A polarization-adjustable backscatter passive terminal based on rectifier load modulation

Abstract

The embodiments of the present application relate to the field of backscatter communication technology, and disclose a polarization-adjustable backscatter passive terminal based on rectifier load modulation, comprising: a co-aperture orthogonal dual-polarized antenna, an orthogonal coupling circuit, an improved rectifier circuit, a power management circuit, a sensor and an MCU; the horizontal polarization end and the vertical polarization end of the co-aperture orthogonal dual-polarized antenna are respectively connected to the input end and the isolation end of the orthogonal coupling circuit, the orthogonal coupling circuit is connected to the improved rectifier circuit, the improved rectifier circuit is connected to the power management circuit, and the gate of the first transistor and the gate of the second transistor are selectively connected to the MCU; the embodiments of the present application provide a polarization-adjustable backscatter passive terminal based on rectifier load modulation, which introduces a rectifier with a transistor as a load, and according to different connection methods of the transistors, can realize the collection of multi-sensor signals and high-isolation transmission under conditions of no power supply and relatively simple circuits.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of backscatter communication technology, and in particular to a polarization-adjustable backscatter passive terminal based on rectifier load modulation. Background Art

[0002] RFID (Radio Frequency Identification) is a contactless automatic identification technology. Traditional RFID tags typically operate in a specific polarization direction, requiring polarization matching between the RFID tag and RFID reader. Polarization-tunable RFID technology allows users to adjust the polarization direction of RFID tags and RFID readers based on specific applications and environmental requirements, thereby improving communication reliability and performance. Polarization-tunable RFID technology can also reduce multipath interference and signal attenuation, making it effective in complex wireless environments, such as buildings in cities or indoor environments.

[0003] In complex wireless environments, the density of wireless sensor networks is high and sensor nodes are deployed very closely together. Therefore, high isolation between wireless sensors is required, and orthogonal polarization isolation of signals is usually used.

[0004] In their paper, "A depolarizing chipless RFID tag for robust detection and its FCC-compliant UWB reading system," V. Vena A. et al. proposed a polarization-variable passive RFID tag with dual L-shaped resonators. This tag has a simple structure, requires no battery power, and can achieve orthogonal polarization shifts in reflected signals. However, it can only achieve linear-to-linear polarization reflection shifts, and the shift angle is uncontrollable. Therefore, it can only isolate uplink and downlink channels and cannot achieve close-range multi-target channel isolation.

[0005] Patent publication number CN105139047A discloses a variable polarization chipless RFID system. This system incorporates a system solution for arbitrarily controlling polarization, including a dual signal source for generating RF signals with arbitrarily controllable phases; horizontal and vertical polarization branches for adjusting amplitudes; and a dual-polarization antenna for superimposing electromagnetic waves with arbitrary polarizations. This system can achieve channel isolation for multiple short-range sensors, but it includes several complex components, such as a controllable attenuator and dual signal sources for generating arbitrary phases, and requires battery power. Summary of the Invention

[0006] The purpose of the embodiments of the present application is to provide a polarization-adjustable backscatter passive terminal based on rectifier load modulation, aiming to solve the technical problem that high isolation between wireless sensors is required in complex wireless environments, but the orthogonal polarization isolation method proposed for this cannot achieve channel isolation of multiple targets at close range or its system is relatively complex. The present application introduces a rectifier with a transistor as the load. According to different connection methods of the transistors, an orthogonal polarization deflection signal, a left-hand circular polarization signal and a right-hand circular polarization signal can be obtained. Then, through the coordination of the original signal and the orthogonal polarization deflection signal and the left-hand circular polarization signal and the right-hand circular polarization signal, the acquisition of multi-sensor signals and high-isolation transmission can be achieved under the conditions of no power supply and relatively simple circuits.

[0007] To solve the above technical problems, in the first aspect, an embodiment of the present application provides a polarization-adjustable backscatter passive terminal based on rectifier load modulation, including: a common-aperture orthogonal dual-polarization antenna, an orthogonal coupling circuit, an improved rectifier circuit, a power management circuit, a sensor and an MCU; the improved rectifier circuit includes a first rectifier, a second rectifier, a first transistor and a second transistor, the load of the first rectifier is the first transistor, the load of the second rectifier is the second transistor, the orthogonal coupling circuit includes an input end, an isolation end, a through end and a coupling end, and the common-aperture orthogonal dual-polarization antenna includes a horizontal polarization end and a vertical polarization end; the horizontal polarization end of the common-aperture orthogonal dual-polarization antenna is connected to the input end of the orthogonal coupling circuit, the vertical polarization end of the common-aperture orthogonal dual-polarization antenna is connected to the isolation end of the orthogonal coupling circuit, the through end of the orthogonal coupling circuit is connected to the first rectifier, the coupling end of the orthogonal coupling circuit is connected to the second rectifier, and the first rectifier is connected through the first The DC interface is connected to the power management circuit, the second rectifier is connected to the power management circuit through the second DC interface, the gate of the first transistor and the gate of the second transistor can be selectively connected to the MCU, and the sensor and the power management circuit are both connected to the MCU; the common-aperture orthogonal dual-polarized antenna is used to receive and radiate electromagnetic waves, the orthogonal coupling circuit is used to evenly divide the electromagnetic waves received at the input end into the through end and the coupling end, the first rectifier and the second rectifier are both used to rectify the received electromagnetic waves into direct current, the power management circuit is used to boost or buck the direct current to power the sensor and the MCU, the sensor is used to obtain a sensing signal of the target environment, the MCU is used to convert the sensing signal into a control level, and use the control level to control the gate voltage of the first transistor and the gate voltage of the second transistor, the orthogonal coupling circuit is also used to receive the electromagnetic wave modulated by the MCU, and transmit the electromagnetic wave modulated by the MCU to the common-aperture orthogonal dual-polarized antenna.

[0008] The embodiment of the present application provides a polarization-adjustable backscatter passive terminal based on rectifier load modulation, which is aimed at the need for high isolation between wireless sensors in complex wireless environments. However, the orthogonal polarization isolation method proposed for this purpose cannot achieve channel isolation of multiple targets at close range or its system is relatively complex. The embodiment of the present application introduces a rectifier with a transistor as a load. According to different connection methods of the transistors, the original signal, the orthogonal polarization deflection signal, the left-hand circular polarization signal and the right-hand circular polarization signal can be obtained. Then, by utilizing the characteristics that the original signal and the orthogonal polarization deflection signal are two mutually orthogonal signals and the left-hand circular polarization signal and the right-hand circular polarization signal are two mutually orthogonal signals, the acquisition of multi-sensor signals and the high-isolation transmission of multi-sensor signals can be achieved without power supply and with a relatively simple circuit.

[0009] In some optional embodiments, the gate of the first transistor and the gate of the second transistor are selectively connected to the MCU, including: the gate of the first transistor and the gate of the second transistor are both connected to the MCU, the gate of the first transistor and the gate of the second transistor are not connected to the MCU, the gate of the first transistor is connected to the MCU and the gate of the second transistor is not connected to the MCU, and the gate of the second transistor is connected to the MCU and the gate of the first transistor is not connected to the MCU.

[0010] In some optional embodiments, the first rectifier includes a first diode and a first filter capacitor, and the second rectifier includes a second diode and a second filter capacitor; the first filter capacitor, the first DC interface, and the first transistor are connected in parallel, and the first filter capacitor, the first DC interface, the first transistor and the first diode are connected in series; the second filter capacitor, the second DC interface, and the second transistor are connected in parallel, and the second filter capacitor, the second DC interface, the second transistor and the second diode are connected in series.

[0011] In some optional embodiments, drains of the first transistor and the second transistor are both grounded.

[0012] On the second aspect, another embodiment of the present application proposes a polarization-adjustable backscatter terminal multi-device close-range sensing method, which is suitable for sensing two closely placed polarization-adjustable backscatter passive terminals based on rectifier load modulation, including: the reader emits a linearly polarized electromagnetic wave, and the two closely placed polarization-adjustable backscatter passive terminals based on rectifier load modulation receive the linearly polarized electromagnetic wave and radiate two mutually orthogonal signals to the reader for sensing isolation; the reader performs sensing based on the two mutually orthogonal signals.

[0013] In some optional embodiments, the two closely placed polarization-adjustable backscatter passive terminals based on rectifier load modulation are a first polarization-adjustable backscatter passive terminal and a second polarization-adjustable backscatter passive terminal, the gate of the first transistor and the gate of the second transistor of the first polarization-adjustable backscatter passive terminal are both connected to the MCU, and the gate of the first transistor and the gate of the second transistor of the second polarization-adjustable backscatter passive terminal are not connected to the MCU.

[0014] In some optional embodiments, the two closely placed polarization-adjustable backscatter passive terminals based on rectifier load modulation are a third polarization-adjustable backscatter passive terminal and a fourth polarization-adjustable backscatter passive terminal, the gate of the first transistor of the third polarization-adjustable backscatter passive terminal is connected to the MCU and the gate of the second transistor is not connected to the MCU, and the gate of the second transistor of the fourth polarization-adjustable backscatter passive terminal is connected to the MCU and the gate of the first transistor is not connected to the MCU. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments are exemplarily described by the figures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments.

[0016] Figure 1 This is a schematic diagram of a polarization-adjustable backscatter passive terminal based on rectifier load modulation provided in Example 1 of the present application;

[0017] Figure 2 is an equivalent circuit diagram of Example 1 of the present application;

[0018] Figure 3 is an equivalent circuit diagram of Example 2 of the present application;

[0019] Figure 4 is an equivalent circuit diagram of Example 3 of the present application;

[0020] Figure 5 is an equivalent circuit diagram of Example 4 of the present application;

[0021] Figure 6 is a schematic diagram of Example 5 of the present application;

[0022] Figure 7 is a schematic diagram of Example 6 of the present application;

[0023] In the figure: 1. Common-aperture orthogonal dual-polarization antenna; 2. Orthogonal coupling circuit; 3. Improved rectifier circuit; 4. Power management circuit; 5. Sensor; 6. MCU; 11. Horizontal polarization end; 12. Vertical polarization end; 31. First rectifier; 32. Second rectifier; 311. First transistor; 321. Second transistor; 312. First filter capacitor; 322. Second filter capacitor; 313. First diode; 323. Second diode. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, each embodiment of the present application will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in each embodiment of the present application, many technical details are proposed to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation of the present application. The various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0025] Example 1

[0026] Embodiment 1 of the present application provides a polarization-adjustable backscatter passive terminal based on rectifier load modulation, such as Figure 1 As shown, the device comprises: a common-aperture orthogonal dual-polarized antenna 1, an orthogonal coupling circuit 2, an improved rectifier circuit 3, a power management circuit 4, a sensor 5, and an MCU. The improved rectifier circuit 3 comprises a first rectifier 31 and a second rectifier 32. The load of the first rectifier 31 is a first transistor 311, and the load of the second rectifier 32 is a second transistor 321. The orthogonal coupling circuit 2 comprises an input terminal, an isolation terminal, a through terminal, and a coupling terminal. The common-aperture orthogonal dual-polarized antenna 1 comprises a horizontal polarization terminal 11 and a vertical polarization terminal 12. It should be noted that the MCU stands for microcontroller unit.

[0027] The horizontal polarization end 11 and the vertical polarization end 12 of the co-aperture orthogonal dual-polarization antenna 1 are respectively connected to the input end and the isolation end of the orthogonal coupling circuit 2, the through end of the orthogonal coupling circuit 2 is connected to the first rectifier 31, the coupling end of the orthogonal coupling circuit 2 is connected to the second rectifier 32, the first rectifier 31 is connected to the power management circuit 4 through the first DC interface, the second rectifier 32 is connected to the power management circuit 4 through the second DC interface, the gate of the first transistor 311 and the gate of the second transistor 321 are respectively connected to the MCU, and the sensor 5 is connected to the power management circuit 4 and the MCU.

[0028] See also Figure 2 , Figure 2An equivalent circuit diagram of Example 1 of the present application is shown. It should be noted that, in the embodiment of the present application, each rectifier includes a filter capacitor and a diode, and a transistor is used as a load. In this embodiment, the source of the first transistor 311 and the source of the second transistor 321 are connected to the first diode 313 and the second diode 323 respectively, and the drain of the first transistor 311 and the drain of the second rectifier 32 are both grounded. The first rectifier 31 includes a first filter capacitor 312 and a first diode 313, and the second rectifier 32 includes a second filter capacitor 322 and a second diode 323; the first filter capacitor 312, the first DC interface, and the first transistor 311 are connected in parallel, the first transistor 311 and the first diode 313, the first filter capacitor 312, and the first DC interface are connected in series, the second filter capacitor 322, the second DC interface, and the second transistor 321 are connected in parallel, and the second transistor 321 and the second diode 323, the second filter capacitor 312, and the second DC interface are connected in series.

[0029] The horizontally polarized end 11 of the co-aperture orthogonal dual-polarized antenna 1 receives the initial electromagnetic wave and transmits the initial electromagnetic wave to the input end of the orthogonal coupling circuit 2. The orthogonal coupling circuit 2 evenly divides the initial electromagnetic wave received at the input end into the through end and the coupling end. The sensor 5 obtains a sensing signal of the target environment, and the MCU converts the sensing signal into a control level. Since the gate of the first transistor 311 and the gate of the second transistor 321 are respectively connected to the MCU, the resistance of the first transistor 311, the load of the first rectifier 31, and the resistance of the second transistor 321, the load of the second rectifier 32, are controlled by the MCU control level. The initial electromagnetic wave received by the first rectifier 31 and the second rectifier 32 is modulated by the MCU. The modulated electromagnetic wave is recorded as an electromagnetic wave carrying information. The orthogonal coupling circuit 2 couples the electromagnetic wave carrying information to the isolation end. The isolation end excites the vertically polarized end 12 of the co-aperture orthogonal dual-polarized antenna 1 to radiate an electromagnetic wave carrying information. The radiated electromagnetic wave carrying information is recorded as an orthogonal polarization deflection signal. It should be noted that the first rectifier 31 and the second rectifier 32 are also used to rectify the received initial electromagnetic wave into direct current, and the power management circuit 4 boosts or steps down the direct current to power the sensor 5 and the MCU.

[0030] Example 2

[0031] Embodiment 2 of the present application provides a polarization-adjustable backscatter passive terminal based on rectifier load modulation, such as Figure 3 As shown, Figure 3An equivalent circuit diagram of Example 2 of the present application is presented. Example 2 of the present application provides a polarization-adjustable backscatter passive terminal based on rectifier load modulation, including: a common-aperture orthogonal dual-polarization antenna 1, an orthogonal coupling circuit 2, an improved rectifier circuit 3, a power management circuit 4, a sensor 5 and an MCU; the improved rectifier circuit 3 includes a first rectifier 31 and a second rectifier 32, the load of the first rectifier 31 is a first transistor 311, and the load of the second rectifier 32 is a second transistor 321, the orthogonal coupling circuit 2 includes an input end, an isolation end, a through end and a coupling end, the common-aperture orthogonal dual-polarization antenna 1 includes a horizontal polarization end 11 and a vertical polarization end 12, the first rectifier 31 includes a first filter capacitor 312 and a first diode 313, and the second rectifier 32 includes a second filter capacitor 322 and a second diode 323.

[0032] The horizontal polarization end 11 and the vertical polarization end 12 of the co-aperture orthogonal dual-polarization antenna 1 are respectively connected to the input end and the isolation end of the orthogonal coupling circuit 2, the through end of the orthogonal coupling circuit 2 is connected to the first rectifier 31, the coupling end of the orthogonal coupling circuit 2 is connected to the second rectifier 32, the first rectifier 31 is connected to the power management circuit 4 through a first DC interface, the second rectifier 32 is connected to the power management circuit 4 through a second DC interface, the sensor 5 is connected to the power management circuit 4 and the MCU, the source of the first transistor 311 and the source of the second transistor 321 are respectively connected to the first diode 313 and the second diode 323, and the drain of the first transistor 311 and the drain of the second rectifier 32 are both grounded.

[0033] Figure 3 In the embodiment, since the working states of the first transistor 311 and the second transistor 321 remain unchanged, in this embodiment, the first transistor 311 and the second transistor 321 are equivalent to resistors with constant resistance.

[0034] The horizontally polarized end 11 of the co-aperture orthogonal dual-polarized antenna 1 receives the initial electromagnetic wave and transmits the initial electromagnetic wave to the input end of the orthogonal coupling circuit 2. The orthogonal coupling circuit 2 evenly divides the initial electromagnetic wave received at the input end into the through end and the coupling end. The first rectifier 31 and the second rectifier 32 rectify the received initial electromagnetic wave into direct current. The power management circuit 4 boosts or steps down the direct current to power the sensor 5 and the MCU. Due to the nonlinear characteristics of the first diode 313 and the second diode 323 in the first rectifier 31 and the second rectifier 32, the orthogonal coupling circuit 2 couples the initial electromagnetic waves at the through end and the coupling end to the isolation end. The isolation end excites the vertically polarized end 12 of the co-aperture orthogonal dual-polarized antenna 1 to radiate the initial electromagnetic wave, and the radiated initial electromagnetic wave is recorded as the original signal.

[0035] Example 3

[0036] Embodiment 3 of the present application provides a polarization-adjustable backscatter passive terminal based on rectifier load modulation, such as Figure 4 As shown, Figure 4 An equivalent circuit diagram of Example 3 of the present application is presented. Example 3 of the present application provides a polarization-adjustable backscatter passive terminal based on rectifier load modulation, including: a common-aperture orthogonal dual-polarization antenna 1, an orthogonal coupling circuit 2, an improved rectifier circuit 3, a power management circuit 4, a sensor 5 and an MCU; the improved rectifier circuit 3 includes a first rectifier 31 and a second rectifier 32, the load of the first rectifier 31 is a first transistor 311, and the load of the second rectifier 32 is a second transistor 321, the orthogonal coupling circuit 2 includes an input end, an isolation end, a through end and a coupling end, the common-aperture orthogonal dual-polarization antenna 1 includes a horizontal polarization end 11 and a vertical polarization end 12, the first rectifier 31 includes a first filter capacitor 312 and a first diode 313, and the second rectifier 32 includes a second filter capacitor 322 and a second diode 323.

[0037] The horizontal polarization end 11 and the vertical polarization end 12 of the co-aperture orthogonal dual-polarization antenna 1 are respectively connected to the input end and the isolation end of the orthogonal coupling circuit 2, the through end of the orthogonal coupling circuit 2 is connected to the first rectifier 31, the coupling end of the orthogonal coupling circuit 2 is connected to the second rectifier 32, the first rectifier 31 is connected to the power management circuit 4 through a first DC interface, the second rectifier 32 is connected to the power management circuit 4 through a second DC interface, the gate of the first transistor 311 is connected to the MCU, the sensor 5 is connected to the power management circuit 4 and the MCU, the source of the first transistor 311 and the source of the second transistor 321 are respectively connected to the first diode 313 and the second diode 323, and the drain of the first transistor 311 and the drain of the second rectifier 32 are both grounded.

[0038] Figure 4 In the embodiment, since the working state of the second transistor 321 remains unchanged, the second transistor 321 is equivalent to a resistor with a constant resistance value.

[0039] The horizontal polarization end 11 of the orthogonal dual-polarization antenna 1 with a common aperture receives the initial electromagnetic wave and transmits the initial electromagnetic wave to the input end of the orthogonal coupling circuit 2. The orthogonal coupling circuit 2 evenly divides the initial electromagnetic wave received at the input end to the through end and the coupling end, which is recorded as the average electromagnetic wave. The sensor 5 obtains the sensing signal of the target environment, and the MCU converts the sensing signal into a control level. Since the gate of the first transistor 311 is connected to the MCU, the resistance of the load first transistor 311 of the first rectifier 31 is controlled by the MCU control level, and the average electromagnetic wave received by the first rectifier 31 is controlled by the MCU control level. MCU modulation, the modulated equalized electromagnetic wave is recorded as the first modulated electromagnetic wave, the orthogonal coupling circuit 2 couples the first modulated electromagnetic wave to the isolation end and the input end. Since the working state of the second transistor 321 remains unchanged, the equalized electromagnetic wave received by the second rectifier 32 is absorbed by the load and is not reflected. The horizontal polarization end 11 and the vertical polarization end 12 of the co-aperture orthogonal dual-polarization antenna 1 radiate the first modulated electromagnetic wave. Since the first modulated electromagnetic waves radiated from the two ports have equal power and a phase difference of 90°, the two first modulated electromagnetic waves will generate left-handed circularly polarized signals in the air.

[0040] It should be noted that the first rectifier 31 and the second rectifier 32 are also used to rectify the received equally distributed electromagnetic waves into direct current, and the power management circuit 4 boosts or steps down the direct current to power the sensor 5 and the MCU.

[0041] Example 4

[0042] Embodiment 4 of the present application provides a polarization-adjustable backscatter passive terminal based on rectifier load modulation, such as Figure 5 As shown, Figure 5 An equivalent circuit diagram of Example 4 of the present application is presented. Example 4 of the present application provides a polarization-adjustable backscatter passive terminal based on rectifier load modulation, including: a common-aperture orthogonal dual-polarization antenna 1, an orthogonal coupling circuit 2, an improved rectifier circuit 3, a power management circuit 4, a sensor 5 and an MCU; the improved rectifier circuit 3 includes a first rectifier 31 and a second rectifier 32, the load of the first rectifier 31 is a first transistor 311, and the load of the second rectifier 32 is a second transistor 321, the orthogonal coupling circuit 2 includes an input end, an isolation end, a through end and a coupling end, the common-aperture orthogonal dual-polarization antenna 1 includes a horizontal polarization end 11 and a vertical polarization end 12, the first rectifier 31 includes a first filter capacitor 312 and a first diode 313, and the second rectifier 32 includes a second filter capacitor 322 and a second diode 323.

[0043] The horizontal polarization end 11 and the vertical polarization end 12 of the co-aperture orthogonal dual-polarization antenna 1 are respectively connected to the input end and the isolation end of the orthogonal coupling circuit 2, the through end of the orthogonal coupling circuit 2 is connected to the first rectifier 31, the coupling end of the orthogonal coupling circuit 2 is connected to the second rectifier 32, the first rectifier 31 is connected to the power management circuit 4 through a first DC interface, the second rectifier 32 is connected to the power management circuit 4 through a second DC interface, the gate of the second transistor 321 is connected to the MCU, the sensor 5 is connected to the power management circuit 4 and the MCU, the source of the first transistor 311 and the source of the second transistor 321 are respectively connected to the first diode 313 and the second diode 323, and the drain of the first transistor 311 and the drain of the second rectifier 32 are both grounded.

[0044] Figure 5 In the embodiment, since the working state of the first transistor 311 remains unchanged, the first transistor 311 is equivalent to a resistor with a constant resistance value.

[0045] The horizontal polarization end 11 of the orthogonal dual-polarization antenna 1 with a common aperture receives the initial electromagnetic wave and transmits the initial electromagnetic wave to the input end of the orthogonal coupling circuit 2. The orthogonal coupling circuit 2 evenly divides the initial electromagnetic wave received at the input end to the through end and the coupling end, which is recorded as the average electromagnetic wave. The sensor 5 obtains the sensing signal of the target environment, and the MCU converts the sensing signal into a control level. Since the gate of the second transistor 321 is connected to the MCU, the resistance of the load second transistor 321 of the second rectifier 32 is controlled by the MCU control level, and the average electromagnetic wave received by the second rectifier 32 is controlled by the MCU control level. MCU modulation, the modulated equalized electromagnetic wave is recorded as the second modulated electromagnetic wave, the orthogonal coupling circuit 2 couples the second modulated electromagnetic wave to the isolation end and the input end. Since the working state of the first transistor 311 remains unchanged, the equalized electromagnetic wave received by the first rectifier 31 is absorbed by the load and is not reflected. The horizontal polarization end 11 and the vertical polarization end 12 of the co-aperture orthogonal dual-polarization antenna 1 radiate the second modulated electromagnetic wave. Since the second modulated electromagnetic waves radiated from the two ports have equal power and a phase difference of 90°, the two first modulated electromagnetic waves will generate right-hand circularly polarized signals in the air.

[0046] It should be noted that the first rectifier 31 and the second rectifier 32 are also used to rectify the received equally distributed electromagnetic waves into direct current, and the power management circuit 4 boosts or steps down the direct current to power the sensor 5 and the MCU.

[0047] Example 5

[0048] This embodiment 5 is based on the embodiments 1 and 2, and proposes a short-range sensing method using a polarization-adjustable backscatter passive terminal based on rectifier load modulation in embodiment 1 and a polarization-adjustable backscatter passive terminal based on rectifier load modulation in embodiment 2.

[0049] See also Figure 6 , a polarization-adjustable backscatter passive terminal based on rectifier load modulation in Example 1 and a polarization-adjustable backscatter passive terminal based on rectifier load modulation in Example 2 are placed in close proximity, the antenna of the reader / writer emits linearly polarized electromagnetic waves, and the polarization-adjustable backscatter passive terminal based on rectifier load modulation in Example 1 and the polarization-adjustable backscatter passive terminal based on rectifier load modulation in Example 2 receive the linearly polarized electromagnetic waves and radiate orthogonal polarization deflection signals and original signals respectively.

[0050] It should be noted that the orthogonal polarization deflection signal and the original signal are two mutually orthogonal signals. The polarization-adjustable backscatter terminal multi-device short-range sensing method of this embodiment 5 can make the two uplink channels polarized orthogonally to each other, have high isolation characteristics, and can realize the high-isolation transmission of multiple sensor signals while collecting multiple sensor signals.

[0051] Example 6

[0052] This embodiment 6 is based on the embodiments 3 and 4, and proposes a short-range sensing method using a polarization-adjustable backscatter passive terminal based on rectifier load modulation in embodiment 3 and a polarization-adjustable backscatter passive terminal based on rectifier load modulation in embodiment 4.

[0053] See also Figure 7 , a polarization-adjustable backscatter passive terminal based on rectifier load modulation in Example 3 and a polarization-adjustable backscatter passive terminal based on rectifier load modulation in Example 4 are placed in close proximity, the antenna of the reader / writer emits linearly polarized electromagnetic waves, and a polarization-adjustable backscatter passive terminal based on rectifier load modulation in Example 3 and a polarization-adjustable backscatter passive terminal based on rectifier load modulation in Example 2 receive linearly polarized electromagnetic waves and radiate left-hand circularly polarized signals and right-hand circularly polarized signals, respectively.

[0054] It should be noted that the left-hand circularly polarized signal and the right-hand circularly polarized signal are two mutually orthogonal signals. The polarization-adjustable backscatter terminal multi-device close-range sensing method of this embodiment 6 can make the two uplink channels polarized orthogonally to each other, have high isolation characteristics, and can realize the high-isolation transmission of multiple sensor signals while collecting multiple sensor signals.

[0055] Adding insignificant modifications or introducing insignificant designs to the circuits of the embodiments of the present application without changing the core design of the circuits are all within the scope of protection of this application.

[0056] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present application, and that in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A polarization-adjustable backscatter passive terminal based on rectifier load modulation, characterized in that: include: Co-aperture orthogonal dual-polarization antenna, orthogonal coupling circuit, improved rectification circuit, power management circuit, sensor and MCU; The improved rectifier circuit includes a first rectifier, a second rectifier, a first transistor, and a second transistor. The load of the first rectifier is the first transistor, and the load of the second rectifier is the second transistor. The orthogonal coupling circuit includes an input end, an isolation end, a through end, and a coupling end. The co-aperture orthogonal dual-polarization antenna includes a horizontal polarization end and a vertical polarization end. The horizontal polarization end of the co-aperture orthogonal dual-polarization antenna is connected to the input end of the orthogonal coupling circuit, the vertical polarization end of the co-aperture orthogonal dual-polarization antenna is connected to the isolation end of the orthogonal coupling circuit, the through end of the orthogonal coupling circuit is connected to the first rectifier, the coupling end of the orthogonal coupling circuit is connected to the second rectifier, the first rectifier is connected to the power management circuit through a first DC interface, the second rectifier is connected to the power management circuit through a second DC interface, the gate of the first transistor and the gate of the second transistor are optionally connected to the MCU, and the sensor and the power management circuit are both connected to the MCU; The common-aperture orthogonal dual-polarized antenna is used to receive and radiate electromagnetic waves. The orthogonal coupling circuit is used to evenly distribute the electromagnetic waves received at the input end to the through end and the coupling end. The first rectifier and the second rectifier are both used to rectify the received electromagnetic waves into direct current. The power management circuit is used to boost or buck the direct current to power the sensor and the MCU. The sensor is used to obtain the sensor signal of the target environment. The MCU is used to convert the sensor signal into a control level and use the control level to control the gate voltage of the first transistor and the gate voltage of the second transistor. The orthogonal coupling circuit is also used to receive the electromagnetic waves modulated by the MCU and transmit the electromagnetic waves modulated by the MCU to the common-aperture orthogonal dual-polarized antenna.

2. The polarization-adjustable backscatter passive terminal based on rectifier load modulation according to claim 1, characterized in that: The gate of the first transistor and the gate of the second transistor are selectively connected to the MCU, including: the gate of the first transistor and the gate of the second transistor are both connected to the MCU, the gate of the first transistor and the gate of the second transistor are not connected to the MCU, the gate of the first transistor is connected to the MCU and the gate of the second transistor is not connected to the MCU, and the gate of the second transistor is connected to the MCU and the gate of the first transistor is not connected to the MCU.

3. The polarization-adjustable backscatter passive terminal based on rectifier load modulation according to claim 1, characterized in that: The first rectifier includes a first diode and a first filter capacitor, and the second rectifier includes a second diode and a second filter capacitor; An anode of the first diode is connected to the through terminal of the orthogonal coupling circuit, a cathode of the first diode is connected to the source of the first transistor and the first DC interface in sequence, the first filter capacitor is connected between the source and drain of the first transistor, and the drain of the first transistor is grounded; The anode of the second diode is connected to the coupling end of the orthogonal coupling circuit, the cathode of the second diode is connected to the source of the second transistor and the second DC interface in sequence, the second filter capacitor is connected between the source and drain of the second transistor, and the drain of the second transistor is grounded.

4. The polarization-adjustable backscatter passive terminal based on rectifier load modulation according to claim 3, characterized in that: Drains of the first transistor and the second transistor are both grounded.

5. A short-range sensing method, suitable for sensing two closely placed polarization-adjustable backscatter passive terminals based on rectifier load modulation as claimed in any one of claims 1 to 4, characterized in that: The method comprises: The reader emits a linearly polarized electromagnetic wave. Two closely placed polarization-adjustable backscattering passive terminals based on rectifier load modulation receive the linearly polarized electromagnetic wave and radiate two mutually orthogonal signals to the reader for sensor isolation. The reader performs sensing based on two mutually orthogonal signals.

6. A short-range sensing method according to claim 5, characterized in that: The two closely placed polarization-adjustable backscatter passive terminals based on rectifier load modulation are a first polarization-adjustable backscatter passive terminal and a second polarization-adjustable backscatter passive terminal. The gate of the first transistor and the gate of the second transistor of the first polarization-adjustable backscatter passive terminal are both connected to the MCU, and the gate of the first transistor and the gate of the second transistor of the second polarization-adjustable backscatter passive terminal are not connected to the MCU.

7. The short-range sensing method according to claim 5, characterized in that: The two closely placed polarization-adjustable backscatter passive terminals based on rectifier load modulation are a third polarization-adjustable backscatter passive terminal and a fourth polarization-adjustable backscatter passive terminal. The gate of the first transistor of the third polarization-adjustable backscatter passive terminal is connected to the MCU and the gate of the second transistor is not connected to the MCU. The gate of the second transistor of the fourth polarization-adjustable backscatter passive terminal is connected to the MCU and the gate of the first transistor is not connected to the MCU.

Images