A self-powered wireless sensing and communication device based on radio frequency energy capture

Abstract

The present invention discloses a self-powered wireless sensing and communication device based on radio frequency energy capture. The device realizes the functions of capturing radio frequency energy and sensors through a double-layer microstrip patch antenna, and realizes the functions of capturing radio frequency energy and wireless communication through a dual-frequency microstrip patch antenna. The upper antenna of the double-layer microstrip patch antenna forms the top surface of the shell. The four sides of the shell are formed by the dual-frequency microstrip patch antenna and are fixedly connected to the four sides of the upper antenna. The antenna support frame forms the bottom surface of the shell and can be slidably limited within the shell. The transition circuit is used to integrate the captured radio frequency energy into the radio frequency rectification circuit. The radio frequency rectification circuit is used to convert the radio frequency energy into direct current. The energy storage device is used to store electrical energy and supply the electrical energy to the control module. The above device can efficiently and omnidirectionally capture radio frequency energy, monitor changes in physical quantities in the environment, and realize the integrated integration of radio frequency energy capture and wireless communication.

Description

Technical Field

[0001] The present invention belongs to the technical field of Internet of Things, and in particular relates to a self-powered wireless sensing and communication device based on radio frequency energy capture. Background Art

[0002] With the continuous development of the Internet of Things (IoT), the demand for wireless sensor networks (WSNs) in smart homes, smart factories, smart transportation, and other fields is growing. While IoT devices are widely used, they also face significant challenges in energy supply. Traditional wireless sensors typically rely on batteries, which not only increases maintenance costs but also limits the long-term use and environmental sustainability of the devices. Therefore, the development of self-powered wireless smart sensing devices has become a research hotspot, and radio frequency (RF) energy harvesting technology is an ideal solution.

[0003] RF energy harvesting technology captures ambient RF energy (such as Wi-Fi, Bluetooth, and mobile communication signals) and converts it into direct current (DC) to power low-power devices. However, existing RF energy harvesting devices often rely on a single functional module, resulting in the separation of energy harvesting from sensing and communication functions.

[0004] In terms of sensing technology, patch antennas themselves can serve as highly integrated and miniaturized sensors, with promising applications in the Internet of Things. Patch antennas not only effectively capture radio frequency signals but also serve as sensors to monitor environmental changes. Specifically, they can detect variations in temperature, humidity, gas concentration, vibration displacement, stress, and strain through changes in the antenna's resonant frequency. Because the resonant frequency of patch antennas is highly sensitive to environmental changes, they offer unique advantages in wireless sensing.

[0005] However, current research on combining RF energy capture and sensing functions within a single antenna system is still in-depth. In particular, achieving multifunctional integration of patch antennas to simultaneously perform energy capture, environmental perception, and information communication remains a technical challenge. Most existing technologies focus on RF energy capture or a single sensing function, particularly in the unified design of physical structures and functional modules, and have yet to achieve high levels of integration and high performance. Summary of the Invention

[0006] The present invention provides a self-powered wireless sensing and communication device based on radio frequency energy capture. The self-powered wireless sensing and communication device can efficiently and omnidirectionally capture radio frequency energy through a dual-frequency microstrip patch antenna and a double-layer microstrip patch antenna, monitor changes in physical quantities in the environment, and realize the integrated integration of radio frequency energy capture and wireless communication through time division multiplexing.

[0007] In order to achieve the above object, the present invention adopts the following specific technical solutions:

[0008] A self-powered wireless sensing and communication device based on radio frequency energy capture, comprising a housing, a dual-band microstrip patch antenna, a double-layer microstrip patch antenna, an antenna support frame, a transition circuit, a radio frequency switch, a radio frequency rectifier circuit, an energy storage device, and a control module;

[0009] The shell is a hollow cubic structure; the double-layer microstrip patch antenna includes an upper antenna and a lower antenna that are completely separated and have an air gap, and are used to achieve the functions of capturing radio frequency energy and sensors; the upper antenna forms the top surface of the shell; the lower antenna is supported on the bottom end of the upper antenna by the antenna support frame; the four side surfaces of the shell are formed by the dual-band microstrip patch antenna and are fixedly connected to the four sides of the upper antenna; the antenna support frame forms the bottom surface of the shell and can be slidably limited in the vertical direction between the four side surfaces of the shell to change the height of the air gap; the dual-band microstrip patch antenna is used to achieve the functions of capturing radio frequency energy and wireless communication; the lower antenna and the dual-band microstrip patch antenna are both coaxially fed by backfeeding and are connected to the radio frequency rectifier circuit;

[0010] The transition circuit, the RF switch, the RF rectification circuit, the energy storage device and the control module are all located in the shell and fixedly mounted on the antenna support frame; the transition circuit is used to integrate the RF energy captured by the double-layer microstrip patch antenna and the dual-frequency microstrip patch antenna into the RF rectification circuit; the RF rectification circuit is used to convert the RF energy into direct current; the energy storage device is used to store the electric energy converted by the RF rectification circuit and supply the electric energy to the control module to realize self-powered operation; the control module controls the RF switch to realize function switching of the dual-frequency microstrip patch antenna, and realizes RF energy capture and wireless communication in different time periods.

[0011] Furthermore, the dual-band microstrip patch antenna includes a radiating patch, a first dielectric substrate, a first metal ground layer, and a first coaxial probe feeding structure; the radiating patch is formed on the outer side of the first dielectric substrate; the first metal ground layer is formed on the inner side of the first dielectric substrate; the first coaxial probe feeding structure is composed of an SMA adapter welded to the radiating patch, the first metal ground layer, and the first coaxial feeding through-hole of the first dielectric substrate, which is used to achieve resonance in different frequency bands, so that the dual-band microstrip patch antenna operates in dual frequency bands.

[0012] Furthermore, the radiation patch and the first metal ground layer are formed on the first dielectric substrate by depositing metal copper; the radiation patch is subjected to anti-oxidation treatment by tin plating; the inner surface of the first metal ground layer is provided with a solder resist layer for increasing isolation; the radiation patch and the first metal ground layer are both rectangular, and the length and width of the radiation patch are both smaller than the first dielectric substrate; the first metal ground layer covers the inner side surface of the first dielectric substrate; and the first dielectric substrate is made of a high-strength insulating material.

[0013] Furthermore, the upper antenna is a parasitic patch antenna; the lower antenna is a main patch antenna;

[0014] The parasitic patch antenna is fed by electromagnetic coupling.

[0015] Furthermore, the parasitic patch antenna includes a second dielectric substrate and a parasitic patch formed on a top surface of the second dielectric substrate;

[0016] The parasitic patch serves as a parasitic coupling unit, increases the bandwidth of the antenna through electromagnetic coupling, and improves the overall radiation efficiency of the antenna; the shape of the parasitic patch is rectangular or circular.

[0017] Furthermore, the main patch antenna includes a main radiation patch, a third dielectric substrate, a second metal ground layer and a second coaxial probe feeding structure;

[0018] The main radiation patch is formed on the top surface of the third dielectric substrate;

[0019] The second metal grounding layer is formed on the bottom surface of the third dielectric substrate;

[0020] The second coaxial probe feeding structure is fixedly mounted on the main radiation patch, the third dielectric substrate and the second metal ground layer;

[0021] When the main patch antenna is electromagnetically excited, the induced electromagnetic field will excite surface currents and generate resonance.

[0022] Furthermore, when the double-layer microstrip patch antenna is used as a sensor, changes in physical quantities in the environment cause changes in the height of the air gap, which causes changes in the antenna resonant frequency, resulting in changes in the efficiency of the radio frequency rectifier circuit, thereby realizing monitoring of physical quantities in the environment.

[0023] Furthermore, the antenna support frame consists of a base plate and four support columns, and is made of a low dielectric constant, smooth and insulating material; the base plate forms the bottom surface of the shell and can be slidably located between the four dual-band microstrip patch antennas in the vertical direction; the bottom end of the support column is fixedly mounted on the top surface of the base plate, and the top end is supported on the bottom surface of the lower antenna.

[0024] Furthermore, the transition circuit is a 4:1 type power divider connected by equal-length coaxial lines, having four first input ports and one first output port, each first input port is connected to one of the dual-band microstrip patch antennas, and the first output port is connected to the radio frequency switch;

[0025] The RF switch has one second input port and two second output ports; the second input port is connected to the output end of the transition circuit, one second output port is connected to the RF rectifier circuit, and the other second output port is connected to the control module.

[0026] Furthermore, the radio frequency rectification circuit includes an impedance matching circuit and a voltage doubling rectification circuit;

[0027] The energy storage device is a supercapacitor;

[0028] The control module samples the DC output voltage of the radio frequency rectifier circuit, calculates the rectification efficiency, and transmits the information to the dual-band microstrip patch antenna through data encoding;

[0029] The control module controls the radio frequency switch in a time-division multiplexing manner to achieve switching between radio frequency energy capture and wireless communication functions.

[0030] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0031] 1. The self-powered wireless sensing and communication device of the present invention is based on RF energy capture technology. Antennas are arranged in the X, Y, and Z directions respectively, so that omnidirectional capture of RF energy of different frequency bands widely existing in free space can be achieved, thereby improving the capture efficiency and availability of RF energy, providing power support for the control module and antenna, reducing the maintenance cost of wireless sensor nodes and the need for battery replacement, thereby realizing self-powered operation of the sensor nodes.

[0032] 2. The double-layer microstrip patch antenna on the top of the housing extends the bandwidth and improves antenna gain compared to traditional microstrip patch antennas. This double-layer microstrip patch antenna consists of two layers: the upper layer is a parasitic patch antenna, and the lower layer is a main patch antenna. Placing the parasitic patch antenna above the main patch antenna, electromagnetic field coupling induces currents in the parasitic patch, forming a new resonant mode. This is equivalent to connecting multiple resonant loops in parallel in the antenna's equivalent circuit model, thereby extending the antenna's operating bandwidth. The presence of the parasitic patch increases the radiating surface area, enlarging the antenna's equivalent aperture and improving gain. Furthermore, the presence of the air gap effectively reduces dielectric loss, improves radiation efficiency, and thus increases antenna gain. The parasitic patch coupling design reduces physical connections, allows for flexible adjustment of the air gap height, and avoids the problems of poor contact and wear that can occur with traditional coaxial feeding methods. Therefore, the double-layer microstrip patch antenna design enhances RF energy capture within the corresponding frequency band.

[0033] 3. The dual-layer microstrip patch antenna on top of the housing not only captures RF energy but also functions as a sensor. When the entire device is placed on the monitored object, changes in environmental physical quantities (such as pressure, stress, strain, and vibration displacement) are transmitted to the device's bottom (i.e., the baseplate of the antenna support frame). This causes the air gap between the dual-layer microstrip patch antennas to change in height, resulting in changes in the antenna's resonant frequency, which in turn affects the rectification efficiency of the entire device. By recording and monitoring changes in rectification efficiency, changes in the corresponding physical quantity can be inferred without the need for an additional independent sensor, reducing device size and achieving highly integrated sensing capabilities.

[0034] 4. The four dual-band microstrip patch antennas arranged on the side of the shell can simultaneously achieve RF energy capture and wireless communication. By finding a suitable feeding point on a single-layer patch, the antenna can operate in two frequency ranges, improving the efficiency of RF energy capture. At the same time, the RF switch is controlled in a time-division multiplexing manner, allowing the dual-band microstrip patch antenna to operate in RF energy capture and wireless communication modes respectively. The four dual-band microstrip patch antennas arranged orthogonally in the X and Y directions provide good omnidirectional coverage, reduce dependence on the incident direction, and improve the stability of RF energy capture and wireless communication. This design enhances the versatility and system integration of the device, simplifies the circuit structure, reduces system complexity, and realizes self-powered operation of the wireless sensor node.

[0035] 5. The present invention combines RF energy capture, wireless sensing and communication technologies to achieve self-powered operation of wireless sensor nodes in the Internet of Things environment. The realization of the antenna sensing function does not rely on the expensive vector network analyzer in traditional technology, but combines RF energy capture technology to monitor the rectification efficiency of the rectifier circuit, thereby realizing the monitoring and sensing of physical quantities in the environment, greatly reducing the cost and complexity of the sensing system. In addition, the device adopts a time-sharing multiplexing control method, which can switch between RF energy capture and wireless communication, and flexibly allocate energy flow through RF switches and power dividers to achieve efficient energy management and communication functions. The invention does not require external power supply and has the advantages of miniaturization, low power consumption, long life, and high integration. It is particularly suitable for Internet of Things fields such as smart homes and smart factories, and provides an integrated solution for self-powered wireless sensing and communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the external overall structure of the self-powered wireless sensing and communication device of the present invention.

[0037] Figure 2 This is a schematic diagram of the exploded structure of the self-powered wireless sensing and communication device of the present invention.

[0038] Figure 3 Schematic diagram of the exploded structure of the dual-band microstrip patch antenna.

[0039] Figure 4 Schematic diagram of the exploded structure of the double-layer microstrip patch antenna.

[0040] Figure 5 Schematic diagram of the assembly structure of the antenna support frame and the double-layer microstrip patch antenna.

[0041] Figure 6 This is a block diagram of the working principle of the self-powered wireless sensing and communication device of the present invention.

[0042] Figure numerals: 1-first dielectric substrate, 2-radiation patch, 3-first coaxial feed via, 4-parasitic patch, 5-second dielectric substrate, 6-main radiation patch, 7-third dielectric substrate, 8-second metal ground layer, 9-second coaxial feed via, 10-support column, 11-bottom plate, 12-transition circuit, 13-RF switch, 14-RF rectifier circuit, 15-control module, 16-energy storage device, 17-SMA adapter, 18-first metal ground layer. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] like Figure 1 、 Figure 2 and Figure 6 As shown, this embodiment provides a self-powered wireless sensing and communication device based on RF energy capture, which includes a housing, a dual-band microstrip patch antenna, a double-layer microstrip patch antenna, an antenna support frame, a transition circuit 12, an RF switch 13, an RF rectifier circuit 14, an energy storage device 16, and a control module 15; wherein:

[0045] The shell is a hollow cubic structure. The shell is not only used to support and protect the internal electronic components, but also serves as the dielectric substrate of the antenna. The specific size is optimized according to application requirements; the transition circuit 12, the RF switch 13, the RF rectifier circuit 14, the energy storage device 16 and the control module 15 are all installed in the shell; the shell can be composed of a double-layer microstrip patch antenna constituting the top surface, a dual-frequency microstrip patch antenna constituting the four sides and an antenna support frame constituting the bottom surface, or it can be composed of a cubic frame; when a cubic frame is used, the double-layer microstrip patch antenna is embedded in the top of the frame, the dual-frequency microstrip patch antenna is embedded in the four sides of the frame, and the antenna support frame can be slidably embedded in the bottom along the vertical direction. In this embodiment, an example is given in which the top surface of the shell is composed of a double-layer microstrip patch antenna, the four side surfaces of the shell are composed of four dual-frequency microstrip patch antennas, and the bottom surface of the shell is composed of the base plate 11 of the antenna support frame; the four dual-frequency microstrip patch antennas are respectively fixed on the four side surfaces of the shell in the orthogonal directions of X and Y, and the four dual-frequency microstrip patch antennas all adopt the same structure and design; the dual-frequency microstrip patch antenna and the double-layer microstrip patch antenna both adopt coaxial feeding and use SMA adapters 17 of the same specifications, and there are five SMA adapters 17 in total.

[0046] The double-layer microstrip patch antenna includes an upper antenna and a lower antenna. The upper antenna is located on top of the lower antenna. The upper antenna is completely separated from the lower antenna and has an air gap of a predetermined height, which is used to realize the function of capturing radio frequency energy and sensors; the upper antenna forms the top surface of the shell.

[0047] The four sides of the shell are formed by dual-band microstrip patch antennas and are fixedly connected to the four sides of the upper antenna; the dual-band microstrip patch antenna is used to realize the functions of capturing radio frequency energy and wireless communication; the lower antenna and the dual-band microstrip patch antenna are both coaxially fed by back feeding and are connected to the radio frequency rectifier circuit 14; the antenna support frame forms the bottom surface of the shell and can be slidably limited in the vertical direction between the four sides of the shell to support the lower antenna and change the height of the air gap.

[0048] The transition circuit 12, RF switch 13, RF rectifier circuit 14, energy storage device 16, and control module 15 are all located within the housing and fixedly mounted on the bottom surface of the housing, that is, fixedly mounted on the top surface of the base plate 11. The transition circuit 12 is used to integrate the RF energy captured by the double-layer microstrip patch antenna and the dual-band microstrip patch antenna into the RF rectifier circuit 14; the RF rectifier circuit 14 is used to convert the RF energy into direct current. The RF rectifier circuit 14 includes an impedance matching circuit and a voltage doubler rectifier circuit, both of which use a microstrip line transmission method. The impedance matching section achieves conjugate matching of the input and output impedances, thereby reducing RF power loss; the rectifier section uses a voltage doubler rectifier circuit structure to increase the output voltage, making it suitable for low-power input conditions. When designing the RF rectifier circuit 14, circuit topologies suitable for different input powers can be designed for different application scenarios. Low forward voltage drop, high-efficiency Schottky diodes, such as the SMS7630 series and HSMS286x series, can be used. Preferably, a filter circuit may be provided after the RF rectifier circuit 14 to smooth the rectified DC output, reduce ripples, and provide a stable DC power supply for the subsequent energy storage device 16 .

[0049] The energy storage device 16 is used to store the DC power converted by the RF rectification circuit 14 and supply the power to the control module 15 to achieve self-powered operation; the energy storage device 16 can be a supercapacitor.

[0050] Control module 15 controls RF switch 13 to switch between the dual-band microstrip patch antenna's functions, enabling RF energy capture and wireless communication in different time periods. RF switch 13 must cover the dual-band microstrip patch antenna's operating frequency range. Because RF energy capture systems are sensitive to power loss, devices with low insertion loss should be selected. High isolation between signal paths is also important to ensure that energy capture and communication modes do not interfere with each other. RF switch 13 can be a FET (MOSFET or pHEMT) such as the SKY13350-385LF (0.3 dB insertion loss, 37 dB isolation), the HMC544A (0.6 dB insertion loss, 34 dB isolation, DC-8 GHz), or the Peregrine PE4259 (0.4 dB insertion loss, 42 dB isolation, low-power CMOS process).

[0051] Control module 15 samples the DC output voltage of RF rectifier circuit 14, calculates the rectification efficiency, and transmits this information to the dual-band microstrip patch antenna through data encoding. Control module 15 controls RF switch 13 through time-division multiplexing to switch between RF energy capture and wireless communication. Control module 15 encodes and modulates data for wireless transmission using FSK (Frequency Shift Keying) or QPSK (Quadrature Phase Shift Keying). Control module 15 can utilize a low-power MCU (such as the STM32L431) or a dedicated low-power RF chip (such as the nRF24L01 or CC2500).

[0052] like Figure 3 As shown, the dual-band microstrip patch antenna includes a radiating patch 2, a first dielectric substrate 1, a first metal ground layer 18, and a first coaxial probe feeding structure; the radiating patch 2 is formed on the outer side of the first dielectric substrate 1, arranged in a rectangular shape, and the length and width generally meet the half-wavelength resonance; the first metal ground layer 18 is formed on the inner side of the first dielectric substrate 1; the first coaxial probe feeding structure is composed of an SMA adapter 17 soldered to the radiating patch 2, the first metal ground layer 18, and the first coaxial feeding through hole 3 of the first dielectric substrate 1, which is used to achieve resonance in different frequency bands, so that the dual-band microstrip patch antenna operates in dual frequency bands. Both the radiating patch 2 and the first metal ground layer 18 can be formed on the first dielectric substrate 1 using copper deposition using a PCB process. Feeding points are selected at appropriate locations based on the frequency band requirements and the 50Ω impedance, enabling the antenna to operate in a dual-band mode, enabling the antenna to capture RF energy from different frequency bands and improving RF energy capture efficiency. The radiating patch 2 is tin-plated for oxidation resistance. The inner surface of the first metal ground layer 18 is provided with a solder mask to increase isolation and prevent it from affecting the electrical performance of the circuitry within the housing. Both the radiating patch 2 and the first metal ground layer 18 are rectangular, with the length and width of the radiating patch 2 being smaller than the first dielectric substrate 1. The first metal ground layer 18 completely covers the inner surface of the first dielectric substrate 1. The first dielectric substrate 1 is made of high-strength insulating material. After the dual-band microstrip patch antenna is fabricated, a first coaxial feed hole 3 is drilled at the selected feeding point and soldered using an SMA adapter 17, completing the fabrication of the dual-band microstrip patch antenna.

[0053] like Figure 2 、 Figure 4 and Figure 5As shown, the upper antenna is a parasitic patch 4 antenna; the lower antenna is a main patch antenna; and the parasitic patch 4 antenna is fed via electromagnetic coupling. The parasitic patch 4 antenna includes a second dielectric substrate 5 and a parasitic patch 4 formed on the top surface of the second dielectric substrate 5. Parasitic patch 4 acts as a parasitic coupling unit, increasing the antenna's bandwidth and improving the antenna's overall radiation efficiency through electromagnetic coupling. The parasitic patch 4 is rectangular or circular in shape, with the rectangular shape used as an example in this embodiment. The main patch antenna includes a main radiating patch 6, a third dielectric substrate 7, a second metal ground layer 8, and a second coaxial probe feeding structure. The main radiating patch 6 is formed on the top surface of the third dielectric substrate 7, and the second metal ground layer 8 is formed on the bottom surface of the third dielectric substrate 7. Corresponding second coaxial feeding vias 9 are provided on the main radiating patch 6, the third dielectric substrate 7, and the second metal ground layer 8. The second coaxial probe feeding structure is fixedly mounted to the main radiating patch 6, the third dielectric substrate 7, and the second metal ground layer 8 via the second coaxial feeding vias 9. After the main patch antenna is electromagnetically excited, the induced electromagnetic field will stimulate surface currents and generate resonance. The manufacturing process of the main patch antenna is similar to that of the dual-band microstrip patch antenna, and also adopts the PCB process flow. The size of the main radiating patch 6 and the position of the second coaxial feed through hole 9 are related to the operating frequency band of the double-layer microstrip patch antenna. The lower main patch antenna is bonded to the four antenna support columns 10 and supported by the antenna support frame. The parasitic patch 4 of the upper antenna is slightly smaller than the main radiating patch 6 of the lower antenna, and the second dielectric substrate 5 of the upper antenna and the shell can be made of the same material. The parasitic patch 4 of the upper antenna is suspended above the main patch antenna of the lower antenna, and an air gap of height h is formed between the two. The transmission of radio frequency power between the upper and lower antennas is achieved through electromagnetic coupling.

[0054] When the double-layer microstrip patch antenna is used as a sensor, when the change of physical quantities in the environment (such as pressure, stress strain, vibration displacement, etc.) causes the height h of the air gap to change, the resonant frequency of the antenna will change. At this time, if the power of the RF energy input by the external environment is constant, the RF energy received by the double-layer microstrip patch antenna will decrease, which will in turn cause the rectification efficiency of the subsequent RF rectification circuit 14 to decrease. By monitoring the change of the rectification efficiency through the control module 15, the change of the physical quantity of the external environment can be monitored, thereby playing the role of antenna sensing, thereby realizing the monitoring of the physical quantity in the environment.

[0055] like Figure 2 and Figure 5As shown, the antenna support frame consists of a base plate 11 and four support columns 10. Made of a low-dielectric-constant, smooth, and insulating material, such as polytetrafluoroethylene (Teflon), the base plate 11 forms the bottom surface of the housing and can slide vertically between the four dual-band microstrip patch antennas. The bottom ends of the support columns 10 are fixedly mounted to the top surface of the base plate 11, while the top ends are supported by the bottom surface of the underlying antenna. The four support columns 10 are vertically fixed to the top surface of the base plate 11, ensuring a certain degree of mechanical stability. The antenna support frame and the underlying antenna can slide smoothly and synchronously, thereby changing the air gap height h and achieving the sensing function.

[0056] The above-mentioned transition circuit 12 is a 4:1 type Wilkinson power divider connected by equal-length coaxial lines. Based on the principle of quarter-wavelength impedance transformation, it has four equal-power first input ports and one first output port, and the output end is designed to have a standard impedance of 50Ω to achieve low-loss transmission of RF power; each first input port is connected to a dual-band microstrip patch antenna for integrating RF energy captured by different antennas; the first output port is connected to the RF switch 13; the RF switch 13 has one second input port and two second output ports; the second input port is connected to the output end of the transition circuit 12, one of the second output ports is connected to the RF rectifier circuit 14, and the other second output port is connected to the control module 15.

[0057] The first dielectric substrate 1, the second dielectric substrate 5, the third dielectric substrate 7, and the bottom plate 11 are all made of low-loss dielectric materials to ensure efficient electromagnetic performance when used as antenna substrates while providing sufficient mechanical strength to protect the internal circuitry. High-strength insulating materials can also be used. The dielectric substrates and bottom plate 11 that comprise the housing can be made of FR4 (dielectric constant 4.4, loss tangent 0.02) or Rogers high-frequency laminates, such as RO4350B (dielectric constant 3.48, loss tangent 0.0037) or RT5880 (dielectric constant 2.2, loss tangent 0.0009).

[0058] The self-powered wireless sensor and communication device can realize the RF energy capture and wireless communication functions simultaneously. A RF switch 13 is set between the transition circuit 12 and the RF rectifier circuit 14. The control module 15 controls the RF switch 13 in a time-division multiplexing manner to ensure that RF energy capture and data transmission are performed alternately to avoid mutual interference. Figure 6 As shown, most of the time, the RF switch 13 operates in the energy capture mode; when the change of the physical quantity of the environment causes the change of the rectification efficiency of the RF rectifier circuit 14, the control module 15 samples the DC output voltage of the RF rectifier circuit 14, encodes and modulates the data, and controls the RF switch 13 to switch to the communication mode, and transmits the processed digital signal to the dual-band microstrip patch antenna for transmission, thereby realizing the function of wireless communication.

[0059] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A self-powered wireless sensing and communication device based on radio frequency energy capture, characterized in that: It includes a housing, a dual-band microstrip patch antenna, a double-layer microstrip patch antenna, an antenna support frame, a transition circuit, a radio frequency switch, a radio frequency rectification circuit, an energy storage device, and a control module; The shell has a hollow cubic structure; the double-layer microstrip patch antenna includes an upper antenna and a lower antenna that are completely separated and have an air gap, and are used to achieve the functions of capturing radio frequency energy and sensors; the upper antenna is a parasitic patch antenna; the lower antenna is a main patch antenna; the parasitic patch antenna is fed by electromagnetic coupling; The upper antenna forms the top surface of the housing; the lower antenna is supported at the bottom end of the upper antenna by the antenna support frame; the four side surfaces of the housing are formed by the dual-band microstrip patch antenna and are fixedly connected to the four sides of the upper antenna; the antenna support frame forms the bottom surface of the housing and is slidably positioned between the four side surfaces of the housing in a vertical direction to change the height of the air gap; the dual-band microstrip patch antenna is used to achieve the functions of capturing radio frequency energy and wireless communication; the lower antenna and the dual-band microstrip patch antenna are both coaxially fed using a backfeed method and are connected to the radio frequency rectifier circuit; The transition circuit, the RF switch, the RF rectification circuit, the energy storage device and the control module are all located in the shell and fixedly mounted on the antenna support frame; the transition circuit is used to integrate the RF energy captured by the double-layer microstrip patch antenna and the dual-frequency microstrip patch antenna into the RF rectification circuit; the RF rectification circuit is used to convert the RF energy into direct current; the energy storage device is used to store the electric energy converted by the RF rectification circuit and supply the electric energy to the control module to realize self-powered operation; the control module controls the RF switch to realize function switching of the dual-frequency microstrip patch antenna, and realizes RF energy capture and wireless communication in different time periods.

2. The self-powered wireless sensing and communication device according to claim 1, wherein: The dual-band microstrip patch antenna includes a radiating patch, a first dielectric substrate, a first metal ground layer, and a first coaxial probe feeding structure; the radiating patch is formed on the outer side of the first dielectric substrate; the first metal ground layer is formed on the inner side of the first dielectric substrate; the first coaxial probe feeding structure is composed of an SMA adapter welded to the radiating patch, the first metal ground layer, and the first coaxial feeding through-hole of the first dielectric substrate, and is used to achieve resonance in different frequency bands, so that the dual-band microstrip patch antenna operates in dual frequency bands.

3. The self-powered wireless sensing and communication device according to claim 2, wherein: The radiating patch and the first metal grounding layer are formed on the first dielectric substrate by depositing metal copper; the radiating patch is subjected to an anti-oxidation treatment by tin plating; the inner surface of the first metal grounding layer is provided with a solder resist layer for increasing isolation; the radiating patch and the first metal grounding layer are both rectangular, the length and width of the radiating patch are both smaller than the first dielectric substrate; the first metal grounding layer covers the entire inner surface of the first dielectric substrate; The first dielectric substrate is made of high-strength insulating material.

4. The self-powered wireless sensing and communication device according to claim 1, wherein: The parasitic patch antenna includes a second dielectric substrate and a parasitic patch formed on the top surface of the second dielectric substrate; The parasitic patch serves as a parasitic coupling unit, increases the bandwidth of the antenna through electromagnetic coupling, and improves the overall radiation efficiency of the antenna; the shape of the parasitic patch is rectangular or circular.

5. The self-powered wireless sensing and communication device according to claim 1, wherein: The main patch antenna includes a main radiation patch, a third dielectric substrate, a second metal ground layer and a second coaxial probe feeding structure; The main radiation patch is formed on the top surface of the third dielectric substrate; The second metal grounding layer is formed on the bottom surface of the third dielectric substrate; The second coaxial probe feeding structure is fixedly mounted on the main radiation patch, the third dielectric substrate and the second metal ground layer; When the main patch antenna is electromagnetically excited, the induced electromagnetic field will excite surface currents and generate resonance.

6. The self-powered wireless sensing and communication device according to claim 1, wherein: When the double-layer microstrip patch antenna is used as a sensor, changes in physical quantities in the environment cause changes in the height of the air gap, which causes changes in the antenna resonant frequency, resulting in changes in the efficiency of the radio frequency rectifier circuit, thereby realizing monitoring of physical quantities in the environment.

7. The self-powered wireless sensing and communication device according to any one of claims 1 to 6, wherein: The antenna support frame consists of a base plate and four support columns, and is made of a low-dielectric-constant, smooth and insulating material; the base plate forms the bottom surface of the shell and can be slidably positioned vertically between the four dual-band microstrip patch antennas; the bottom end of the support column is fixedly mounted on the top surface of the base plate, and the top end is supported on the bottom surface of the lower antenna.

8. The self-powered wireless sensing and communication device according to any one of claims 1 to 6, wherein: The transition circuit is a 4:1 type power divider connected by equal-length coaxial lines, having four first input ports and one first output port, each first input port is connected to one of the dual-band microstrip patch antennas, and the first output port is connected to the radio frequency switch; The RF switch has one second input port and two second output ports; the second input port is connected to the output end of the transition circuit, one second output port is connected to the RF rectifier circuit, and the other second output port is connected to the control module.

9. The self-powered wireless sensing and communication device according to claim 8, wherein: The radio frequency rectification circuit includes an impedance matching circuit and a voltage doubling rectification circuit; The energy storage device is a supercapacitor; The control module samples the DC output voltage of the radio frequency rectifier circuit, calculates the rectification efficiency, and transmits the information to the dual-band microstrip patch antenna through data encoding; The control module controls the radio frequency switch in a time-division multiplexing manner to achieve switching between radio frequency energy capture and wireless communication functions.

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