Radio Frequency Module Research Articles

Current status of ECE system on EAST tokamak

The electron cyclotron emission (ECE) diagnostic on the experimental advanced superconducting tokamak (EAST) has had a major upgrade since 2020, when EAST heating system also went through a significant upgrade, including one NBI system changed from counter-current to co-current (moving from port F to port D), and the antenna and the installation port of LHW and ICRF system have also been changed. The quasi-optical (QO) antenna of P port ECE system has been redesigned, the main purpose of which is to add one oblique ECE view. The angle with respect to perpendicular to the magnetic field is about 10°, which will facillitate measurement of the electron velocity distribution altered by LHW system. The ellipsoidal mirror has also been moved close to the plasma, about 70 cm away from the plasma center, and the poloidal beam waist radius in the plasma has been optimised to be less than 3 cm. The CECE system has also been moved from port G to port C. The frequency coverage of the CECE system has been upgraded to 104-132 GHz by adding one radio frequency (RF) module. Also in the intermediate frequency (IF) module, 8 narrow-band filters have been added to improve the spacial coverage of the system. On port F, a new superheterodyne radiometer with narrow-band filters in IF module has been installed. It consists of eight channels, the radial coverage is about 8 cm, the main purpose of this new system is to study the fine structure of magnetic island.

Reaching the Frequency Resolution Limit in a Single-Shot Spectrum of an Ultra-Short Signal Pulse Using an Analog Optical Auto-Correlation Technique

This work demonstrated a high-resolution spectrum obtained from a single ultra-short high-frequency signal pulse using a new analog optical auto-correlation method that revolutionizes the signal detection and measurement technique. It provides unprecedented capability to reach the fundamental limit in Physics. This technique allows us to increase the observation/measurement time by converting a Radio Frequency (RF) signal in the optical domain and keeping the “live-signal” in a fiber-optic-recirculation-loop circuit over an extended time that could be a million times longer than the pulse width. The dispersion delay of the two RF modulation sidebands is used to perform an analog time correlation. It effectively stretches time by million times. As a result, it provides a frequency-space “snapshot” of ultra-short events without the need for a high-speed analog-to-digital converter (ADC). A single 30 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ns</i> -short two-tone pulse separated by 25 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MHz</i> was resolved in a 50 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GHz</i> wideband real-time frequency spectrum. This technique allowed us to push the physical limit in the spectral resolution of an ultra-short signal and enable a new technology to manipulate, process, and analyze ultra-short electromagnetic signals and transient events. It also provokes a fundamental question: Is the uncertainty principle limiting the frequency determination for a wave in a continuum state?

Symbol State Transition Entropy: A Novel Feature of Interpulse Radio Frequency Modulation Signal

In radar electronic warfare (EW) reconnaissance, radio frequency (RF) is an important parameter for describing the received pulse, and it is usually used in sorting and identifying radar signals. In order to achieve different detection purposes, different modulations are used in intra-pulse and interpulse radar signals. It is an important frequency modulation mode in radar signals for interpulse frequency modulation, which describes the characteristics of dynamic changes of radar pulse signals. However, it is difficult to describe these characteristics effectively by only using Pulse Description Word(PDW). In this letter, a novel feature, based on symbolization and entropy, is proposed to characterize interpulse frequency modulation characteristics of radar signals. Simulation results show that the proposed feature not only have an excellent performance of describing interpulse RF modulation radar signals, but is also insensitive to the environment with a certain rate of pulses missing and spurious pulses. Besides, in terms of time complexity, it also has a satisfactory performance.

A study to determine electromagnetic interference‐shielding effectiveness on bio‐based polyurethane foam reinforced with PVDF/MgO/Ni for emerging applications

AbstractThe main objective of this study is to prepare nanoparticles‐induced bio‐based polyurethane foam to shield electromagnetic interference (EMI) radiation in the 8–12 GHz frequency range and compare the experimental result with optimization and simulation. Polyvinylidene fluoride (PVDF), magnesium oxide (MgO), and Nickel (Ni) nanoparticles were induced into bio‐based PU (polyurethane) foam through absorption and hydrothermal reduction technique, which includes mechanical stirring, compressing, heating and evaporating. The design of experiment (DOE) methodology was used to find nanoparticle weight percentage (wt%). EMI shielding effectiveness of the bio‐based PU foam composite was measured using Vector Network Analyzer (N5230A PNA‐L). The weight percentages of the optimized sample were predicted using the response surface methodology (RSM), in which the central composite design (CCD) employed the weight percentages of the three nanoparticles as input and the results of the electromagnetic interference shielding effectiveness (EMI SE) experiment as the response output. The result from CCD showed that 3 wt% of PVDF, 10 wt% of MgO, and 1 wt% of Ni gave a maximum EMI SE of 27.78 dB. Then a confirmation sample was created for the same, and EMI SE was estimated empirically. The results obtained for the confirmation sample are 27.56 dB. Then, a scanning electron microscope image was taken for the confirmation sample to analyze nanoparticle‐induced bio‐based PU foam's structural properties. The SEM image with dxf format is imported into the radio frequency (RF) module to calculate the EMI SE through COMSOL Multiphysics. The simulated EMI SE for the confirmation sample was 25.1 dB.

Nitrogen doped ZrO2 thin films: synthesis and characterization

To obtain ZrO2 and ZrO2+N2 thin films was used magnetron sputtering in radio frequency mode in a 10-6 mbar high vacuum deposition chamber. Silicon and carbon substrates measuring 12x15mm were used for deposition. The used magnetron system was composed of a single water-cooled cathode, provided with one circular targets of ZrO2 (2 mm thick and 50 mm in diameter) of high purity (99.95%). TDS Analysis of the films was performed. The desorbed species were observed with a QMG 220 Mass spectrometer provided with a W filament. It can be observed that in the case of the ZnO2 film, nitrogen desorption registers two maxima with signal intensity of 9.7x10-12 and 9.0x10-12, reached after 2000s and 4900s respectively. In the case of ZrO2+N2 film, nitrogen desorption shows a pronounced maximum with a signal intensity of 2.4x10-11 reached after 6000s. . The topology the ZrO2 and ZrO2+N2 samples deposited on Si substrates have been investigated by scanning electron microscopy (SEM) using a FEI Inspect S scanning electron microscope ( Hillsboro, Oregon, OR, USA) in high-vacuum modes. For the ZrO2 deposition, the surface appears to have grain-like topology, with a mean dimension of around 150 nm. These structures do not appear for the ZrO2+N2 deposition. Instead, for the ZrO2+N2 sample, small blisters (between 300 nm and 1.000nm) have formed on the surface, as a consequence of injecting N2 during the deposition. Cross-section measurements were also performed to establish the layer thickness. The ZrO2 sample has a measured thickness of 1950nm, while the introduction of N2 gas for the ZrO2+N2 sample had a poisoning effect on the magnetron target that led to a decrease (5 times) in deposition rate, giving this sample a final thickness of 365nm (compared to 1950nm) for the same deposition The crystalline structure was investigated using X-Ray Diffraction (XRD) method. The experimental set-up was composed of a diffractometer equipped with a Cu-Kα X-ray sourse, with a specific wavelength of 0.154nm, in a Bragg-Bretano type geometry. In this way, a crystalline phase corresponding to ZrO2 with a group symmetry Fm-3m (225)-face centered cubic was identified. At the same time, it is observed that the films deposited in the reactive atmosphere show a pronounced amorphization, this most likely being due to the retention of nitrogen which leads to the modification of the network parameters.

Design of a planar filtering power divider with wide-stopband suppression

ABSTRACT According to the development demand for radio frequency module function integration, a filtering power divider with wideband external suppression and high isolation is designed based on the traditional Wilkinson power divider. The working mechanism of the device is analyzed by using the odd-even mode method. Utilizing the branch loading on the coupled-line and the addition of a step impedance open-circuit stub, we can realize the filtering function, widen the passband bandwidth, and improve the performance of stopband rejection. Through the bending of microstrip line between the input and output parts, it is conducive to the physical access of isolation resistance, and the isolation performance between output ports is improved. The research results show that the central working frequency of the filtering power divider is 2.85 GHz (f 0). The 3 dB bandwidth width is 1.51 GHz, and the relative bandwidth is 52.9%. The out-of-band suppression is lower than −20 dB in the range of 3.96 to 11.1 GHz (3.89f 0), and the isolation between output ports is lower than −24.4 dB in the ultra-wideband range of DC to 12 GHz. The device has excellent application prospects in radio frequency communication systems, such as amplifiers and antenna arrays.

Thermal property evaluation of a 2.5D integration method with device level microchannel direct cooling for a high-power GaN HEMT device

Gallium nitride high electron mobility transistor (GaN HEMT) devices have become critical components in the manufacturing of high-performance radio frequency (RF) or power electronic modules due to their superior characteristics, such as high electron saturation speeds and high power densities. However, the high heat characteristics of GaN HEMTs make device level cooling a critical problem to solve since performance degradation or even failure may occur under high temperatures. In this paper, we proposed a 2.5D integration method with device-level microchannel direct cooling for a high-power GaN HEMT device. To demonstrate this technological concept, a multigate GaN HEMT device featuring a gate length/width/source drain spacing of 0.5 μm/300 μm/6 μm that underwent in-house backside thinning and metallization was used as the test vehicle. A high-resistivity silicon (HR Si) interposer embedded with four-layer microchannels was designed, having widths/pitches of 30 μm/30 μm at the top microchannel. The high-power GaN HEMT device was soldered on a Si interposer embedded with open microchannels for heat dissipation. A pair of GSG Pad chips was soldered simultaneously to display the capacity for the heterogeneous integration of other chip types. Thermal property evaluation was conducted with experiments and simulations. The test results showed that the maximum surface temperature of the GaN HEMT device decreased to 93.8 °C when it experienced a heat dissipation density of 32 kW/cm2 in the gate finger area and an average heat dissipation density of 5 kW/cm2 was found in the active area with the DI water coolant at a flow rate of 3 mL/min. To our knowledge, among recently reported works, this finding was the best cooling capacity of heterogeneously integrated microchannels for GaN HEMT devices. In addition, this technology was scalable regarding the numbers of gate fingers or GaN HEMT devices.

Demonstration of Intelligent Hybrid FSO/RF System Based on Enhanced GRU Prediction and Real-World Meteorological Dataset

Hybrid free space optical (FSO)/radio frequency (RF) system has emerged as a high-data-rate solution for the last mile access network. In this paper, we establish a hybrid FSO/RF testbed including an intensity modulation/direct detection (IM/DD) FSO subsystem with space diversity and a high-order quadrature amplitude modulation (QAM) RF subsystem with polarization diversity, respectively. Based on the testbed, we propose and experimentally validate an intelligent transmission system where the link selection and switching technology is implemented. In particular, we propose a gated recurrent unit (GRU) neural network enhanced by time attention mechanism for the hybrid system. The experimental results demonstrate that the proposed system can achieve the prediction of FSO channel fading with a high precision where absolute percentage error (APE) values lower than 3% account for up to 90% of the prediction results. The implemented intelligent hybrid system can significantly reduce the link switching frequency and link interruption duration. Then the BER is further verified on the testbed, and results show that the intelligent hybrid system can improve the BER from the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> to the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> during the time periods when link switching occurs.

A Discrete Multi-Objective Artificial Bee Colony Algorithm for a Real-World Electronic Device Testing Machine Allocation Problem

With the continuous development of science and technology, electronic devices have begun to enter all aspects of human life, becoming increasingly closely related to human life. Users have higher quality requirements for electronic devices. Electronic device testing has gradually become an irreplaceable engineering process in modern manufacturing enterprises to guarantee the quality of products while preventing inferior products from entering the market. Considering the large output of electronic devices, improving the testing efficiency while reducing the testing cost has become an urgent problem to be solved. This study investigates the electronic device testing machine allocation problem (EDTMAP), aiming to improve the production of electronic devices and reduce the scheduling distance among testing machines through reasonable machine allocation. First, a mathematical model was formulated for the EDTMAP to maximize both production and the scheduling distance among testing machines. Second, we developed a discrete multi-objective artificial bee colony (DMOABC) algorithm to solve EDTMAP. A crossover operator and local search operator were designed to improve the exploration and exploitation of the algorithm, respectively. Numerical experiments were conducted to evaluate the performance of the proposed algorithm. The experimental results demonstrate the superiority of the proposed algorithm compared with the non-dominated sorting genetic algorithm II (NSGA-II) and strength Pareto evolutionary algorithm 2 (SPEA2). Finally, the mathematical model and DMOABC algorithm were applied to a real-world factory that tests radio-frequency modules. The results verify that our method can significantly improve production and reduce the scheduling distance among testing machines.

Athermal Microwave Photonic Sensor Based on Single Microring Resonance Assisted by Machine Learning

We propose a machine learning (ML) assisted athermal microwave photonic (MWP) sensing scheme with high resolution based on a single microring resonance. The immunity of temperature interference of the high-resolution sensing is achieved by employing MWP sideband processing based interrogation, and supervised machine learning based on support vector regression (SVR) and neural tangent kernel (NTK) that are effective on small datasets. The MWP sideband processing transforms the variation of the target measurand into the shift of an ultra-deep notch in the radio frequency (RF) spectrum relieving the fabrication requirements on the microresonators, while ML accurately predicts the measurand by using the modulator bias voltage or RF passband transmission together with the RF notch position. The proposed sensor is demonstrated for relative humidity (RH) measurements using a silicon-on-insulator microring coated with polymethyl methacrylate. About 50 dB high RF rejection ratio is achieved over the sensing process, indicating a high sensing resolution. Despite the small experimental datasets, the established SVR and NTK models consistently exhibit lower mean absolute errors (MAEs) than the linear regression model in the RH prediction in the presence of temperature drifts. The NTK models achieve the lowest MAEs of 1.01% RH and 1.03% RH when the RF passband transmission and modulator bias are selected as the model input, respectively. The equivalent performances of the RF passband transmission and modulator bias voltage further demonstrate the feasibility of athermal sensing based solely on the MWP interrogation results of a single microring resonance, which simplifies the design and reduces the complexity.

Optical-Frequency-Comb Generation Based on Single-Tone Modulation and Four-Wave Mixing Effect in One Single Semiconductor Optical Amplifier

We propose a novel optical-frequency-comb (OFC) generation scheme based on single-tone modulation and the four-wave mixing (FWM) effect in one single semiconductor optical amplifier (SOA) modulated by a radio frequency (RF) current. A comprehensive broad-band dynamic model, which considers single-tone modulation and the FWM effect, is presented. The simulated results show that, although only one single continuous-wave light is input into the SOA, an OFC with a large number of frequency components can be achieved as a result of single-tone modulation and the FWM effect in the SOA. The number of comb lines and the spectral bandwidth of the OFC increase by raising the amplitude of the RF modulation current. Increasing the input light power can increase the average optical power of the OFC. The frequency interval is tunable within a certain range by tuning the frequency of the RF modulation current injected into the SOA.

Monitoring system of photovoltaic panels using 433 MHz radio frequency module

In this article, we presented an innovative study that allows direct monitoring of the main parameters of photovoltaic panels. Our study focuses on the skills of radio frequency modules to send the main parameters of photovoltaic cells. In this paper, we used an Esp32 microcontroller in the radio frequency (RF) transmitter block and an Arduino Uno board in the receiver block, in addition, to measure current, we used a current sensor, and to measure voltage, we implemented a voltage divider. After that, we calculated the power and the energy. Note that the various measured and calculated values are stored and used via the ThingSpeak platform. In comparison with similar studies, our achievement presents an` effective and inexpensive solution because its operating principle is based on radio frequency transmission, so it works perfectly even in the absence of the internet. Finally, our study was very well tested without detecting any abnormalities, and the results obtained are a perfect witness to our success.

Microwave torrefaction of empty fruit bunch pellet: Simulation and validation of electric field and temperature distribution

Microwave simulation is significant in identifying a reactor design allowing the biomass to be heated and processed evenly. This study integrated the radio frequency and transient heat transfer modules to simulate the microwave distribution and investigated the performance of microwave heating in the cavity. The simulation results were compared with the experimental findings using the finite element analysis software of COMSOL MULTIPHYSICS to predict the temperature profile and electric field of microwave in the biomass (empty fruit bunch pellets). The higher temperature distribution was observed at the bottom and centre section of the empty fruit bunch pellet bed in the reactor, showing the uniqueness of microwave heating. According to the simulation results, the temperature profile obtained through the specific cavity geometry and dielectric properties agreed with the experimental temperature profile. The simulated temperature profile demonstrated a logarithmic increase of 120 °C/min at the first 50 s followed by 50 °C/min until 350 s. The experimental temperature profile showed three different heating rates before reaching 300 °C, including 78.3 °C/min (50–120 °C), 30.6 °C/min (121–250 °C), and 105 °C/min (250–300 °C). The results of this study might contribute to the improvement of microwave heating in biomass torrefaction.

Nitrogen discharge characteristics and species kinetics in helicon plasma source

Nitrogen (N2) helicon plasma is produced with radio frequency (RF) right-helical antenna at low pressures. Several wave modes and their transitions of N2 helicon discharge are observed experimentally. Blue Core phenomenon is achieved at high magnetic fields and high RF powers, with strong local blue light emissions of N II lines and high electron temperature inside the core area. Based on actinometric ratio and pressure balance model, species kinetics of N2 helicon plasma are analyzed. It is shown that about 79% of N2 molecules are dissociated and about 49% of the neutrals are ionized inside the Blue core in high magnetic field of 850 G and RF power of 2200 W. Nearly 99% of N2 molecules inside the core area are depleted considering the neutral density before and after discharge, from 7.3 × 1013 cm−3 to 6.5 × 1011 cm−3. Serious neutral depletion of N2 and N neutrals and high electron temperature are suggested to be the dominant causes for significant enhancement of central N II emissions (blue lights). Meanwhile, evolution of reaction processes indicates that N ionization and N+ excitation become dominant in BC mode. Besides, external magnetic field is an important factor to control the discharge mode transitions as well as the radial distributions of plasmas. From the calculated results of dispersion relation, the cavity mode resonance, rather than antenna coupling resonance, of helicon waves plays a dominant role on the wave mode formation and RF energy coupling between RF antenna and plasma. The mode transition results from excitation of helicon wave of higher axial eigenmode. N2 helicon plasma shows different characteristics from argon in mode transition, spectral emission and Blue Core formation. It is due to the high dissociation energy of N2 molecules (9.8 eV) and extensive dissociation and ionization processes. This results in a higher RF power as well as magnetic field for helicon wave coupled mode in N2 helicon plasma than that in Ar plasma.

O116 / #219 NEUROMODULATION OF THE LINGUAL NERVE: A NOVEL TECHNIQUE AND CASE SERIES: TRACK 3: RESTORATIVE THERAPIES / NONINVASIVE STIMULATION / NEUROSTIMULATION FOR HEAD AND FACE PAIN

Acute injury of the trigeminal nerve or its branches by trauma or iatrogenic injury may result in post-traumatic neuropathy (PTN) of the trigeminal nerve. These patients suffer from a chronic and debilitating constellation of symptoms including paresthesias, allodynia, dysesthesias, or hyperalgesia. Treatments include medications, pulsed radiofrequency modulation, and microsurgical repair. Trigeminal nerve stimulation has been previously reported for trigeminal neuropathy, however V3 implantation is often avoided due to an elevated migration risk secondary to mandibular motion.

RF 모듈의 PHM 적용을 위한 가상데이터 생성 및 고장 분석 도구 개발

Purpose: This study proposes virtual data generation methods and develops a fault analysis tool for the prognostics and health management (PHM) of a radio frequency (RF) module, which is the main component used in electronic warfare devices.BRMethods: Current signals are assumed to be measured on the RF module and selected for virtual data generation. The three fault modes of the RF module are identified with help of an electronic warfare developer group.BRResults: The following fault modes are identified: 1) Delaying initial booting time, 2) continuously decreasing current, and 3) outlier of current signal. Accordingly, different types of signals are generated virtually, and the fault analysis tool is developed in the MATLAB software environment.BRConclusion: Virtual signal generation for different fault modes and its application in the analysis tool can be implemented for other types of electronic warfare as well. In addition, it can be applied to build prognosis models during the initial product development phase, despite the lack of field data.

60 GHz RF module with beam-steering optimization algorithm for high data rate access and backhaul communications

This paper presents an 802.11ad-based radio frequency module for high data rate fixed wireless access and backhaul communications. The transceiver chip is manufactured in SiGe BiCMOS technology covering 57–71 GHz, providing 16 RX and 16 TX paths with combined output power of more than 20 dBm. The chip is packaged using embedded wafer-level BGA technology of the size 12.6times 12.6times 0.8~{text{ mm }}^3 and employs advanced dielectric materials with 2 metallic redistribution layers. The package integrates the transceiver chip with RX and TX high gain PCB antenna arrays, allowing effective isotropic radiated power (EIRP) of more than 40 dBm. Beam steering is achieved in ± 50^{circ } by the transceiver through providing appropriate weights to the antenna arrays. The paper presents generation of beamforming lookup table along with optimization of the power distribution to the array. This optimization results in flattening of the EIRP over the whole beam-steering range and frequency bandwidth. The module allows for data rates up to 10 Gbps by employing full-channel 128 QAM and half-channel 256 QAM single-carrier modulation.

Real-Time GB-OFDM Signal Generation/ Reception Using Image Spectra and Undersampling for IMDD System

We proposed and experimentally demonstrated a low-complexity generation and reception scheme for guard-band orthogonal frequency-division multiplexing (GB-OFDM) in intensity-modulation and direct-detection (IMDD) transmission systems. The image spectra that arise in the 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> Nyquist zone from a digital-to-analog converter (DAC) operating in radio-frequency mode is exploited to efficiently generate GB-OFDM signal. In the receiver, the analog-to-digital converter (ADC) undersampling technique is applied to recover the baseband OFDM signal. The sampling rate of DAC/ADC is reduced and no electrical mixer and oscillators are required for up/down-conversions. Moreover, the same digital signal processing algorithms as the baseband OFDM can be applied to the proposed GB-OFDM. The proposed GB-OFDM scheme is experimentally investigated in a real-time short-reach IMDD system. The results exhibit that the receiver sensitivity in terms of the received optical power of the proposed real-time 16/64QAM-encoded GB-OFDM system over 50 km standard single-mode fiber can be improved by 7.5/3.5 dB at the bit error rate of 3.8e-3, compared to the baseband OFDM.

Guest Editorial Low-Cost Wide-Angle Beam-Scanning Antennas

One of the key antenna requirements in many modern wireless systems for communications and sensing is wide-angle beam-scanning <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . The traditional method to achieve wide-angle beam-scanning is to employ mechanically controlled reflectors or lenses, which are bulky, heavy, and suffer from slow beam scanning speed. Other important limitations of mechanical scanning antennas include the lack of multi-beam scanning capability and the ability to conform with non-planar structures (conformal geometries), which are essential in a number of emerging systems requiring very low-profile antennas. An alternative technique is to employ electronically beam-scanning antennas using passive or active phased arrays <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . Main disadvantages of phased arrays are high complexity, high power consumption, and high cost due to a large number of radio frequency (RF) or microwave phase shifters and T/R modules required. The problems worsen for phased arrays at millimeter-wave, sub-THz, and THz frequencies, due to significant losses in phase shifters and feed networks at higher frequencies combined with lower efficiency of power amplifiers <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> . The digital beamforming approach is even more costly and energy hungry due to the employment of large number of RF modules and digital devices <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> , <xref ref-type="bibr" rid="ref3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[3]</xref> , <xref ref-type="bibr" rid="ref4" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[4]</xref> .

Energy Harvest in Ferromagnet‐Embedded Surface Acoustic Wave Devices

AbstractSurface acoustic wave (SAW) filters are at the center of the radio frequency module in mobile terminals. With the increase of SAW frequency and the miniaturization of devices, the heat generation becomes prominent in SAW devices, providing a potential platform for thermal energy harvesting. Here ferromagnetic materials are embedded into SAW delay lines to demonstrate that thermal energy can be harvested to generate robust transverse electrical signals via anomalous Nernst effect, which are comparable with the anomalous Hall signals when an electric current is intensively applied. The transverse voltage exhibits nonreciprocal features, both amplitude and polarity are dependent on the propagation direction of SAW in contrast to its longitudinal counterpart, which only changes the amplitude but remains polarity with opposite SAW direction. The finding provides a different platform for thermoelectric energy conversion and opens a window for thermal energy harvesting and acoustic or heat flow sensing in SAW devices.