane electromagnetic waves which are normally or obliquely incident on a slab of the artificial material with finite thickness. These coefficients are derived from the generalised scattering matrix of a single layer of metallic elements which is computed using the integral equation technique. Both two‐dimensional and three‐dimensional configurations are considered. Calculations demonstrate the feasibility of artificial dielectric films with extremely high values of effective relative permittivity (several thousands) in the plane of the film at millimetre‐wave (mm‐wave) frequencies. These artificial dielectrics have a high potential for application in microwave and mm‐wave integrated circuits because of their high‐permittivity and planar layout. As a potential application, the authors propose an artificial dielectric waveguide integrated on a silicon substrate.
Lens‐coupled folded‐dipole antennas for terahertz detection and imaging
Authors: Rahman Syed M. , Jiang Zhenguo , Xing Huili (Grace) , Fay Patrick , Liu Lei
Published: August 2015

The authors report the design, simulation and characterisation of lens‐coupled folded‐dipole antennas (LC‐FDAs) for terahertz (THz) detection and focal‐plane imaging arrays. LC‐FDAs operating at 200 GHz have been designed on semi‐insulating silicon wafers with a resistivity larger than 20 000 Ω·cm. Even–odd mode analysis (EOA) has been performed to extract the currents of the two modes. The embedding impedance of the designed LC‐FDAs has been simulated using conventional numerical electromagnetics, and the results show that a wide range of impedance values (both real and imaginary parts) can be achieved by changing the antenna geometry. This property makes LC‐FDAs suitable for high‐performance THz detectors in which impedance matching between antennas and devices is desired. From the currents calculated using EOA, the LC‐FDA far‐field radiation patterns, antenna directivity and Gaussian coupling efficiency for different lens structures have been examined using ray‐tracing techniques. Good agreement between calculation results and measurement has been observed demonstrating the effectiveness of the above analysis approach. The single element FDA design has also been explored for use in high‐resolution two‐dimensional THz focal plane arrays by optimising the lens structure and evaluating the off‐axis radiation patterns.
Low‐power ultra‐wide band pulse generator based on a PIN diode
Authors: Fernandes Ricardo Dias , Matos João Nuno , Carvalho Nuno Borges
Published: August 2015

Radio‐frequency identification (RFID) tags (passive kind) are typically not designed to include ultra‐wide band (UWB) pulse generators, but may be in the future. The reason is that the very short pulses produced by the RFID tags could be used to estimate their positions with errors of solely a few centimetres using time difference of arrival techniques. Currently, the method most commonly used to estimate tag positions relies on received signal strengths (less accurate). An UWB pulse generator based on a PIN diode is presented in this study. This pulse generator was designed to produce a positive unipolar pulse for each high‐to‐low transition (1.8 V to 0) it receives at its input. This trigger signal is generated by a microntroller‐based battery‐free RFID tag. The end result is a pulse with an amplitude of ∼300 mV and a duration of slightly <2 ns measured using a 50 Ω load.
Solution to the Klein–Gordon equation for the study of time‐domain waveguide fields and accompanying energetic processes
Authors: Akgun Ozlem , Tretyakov Oleg A.
Published: August 2015

In electromagnetics, power flow and energy densities are associated with time‐varying electromagnetic fields. For time‐harmonic waves, such quadratic characteristics are derived using the complex‐valued spatial forms of field vectors resulting in time‐averaged power flow and energy densities. Hence, the opportunity to study dynamic processes of the quadratic characteristics is lost in the time‐harmonic electromagnetics. To overcome this drawback, the authors consider the problem of a waveform propagation in a hollow waveguide via solving the system of Maxwell's equations with time derivative in an energetic space of ‘real‐valued’ functions. The transverse electric and transverse magnetic modal field components are presented as the products of modal basis elements and the modal amplitudes. The vector basis elements are obtained with required physical dimensions, volt per metre and ampere per metre. Thereby, the modal amplitudes are dimension‐free scalar functions. The system of evolutionary equations for the modal amplitudes is derived and solved explicitly. The Klein–Gordon equation (KGE) plays a central role herein. A novel set of real‐valued solutions to the KGE is obtained and applied for analysis of the energetic processes pertinent to the time‐domain signal propagation. The velocity of transportation of the modal field energy is obtained and energetic exchange between the transverse and longitudinal field components is discussed.
High‐gain end‐fire bow‐tie antenna using artificial dielectric layers
Authors: Dadgarpour Abdolmehdi , Zarghooni Behnam , Virdee Bal S. , Denidni Tayeb A.
Published: August 2015

This study presents a high‐gain bow‐tie antenna for applications in next generation base‐stations operating from 2.5 to 3.9 GHz. The proposed structure consists of three circular sector patches that are attached laterally to the microstrip feed‐line, which is etched on both sides of the common dielectric substrate to create symmetrical bow‐tie antenna. By loading the antenna with a 2 × 5 array of enhanced end‐coupled split‐ring (EECSR) unit‐cells results in significant enhancement in the antenna gain performance. This is because the EECSR unit‐cells behave as parasitic radiators, which is analogous to Yagi–Uda antennas. The EECSR unit‐cells provide a medium of high effective permittivity that effectively reduces the spacing between parasitic directors. As a consequence, a compact and miniature structure is achieved compared with conventional quasi‐Yagi–Uda planar designs. The dimension of EECSR unit‐cell is 33 × 36 mm2 with inter‐element spacing of 0.075λ0 at 3.5 GHz. A prototype of the antenna was fabricated and its performance was measured to validate the simulation results. The measured peak gain of the antenna with 4 × 5 array of EECSR is 12.65 dBi at 3.73 GHz, constituting a peak gain enhancement of 7.45 dBi in the Worldwide Interoperability for Microwave Access band compared with an equivalent conventional bow‐tie antenna.
Non‐iterative beamforming based on Huygens principle for multistatic ultrawide band radar: application to breast imaging
Authors: Ghavami Navid , Probert Smith Penny , Tiberi Gianluigi , Edwards David , Craddock Ian
Published: August 2015

This study examines the performance of a simple microwave beamforming method using the Huygens scattering principle (called here the Huygens principle method) for detecting breast lesions. The beamforming method is similar to non‐iterative time reversal in that the wave received is propagated back into the material, although differs in its treatment of attenuation. The single pass algorithm does not require a solution to an inverse model, making it computationally efficient and so able to offer a throughput appropriate for clinical use. Its performance is compared with time‐delay beamforming, which may be implemented with similar computational complexity, on a set of phantoms, including a lossy medium, mimicking breast tissue. The method was used to image a commercially fabricated anatomically shaped breast phantom with multiple hidden inclusions mimicking tumours. The procedure was able to identify and localise significant scatterers inside the volume, with only approximate a‐priori knowledge of the dielectric properties of the target object, in spite of its underlying assumption of a single scatterer model.
Dual polarised aperture‐coupled patch antenna using asymmetrical feed
Authors: Fang Qingyuan , Song Lizhong , Jin Ming , Han Yong , Qiao Xiaolin
Published: August 2015

Dual polarised antennas are normally fed by symmetrical feed networks in order to obtain symmetrical radiation patterns for two orthogonal polarisations. In this study, a dual polarised aperture‐coupled patch antenna using asymmetrical feed for X‐band application is proposed. The exploitation of asymmetrical feed structure in exciting dual polarisations turns out to be valid, and is capable of realising symmetrical radiation patterns just as the traditional feed networks have done. Besides, the asymmetrical feed provides a wide impedance bandwidth and high isolation between ports. Key parameters studies and current distributions analysis prove the feasibility of the asymmetrical feed. Both simulated and measured results indicate an impedance bandwidth over 35.2% and the isolation is higher than 30 dB over the entire bandwidth. The cross‐polarisation levels in the E‐ and H‐planes for both polarisations are lower than −20 dB. Moreover, the antenna prototype shows good symmetrical property in radiation patterns for dual polarisations.
Broadband complementary metal‐oxide semiconductor phase shifter with 6‐bit resolution based on all‐pass networks
Authors: Li Hsiao‐Yun , Fu Jia‐Shiang
Published: August 2015

Multi‐stage all‐pass networks can be used to realise broadband phase shifters with low phase error. In this study, single‐stage and two‐stage all‐pass networks with internal switched capacitors are investigated. Potentials and limitations of using the all‐pass networks with internal switched capacitors for phase shifter design are examined. On the basis of the single‐stage and two‐stage all‐pass networks, a fully‐differential digital phase shifter with 6‐bit resolution is designed. The digital phase shifter is implemented using a 0.18‐μm complementary metal‐oxide semiconductor process. The chip area is 2.80 × 1.75 mm2. Measurement results show that minimum root‐mean‐square phase error of 2° is achieved from 2.19 to 2.82 GHz, which translates into a bandwidth (BW) of 25%. The average insertion loss is 14.6 dB at the design frequency of 2.4 GHz. Over the entire BW, the return loss is greater than 9.2 dB and the amplitude error is within ±1 dB.
Analysis of radiation of antennas with a phase‐gradient partially reflective surface
Authors: Moghadas Hamid , Daneshmand Mojgan , Mousavi Pedram
Published: August 2015

This study presents a novel model for understanding the radiation phenomena and calculating the radiation pattern properties of uniform and phase‐gradient partially reflective surface (PRS) antennas. This model is extracted for one‐ and two‐dimensional antennas using array theory along with the dispersion analysis of the unit cells. The model can calculate the main lobe radiation pattern, scan angle and half‐power beamwidth of uniform and phase‐gradient PRSs with broadside, conical or tilted beams with an accuracy better than 5°. Two common PRS unit cell shapes (slotted patch and dipole) are used here.
Co‐located and distributed antenna systems: deployment options for massive multiple‐input–multiple‐output
Authors: Alnajjar Khawla A. , Smith Peter J. , Woodward Graeme K.
Published: August 2015

To evaluate the benefits of distributed arrays in massive multiple‐input–multiple‐output systems, the authors investigate the interaction between linear receivers (maximum ratio combining and zero forcing) and three deployments scenarios: (i) a massive co‐located array at the cell centre; (ii) a massive array clustered at B discrete locations; and (iii) a massive distributed array with a uniform distribution of individual antennas. The authors also study the effect of propagation parameters, system size, correlation and channel estimation error. The authors demonstrate by analysis and simulation that in the absence of any system imperfections, a massive distributed array is preferable. An intermediate deployment such as a massive array clustered at a few discrete locations, can be more practical to implement and more robust to imperfect channel state information. The authors show an example with a 128 antenna deployment where four locations achieves one third of the gains due to a fully distributed array.
Compact coupled‐line balun with complex impedances transformation and high isolation
Authors: Zhang Weiwei , Wu Yongle , Liu Yuanan , Yu Cuiping , Chen Wenhua
Published: August 2015

A planar microstrip circuit is proposed to design a kind of coupled‐line balun with good ports matching and high output‐ports isolation for complex source to complex load impedance transformation. This balun prototype essentially consists of three coupled‐line sections, a tapped open transmission‐line stub (TOTS) on the left‐hand side, and a tapped complex equivalent‐impedance part (TCEP) on the right‐hand side. The TCEP is the key to realise high output isolation and all ports matching. Based on the traditional even‐odd mode technique and the transmission‐line theory, closed‐form mathematical equations for circuit electrical parameters are obtained. To demonstrate this proposed design theory, a practical microstrip coupled‐line balun is designed, simulated and measured to operate at approximately 2 GHz, indicating high isolation and balanced output. Good agreements between the simulated and measured results verify this design.
High‐power and high‐efficiency complementary metal–oxide–semiconductor voltage‐controlled oscillator for automatic dependent surveillance‐broadcast system
Authors: Roy Palash , Dawn Debasis
Published: August 2015

Automatic dependent surveillance‐broadcast (ADS‐B) system requires higher performance, highly reliable, and smaller size, lighter weight and lower cost transceiver. To reduce the size and cost and to increase the manufacturability it is desirable to integrate the whole ADS‐B system into a single‐chip complementary metal–oxide–semiconductor (CMOS) technology platform. Watt level power is required from the ADS‐B transmitter for transmitting the information about aircraft's precise location at larger distances. This study presents CMOS voltage‐controlled oscillator (VCO) circuit, as a part of ADS‐B transmitter, operating at the centre frequency of 978 MHz, delivers the highest output power with the highest efficiency ever reported to the best of authors’ knowledge. The 0.738 mm × 0.606 mm VCO chip fabricated using 0.18 μm CMOS technology, exhibits the single‐ended peak output power of −0.46 dBm and the differential peak output power of 2.54 dBm at the frequency of 1 GHz, with the frequency tuning range from 954.3 to 1009.4 MHz and phase noise of −109 dBc/Hz at 1 MHz offset centred at the frequency of 978 MHz, consuming 19 mW power from 1.8 V supply, thus, showing state‐of‐the‐art‐performances. This promising result shows a path towards realising high‐power single‐chip CMOS ADS‐B transmitter.
Miniaturised design of coplanar waveguide‐fed broadband circularly polarised slot antenna
Authors: Luo Kang , Chen Bin , Yi Yun , Wang Yigang
Published: August 2015

A novel miniaturised design of broadband circularly polarised (CP) antenna using a coplanar waveguide feed is presented. To realise CP characteristic, a pair of inverted‐L strips around two opposite corners of the slot is protruded. By properly folding the modified ground plane, the 3‐dB axial‐ratio (AR) band is shifted to around a lower‐frequency location, whereas the input impedance band is shifted downwards through the Y‐shaped loading strip. The overall size of the antenna is about 0.34 λ0 × 0.34 λ0 × 0.009 λ0 at 1.7 GHz. Measured results show that the proposed design can deliver 3‐dB AR bandwidth of 36.8% (1.55–2.25 GHz) and 10 dB impedance bandwidth of 63.2% (1.17–2.25 GHz).
Miniaturised antenna design with crossed‐field elements to radiate strong electromagnetic fields for near‐field communications
Authors: Chou Hsi‐Tseng , Yan Yu‐Ting
Published: August 2015

Near‐field (NF) communications require strong energy coupling between transmitting and receiving antennas. An antenna design methodology is thus proposed to design the reader antennas that radiate strong evanescent fields in the vicinity of antenna with good radiation efficiency. This concept employs a pair of radiating elements with approximately conjugated input impedances in nature that have large reactance such that the energy will reside in the NF region. In addition, the orientations of the antenna pair are adjusted to form the relationship of crossed‐fields in the electric and magnetic field components such that the relationship in Poynting vector can be established in the near zone. Both numerical and experimental results based on an antenna design example for the radio frequency identifications applications are presented to validate the concept.
Design strategy of concurrent multi‐band Doherty power amplifier
Authors: Kalyan Robin , Rawat Karun , Koul Shiban Kishan
Published: August 2015

This paper proposes design methodologies of concurrent multi‐band Doherty power amplifiers (PAs) based on multi‐band impedance inverting networks and multi‐band phase offset lines (POLs). Design procedures for implementing such multi‐band impedance inverting networks and multi‐band POLs at arbitrary frequencies are presented here. For validating the design procedures, tri/quad‐band Doherty PAs are designed, fabricated and tested using continuous wave (CW) and modulated signals in discrete mode and concurrent mode. The tri‐band Doherty power amplifier (DPA) is implemented at 1600, 1900 and 2200 MHz. CW signal measurement of tri‐band DPA shows an efficiency of 46%, 40% and 42%, respectively, around 6 dB output power back‐off (OPBO). The quad‐band DPA is implemented at 1600, 1960, 2140 and 2350 MHz. Measured results using CW signal shows an efficiency of 40%, 37%, 30% and 31%, respectively, around 6 dB OPBO.
Single‐pole double‐throw switchable diplexer and single‐pole quadruple‐throw switchable quadplexer using capacitively loaded multicoupled line
Authors: Chen Chang‐Sheng , Lin Yo‐Shen
Published: August 2015

Compact switchable diplexer and quadplexer are proposed using the capacitively loaded multicoupled line and the common resonator technique. The proposed single‐pole double‐throw (SPDT) switchable diplexer integrates the functions of SPDT radio frequency switch and bandpass filter, and each signal path can be independently synthesised using the insertion loss method. In addition, by a simple modification to the common resonator, a single‐pole quadruple‐throw switchable quadplexer can be achieved by the connection of two proposed SPDT switchable diplexers. Low‐loss, compact size, good selectivity, and high‐linearity are achieved.
Binary inheritance learning particle swarm optimisation and its application in thinned antenna array synthesis with the minimum sidelobe level
Authors: Liu Dong , Jiang Qilong , Chen Jim X.
Published: August 2015

Although particle swarm optimisation (PSO) algorithm is an effective tool to solve the real‐number optimisation problem, it cannot be directly adopted to the discrete optimisation. Many discrete PSO versions focused on the different discrete strategies on particle position and speed update equation, but these attempts decreased the performance of the PSO on discrete problems (compared with other intelligent optimisation algorithms). In this study, binary inheritance learning PSO (BILPSO) is proposed and is used to solve thinned antenna array synthesis problems, such as the pattern synthesis of 100‐element symmetrical thinned linear array and 20 × 10 symmetrical thinned planar array. The optimisation results show the BILPSO is superior to other discrete PSO versions and other discrete intelligent optimisation algorithms.
Design of shorted parasitic rhombic array antenna for 24 GHz rear and side detection system
Authors: Shin Dong‐Hun , Park Seong‐Jin , Ahn Jae‐We , Han Ki‐Woong , Park Seong‐Ook
Published: August 2015

A novel microstrip patch antenna is proposed for automotive application. The antenna design has been investigated through both the parametric study and the demonstration of surface currents on the antenna structure. The surface currents related to the co‐polarisation increased, and those related to the cross‐polarisation is reduced by attaching shorted parasitic element. The four types of single antenna are designed to compare of gain and cross‐polarisation level. The cross‐polarisation level of proposed antenna has been reduced by 5.9 dB compared with the rhombic antenna. The rhombic array antenna and proposed array antenna were fabricated and tested for input reflection coefficient and radiation performance. The measured and simulated results have been presented and discussed.
Reflector antenna analysis method using Poynting vector tracing between virtual apertures
Authors: Bai Ming , Ou Naiming , Jin Ming , Miao Jungang
Published: August 2015

In this study, a highly efficient calculation method for analysing electrically large reflector antennas is presented. This method utilises fast Fourier transform enhanced direct integration to calculate beam propagation between parallel virtual apertures, and a novel Poynting vector tracing technique is introduced to treat wave reflections by arbitrary curved surface. Two virtual apertures are set perpendicular to the incident and reflected optical paths. As the centres of the virtual aperture planes coincide with the reflector surface, it makes the ray‐tracing paths between the virtual apertures along with the reflector as short as possible. Owing to these innovative treatments, this method offers a high calculation accuracy comparable with classic physical optics (PO), but with much higher efficiency. By performing numerical comparisons with method of moments, PO algorithm implemented with commercial software FEKO and general reflector antenna software package, the advantages of the proposed method are presented in this study. The method proves to be applicable for the analysis of electrically large reflector antennas.
Enhanced dual‐circular polarised four‐arm Archimedean spiral antenna with low‐profile cavity backing
Authors: Fang Hongzhao Ray , Serhir Mohammed , Guinvarc'h Régis , Mouthaan Koen
Published: August 2015

A wideband dual‐circular unidirectional four‐arm Archimedean spiral antenna operating from 0.6 to 2.4 GHz is presented. Without a cavity, the antenna radiates bi‐directionally and the dual‐circular polarisation of the spiral antenna at boresight is limited to a frequency range from 0.6 to 1.5 GHz. After adding a low‐profile, 15 mm deep metallic cavity, the dual‐circular polarisation at boresight is extended to more than 2.4 GHz and uni‐directional radiation is realised. The four‐arm spiral antenna is excited through a feed network consisting of a wideband four‐way power divider and four wideband digital 2‐bit phase shifters. This feed network facilitates instantaneous switching between right hand circular polarisation and left hand circular polarisation. The measured input return loss of the system is more than 10 dB for the entire two‐octave bandwidth. The measured boresight gain from 0.6 to 2.4 GHz is −2.8 to 11.2 dBi and −3.1 to 8.7 dBi for RHCP and LHCP, respectively.
Multi‐output stacked class‐E millimetre‐wave power amplifiers in 45 nm silicon‐on‐insulator metal–oxide–semiconductor: theory and implementation
Authors: Chakrabarti Anandaroop , Krishnaswamy Harish
Published: August 2015

Series stacking of multiple devices in power amplifiers is a promising technique that has been explored recently at millimetre‐wave frequencies to overcome some of the fundamental limitations of metal–oxide–semiconductor (CMOS) technology. Stacking multiple devices improve the output power and efficiency by increasing the achievable output voltage swing. Switching power amplifiers (PAs), such as Class‐E PAs, are capable of high efficiency operation and can benefit from device stacking. This study presents a new topology for stacked Class‐E‐like PAs. In this technique, an appropriate Class‐E load network is used for each stacked device, which imparts a true Class‐E behaviour to all the devices in the stack. In addition, output power is available from multiple corresponding output nodes. The resulting topology is called the multi‐output stacked Class‐E PA. Two Q‐band prototypes – a unit cell with two devices stacked, and a power‐combined version employing two such unit cells – have been fabricated in IBM's 45 nm silicon‐on‐insulator CMOS technology using the 56 nm body‐contacted devices. Measurements yield a peak PAE of 25.5% for the unit cell with saturated output power of 17.9 dBm, and a peak PAE >16% for the power‐combined version with saturated output power >19.1 dBm. Owing to the proposed technique, the performance metrics are at par with the current state‐of‐the‐art despite the higher ON‐resistance and poor fmax of the body‐contacted devices.
Substrate integrated waveguide bandstop filter using partial‐height via‐hole resonators in thick substrate
Authors: Esmaeili Mahbubeh , Bornemann Jens , Krauss Peter
Published: August 2015

A substrate integrated waveguide (SIW) bandstop filter on thick substrate is introduced. The increased substrate height permits partial‐height via holes to act as resonators whose interaction provides a wide range of possible coupling coefficients that result in wideband bandstop filters. In contrast to ridged all‐metal waveguide filters, SIW filters with partial‐height via holes maintain a small profile, low manufacturing cost and they can be integrated with other planar circuitry such as microstrip or coplanar waveguide. The design method of the bandstop filter relies on the well‐known extracted‐pole technique which allows designers to independently control the locations of reflection zeros. The parameters of the lowpass equivalent circuit of the filter are extracted and used for the initial design of the physical dimensions of the filter. The software packages µWave Wizard and CST are used for filter simulation and optimisation. A prototype bandstop filter is designed for a centre frequency of 10.74 GHz and a bandwidth of 1.58 GHz. Tolerance analyses demonstrate the influence of manufacturing inaccuracies on the filter performance. Good agreement between simulated and measured results confirms the reliability and robustness of the design method and its applicability to SIW technology on thick substrate.
Compact coplanar waveguide‐fed wideband circular polarised antenna for navigation and wireless applications
Authors: Kushwaha Nagendra , Kumar Raj
Published: August 2015

In this study, a new compact coplanar waveguide‐fed wideband circularly polarised slot antenna is designed and fabricated. To achieve circular polarisation, the slot in the ground plane is truncated at one corner and excited by a modified L‐shaped radiating element. To achieve wide axial ratio bandwidth (ARBW), one end of the L‐shaped patch is connected with the ground via a slit. The ARBW is further improved by properly placing two additional narrow slots in the ground plane. The measured impedance bandwidth and ARBW at boresight are achieved 87.2% (from 2.2 to 5.6 GHz) and 81.05% (from 2.2 to 5.2 GHz), respectively. For the better understanding, the surface current distribution and parametric studies are presented. To characterise the antenna in the time domain, group delay and system fidelity factor (SFF) are measured. The measured group delay has less variation (of 0.5 ns) in the operating band and the measured SFF is found to be 0.89. The measured and simulated results are in good agreement.
Modified output impedance matching solution for load modulation power amplifier performance enhancing
Authors: Peng Yatao , Zhang Lijun , Fu Jun , Wang Yudong , Leng Yongqing
Published: August 2015

In this study, a modified load‐modulated power amplifier (LMPA) structure is presented. Unlike the traditional LMPA (Doherty power amplifier) with quarter‐wave line transformers, in this presented LMPA, the two‐point matching network for the main amplifier and two‐side matching network for the auxiliary amplifier are applied to achieve the back‐off efficiency enhancing. The matching networks of the traditional DPAs are analysed and their limiting conditions to achieve optimal performance at back‐off and peak power are deduced. A pre‐matching is added to transform the load impedance (50 Ω) to complex impedance, then more freedom degrees are introduced to design the two point matching network, which results in the conditions for achieving optimal performance are more relaxed. In this way, the max output power at peak power and the optimal efficiency power at back‐off can be achieved for the LMPA simultaneously. To verify the structure, an example LMPA base on GaN devices is designed. The measured max output power is about 43.8 dBm with drain efficiency (DE) of 64.9%. The measured 6 dB back‐off DE is 54.9% and 4.5 dB back‐off efficiency is 60.1%, which is about 15.2% higher than the class AB power amplifier.
One‐step leapfrog weakly conditionally stable finite‐difference time‐domain method for body of revolution
Authors: Wang Yi‐Gang , Yi Yun , Chen Bin , Chen Hai‐Lin , Luo Kang
Published: August 2015

In this study, a novel one‐step leapfrog weakly conditionally stable finite‐difference time‐domain (WCS‐FDTD) method for body of revolution (BOR) is presented. The singularity of some field components on and adjacent to the axis are solved specially, in accordance with the one‐step leapfrog WCS‐FDTD scheme. The electric and magnetic fields of the proposed method are interlaced half a time step apart and no sub‐time steps are used. The novel method obtains a higher computational efficiency while preserving the properties of the conventional WCS‐BOR‐FDTD method. Its stability condition and dispersion error are presented analytically. Moreover, two numerical examples are given to demonstrate the proposed method.