Miniaturized integrated package deep-sea synthetic aperture sonar transducer array

Abstract

The application relates to a miniaturized integrated packaged deep-sea synthetic aperture sonar transducer array, which is applied to the technical field of deep-sea terrain mapping. The deep-sea synthetic aperture sonar transducer array comprises a high-frequency transmitting module, a high-frequency receiving module and a mounting base. A pressure compensation assembly composed of a customized filling medium and a buffer cavity is arranged in the transmitting module shell of the high-frequency transmitting module; a spliced receiving array and a front-end signal preprocessing circuit are arranged in the receiving module shell of the high-frequency receiving module, subarrays are embedded with sub-elements at joints, and an isolation reinforcing rib network is embedded between the front-end signal preprocessing circuit and the spliced receiving array. The transmitting module shell and the receiving module shell are fixed to the mounting base in a clamping mode with damping pads and are arranged with gaps.

Description

Technical Field

[0001] This invention belongs to the field of deep-sea topographic mapping technology, specifically relating to a miniaturized integrated packaged deep-sea synthetic aperture sonar transducer array. Background Technology

[0002] Existing deep-sea sonar arrays employ a design that integrates the transmitting and receiving transducers within the same pressure-resistant metal platform or continuous shell. To withstand the hydrostatic pressure of deep water, a common approach is to increase the shell thickness and fill the internal cavity with conventional insulating oil to create a pressure-balancing medium. When constructing large-sized acoustic receiving apertures, multiple short piezoelectric ceramic arrays are typically assembled by directly connecting them using mechanical flanges or a rigid metal frame.

[0003] However, as deep-sea exploration equipment evolves towards miniaturization of the carrying space, extreme depth of exploration, and finer imaging resolution, sonar transducer arrays face extremely complex multi-field environmental interference within a limited three-dimensional profile.

[0004] Therefore, how to balance the adaptability to high dynamic pressure gradients in deep water, the stability of weak echo signal sensing, and the accuracy of acoustic spatial sampling under strict spatial size constraints is a common technical challenge in the current engineering application of deep-sea sonar equipment. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a miniaturized, integrated, and packaged deep-sea synthetic aperture sonar transducer array.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: a miniaturized, integrated, and packaged deep-sea synthetic aperture sonar transducer array, comprising: The high-frequency transmitting module has a transmitting module housing, a transmitting array is arranged on the radiating surface of the transmitting module housing, and a pressure compensation component is arranged inside the transmitting module housing. The pressure compensation component is configured to shrink in volume and displace fluid in response to the external deep-sea dynamic transmission pressure, so as to offset the compression volume of the transmitting module housing caused by the external seawater pressure, thereby dynamically balancing the transient pressure difference between the inside and outside of the transmitting module housing. The high-frequency receiving module has a receiving module housing, and the receiving module housing contains a splicing receiving array and a front-end signal preprocessing circuit. Mounting base, the transmitter module housing is fixed to the mounting base through the transmitter end mounting hole, and the receiver module housing is fixed to the mounting base through the receiver end mounting hole; In the assembled state, the transmitter module housing and the receiver module housing are arranged one behind the other in a straight line in the horizontal direction, with the rear end face of the transmitter module housing facing the front end face of the receiver module housing, and a gap is maintained between the two facing end faces.

[0007] Preferably, damping pads are sandwiched between the connection interfaces of the transmitting module housing and the mounting base, and between the connection interfaces of the receiving module housing and the mounting base.

[0008] Preferably, the pressure compensation assembly includes a buffer chamber and a customized filling medium; The buffer cavity is located inside the housing of the transmitting module in a non-acoustic working area away from the acoustic radiation surface; A custom filling medium is used to fill the remaining space inside the transmitter module housing and completely encapsulate the transmitter array. The custom filling medium is made of a mixture of hollow glass microspheres and modified silicone oil.

[0009] Preferably, the volume doping ratio of hollow glass microspheres in the customized filling medium is obtained by solving the equivalent bulk modulus model; The lower limit of the fixed volume of the buffer chamber is limited to the total volume deformation of the customized filling medium under the maximum water pressure condition, and the upper limit of the fixed volume of the buffer chamber is limited to 1.2 times the total volume deformation.

[0010] Preferably, the transmitting array includes multiple independent longitudinal oscillators, which are made of piezoelectric ceramic material and are arranged in a one-dimensional linear array at equal intervals along the long side of the transmitting module housing.

[0011] Preferably, the splicing receiver array is installed on the acoustic receiving surface of the inner wall of the receiver module housing. The splicing receiver array includes two receiver subarrays with the same structural dimensions. The receiver subarray includes multiple receiver elements, and the center arrangement spacing between the receiver elements is arranged according to the upper limit threshold of the anti-loudsweep acoustic constraint equation.

[0012] Preferably, a sub-element is embedded at the mechanical joint formed by the docking of the two receiving subarrays. The sub-element is made of the same piezoelectric composite material as the receiving element and is not equipped with signal lead-out electrodes.

[0013] Preferably, the front-end signal preprocessing circuit is attached to the back side area of ​​the splicing receiving array; The signal output pins of the receiving subarray are directly connected to the differential signal input of the front-end signal preprocessing circuit via microstrip lines.

[0014] Preferably, the receiver module housing is equipped with an isolation reinforcing rib network; The isolation reinforcing rib network is embedded in the structural gap between the front-end signal preprocessing circuit and the backing of the splicing receiver array.

[0015] Preferably, the isolation reinforcing rib network is made of titanium alloy and configured as a three-dimensional topological mesh. The first end face of the isolation reinforcing rib network abuts against the heat-generating and heavy-load area of ​​the front-end signal preprocessing circuit, and the second end face of the isolation reinforcing rib network abuts against the metal inner wall of the receiving module housing; The internal metal mesh of the isolation reinforcing rib network has an acoustic impedance staggered layered arrangement in a direction perpendicular to the sound wave propagation path.

[0016] This invention addresses the shortcomings of the prior art and has the following beneficial effects: 1. The high-frequency transmitting module and the high-frequency receiving module are each independently packaged, and damping pads are sandwiched between the connection interfaces of the transmitting module housing, the receiving module housing, and the mounting base. This independent packaging and gap-retaining arrangement interrupts the continuous solid-medium path between the transceiver module end faces, and the damping pads dissipate the energy of mechanical vibration waves through shear and compression deformation. The independent packaging combined with the damping pad arrangement attenuates the vibration energy transmitted from the low-frequency mechanical vibrations generated during the operation of the high-frequency transmitting module to the high-frequency receiving module. Compared to the solid-borne interference generated by integrating the transmitting and receiving arrays within a continuous housing in existing technologies, this invention weakens the structural disturbance caused by strong mechanical impacts during the signal extraction process of the high-frequency receiving module, eliminates mechanical interference generated by high-power front-end transmission, and maintains the environmental stability for the high-frequency receiving module to acquire weak echo signals.

[0017] 2. The launch module housing is internally equipped with a pressure compensation component consisting of a buffer chamber and a customized filling medium. When subjected to external deep-sea dynamic pressure, the customized filling medium actively contracts in volume and generates fluid displacement into the reserved buffer chamber. The fluid compensation process, linked between the buffer chamber and the customized filling medium, offsets the compression of the launch module housing caused by external seawater pressure, balancing the transient pressure difference between the inside and outside of the launch module housing. Compared to the pressure transmission hysteresis and thin-walled shell deformation caused by filling with a single conventional oil in existing technologies, this invention transforms the external environmental pressure into an elastic deformation absorption process of the internal fluid medium. This avoids the destructive shear force exerted on the internal longitudinal oscillators by the inward deformation of the launch module housing, eliminates the risk of shell crushing and array element breakage during high-dynamic diving, and maintains the structural integrity of the high-frequency launch module.

[0018] 3. Sub-elements without signal output electrodes are embedded at the mechanical joint formed by the docking of two receiving subarrays in the spliced ​​receiving array. These sub-elements and the receiving subarrays have identical acoustic impedance characteristics, preventing abnormal scattering and diffraction of incident sound waves when crossing the mechanical joint area. The array splicing structure with sub-elements embedded at the mechanical joint fills the acoustic structural void caused by structural breaks, making the two disconnected receiving subarrays equivalent to a continuous acoustic aperture array at the external sound field perception level. Compared to the acoustic phase discontinuity caused by direct rigid docking of multiple array segments in existing technologies, this invention suppresses beam aliasing and distortion of high-frequency acoustic echoes during the spatial sampling stage, maintains a smooth transition of the sound field spatial phase, and ensures the accuracy of the high-frequency receiving module in acquiring the original acoustic characteristics of a large-scale continuous aperture.

[0019] 4. An isolation reinforcing rib network is embedded in the structural gap between the front-end signal preprocessing circuit and the backing of the splicing receiving array. This network forms a low thermal resistance heat conduction path, directionally conducting accumulated heat flow from the circuit to the outside of the receiving module housing for dissipation. Simultaneously, the staggered acoustic impedance layering structure of the internal metal mesh blocks the straight transmission path of mechanical waves, promoting diffuse reflection and phase cancellation of mechanical vibration energy. The isolation reinforcing rib network embedded in a specific gap constructs an isolation boundary for thermodynamic directional dispersion and acoustic shielding within the narrow, enclosed assembly space. Compared to the heat accumulation and electromechanical interference problems arising from high-density integration in existing technologies, this invention curbs the increase in thermal noise from electronic components and the depolarization phenomenon of piezoelectric composite materials, blocks the impact of internal self-excited vibrations on the circuit board, and ensures the stability of the high-frequency receiving module during in-situ extraction of weak electrical signals.

[0020] 5. The independently packaged transmitter module housing, receiver module housing, pressure compensation component, sub-element, and isolation reinforcement network work synergistically. The decoupled independent housing adapts to the spatial size limitations of the side of the deep-sea exploration equipment. The pressure compensation component maintains the shell shape of the high-power transmitter under the high dynamic pressure gradient in deep water. The sub-element and isolation reinforcement network together eliminate acoustic breaks and thermoacoustic crosstalk inside the receiver. The structural cooperation between the transmitter module housing, receiver module housing, pressure compensation component, sub-element, and isolation reinforcement network enables the invention to overcome the technical conflicts of deep-water dynamic extrusion stress, long array processing limitations, and in-situ high-density integration. It achieves the continuous, non-interfering operation of the high-power radiation operation of the high-frequency transmitter module and the high-fidelity signal extraction operation of the high-frequency receiver module within the same mounting boundary. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of the deep-sea synthetic aperture sonar transducer array. Figure 2 This is a schematic diagram of the longitudinal cross-sectional structure of the high-frequency transmission module; Figure 3 This is a schematic diagram of the longitudinal cross-sectional structure of the high-frequency receiving module; Figure 4 This is a schematic diagram of a partial assembly structure of the receiving element and the isolation reinforcing rib network; In the diagram: 1. High-frequency transmitting module; 11. Transmitting module housing; 12. Transmitting array; 131. Buffer cavity; 132. Custom filling medium; 14. Input connector; 2. High-frequency receiving module; 21. Receiving module housing; 221. Receiving subarray; 222. Sub-element; 23. Front-end signal preprocessing circuit; 24. Isolation reinforcing rib network; 25. Output connector; 3. Mounting base; 31. Damping pad. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0024] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0025] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0026] Unless otherwise specified, all raw materials described below may be commercially available or prepared using conventional methods in the art.

[0027] Application Overview: The existing technical contradiction of deep-sea sonar arrays lies in the fact that static engineering design cannot adapt to highly dynamic multi-field coupling environments. On the one hand, miniaturization requires compressing the shell thickness and internal volume, resulting in conventional fluid-sealed structures exhibiting lag in response to the high dynamic pressure gradients of the deep sea. Furthermore, the extremely compact space makes it easy for mechanical resonance generated by high-power transmitters to intrude into the high-sensitivity receiver. On the other hand, the mechanical splicing breaks of long-scale acoustic arrays disrupt the spatial continuity of sound field sampling and forcibly seal and concentrate weak signal processing circuits and heat-generating elements, leading to severe heat accumulation and electromechanical interference.

[0028] To address the aforementioned issues, this invention independently packages the high-frequency transmitting and receiving modules and establishes an indirect coupling path with energy attenuation characteristics. This is combined with a pressure compensation component based on bulk modulus matching introduced at the transmitting end, and an acoustic spacer element and a multi-field isolation reinforcement network configured at the receiving end. This invention abandons the conventional approach of passive pressure resistance and rigid isolation. It transforms passive pressure resistance into active fluid contraction compensation within the transmitting module housing, and compensates for structural breakpoints within the receiving module housing, constructing a microenvironment boundary with thermodynamic directional divergence and acoustic shielding. This achieves continuous and stable sensing of deep-sea broadband detection signals while meeting stringent carrier spatial constraints.

[0029] Exemplary device: A miniaturized, integrated, packaged deep-sea synthetic aperture sonar transducer array includes: The high-frequency transmitting module 1 has a transmitting module housing 11, a transmitting array 12 is arranged on the radiating surface of the transmitting module housing 11, and a pressure compensation component for balancing transient water pressure is arranged inside the transmitting module housing 11. The high-frequency receiving module 2 has a receiving module housing 21, and the receiving module housing 21 is equipped with a splicing receiving array and a front-end signal preprocessing circuit 23.

[0030] When the aforementioned deep-sea synthetic aperture sonar transducer array is in operation, the high-frequency transmitting module 1 radiates high-frequency broadband sound waves into the deep-sea environment through the transmitting array 12, and relies on the internal pressure compensation components to resist the impact of external high dynamic water pressure; the high-frequency receiving module 2 obtains long-baseline acoustic echoes through the splicing receiving array, and uses the internally co-encapsulated front-end signal preprocessing circuit 23 to extract, condition and amplify weak signals nearby.

[0031] Example 1: In deep-sea topographic mapping applications at depths of up to 6000m, the space on the side of an unmanned underwater vehicle (UUV) has strict dimensional boundary conditions. High-resolution imaging requirements necessitate a long receiving aperture for the synthetic aperture sonar receiver, while deep-sea detection requirements demand a high-power transmitter.

[0032] When a transmitter generates high-frequency sound waves by applying a kilovolt-level driving voltage, it also generates low-frequency structural resonance and mechanical shock. If the transmitting and receiving arrays are integrated into a single continuous housing and encapsulated in a unified structure, the structural resonance and mechanical shock generated by the high-power transmitter will be directly conducted to the receiving end along the continuous metal housing medium. The high-frequency receiving array has extremely high receiving voltage sensitivity, and the intrusion of mechanical vibration waves will cause solid-borne interference waves to be superimposed on the received signal, covering the originally weak seabed echo signal and reducing the signal-to-noise ratio of the sound field perception.

[0033] To cut off the direct transmission path of mechanical vibration waves and provide an external attachment point, the transceiver structure needs to be decoupled and divided into independent packages, and an indirect coupling path with energy attenuation characteristics needs to be established at the mounting interface. When establishing this indirect coupling path, the hydrostatic pressure generated by the external seawater environment reaches as high as 60 MPa. Conventional elastic buffer components undergo nonlinear volumetric compression deformation under this 60 MPa hydrostatic pressure. This nonlinear volumetric compression deformation causes differentiated structural displacements in the independently arranged transmitter and receiver module housings, disrupting the coplanar alignment of the first transmitter and receiver faces. This disruption alters the geometric continuity of the fluid contact surface, causing boundary layer separation at the gaps in deep-sea navigation fluids and generating hydrodynamic noise interference. Maintaining the coplanar alignment of the first transmitter and receiver faces under 60 MPa pressure, while simultaneously cutting off the transmission path of low-frequency mechanical vibrations along the solid medium, constitutes the constraint on the decoupling and packaging configuration of the transceiver structure.

[0034] like Figure 1 As shown, the deep-sea synthetic aperture sonar transducer array includes an independent high-frequency transmitting module 1 and a high-frequency receiving module 2, as well as a mounting base 3 that provides a mounting point.

[0035] like Figure 1 , Figure 2As shown, the high-frequency transmitting module 1 has a transmitting module housing 11, which is configured as a short strip with a length of 150mm, a width of 60mm, and a height of 50mm. The high-frequency transmitting module 1 has a first transmitting end face facing the external seawater medium and a second transmitting end face facing away from the external seawater medium. An input connector 14 extends from the non-acoustic radiation area of ​​the first transmitting end face of the transmitting module housing 11, forming a conductive channel for introducing high-power drive electrical signals. A transmitting end mounting hole is provided on the second transmitting end face of the transmitting module housing 11 for connecting the transmitting module housing 11 to the mounting base 3.

[0036] like Figure 1 , Figure 3 As shown, the high-frequency receiving module 2 has a receiving module housing 21, which is configured as a long strip with a length of 1100mm, a width of 60mm, and a height of 50mm. The high-frequency receiving module 2 has a first receiving end face facing the external seawater medium and a second receiving end face facing away from the external seawater medium. Multiple output connectors 25 are led out from the non-acoustic radiation area of ​​the receiving module housing 21, forming a conductive channel for exporting weak echo signals. A receiving end mounting hole is provided on the second receiving end face of the receiving module housing 21 for connecting the receiving module housing 21 to the mounting base 3.

[0037] Mounting base 3 is fitted and fixed to the external interface of the side of the unmanned underwater vehicle. The transmitter module housing 11 is fixed to mounting base 3 via transmitter mounting holes, and the receiver module housing 21 is fixed to mounting base 3 via receiver mounting holes. In the assembled state, the transmitter module housing 11 and receiver module housing 21 are arranged in a straight line along the horizontal direction, with the rear end face of the transmitter module housing 11 facing the front end face of the receiver module housing 21, maintaining a pre-defined structural isolation gap between the opposing end faces. The first transmitter end face and the first receiver end face are on the same horizontal plane, forming a flush acoustic working surface.

[0038] To balance the smooth fluid transition during deep-sea navigation with the isolation effect of low-frequency mechanical vibration waves, the structural isolation gap between the opposite end faces of the transmitting module housing and the receiving module housing is preferably 1mm to 5mm. In a preferred configuration of this embodiment, the structural isolation gap is set to 2mm to avoid hydrodynamic noise caused by boundary layer fluid separation due to excessive gap, and to cut off the rigid contact that may occur between the transceiver modules under slight deformation under pressure.

[0039] like Figure 1As shown, a damping pad 31 is clamped between the second transmitting end face of the transmitting module housing 11 and the connection interface of the mounting base 3. Similarly, a damping pad 31 is clamped between the second receiving end face of the receiving module housing 21 and the connection interface of the mounting base 3. The damping pad 31 is a viscoelastic buffer structure, possessing both the energy dissipation characteristics of viscous fluids and the deformation recovery characteristics of elastic solids.

[0040] During deep-sea topographic mapping, the main control cabin of the unmanned underwater vehicle (UUV) continuously inputs electrical signals to the high-frequency transmitting module 1 via input connector 14. The high-frequency transmitting module 1 receives the electrical signals and converts them into high-frequency broadband sound waves at a frequency of 150kHz, which are then radiated towards the deep-sea seabed surface via the first transmitting end. Upon contact with the seabed topographic boundary, the high-frequency broadband sound waves undergo diffuse reflection, generating echo signals carrying spatial characteristic parameters. The high-frequency receiving module 2, located behind the high-frequency transmitting module 1 and arranged in a straight line in the horizontal direction, senses the echo signals through its first receiving end face. The high-frequency receiving module 2 converts the captured echo signals into weak electrical signals, which are then transmitted back to the UUV's main control cabin via output connector 25 for synthetic aperture signal calculation.

[0041] The arrangement of the transmitting module housing 11 and the receiving module housing 21 with a structural isolation gap cuts off the continuous solid medium between the transceiver module end faces, eliminating the path for mechanical vibration waves to directly cross the housing. The damping pad 31 and the mounting base 3 cooperate to establish an indirect coupling connection path between the transceiver modules. The low-frequency mechanical vibration generated by the high-frequency transmitting module 1 is transmitted to the second transmitting end face, causing the damping pad 31 at the bottom of the high-frequency transmitting module 1 to undergo shear and compression deformation, converting some of the mechanical vibration energy into heat energy. The residual vibration energy after initial attenuation enters the mounting base 3 and is further attenuated during transmission. When the residual vibration energy reaches the bottom of the high-frequency receiving module 2, the damping pad 31 at the receiving end deforms again to consume energy, making the vibration energy that finally reaches the receiving module housing 21 approach zero. The attenuation of the damping pad 31 allows the receiving end to maintain a weak signal sensing environment without mechanical interference.

[0042] Both the transmitter module housing 11 and the receiver module housing 21 have a width of 60mm and a height of 50mm. Their cross-sectional dimensions are identical, and they are arranged in a straight line along the horizontal direction. Combined with the flush arrangement of the first transmitter and receiver faces, this maintains a continuous cross-sectional profile on the longitudinal water-facing surface. When the unmanned underwater vehicle (UUV) navigates in deep water, the external seawater flows smoothly from the transmitter module housing 11 to the surface of the receiver module housing 21, avoiding fluid stagnation points or turbulent vortices in the junction area between the transmitter and receiver modules. This consistent and flush straight-line arrangement accommodates the side-mounted space dimensions of the UUV while reducing fluid resistance during deep-sea navigation and minimizing hydrodynamic noise interference caused by fluid separation.

[0043] Example 2: In deep-sea topographic mapping applications, the vertical speed of the unmanned underwater vehicle when performing a diving maneuver can reach up to 1.5 m / s, the diving depth can reach 6000 m, and the external seawater environment generates a dynamic pressure gradient of up to 60 MPa.

[0044] Due to space constraints, the high-frequency transmitter module 1 has a reduced wall thickness for its housing 11. If a conventional single-mode oil medium is filled inside the housing 11, the pressure transmission rate of this single oil is lower than the rate of change of the external seawater dynamic pressure gradient, and the compressibility coefficient is fixed. This pressure hysteresis will generate a transient pressure difference between the inside and outside of the housing 11. This pressure difference acts on the thin-walled housing 11, causing inward deformation and increasing the risk of internal structural fracture and end-face seal failure.

[0045] To balance the transient pressure difference, a fluid response mechanism with active volume compensation characteristics needs to be constructed inside the launch module housing 11. When constructing this mechanism, the external seawater dynamic pressure gradient exhibits a wide range of fluctuations from atmospheric pressure to 60 MPa. The equivalent bulk elastic modulus of the single-component oil under a wide dynamic pressure gradient of 0 to 60 MPa is a fixed parameter, causing its volume contraction response rate to be lower than the rate of change of external environmental pressure, resulting in time hysteresis. This time hysteresis of the volume contraction response creates a transient pressure difference between the inside and outside of the thin-walled launch module housing. This transient pressure difference acts on the launch module housing and is converted into inward radial compression deformation, which in turn applies shear stress to the longitudinal oscillator encased within. Controlling the nonlinear compression response characteristics of the sealing fluid medium under varying pressure conditions from 0 to 60 MPa to eliminate the transient pressure difference and maintain the isostatic stress balance of the piezoelectric ceramic constitutes the constraint condition for the deep pressure-resistant and pressure-holding mechanism of the high-frequency launch module.

[0046] like Figure 2 As shown, the high-frequency transmitting module 1 is equipped with a transmitting array 12 and a pressure compensation component. The transmitting array 12 is disposed on the acoustically transparent radiating surface of the transmitting module housing 11, and includes nine independent longitudinal transducers. Each longitudinal transducer is a piezoelectric transducer that generates longitudinal vibration along the polarization direction. The longitudinal transducers are made of PZT-81 piezoelectric ceramic material, with a thickness of 2.2 mm along the polarization direction and a radiating surface dimension of 6 mm in length and 10 mm in width. The nine longitudinal transducers are arranged in a one-dimensional linear array at equal intervals along the long side of the transmitting module housing 11.

[0047] like Figure 3As shown, the pressure compensation component is located inside the transmitter module housing 11, including a buffer cavity 131 and a customized filling medium 132. The buffer cavity 131 is located inside the transmitter module housing 11 in the non-acoustic working area away from the sound-emitting radiation surface. The buffer cavity 131 is equipped with a sealed flexible fluororubber airbag, which is filled with standard atmospheric pressure air, forming a reserved volume deformation space.

[0048] During the assembly of the high-frequency transmitting module 1, a vacuum cryogenic oil filling process is used for dielectric filling. During the vacuuming and oil filling stages, a negative pressure difference is generated inside and outside the flexible fluororubber bladder, which is in a normal-pressure encapsulation state, causing it to maintain its expanded state to occupy the reserved buffer cavity 131 volume. The flexible fluororubber bladder is maintained in its initial expanded state to occupy the reserved volume using a vacuuming device. A custom-designed filling medium 132 fills the remaining space inside the transmitting module housing 11, completely covering the longitudinal oscillator. The custom-designed filling medium 132 is made of a mixture of hollow glass microspheres and modified silicone oil.

[0049] The modified silicone oil is made from low-viscosity methyl silicone oil as the base liquid. The base liquid is continuously treated in a vacuum degassing device with a vacuum degree below 100 Pa and a temperature controlled at 60°C to remove dissolved gases and free water, thus obtaining the modified silicone oil. Hollow glass microspheres are then incorporated into the modified silicone oil for mixing. The volumetric doping ratio of the hollow glass microspheres in the customized filling medium 132 ranges from 12% to 25%. During the mixing process, a vacuum stirring vessel is used to continuously stir at a preset speed under a negative pressure environment below 100 Pa, ensuring that the hollow glass microspheres are uniformly suspended in the modified silicone oil, resulting in a bubble-free customized filling medium 132.

[0050] To withstand dynamic pressure gradients of up to 60 MPa in the deep sea at depths of up to 6000 m, hollow glass microspheres are preferably high-compression-resistant, deep-sea-resistant isostatically pressure-resistant microspheres. Specifically, the isostatic compressive strength of the hollow glass microspheres needs to be greater than 60 MPa (e.g., 70 MPa or 100 MPa specifications can be selected), the average particle size is preferably distributed between 10 μm and 80 μm, and the actual density is preferably 0.3 g / cm³. 3 Up to 0.6 g / cm 3 This ensures that the microspheres do not rupture under high pressure and stably provide the required equivalent bulk modulus.

[0051] Furthermore, the low-viscosity methyl silicone oil used as the base fluid is preferably a polydimethylsiloxane fluid with a kinematic viscosity of 10 to 50 cSt (e.g., preferably 20 cSt) at 25°C. This ensures that the customized filling medium still has good fluidity and filling performance in the extreme environment of deep-sea low temperature (1°C-4°C) and extremely high water pressure, and avoids the medium from losing its pressure compensation ability due to phase change solidification caused by low temperature and high pressure.

[0052] The volumetric doping ratio of the custom-filled medium 132 follows the equivalent bulk modulus model. The equivalent bulk modulus model is used to calculate the equivalent bulk modulus of the mixed medium. The expression of the equivalent bulk modulus model is as follows: In the formula, The target equivalent bulk modulus of elasticity of the custom filling medium 132 is expressed in Pa. The intrinsic bulk modulus of hollow glass microspheres, expressed in Pa. The intrinsic bulk modulus of the modified silicone oil is expressed in Pa. The volume doping ratio of hollow glass microspheres is represented by %.

[0053] The volumetric doping ratio of hollow glass microspheres in the customized filling medium 132 was obtained by simultaneously solving a problem based on the set maximum hydrostatic pressure in the deep sea and the fixed lower limit of the volume of the buffer chamber 131. The total volumetric deformation of the customized filling medium 132 under maximum water pressure conditions was calculated using the fluid compressibility equation of state. This equation describes the volumetric change of a fluid under pressure, and its expression is: In the formula, This represents the total volumetric deformation of the customized filling medium 132 under pressure, in units of... ; This represents the total fluid volume inside the launch module housing 11, in units of ; The maximum pressure difference between the external seawater environment and the interior of the shell is taken as 60 MPa based on the parameters for a water depth of 6000 m. Given that the maximum pressure difference is 60 MPa, the total fluid volume is constant, and the total volumetric deformation does not exceed the lower limit of the fixed volume of the buffer chamber 131, the target equivalent bulk modulus of the customized filling medium 132 is derived based on the aforementioned fluid compressibility equation. Substituting the derived target equivalent bulk modulus into the equivalent bulk modulus model, the target value for the volumetric doping ratio of hollow glass microspheres in the customized filling medium 132 is calculated.

[0054] Based on the above calculation results, the three-dimensional structural dimensional constraints of the buffer cavity 131 are established. The lower limit of the fixed volume of the buffer cavity 131 is limited to the total volumetric deformation. The buffer chamber 131 is designed to accommodate the entire contraction volume of the fluid. If the fixed volume of the buffer chamber 131 exceeds the necessary limit, the volume of the initial gas remaining inside under normal pressure will increase, causing local surface collapse deformation of the launch module housing 11 due to the compressibility of the gas during the initial descent phase. Therefore, the upper limit of the fixed volume of the buffer chamber 131 is limited to the total volume deformation. 1.2 times that.

[0055] During the assembly of the high-frequency transmitting module 1, a vacuum cryogenic oil filling process is used for media filling. The sealed cavity inside the transmitting module housing 11 is evacuated to a pressure below 50 Pa using a vacuum pump. The ambient temperature is controlled between 5°C and 10°C, and the prepared custom filling medium 132 is slowly injected through a pre-drilled oil filling hole. Once the custom filling medium 132 has filled the remaining internal space and reached the set boundary of the buffer cavity 131, the oil filling hole is sealed with water.

[0056] When the unmanned underwater vehicle (UUV) dives to a depth of 6000m, the dynamic pressure gradient of the external seawater acts on the outer surface of the launch module housing 11. The customized filling medium 132, encased within the launch module housing 11, undergoes volume contraction under external pressure, based on parameters set by the equivalent bulk modulus model. This volume contraction of the customized filling medium 132 induces fluid displacement in the area of ​​the reserved buffer cavity 131.

[0057] The volume shrinkage and displacement of the customized filling medium 132 compensate for the cavity compression caused by external seawater pressure, ensuring that the hydrostatic pressure inside the launch module housing 11 rises synchronously with the dynamic gradient of the external seawater, thereby eliminating the pressure difference between the inner and outer surfaces. Through the fluid linkage compensation mechanism between the buffer cavity 131 and the customized filling medium 132, the external compressive force applied to the launch module housing 11 is converted into an elastic deformation absorption process by the internal fluid medium. The longitudinal oscillator encased within the customized filling medium 132 maintains an isostatic pressure state of force balance in the dynamic diving environment, preventing the inward deformation of the outer shell from exerting destructive shear forces on the longitudinal oscillator. The fluid linkage compensation mechanism between the buffer cavity 131 and the customized filling medium 132 eliminates internal gas interference, maintaining the structural integrity of the high-frequency launch module 1.

[0058] Example 3: In deep-sea synthetic aperture topographic mapping, the overall length boundary condition of the high-frequency receiving module 2 is set to 1100mm.

[0059] Due to the size limitations of processing equipment, it is difficult to form a 1100mm long array from a single piece of piezoelectric composite material. Therefore, a segmented manufacturing and assembly method is required to construct large-scale acoustic apertures. Structural seams are generated during the mechanical assembly of the segmented arrays. These seams cause acoustic phase discontinuity during the acoustic field sampling process, resulting in image superposition artifacts in the synthetic aperture signal output.

[0060] Furthermore, the amplitude of the 150kHz high-frequency acoustic echo signal reflected from the deep seabed is in the microvolt range. If the high-frequency acoustic echo signal is transmitted to the external conditioning circuit via a long cable across the watertight compartment, the electrical signal will experience voltage attenuation due to the parasitic capacitance of the cable along the long transmission path, and will be superimposed with the electromagnetic background noise of the deep-sea environment.

[0061] To maintain acoustic phase continuity across the long aperture and suppress echo signal transmission loss, it is necessary to introduce array equivalent compensation components and a proximity-based signal extraction arrangement. When mechanically splicing the array equivalent compensation components, structural seams exist in the mating areas of multiple short-sized piezoelectric ceramic arrays. The low acoustic impedance within these structural seams makes them acoustic blind spots and breakpoints in the sound field propagation region. Microvolt-level 150kHz high-frequency acoustic echoes experience acoustic impedance mismatch when crossing these breakpoints, leading to boundary scattering and refraction of the sound waves. This boundary scattering and refraction cause deflection of the local propagation path of the high-frequency acoustic echoes, resulting in spatial phase jumps in the induced electrical signals extracted by each receiving element of the receiving subarray. Eliminating microscopic acoustic impedance abrupt changes at the structural seams to maintain a smooth transition of the acoustic field phase across the 1100mm long-scale aperture surface, while maintaining the segmented receiving subarray in an open assembly state, constitutes a constraint on the segmented assembly process of the long-baseline high-frequency receiving array.

[0062] like Figure 3 As shown, the high-frequency receiving module 2 is equipped with a splicing receiving array and a front-end signal preprocessing circuit 23. The splicing receiving array is mounted on the acoustic receiving surface of the inner wall of the receiving module housing 21. The splicing receiving array includes two receiving subarrays 221 with the same structural dimensions. The receiving subarray 221 includes 15 receiving elements made of type 1-3 piezoelectric composite material. The type 1-3 piezoelectric composite material is a two-phase composite material formed by periodically arranging piezoelectric ceramic pillars embedded in a polymer matrix.

[0063] The center-to-center spacing between the receiving elements follows the anti-lobe acoustic constraint equation, which is used to determine the maximum permissible spacing between the array elements to avoid lobes during beam scanning. The expression for the anti-lobe acoustic constraint equation is: In the formula, This represents the maximum permissible center-to-center spacing, in meters (m). The deep-sea sound velocity parameter represents a hydrostatic pressure of 60 MPa and a low temperature of 2℃, with a value of 1530 m / s. This represents the highest upper limit frequency of the echo signal, with a value of 165kHz. The maximum beam deflection angle of the sonar system is represented in degrees. Substituting the maximum beam deflection angle parameter, the center spacing is calculated based on the anti-lobe acoustic constraint equation. The upper limit threshold. Combined with the wafer dicing allowance of the receiving element, the center-to-center spacing between the receiving elements. The configuration range is 4.6mm to 6.8mm, which limits the beam aliasing distortion of high-frequency echo signals during the spatial sampling stage.

[0064] At the mechanical joint formed by the docking of the two receiving subarrays 221, a sub-element 222 is embedded. The sub-element 222 is a passive acoustic inert placer element, made of the same type 1-3 piezoelectric composite material as the receiving subarray 221, but structurally it does not have signal lead-out electrodes of the receiving element. Since the material system is the same as the receiving element, the acoustic impedance value of the sub-element 222 at the mechanical joint matches that of the surrounding working receiving element, so that the incident sound wave will not produce abnormal scattering, diffraction or phase jump due to abrupt change in acoustic impedance when crossing the mechanical break region.

[0065] The front-end signal preprocessing circuit 23 is housed in a sealed space inside the receiver module housing 21, and is fitted to the back side of the spliced ​​receiver array. The signal output pins of the receiver subarray 221 are directly connected to the differential signal input terminal of the front-end signal preprocessing circuit 23 via microstrip lines, with the trace length limited to the millimeter range.

[0066] When performing acoustic echo reception, the spliced ​​receiving array responds to the external sound field. The sub-element 222, distributed at the mechanical seams, does not generate any signal output itself, but by occupying the seam spaces, it replaces the acoustic blind zone originally caused by the structural discontinuity with an equivalent acoustic continuous medium. Thus, the sub-element 222 compensates for the acoustic structural void caused by the mechanical seams, making the two disconnected receiving subarrays 221 equivalent to a continuous 1100mm aperture array at the external sound field perception level, maintaining a smooth transition of the sound field spatial phase. No abnormal scattering or diffraction occurs when the incident sound wave crosses the seam, thereby ensuring the accuracy of the original acoustic characteristics of the large-scale continuous aperture required for synthetic aperture signal calculation.

[0067] The receiving subarray 221 captures the acoustic wave and converts it into an initial electrical signal. This initial electrical signal is input to the front-end signal preprocessing circuit 23, which is located close to the back of the receiver array, via a microstrip line. The front-end signal preprocessing circuit 23 performs in-situ amplitude amplification and impedance transformation on the initial electrical signal. The co-package arrangement of the front-end signal preprocessing circuit 23 and the splicing receiver array ensures that the electrical signal is pre-conditioned before being output to the external long cable. This co-package arrangement avoids the effects of distributed capacitance from long-distance cables and external electromagnetic interference, reduces the transmission attenuation of high-frequency echo signals, and maintains the signal-to-noise ratio of the output electrical signal.

[0068] Example 4: In deep-sea synthetic aperture topographic mapping, the high-frequency receiving module 2 requires maintaining a weak signal extraction environment with a high signal-to-noise ratio. The front-end signal preprocessing circuit 23 continuously dissipates heat during signal processing. The splicing receiving array generates resonant aftershocks when capturing acoustic waves, and the receiving module housing 21 is subjected to mechanical waves generated by ocean currents during the unmanned underwater vehicle's navigation.

[0069] The front-end signal preprocessing circuit 23 and the splicing receiving array are co-packaged within a confined space with a cross-sectional dimension limited to 60mm wide and 50mm high. The lack of fluid convection in this confined space prevents the accumulated heat from dissipating, causing the internal ambient temperature to rise and increasing thermal noise from electronic components. The co-package arrangement also creates a solid-state dielectric bridge for mechanical wave transmission, which is directly conducted to the substrate of the front-end signal preprocessing circuit 23, leading to electromechanical interference. This continuous electromechanical interference causes depolarization of the type 1-3 piezoelectric composite material, reducing the voltage receiving sensitivity of the splicing receiving array.

[0070] To eliminate interference from high-density integration within a confined space, a structural isolation boundary with both thermal conductivity and vibration isolation properties needs to be established between the heat-generating nodes and sensitive acoustic components. When establishing this boundary, the heat conduction law overlaps with the transmission law of mechanical vibration waves in a solid medium. Constructing a low-thermal-resistance, rapid heat conduction process relies on providing a continuous and dense solid transport medium. This continuous and dense solid transport medium also constitutes a high-transmittance, linear propagation channel for low-frequency mechanical vibration waves. When the continuous solid medium is cut off to block low-frequency mechanical vibration waves, the cutting action simultaneously interrupts the directional heat conduction path of the heat-generating nodes in the front-end signal preprocessing circuit. Within a micro-assembly space limited to a width of 60 mm and a height of 50 mm, reconciling the continuous medium properties required for directional rapid heat flow conduction with the discontinuous interface properties required for non-linear mechanical wave transmission constitutes a constraint on spatial layout configuration in a narrow-domain, high-density electromechanical co-packaging environment.

[0071] like Figure 4 As shown, an isolation reinforcing rib network 24 is configured in the micro-assembly space inside the receiver module housing 21. The isolation reinforcing rib network 24 is embedded in the structural gap between the front-end signal preprocessing circuit 23 and the backing of the splicing receiver array. The isolation reinforcing rib network 24 is made of titanium alloy material with low sound wave propagation speed and high thermal conductivity. The isolation reinforcing rib network 24 is processed into a three-dimensional topological mesh shape, which is a three-dimensional mesh shape with continuous material distribution and hollow structure generated by topology optimization method.

[0072] The internal mesh arrangement of the isolation stiffener network 24 is calculated and generated based on a thermo-acoustic multi-field coupled topology optimization model. This model is used to simultaneously optimize the thermal conductivity and vibration isolation performance of the structure under given volume constraints. The objective function of the thermo-acoustic multi-field coupled topology optimization model is: In the formula, The system equivalent thermal conductivity represents the insulation and reinforcing rib network 24, in units of ; The dimensionless coefficient represents the mechanical vibration coupling coefficient transmitted from the splicing receiving array to the substrate node where the front-end signal preprocessing circuit 23 is located.

[0073] When constructing the thermo-acoustic multi-field coupled topology optimization model, a body-centered cubic lattice is selected as the initial three-dimensional structural design domain. The thermo-acoustic multi-field coupled topology optimization model uses the material volume ratio of the isolation reinforcing rib network 24 not exceeding 30% of the limited micro-assembly space as a volume constraint condition. Under the premise of satisfying the volume constraint condition, iterative solution calculation of material density distribution is performed with the optimization objective function of improving the system's equivalent thermal conductivity and reducing the mechanical vibration coupling coefficient, generating a continuous material distribution pattern of the mesh support rod. Based on the thermo-acoustic multi-field coupled topology optimization model, the isolation reinforcing rib network 24 has its first end face abutting the heat-generating heavy-load area of ​​the front-end signal preprocessing circuit 23, and its second end face abutting the metal inner wall of the receiving module housing 21.

[0074] The internal metal mesh of the insulating reinforcing rib network 24, in a direction perpendicular to the sound wave propagation path, periodically changes the cross-sectional dimensions of the mesh support rods to form a multi-frequency acoustic impedance misalignment stacked structure. The cross-sectional dimensions of the mesh support rods alternate periodically along the sound wave propagation path. The length of a single arrangement period of the mesh support rods is set according to the Bragg scattering condition of the target mechanical wave frequency. Specifically, the length of a single arrangement period is configured to be 0.4 to 0.6 times the wavelength of the target low-frequency mechanical wave propagating in the titanium alloy material. The alternating abrupt changes in the interface geometry induce a jump in the characteristic acoustic impedance of the transmission medium, causing reflection, refraction, and phase cancellation phenomena of the mechanical vibration energy.

[0075] While the front-end signal preprocessing circuit 23 processes the high-frequency echo signal and continuously dissipates heat, the isolation reinforcing rib network 24, which is in contact with the heat-generating, heavily loaded area, forms a low-thermal-resistance heat-conducting medium path. The internally accumulated heat flow is directionally conducted to the receiving module housing 21 through the metal skeleton of the isolation reinforcing rib network 24, and then dissipates through the receiving module housing 21 into the external deep-sea environment with a temperature of 1°C to 4°C. The continuous heat-conducting medium path formed by the isolation reinforcing rib network 24 suppresses the rise in internal temperature of the receiving module housing 21 and the thermal noise of electronic components.

[0076] When the unmanned underwater vehicle (UUV) triggers local water flow excitation or resonant residual vibration of the spliced ​​receiving array, low-frequency mechanical waves are transmitted to the front-end signal preprocessing circuit 23. When the mechanical waves come into contact with the isolation reinforcing rib network 24, the three-dimensional topological mesh with misaligned acoustic impedance blocks the straight transmission path of the mechanical waves. Due to the change in the cross-sectional dimensions of the mesh support rods, the internal acoustic impedance is mismatched, and the incident mechanical vibration energy undergoes diffuse reflection, refraction, and phase cancellation between the interlaced metal mesh interfaces, forcing some mechanical energy to be converted into a small amount of heat energy for dissipation.

[0077] The mechanical vibration energy undergoes continuous diffuse reflection, refraction, and phase cancellation at the interlaced metal mesh interface, causing the mechanical vibration energy of the transmitted wave to decrease exponentially. The residual vibration energy reaching the substrate of the front-end signal preprocessing circuit 23 approaches zero. The isolation reinforcing rib network 24 constructs a boundary between thermodynamic dispersion and acoustic shielding within the narrow, enclosed space of the receiving module housing 21, eliminating interference from thermal noise and electromechanical mutual interference on the operation of the high-frequency receiving module 2 and maintaining the signal-to-noise ratio during the weak signal extraction process.

[0078] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A miniaturized, integrated, and packaged deep-sea synthetic aperture sonar transducer array, characterized in that, include: A high-frequency transmitting module has a transmitting module housing, a transmitting array is arranged on the radiating surface of the transmitting module housing, and a pressure compensation component is arranged inside the transmitting module housing; the pressure compensation component is configured to undergo volume contraction and fluid displacement in response to external deep-sea dynamic transmission pressure, so as to offset the compression volume of the transmitting module housing caused by external seawater pressure, thereby dynamically balancing the transient pressure difference between the inside and outside of the transmitting module housing; A high-frequency receiving module has a receiving module housing, and the receiving module housing is provided with a splicing receiving array and a front-end signal preprocessing circuit. Mounting base, the transmitter module housing is fixed to the mounting base via transmitter mounting holes, and the receiver module housing is fixed to the mounting base via receiver mounting holes; In the assembled state, the transmitting module housing and the receiving module housing are arranged one after the other in a straight line in the horizontal direction, with the rear end face of the transmitting module housing facing the front end face of the receiving module housing, and a gap is maintained between the two facing end faces. The pressure compensation component includes a buffer cavity and a customized filling medium; the buffer cavity is located inside the housing of the transmitting module in a non-acoustic working area away from the sound-transmitting radiation surface; the customized filling medium fills the remaining space inside the housing of the transmitting module and completely covers the transmitting array, and the customized filling medium is made of a mixture of hollow glass microspheres and modified silicone oil; The volume doping ratio of the hollow glass microspheres in the customized filling medium is obtained by solving the equivalent bulk elastic modulus model; the lower limit of the fixed volume of the buffer cavity is limited to the total volume deformation of the customized filling medium under the maximum water pressure condition, and the upper limit of the fixed volume of the buffer cavity is limited to 1.2 times the total volume deformation.

2. The miniaturized integrated packaged deep-sea synthetic aperture sonar transducer array as described in claim 1, characterized in that, Damping pads are sandwiched between the connection interface between the transmitter module housing and the mounting base, and between the connection interface between the receiver module housing and the mounting base.

3. The miniaturized integrated packaged deep-sea synthetic aperture sonar transducer array as described in claim 1, characterized in that, The transmitting array includes multiple independent longitudinal oscillators, which are made of piezoelectric ceramic material and are arranged in a one-dimensional linear array at equal intervals along the long side of the transmitting module housing.

4. The miniaturized integrated packaged deep-sea synthetic aperture sonar transducer array as described in claim 1, characterized in that, The splicing receiver array is installed on the acoustic receiving surface on the inner wall of the receiver module housing. The splicing receiver array includes two receiver subarrays with the same structural dimensions. The receiver subarray includes multiple receiver elements, and the center spacing between the receiver elements is arranged according to the upper limit threshold of the anti-loudsweep acoustic constraint equation.

5. The miniaturized integrated packaged deep-sea synthetic aperture sonar transducer array as described in claim 4, characterized in that, Sub-elements are embedded at the mechanical joint formed by the docking of the two receiving subarrays. These sub-elements are made of the same piezoelectric composite material as the receiving elements and are not equipped with signal lead-out electrodes.

6. The miniaturized integrated packaged deep-sea synthetic aperture sonar transducer array as described in claim 4, characterized in that, The front-end signal preprocessing circuit is attached to the back side area of ​​the splicing receiving array; The signal output pins of the receiving subarray are directly connected to the differential signal input terminal of the front-end signal preprocessing circuit via microstrip lines.

7. The miniaturized integrated packaged deep-sea synthetic aperture sonar transducer array as described in claim 6, characterized in that, The receiver module housing is equipped with an isolation reinforcing rib network; The isolation reinforcing rib network is embedded in the structural gap between the front-end signal preprocessing circuit and the splicing receiving array backing.

8. The miniaturized integrated packaged deep-sea synthetic aperture sonar transducer array as described in claim 7, characterized in that, The isolation reinforcing rib network is made of titanium alloy and configured as a three-dimensional topological mesh. The first end face of the isolation reinforcing rib network abuts against the heat-generating heavy-load area of ​​the front-end signal preprocessing circuit, and the second end face of the isolation reinforcing rib network abuts against the metal inner wall of the receiving module housing. The internal metal mesh of the isolation reinforcing rib network has an acoustic impedance misalignment stacked arrangement in a direction perpendicular to the sound wave propagation path.

Images