Tunable Capacitors Research Articles

Optimal Capacitance Design for IRS Aided Wireless Power Transfer for Sustainable IoT Communication

ABSTRACTIntelligent reflecting surface (IRS) is a cutting‐edge technique that can significantly improve wireless propagation. It can efficiently utilize wireless power transfer to enable sustainable Internet‐of‐Things (IoT) transmission by reconfiguring the incident signal from the active transmitter. However, the flexibility of capacitance tuning in the IRS system, which controls underlying reflections, is often overlooked. The effective capacitance design in the IRS system can provide a new degree of freedom in the IoT communication system, which can enable additional performance gain in the received power. To achieve this, a novel IRS circuital optimization model is proposed in this work. It incorporates various electrical parameters of the meta‐surface unit cell for improved IoT‐enabled communication. The proposed optimization model provides an optimal capacitance as a function of phase shift (PS), which is controlled by IRS, incident frequency, and other IRS electrical parameters. This optimal capacitance is then used to define the received power. The convexity of the optimization problem is proved, and the global optimal capacitance is obtained for received power maximization. Our simulations show that the proposed optimization model outperforms the existing constructive interference‐based optimal PS method, for which the capacitance is first calculated. Finally, the analytical results are numerically validated with several optimal design insights.

A high-volume resonator for L-band DNP-NMR

DNP-NMR and EPR experiments that operate at or greater than L-band (i.e., ν0(e−) = 1–2 GHz) are typically limited to maximum sample volumes of several hundred µL. These experiments rely on well-known resonator designs for DNP/EPR irradiation such as the loop-gap resonator and Alderman-Grant coil, where their maximum volumes limit further application to imaging experiments and high-throughput screening beyond L-band. Herein, we demonstrate a birdcage (BC) resonator design that can accommodate several mL of sample while operating around 1.5 GHz. The sample volume is maximized by using two identical BC resonators in a stacked configuration. Simulations are used to optimize the BC design and the performance is validated experimentally with liquid-state Overhauser-DNP-NMR experiments. This BC design exploits just the parasitic capacitance of conductive rings and features no fixed tuning capacitors. An enhancement of −77 is achieved on a 10 mM 4-Amino-TEMPO in H2O sample for a 5 mL sample volume. The associated sample heating is minimal due to the low-E-fields generated and the large sample mass with +3.4 K when driving 100 W for several seconds.

A 1024-Channel Simultaneous Electrophysiological and Electrochemical Neural Recording System with In-Pixel Digitization and Crosstalk Compensation.

Simultaneous electrophysiological and chemical recording allows for multi-modal neural instrumentation and provides insights into chemical synapses and ion channels across the cell membrane. However, intermodal interference can hinder highly synchronized recording in large-scale systems with high temporal and spatial resolution. In this work, we propose a 1024-channel lab-on-CMOS system for dual-modal neural recording with in-pixel digitization and interference suppression. A foreground calibration scheme with tunable capacitance is implemented in-pixel to compensate for the crosstalk between electrical and chemical recording. Active pixels for both electrical and chemical modalities are designed based on a pulse width modulation (PWM) analog-to-digital conversion scheme. CMOS-compatible post-processing is implemented to realize in-pixel electrodes and chemical sensing membranes. The prototype, implemented in a 180nm CMOS technology, occupies a total area of 33mm2 with 1024 pixels, and each unit pixel includes one electrical recording site and two chemical recording sites, with dimensions of 150μm×130 μm. The total system power consumption is 19.68mW at a frame rate of 9k and 3k for electrical and chemical imaging respectively. The in-vitro experiment demonstrated the concurrent high density electrophysilogical and electrochemical recording with sub millisecond temporal resolution.

Droplet-based triboelectric devices using liquid dielectrics for self-powered sensing applications

Triboelectric nanogenerators (TENGs) have attracted great interests by exploiting the complex interplay between contact electrification and electrostatic induction. The versatility of tribo-dielectric materials offers significant advantages for environmentally adaptive device design. In this regard, liquid dielectrics provide intimate contact between filled materials and high dielectric strength. Herein, a liquid dielectric-based TENGs system featuring a charge-transfer liquid layer is presented. A multifaceted summary is presented to illustrate the relationship between liquid dielectric materials and charge transfer mechanisms. New strategies for exploiting the dielectric properties of various liquids to control their electrical properties and monitor the parameters of liquid dielectric properties are highlighted. Additionally, it contributes to the advancement of self-powered sensing technology with increased flexibility, capacitance tuning, and sensor functionality through easy modularization. These achievements contribute to the understanding of charge transfer mechanisms in liquids and highlight their potential for self-powered sensing applications.

Tuning capacitance of bimetallic ZnCo2O4 using anionic, cationic and non-ionic surfactants by hydrothermal synthesis for high-performance asymmetric supercapacitor

Surface properties of nanomaterials are directly related to their electrochemical performance, with surfactants playing an essential role in their cost-effective synthesis as structure-directing agents and templates. This research article discusses the effects of neutral, cationic, and anionic surfactants on the capacitance of bimetallic ZnCo2O4 nanomaterial, synthesized via a straightforward hydrothermal-annealing method. We investigated how cationic (cetyl-trimethyl ammonium bromide), anionic (sodium dodecyl sulphate), and non-ionic (urea) surfactants influence the electrochemical characteristics of ZnCo2O4 nano-powders. All three surfactant-based ZnCo2O4 electrodes exhibited Faradaic behaviour during electrochemical tests. The ionic nature of the surfactants significantly impacted the charge-storage mechanism, with specific capacitance values rising in the order of Urea (550 Fg−1) < C-TAB (740 Fg−1) < SDS (980 Fg−1) at a 1 Ag−1 in half-cell studies. The ZnCo2O4-SDS displayed the highest surface redox reactivity and superior electrochemical performance, with 426 Fg−1 in full-cell studies, energy density of 230 WhKg−1 (1 Ag−1), power density of 18,213.9 WKg−1 (10 Ag−1), and 93 % capacitance retention is observed over 50,000 cycles (50 Ag−1).

Quantum paraelectric varactors for radiofrequency measurements at millikelvin temperatures

Radiofrequency reflectometry can provide fast and sensitive electrical read-out of charge and spin qubits in quantum dot devices coupled to resonant circuits. In situ frequency tuning and impedance matching of the resonator circuit using voltage-tunable capacitors (varactors) is needed to optimize read-out sensitivity, but the performance of conventional semiconductor- and ferroelectric-based varactors degrades substantially in the millikelvin temperature range relevant for solid-state quantum devices. Here we show that strontium titanate and potassium tantalate, materials which can exhibit quantum paraelectric behaviour with large field-tunable permittivity at low temperatures, can be used to make varactors with perfect impedance matching and resonator frequency tuning at 6 mK. We characterize the varactors at 6 mK in terms of their capacitance tunability, dissipative losses and magnetic field insensitivity. We use the quantum paraelectric varactors to optimize the radiofrequency read-out of carbon nanotube quantum dot devices, achieving a charge sensitivity of 4.8 μe Hz−1/2 and a capacitance sensitivity of 0.04 aF Hz−1/2.

A nonlinear piezoelectric shunt absorber with tunable piecewise linear negative capacitance

In recent years, extensive research has been devoted to nonlinear piezoelectric shunt circuits for mitigating structural vibrations. However, existing studies have primarily concentrated on polynomial nonlinearity, particularly cubic nonlinearity. This paper develops a tunable non-smooth piezoelectric shunt absorber to suppress structural vibrations under harmonic excitation. We enhance the conventional resonant circuit by introducing a piecewise linear negative capacitor, which is implemented using a pair of diodes and voltage sources. The stationary response of the non-smooth system is derived using the complexification–averaging method. The effects of critical voltage and excitation intensity on the damping performance are investigated subsequently. Furthermore, we apply an adaptive control method based on the gradient descent algorithm with adaptive moment estimation (Adam) to the nonlinear circuit, improving its damping performance and enabling adaptation to changes in excitation intensity. Experimental results validate the effectiveness of the proposed adaptive nonlinear circuit, demonstrating superior stationary performance compared to linear resonant shunt circuits across a broad bandwidth of frequencies, especially at off-resonant frequencies.

Driving scheme for residual image reduction in active-matrix organic light-emitting diodes display

Residual image is a frequent issue in active-matrix organic light-emitting diode (AMOLED) display, due to hysteresis effects of the internal devices. Up to now, some optimized methods have been researched mainly from process perspective. However, the approaches from driving scheme perspective and their electrical mechanism have rarely been demonstrated systematically. In this work, a technical proposal has been proposed to separate the influences of different devices including both thin film transistors (TFTs) and OLEDs furtherly. It was found that the current curve gap was nearly equal to the luminance curve gap and the main factor of residual image was shown to be the hysteresis of TFTs. An equivalent circuit of two thin film transistors and one capacitor (2T1C) was also adopted to substantiate the influences of threshold voltage (Vth) compensation for reducing residual image, and a series of experiments of tuning capacitance were carried out for corresponding compensation improvements. Moreover, other driving scheme optimizations were also studied to reduce residual image furtherly, including increasing the data input time and resetting the driving TFTs. The research opens the possibility of considering reduction of residual image from driving scheme perspective and more systemic analysis from the internal electrical mechanism in AMOLED display.

A new electrostatic tunable capacitor for wide ranges of applications

A new electrostatic tunable capacitor for wide ranges of applications

Robust Tunability and Newly Emerged Q Resonance of Ba0.8Sr0.2TiO3-Based Microwave Capacitors under Gamma Irradiations.

The complex resonance of dielectric quality factor Q, combined with a capacitance tunability n higher than 3:1 without any dispersion, was achieved in the voltage-tunable interdigital capacitors (IDCs) based on epitaxial Ba0.8Sr0.2TiO3 ferroelectric thin films across the microwave L (1-2 GHz), S (2-4 GHz), and C (4-8 GHz) bands at room temperature. The resonant Q and n features were driven by the microwave responses of the ferroelectric nanodomains engineered in the films. To promote their application in space radiation environments, the evolutions of Q and n both as functions of frequency f (1-8 GHz) and applied electric field E (0-240 kV/cm) were systematically investigated under a series of gamma-ray irradiations up to 100 kGy. The robust capacitance tunability was accompanied by the emergence of an additional Q resonance at 2.3 GHz in most post-irradiated devices, which is ascribed to extra polar nanoregions of expanded surface lattices associated with oxygen vacancies induced by irradiations.

Design of liquid level detection circuit based on sampling probe structure capacitance.

Liquid level detection system is an essential core functional component of automatic clinical medical testing instrument. The conventional liquid level detection method has low detection accuracy and sensitivity, and may have the problem of false detection, which may lead to the inaccurate test results. This paper presents a high sensitivity liquid level detection system based on the principle of variable capacitance. When the sampling probe contacts the liquid level, the probe capacitance will change. The liquid level detection circuit board judges whether the probe contacts the liquid level by sensing the change of probe capacitance. When judging the liquid level signal, the combination of slope detection and amplitude detection is used. The liquid level detection circuit board takes the phase-locked loop(PLL) circuit as the center to detect the change of the capacitance. The reference signal of the PLL is set as a square wave of 375kHz. The double tube probe is used as a part of the tuning capacitor of the voltage controlled oscillator to control the frequency of the output signal, which can realize the rapid phase locking. The experimental results show that the system has accurate detection results, high sensitivity, stable and reliable operation, good dynamic response performance in the case of large and small liquid volume. Compared with other liquid level detection methods based on machine vision, ultrasonic, optics and so on, the proposed liquid level detection system has simpler structure and lower cost, it can avoid the problems of collision, carryover contamination and empty suction by controlling the depth of sampling needle inserted into liquid.

Gyrator-Gain Variable WPT Topology for MC-Unconstrained CC Output Customization Using Simplified Capacitance Tuning

Load-independent constant current (CC) outputs are desirable in many applications of wireless power transfer (WPT). Yet the WPT gain of a conventional system is normally dependent on the magnetic components (MCs) such as coils or inductors, making it difficult to customize the output for interoperability. This paper presents a gain variable WPT topology for CC output customization, which only employs capacitance tuning to provide sufficient freedom in gain regulation. To break the gain limitation of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S-S</i> compensation, which is the simplest with gyrator characteristics for CC output, a capacitive or inductive component is paralleled to the coil as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SP-S</i> or <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S-PS</i> compensation. A thorough analysis based on the Y-Δ transform indicates that the gain is restrictively variable with the parallel component. An <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S-CLC</i> -compensated topology without an independent inductor is further proposed to avoid those restrictions with as few additional components as possible. The inductor in the topology, coupled with the transmitter coil and integrated into the receiver coil, extends the gain variable range. A complete design process of the topology is presented to realize efficient WPT and CC output customization with a wide variable-gain range and misalignment tolerance. Analytical and simulation results confirm the effectiveness of the gyrator-gain variation by capacitance tuning. Finally, the performance of the WPT topology is evaluated by experimental results on a scaled-down prototype.

A Wearable All-Printed Textile-Based 6.78 MHz 15 W-Output Wireless Power Transfer System and Its Screen-Printed Joule Heater Application

While research in passive flexible circuits for Wireless Power Transfer (WPT) such as coils and resonators continues to advance, limitations in their power handling and low efficiency have hindered the realization of efficient all-printed high-power wearable WPT receivers. Here, we propose a screen-printed textile-based 6.78 MHz resonant inductive WPT system using planar inductors with concealed metal-insulator-metal (MIM) tuning capacitors. A printed voltage doubler rectifier based on Silicon Carbide (SiC) diodes is designed and integrated with the coils, showing a power conversion efficiency of 80-90% for 2-40 W inputs over a wide load range. Compared to prior wearable WPT receivers, it offers an order of magnitude improvement in power handling along with higher efficiency (approaching 60%), while using all-printed passives and a compact rectifier. The coils exhibit a simulated Specific Absorption Rate (SAR) under 0.4 W/kg for 25 W received power, and under 21 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C increase in the coils' temperature for a 15 W DC output. Additional fabric shielding is investigated, reducing harmonics emissions by up to 17 dB. We finally demonstrate a wirelessly-powered textile-based carbon-silver Joule heater, capable of reaching up to 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C at 2 cm separation from the transmitter, as a wearable application which can only be wireless-powered using the proposed system.

Design and measurement of a tunable metasurface low-frequency radar absorber

At the turn of the millennium, developments on metasurfaces lead to a significant step forward in the design of radar absorbing structures, especially at lower frequencies, thanks to a reduced thickness. Still, as with other passive impedance matching systems, they remain constrained in their bandwidth-to-thickness ratio. Fortunately, the recent integration of active electronic components onto metasurfaces has multiplied their functionalities, unlocking new ways to overcome these limitations. For instance, using varactor diodes, which act as variable capacitors, an absorbing metasurface can be rendered tunable to cover a frequency range wider than would any passive system of similar thickness. This is a valuable feature when facing modern frequency-hopping radars. However, the bias-dependent resistance introduced by the varactor diodes can compromise the impedance matching throughout the tunable frequency range. This work, therefore, focuses on the design and measurement of a tunable radar absorbing metasurface using varactor diodes, highlighting the necessity for a joint tuning of capacitance and resistance to grant near-perfect absorption over a wide frequency range.

Multi-Stimuli Operando Transmission Electron Microscopy for Two-Terminal Oxide-Based Devices.

The integration of microelectromechanical systems (MEMS)-based chips for in situ transmission electron microscopy (TEM) has emerged as a highly promising technique in the study of nanoelectronic devices within their operational parameters. This innovative approach facilitates the comprehensive exploration of electrical properties resulting from the simultaneous exposure of these devices to a diverse range of stimuli. However, the control of each individual stimulus within the confined environment of an electron microscope is challenging. In this study, we present novel findings on the effect of a multi-stimuli application on the electrical performance of TEM lamella devices. To approximate the leakage current measurements of macroscale electronic devices in TEM lamellae, we have developed a postfocused ion beam (FIB) healing technique. This technique combines dedicated MEMS-based chips and in situ TEM gas cells, enabling biasing experiments under environmental conditions. Notably, our observations reveal a reoxidation process that leads to a decrease in leakage current for SrTiO3-based memristors and BaSrTiO3-based tunable capacitor devices following ion and electron bombardment in oxygen-rich environments. These findings represent a significant step toward the realization of multi-stimuli TEM experiments on metal-insulator-metal devices, offering the potential for further exploration and a deeper understanding of their intricate behavior.

Tunable microstrip bandpass filter with constant absolute bandwidth using BST varactors and digitally tunable capacitors

Abstract In this paper, two second-order electronically tunable bandpass filters are presented. The filters are implemented in microstrip technology using barium–strontium–titanate (BST) varactors and digitally tunable capacitors (DTC) for tuning the frequency response of the bandpass filters. The filter realized using BST varactors has a 35% tuning range from 900 MHz to 1.275 GHz with an insertion loss variation from 3.1 to 2.6 dB. The absolute bandwidth is nearly constant over the entire tuning range, varying from 64 to 72 MHz (around ±5% variation). The filter realized using DTCs also has a 36% tuning range from 850 MHz to 1.225 GHz with an insertion loss variation from 3.1 to 1.5 dB. The absolute bandwidth is constant over the tuning range, varying from 88 to 98 MHz (around ±5% variation). The bandpass filters are tuned using a single control signal. The tunable bandpass filters are proposed for use in reconfigurable radios.

Weld-free mounting of lamellae for electrical biasing operando TEM

Recent advances in microelectromechanical systems (MEMS)-based substrates and sample holders for in situ transmission electron microscopy (TEM) are currently enabling exciting new opportunities for the nanoscale investigation of materials and devices. The ability to perform electrical testing while simultaneously capturing the wide spectrum of signals detectable in a TEM, including structural, chemical, and even electronic contrast, represents a significant milestone in the realm of nanoelectronics. In situ studies hold particular promise for the development of Metal-Insulator-Metal (MIM) devices for use in next-generation computing. However, achieving successful device operation in the TEM typically necessitates meticulous sample preparation involving focused ion beam (FIB) systems. Conducting contamination introduced during the FIB thinning process and subsequent attachment of the sample onto a MEMS-based chip remains a formidable challenge. This article delineates an improved FIB-based sample preparation methodology that results in good electrical connectivity and operational functionality across various MIM devices. To exemplify the efficacy of the sample preparation technique, we demonstrate preparation of a clean cross section extracted from a Au/Pt/BaSrTiO3/SrMoO3 tunable capacitor (varactor). The FIB-prepared TEM lamella mounted on a MEMS-based chip showed current levels in the tens of picoamperes range at 0.1 V. Furthermore, the electric response and current density of the TEM lamella device closely align with macro-scale devices. These samples exhibit comparable current densities to their macro-sized counterparts thus validating the sample preparation process and confirming device connectivity. The simultaneous operation and TEM characterization of electronic devices enabled by this process enables direct correlation between device structure and function, which could prove pivotal in the development of new MIM systems.

A cryogenic tune and match circuit for magnetic resonance microscopy at 15.2T

Background and SignificanceAchievable signal to noise ratios (SNR) in magnetic resonance microscopy images are limited by acquisition times and the decreasing number of spins in smaller voxels. A common method of enhancing SNR is to cool the RF receiver coil. Significant SNR gains are realized only when the Johnson noise generated within the RF hardware is large compared to the electromagnetic noise produced by the sample. Cryogenic cooling of imaging probes is in common use in high field systems, but it is difficult to insulate a sample from the extreme temperatures involved and in practice imaging cryoprobes have been limited to surface or partial volume designs only. In order to use a solenoid in which the windings were not directly cooled and in close proximity to the sample, we designed a chamber to cool only the tune and match circuitry and show experimentally it is possible to achieve much of the theoretically available SNR gain. MethodsA microcoil circuit consisting of two tuning capacitors, one fixed capacitor, and SMB coaxial cable was designed to resonate at 650 MHz for imaging on a Bruker 15.2 T scanner. Sample noise increases with the sample diameter, so surface loops and solenoids of varying diameters were tested on the bench to determine the largest diameter coil that demonstrated significant SNR gains from cooling. A liquid N2 cryochamber was designed to cool the tune and match circuit, coaxial cable, and connectors, while leaving the RF coil in ambient air. As the cryochamber was filled with liquid N2, quality factors were measured on the bench while monitoring the coil's surface temperature. Improvements of SNR on images of ionic solutions were demonstrated via cooling the tune and match circuit in the magnet bore. ResultsAt 650 MHz, loops and solenoids < 3 mm in diameter showed significant improvements in quality factor on the bench. The resistance of the variable capacitors and the coaxial cable were measured to be 45% and 32% of room temperature values near the Larmor frequency. Images obtained with a 2 turn, 3 mm diameter loop with the matching circuit at room temperature and then cooled with liquid nitrogen demonstrated SNR improvements of a factor of 2. ConclusionsBy cooling the tune and match circuit and leaving the surface loop in ambient air, SNR was improved by a factor of 2. The results are significant because it allows for more space to insulate the sample from the extreme temperatures used in imaging cryoprobes.

A new ultra-low power wide tunable capacitance multiplier circuit in subthreshold region for biomedical applications

Implementing large capacitors in integrated circuits demands an occupation of a relatively significant large silicon area on-chip, which strictly limits the capability of the physical implementation of low-frequency integrated circuits that mostly require high capacitance values to provide large time-constants. Capacitance multipliers have been proposed to overcome this issue to realize high-value active capacitances in a small chip area. This paper proposes a new current-mode ultra-low power capacitance multiplier based on the floating capacitance Super Flipped Current Follower (SFCF) circuit which employs two AB class cascaded stages. The main novel idea behind the proposed circuit is combining the cross-coupling Quasi-Floating Gate (QFG) with the class-AB techniques and employing the Super Flipped Current Follower (SFCF) circuit, to enhance the adjustment efficiency ratio (M) factor, while also achieving a high scaling factor “K”. As a result, the proposed circuit achieves higher K value at the lower power and chip size area costs, while providing better adjustment efficiency ratio (M), which realizes a better “capacitance adjustability-power” trade-off. The proposed circuit provides other advantages such as: wide electronic tunability of scaling factor K, large Parallel Load Resistance (PLR) value, small value of Equivalent Series Resistance (ESR), relatively small chip size area, and a high ratio of adjustment efficiency (M). The total power consumption of the proposed circuit is obtained as 101 nW, using a base capacitance (Cb) of 1 pF, which leads to the realization of a maximum achievable equivalent capacitance (Ceq) of 1604 pF. In addition, the performance of the proposed tunable capacitance multiplier is examined in the realization of a wide-tunable low-pass filter structure. Furthermore, the performance robustness of the proposed circuit is investigated by the Monte-Carlo and PVT analyses in different technology corners, which justify the good performance of the proposed circuit that makes it a proper candidate to be used in ultra-low power biomedical signal processing.

Composite Right/Left-Handed Leaky-Wave Antenna with Electrical Beam Scanning Using Thin-Film Ferroelectric Capacitors

This article presents a wide-angle-scanning leaky-wave antenna (LWA) based on a composite right/left-handed (CRLH) transmission line. In contrast to traditional semiconductor elements, thin-film ferroelectric capacitors were implemented in the CRLH unit cells to enable electric beam scanning. The proposed CRLH LWA has a single-layer design without metalized vias and is compatible with PCB and thin-film technologies. To fabricate the CRLH LWA prototype, dielectric material substrates and thin-film ferroelectric capacitors were manufactured, and their characteristics were investigated. Double-sided metalized fluoroplast-4 reinforced with fiberglass with a permittivity of 2.5 was used as a substrate for CRLH LWA prototyping. A solid solution of barium strontium titanate (BaxSr1−xTiO3) with a composition of x=0.3 was used as a ferroelectric material in electrically tunable capacitors. The characteristics of the manufactured ferroelectric thin-film capacitors were measured at a frequency of 1 GHz using the resonance method. The capacitors have a tunability of about two and a quality factor of about 50. The antenna prototype consists of ten units with a total length of 1.25 wavelengths at the operating frequency of close to 2.4 GHz. The experimental results demonstrate that the main beam can be shifted within the range of −40 to 16 degrees and has a gain of up to 3.2 dB. The simple design, low cost, and excellent wide-angle scanning make the proposed CRLH LWA viable in wireless communication systems.