Microwave wireless pressure sensor based on electromagnetic metamaterial

Abstract

The invention discloses a microwave wireless pressure sensor based on an electromagnetic metamaterial. According to the sensor, the 8x 8-unit metamaterial array is constructed, so that wireless energy collection and capture of space electromagnetic signals are realized; by constructing an electromagnetic metamaterial array cascade microwave power synthesis feed network, power synthesis and cascade transmission of wirelessly collected and captured electromagnetic signals are realized; based on the equivalent impedance response of microwave near-field resonance, a feed network output end cascade microwave complementary interdigital resonator is constructed, and electromagnetic metamaterial microwave wireless energy collection and capture characteristic regulation and control based on the resonance response of the microwave complementary interdigital resonator are realized. Based on the idea that pressure information response and pressure information generation are isolated from each other, a pressure sensing probe of a metal sensing piece, a ceramic shell and a metal pressure elastic diaphragm is constructed, and resonance characteristic pressure regulation and control of a microwave complementary interdigital resonator based on pressure strain response are achieved. And finally, the pressure information wireless sensing is realized by reading the echo characteristic information of the electromagnetic metamaterial array in real time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pressure detection sensors, in particular to a microwave wireless pressure sensor based on electromagnetic metamaterials. BACKGROUND

[0002] In the current stage of rapid social development, pressure vessels and piping systems, such as gas pipelines, steam pipelines, pressure reactors, and various gas pressure vessels, are key equipment that play an important supporting role in ensuring social material supply, improving production efficiency, and ensuring public safety. The rated working pressure of such equipment directly determines the system operation efficiency, product quality, and safety, therefore, in the process of industrial modernization, real-time and accurate sensing and monitoring of the internal pressure of pressure-bearing equipment has become a key link to ensure its stable and reliable operation. At present, pressure gauges and sensors based on mechanical transmission principles are widely used in industry. Such devices are widely used in pressure monitoring of gas pipelines, storage tanks, and steam delivery pipelines due to their flexible installation characteristics. However, such sensors rely on visual interpretation for pressure information acquisition, which not only has limited measurement accuracy, but also is difficult to adapt to the development trend of digitalization and intelligentization of industrial sensing. To overcome this limitation, capacitive pressure sensing technology has emerged, which converts mechanical deformation into capacitance change and uses electrical signals to extract and remotely transmit pressure information, significantly improving the digital level of pressure monitoring. However, this method is easily affected by the thermoelectric potential interference between the electrodes caused by temperature changes, which affects the accuracy of pressure measurement.

[0003] In recent years, with the wide application of microwave technology in radar detection, long-distance communication, medical detection and weather prediction, its advantages such as low signal power consumption, no ionizing radiation, flexible design and mature hardware technology are increasingly prominent. The good signal transmission and network compatibility of microwave measurement technology also meet the development needs of industrial detection intelligence and digitization. Based on this, microwave induction pressure sensing technology has gradually attracted attention. This kind of technology converts pressure into probe structure deformation, and then tunes its resonance characteristics (such as frequency, phase, amplitude and time delay) to realize the level conversion and acquisition of pressure signal. Typical methods include using flexible materials such as polydimethylsiloxane (PDMS) to construct a resonant cavity, and realizing the pressure-resonance response correlation through the metal structure (such as an open resonant ring) in the cavity. However, the resonant field of such sensors is easily disturbed by water vapor, oil stains, smoke or corrosive gases in the environment, and it is difficult to achieve integrated integration with industrial equipment. In order to overcome the above problems, researchers propose to use metal elastic diaphragms to realize the separation of pressure response and resonance tuning, so that the resonant unit is away from the measured environment, thereby improving the anti-interference ability and integrated adaptability. However, existing microwave pressure sensors are mostly designed based on single resonance mode, which has limited working bandwidth and low tolerance for physical preparation, resulting in degradation of sensing performance in actual wideband applications. On the other hand, electromagnetic metamaterials have been widely studied in the fields of electromagnetic stealth, electromagnetic protection and spatial electromagnetic beam control due to their flexible manipulation of electromagnetic signals such as backward transmission, inverse Doppler effect and perfect wave absorption. Although the current research on pressure sensors based on electromagnetic metamaterials is still in its infancy, its excellent electromagnetic manipulation ability provides the possibility for constructing a wireless transmission and feeding pressure sensing system.

[0004] Therefore, the microwave wireless sensing technology combined with electromagnetic metamaterials is of great significance for promoting the development of industrial pressure monitoring towards integration, intelligence and digitization. SUMMARY

[0005] The present application provides a microwave wireless pressure sensor based on electromagnetic metamaterials to solve the problems in the prior art. The technical scheme adopted by the present application is:

[0006] The application discloses a microwave wireless pressure sensor based on electromagnetic metamaterials, which adopts a waveguide interrogation antenna and an 8*8 unit metamaterial array set to realize wireless collection and transmission of space electromagnetic signals by cascading a microwave power synthesis feed network, simultaneously utilizes a pressure strain displacement of a metal pressure sensing elastic diaphragm to control a loading state of a metal sensing sheet loaded in a near area of a multi-resonance characteristic ring surface electric wall microwave complementary interdigital resonator, so that a resonant characteristic of the ring surface electric wall microwave complementary interdigital resonator responding to the pressure strain displacement is controlled. Thus, the echo characteristic of the electromagnetic metamaterials is changed due to the equivalent impedance response change of the ring surface electric wall microwave complementary interdigital resonator loaded at a load end of the cascading feed network, and finally the echo characteristic parameters of the waveguide interrogation antenna are changed. Therefore, the wireless acquisition of pressure information can be realized by reading the electromagnetic signal echo characteristic parameters of the waveguide interrogation antenna in real time. For the specific pressure sensor, a vector network analyzer firstly realizes electromagnetic signal excitation and echo signal characteristic parameter extraction of the waveguide interrogation antenna through a standard radio frequency coaxial line; in addition, the wireless electromagnetic signals emitted by the waveguide interrogation antenna are firstly collected by the electromagnetic metamaterials and then the power synthesis and transmission of the electromagnetic signals are completed through the cascading microwave power synthesis feed network; at this time, when the cascading microwave power synthesis feed network is in an impedance matching load state, the waveguide interrogation antenna has the minimum echo response result; on this basis, the echo characteristic of the electromagnetic metamaterial array is controlled by changing the impedance matching characteristic of the load at the output end of the cascading microwave power synthesis feed network, and then the echo intensity of the waveguide interrogation antenna is changed; in addition, based on the field focusing idea, a ring surface electric wall microwave complementary interdigital resonator model is proposed, and the equivalent impedance response of the ring surface electric wall microwave complementary interdigital resonator is realized by the metal sensing sheet loading tuning; on this basis, combining the pressure information response and the pressure information generation isolation idea, a metal sensing sheet pressure loading control pressure sensing probe responding to the pressure strain displacement of the metal pressure sensing elastic diaphragm is proposed, and the electromagnetic response of the pressure information strain displacement is realized; finally, the pressure strain displacement of the metal pressure sensing elastic diaphragm caused by the pressure loading controls the loading state of the metal sensing sheet, and then different equivalent impedances are generated at the output end of the cascading microwave power synthesis feed network and the echo characteristic of the electromagnetic metamaterial array is changed, and finally the echo response parameters of the waveguide interrogation antenna are changed. Therefore, the wireless sensing acquisition of the monitored environmental pressure can be realized by reading the echo characteristic parameters of the waveguide interrogation antenna.

[0007] The bolt structure integrated assembly integrated mode adopted by the sensor makes the sensor have excellent integrated embedding application integration capability of the industrial device to be measured; in addition, the metal sensing sheet loading control mode of the metal connection thin rod pressure strain displacement conduction of the three-wave high-elastic metal pressure sensing diaphragm makes the sensor also have complex embedding integration application capability.

[0008] Secondly, the pressure information response adopted by the sensor and the pressure information generation are isolated from each other, and in combination with the specific implementation of the three-wave high-elastic metal pressure sensing diaphragm, the pressure sensor of the present application has the flexible and changeable metal pressure sensing diaphragm material and structure selection customization characteristics based on specific pressure sensing monitoring requirements.

[0009] Finally, the sensor has excellent integrated characteristics and high environmental adaptability based on the microwave wireless transmission feeding mode of the waveguide interrogation antenna, electromagnetic metamaterial and cascaded microwave power synthesis feeding network. At the same time, the microwave wireless transmission feeding mode makes the pressure sensor and its sensing system have flexible assembly and disassembly characteristics, which gives it excellent intelligent and digital industrial device pressure sensing application potential in the future.

[0010] The beneficial effects of the present application are:

[0011] (1) The present application realizes the wireless energy collection and transmission of spatial electromagnetic signals by constructing a waveguide interrogation antenna, an electromagnetic metamaterial array and a cascaded microwave power synthesis feeding network model, and realizes the sensing feeding application of wireless energy collection and transmission of spatial electromagnetic signals;

[0012] (2) The present application realizes the equivalent impedance response of the target operating frequency under the near-field multi-resonance characteristics of the microwave complementary interdigital resonator by constructing a toroidal electric wall microwave complementary interdigital resonator, realizes the impedance adjustment sensing application of the near-field resonance response;

[0013] (3) The present application realizes the isolation of the pressure information response and the pressure information generation by constructing a strain displacement conversion response pressure sensing probe of the pressure information of the three-wave high-elastic metal pressure sensing diaphragm, and realizes the strain displacement conversion characterization and sensing application of the pressure information;

[0014] (4) The pressure sensing probe of the three-wave high-elastic metal pressure sensing diaphragm and the ceramic shell has flexible and changeable structure and material selection according to the actual pressure measuring environment, so that it has the potential for long-time and high-reliability pressure sensing application under complex working conditions;

[0015] (5) The microwave wireless pressure sensor based on electromagnetic metamaterial constructed by the present application has the characteristics of simple and compact overall structure, convenient disassembly, strong environmental adaptability, easy integration with the to-be-measured industrial device, and has the potential to meet the intelligent and digital pressure sensing monitoring application requirements of future work equipment. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The present application is a microwave wireless pressure sensor structure based on electromagnetic metamaterial and a pressure sensing system composition schematic diagram.

[0017] Figure 2This is a schematic diagram of the 8*8 unit electromagnetic metamaterial array and cascaded microwave power combining feed network structure in this invention.

[0018] Figure 3 This is a schematic diagram showing the electromagnetic signal reflection results and electromagnetic signal collection and capture efficiency results of the electromagnetic metamaterial in this invention.

[0019] Figure 4 This is a schematic diagram of the rectangular waveguide interrogation antenna structure in this invention and a schematic diagram of the reflection coefficient results of the electromagnetic signal of the waveguide interrogation antenna in the frequency range of 4.0 GHz to 8.0 GHz.

[0020] Figure 5 This is a schematic diagram showing the results of wireless collection, capture, and transmission of electromagnetic signals from an electromagnetic metamaterial array and a cascaded microwave power combining feed network in the frequency range of 4.0 GHz to 8.0 GHz under impedance matching load at the output end of the feed network, at different waveguide interrogation antenna loading distances.

[0021] Figure 6 This is a schematic diagram showing the electromagnetic signal reflection results of the waveguide interrogation antenna at different loading distances under the equivalent impedance load range of 50Ω to 500Ω at the output end of the electromagnetic metamaterial array and cascaded microwave power combining feed network structure of the present invention.

[0022] Figure 7 This is a schematic diagram of the toroidal electrically walled microwave complementary interdigital resonator structure in this invention.

[0023] Figure 8 This is a schematic diagram of the electromagnetic signal reflection results of the toroidal electric wall microwave complementary interdigital resonator in the present invention in the frequency range of 4.0 GHz to 12.0 GHz under no-load conditions.

[0024] Figure 9 This is a schematic diagram of the integrated toroidal electric wall microwave complementary interdigital resonator, metal induction plate, ceramic housing, ceramic flange, metal conductive connecting rod, and metal pressure sensing elastic diaphragm pressure electromagnetic response probe structure of the present invention.

[0025] Figure 10 The diagram shows the reflection results of the electromagnetic signal of the integrated pressure electromagnetic response probe in this invention under different metal induction plate loading conditions in the frequency range of 4GHz to 12GHz and the equivalent impedance response results at a frequency of 6.5GHz.

[0026] Figure 11 This is a schematic diagram showing the structural strain-displacement response of the three-corrugated high-elasticity metal pressure-sensing diaphragm in this invention under different diaphragm thicknesses and pressure loading.

[0027] Figure 12This is a schematic diagram of the experimental test results of the microwave wireless pressure sensor based on electromagnetic metamaterials according to the present invention.

[0028] In the diagram: 1-Vector network analyzer, 2-Standard RF coaxial cable, 3-Rectangular waveguide interrogation antenna, 4-Electromagnetic metamaterial array, 5-Microwave power combining feed network, 6-Standard SMA coaxial probe feed structure, 7-Integrated fixing bolt, 8-Toroidal electric wall microwave complementary interdigital resonator, 9-Rectangular ceramic housing, 10-Metal induction plate, 11-Pressure strain displacement conduction connecting metal rod, 12-Triple corrugated high elastic metal pressure sensing diaphragm, 13-T-type ceramic thermal strain conduction connecting column, 14-Ceramic flange assembly connection module, 13-Integrated application integrated assembly ceramic flange assembly connector through-hole structure. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1 As shown, the microwave wireless pressure sensor based on electromagnetic metamaterials proposed in this invention includes a vector network analyzer 1, a coaxial line 2 for microwave signal transmission, and a rectangular waveguide interrogation antenna 3 for wireless transmission and reception of spatial electromagnetic signals; an 8*8 unit metamaterial array (4) for collecting and capturing spatial electromagnetic signals; a microwave power synthesis transmission feed network (5) for collecting and transmitting electromagnetic signals from the electromagnetic metamaterial array; a microwave complementary interdigital resonator (8) fed by a standard coaxial SMA structure (6) and assembled using a bolt structure (7); a ceramic housing (9) for assembling and integrating with the microwave complementary interdigital resonator; a metal induction plate (10) for loading and controlling the near-field resonance response of the microwave complementary interdigital resonator; a thin metal rod (11) for transmitting strain displacement under pressure loading; a three-corrugated high-elasticity metal pressure sensing diaphragm (12) for converting pressure information into strain displacement; and a ceramic flange and bolt mounting holes (13) for integrated assembly of the microwave complementary interdigital resonator based on a bolt structure.

[0031] like Figure 2As shown, the electromagnetic metamaterial array of the microwave wireless pressure sensor based on electromagnetic metamaterials proposed in this invention is an 8*8 element array. The top layer of the metamaterial element is an open resonant ring with an outer radius r = 3.30 mm, a ring patch width w = 1.70 mm, a ring opening gap width g = 1.20 mm, a metamaterial element period length p = 8.50 mm, and a metamaterial substrate thickness t1 = 2.00 mm. At the bottom of the metamaterial substrate is a metal ground plane. On the back side of the metamaterial array is a cascaded microwave power combining feed network connected to the metamaterial array via metal pillars, where the feed network substrate thickness is t2 = 1.00 mm. Both the metamaterial array and the cascaded microwave power combining feed network substrates are ceramic substrates (relative permittivity εr = 9.21, loss tangent tanδ = 0.0004). The optimized thirteen-level impedance variation microstrip stub dimensions of the microwave power combining feed network, guided by a proposed electromagnetic metamaterial element metal pillar and grounding load impedance of 40 Ω, are shown in Table 1. The interface connecting the metamaterial unit to the metal pillar is the input of the feed network, with the corresponding impedance matching transformation stub having length and width of l1 and w1, respectively. At the coaxial output of the feed network is the thirteenth-stage impedance matching transformation stub, with corresponding microstrip line lengths and widths of l13 and w13.

[0032] Table 1 Impedance transformation stub structure parameters of the electromagnetic metamaterial cascaded microwave power combining feed network

[0033]

[0034] like Figure 3 As shown, the electromagnetic metamaterial unit of the microwave wireless pressure sensor based on electromagnetic metamaterials proposed in this invention exhibits electromagnetic signal reflection and collection / capture results under the following structural parameters: resonant ring outer radius r = 3.30 mm, ring patch width w = 1.70 mm, ring opening gap width g = 1.20 mm, metamaterial unit period length p = 8.50 mm, metamaterial substrate thickness t1 = 2.00 mm, and metal pillar grounding impedance of 40 Ω. The metamaterial model achieves an electromagnetic signal collection / capture efficiency exceeding 99% at a central operating frequency of 6.5 GHz, while maintaining a reflection coefficient of less than -25 dB. Simultaneously, the frequency bandwidth for electromagnetic signal collection / capture exceeding 90% is Δf1 = 0.764 GHz, and the frequency bandwidth for electromagnetic signal collection / capture exceeding 80% is Δf2 = 1.152 GHz. Based on this electromagnetic metamaterial model, efficient collection / capture of spatial electromagnetic signals at a target frequency of 6.5 GHz can be achieved.

[0035] like Figure 4The diagram shows the structural parameters of the rectangular waveguide interrogation antenna for a microwave wireless pressure sensor based on electromagnetic metamaterials proposed in this invention: la1 = 57.75 mm, la2 = 7.77 mm, la3 = 29.30 mm, ha1 = 11.00 mm, ha2 = 8.70 mm, hf = 33.00 mm, and lw = 0.45 mm, along with a schematic diagram of its electromagnetic signal reflection results. Under these structural parameters, the rectangular waveguide interrogation antenna achieves a reflection coefficient S11 < -50 dB at the target operating frequency of 6.5 GHz.

[0036] like Figure 5 As shown, this invention presents the results of microwave wireless signal collection, capture, and transmission at different loading distances for a rectangular waveguide interrogation antenna when an impedance-matched load is applied to the output end of the proposed electromagnetic metamaterial-based microwave wireless pressure sensor and its 8*8 electromagnetic metamaterial array coupled with a cascaded microwave power combining feed network. The results show that when the waveguide interrogation antenna and the electromagnetic metamaterial array are at a loading distance of 60 mm, an electromagnetic signal wireless collection, capture, and transmission efficiency exceeding 25% can be achieved. Even when the waveguide interrogation antenna and the electromagnetic metamaterial array are at a loading distance of 160 mm, an electromagnetic signal wireless collection, capture, and transmission efficiency exceeding 12% can still be achieved.

[0037] Figure 6 The figure shows the reflection results of the waveguide interrogation antenna under different output end load impedances of the cascaded microwave power combining feed network at different waveguide interrogation antenna wireless loading distances proposed in this invention. The results show that when the waveguide interrogation antenna loading distance is fixed, the spatial electromagnetic signal reflection intensity of the electromagnetic metamaterial array and the cascaded microwave power combining feed network increases with the increase of the load impedance at the load end of the feed network, thereby increasing the electromagnetic signal reflection intensity of the waveguide interrogation antenna. These results indicate that once pressure control of the load end impedance characteristics of the microwave power combining feed network is achieved, pressure information can be obtained based on the wireless echo characteristic parameters of the waveguide interrogation antenna.

[0038] Figure 7The diagram shows a schematic of the toroidal electric-walled microwave complementary interdigital resonator structure for a microwave wireless pressure sensor based on electromagnetic metamaterials proposed in this invention. The resonant structure of the toroidal electric-walled microwave complementary interdigital resonator consists of eight resonant fingers with specific parameters: r = 4.105 mm, l1 = 2.125 mm, l2 = 7.035 mm, l3 = 6.325 mm, l4 = 3.275 mm, w1 = 0.50 mm, w2 = 0.65 mm, g1 = 0.30 mm, g2 = 0.45 mm, and h = 3.00 mm. The middle layer of the toroidal electric-walled microwave complementary interdigital resonator is an FR-4 substrate (relative permittivity εr = 4.3, loss tangent tanδ = 0.0025). The resonator substrate is surrounded by thin metal plates to form a toroidal electric wall, thereby achieving near-field focusing enhancement of the resonant field. The bottom layer of the resonator is a metal ground plane; at the center of the metal ground plane and the FR-4 substrate, a through-hole structure combined with an SMA probe structure 4 is used to achieve coaxial back-feed power supply; the resonator is assembled and integrated using a bolt structure 6.

[0039] Figure 8 The diagram shows the electromagnetic signal reflection results of the toroidal electric wall microwave complementary interdigital resonator of the microwave wireless pressure sensor based on electromagnetic metamaterials proposed in this invention under no-load conditions, with structural parameters r = 4.105 mm, l1 = 2.125 mm, l2 = 7.035 mm, l3 = 6.325 mm, l4 = 3.275 mm, w1 = 0.50 mm, w2 = 0.65 mm, g1 = 0.30 mm, g2 = 0.45 mm, and h = 3.00 mm. The results show that the toroidal electric wall microwave complementary interdigital resonator generates significant electromagnetic resonances at frequencies of 5.713 GHz, 8.04 GHz, and 10.66 GHz within the 4 GHz to 12 GHz range. At these relevant frequencies, the reflection coefficients are S11 = -6.59 dB, S11 = -7.31 dB, and S11 = -20.39 dB, respectively. The results show that the toroidal electric wall microwave complementary interdigital resonator of this invention has rich multi-resonance response characteristics.

[0040] like Figure 9The image shows an integrated pressure sensing probe based on electromagnetic metamaterials and a microwave wireless pressure sensor, as proposed in this invention. The pressure sensing probe comprises a standard coaxial SMA structure, an integrated assembly bolt structure, a toroidal electric wall microwave complementary interdigital resonator, an integrated ceramic housing, a metal sensing element, a pressure strain transmission metal rod, a three-corrugated highly elastic metal pressure sensing diaphragm for converting pressure information into strain-displacement response, and a ceramic flange with bolt holes for the integrated assembly of the microwave complementary interdigital resonator based on the bolt structure. During operation, pressure loading causes the three-corrugated highly elastic metal pressure sensing diaphragm to generate a unidirectional pressure strain-displacement response, realizing the strain-displacement conversion of pressure information. The strain-displacement response of the three-corrugated highly elastic metal pressure sensing diaphragm is transmitted through the metal connecting rod, achieving pressure regulation of the metal sensing element's loading state, further altering the resonance characteristics of the toroidal electric wall microwave complementary interdigital resonator, and ultimately realizing the electromagnetic response characterization of pressure information.

[0041] like Figure 10 The figure shows the resonant response of the integrated pressure sensing probe of the microwave wireless pressure sensor based on electromagnetic metamaterials proposed in this invention, within the loading range of the metal inductor plate (dis = 0.1 mm to dis = 2.5 mm). The results show that the integrated pressure sensing probe exhibits significant resonant offset response characteristics within the loading range of the metal inductor plate 8 (dis = 0.1 mm to dis = 2.5 mm). Furthermore, this resonant response achieves monotonic equivalent impedance changes of 69.21 Ω and 2774.38 Ω at the target operating frequency of 6.5 GHz, respectively. This confirms that the toroidal electric wall microwave complementary interdigital resonator 5 of this invention can achieve a monotonic equivalent impedance response at the target operating frequency of 6.5 GHz by adjusting the loading state of the metal inductor plate 8.

[0042] like Figure 11 As shown, the three-corrugated high-elasticity metal pressure-sensing diaphragm proposed in this invention is based on stainless steel material (Poisson's ratio v = 0.31, Young's modulus E = 1.93 × 10⁻⁶). 5The diagram illustrates the pressure strain displacement response of the proposed three-corrugated high-elasticity metal pressure-sensing diaphragm under a maximum pressure loading of 5 MPa, with a thickness range of tp = 0.08 mm to tp = 0.15 mm, a corrugated ring spacing of tw = 0.75 mm, a corrugated ring width of tg = 0.35 mm, and a working surface diameter of tl = 10.00. The results show that, under the same pressure excitation, the strain displacement of the proposed three-corrugated high-elasticity metal pressure-sensing diaphragm varies with the diaphragm thickness. Specifically, when the thickness of the metal pressure-sensing diaphragm is tp = 0.08 mm, the strain displacement response reaches 260 μm under a pressure loading of 1 MPa. When the loading pressure reaches the simulated maximum of 5 MPa, the strain displacement response exceeds 650 μm. These results demonstrate the significant pressure strain displacement response of the metal pressure-sensing diaphragm. It is foreseeable that, through analysis and experimental testing, selecting a three-wave temperature metal pressure sensing diaphragm based on the target pressure sensing range will enable the monitoring of strain conversion response of pressure information.

[0043] like Figure 12 The figure shows the experimental test results of the microwave wireless pressure sensor based on electromagnetic metamaterials proposed in this invention within a maximum pressure range of 1 MPa. The experimental results show that the microwave wireless pressure sensor based on electromagnetic metamaterials has an average pressure resolution of 4.9812 dB / MPa when the waveguide interrogation antenna loading distance is 100 mm, and the test result deviation is less than 0.1450 dB. The experimental test results confirm the feasibility of this invention.

[0044] In summary, this invention proposes using electromagnetic metamaterials combined with a cascaded microwave power synthesis feed network to achieve the collection, capture, and transmission of spatial electromagnetic signals. It also utilizes the fundamental physical phenomenon of metal pressure strain displacement response to achieve multi-resonance equivalent impedance response modulation of a toroidal electric wall microwave complementary interdigital resonator. Furthermore, based on the idea of ​​isolating the pressure information sensing area and the pressure information generation area of ​​the pressure sensing probe, the proposed microwave wireless pressure sensor not only possesses excellent wireless integrated sensing capabilities but also pressure sensing capabilities dependent solely on the pressure strain response limit of the three-corrugated high-elasticity metal pressure sensing diaphragm itself. It is foreseeable that in specific industrial applications, by employing more mature and precise fabrication processes and materials with better electrical properties, combined with anti-oxidation and anti-corrosion coating processes for the physical fabrication of the wireless feed transmission system, the proposed microwave wireless pressure sensing technology based on electromagnetic metamaterials and a toroidal electric wall microwave complementary interdigital resonator will possess even superior wireless feed sensing performance. This will provide new sensing principles and technical approaches for the monitoring of industrial devices with complex operating conditions and their integrated applications.

Claims

1. A microwave wireless pressure sensor based on electromagnetic metamaterials, the sensing features including a vector network analyzer (1) and a coaxial signal transmission line (2) for realizing the excitation and response of microwave sensing signals and a rectangular waveguide interrogation antenna (3); an 8*8 unit metamaterial array (4) for realizing the collection and capture of spatial electromagnetic signals and a cascaded microwave power synthesis transmission feed network (5); a microwave complementary interdigital resonator (8) fed by a standard coaxial SMA structure (6) and assembled using a bolt structure (7); a non-metallic ceramic housing (9) for assembling and integrating with the microwave complementary interdigital resonator; a metal induction plate (10) for realizing the near-field resonance response modulation of the microwave complementary interdigital resonator; a metal rod (11) for realizing the transmission of strain displacement under pressure loading; a metal pressure-sensing elastic diaphragm (12) for realizing the conversion of strain displacement response of pressure information; and a ceramic flange (13) for realizing the integrated assembly and integrated application assembly of the sensor based on a bolt structure.

2. A microwave wireless pressure sensor based on electromagnetic metamaterials according to claim 1, wherein the electromagnetic metamaterial array is characterized by being composed of 8*8 metamaterial units to collect and capture microwave wireless signals emitted by a rectangular waveguide interrogation antenna (3); the electromagnetic metamaterial array (4) unit is cascaded with the input end of the bottom microwave power combining feed network (5) using metal pillars to realize the power combining and transmission feed of the microwave power flow collected and captured by the electromagnetic metamaterial array; the microwave power combining feed network uses a coaxial output structure (6) as the output end to realize the wireless transmission feed of the microwave complementary interdigital resonator (8) cascaded at the output end of the power combining feed network.

3. According to claim 1, the microwave wireless pressure sensor based on electromagnetic metamaterials, wherein the top layer of the microwave complementary interdigital resonator (8) is a complementary interdigital structure composed of eight core resonant phalanges; the substrate of the microwave complementary interdigital resonator is a non-metallic substrate FR-4, and a toroidal electric wall is constructed around the FR-4 substrate using metal sheets, and the bottom of the substrate is a metal ground plane; the microwave complementary interdigital resonator (8) adopts a coaxial center probe structure for microwave coaxial feeding (6); the microwave complementary interdigital resonator (8) adopts a bolt structure (7) to achieve integrated assembly with the sensor.

4. A microwave wireless pressure sensor based on electromagnetic metamaterials according to claim 1, wherein the pressure sensor uses a metal pressure-sensing elastic diaphragm (12) to realize the strain-displacement conversion response of pressure information, and the strain displacement is transmitted through a metal connecting rod (11) to realize the pressure strain loading control of the metal sensing sheet (10), and finally realizes the pressure control of the resonance characteristics of the microwave complementary interdigital resonator (10).

5. According to claim 4, a microwave wireless pressure sensor based on electromagnetic metamaterials, the pressure sensing probe can be flexibly selected and customized in terms of material and structure of flexible metal pressure sensing elastic diaphragm (12) according to pressure measurement requirements, so as to realize the isolation between pressure information response and pressure information generation; the sensor adopts a rectangular ceramic shell (9) and a ceramic flange structure (11) and combines them with assembly bolts (7) and ceramic flange fixing through holes (13) to realize the integrated assembly of the sensor and the integrated assembly of the application.

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