Showing papers on "Decoupling (electronics) published in 2018"

A Review of Mutual Coupling in MIMO Systems

Abstract: This paper provides a systematic review of the mutual coupling in multiple-input multiple-output (MIMO) systems, including the effects on performances of MIMO systems and various decoupling techniques. The mutual coupling changes the antenna characteristics in an array, and therefore, degrades the system performance of the MIMO system and causes the spectral regrowth. Although the system performance can be partially improved by calibrating out the mutual coupling in the digital domain, it is more effective to use decoupling techniques (from the antenna point) to overcome the mutual coupling effects. Some popular decoupling techniques for MIMO systems (especially for massive MIMO base station antennas) are also presented.

Demonstration of Fidelity Improvement Using Dynamical Decoupling with Superconducting Qubits.

Abstract: Quantum computers must be able to function in the presence of decoherence. The simplest strategy for decoherence reduction is dynamical decoupling (DD), which requires no encoding overhead and works by converting quantum gates into decoupling pulses. Here, using the IBM and Rigetti platforms, we demonstrate that the DD method is suitable for implementation in today's relatively noisy and small-scale cloud-based quantum computers. Using DD, we achieve substantial fidelity gains relative to unprotected, free evolution of individual superconducting transmon qubits. To a lesser degree, DD is also capable of protecting entangled two-qubit states. We show that dephasing and spontaneous emission errors are dominant in these systems, and that different DD sequences are capable of mitigating both effects. Unlike previous work demonstrating the use of quantum error correcting codes on the same platforms, we make no use of postselection and hence report unconditional fidelity improvements against natural decoherence.

Decoupling of Inverted-F Antennas With High-Order Modes of Ground Plane for 5G Mobile MIMO Platform

Abstract: This paper presents a novel method of decoupling inverted-F antennas (IFAs) with high-order modes of a ground plane in 5G mobile multiple-input multiple-output (MIMO) platform. The proposed method is illustrated in a dual-antenna 5G mobile platform operating at 3.5 GHz. An IFA excites a high-order mode of the field distribution in the ground plane at 3.5 GHz. The electric field of the excited high-order mode forms several stable null-amplitude field points located on the edge of the ground plane. The other IFA is then placed in one of the stable null points. By doing this, the two IFAs are decoupled with high isolation. The simulated results show that isolation improvements of 20–40 dB can be achieved when the positions and orientations of the two IFAs are optimized. The measured results confirm that the fabricated antennas have peak isolations of 45–56 dB. Finally, the proposed method is applied to design a three-IFA-based MIMO platform which verifies that the suggested concept can effectively simplify the decoupling mechanism and works well in a multiantenna-based mobile MIMO terminal.

Special Section: The Transformative Value of Cloud Computing: A Decoupling, Platformization, and Recombination Theoretical Framework

Abstract: Cloud computing is an evolution of computer technology and a dominant business model for delivering information technology (IT) infrastructure, components, and applications. With cloud computing, a...

A High-Pass Antenna Interference Cancellation Chip for Mutual Coupling Reduction of Antennas in Contiguous Frequency Bands

Abstract: In this paper, an antenna interference cancellation chip (AICC) with a high-pass response is proposed to mitigate the mutual coupling of two antennas resonating in contiguous frequency bands. Using the most up-to-date low temperature co-fired ceramic (LTCC) technology, the chip only occupies a compact volume of $1.6\times 0.8\times 0.6$ mm3. Two external tuning capacitors and two shunt inductors together with the LTCC AICC device which are in shunt with two coupled antennas, are able to improve the antenna isolation near band-edge by more than 15 dB without sacrificing antenna performance in its useful resonating bands. The high-pass property of the AICC device prevents the decoupling design near 2.4GHz affecting the successful operation of GPS at 1.575 GHz. The superiority of the proposed method is verified with active measurement of a Mi-Fi (mobile Wi-Fi) device in Wi-Fi hotspot mode using the AICC device. The proposed AICC device and corresponding decoupling method with the device can find plenty of applications in long-term-evolution and future 5G wireless platforms.

A Meta-Surface Antenna Array Decoupling (MAAD) Method for Mutual Coupling Reduction in a MIMO Antenna System

Abstract: In this paper, a method to reduce the inevitable mutual coupling between antennas in an extremely closely spaced two-element MIMO antenna array is proposed. A suspended meta-surface composed periodic square split ring resonators (SRRs) is placed above the antenna array for decoupling. The meta-surface is equivalent to a negative permeability medium, along which wave propagation is rejected. By properly designing the rejection frequency band of the SRR unit, the mutual coupling between the antenna elements in the MIMO antenna system can be significantly reduced. Two prototypes of microstrip antenna arrays at 5.8 GHz band with and without the metasurface have been fabricated and measured. The matching bandwidths of antennas with reflection coefficient smaller than −15 dB for the arrays without and with the metasurface are 360 MHz and 900 MHz respectively. Using the meta-surface, the isolation between elements is increased from around 8 dB to more than 27 dB within the band of interest. Meanwhile, the total efficiency and peak gain of each element, the envelope correlation coefficient (ECC) between the two elements are also improved by considerable amounts. All the results demonstrate that the proposed method is very efficient for enhancing the performance of MIMO antenna arrays.

Novel Pattern-Diversity-Based Decoupling Method and Its Application to Multielement MIMO Antenna

Abstract: In this paper, a novel decoupling method without adding any decoupling structure is investigated, and it is able to apply to multiple-input and multiple-output (MIMO) antenna designs with dual and multiple elements. The decoupling mechanism applied in here is to change the electrical length of the radiators to manipulate the radiation pattern for obtaining pattern diversity and good isolation simultaneously. The design mechanism and procedures for realizing pattern diversity are presented. To validate the proposed method, a two-element monopole antenna array with inverted-L elements is initially studied with the isolation better than 20 dB. Next, a four-element MIMO antenna utilizing two different types of monopole elements is proposed to further verify the feasibility of the proposed decoupling method. Finally, an eight-element MIMO antenna operating at 3.5 GHz is implemented with a compact total size of $40\times 100$ mm2, and the measured isolations between two elements are better than 15 dB. Envelope correlation coefficient and channel capacity are calculated to evaluate the MIMO performance, and good results are obtained. The target application of the proposed design is for laptop, small cell base station, or WiFi box with multiple elements.

He 3 - Xe 129 Comagnetometery using Rb 87 Detection and Decoupling

Abstract: An enhanced version of a magnetometer based on atomic spins could be used to search for theoretically predicted exotic fields with ultrahigh sensitivity.

Decoupling electron and ion storage and the path from interfacial storage to artificial electrodes

Abstract: The requirements for rechargeable batteries place high demands on the electrodes. Efficient storage means accommodating both ions and electrons, not only in substantial amounts, but also with substantial velocities. The materials’ space could be largely extended by decoupling the roles of ions and electrons such that transport and accommodation of ions take place in one phase of a composite, and transport and accommodation of electrons in the other phase. Here we discuss this synergistic concept being equally applicable for positive and negative electrodes along with examples from the literature for Li-based and Ag-based cells. Not only does the concept have the potential to mitigate the trade-off between power density and energy density, it also enables a generalized view of bulk and interfacial storage as necessary for nanocrystals. It furthermore allows for testable predictions of heterogeneous storage in passivation layers, dependence of transfer resistance on the state of charge, or heterogeneous storage of hydrogen at appropriate contacts. We also present an outlook on constructing artificial mixed-conductor electrodes that have the potential to achieve both high energy density and high power density. Electrochemical storage is typically accompanied by simultaneous accommodation of ions and electrons. Here the authors discuss a concept of decoupling electron and ion storage and present their perspectives of constructing artificial mixed conductor electrodes to enhance storage ability.

Self-Curing Decoupling Technique for Two Inverted-F Antennas With Capacitive Loads

Abstract: A new concept named the self-curing decoupling technique is proposed for the first time to reduce the mutual coupling between two closely located inverted-F antennas (IFAs). The decoupling technique only requires a capacitive load on the shorting arm of each coupled IFA without connecting a circuitry or inserting a physical structure between the two coupled antennas. The capacitive load occupies very little space and is frequency-insensitive; therefore, the decoupling technique is a very favorable choice for low-frequency applications. Network analysis is presented to mathematically justify the working mechanism and to provide a design guideline. Several practical cases of two IFAs situated at different positions on the periphery of a PCB board are studied. The experimental results show that with the decoupling technique, significant improvements in the port isolation (from 10 to 20 dB), antenna correlation coefficient (from 0.25 to 0.05), multiplexing efficiency (from 46% to 60%), and above all the system throughput (1.2 and 0.8 dB power saving in Urban Microcell and Urban Macrocell channels, respectively) can be obtained.

Mutual coupling reduction with a wideband planar decoupling structure for UWB–MIMO antennas

Abstract: A new planar multiple-input–multiple-output (MIMO) antenna for ultra wideband (UWB) applications is presented. The proposed antenna operates over the frequency band from 3.1 to 10.6 GHz and it consists of two identical circular monopoles on an FR4 substrate. The wide isolation is achieved through a novel planar decoupling structure that is being inserted between the dual antennas. Moreover, a center slot is etched on the common ground to further increase isolation. The effectiveness of the decoupling structure is analyzed, and performance study has been performed to investigate the mutual coupling reduction. A good isolation of more than 31 dB has been achieved through the entire UWB band (more than 12 dB improvement over the reference antenna). The proposed UWB antenna with and without the wideband decoupling structure has been investigated and verified both numerically and experimentally. The measurement results of the proposed UWB–MIMO antenna are in good agreement with the simulation results. The proposed UWB antenna has been compared with previous works regarding antenna size, geometric complexity, bandwidth, and isolation level. The proposed antenna has some outstanding characteristics such as a geometric simplicity, compact size, broad bandwidth, and low correlation which give the antenna an excellent diversity performance and a good candidate for UWB applications.

Hybrid Fuzzy Decoupling Control for a Precision Maglev Motion System

Abstract: This paper presents a hybrid fuzzy decoupling control strategy, and its implementation for leveling and positioning a maglev wafer carrier in an integrated circuit (IC) packaging application. The maglev platform possesses micron scale positioning and can carry the wafers with precision motion between workstations. Because the maglev system is open-loop unstable, there are strong nonlinear interactions between electromagnets and the exact nonlinear system model is unknown, it is hard to achieve a good decoupling control performance by using conventional control strategy. Therefore, in this paper, a hybrid fuzzy decoupling control with good decoupling performance is proposed. The decoupling control uses a master–slave structure, which consists of a linear master decoupling control term and a nonlinear slave intelligent compensation term. The master decoupling term decouples the main interactions of the coupled maglev system. Using the decoupled main system as reference, the slave intelligent term compensates the nonlinear interactions. Furthermore, for this control strategy, establishing the exact linear or nonlinear model is not necessary, only an approximated linear model is needed. The experimental results show that the proposed control strategy decouples most of the interactions between the electromagnetic actuators. Experimental comparisons also highlight that the master–slave decoupling control has shorter settling time and smaller steady-state error than a conventional adaptive fuzzy controller and proportional-integral-differential controller.

Decoupling Compensation for Damping Improvement of the Electrohydraulic Control System With Multiple Actuators

Abstract: This paper proposes a decoupling compensation method for damping improvement of the electrohydraulic control system with multiple actuators. The low damping property of hydraulic systems has been a remarkably troublesome issue for a few decades. Previously, this issue with one actuator has been addressed effectively by state feedback and signal compensation, e.g., dynamic pressure feedback. However, the poor damping with multiple actuators is still intractable and pendent due to the complex coupling effect of different loads. A decoupling compensator based on pump/valve combined control is proposed for a typical electrohydraulic system with multiple actuators for mobile machinery. Using decoupling control of different load branches, the coupling hydraulic circuit with multiple cylinders is transformed into multiple separate single-cylinder circuits with dynamic compensation. The dynamic characteristics of different actuators are then improved synchronously without mutual interference, while the steady performance remains the same without loss of controllability. Compound motion tests on a 2-ton hydraulic excavator were carried out. The results showed that the proposed compensator reduced velocity and pressure oscillations under different working conditions, so the dynamic performance is improved for the multiactuator system.

Decoupling of Climatic Drying and Asian Dust Export During the Holocene

Abstract: Both paleoclimatic records and models suggest that the dust accumulation in ice cores and marine sediments, which is often regarded as a direct record of changing atmospheric dust loading and used to estimate its climatic impact, is strongly coupled to the aridity of dust source regions. However, the underlying association of this couple has not been tested directly because of the lack of continuous and well-dated independent records of eolian activity in dust source regions. Here we present a high-resolution multiproxy record of the Holocene eolian activity and climate changes from Lake Xiarinur in north China, a major Asian dust source region. Our data, together with the records of Asian dust accumulation in downwind areas, including the North Pacific Ocean and Greenland, suggest a decoupling between long-distant Asian dust export and climatic drying in the Holocene. Although the climate was humid and the eolian activity was weak in the source region during the early Holocene, the dust accumulation in the North Pacific Ocean and Greenland was relatively high. Similarly, while climatic drying and strong eolian activity occurred in north China during the late Holocene, the rate of dust accumulation in the downwind areas was low. The long-distant export of Asian dust is closely correlated with the strength of the Siberian High rather than the westerlies as widely believed before. The rate of dust accumulation in the GISP2 Greenland ice core is comparable in patterns with the intensity of the Siberian High forced eolian activity on both millennial and centennial time scales. Plain Language Summary Scientific grounds: We bring new, uniquely indicative evidence to bear on the dynamics of long-distant Asian dust exports. By uniting the evidences of Holocene aeolain activity and climate changes in north China, dust accumulation in Northwest Pacific Ocean and Greenland ice, the atmospheric circulations dominated Asian dust export, we confirm a central role of the Siberian High in long-range Asian dust export, rather than climate drying and the westerlies as most previous studies suggested. These results have important implications for both accurately estimating aerosol climate forcing and predicting future impact of atmospheric dust concentration changes with climate changes. Popular appeal: Our work also provides important insight into the climatic and environmental impact of anthropogenic aerosols, an important issue of international broad interest. The central role of the atmospheric circulations in long-range Asian dust export, combined with comparisons between the environment with heavy and that without or little human interference in the Holocene, indicate that the anthropogenic activity would contribute little to the long-range Asian dust export without strong atmospheric circulations. Therefore, modern Asian anthropogenic pollutant aerosols would be poorly dispersed from the source regions, otherwise transported across the whole global.

On Stokes--Ritz Projection and Multistep Backward Differentiation Schemes in Decoupling the Stokes--Darcy Model

Abstract: We analyze a parallel, noniterative, multiphysics domain decomposition method for decoupling the Stokes--Darcy model with multistep backward differentiation schemes for the time discretization and ...

Moving to a Low-Carbon Economy in China: Decoupling and Decomposition Analysis of Emission and Economy from a Sector Perspective

Abstract: Understanding decoupling China’s emissions from the economy and identifying the drivers of emissions at a sector perspective can facilitate China’s move to a low-carbon economy that makes economic growth compatible with carbon reduction. This study combined decoupling and decomposition econometric techniques to quantify both the decoupling effects and the driving elements of carbon emissions in China’s six major sectors. The study found that the leading source of all carbon emissions in China come from the industrial sector, followed by the ‘Other’ sectors and the Transport sector. Further, the decoupling status in those sectors differed: Construction (weak decoupling), other (weak decoupling), Trade (weak decoupling), Industry (weak decoupling), Transport (expansive coupling) and Agriculture (expansive negative decoupling). Finally, the economic output effect becomes the major contributor for carbon emissions among these six sectors, followed by the energy intensity effect. However, the energy structure effect and carbon coefficient effect are both weak.

Decoupling Network Design for Inner Current Loops of Stand-Alone Brushless Doubly Fed Induction Generation Power System

Abstract: Brushless doubly fed induction generator (BDFIG) is of high reliability due to its brushless structure. However, brushless structure also results in the complicated d–q vector model, in which the d and q channels are seriously coupled. Traditionally many feedforward (FF) terms were added during control for decoupling purpose. However the FF method features several drawbacks: 1) it requires extra sensors; 2) the rotor position information needs to be known for d–q transformation; and 3) the decoupling effect highly depends on the parameter accuracy. To overcome these problems, this letter proposes a decoupling method based on the decoupling network (DN). With DN method, the BDFIG and the load are first modeled as a dual-input-dual-output system, and then the DN is designed. From control point of view, the DN is in series with the BDFIG and the load, and thus, form a new control plant with highly decoupling feature. As a result, the controllers in d and q channels can be easily designed. The proposed DN method requires neither extra sensors nor rotor position information, and the robustness is enhanced since parameter variations of BDFIG and load can be fully considered during DN design. In this letter, such a DN method is presented and applied on the inner current loops of a stand-alone BDFIG system to obtain the good decoupling feature in the overall operational range, and the design results are verified by the experiments from a stand-alone BDFIG system platform.

Direct Instantaneous Ripple Power Predictive Control for Active Ripple Decoupling of Single-Phase Inverter

Abstract: Active ripple decoupling technique of the single-phase inverter is a popular topic to minimize the dc-link capacitance. However, the existing control methods are based on tracking sinusoidal or predetermined voltage waveforms of the compensation capacitor, assuming the inverter outputs are pure sinusoidal voltage and current. Therefore, the performance of existing methods degrades when the inverter output voltage and current are not purely sinusoidal. Furthermore, the limited dynamic performance threatens the safety of dc-link capacitor when the load changes. This happens, because the inrush ripple power is injected into dc link with small capacitance and the dc-link voltage will suddenly rise up when the ripple power is not buffered during transients. In this paper, a direct instantaneous power predictive control is proposed for the decoupling circuit to buffer ripple power of the single-phase inverter, which combines instantaneous ripple power control with model predictive control to overcome the issues above. The proposed method tracks the instantaneous ripple power rather than voltage or current waveforms. In this way, it can fully buffer all ripple powers in the system even for distorted output voltage and current of the inverter and enables the full utilization of storage capacitor. In addition, model predictive control makes the proposed method have fast dynamic and perfectly compensate ripple power during transients and steady states. The buck-type active ripple decoupling circuit is chosen to implement the proposed method after comparing with another typical decoupling topology. The proposed method is also compared with conventional method using proportional-integral-resonant regulator to track the predetermined capacitor voltage waveform. Experimental tests verify the theoretical analysis and the proposed control method.

Design of an Antenna Decoupling Structure for an Inband Full-Duplex Collinear Dipole Array

Abstract: Single-frequency full-duplex (SFD) wireless communication can increase the efficiency of bandwidth utilization by ideally doubling the spectral efficiency. SFD can be achieved by reducing the level of the self-interference between the transmitter (TX) and receiver (RX) to the RX noise floor. This communication describes a novel decoupling structure to increase the isolation for a collinear dipole array which retains the omnidirectional radiation patterns of the dipole antennas. The structure is based on a parasitic element which couples power from the TX antenna and reradiates it with orthogonal polarized elements canceling the original field around the RX antenna. A novel analysis is presented for the decoupling structure in which the phase and amplitude radiation pattern of the decoupling structure is calculated. The obtained isolation is more than 50 dB according to the simulation and measurement results for a bandwidth of 11%, fulfilling the required electromagnetic isolation for a full-duplex system in indoor device-to-device communications.

Isolation Enhancement in Dual-Band Microstrip Antenna Array Using Asymmetric Loop Resonator

Abstract: This letter presents the design of a wideband decoupling element for mutual coupling reduction in microstrip antenna arrays. The proposed decoupling unit cell consists of an asymmetric loop resonator with a coupled microstrip line for wide stopband characteristics from 2 to 5 GHz. The bandgap characteristic of the decoupling element is analyzed, and the results are presented. Furthermore, the resonator is deployed in a two-element dual-band microstrip antenna array, and mutual coupling reduction is demonstrated. The decoupling unit cell has a lateral dimension of 2.84 mm and hence enables the packing of antenna elements in very close proximity with reduced mutual coupling. The proposed solution offers additional isolation greater than 15 dB in a V-slot loaded dual-band antenna with edge-to-edge element spacing of ${\text{0.057}}\,\lambda _{o}$ . The prototype dual-band antenna array with decoupling element is fabricated, and the simulation results are validated using experimental measurements.

A Novel Dual-Band Decoupling and Matching Technique for Asymmetric Antenna Arrays

Abstract: A novel dual-band decoupling and matching technique for asymmetric two-element antenna arrays is proposed. Decoupling and matching at two widely separated frequencies is accomplished by using a two-layer (level) network approach. Unlike previous works, analytical solution is readily available and prematching of the radiating elements is no longer required. Simulation and experimental results show that the proposed method can offer improved port isolation and input return loss, enhanced efficiency, and increased radiation pattern diversity in both frequency bands.