It is difficult to meet the design requirements of high-frequency surface acoustic wave (SAW) filters with low insertion loss and large bandwidth using conventional Rayleigh surface acoustic wave design. In this paper, a high-frequency broadband low insertion loss longitudinal leaky surface acoustic wave (LLSAW) filter based on multi-layer film structure has been designed. Firstly, the waveguide structure exciting the longitude leaky surface acoustic wave (LLSAW) is determined, and the 2D theoretical model of the device is established. Secondly, the influences of various electrode parameters on the spurious are studied. It is found that when the grating reflector of the series resonator is set to 6, the spurious in the passband can be suppressed as much as possible. Finally, the mirror T-type and mirror π-type filters are designed, and the performances are compared. The results show that the mirror T-type structure is more effective in suppressing the spurious response. The designed LLSAW filter with mirror T-type structure has a center frequency of 3 545 MHz, insertion loss of -1.416 dB, -3 dB bandwidth of 274 MHz, and out-of-band rejection of greater than -30 dB.

Using finite element simulation software, the film bulk acoustic resonator（FBAR） model was established. The study focused on investigating the effects of different electrode shapes (rectangular, trapezoidal, circular, and regular pentagonal) and apodization angles (30°, 36°, 40°, and 45°) on parasitic resonances under different resonant areas (3 600-10 000 μm2). The smith impedance curves and non-circularity values were obtained. The study also explored the suppression effects of stepped load structures on lateral acoustic wave leakage. The simulation results show that the non-regular pentagonal electrode shape with a apodization angle of 40° exhibits the best suppression effect on parasitic resonances. For the resonant area of 3 600 μm2, its non-circularity value is 6.45%, which is comparable to the rectangular electrode at a resonant area of 10 000 μm2. The designed stepped load structure significantly enhances the quality factor at the parallel resonance point. With a lateral dimension of 60 μm, the second-order electrode load structure achieves a quality factor of 1 378, which is 10.07% higher than that of the structure without electrode load.

The piezoelectric film has an inherent nonlinear hysteresis response to the piezoelectric effect, and the sound wave has a shear wave component that propagates toward the edge, both of which will cause energy loss of the sound wave. In this paper, a single-crystalline aluminum nitride thin film bulk acoustic wave resonator (SABAR) with an edge air layer structure is designed, which can reduce the electromechanical loss of nonlinear hysteresis, prevent the leakage of shear wave energy, and improve the quality factor of the resonator. COMSOL is used to conduct finite element simulation of the device, and a resonator with an edge air layer structure was successfully prepared for testing and verification.

A solution based on surface acoustic wave(SAW) tag is proposed for the parallel detection of soil temperature and moisture. The coupling-of-mode(COM) theory is used to model and simulate the impedance-loaded SAW tag, and the variation of the echo amplitude and phase of the load reflector with the capacitance value is obtained. On this basis, a dual channel double-sided tag structure is designed according to the different sensing mechanisms of SAW tag to soil temperature and moisture. The use of time-division multiple access(TDMA) method solves the problem of echo signal aliasing during detecting soil at different depth levels simultaneously. The soil temperature and moisture detection is implemented through the phase and amplitude ratio of the echo signal. The tag is tested using a vector network analyzer and a reader, and the test results show the effectiveness of the tag.

With the development of modern communication technology, the demand for high-performance RF devices becomes more and more urgent. BAW resonators meet the needs of high-frequency applications with their unique advantages and have become one of the hot research directions in the current RF devices. In this paper, a Lamb wave S0 mode BAW resonator based on interdigital electrodes is proposed, and the influence of supporting anchor structure and piezoelectric materials on the Q value of the device is discussed. The effects of the supporting anchors and piezoelectric materials on the quality factors of the device are discussed. The quality factors of devices with different four anchor structures and three piezoelectric materials are simulated and analyzed. At the same time, based on the aluminum nitride BAW resonator unit obtained by simulation, a BAW filter with a frequency band of 70.36-71.45 MHz is fabricated by trapezoidal cascade. The filter has the insertion loss of >-1 dB, which can be suitable for high-frequency and narrow-band applications.

The ternary piezoelectric ceramics of 0.54BiFeO3-0.33PbTiO3-0.13Ba(ZrxTi1-x)O3(BF-0.33PT-0.13 Ba(ZrxTi1-x)，0.4 ≤ x ≤ 0.8) were prepared by traditional solid-state reaction method and the effects of Zr content (x) on microstructure, dielectric, ferroelectric and piezoelectric properties of ceramics were investigated. X-ray diffraction results show that BF-0.33PT-0.13Ba (ZrxTi1-x) ternary ceramics display a single perovskite structure. When 0.4≤x≤0.7, the ceramic phase structure is tetragonal phase and rhombohedral phase coexist. When x=0.8, the ceramic has a triangular phase structure. Scanning electron microscopy (SEM) images show that the grain size increases with the increase of Zr content. The fluctuation of piezoelectric coefficient d33 of ceramics is less than ±6% at 25-400 ℃. When x=0.7, BF-0.33PT-0.13Ba (ZrxTi1-x) has the best comprehensive properties, and the dielectric constant εr, Curie temperature TC and piezoelectric constant d33 of the ceramics are 1 194 (1 kHz), 438 ℃ and 330 pC/N, respectively. The capacitance temperature coefficient and the change rate of piezoelectric constant d33 are 16% and 8% at 25-300 ℃, respectively. These results indicate that BF-0.33PT-0.13Ba (Zr0.7Ti0.3) ceramics have promising applications in high-temperature piezoelectric devices.

The 0.15BiScO3-0.85(Pb0.88Bi0.08)(Ti0.97Mn0.03)O3 (BSPT-Mn) high-temperature piezoelectric ceramics were prepared by traditional solid-state method in the sintering range of 1 125-1 175 ℃. All samples are pure phase, and the distribution of grain sizes follows the normal distribution pattern. The dopant elements are uniform and no significant enrichment phenomenon is observed. The results show that the BSPT-Mn high-temperature piezoelectric ceramic prepared by sintering at 1 150 ℃ achieved a maximum mechanical quality factor of 1 500.3, and exhibited good piezoelectric properties with dielectric constant d33 of 289.8 pC/N at a working temperature of 484.4.

The high reliability LC filters with ceramic substrate integrated package were fabricated by using the reflow soldering method. The resistance spot welding process was used to fix the pins of the winding inductor, and the chip capacitors were fixed by SMT red adhesive, thus the pre-fixation of the internal components in the ceramic substrate integrated packaging LC filter was achieved. The solder paste was added by coating and the well wetted welding spots were formed, the residual flux was removed and cleaned by using the micro-pressurized water column. After debugging and glueing to fix the wound inductor, the parallel seam welding is used implement the product packaging. The process inspection, temperature and mechanical test of the LC filter fabricated by reflow soldering assembly were carried out. The results show that the LC filter fabricated by proposed assembly process have good process through rate, meet the requirements of high reliability environmental applications, and are suitable for mass production.

An optical image stabilization platform is designed utilizing the characteristics of fast response, high positioning accuracy and good control performance of piezoelectric motor. The finite element simulation of the motor stator is carried out by COMSOL, and the working principle and response characteristics of the stator are analyzed. The optimum operating frequency and pre-pressure of the motor are measured by experiments, and the relationship among the response speed and the excitation voltage, operating frequency and pre-pressure is analyzed. A variety of control methods are used for positioning test and the high-precision positioning control with error of less than 250 nm has been realized by using a composite control of PID and stepping.

In this paper, a differential pressure fiber Bragg grating (FBG) static level meter is designed based on the basic principles of FBGs and connectors to achieve accurate and effective monitoring of the uneven settlement of building structures. The theoretical derivation, calibration tests and static characteristic analysis of the level meter are carried out. The experimental results show that the sensitivity of the level meter is 6.5 pm/mm, the linear fitting degree R2 is 0.999, non-linear error is 1.48%, hysteresis error is 0.74%, and repeatability error is 5.72%, resulting in a total accuracy of 5.95%. In order to increase the sensitivity of the level meter, the original corrugated diaphragm was improved and analyzed. The results showed that the sensitivity of the improved level meter was 11.87 pm/mm, which was about 1.8 times higher than the unimproved one. The settlement of buildings has been effectively monitored by using this type of level meter structure, providing effective technical support for the health monitoring of building structures.

In the field of flow metering, there is relatively little research on vortex flow measurement using fiber optic sensing technology, so it has important research significance. The paper designed a cantilever beam type fiber Bragg grating vortex flow sensor is designed, which utilizes the vibration of the free end of the cantilever beam to periodically shift the center wavelength of the fiber Bragg grating, thereby measure the vortex frequency and get the fluid flow information. The temperature sensing test and flow sensing test are carried out. The results show that the temperature sensitivity of the sensor is 17 pm/℃, the vortex flow sensitivity is 0.018 95 Hz/（L·h-1）, and the nonlinear error is 2.23%, which verifies that the sensor can be applied to measure the liquid vortex flow.

In the context of active optical systems employing piezoelectric actuators as actuation mechanisms, effectively modeling and correcting the inherent hysteresis nonlinearity in piezoelectric actuators is essential for enhancing system performance. The paper presents an efficient identification and modeling approach for the nonlinear hysteresis dynamics of piezoelectric actuators with deformable mirror loads. The proposed method was successfully applied in the identification and modeling of hysteresis for piezoelectric actuators with mirror loads, reducing the runtime of the identification algorithm by over 90% with a relative error less than 1.886 7%. Furthermore, this approach overcomes the challenge of low signal-to-noise ratio resulting from the structure. Experimental results demonstrate that the piezoelectric hysteresis model obtained through this methodology can effectively compensate for and correct errors induced by the dynamic hysteresis nonlinearity of piezoelectric actuators. By utilizing a feedforward controller, the mirror surface positioning errors caused by piezoelectric hysteresis are reduced by 56.21%, significantly enhancing overall system performance.

In order to solve the problem of small deflection angle of the fast reflector driven by piezoelectric actuator having a small elongation, a new design scheme for the fast reflector is proposed in this paper. A three-level lever type flexible hinge amplification mechanism is used to amplify the displacement of the piezoelectric actuator, and a flexible bearing is used as the motion joint to achieve large angle fixed axis deflection of the fast pendulum mirror. The r theoretical derivation and finite element simulation are used to analyze the maximum deflection angle, equivalent stress, resonant frequency and vibration mode of the fast swing mirror. The experimental results show that the designed fast pendulum mirror can achieve mirror deflection of greater than 2mrad, meeting the requirements of wide range and high-precision beam positioning.

The piezoelectric resonators are the basic components for measuring the properties of piezoelectric materials. Based on the microwave network theory and characteristics of piezoelectric resonators, a method for measuring the equivalent circuit parameters of piezoelectric resonators using network analyzer and capacitance tester was proposed in this paper. The relationships between equivalent circuit parameters and resonant frequency, anti-resonant frequency and insertion loss were derived. Three kinds of piezoelectric resonator samples were made. The performance parameters of these three samples were measured by network analyzer and capacitance tester. The equivalent circuit parameters of piezoelectric resonators were calculated. Finally, the transmission curve of the measured equivalent circuit was measured by using the microwave simulation software, which was consistent with the measured curve, thus verifying the effectiveness of the method. Compared with the traditional method, the proposed method has the advantages of high-speed and simplicity.

The basic structure of a novel MEMS gyro based on bidirectional thermal expansion flow is proposed and its sensitive mechanism is revealed. The finite element method and CMOSOL are used to establish a three-dimensional model, and the temperature field of the bidirectional thermal expansion flow gyro sensitive element is calculated. The calculation results show that the bidirectional thermal expansion flow gyroscope exhibits gyroscopic effect, and the temperature sensitivity of the gyroscope is 1.577 K·（rad/s）-1, the sensitivity is 0.064 V·（rad/s）-1, and the nonlinearity is 6.855% when the input power is 70 mW and the input angular velocity ranges from -25-25 rad/s. The gyro is characterized by high sensitivity, low suppression cross-coupling and simple structure, and can be used in the fields of electronic equipment, aerospace and medical instruments etc.

In order to improve the accuracy and reliability of electronic compass heading angle measurement, a multi magnetometer electronic compass architecture is proposed, and an error compensation and fusion algorithm based on Recursive Least Squares (RLS) combined with Kalman Filter (KF) is designed using the spatial constraints of the geomagnetic field and magnetometer. Firstly, a multi magnetometer error model is constructed based on the measurement error characteristics of the geomagnetic field, and RLS is used for ellipsoidal fitting to obtain error compensation parameters. Then, KF iterative fusion is performed on isomorphic multi-sensor data based on the noise covariance matrix. Finally, simulation and actual experiments have verified the effectiveness of the multi magnetometer model and compensation fusion algorithm. The final heading angle measurement accuracy is within ±0.5°, with a standard deviation of less than 0.2°, which is about three times higher than that of a single magnetometer.

The magnetic field coil is the core part of the magnetic field system of the nuclear magnetic resonance gyroscope (NMRG). It is also the core component of the inert gas magnetic resonance excitation maintenance and active magnetic compensation. The coupling of transverse magnetic field coil has great influence on the accuracy of magnetic compensation and magnetic resonance excitation. Therefore, it is very important to calibrate the coupling of the transverse magnetic field coil. In order to solve the above mentioned problems, a coupling calibration method of transverse magnetic field coil based on the built-in magnetometer of NMRG is proposed. The correctness and feasibility of this method are verified by theoretical simulation and experimental design. The experimental results show that the proposed coupling calibration method is used to calibrate the X-to-Y-axis coupling and Y-to-X-axis coupling, with values of 1.86% and 3.11%, respectively. By rotating the coil to change the assembly angle, it is shown that the measurement results are not affected by the assembly error when the rotation angle is small. By calibrating a total of 5 coils from the same batch, the coil with less coupling is selected for assembly according to the results, which provides a basis for the selection of NMRG coil.

A CPW-fed quaternary ultra-wideband (UWB) high isolation antenna based on FR4 is proposed in this paper. The antenna consists of four cell slot antennas with overall size of 65 mm×65 mm×0.8 mm. The ultra-wideband characteristics of the antenna are achieved through the use of defective ground structures and corner cuts. The unit antennas are placed vertically to each other to achieve polarization diversity, at the same time; an isolation fence structure is loaded in the middle of the antenna, which greatly increases the isolation of the antenna. The antenna was fabricated and tested. The test results show that the proposed antenna can cover the frequency of 2.86-11.1 GHz and the isolation is greater than 20 dB in the band. It has the characteristics of high isolation, ultra-wideband and low envelope correlation coefficient (ECC<0. 006). The antenna adopts the CPW feeding, which is easier to apply in integrated circuits and suitable for various ultra-wideband systems.

A frequency reconfigurable multiple input multiple output (MIMO) antenna based on a novel coplanar waveguide (CPW) is designed in this work. The switching elements are used in the antenna to achieve the discrete frequency tunability of discrete frequencies of 6.17-9.38 GHz and 19.53-25.48 GHz by controlling the switch to change the current length of the CPW. The conversion mode does not require additional matching circuits, resulting in a more compact structure. The antenna unit is CPW-fed and etched on the dielectric substrate of F4B, and the MIMO configuration can achieve good isolation without additional decoupling devices. The simulation and test results show that both the single antenna and the MIMO antenna can realize the frequency reconfiguration characteristics. Tthe isolation between antenna units is <-20 dB, the correlation envelope coefficient is <0.05, and the diversity gain is close to 10 dB, which meets the design requirements.

The acoustic emission sensors are widely employed in the partial discharge detection, but those based on PZT piezoelectric ceramics are difficult to meet the increasing demands for sensitivity and bandwidth simultaneously. This study designs a dual-resonance acoustic emission sensor using high-performance ferroelectric single crystal PMN-PT as the piezoelectric vibrator. The resonant peak coupling is used to improve the sensitivity and bandwidth simultaneously. The fabricated sensor demonstrates a remarkable sensitivity of 76.2 dB, along with a wide bandwidth of 20 kHz to 105 kHz. It exhibits excellent stability, surpassing PZT-5H-based acoustic emission sensors in sensitivity and signal-to-noise ratio.

To solve the sensitivity and nonlinearity of pressure sensor of microelectromechanical system (MEMS), Proposed a beam-composite membrane-island pressure-sensing structure, Optimize the overall structure size to obtain the maximum horizontal stress difference and deflection, Doping type, doping concentration, structure size and distribution position, And comparing the beam-composite membrane-island structure with the output of conventional structures, According to the simulation results, the sensitivity of beam-composite membrane-island structure in the range of 0-60 kPa pressure is increased by more than 7% higher than the related structure and 2 times higher than the E-type structure, The nonlinearity of 0.029% FSS, Meet the requirements of high sensitivity and high linearity of MEMS micro pressure pressure sensor, It can support the relevant applied research in the medical field.

In order to improve the output performance of the piezoelectric pump, a flexible duckbill valve piezoelectric pump is designed according to the duckbill structure form. Firstly, the structure and working principle of the flexible duckbill valve piezoelectric pump are described; secondly, the output flow rate and output pressure of the flexible duckbill valve piezoelectric pump are theoretically analyzed; finally, the flexible duckbill valve piezoelectric pump prototype is made, and the change rules of the flow rate as well as the difference between the inlet and outlet pressures are investigated. The experimental results show that the maximum pressure difference between the inlet and outlet of the flexible duckbill valve piezoelectric pump can be up to 15.5 kPa driven by 220 V, 45 Hz sinusoidal alternating current; the maximum flow rate of the flexible duckbill valve piezoelectric pump is 39 mL/min driven by 220 V, 55 Hz sinusoidal alternating current. The results verify that the flexible duckbill valve piezoelectric pump has good conveying capacity.

In order to avoid the damage of PZT of galloping energy harvester under high flow rate and ensure stable output characteristics in complex working environment, a galloping piezoelectric-electromagnetic energy harvester (GPEEH) using magnetic force to control the vibration amplitude of cantilever beam is proposed in this paper. The introduced nonlinear magnetic force can control the amplitude of the bluff body, improve the output stability of PEH, improve its adaptability to high wind speed environment, and increase the output voltage of the composite energy harvester. The influences of different load resistance, wind speed, key structural parameters d0 and d1 on the output characteristics of the energy harvester are investigated by using the fabricated wind tunnel experimental platform and the experimental prototype. The experimental results show that when the amplitude of the PEH bluff body is limited to a certain range by the magnetic force, the vibration frequency and velocity of the bluff body gradually increase with the increase of the wind speed. The main frequency of PEH vibration (6.3 Hz) at wind speed of 11.5 m/s is 1.4 times that of PEH vibration (4.3 Hz) at wind speed of 8.4 m/s. The output power of GPEEH is 6.18 mW at wind speed of 12 m/s, which is 47% higher than that of a single galloping piezoelectric energy harvester. When the wind speed reaches 10.5 m/s, the output power of PEH and EEH tends to be stable.

Aiming at the problem of poor positioning and quantification of internal defects in ultrasonic testing of composite insulators caused by high acoustic attenuation, the total focus method (TFM) is used to improve the detection quality. Based on the k-Wave toolbox, the simulation of ultrasonic total focus detection of internal defects of composite insulators is carried out. The effects of frequency, number of phased array elements, defect size and other factors on the detection results are discussed and the detection experiments are carried out. The results show that the full focusing method is effective in detecting the internal defects of composite insulators. The frequency has a great influence on the detection results. When the frequency is larger, the penetration force of the ultrasonic wave is weakened, and the attenuation coefficient of the ultrasonic wave in the composite insulator is increased. When the smaller frequency is selected, the detection resolution of the probe is reduced, which affects the quantification of the defect. Therefore, the appropriate frequency should be selected when detecting the composite insulator. The imaging effect of the 2.5 MHz frequency is the best among the four different frequencies. The number of array elements and defect size have little effect on the detection results. In the actual detection, the appropriate number of array elements should be selected according to the actual engineering needs. The research results provide a theoretical basis for the ultrasonic total focus method to detect the internal defects of composite insulators.