A method of wireless information transmission combining defect structures and harmonic reflections

Abstract

The application discloses a wireless information transmission system and method combining defect ground structure and harmonic reflection, which uses the second harmonic generated by the nonlinear characteristics of a rectifier diode as an information carrier, and encodes the rectifier output voltage information in the frequency selective reflection characteristics of the second harmonic through a defect ground structure band-stop filter, so that the feedback components such as voltage sampling chips and transmission lines are not needed at the receiving end, the problems such as structural complexity and cost increase caused by the traditional feedback circuit are avoided, and passive and non-contact output voltage feedback is realized; meanwhile, the application analyzes the second harmonic signal spectrum reflected from the receiving end through the transmitting end, identifies the frequency corresponding to the strength notch point, reversely obtains the real-time output voltage value according to the mapping relationship between the frequency and the rectifier output voltage, and thus realizes voltage state monitoring without active signal transmission of the receiving end.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology, specifically relating to a wireless information transmission system and method with combined defective ground structure and harmonic reflection. Background Technology

[0002] With the rapid evolution of fifth-generation (5G) communication and Internet of Things (IoT) technologies, wireless information transmission systems are increasingly widely used in various mobile and embedded devices. As a key component of the system, the radio frequency (RF) rectifier is responsible for converting received RF energy into DC output, and its performance directly affects information transmission efficiency and system stability. On the one hand, in the field of implantable biomedical devices, wireless information transmission systems (such as pacemakers, neurostimulators, and implantable blood glucose monitors) require long-term stable wireless power supply, necessitating real-time acquisition of rectified output voltage information to determine if the device is in a normal power supply state and avoid device failure due to insufficient power. On the other hand, in the IoT field, wireless information transmission systems (such as smart home sensors and industrial wireless monitoring nodes) often rely on RF wireless power to maintain operation, requiring monitoring of the rectified output voltage to understand the node's energy status in real time. When the voltage is too low, the transmitter can automatically adjust the transmission power to ensure continuous node operation.

[0003] However, in real-world dynamic environments, the input power and load conditions at the receiver often fluctuate, easily leading to rectifier impedance mismatch and consequently affecting output efficiency and reliability. Traditional solutions typically rely on additional wired or wireless communication modules for output feedback and status monitoring, which not only increases system complexity and power consumption but also fails to meet the trends of lightweight and integrated design. Therefore, achieving efficient and accurate rectifier output voltage feedback without requiring an additional communication link has become a key technical challenge for improving the intelligence and robustness of wireless information transmission systems. Existing methods for achieving rectifier output voltage feedback are as follows:

[0004] (1) Wireless power control method based on harmonic feedback

[0005] like Figure 1 As shown, the diode in the receiver circuit exhibits linearity when the transmit power is insufficient, but becomes nonlinear when the transmit power exceeds the diode's conduction threshold. At this point, the backscattered harmonic components will produce abrupt changes. The transmitter determines the operating state of the receiver circuit by detecting these abrupt changes in harmonic power, thus enabling power level monitoring without modifying the receiver. The following problems exist:

[0006] 1. Interruption of energy transmission during threshold point detection: When this control method searches for the power threshold point for calibration, it must start scanning the transmitted signal from a low power level, causing the receiving device to temporarily lose power and interrupt its function during the detection period because the power is lower than the operating threshold.

[0007] 2. Poor robustness to weak coupling: When the implanted device is located deep or far from the transmitter and the angle deviation is large, the power obtained by the receiving circuit is low, and the harmonic signal it generates becomes extremely weak. It is easily submerged by environmental noise or harmonics generated by the nonlinearity of the transmitter itself, making it difficult for the transmitter to detect the critical harmonic abrupt change point.

[0008] (2) RFID (Radio Frequency Identification) Closed-Loop Remote Control Wireless Power Supply System

[0009] like Figure 2 As shown, the system monitors the output voltage by continuously comparing the rectified DC voltage with a precision reference voltage. Once the voltage exceeds a set threshold (e.g., 3.6V), an LSK (Load Shift Keying) modulation process is immediately initiated—that is, an additional load connected to the rectifier circuit is periodically switched via a switching transistor, thereby periodically changing the amount of current drawn from the electromagnetic field by the implanted coil. This load change modulates the signal amplitude reflected back to the transmitting coil, forming a series of externally identifiable "overvoltage" pulses. An externally integrated RFID reader chip specifically detects this load modulation signal generated by LSK, decodes it into logic instructions, and transmits them to the microcontroller. The problems with this RFID closed-loop remote control wireless power supply system are as follows:

[0010] 1. Feedback information is a coarse binary state, not a precise value: The feedback information is digital and binary. The system can only determine whether the voltage is higher than a certain threshold (e.g., 3.6V) and send back a "yes" or "no" pulse signal. It cannot tell you the specific value of the voltage, nor can it distinguish "how much higher" or "how much lower".

[0011] 2. Structural complexity: The receiver includes voltage sampling circuitry, comparators, a reference voltage source, a logic control unit, and load modulation switches (such as MOSFETs). These circuits not only increase the complexity, size, and cost of the receiver, but also consume a portion of the received energy to operate.

[0012] (3) SWIPT (Wireless Powered Communication) rectifier circuit based on second harmonic communication

[0013] like Figure 3As shown, the received RF signal in this circuit first passes through the input matching network of the integrated duplexer to achieve impedance matching and separation between the fundamental frequency signal and the second harmonic. The fundamental frequency signal enters a series diode for rectification, converting it into DC energy to supply the load. Simultaneously, the nonlinear characteristics of the diode generate a second harmonic containing the same information. The pass-through filter is designed to totally reflect the fundamental frequency and harmonics, but it exhibits a specific impedance at the second harmonic frequency, allowing the second harmonic to be extracted by the matching network and output for communication. The third harmonic is reflected back to the diode to participate in rectification again to improve energy efficiency. The problem with the SWIPT rectifier circuit based on second harmonic communication is that the pass-through filter needs to totally reflect the fundamental frequency and higher harmonics, but when extracting the second harmonic, it needs to be coupled to the output port through a matching network. This process may introduce insertion loss and impedance mismatch. Summary of the Invention

[0014] The purpose of this invention is to provide a wireless information transmission system and method that combines defective ground structures and harmonic reflections.

[0015] In a first aspect, the present invention provides a wireless information transmission system with combined defective ground structure and harmonic reflection, comprising a transmitter and a receiver; the transmitter includes a signal source and a transmitting antenna; the receiver includes a receiving antenna, a rectifier and a load;

[0016] The receiving end also includes a defective ground structure band-stop filter; a varactor diode is added to the defect slot of the defective ground structure band-stop filter; the varactor diode is used to adjust the equivalent capacitance of the defective ground structure band-stop filter according to the rectifier output voltage; the transmitting end also includes a feedback control module; the feedback control module is used to receive the second harmonic reflected by the rectifier to obtain the output voltage of the receiving end, and adjust the signal transmitted by the signal source based on the output.

[0017] Preferably, the defective ground structure bandstop filter includes a ground layer, a dielectric substrate, and a microstrip line stacked from bottom to top. Both the top and bottom surfaces of the ground layer are etched with defective ground structures, and the bottom defective ground structure, in addition to having the same shape as the top defective ground structure, also has a wide transverse slot formed around its periphery. The varactor diode is connected across the wide transverse slot of the bottom defective ground structure.

[0018] Preferably, the defect ground structure on the top surface consists of four identical loop-shaped defect slots. The four loop-shaped defect slots are symmetrical along a first central axis and a second central axis, respectively, with the ends of the two loop-shaped defect slots symmetrical about the first central axis coinciding. The grounding layer surrounded by the loop-shaped defect slots on both sides of the second central axis is connected to both ends of the load via radio frequency chokes.

[0019] Preferably, the transverse wide grooves are respectively opened on the common side of the two loop-shaped defect grooves on the same side of the second central axis.

[0020] Preferably, the length of the microstrip line is equal to the length of the ground layer, and the microstrip line is symmetrical along the second central axis.

[0021] Preferably, the center frequency of the defective ground structure bandstop filter is twice the frequency of the signal source's transmitted signal.

[0022] Preferably, the rectifier includes a DC blocking capacitor C. block Matching capacitor C1, rectifier diode D1, matching inductor L1, and DC filter; the DC blocking capacitor C block One end of the filter is connected to the receiving antenna, and the other end is connected to the input of the defective ground structure band-stop filter; one end of the matching capacitor C1 is connected to the output of the defective ground structure band-stop filter, and the other end is connected to the ground terminal through the matching inductor L1; the rectifier diode D1 is connected in parallel with the matching capacitor C1, and the positive terminal of the rectifier diode D1 is connected to the matching inductor L1; the input terminal of the DC filter is connected to the negative terminal of the rectifier diode D1, and the output terminal is connected to the load.

[0023] Preferably, the DC filter includes an inductor L2 and a capacitor C2; one end of the inductor L2 is connected to the output terminal of the band-stop filter, and the other end is connected to the load; one end of the capacitor C2 is connected to the connection terminal between the inductor L2 and the load, and the other end is grounded.

[0024] Secondly, the present invention provides a wireless information transmission method based on a combined defective ground structure and harmonic reflection, which employs the aforementioned wireless information transmission system; the wireless information transmission method includes:

[0025] The signal source transmits a radio frequency signal with a frequency of f0 to the receiver through a transmitting antenna; after receiving the radio frequency signal, the receiving antenna transmits the radio frequency signal to the rectifier for rectification; the rectifier diode D1 in the rectifier transmits the output voltage of the rectifier by reflecting the second harmonic of the frequency 2f0 back to the transmitting end; the transmitting end adjusts the radio frequency signal transmitted to the receiving end according to the reflected output voltage, thereby controlling the wireless information transmission system.

[0026] Preferably, the method for obtaining the output voltage is as follows: the transmitter detects the second harmonic intensity reflected by the receiver through the feedback control module to obtain the second harmonic intensity dip frequency; and the output voltage of the rectifier is obtained according to the mapping relationship between the dip frequency and the output voltage.

[0027] The beneficial effects of this invention are:

[0028] 1. This invention utilizes the second harmonic generated by the rectifier diode itself as an information carrier, and indirectly obtains the output voltage information through the spectral characteristics (dimple frequency) in the reflected signal. There is no need to add feedback components such as voltage sampling chip and transmission line at the receiving end, thus avoiding the problems of complex structure and increased cost caused by traditional feedback circuits, and realizing a completely passive and non-contact voltage feedback mechanism.

[0029] 2. This invention utilizes the second harmonic generated by the nonlinear characteristics of diodes and combines it with the frequency-tunable characteristics of a defect-grounded band-stop filter. By detecting the second harmonic spectrum dip point reflected back to the transmitter, the system can infer the output voltage state in real time without interrupting information transmission. This method has a fast response and does not require interruption of communication or energy transmission.

[0030] 3. Simulation verification shows that, under a working frequency range of 900MHz-970MHz and a load of 1500Ω, the rectifier efficiency of this invention remains stable at 64%-68%. Furthermore, changes in output voltage have almost no impact on the rectifier efficiency, indicating that the introduction of the defective structure band-stop filter and the construction of the voltage feedback mechanism do not impair the core energy conversion function of the rectifier, effectively ensuring the stability and efficiency of the RF energy to DC energy conversion and reducing losses during energy transmission.

[0031] 4. The defective ground structure bandstop filter introduced in this invention is achieved by etching a specific pattern on the ground layer and combining it with a varactor diode. It has a compact structure, is easy to integrate with microstrip lines, and requires no complex additional circuitry. The entire feedback mechanism relies solely on existing rectifier diodes and the defective ground structure, greatly reducing hardware complexity and material costs, making it suitable for large-scale integration and applications. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a wireless power control method based on harmonic feedback.

[0033] Figure 2 This is a schematic diagram of an RFID closed-loop remote control wireless power supply system.

[0034] Figure 3 This is a SWIPT rectifier circuit diagram based on second harmonic communication.

[0035] Figure 4 This is a schematic diagram of the receiver in this invention.

[0036] Figure 5 This is the equivalent circuit diagram of the receiving end in this invention.

[0037] Figure 6 This is the top-level schematic diagram of the defective structure bandstop filter in this invention.

[0038] Figure 7 This is the underlying schematic diagram of the defective structure bandstop filter in this invention.

[0039] Figure 8 This is a flowchart of the process of the present invention.

[0040] Figure 9 This is the equivalent circuit diagram of frequency conversion in this invention.

[0041] Figure 10 This is a schematic diagram of the frequency response of the defect-ground structure bandstop filter under different output voltages in this invention.

[0042] Figure 11 This is a schematic diagram of the second harmonic intensity reflected under different output voltages in this invention.

[0043] Figure 12 This is a schematic diagram illustrating the relationship between the second harmonic dip frequency and the output voltage in this invention.

[0044] Figure 13 This is a schematic diagram illustrating the relationship between rectification efficiency and output voltage in this invention. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings.

[0046] like Figure 4 As shown, a wireless information transmission system combining defective ground structure and harmonic reflection includes a transmitter and a receiver. The transmitter includes a signal source, a feedback control module, and a transmitting antenna; the feedback control module is used to query the frequency of the second harmonic intensity dip point to obtain the output voltage of the receiver; the transmitting antenna is used to transmit radio frequency signals to the receiver. The receiver includes a receiving antenna, a rectifier, a DGS (defective ground structure) band-stop filter, and a load R. L The receiving antenna receives the radio frequency (RF) signal transmitted by the transmitting antenna and sends the RF signal to the rectifier for processing; the rectifier includes a DC blocking capacitor C. block Matching capacitor C1, rectifier diode D1, matching inductor L1, and DC filter. DC blocking capacitor C. block One end of the capacitor is connected to the receiving antenna, and the other end is connected to the input of the DGS band-stop filter. One end of the matching capacitor C1 is connected to the output of the band-stop filter, and the other end is connected to ground through the matching inductor L1. The rectifier diode D1 is connected in parallel with the matching capacitor C1, and the positive terminal of the rectifier diode D1 is connected to the matching inductor L1. The DC filter includes an inductor L2 and a capacitor C2; one end of the inductor L2 is connected to the output of the band-stop filter, and the other end is grounded through the capacitor C2. Load R L One end is connected to the junction of inductor L2 and capacitor C2, and the other end is connected to ground. The DGS band-stop filter is used to limit radio frequency signals with characteristic frequencies.

[0047] In this embodiment, the operating frequency of the wireless information transmission system is 900MHz; the DC blocking capacitor C block The capacitance of the capacitor is 22 pF; the capacitance of the matching capacitor C1 is 0.9 pF; the rectifier diode D1 is an HSMS2850; the inductance of the matching inductor L1 is 21 nH; the load R... L The resistance of the load is 1500Ω.

[0048] In traditional microstrip line structures, the distribution of radio frequency current follows the "skin effect": the fundamental (f0) and second harmonic (2f0) currents are mainly concentrated on the surface of the ground plane below the microstrip line. The current path is a vertical coupling of "microstrip line → dielectric substrate → ground plane" plus lateral flow on the ground plane surface. When a specific pattern (i.e., a defective ground structure) is etched into the ground plane, the lateral flow path of the current is blocked by the "defective trench," and the current must flow around the trench. The ground plane etching pattern changes the current distribution by "blocking the current path → introducing equivalent LC resonance." In microwave circuits, DGS (Difference Gauge Scheme) is often used to achieve band-stop or band-pass characteristics to suppress signals of specific frequencies. The equivalent circuit of a DGS band-stop filter is shown below. Figure 5 As shown, it is equivalent to a variable capacitor C connected in parallel. t Diode junction resistance R t and diode package inductor L t Variable capacitor C t The capacitance value varies with the output voltage of the rectifier.

[0049] like Figure 6 and Figure 7 As shown, the DGS bandstop filter includes a ground layer, a dielectric substrate, and a microstrip line stacked from bottom to top. The top surface of the ground layer is etched with a defective structure, which consists of four identical loop-shaped defect slots. The four loop-shaped defect slots are symmetrical along the first central axis ab and the second central axis cd, respectively, and the ends of the two loop-shaped defect slots symmetrical about the first central axis ab coincide.

[0050] The bottom surface of the ground layer is etched with a defect ground structure identical to that on the top surface. Furthermore, the ground layer, surrounded by loop-shaped defect grooves on both sides of the second central axis cd, is connected to the load R via RF chokes. LAt both ends of the structure, two transverse wide slots are formed on the common side of two loop-shaped defect slots located on the same side of the second central axis cd. Two varactor diodes D2 and D3 are respectively connected across these two transverse wide slots. Under different rectified output voltages, the equivalent capacitance of varactor diodes D2 and D3 changes, thereby changing the stopband center frequency of the DGS bandstop filter, making the center frequency of the bandstop filter near 2f0. Connecting the varactor diodes across the transverse wide slots ensures the highest electrical tuning efficiency and enhances tuning sensitivity. Secondly, connecting them to the "outer slot" means that the cathode pads and leads of the diodes can be connected more directly and shorter to the DC feed port, reducing series inductance. More importantly, it ensures that the tuning electric field of the two varactor diodes is mainly localized around the defect ground structure, reducing direct disturbance to the coupling region between the defect ground structures. The length of the microstrip line is equal to the length of the ground layer, and the microstrip line is symmetrical along the second central axis cd.

[0051] In this embodiment, varactor diodes D2 and D3 are selected as SMV1215.

[0052] The dimensions of the loop-shaped defect slot are the core parameters that determine the DGS band-stop filter, i.e., the variable capacitor C in the equivalent circuit. t The capacitance value and diode package inductance L t The inductance value determines the center frequency (2f0), stopband bandwidth, and suppression depth of the band-stop filter. Dimensional parameters need repeated optimization through electromagnetic simulations (such as HFSS) to stabilize the DGS stopband center frequency near the second harmonic (2f0) while ensuring low-loss transmission of the fundamental frequency (f0). The longer the longitudinal length of the loop-shaped defect slot (L1 / L2 / L3), the longer the current path, which is equivalent to introducing an additional series inductance into the ground plane (similar to the inductance effect of lengthening a wire). Therefore, the diode package inductance L... t The larger the inductance L, the lower the resonant frequency f0 (f0∝1 / L); the wider the transverse width of the groove (S1 / S2 / S3 / S4), the larger the overlap area between the microstrip line and the grounding layer at the edge of the groove. This is equivalent to the microstrip line and the grounding layer at the edge of the groove forming an additional parallel plate capacitor (the microstrip line is the upper plate, the grounding layer at the edge of the groove is the lower plate, and the dielectric substrate is the dielectric). Therefore, the variable capacitor C... t The larger the capacitance C, the lower the resonant frequency f0 (f0∝1 / C); the smaller the slot spacing (M1 / M2 / M3) of the loop-shaped defect groove, the lower the diode package inductance L. t and variable capacitor C t Coupling occurs, causing a shift in the total resonant frequency; a larger slot spacing (M1 / M2 / M3) narrows the stopband bandwidth. The wider the microstrip line, the greater the coupling capacitance with the ground plane, which enhances the variable capacitance C. tThe capacitance value C slightly reduces the resonant frequency and affects the characteristic impedance matching of signal transmission.

[0053] In this embodiment, the microstrip line is 50Ω; the dielectric substrate is RO4350 with a thickness of 0.762mm; L1=7.7mm, L2=1.8mm, L3=1.3mm; S1=0.3mm, S2=0.3mm, S3=0.5mm, S4=0.2mm; M1=8.5mm, M2=3mm, M3=7mm; L L =4.1mm, L s =1.6mm, L w =9.5mm.

[0054] like Figure 8 As shown, the working process of this wireless information transmission system is as follows:

[0055] The signal source transmits a radio frequency (RF) signal at frequency f0 to the receiver via a transmitting antenna; after receiving the RF signal, the receiving antenna transmits it to a rectifier for rectification. This process is repeated at different output voltages V. out Below, the stopband center frequency of the DGS bandstop filter shifts with changes in output voltage, and the center frequency shifts to the right as the output voltage increases, such as... Figure 9 As shown. Figure 10 As shown, the rectifier diode D1 in the rectifier is equivalent to a diode with an internal resistance of R. d The current is I 2f0 The current source; rectifier diode D1 at a bias voltage of V j Output current I under o It can be expressed using Taylor series expansion as follows:

[0056]

[0057] Among them, g k This represents the k-th order transconductance coefficient.

[0058] The second harmonic generated by rectifier diode D1 is used to transmit the rectified output voltage information. That is, when an RF signal with a frequency of f0 is transmitted at the transmitting end, rectifier diode D1 transmits the rectified output voltage information by reflecting the second harmonic with a frequency of 2f0 back to the transmitting end.

[0059] The transmitting end uses the output voltage to adjust the frequency of the reflected second harmonic dip to obtain the output voltage. For example... Figure 11 As shown, the second harmonic intensity dip point shifts under different output voltages, and the second harmonic intensity dip point shifts to the right as the output voltage increases; the frequency of this dip point has a continuous mapping relationship with the output voltage, as shown in the figure. Figure 12As shown, the transmitter performs spectrum analysis on the signal reflected from the receiver near 2f0. Specifically, the feedback control module detects the intensity of the second harmonic of the reflected signal and obtains the frequency of the second harmonic intensity dip, thereby determining the output voltage of the rectifier at that time. This enables feedback of the receiver's output voltage information.

[0060] In this embodiment, the frequency sweep range is 900MHz~970MHz.

[0061] The radio frequency signal transmitted by the transmitter is adjusted based on the output voltage feedback from the receiver, thereby controlling the wireless information transmission system. For example... Figure 13 As shown, the rectifier still has a rectification efficiency of 64%-68% at the operating frequency, and different output voltages have almost no effect on the rectification efficiency. It can be seen that the introduction of DGS and feedback has little impact on the original energy transmission function of the rectifier.

Claims

1. A wireless information transmission method based on combined defective ground structure and harmonic reflection, comprising a wireless information transmission system including a transmitter and a receiver; the transmitter including a signal source and a transmitting antenna; the receiver including a receiving antenna, a rectifier, and a load; characterized in that: The receiving end also includes a defective ground structure band-stop filter; a varactor diode is added to the defect slot of the defective ground structure band-stop filter; the varactor diode is used to adjust the equivalent capacitance of the defective ground structure band-stop filter according to the rectifier output voltage; the transmitting end also includes a feedback control module; the feedback control module is used to receive the second harmonic reflected by the rectifier to obtain the output voltage of the receiving end, and adjust the signal transmitted by the signal source based on the output. The wireless information transmission method includes: The signal source transmits a frequency of 1000 MHz to the receiver via a transmitting antenna. f 0 radio frequency signal; After receiving the radio frequency signal, the receiving antenna transmits the radio frequency signal to the rectifier for rectification; the rectifier diode D1 in the rectifier transmits the output voltage of the rectifier by reflecting the second harmonic of frequency 2f0 back to the transmitting end; the transmitting end adjusts the radio frequency signal transmitted to the receiving end according to the reflected output voltage, thereby controlling the wireless information transmission system; The method for obtaining the output voltage is as follows: the transmitting end performs frequency scanning of the transmitted signal within a set frequency range, and simultaneously performs spectrum analysis on the second harmonic signal reflected by the receiving end within the second harmonic range of the set frequency to obtain the second harmonic intensity dip frequency; based on the mapping relationship between the dip frequency and the output voltage, the output voltage of the rectifier is obtained.

2. The wireless information transmission method based on combined defective ground structure and harmonic reflection according to claim 1, characterized in that: The defective ground structure bandstop filter includes a ground layer, a dielectric substrate, and a microstrip line stacked from bottom to top; the top and bottom surfaces of the ground layer are both etched with defective ground structures, and the bottom defective ground structure, in addition to having the same shape as the top defective ground structure, also has a wide transverse slot on the periphery of the defective ground structure; the varactor diode is connected across the wide transverse slot of the bottom defective ground structure.

3. The wireless information transmission method based on combined defective ground structure and harmonic reflection according to claim 2, characterized in that: The defect ground structure on the top surface consists of four identical loop-shaped defect slots; the four loop-shaped defect slots are symmetrical along the first central axis and the second central axis, and the ends of the two loop-shaped defect slots symmetrical about the first central axis coincide; the ground layer surrounded by the loop-shaped defect slots on both sides of the second central axis is connected to both ends of the load through radio frequency chokes.

4. The wireless information transmission method based on combined defective ground structure and harmonic reflection according to claim 3, characterized in that: The transverse wide grooves are respectively opened on the common side of the two loop-shaped defect grooves on the same side of the second central axis.

5. The wireless information transmission method based on combined defective ground structure and harmonic reflection according to claim 2, characterized in that: The length of the microstrip line is equal to the length of the ground layer, and the microstrip line is symmetrical along the second central axis.

6. The wireless information transmission method based on combined defective ground structure and harmonic reflection according to claim 1, characterized in that: The center frequency of the defective ground structure bandstop filter is twice the frequency of the signal source's transmitted signal.

7. The wireless information transmission method based on combined defective ground structure and harmonic reflection according to claim 1, characterized in that: The rectifier includes a DC blocking capacitor C. block Matching capacitor C1, rectifier diode D1, matching inductor L1, and DC filter; the DC blocking capacitor C block One end of the filter is connected to the receiving antenna, and the other end is connected to the input of the defective ground structure band-stop filter; one end of the matching capacitor C1 is connected to the output of the defective ground structure band-stop filter, and the other end is connected to the ground terminal through the matching inductor L1; the rectifier diode D1 is connected in parallel with the matching capacitor C1, and the positive terminal of the rectifier diode D1 is connected to the matching inductor L1; the input terminal of the DC filter is connected to the negative terminal of the rectifier diode D1, and the output terminal is connected to the load.

8. The wireless information transmission method based on combined defective ground structure and harmonic reflection according to claim 7, characterized in that: The DC filter includes an inductor L2 and a capacitor C2; one end of the inductor L2 is connected to the output terminal of the band-stop filter, and the other end is connected to the load; one end of the capacitor C2 is connected to the connection terminal between the inductor L2 and the load, and the other end is grounded.

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