Direct Current Output Research Articles

Research on Underwater Constant High-Voltage DC Switching Technology for MCSEM.

The marine controlled source electromagnetic (MCSEM) transmitter can transmit high currents near the seabed to detect the electrical structure of the seafloor. The use of three-phase alternating current (AC) transmission can lead to three-phase imbalance, which results in an excessive current in one phase's power line and affects the safety of the tow cable. This paper proposes an MCSEM underwater constant high-voltage direct-current (DC) switching scheme that replaces AC transmission with DC transmission. This scheme can fundamentally avoid three-phase imbalance and the AC loss caused by inductance. After establishing a simulation model to analyze the effect of the scheme, the relevant hardware units were designed. The hardware unit mainly consists of three parts: a DC switching inverter unit, a filter unit, and a step-down rectification unit. The DC inverter unit controls six insulated gate bipolar transistor (IGBT) modules with sinusoidal pulse width modulation (SPWM) signals to convert DC to three-phase AC power; the filter unit filters out extra harmonic components; and the step-down rectification unit converts high-voltage three-phase AC to low-voltage DC. The scheme ultimately achieved an adjustable DC output of 48.3-73.4 V under a constant DC input voltage of 3000 V and effectively reduced the current on the cable. This scheme has the potential to replace the previous AC transmission, reducing the risk of tow cable burnout and enhancing the safety of MCSEM operations.

Tribo-hygro-electric generator: Harnessing mechanical energy with liquid-infused porous cellulose for multiple sensing and DC power generation

This study introduces the Tribo-Hygro-Electric Generator (THEG), a novel device that harvests ambient mechanical and water-enabled energies for highly sensitive, self-powered multi-sensing. THEG employs a simple design using liquid-infused porous cellulose (LIPC), created by absorbing functional liquids such as water into porous cellulose, and metal contacts with distinct work functions (e.g., Al and Cu) to generate triboelectric charges through friction. It operates via a three-step process: generating triboelectric charges through sliding motion, establishing an internal electric field across Al/LIPC/Cu interfaces for charge separation, and directing charges to create unidirectional output electron transfer, producing direct current (DC) outputs. The principle behind THEG emphasizes the critical role of the single Schottky contact at the Al/LIPC interface in separating and directing charge transfer, as well as the conductive path formed by the hydrogen-bonded network of water molecules and cellulose’s functional groups. THEG can harvest DC power with a current density of up to 3.4 A/m² and 0.5 V, which can be increased to 2 V with four cells in series. THEG demonstrates impressive multiple-sensing capabilities, with robust linear relationships (correlation coefficients > 0.99) between output current density and stimuli such as pressure, velocity, water absorption, and ion concentration. Demonstrating practical utility, the generated energy powers devices like a commercial calculator. This technology advances mechanical energy harvesting and multiple sensing, reducing dependence on external power and enabling transformative IoT applications.

Coupling of Tribovoltaic Effect and Tribo-Electrostatic Effect at Dynamic Semiconductor Heterojunction Interfaces

Tribovoltaic effect at the dynamic semiconductor interface is of great fundamental and practical importance for developing a variety of functional devices; yet, it can be coupled with a series of different physical effects, such as the contact-electrification induced electrostatic effect and mechanical wearing effect, and the coupling mechanisms are still remained to be elucidated. Herein, we investigated the coupling between tribovoltaic and tibo-electrostatic effects at the dynamic heterojunctions of two wide-bandgap semiconductors: zinc oxide (ZnO) and gallium nitride (GaN). It is found that, in the contact-separation mode, the direct-current outputs from tribovoltaic effect can be clearly distinguished from the alternating-current outputs from tribo-electrostatic effect. Then, humidity, external load resistance and pressure force are found to reveal the coupling characteristics of these two effects, that tribovoltaic outputs are less affected by humidity, show smaller matched impedance and are more sensitive to high pressure force, diverging from the tribo-electrostatic outputs. Lastly, we demonstrate that the mechanical wearing effect can be inhibited in contact-separation mode, achieving long-term stability over 50,000 cycles. Therefore, this work provides insights to the mechanism of tribovoltaic effects and practical guidance for high-performances tribovoltaic devices.

High performance DC-TENG based on coupling of mismatched number of triboelectric units and electrodes with mechanical switches for metal surface anti-corrosion

Triboelectric nanogenerator (TENG) have proven to be a promising technology for harvesting dispersed mechanical energy. However, traditional TENGs based on triboelectrification and electrostatic induction generate electricity in alternating current (AC) mode, which needs to be converted into direct current (DC) for most applications. Here, we propose a DC-TENG based on the coupling of mismatched number of triboelectric units and electrodes with a mechanical switch design. This design not only simplifies the structure compared with previous multi-phase TENG and minimizes power loss, but enables a stable DC generation without post-management, which can be used directly to metal surface anti-corrosion. The experimental results show that the output current of this TENG with the mismatched number of triboelectric units (T) and electrodes (E) in 2T3E, 4T5E and 6T7E increases from 16.96 μA to 32.46 μA, achieving maximum power density of 33.20 mW with an external resistance of 80 MΩ. This enhancement in performance illustrates the effectiveness of the proposed design for harvesting and converting energy efficiently. Furthermore, the application of the mismatched MTE-TENG as a power source for metal surface anti-corrosion is explored. Through immersion experiments and electrochemical tests, the corrosion current decreases from 29.59 μA to 3.15 μA compared with bare carbon steel, which significant decreases in both anodic and cathodic branch currents, indicating the achievement of the anti-corrosion effect. This work provides a new way to achieve high DC output for metal surface anti-corrosion and realizes a green electrochemical anticorrosion process.

A metasurface antenna with beam steering capabilities for radio frequency energy harvesting

Limited control over parameters within the realm of design complexity, it is noted that there are incomplete unit cells displaying slightly lower transmittance in transmissive metasurface antennas. However, traditional methods require time-consuming iterative processes to select unit cells with multiple variables. Therefore, a novel approach is proposed for designing metasurface superstrates on patch antennas operating at 12.5 GHz, focusing on achieving beam steering capabilities and Radio Frequency (RF) energy harvesting functionality. It utilizes a Skeleton-based Attentions Neural Network (SANN) to aid in the complex metasurface unit cell design, enhancing the antenna's flexibility and potential applications. This network is trained to generate patterns for the metasurface unit cell, facilitating accurate and efficient design. The key feature of this antenna is beam steering in multiple directions. Steering is achieved by rotating the metasurface plane in an anti-clockwise direction. Experimental results show that by rotating the metasurface plane at different angles, the beam is directed towards specific directions, such as 10°, 15°, 18°, 21°, and 23°. A load resistance of 8kᾨ and a full wave rectifier with a Positive-Intrinsic-Negative (PIN) diode are utilized to obtain a Direct Current (DC) output voltage of 1.1 V in the proposed rectifier. Copper material is used for the metasurface plane, and the antenna is measured using RT duriod.

Performance-enhanced tribovoltaic nanogenerator by regulating carrier transportation with an asymmetric heterostructure

The tribovoltaic nanogenerator (TVNG) is emerging as a promising circuit-integrative energy harvester, with notable advantages like direct current output and large current density. Nevertheless, the research on optimizing charge excitation and carrier transportation remains deficient. In this work, we report an alternative approach for practically promoting the output performance of silicon (Si)-based TVNG. A well-designed asymmetric heterostructure is achieved by inserting an appropriate interlayer between the friction layer and the bottom electrode. Carrier extraction efficiency has been promoted effectively, while carrier recombination has been restrained owing to the built-in electric field excited by p-Si/ZnO heterojunction. The coupling mechanism of the built-in electric field and the interfacial electric field has been revealed explicitly with a comprehensive theoretical model, which is based on the capacitance feature of the PN junction. The designed multilayer TVNG (MTVNG) has shown 20 times higher output compared to normal Si-based TVNGs. Apart from presenting fundamental insights into the tribovoltaic effect, we have developed a dual-mode analysis method for vibration monitoring. This work expands the path to improve TVNG output through multi-electric field coupling and provides new inspiration for miniaturized vibration sensors in real-time deployments.

Research on Control Strategy of PMSG-PWM Power Generation System with Tidal Energy

Aiming at the characteristics of machine-side output instability and the wide-range variation in the tidal energy PMSG-PWM power generation system, we propose a control scheme with a high anti-interference capability applied to the PWM rectifier. The outer voltage loop adopts sliding mode control (SMC) with the variable exponential convergence law based on expanded state observer (ESO). By compensating the perturbation observation value into the sliding mode controller in advance, it improves the robustness and response speed of the system and suppresses the direct current (DC)-side voltage jitter phenomenon. The current inner loop combines model prediction (MP) with direct power control (DPC). By introducing time-delay compensation, it improves the control accuracy, reduces the machine-side harmonic content, and enables the system to maintain unit power factor operation despite external disturbances. Simulation and experiment results show that, under the wide range of PMSG output, the PMSG-PWM power generation system adopting the “ESO_SMC+MDPDC” scheme has a fast dynamic regulation of DC output voltage, obvious vibration suppression effect, low harmonic content of the current on the PMSG side, and fast current tracking speed, which verify the feasibility of applying this system to the field of tidal energy generation.

Charge Accumulation Effect Enabled by a Bioinspired Self‐lubricating Triboelectric Nanogenerator for Both High Average Power Density and Long Durability

AbstractRecently through the synergetic utilization of triboelectrification, electrostatic induction, and electrostatic discharge, a novel dual‐functional triboelectric nanogenerator (DF‐TENG) has been developed, which can not only generate a motion‐responsible alternating current/ direct current output but also provide a higher performance compared to traditional TENGs. However, further improvements in performance and lifespan are crucial and remain challenging for the future large‐scale application of this new‐type TENG. Herein, a novel bioinspired self‐lubricating prototype is presented (BS‐TENG), which employs a porous polyurethane (PU) matrix impregnated with a low‐viscosity dielectric lubricant. In response to external mechanical stimuli, the BS‐TENG can “secrete” pre‐stored lubricant to partially fill micro‐gaps between tribo‐layers, thus forming self‐lubrication. This self‐lubricating mechanism not only elevates the electrostatic discharge threshold between tribo‐layers to maximize charge accumulation, thereby facilitating efficient energy release through electrostatic discharge for enhanced power output, but also significantly reduces material abrasion and realizes superior output durability. Benefiting from this effect, the BS‐TENG delivers an average power density of up to 4.6 W m−2, with extraordinary stability to retain 99% of its initial output even after over 60 000 cycles. This work provides a straightforward and effective strategy for realizing high‐performance and long‐stability TENGs, paving the way for their practical applications.

Power converter for battery charger of electric vehicle with controllable charging current

Research on electric vehicle chargers primarily focuses on improving charging technology to enhance the convenience, quality, efficiency, and affordability of charging electric vehicles. This paper discusses a different AC-DC power converter topology proposed as a potential candidate for electric vehicle battery charger. Using the proposed converter circuit, the charging process of electric vehicle battery can be simply adjusted to meet the battery requirement, and even for increasing the charging speed while avoiding overcharging of battery. During the charging process, if the voltage of battery approaches to the targeted battery voltage level, the charging current can be reduced gradually to zero. Hence it will prevent the battery from overcharging condition. Moreover, the ability of working at high power factor operation, low distortion of alternating current (AC) input current, and low direct current (DC) output current ripple are other features of the proposed charger circuits. Some test results of the proposed power converter were presented. The test results revealed potential features of the converter for battery charger of electric vehicle with power factor 0.9996, total harmonic distortion (THD) of AC current 2.73%, and low charging current ripple, i.e. 3.91%. Therefore, it minimizes the negative effects caused by ripples of charging current especially for lithium-ion batteries widely used in electric vehicles.

A generalized model for tribovoltaic nanogenerator

Converting mechanical energy into direct-current electric power based on the tribovoltaic effect is a typical characteristic of tribovoltaic nanogenerators (TVNGs). Although this newly discovered physics effect has been devoted to numerous research studies recently, a generalized theoretical model is still missing, thus unable to comprehensively elaborate the working principles of TVNG. Unlike previous qualitative explanations restricted to the conventional diffusion-drift theory, a new theoretical model is proposed according to classical semiconductor physics. Using the model, the governing equation of a TVNG is derived for the first time, which provides possibilities for revealing the variations of basic physical variables whether within the device or in an external circuit. The direct-current output is suggested to be the coupling of the tribovoltaic effect and contact electrification; in detail, it directly results from the movement and realignment of quasi-Fermi levels for excess carriers that are contiguous to the junction/contacting interface under non-equilibrium conditions. Moreover, an equivalent circuit model is established, equivalent to a constant current source parallel to a p–n junction diode according to the lumped parameter circuit theory. Notably, a new term, mechano-induced electric field EM, is defined and introduced to describe the impact of triboelectric charges at interfaces. Furthermore, using the COMSOL Multiphysics software, a dynamic simulation model for TVNGs is proposed, allowing the simulation and calculation of various TVNGs with different geometric constructions and charge distributions.

Bidirectional rotating direct-current triboelectric nanogenerator with self-adaptive mechanical switching for harvesting reciprocating motion

Abstract Amid the growing interest in triboelectric nanogenerators (TENGs) as novel energy-harvesting devices, several studies have focused on direct current (DC) TENGs to generate a stable DC output for operating electronic devices. However, owing to the working mechanisms of conventional DC TENGs, generating a stable DC output from reciprocating motion remains a challenge. Accordingly, we propose a bidirectional rotating DC TENG (BiR-TENG), which can generate DC outputs, regardless of the direction of rotation, from reciprocating motions. The distinct design of the BiR-TENG enables the mechanical rectification of the alternating current output into a rotational-direction-dependent DC output. Furthermore, it allows the conversion of the rotational-direction-dependent DC output into a unidirectional DC output by adapting the configurations depending on the rotational direction. Owing to these tailored design strategies and subsequent optimizations, the BiR-TENG could generate an effective unidirectional DC output. Applications of the BiR-TENG for the reciprocating motions of swinging doors and waves were demonstrated by harnessing this output. This study demonstrates the potential of the BiR-TENG design strategy as an effective and versatile solution for energy harvesting from reciprocating motions, highlighting the suitability of DC outputs as an energy source for electronic devices.

Service life estimation of electric vehicle lithium-ion battery pack using arrhenius mathematical model

Durability is a desired characteristic for all battery packs in Electric Vehicles. In this study, the service life of the EV battery pack under real-world operating conditions is projected using an Arrhenius mathematical simulation model. The model comprises a 39.2 kWh EV Lithium-Ion battery pack integrated with a three-phase inverter to convert the battery pack’s Direct Current output to Alternating Current. In addition, the Alternating Current output is coupled to a 100 kW permanent magnet synchronous motor, which is regarded as the load. A field-oriented controller provides pulse width-modulated output signals that are supplied back to the inverter to generate the correct driving current. Variable conditions of charge rate (C-rate: 1.25C − 4C), discharge rate (C-rate: 0.5C − 4C), temperature (25°C–60°C), and depth of discharge (30%–90%) are evaluated to determine the battery pack’s service life. Under a 4C charge rate/0.5C discharge rate and 50% depth of discharge, the modeling results indicate the battery pack has a service life of approximately 6,000 h at low temperatures (25°C) and roughly 3,000 h at high temperatures (60°C). The model has been validated by comparing the results with experimental data from the literature.

Tribovoltaic performance of the Schottky contact between metal and PZT ceramic

The sliding contact between a metal or semiconductor with another semiconductor can lead to a new charge generation mechanism known as the tribovoltaic effect. This effect has several advantage over the more common triboelectric effect, such as a higher rate of charge transfer and the ability to produce a direct current (DC) output directly via the junction interface. During operation, the junction interface produces a built-in electric field. In this study, we investigate the tribovoltaic effect on sliding between copper and unpoled lead zirconate titanate (PZT) ceramic. It was found that the contact between the metal and semiconducting oxide ceramic leads to the Schottky junction effect, which can effectively drive frictionally excited charges to an external load. By increasing the applied stress to PZT, we observed different current-voltage characteristic curves. The proposed electronic band behavior determines the electrical output direction in the tribovoltaic nanogenerator (TVNG). This direction depends on the built-in electric fields formed at the junction. The performance of the TVNG was tested in both series and parallel connections, observing clearly improved electrical outputs for both. The proposed TVNG can efficiently power small electronic devices, such as LEDs, and charge capacitors in a short period of time. This work expands the understanding of unconventional transport mechanisms through the Schottky contact of PZT and metal, and provides fundamental knowledge for the future development of tribovoltaic devices.

Droplet-Based Direct-Current Electricity Generation Induced by Dynamic Electric Double Layers.

Harvesting energy from water droplets has received tremendous attention due to the pursuit of sustainable and green energy resources. The droplet-based electricity generator (DEG) provides an admirable strategy to harvest energy from droplets into electricity. However, most of the DEGs merely generate electricity of alternating current (AC) output rather than direct current (DC) without the utilization of rectifiers, impeding its practical applications in energy storage and power supply. Here, a direct current droplet-based electricity generator (DC-DEG) is developed by the simple configuration of the electrodes. The DC output originates from the dynamical electric double layer (EDL) formed at two electrodes and droplet interfaces where the charging/discharging process of EDL capacitance occurs. Several experiments are exhibited to demonstrate the rationality of the proposed principle. The influence of some factors on the output is investigated for further insight into the DC-DEG device. This work provides a novel strategy to harvest energy from water droplets directly into DC electricity and may expand the application of DEGs in powering electronic devices without the help of rectifiers.

Ionic Rectification by Dynamic Regulation of the Electric Double Layer at the Hydrogel Interface.

Hydrogels play a pivotal role in the realm of iontronics, contributing to the realization of futuristic human-machine interactions. The electric double layer (EDL) between the hydrogel and electrode provides an essential ionic-electronic coupling interface. While prior investigations primarily delved into elucidating the formation mechanism of the EDL, our study shifts the focus to showcasing the current generation through the mechanical modulation of the EDL at the hydrogel-metal interfaces. The dynamic EDL was constructed by the mechano-driven contact-separation process between the polyacrylamide (PAAm) hydrogel and Au. Influencing factors on the dynamic regulation of the EDL such as ion concentration, types of salt, contact-separation frequency, and deformation degree were investigated. Dehydration usually limits the practical applications of hydrogels, and it is a long-standing and difficult problem. However, it seemed to be able to slow the EDL formation process here, resulting in a sustained continuous direct current signal output. Such hydrogel iontronics could rectify the displacement electronic current of a triboelectric nanogenerator by the ionic current. The directional migration of ions could be further enhanced by using charge-collecting metals with different work functions, for example, Au and Al. It offers a paradigm to enable ionic rectification that could be seamlessly incorporated into electronic systems, ushering in a new era for efficient energy harvesting and biomimetic nervous systems.

Boosted outputs and robustness of polymeric tribovoltaic nanogenerator through secondary doping

The semiconductor-based tribovoltaic nanogenerator (TVNG) garners distinctive characteristics of direct current output at low internal impedance, rendering it great potentials for self-powered electronics. We present a polymeric TVNG for achieving enhanced electrical outputs and robustness through secondary doping strategy. By utilizing the dimethyl sulfoxide (DMSO) as a dopant, the transport properties of semiconducting poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) can be modulated. We then demonstrate that the tribovoltaic outputs can be significantly enhanced due to the improved conductivity of the PEDOT:PSS and the enlarged Schottky barrier at the dynamic metal–semiconductor interfaces. The quantity of the transferred charge per motion cycle can reach 150.48 mC m−2 in contact-separation mode and 225.73 mC m−2 in sliding mode. Meantime, the dopant improves the flexibility of the PEDOT:PSS and hence the mechanical robustness of TVNG, allowing stable outputs for ∼ 100,000 contact-separation operations cycles or ∼ 36,000 bending cycles. Furthermore, the device also demonstrates exceptional humidity resistance, but confirms a coupling of tribovoltaic effect and electrochemical effect in high-humidity conditions (relative humidity over 90%). Therefore, our findings provide insightful strategies for future optimization of practical tribovoltaic devices.

Electrostatic generator enhancements for powering IoT nodes via efficient energy management

Electrostatic generators show great potential for powering widely distributed electronic devices in Internet of Things (IoT) applications. However, a critical issue limiting such generators is their high impedance mismatch when coupled to electronics, which results in very low energy utilization efficiency. Here, we present a high-performance energy management unit (EMU) based on a spark-switch tube and a buck converter with an RF inductor. By optimizing the elements and parameters of the EMU, a maximum direct current output power of 79.2 mW m-2 rps-1 was reached for a rotary electret generator with the EMU, achieving 1.2 times greater power output than without the EMU. Furthermore, the maximum power of the contact-separated triboelectric nanogenerator with an EMU is 1.5 times that without the EMU. This excellent performance is attributed to the various optimizations, including utilizing an ultralow-loss spark-switch tube with a proper breakdown voltage, adding a matched input capacitor to enhance available charge, and incorporating an RF inductor to facilitate the high-speed energy transfer process. Based on this extremely efficient EMU, a compact self-powered wireless temperature sensor node was demonstrated to acquire and transmit data every 3.5 s under a slight wind speed of 0.5 m/s. This work greatly promotes the utilization of electrostatic nanogenerators in practical applications, particularly in IoT nodes.

Synergistic Coupling of Tribovoltaic and Moisture‐Enabled Electricity Generation in Layered‐Double Hydroxides

AbstractUbiquitous energy harvesting technologies require new types of renewable, sustainable, and clean energy to solve the problems of fossil fuels. Although various nanogenerators have been developed over the last decade, low current density, requirements for complicated management circuits, generation of direct current (DC) outputs, and significant performance degradation under humid atmospheres have been problems limiting practical applications. This paper reports that the tribovoltaic and moisture‐enabled electricity generation effects can be achieved in a layered double hydroxide (LDH) by applying a metal brushing mode. The ZnAl‐LDH shows enhanced tribovoltaic nanogenerator (TVNG) performance even in a high‐humidity environment coupled with the moisture‐enabled electricity generated by the concentration gradient of a water molecule through the interlamellar structures of the LDHs. The spontaneous dissociation of water in the interior of LDHs removes the hole generated by the tribovoltaic effect, allowing high efficiency of an output voltage of 693.38 mV and current density of 65.48 mA m−2 even under low‐applied force (≈3.5 mN) at relative humidity 80%. The proposed TVNG provides a proof of concept for an all‐in‐one device consisting of a generator and capacitor because the LDH reveals a spontaneous charging performance similar to that of a capacitor.

Asymmetrical Schottky Junction Built by Metal/Conducting Polymer Targeting Efficient Flexible Direct Current Tribovoltaic Generator

Direct current (DC) from mechanical energy built on the tribovoltaic effect is promising for the development of self‐powered flexible electronics. A semiconductor triboelectric generator is one of the optimized solutions for DC output. However, it remains underutilized because of its low output power and insufficient insight into the fundamental principles of charge generation and transport at dynamic interfaces. Herein, a flexible fabric‐based DC generator that relies on a metal–semiconducting polymer interface constructed by an asymmetric Schottky junction between a poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS)‐coated fabric and an aluminum (Al) foil is reported. The dependence of the electrical output performance of the device on the doping carrier concentration using different types of PEDOT:PSS to modulate the Schottky barrier height, validating both the work function and conductivity of the triboelectric material, which plays a fundamental role in DC generation, is explored. A large work function difference is required to create a high built‐in electric field for efficient separation of electron–hole pairs. Decent conductivity also fulfills an integral role in the innate carrier‐transport capability. Accordingly, an open‐circuit voltage (Voc) of 800 mV, a short‐circuit current (Isc) of 80 μA, and a power density of 6.7 mW cm−2 are yielded simultaneously.

Aperture Sharing Metasurface-Based Wide-Beam Antenna for Energy Harvesting

Since the available ambient power level is usually quite low for radio frequency energy harvesting, it is very desirable for an antenna to have both a high gain and a wide beamwidth. Usually, they cannot be achieved simultaneously. In order to overcome this limitation, a multi-port antenna using a nonuniform metasurface (MTS) is presented. In this MTS-based antenna, three modes with complementary radiation patterns are excited through one middle and two side aperture-coupled feeding ports. The first mode is the fundamental TM10 mode with in-phase current distributions on the MTS. It has a broadside directional radiation pattern with a high gain. The second and third modes are symmetrical to each other at a high mode. They have opposite current distributions on two sides of the MTS. These two modes have a directional radiation pattern with a tilted angle. These three modes share the same aperture but are excited by three different feeds. Each feed is connected to a rectifier. By combining direct current (DC) output to a single load, an antenna with a wide beam and a high gain can be effectively achieved, although each mode has the usual limitation of gain and beamwidth. The key advantage of this proposed rectenna is that the unit cells on the MTS layer can be reused to excite different MTS modes with different radiation patterns simultaneously. Thus, a wide beamwidth can be achieved. Three realized beams are oriented at −35°, 0°, and + 35° respectively. By combining the DC output from the three modes, the proposed rectenna has effectively achieved a beamwidth of 114° with a gain ranging from 8 to 9.8 dBi. The RF-to-DC conversion efficiency of the rectifiers is 3%-67% at 2.45 GHz when the input power ranges from −35 to 0 dBm. The proposed MTS antenna with an overall size of λ0 × λ0 × 0.03 λ0 can achieve 12% fractional bandwidth.