Target Object Detection Method Based on Microwave Photonic Radar and Active Phase-Modulated RFID Device

Abstract

The present invention provides a method for detecting a target object based on a microwave photon radar and an active phase modulation RFID device, which includes: the microwave photon radar system emits a leaky wave emission signal; after the antenna of the active phase modulation RFID device disposed on the target object receives the leaky wave emission signal, the active phase modulation RFID device controls the on / off state change of a switching device, makes the reflection coefficient of the active phase modulation RFID device be 1 when the switching device is turned on, and makes the reflection coefficient of the active phase modulation RFID device be -1 when the switching device is turned off, and the active phase modulation RFID device reflects the leaky wave emission signal to form a leaky wave reception signal; the microwave photon radar system receives the leaky wave reception signal reflected by the active phase modulation RFID device, and calculates the position of the target object by using the received leaky wave signal. The present invention can improve the modulation coefficient of the feedback signal received by the microwave photon radar system, thereby increasing the power of the leaky wave reception signal and improving the detection accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of object detection, and more specifically, to a method for detecting target objects based on a microwave photon radar and an active phase modulation RFID device. Background Art

[0002] With the development of detection technologies, the detection of moving objects has been widely applied in many fields. For example, radar systems are used to detect moving vehicles, airplanes, etc., to determine their positions and moving directions, and then to judge whether a vehicle has violated traffic regulations or whether an aircraft is flying along a prescribed route.

[0003] Existing methods for detecting moving objects usually involve a radar system sending a detection signal, typically a high-frequency radio signal. When the detection signal encounters a moving object, the moving object reflects the detection signal. The radar system then receives the reflected signal and calculates the distance between the target object and the radar system based on the transmitted signal and the reflected signal, and also calculates the moving direction of the target object.

[0004] However, since the signals reflected back by the target object are usually very weak, the radar system easily filters out these weak signals as interference signals, resulting in the radar system being unable to accurately detect moving objects. Some existing moving objects are equipped with RFID devices that reflect the detection signals transmitted by the radar system, thereby increasing the intensity of the reflected signals received by the radar system to improve the accuracy of detecting moving objects.

[0005] Chinese Patent Application Publication No. CN101436261A discloses a 2.45 GHz semi-active radio frequency identification tag. The radio frequency identification tag is provided with two dipole antennas, a load modulation module, and a dual-path selection module. The dual-path selection module is provided with two switches, and one of the switches can control the connection between the load modulation module and one of the dipole antennas. By changing the on / off state of the switch, the connection state between the dipole antennas and the load modulation module can be changed, thereby changing the reflection coefficient of the radio frequency identification tag. For example, when the switch is off, the load modulation module is disconnected from the dipole antenna, the load modulation module is not powered on, and the radio frequency signal received by the antenna module is completely reflected by the antenna module. At this time, the reflection coefficient is -1. When the switch is on, the load modulation module is electrically connected to the dipole antenna, the load modulation module is powered on, the radio frequency signal received by the antenna module is received by the load modulation module, and no radio frequency signal is transmitted by the antenna module. At this time, the reflection coefficient is 0.

[0006] Generally, the received power P of the reflected signal received by the microwave photon radar from the RFID device r can be calculated by the following formula:

[0007]

[0008] where P t is the signal transmission power of the radar system, G r is the receiving gain of the radar system, G t is the transmitting gain of the radar system, X is the degree of polarization mismatch, λ is the wavelength of the transmitted signal, r is the distance between the antenna and the target object, M is the modulation coefficient, B is the path blockage loss, F a is the attenuation margin. Therefore, in order to increase the received power P r , the transmission power P t , the receiving gain G r , the transmitting gain G t and the modulation coefficient M should be increased, and the path blockage loss B and the attenuation margin F a should be reduced. However, due to the power limitation of the radar system, the transmission power P t is often limited. The transmitting gain G r and the receiving gain G t can be increased by installing a directional antenna on the radar, but it will increase the production cost of the radar system. In fact, the received power P r can be improved by considering increasing the modulation coefficient M. The modulation coefficient M can be calculated by the following formula:

[0009]

[0010] where Γ A and Γ B are the reflection coefficients of the RFID device in two states respectively. In the prior art, the reflection coefficients of the RFID device are -1 and 0 respectively. Therefore, the value of the modulation coefficient M is 1 / 4. Since the value of the modulation coefficient M is small, it affects the power of the reflected signal received by the radar system and the accuracy of detecting moving objects. Summary of the Invention

[0011] The object of the present invention is to provide a method for detecting a target object based on a microwave photon radar and an active phase modulation RFID device, which can improve the power of the received signal of the radar system.

[0012] To achieve the above object, the object detection method based on a microwave photon radar and an active phase modulation RFID device provided by the present invention includes: the microwave photon radar system emits a leaky wave emission signal; after the antenna of the active phase modulation RFID device disposed on the target object receives the leaky wave emission signal, the active phase modulation RFID device controls the on / off state change of the switching device, making the reflection coefficient of the active phase modulation RFID device be 1 when the switching device is on, and making the reflection coefficient of the active phase modulation RFID device be -1 when the switching device is off. The active phase modulation RFID device reflects the leaky wave emission signal to form a leaky wave reception signal; the microwave photon radar system receives the leaky wave reception signal reflected by the active phase modulation RFID device and calculates the position of the target object by using the received leaky wave signal.

[0013] As can be seen from the above solution, since the reflection coefficients of the active phase modulation RFID device are 1 and -1 respectively when the switching device is in the on and off states, according to Formula 2, the modulation coefficient M is 1. Compared with the traditional RFID device, the active phase modulation RFID device used in the present invention can enable the radar system to receive a reflected signal with higher power. After the radar system receives the reflected signal with high power, it can calculate the position of the target object more accurately and avoid mis-filtering it as an interference signal due to the too small power of the received reflected signal.

[0014] A preferred solution is that when the active phase modulation RFID device receives the leaky wave emission signal, it controls the change of the on state of the switching device; when the active phase modulation RFID device does not receive the leaky wave emission signal, it stops controlling the change of the on state of the switching device.

[0015] Thus, it can be seen that only when the active phase modulation RFID device receives the leaky wave emission signal, the on / off state of the switching device is controlled to change, that is, the switching device is driven to act. When the leaky wave emission signal is not received, the switching device is stopped from being driven to work. On the one hand, it can avoid the switching device from being in the working state for a long time and extend the service life of the switching device. On the other hand, it can avoid high losses caused by driving the switching device to act for a long time.

[0016] A further solution is that the active phase modulation RFID device is provided with a low-frequency signal generating circuit, and the low-frequency signal generating circuit is used to output a low-frequency signal to the switching device to control the on / off state change of the switching device.

[0017] It can be seen that by setting the low-frequency signal generating circuit to output a low-frequency signal to control the operation of the switching device, it is ensured that the switching device works in the low-frequency state, and further ensures the accurate switching of the reflection coefficient of the active phase modulation RFID device.

[0018] A further solution is that when the active phase modulation RFID device receives the leaky wave emission signal, the low-frequency signal generation circuit outputs a low-frequency signal to the switching device; when the active phase modulation RFID device does not receive the leaky wave emission signal, the low-frequency signal generation circuit stops outputting the low-frequency signal to the switching device.

[0019] A further solution is that the switching device is a diode. The anode terminal of the diode receives the low-frequency signal. The low-frequency signal is a low-frequency pulse signal. When the low-frequency pulse signal is at a high level, the diode conducts; when the low-frequency pulse signal is at a low level, the diode cuts off.

[0020] Using a diode as the switching device makes the structure of the active phase modulation RFID device simple and the production cost relatively low. Moreover, the performance of the diode is stable, which can ensure that the switching device works for a long time.

[0021] A further solution is that the active phase modulation RFID device includes an inductor. The inductor is connected between the low-frequency signal generation circuit and the switching device, and the low-frequency signal is output to the switching device through the inductor.

[0022] Since the inductor allows the low-frequency signal to pass through while the high-frequency signal cannot pass through the inductor, by setting the inductor, it can ensure that the level signal passes through the inductor and controls the operation of the switching device, while the high-frequency signal received by the antenna cannot pass through the inductor, ensuring that the high-frequency signal does not affect the operation of the switching device.

[0023] A further solution is that the active phase modulation RFID device includes an antenna and a load resistor. The antenna, the load resistor and the switching device are connected in sequence. One end of the switching device is connected to the load resistor, and the second end of the switching device is grounded.

[0024] A further solution is that when the switching device conducts, the antenna is short-circuited to the ground, making the reflection coefficient of the active phase modulation RFID device 1; when the switching device cuts off, the antenna is open-circuited, making the reflection coefficient of the active phase modulation RFID device -1.

[0025] It can be seen that when the switching device conducts, since the load resistor is directly grounded, it is equivalent to the antenna being directly grounded, and the antenna and the load are mismatched, making the reflection coefficient of the active phase modulation RFID device 1. When the switching device cuts off, the antenna and the load resistor do not form a loop, and no current flows through the load resistor. The signal received by the active phase modulation RFID device is all reflected, and its reflection coefficient is -1. Since the reflection coefficient of the active phase modulation RFID device switches between 1 and -1, it is equivalent to forming signals with opposite phases.

[0026] A further solution is that after the microwave photon radar system receives the leaky wave reception signal, it calculates the position of the target object according to the time difference between the emission time of the leaky wave emission signal and the reception time of the leaky wave reception signal.

[0027] It can be seen that when calculating the position of the target object, only the time difference between the emission time of the leaky wave emission signal and the reception time of the leaky wave reception signal and the wavelength of the leaky wave emission signal need to be obtained. The calculation of the distance of the target object is very simple and does not require very complex calculations, which can improve the detection efficiency.

[0028] A further solution is that after the microwave photon radar system receives the leaky wave reception signal, the moving direction of the target object is calculated according to the frequency difference between the leaky wave emission signal and the leaky wave reception signal.

[0029] It can be seen that the application of the Doppler effect can quickly calculate the moving direction of the target object, and the calculation is very simple. Brief Description of the Drawings

[0030] Figure 1 is a structural block diagram of the microwave photon radar system and the active phase modulation RFID device used in the embodiment of the method for detecting a target object based on the microwave photon radar and the active phase modulation RFID device of the present invention.

[0031] Figure 2 is a flowchart of the embodiment of the method for detecting a target object based on the microwave photon radar and the active phase modulation RFID device of the present invention.

[0032] Figure 3 is a flowchart of calculating the position and moving direction of the target object in the embodiment of the method for detecting a target object based on the microwave photon radar and the active phase modulation RFID device of the present invention.

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments. Detailed Embodiments

[0034] The method for detecting a target object based on the microwave photon radar and the active phase modulation RFID device of the present invention uses the microwave photon radar to emit signals, sets an active phase modulation RFID device on the target object, reflects the received signals by using the active phase modulation RFID device, and calculates the position, moving direction and even moving speed of the target object by using the reflected signals. Preferably, the target object is a high-speed moving object, such as an airplane, a car, etc.

[0035] See Figure 1, the microwave photon radar system used in the present invention includes a leaky wave transmitting antenna 11 and a leaky wave receiving antenna 12. The leaky wave transmitting antenna 11 is used to transmit a leaky wave transmission signal. Preferably, the leaky wave transmission signal 11 is a high-frequency radio signal, such as a 24 GHz wireless signal. After the leaky wave transmission signal encounters the target object to be detected, it is reflected by the target object to form a leaky wave reception signal, and the leaky wave receiving antenna 12 receives this leaky wave reception signal. The microwave photon radar system 10 can also be provided with a processor for calculating parameters such as the position, moving direction, and moving speed of the target object according to the leaky wave transmission signal and the leaky wave reception signal. Of course, the microwave photon radar system 10 can also be provided with devices such as a signal amplifier and a filter for performing signal amplification, filtering, etc. on the received leaky wave reception signal, especially removing the low-frequency signals in the received signal to ensure the accuracy of the calculation results.

[0036] In practical applications, the leaky wave transmitting antenna 11 and the leaky wave receiving antenna 12 of the microwave photon radar system 10 can be integrated in the same antenna module, or implemented by the same antenna, that is, using the same antenna to both transmit the leaky wave transmission signal and receive the leaky wave reception signal.

[0037] The active phase modulation RFID device 20 used in this embodiment includes an antenna 21, a load resistor R1, an inductor L1, a diode D1 as a switching device, and a filter capacitor C1. A low-frequency signal source 25 and a Schmitt trigger 26 are also provided. Among them, the low-frequency signal source 25 and the Schmitt trigger 26 form a low-frequency signal generation circuit for generating a low-frequency signal.

[0038] The low-frequency signal source 25 is a signal source for generating a low-frequency sine wave, which is realized by using an oscillation circuit, for example. The frequency of the generated low-frequency sine wave signal can be 1 kHz. The frequency of the low-frequency sine wave signal is very low compared to the frequency of the leaky wave transmission signal, so it becomes a low-frequency sine wave signal. The Schmitt trigger 26 receives the low-frequency sine signal output by the low-frequency signal source 25 and shapes the low-frequency sine information to form a low-frequency pulse signal. In an ideal state, the duty cycle of the low-frequency pulse signal is 50%, that is, the duration of the high level is equal to the duration of the low level. And the Schmitt trigger 26 does not change the frequency of the low-frequency sine wave signal. Therefore, the frequency of the low-frequency pulse signal is equal to the frequency of the low-frequency sine wave signal. In this embodiment, the low-frequency signal output by the low-frequency signal generation circuit is the low-frequency pulse signal output by the Schmitt trigger 26.

[0039] The antenna 21 is used to receive the leaky-wave reception signal transmitted by the leaky-wave transmitting antenna 11, and can reflect the received leaky-wave transmitting signal back to form a leaky-wave reception signal. The antenna 21 is connected to the first end of the load resistor R1, the second end of the load resistor R1 is connected to the diode D1, the anode end of the diode D1 is connected to the load resistor R1, and the cathode end is grounded.

[0040] An inductor L1 is connected between the Schmidt trigger 26 and the anode end of the diode D1. One end of the inductor L1 is connected between the anode of the diode D1 and the load resistor R1. In this way, the low-frequency pulse signal output by the Schmidt trigger 26 will be output to the anode end of the diode D1 through the inductor L1. In this embodiment, the diode is a PIN diode, and its conduction voltage drop is usually about 0.7 volts. In order to drive the change of the on-off state of the diode D1, the high level and the low level of the low-frequency pulse signal output by the Schmidt trigger 26 should be higher and lower than the conduction voltage drop of the diode D1 respectively. For example, the high level of the low-frequency pulse signal can be 3 volts, and the low level can be 0.2 volts. In this way, when the low-frequency pulse signal is at a high level, the diode D1 is forward-biased and in the on state. When the low-frequency pulse signal is at a low level, the diode D1 is not conducting, that is, in the off state.

[0041] From Figure 1 It can be seen that when the diode D1 is in the on state, the antenna 21, the load resistor R1, and the diode D1 form a loop. Since the load resistor R1 is actually grounded, therefore, the load resistor R1 is equivalent to a short circuit to the ground, that is, the antenna 21 is also short-circuited to the ground. It can be considered that the load resistor connected to the antenna 21 is infinite at this time. The reflection coefficient Γ of the active phase-modulated RFID device 20 can be calculated by the following formula:

[0042]

[0043] Where Z L is the input impedance in the circuit connected to the antenna 21, and Z * ANT is the input impedance of the antenna 21. When the diode D1 is in the on state, since the load resistor R1 is grounded, therefore, in the circuit forming a loop with the antenna 21, the input impedance Z L can be considered infinite, and the input impedance Z * ANT of the antenna 21 is usually a few tens of ohms. Therefore, it can be understood that the input impedance Z * ANT of the antenna 21 is much smaller than the input impedance Z L . Therefore, according to Equation 3, when the diode D1 is in the on state, the reflection coefficient Γ of the active phase-modulated RFID device 20 is 1.

[0044] When the diode D1 is in the cut-off state, a loop cannot be formed among the antenna 21, the load resistor R1, and the diode D1. Moreover, since the inductor L1 does not allow high-frequency signals to pass through, the high-frequency leakage emission signal received by the antenna 21 cannot pass through the inductor L1, and thus a loop cannot be formed. In this way, no current flows through the load resistor R1, and the input impedance Z in the circuit connected to the antenna 21 can be considered L to be 0. According to Equation 3, when the diode D1 is in the cut-off state, the reflection coefficient Γ of the active phase modulation RFID device 20 is -1.

[0045] It can be seen that when the on-off state of the diode D1 changes, the reflection coefficient Γ of the active phase modulation RFID device 20 varies between 1 and -1. According to Equation 2, the modulation coefficient M of the active phase modulation RFID device 20 is 1. Compared with the traditional RFID device, the modulation coefficient M of the active phase modulation RFID device 20 used in this embodiment is four times that of the traditional RFID device. According to Equation 1, the power of the reflected signal received by the leakage wave receiving antenna 12 of the microwave photon radar system 20 will increase significantly, thereby improving the accuracy of subsequent calculations. In addition, since the power of the reflected signal received by the leakage wave receiving antenna 12 is relatively large, the amplification factor of the microwave photon radar system 20 for the received leakage wave receiving signal can be reduced, which is beneficial to reducing the complexity of the microwave photon radar system 20 and can reduce the production cost of the microwave photon radar system 20.

[0046] In the active phase modulation RFID device 20, a filter capacitor C1 is also connected between the output terminal of the Schmidt trigger 26 and the inductor L1. One end of the filter capacitor C1 is connected to the inductor L1, and the other end is grounded. The filter capacitor C1 can filter out the interference signals of the low-frequency pulse signals output by the Schmidt trigger 26, making the waveform of the low-frequency pulse signals input to the diode D1 more regular.

[0047] It can be understood that since the reflection coefficients of the active phase modulation RFID device 20 for the received leakage wave receiving signals are 1 and -1 respectively, the active phase modulation RFID device 20 is equivalent to performing binary phase modulation (BPM) on the received leakage wave emission signals, and a 180° phase difference is formed between the reflected leakage wave receiving signals in the two states. Assume that in the first state, the leakage wave receiving signal M1(t) is expressed by the following formula:

[0048] M1(t) = S(t) * cos(2πft + Φ0) (Equation 4)

[0049] where S(t) is the received leakage wave receiving signal, f is the frequency of the leakage wave receiving signal, and Φ0 is the initial phase angle.

[0050] Then, in the second state, the leaked-wave received signal M2(t) is expressed by the following formula:

[0051] M2(t) = S(t) * cos(2πft + Φ0 + π) (Equation 5)

[0052] The following combines Figure 2 to introduce the process of the microwave photon radar system 10 using the active phase modulation RFID device 20 to detect a target object. First, the microwave photon radar system 10 executes step S1 to send a leaked-wave transmission signal through the leaked-wave transmitting antenna. The transmitted leaked-wave transmission signal is a ultra-high frequency wireless signal. Then, the active phase modulation RFID device 20 executes step S2 to determine whether it has received the leaked-wave transmission signal. If it has received the leaked-wave transmission signal, it executes step S3 to output a low-frequency sine wave signal from the low-frequency signal source 25 and output a low-frequency pulse signal from the Schmitt trigger 26.

[0053] If it has not received the leaked-wave transmission signal, it executes step S7, and the low-frequency signal source 25 does not output a low-frequency sine wave signal. For example, a circuit for detecting the current of the antenna 21 is provided in the active phase modulation RFID device 20. If there is a current in the antenna 21, it indicates that the leaked-wave transmission signal has been received, and the low-frequency signal source 25 is controlled to start working accordingly; when there is no current in the antenna 21, it indicates that the leaked-wave transmission signal has not been received, and the low-frequency signal source 25 is controlled to stop working accordingly to prevent the diode D1 from being in the switching state for a long time. Then, it returns to execute step S2 to continue determining whether the leaked-wave transmission signal has been received.

[0054] After the low-frequency signal generation circuit outputs a low-frequency signal, it executes step S4 to drive the on-off state change of the diode D1 as a switching device. When the switching state of the diode D1 changes, the reflection coefficient of the active phase modulation RFID device 20 changes between 1 and -1, and the antenna 21 reflects the received signal, but the phase difference is 180°. The signal reflected by the antenna 21 forms a leaked-wave received signal, and the leaked-wave receiving antenna 12 receives the leaked-wave received signal, that is, it executes step S5. Finally, the microwave photon radar system 10 executes step S6 to calculate parameters such as the position of the target object using the received microwave received signal.

[0055] See Figure 3, when the microwave photon radar system 10 calculates parameters such as the position of the target object, it first executes step S11 to record the emission time t1 and emission frequency f1 of the leaky wave emission signal. Then, it executes step S12, and when the leaky wave reception signal is received, it records the reception time t2 and emission frequency f2 of the leaky wave reception signal. Then, it executes step S13 to calculate the time difference between the emission time t1 of the leaky wave emission signal and the reception time t2 of the leaky wave reception signal, and uses this time difference and the wavelength of the leaky wave emission signal to calculate the distance between the target object and the microwave photon radar system, that is, it executes step S14.

[0056] Then, it executes step S15 to calculate the frequency difference between the emission frequency f1 of the leaky wave emission signal and the reception frequency f2 of the leaky wave reception signal. Finally, it executes step S16. According to this frequency difference, it applies the Doppler principle to calculate the moving direction of the target object. If the emission frequency f1 of the leaky wave emission signal is greater than the reception frequency f2 of the leaky wave reception signal, it means that the target object is moving away from the microwave photon radar system. If the emission frequency f1 of the leaky wave emission signal is less than the reception frequency f2 of the leaky wave reception signal, it means that the target object is moving towards the microwave photon radar system. In addition, the radial moving speed of the target object can also be calculated based on this frequency difference, and then the linear speed of the target object can be calculated.

[0057] The present invention improves the active phase modulation RFID device 20, making the reflection coefficient of the active phase modulation RFID device 20 vary between 1 and -1, increasing the modulation coefficient M, thereby increasing the power of the leaky wave reception signal, enabling the microwave photon radar system to more accurately calculate parameters such as the position, moving direction, and moving speed of the target object.

[0058] Finally, it should be emphasized that the above is only the preferred embodiment of the present invention and is not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for detecting a target object based on a microwave photon radar and an active phase modulation RFID device, characterized in that, Including: The microwave photon radar system emits a leaky wave emission signal; After the antenna of the active phase modulation RFID device disposed on the target object receives the leaky wave emission signal, the active phase modulation RFID device controls the change of the on-off state of the switching device. When the switching device is turned on, the reflection coefficient of the active phase modulation RFID device is 1, and when the switching device is turned off, the reflection coefficient of the active phase modulation RFID device is -1. The active phase modulation RFID device reflects the leaky wave emission signal to form a leaky wave reception signal; The microwave photon radar system receives the leaky wave reception signal reflected by the active phase modulation RFID device, and calculates the position of the target object by using the leaky wave reception signal. The active phase modulation RFID device includes an antenna and a load resistor. The antenna, the load resistor and the switching device are connected in sequence. One end of the switching device is connected to the load resistor, and the second end of the switching device is grounded; When the switching device is turned on, the antenna is short-circuited to the ground, so that the reflection coefficient of the active phase modulation RFID device is 1; When the switching device is turned off, the antenna is open, so that the reflection coefficient of the active phase modulation RFID device is -1.

2. The method for detecting a target object based on a microwave photon radar and an active phase modulation RFID device according to claim 1, wherein: When the active phase modulation RFID device receives the leaky wave emission signal, it controls the change of the on state of the switching device; When the active phase modulation RFID device does not receive the leaky wave emission signal, it stops controlling the change of the on state of the switching device.

3. The method for detecting a target object based on a microwave photon radar and an active phase modulation RFID device according to claim 2, wherein: The active phase modulation RFID device is provided with a low-frequency signal generating circuit, and the low-frequency signal generating circuit is used to output a low-frequency signal to the switching device to control the change of the on-off state of the switching device.

4. The method for detecting a target object based on a microwave photon radar and an active phase modulation RFID device according to claim 3, wherein: When the active phase modulation RFID device receives the leaky wave emission signal, the low-frequency signal generating circuit outputs the low-frequency signal to the switching device; When the active phase modulation RFID device does not receive the leaky wave emission signal, the low-frequency signal generating circuit stops outputting the low-frequency signal to the switching device.

5. The method for detecting a target object based on a microwave photon radar and an active phase modulation RFID device according to claim 3 or 4, wherein: The switching device is a diode. The anode terminal of the diode receives the low-frequency signal. The low-frequency signal is a low-frequency pulse signal. When the low-frequency pulse signal is at a high level, the diode is turned on. When the low-frequency pulse signal is at a low level, the diode is turned off.

6. The method for detecting a target object based on a microwave photon radar and an active phase modulation RFID device according to claim 3 or 4, wherein: The active phase modulation RFID device includes an inductor, and the inductor is connected between the low-frequency signal generation circuit and the switching device, and the low-frequency signal is output to the switching device through the inductor.

7. The method for detecting a target object based on a microwave photon radar and an active phase modulation RFID device according to any one of claims 1 to 4, characterized in that: After the microwave photon radar system receives the leaky wave reception signal, the position of the target object is calculated according to the time difference between the transmission time of the leaky wave transmission signal and the reception time of the leaky wave reception signal.

8. The method for detecting a target object based on a microwave photon radar and an active phase modulation RFID device according to any one of claims 1 to 4, characterized in that: After the microwave photon radar system receives the leaky wave reception signal, the moving direction of the target object is calculated according to the frequency difference between the leaky wave transmission signal and the leaky wave reception signal.

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