Microstrip mixer and Doppler microwave detection module

Abstract

The present invention provides a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the microstrip mixer comprises an electric bridge, wherein the impedance characteristic of the electric bridge is maintained in a state by suppressing the transient change of an electrical signal in the electric bridge, thereby ensuring the impedance matching design of the microstrip mixer and improving the frequency selection characteristic of the microstrip mixer, correspondingly the microstrip mixer only presents a lower loss and a narrowed bandwidth in the working frequency band, and the frequency selection characteristic of the microstrip mixer is excellent and can ensure the output power and anti-interference performance of the Doppler intermediate frequency signal, thereby facilitating the improvement of the detection accuracy of the Doppler microwave detection module for the movement of objects in the corresponding detection space.

Description

Technical Field

[0001] The invention relates to the field of Doppler microwave detection, in particular to a microstrip mixer and a Doppler microwave detection module with the microstrip mixer. Background Art

[0002] With the development of Internet of Things technology, artificial intelligence, smart home, and smart security technology have higher and higher requirements for environmental detection, especially for the detection accuracy of human presence, movement, and micro-motion characteristics. Only by obtaining sufficiently stable detection results can we provide accurate judgment basis for smart terminal devices. Among them, radio technology, including microwave detection technology based on the principle of Doppler effect, as an important hub connecting people and objects, and objects and objects, has unique advantages in behavior detection and existence detection technology. It can detect active objects, such as human motion characteristics, movement characteristics, and micro-motion characteristics, and even human heartbeat and breathing characteristics without infringing on human privacy, and therefore has broad application prospects.

[0003] Specifically, the Doppler microwave detection module of the prior art is fed by a local oscillator signal through a mixer to transmit a detection beam corresponding to the frequency of the local oscillator signal in the corresponding detection space, and receives an echo formed by the detection beam being reflected by at least one object in the detection space to receive a feedback signal, wherein the mixer receives the feedback signal and outputs a Doppler intermediate frequency signal corresponding to the frequency difference between the local oscillator signal and the feedback signal in a mixing and detection manner. Based on the principle of the Doppler effect, the fluctuation in amplitude of the Doppler intermediate frequency signal theoretically corresponds to the movement of the object in the detection space. In order to ensure the feedback accuracy of the Doppler intermediate frequency signal on the movement of the object in the detection space, based on the advantages of the existing balanced mixer with low noise and high sensitivity, the mixer of the Doppler microwave detection module of the prior art mainly adopts a balanced mixer. Please refer to the drawings of the specification of the present invention for details. Figure 1 and Figure 2As shown, the equivalent circuit principle of the existing balanced mixer and a microstrip balanced mixer using a two-branch 3dB bridge based on the equivalent circuit principle are respectively illustrated, wherein the balanced mixer includes a ring bridge 10P, two mixing tubes 20P and an intermediate frequency output port 30P, wherein the ring bridge 10P has a local oscillator signal input port 101P, a feedback signal input port 102P, a first mixing port 103P, a second mixing port 104P, a first microstrip arm 11P connected between the local oscillator signal input port 101P and the feedback signal input port 102P, and a first microstrip arm 11P connected to the local oscillator signal input port 101P and the feedback signal input port 102P. a second microstrip arm 12P between the feedback signal input port 102P and the first mixing port 103P, a third microstrip arm 13P connected between the first mixing port 103P and the second mixing port 104P, and a fourth microstrip arm 14P connected between the second mixing port 104P and the local oscillator signal input port 101P, wherein the local oscillator signal input port 101P, the feedback signal input port 102P, the first mixing port 103P and the second mixing port 104P are sequentially arranged in a circular direction to form the first microstrip arm 11P, the third microstrip arm 13P connected between the first mixing port 103P and the second mixing port 104P, and the fourth microstrip arm 14P connected between the second mixing port 104P and the local oscillator signal input port 101P. The microstrip frame structure of the second microstrip arm 12P, the third microstrip arm 13P and the fourth microstrip arm 14P are connected end to end, wherein the two ends with different polarities of the two mixing tubes 20P belonging to different mixing tubes 20P are respectively connected to the first mixing port 103P and the second mixing port 104P, and the other two ends with different polarities of the two mixing tubes 20P belonging to different mixing tubes 20P are connected to the same ground capacitor to ensure that the two ends are short-circuited to the ground at high frequency, corresponding to the two ends of the two mixing tubes 20P that are grounded and electrically connected to the intermediate frequency output port 30P. state, forming a high-frequency filtering for the intermediate frequency output port 30P, so that the power of the local oscillator signal and the feedback signal respectively input from the local oscillator signal input port 101P and the feedback signal input port 102P can be fully loaded on the two mixing tubes 30P without leaking to the intermediate frequency output port 30P, wherein the grounded ends of the two mixing tubes 20P are electrically connected to the intermediate frequency output port 30P through two microstrip connecting lines 31P of equal electrical length, which is beneficial to the cancellation of the noise current in the Doppler intermediate frequency signal, and thus the corresponding balanced mixer presents the advantages of low noise and high sensitivity.

[0004] In particular, based on the equivalent circuit principle of the balanced mixer, the structure of the balanced mixer has a variety of variations, the main difference being the structural variation of the ring bridge 10P. Specifically, referring to the accompanying drawings of the specification of the present invention, Figures 3 to 10 As shown, different structures of the ring bridge 10P are schematically shown, wherein Figures 3 to 9The typical two-branch bridge, three-branch bridge, variable resistance bridge, ring two-branch variable resistance bridge, ring bridge, broadband ring bridge, 180° hybrid ring bridge are shown respectively. Figures 3 to 9 The illustrated embodiments of the ring bridge 10P are different embodiments or combined embodiments. The specific embodiments of the ring bridge 10P are flexible and varied. Figures 3 to 9 The illustrated variations or combined variations of different embodiments of the annular bridge 10P correspond to Fig.10 , a structure of a balanced mixer applied to the existing Doppler microwave detection module is shown. Although the specific implementation of the ring bridge 10P is flexible and changeable, the corresponding equivalent circuit structure does not deviate from Figure 1 The equivalent circuit principle shown in the figure, the anti-interference ability of the corresponding balanced mixer under the condition of satisfying impedance matching still needs to be improved. Fig.12 As shown, based on Fig.10 The structure of the balanced mixer is shown in FIG. 1 , and an impedance matching design example of the balanced mixer is performed at an operating frequency of 5.8 GHz in the ISM band. The frequency selection characteristic diagram and anti-interference test diagram of the balanced mixer under the condition of satisfying impedance matching are shown in FIG. Fig.11 Based on the characterization of the reflection coefficients of the local oscillator signal input port 101P and the feedback signal input port 102P by the S11 curve and the S22 curve, the loss of the balanced mixer at the 5.8GHz frequency point is significantly reduced and presents a frequency selection characteristic. However, on the one hand, the loss of the balanced mixer at the 5.8GHz frequency point is only less than -10dB, which is not ideal (generally required to be less than -20dB) and it is difficult to ensure the output signal strength of the Doppler intermediate frequency signal. On the other hand, the loss of the balanced mixer in the frequency range below 3GHz is still less than -5dB and it is difficult to resist the electromagnetic radiation interference in the frequency range below 3GHz. Therefore, it is difficult to ensure the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the detection space in today's increasingly complex electromagnetic environment. Specifically corresponding to Fig.12 , based on the interference test of the interference signal in the frequency range of 80MHz to 6GHz (corresponding to the frequency range specified in the radiation immunity test of the latest standard IEC 61000-4-3 / GB T 17626.3) transmitted dynamically to the Doppler intermediate frequency signal output by the balanced mixer, in which the Doppler intermediate frequency signal under the interference signal of a certain frequency is screenshotted, and the amplitude change of the interference of the interference signal of this frequency range on the balanced mixer caused by the Doppler intermediate frequency signal even exceeds 54.4mV. Summary of the invention

[0005] One object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the S11 curve and the S22 curve of the microstrip mixer show obvious narrow troughs in the working frequency band corresponding to the corresponding local oscillator signal frequency, and the microstrip mixer has lower loss and narrowed bandwidth in the working frequency band, and the microstrip mixer has excellent frequency selection characteristics in the working frequency band and can ensure the output signal strength of the corresponding Doppler intermediate frequency signal.

[0006] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the S11 curve and the S22 curve of the microstrip mixer tend to be flat and have higher losses in the non-working frequency band, that is, the S11 curve and the S22 curve of the microstrip mixer only show obvious narrow troughs in the working frequency band, and the microstrip mixer has lower losses and narrowed bandwidth only in the working frequency band. The corresponding frequency selection characteristics of the microstrip mixer are excellent and can ensure the output signal strength and anti-interference performance of the Doppler intermediate frequency signal, which is beneficial to improve the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0007] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space is improved, and the corresponding Doppler microwave detection module is suitable for combined detection of action characteristics including human body movement, micro-movement, breathing and heartbeat.

[0008] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the microstrip mixer has lower loss and narrowed bandwidth only in the working frequency band, and the radiation immunity test based on the IEC 61000-4-3 / GB T 17626.3 standard will not produce amplitude changes in the Doppler intermediate frequency signal that exceed the standard limit. Accordingly, the Doppler microwave detection module can pass the radiation immunity test of the IEC 61000-4-3 / GB T 17626.3 standard, which is conducive to the promotion of the Doppler microwave detection module and the improvement of commercial competitiveness in the field of Doppler microwave detection.

[0009] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the microstrip mixer includes a bridge, wherein the impedance characteristics of the bridge are maintained by suppressing transient changes of electrical signals in the bridge, thereby ensuring the impedance matching design of the microstrip mixer and improving the frequency selection characteristics of the microstrip mixer, corresponding to the microstrip mixer presenting lower loss and narrowed bandwidth only in the working frequency band.

[0010] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the transient of the electrical signal in the bridge is suppressed, and the requirements of the bridge on the high-frequency and low-loss characteristics of its carrier are reduced, and accordingly the bridge is suitable for being carried by an ordinary circuit board substrate, which is beneficial to reduce the cost of the Doppler microwave detection module and simplify the production process of the Doppler microwave detection module by avoiding the use of a microwave-specific circuit board substrate with high-frequency and low-loss characteristics.

[0011] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the bridge includes a current suppression element arranged in the form of a component and a microstrip mixer line arranged in the form of a microstrip line and connected between the two ends of the current suppression element, wherein the current suppression element is arranged in the form of a resistor element or a high-frequency inductor element and has a transient suppression characteristic for an electrical signal, and is different from the resistance or inductance characteristics of the microstrip mixer line in the form of a microstrip line under the action of a high-frequency electrical signal and can maintain the impedance characteristics of the bridge and the impedance characteristics of the microstrip mixer line under the action of a high-frequency local oscillator signal in a state of matching. In this way, by connecting the current suppression element between the two ends of the microstrip mixer line, the transient electrical signal in the bridge is suppressed while maintaining the impedance characteristics of the bridge, correspondingly, while ensuring the impedance matching design of the microstrip mixer, the frequency selection characteristics of the microstrip mixer are improved.

[0012] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein when the current suppression element is set to the state of the resistance element, the resistance element preferably adopts a zero-ohm resistance element to suppress the transient electrical signal in the bridge while avoiding the change of the impedance characteristics of the bridge, thereby further facilitating the impedance characteristics of the bridge to match the impedance characteristics of the microstrip mixer line under the action of the high-frequency local oscillator signal.

[0013] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the microstrip mixer further comprises two mixing tubes and an intermediate frequency output port located at the microstrip mixing line, wherein the microstrip mixing line has a first mixing port, a local oscillator signal input port suitable for local oscillator signal input, a feedback signal input port suitable for local oscillator signal output and feedback signal input, and a second mixing port in sequence from one end thereof, and the microstrip mixing line has a first microstrip mixing arm defined between the end and the first mixing port, a second microstrip mixing arm defined between the first mixing port and the local oscillator signal input port, a third microstrip mixing arm defined between the local oscillator signal input port and the feedback signal input port, a fourth microstrip mixing arm defined between the feedback signal input port and the second mixing port, and a fifth microstrip mixing arm defined between the second mixing port and the other end, so that the two ends of the current suppression element are respectively connected to the microstrip mixing line in a state where the current suppression element is connected to the two ends of the microstrip mixing line. The first microstrip mixing arm is connected to the first mixing port and connected to the second mixing port via the fifth microstrip mixing arm, wherein the second microstrip mixing arm and the fourth microstrip mixing arm have equal electrical lengths, and the third microstrip mixing arm has an electrical length greater than or equal to one eighth of a wavelength and less than or equal to one half of a wavelength, wherein two ends with different polarities belonging to different mixing tubes in the two mixing tubes are respectively connected to the first mixing port and the second mixing port, and the other two ends with different polarities belonging to different mixing tubes in the two mixing tubes are grounded to ensure that the two ends are short-circuited to the ground at high frequency, and a high-frequency filtering circuit consisting of a line grounded through one of the mixing tubes at the first mixing port and a line grounded through the other mixing tube at the second mixing port is formed between the first mixing port and the second mixing port, so that the power of the local oscillator signal and the feedback signal respectively input from the local oscillator signal input port and the feedback signal input port can be fully loaded on the two mixing tubes without leaking to the intermediate frequency output port.

[0014] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the first microstrip mixing arm and the fifth microstrip mixing arm have equal electrical lengths, and the corresponding connections between the first mixing port and the second mixing port and the current suppression element have equal electrical lengths, so as to be beneficial to the cancellation of the noise current in the Doppler intermediate frequency signal and to remove the position limitation of the intermediate frequency output port on the microstrip mixing line. The corresponding wiring methods of the microstrip mixer are diverse and can adapt to different line layout requirements, and at the same time are beneficial to improve the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0015] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein two ends of the two mixing tubes with different polarities belonging to different mixing tubes are respectively connected to the first mixing port and the second mixing port with equal electrical lengths, so that when the two ends are respectively connected to the first mixing port and the second mixing port, it is ensured that the connection between the first mixing port and the second mixing port and the current suppression element has equal electrical length, which is beneficial to ensure the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0016] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the two ends with different polarities belonging to different mixing tubes in the two mixing tubes are respectively connected to the first mixing port in a manner of being connected to the first microstrip mixing arm and are connected to the second mixing port in a manner of being connected to the fifth microstrip mixing arm, thereby simplifying the structural design of the microstrip mixer.

[0017] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the intermediate frequency output port is preferably located in the middle position of the third microstrip mixing arm, and the two sections on the third microstrip mixing arm bounded by the intermediate frequency output port have equal electrical lengths, thereby avoiding the influence of the non-equal electrical length connection between the first mixing port and the second mixing port and the current suppression element on the Doppler intermediate frequency signal caused by errors generated in the production process of the microstrip mixing line and the assembly process of the current suppression element and the mixing tube. Correspondingly, while ensuring the feedback accuracy of the Doppler intermediate frequency signal to the movement of objects in the corresponding detection space, the accuracy requirements for the production process of the microstrip mixing line and the assembly process of the current suppression element and the mixing tube are reduced, thereby being simple, easy to implement and low-cost.

[0018] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the connection line between the two mixing tubes and the first mixing port and the second mixing port is located in the area defined by the sequential connection of the local oscillator signal input port, the first mixing port, the second mixing port and the feedback signal input port, so as to reduce the space size occupied by the microstrip mixer and increase the angular mutation amount of the connection line between the two mixing tubes and the first mixing port and the second mixing port relative to the second microstrip mixing arm and the fourth microstrip mixing arm in the extension direction, thereby facilitating the maintenance of the impedance characteristics of the microstrip mixing line, and further suppressing the transient electrical signal in the bridge in parallel with the current suppression element, thereby correspondingly ensuring the feedback accuracy of the Doppler intermediate frequency signal to the movement of the object in the corresponding detection space.

[0019] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein at least one metal patch is connected to the high-frequency filter circuit so as to improve the high-frequency filtering characteristics of the high-frequency filter circuit by forming a distributed capacitance with the ground, thereby correspondingly improving the frequency selection characteristics of the microstrip mixer and facilitating improving the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0020] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the third microstrip mixing arm is bent so as to further reduce the space size occupied by the microstrip mixer under the restriction that the third microstrip mixing arm has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to an electrical length of one-half a wavelength.

[0021] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the microstrip mixing line is arranged to be symmetrical with the midline of the line connecting the first mixing port and the second mixing port, so that the electrical length relationship between each of the microstrip mixing arms can be satisfied based on a simple morphological design of the microstrip mixing line, and thus it is easy to implement.

[0022] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the Doppler microwave detection module further includes a local oscillator circuit and an antenna, wherein the local oscillator circuit is configured to allow power to be supplied to output the local oscillator signal, and is fed and connected to the local oscillator signal input port of the microstrip mixer, wherein the antenna is fed and connected to the feedback signal input port of the microstrip mixer, so that the antenna can be fed with the local oscillator signal via the microstrip mixer and input the feedback signal to the microstrip mixer, thereby improving the detection accuracy of the Doppler microwave detection module for the movement of objects in the corresponding detection space based on the above-mentioned structural principle of the microstrip mixer.

[0023] Another object of the present invention is to provide a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the detection accuracy of the Doppler microwave detection module is improved and is suitable for combined detection of motion characteristics including human movement, micro-motion, breathing and heartbeat.

[0024] According to one aspect of the present invention, the present invention provides a microstrip mixer, wherein the microstrip mixer is adapted to receive a local oscillator signal and a feedback signal, and output a Doppler intermediate frequency signal corresponding to the frequency / phase difference between the local oscillator signal and the feedback signal in a mixing detection manner, wherein the microstrip mixer comprises:

[0025] A bridge, wherein the bridge comprises a current suppression element and a microstrip mixing line, wherein the current suppression element is set as a resistor element or a high-frequency inductor element in the form of a component, and is connected between the two ends of the microstrip mixing line, wherein the microstrip mixing line has a first mixing port, a local oscillator signal input port suitable for inputting the local oscillator signal, a feedback signal input port suitable for outputting the local oscillator signal and inputting the feedback signal, and a second mixing port, and the microstrip mixing line has a first microstrip mixing arm defined between the end and the first mixing port. , a second microstrip mixing arm defined between the first mixing port and the local oscillator signal input port, a third microstrip mixing arm defined between the local oscillator signal input port and the feedback signal input port, a fourth microstrip mixing arm defined between the feedback signal input port and the second mixing port, and a fifth microstrip mixing arm defined between the second mixing port and the other end, wherein the second microstrip mixing arm and the fourth microstrip mixing arm have equal electrical lengths, and the third microstrip mixing arm has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to one-half of a wavelength;

[0026] Two mixing tubes, wherein two ends of the two mixing tubes with different polarities belonging to different mixing tubes are connected to the first mixing port and the second mixing port respectively, and the other two ends of the two mixing tubes with different polarities belonging to different mixing tubes are grounded, and;

[0027] An intermediate frequency output port, wherein the intermediate frequency output port is located at the microstrip mixing line, so that the local oscillator signal is input to the local oscillator signal input port, and the feedback signal is input to the feedback signal input port, and the Doppler intermediate frequency signal is output at the intermediate frequency output port.

[0028] In one embodiment, the first microstrip mixing arm and the fifth microstrip mixing arm are configured to have equal electrical lengths.

[0029] In one embodiment, the two ends of the two mixing tubes connected to the first mixing port and the second mixing port and the connection between the corresponding first mixing port and the second mixing port have the same electrical length.

[0030] In one embodiment, the intermediate frequency output port is located in the middle of the third microstrip mixing arm.

[0031] In one embodiment, a circuit formed by a line through which the first mixing port is grounded via one of the mixing tubes and a line through which the second mixing port is grounded via another mixing tube between the first mixing port and the second mixing port is defined as a high-frequency filtering circuit, wherein the microstrip mixer further comprises at least one metal patch, wherein the metal patch is connected to the high-frequency filtering circuit so as to form a connection between the grounded distributed capacitance and the high-frequency filtering circuit by forming a distributed capacitance with the ground, thereby improving the high-frequency filtering characteristics of the high-frequency filtering circuit.

[0032] In one embodiment, in the high-frequency filter circuit, the first mixing port is connected to at least one of the metal patches via a line where one of the mixing tubes is grounded and the second mixing port is connected to at least one of the metal patches via a line where another of the mixing tubes is grounded.

[0033] In one embodiment, the microstrip mixer further comprises a ground patch, wherein the ground patch is grounded, and wherein both ends of the two mixing tubes that are grounded are grounded in a state of being connected to the ground patch.

[0034] In one embodiment, the microstrip mixing line is arranged symmetrically about a midline of a line connecting the first mixing port and the second mixing port.

[0035] In one embodiment, the third microstrip mixing arm is bent.

[0036] In one embodiment, in the state where the current suppressing element is set as the resistance element, the resistance element is a zero-ohm resistance element.

[0037] In one embodiment, the connection lines between the two mixing tubes and the first mixing port and the second mixing port are located in an annular area defined by the connection line between the first mixing port and the second mixing port and the second microstrip mixing arm, the third microstrip mixing arm and the fourth microstrip mixing arm.

[0038] In one embodiment, the first mixing port is connected to the corresponding mixing tube via an independent microstrip line extending integrally from the first mixing port to the first microstrip mixing arm and the second microstrip mixing arm, and the second mixing port is connected to the corresponding mixing tube via an independent microstrip line extending integrally from the second mixing port to the fourth microstrip mixing arm and the fifth microstrip mixing arm.

[0039] In one embodiment, of the two ends of the two mixing tubes connected to the first mixing port and the second mixing port, the end connected to the first mixing port is connected to the first mixing port in a state of being connected to the first microstrip mixing arm, and the end connected to the second mixing port is connected to the second mixing port in a state of being connected to the fifth microstrip mixing arm.

[0040] In one embodiment, the two mixing tubes are within an annular region defined by the microstrip mixing line and the bridge formed by the current suppression element connected between two ends of the microstrip mixing line.

[0041] In one embodiment, the two mixing tubes are outside the annular region defined by the microstrip mixing line and the bridge formed by the current suppression element connected between two ends of the microstrip mixing line.

[0042] According to another aspect of the present invention, the present invention also provides a Doppler microwave detection module, the Doppler microwave detection module comprising:

[0043] A local oscillator circuit, wherein the local oscillator circuit is configured to be powered to output a local oscillator signal;

[0044] An antenna, wherein the antenna comprises a reference ground and a radiation source spaced from the reference ground, so as to equivalently constitute an open capacitor and be able to receive a feedback signal in an electromagnetic environment; and

[0045] A microstrip mixer, wherein the microstrip mixer comprises:

[0046] A microstrip mixing line, wherein the microstrip mixing line has, from one end thereof, a first mixing port, a local oscillator signal input port suitable for inputting the local oscillator signal, a feedback signal input port suitable for outputting the local oscillator signal and inputting the feedback signal, and a second mixing port, and the microstrip mixing line has a first microstrip mixing arm defined between the end and the first mixing port, a second microstrip mixing arm defined between the first mixing port and the local oscillator signal input port, a third microstrip mixing arm defined between the local oscillator signal input port and the feedback signal input port, a fourth microstrip mixing arm defined between the feedback signal input port and the second mixing port, and a fourth microstrip mixing arm defined between the feedback signal input port and the second mixing port. a fifth microstrip mixing arm between the second mixing port and the other end, wherein the microstrip mixing lines are connected end to end to form a ring-shaped microstrip line shape in which the first microstrip mixing arm and the fifth microstrip mixing arm are integrally connected, wherein the second microstrip mixing arm and the fourth microstrip mixing arm have equal electrical lengths, and the third microstrip mixing arm has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to one-half of a wavelength, wherein the local oscillator signal input port is fed and connected to the local oscillator circuit and the local oscillator signal is connected in a state where the local oscillator circuit is powered, wherein the radiation source is fed and connected to the feedback signal input port and is fed by the local oscillator signal and inputs the feedback signal to the microstrip mixer;

[0047] Two mixing tubes, wherein two ends of the two mixing tubes with different polarities belonging to different mixing tubes are respectively connected to the first mixing port and the second mixing port, and the other two ends of the two mixing tubes with different polarities belonging to different mixing tubes are grounded, wherein the connection lines between the two mixing tubes and the first mixing port and the second mixing port are located in an annular area defined by the connection line between the first mixing port and the second mixing port and the second microstrip mixing arm, the third microstrip mixing arm and the fourth microstrip mixing arm, and;

[0048] An intermediate frequency output port, wherein the intermediate frequency output port is located at the microstrip mixing line, so that the local oscillator signal is input to the local oscillator signal input port, and the feedback signal is input to the feedback signal input port, and the Doppler intermediate frequency signal is output at the intermediate frequency output port.

[0049] In one embodiment, the feeding connection between the radiation source and the feedback signal input port is in the form of a disconnected connection coupled via a corresponding capacitor in a physical circuit.

[0050] In one embodiment, the feeding connection between the local oscillator circuit and the feedback signal input port is in the form of a disconnected connection coupled via a corresponding capacitor in a physical circuit.

[0051] In one embodiment, the two mixing tubes are within the annular region defined by the microstrip mixing line.

[0052] In one embodiment, the two mixing tubes are outside the annular region defined by the microstrip mixing line.

[0053] In one embodiment, the two ends of the two mixing tubes connected to the first mixing port and the second mixing port and the connection between the corresponding first mixing port and the second mixing port have the same electrical length.

[0054] In one embodiment, the microstrip mixer further comprises a ground patch, wherein the ground patch is grounded in a state of being connected to the reference ground, and wherein the two ends of the two mixing tubes that are grounded are grounded in a state of being connected to the ground patch.

[0055] In one embodiment, the third microstrip mixing arm is bent.

[0056] In one embodiment, the intermediate frequency output port is located in the middle of the third microstrip mixing arm.

[0057] In one embodiment, the microstrip mixing line is arranged symmetrically about a midline of a line connecting the first mixing port and the second mixing port.

[0058] In one embodiment, a circuit formed by a line through which the first mixing port is grounded via one of the mixing tubes and a line through which the second mixing port is grounded via another mixing tube between the first mixing port and the second mixing port is defined as a high-frequency filtering circuit, wherein the microstrip mixer further includes at least one metal patch, wherein the metal patch is connected to the high-frequency filtering circuit so as to form a connection between the grounded distributed capacitance and the high-frequency filtering circuit by forming a distributed capacitance with the reference ground, thereby improving the high-frequency filtering characteristics of the high-frequency filtering circuit.

[0059] In one embodiment, in the high-frequency filter circuit, the first mixing port is connected to at least one of the metal patches via a line where one of the mixing tubes is grounded and the second mixing port is connected to at least one of the metal patches via a line where another of the mixing tubes is grounded.

[0060] Further objects and advantages of the present invention will be fully apparent from an understanding of the following description and the accompanying drawings.

[0061] These and other objects, features and advantages of the present invention will be more fully understood from the following detailed description, accompanying drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1Schematic diagram of the equivalent circuit principle of an existing balanced mixer.

[0063] Figure 2 The microstrip structure diagram of an existing microstrip balanced mixer using a two-branch 3dB bridge based on the equivalent circuit principle of the existing balanced mixer.

[0064] Figure 3 The figure is a schematic diagram of a microstrip structure of an existing two-branch bridge based on the equivalent circuit principle of an existing balanced mixer.

[0065] Figure 4 It is a schematic diagram of the microstrip structure of a three-branch bridge based on the equivalent circuit principle of an existing balanced mixer.

[0066] Figure 5 Schematic diagram of the microstrip structure of a variable resistance bridge based on the equivalent circuit principle of an existing balanced mixer.

[0067] Figure 6 It is a schematic diagram of the microstrip structure of a ring-shaped two-branch variable resistance bridge based on the equivalent circuit principle of an existing balanced mixer.

[0068] Figure 7 Schematic diagram of the microstrip structure of a ring bridge based on the equivalent circuit principle of an existing balanced mixer.

[0069] Figure 8 Schematic diagram of the microstrip structure of a broadband ring bridge based on the equivalent circuit principle of an existing balanced mixer.

[0070] Fig. 9 Schematic diagram of the microstrip structure of a 180° hybrid ring bridge based on the equivalent circuit principle of an existing balanced mixer.

[0071] Fig.10 It is a schematic diagram of the structure of another balanced mixer based on the equivalent circuit principle of the existing balanced mixer.

[0072] Fig.11 It is a frequency selection characteristic diagram of the balanced mixer under the condition of satisfying impedance matching.

[0073] Fig.12 This is an anti-interference test diagram of the balanced mixer under the condition of satisfying impedance matching.

[0074] Fig.13 FIG. 4 is a schematic diagram of an equivalent circuit principle of a microstrip mixer according to an embodiment of the present invention.

[0075] Fig.14A The figure is a schematic diagram of a microstrip structure of the microstrip mixer according to the equivalent circuit principle of the above embodiment of the present invention.

[0076] Fig. 14BIt is a schematic diagram of a microstrip structure deformation of the microstrip mixer according to the equivalent circuit principle of the above embodiment of the present invention.

[0077] Fig.15A Schematic diagram of another microstrip structure of the microstrip mixer based on the equivalent circuit principle of the above embodiment according to the present invention.

[0078] Fig. 15B It is a schematic diagram of a microstrip structure deformation of the microstrip mixer according to the equivalent circuit principle of the above embodiment of the present invention.

[0079] Fig.16A Schematic diagram of another microstrip structure of the microstrip mixer based on the equivalent circuit principle of the above embodiment according to the present invention.

[0080] Fig. 16B It is a schematic diagram of a microstrip structure deformation of the microstrip mixer according to the equivalent circuit principle of the above embodiment of the present invention.

[0081] Fig. 16C It is a schematic diagram of a microstrip structure deformation of the microstrip mixer according to the equivalent circuit principle of the above embodiment of the present invention.

[0082] Fig.17 The figure is a frequency selection characteristic diagram of the microstrip mixer under the condition of satisfying impedance matching according to the equivalent circuit principle of the above embodiment of the present invention.

[0083] Fig.18 This is an anti-interference test diagram of the microstrip mixer under the condition of satisfying impedance matching according to the equivalent circuit principle of the above embodiment of the present invention.

[0084] Fig.19 The figure is a schematic diagram of an equivalent circuit of a Doppler microwave detection module having the microstrip mixer according to the present invention. DETAILED DESCRIPTION

[0085] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0086] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0087] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0088] The present invention provides a microstrip mixer and a Doppler microwave detection module having the microstrip mixer, wherein the Doppler microwave detection module is suitable for being fed by a local oscillator signal through the microstrip mixer to transmit a detection beam corresponding to the frequency of the local oscillator signal in a corresponding detection space, and receiving an echo formed by the detection beam being reflected by at least one object in the detection space to receive a feedback signal, wherein the mixer receives the feedback signal and outputs a Doppler intermediate frequency signal corresponding to the frequency difference between the local oscillator signal and the feedback signal in a mixing and detection manner, and based on the principle of the Doppler effect, the fluctuation in amplitude of the Doppler intermediate frequency signal theoretically corresponds to the movement of an object in the detection space.

[0089] Referring to the accompanying drawings of the present invention Figures 13 to 16CAs shown, the equivalent circuit principle of the microstrip mixer of the present invention and the structure of the microstrip mixer of different embodiments based on the equivalent circuit principle are respectively illustrated, wherein the balanced mixer includes a bridge 10, two mixing tubes 20 and an intermediate frequency output port 30, wherein the bridge 10 includes a current suppression element 11 arranged in the form of components and a microstrip mixing line 12 arranged in the form of a microstrip line and connected between the two ends of the current suppression element 11, wherein the current suppression element 11 is arranged in the form of a resistor element or a high-frequency inductor element and has a transient suppression characteristic for an electrical signal, Different from the resistance or inductance characteristics of the microstrip mixer line 12 in the form of a microstrip line under the action of a high-frequency electrical signal, the impedance characteristics of the bridge 10 can be maintained in a state matching the impedance characteristics of the microstrip mixer line 12 under the action of the high-frequency local oscillator signal. In this way, by connecting the current suppression element 11 between the two ends of the microstrip mixer line 12, the transient electrical signal in the bridge 10 is suppressed while maintaining the impedance characteristics of the bridge 10, thereby ensuring the impedance matching design of the microstrip mixer and improving the frequency selection characteristics of the microstrip mixer.

[0090] Specifically, the intermediate frequency output port 30 is located at the microstrip mixing line 12, wherein the microstrip mixing line 12 has a first mixing port 1201, a local oscillator signal input port 1202 suitable for inputting the local oscillator signal, a feedback signal input port 1203 suitable for outputting the local oscillator signal and inputting the feedback signal, and a second mixing port 1204 in sequence from one end thereof, and the corresponding microstrip mixing line 12 has a first microstrip mixing arm 121 defined between the end and the first mixing port 1201, and a second microstrip mixing arm 122 defined between the first mixing port 1201 and the local oscillator signal input port 1202, A third microstrip mixing arm 123 defined between the local oscillator signal input port 1202 and the feedback signal input port 1203, a fourth microstrip mixing arm 124 defined between the feedback signal input port 1203 and the second mixing port 1204, and a fifth microstrip mixing arm 125 defined between the second mixing port 1204 and the other end, so that the two ends of the current suppression element 11 are connected to the first mixing port 1201 and the fifth microstrip mixing arm 125 respectively in a state where the current suppression element 11 is connected between the two ends of the microstrip mixing line 12. The state of being connected to the second mixing port 1204 corresponds to forming a connection relationship with a bridge effect between the current suppression element 11 and the microstrip mixing line 12, wherein the second microstrip mixing arm 122 and the fourth microstrip mixing arm 124 have equal electrical lengths, and the third microstrip mixing arm 123 has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to one-half of a wavelength, wherein the two ends of the two mixing tubes 20 with different polarities belonging to different mixing tubes 20 are respectively connected to the first mixing port 1201 and the second mixing port 1204, and the two mixing tubes 20 belonging to different The other two ends of the mixer tube with different polarities are grounded to ensure that the two ends are short-circuited to the ground at high frequency, and a high-frequency filter circuit is formed between the first mixer port 1201 and the second mixer port 1204, which is composed of a line grounded through one of the mixer tubes 20 at the first mixer port 1201 and a line grounded through the other mixer tube 20 at the second mixer port 1204. In this way, the power of the local oscillator signal and the feedback signal respectively input from the local oscillator signal input port 1202 and the feedback signal input port 1203 can be fully loaded on the two mixer tubes 20 without leaking to the intermediate frequency output port 30.

[0091] Preferably, in these embodiments of the present invention, the two mixing tubes 20 are arranged in the form of diodes, and the two ends of the two diodes with different polarities belonging to different diodes are respectively connected to the first mixing port 1201 and the second mixing port 1204. The connection structure specifically corresponds to: the positive electrode of one of the diodes is connected to the second mixing port 1204, and the negative electrode of the other diode is connected to the first mixing port 1201, which is beneficial to improve the mixing efficiency of the microstrip mixer.

[0092] It is worth mentioning that when the current suppression element 11 is set to the state of the resistance element, the resistance element preferably adopts a zero-ohm resistance element to suppress the transient electrical signal in the bridge 10 while avoiding the change of the impedance characteristics of the bridge 10, thereby further facilitating the impedance characteristics of the bridge 10 to match the impedance characteristics of the microstrip mixing line 12 under the action of the high-frequency local oscillator signal.

[0093] In particular, the first microstrip mixing arm 121 and the fifth microstrip mixing arm 125 are preferably configured to have equal electrical lengths, and the corresponding first mixing port 1201 and the second mixing port 1204 are connected to the current suppression element 11 with equal electrical lengths, so as to be beneficial to the cancellation of the noise current in the Doppler intermediate frequency signal and to release the position limitation of the intermediate frequency output port 30 on the microstrip mixing line 12. The corresponding wiring methods of the microstrip mixer are diverse and can adapt to different line layout requirements, and at the same time are beneficial to improve the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0094] Furthermore, the two ends of the two mixing tubes 20 with different polarities belonging to different mixing tubes 20 are preferably connected to the first mixing port 1201 and the second mixing port 1204 with equal electrical lengths, so that when the two ends are respectively connected to the first mixing port 1201 and the second mixing port 1204, it is ensured that the connection between the first mixing port 1201 and the second mixing port 1204 and the current suppression element 11 has equal electrical length, which is beneficial to ensure the feedback accuracy of the Doppler intermediate frequency signal on the movement of the object in the corresponding detection space.

[0095] In particular, the intermediate frequency output port 30 is preferably located in the middle position of the third microstrip mixing arm 123, and the two sections of the third microstrip mixing arm 123 bounded by the intermediate frequency output port 30 have equal electrical lengths, thereby avoiding the influence of the non-equal electrical length connection between the first mixing port 1201 and the second mixing port 1204 and the current suppression element 11 on the Doppler intermediate frequency signal caused by errors generated in the production process of the microstrip mixing line 12 and the assembly process of the current suppression element 11 and the mixing tube 20. Correspondingly, while ensuring the feedback accuracy of the Doppler intermediate frequency signal to the movement of the object in the corresponding detection space, the accuracy requirements for the production process of the microstrip mixing line 12 and the assembly process of the current suppression element 11 and the mixing tube 20 are reduced, thereby being simple, easy to implement and low-cost.

[0096] Optionally, the microstrip mixer further includes at least one metal patch 40, wherein the metal patch 40 is connected to the high-frequency filtering circuit so as to be suitable for improving the high-frequency filtering characteristics of the high-frequency filtering circuit by forming a distributed capacitance with the ground, thereby correspondingly improving the frequency selection characteristics of the microstrip mixer and facilitating improving the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0097] Preferably, in the high-frequency filtering circuit formed by the line through which the first mixing port 1201 is grounded via one of the mixing tubes 20, and the line through which the second mixing port 1204 is grounded via another mixing tube 20, the line through which the first mixing port 1201 is grounded via one of the mixing tubes 20 and the line through which the second mixing port 1204 is grounded via another mixing tube 20 are respectively connected to at least one metal patch 40, thereby further facilitating the cancellation of noise current in the Doppler intermediate frequency signal.

[0098] Furthermore, in these embodiments of the present invention, the connection lines between the two mixing tubes 20 and the first mixing port 1201 and the second mixing port 1204 are located in the annular area defined by the connection line between the first mixing port 1201 and the second mixing port 1204 and the second microstrip mixing arm 122, the third microstrip mixing arm 123 and the fourth microstrip mixing arm 124, so as to reduce the space size occupied by the microstrip mixer, and to form and intensify the angle mutation of the connection lines between the two mixing tubes 20 and the first mixing port 1201 and the second mixing port 1204 relative to the second microstrip mixing arm 122 and the fourth microstrip mixing arm 124 in the extension direction, thereby facilitating the maintenance of the impedance characteristics of the microstrip mixing line 12, and further suppressing the transient electrical signal in the bridge 10 in parallel with the current suppression element 11, thereby correspondingly ensuring the feedback accuracy of the Doppler intermediate frequency signal to the movement of the object in the corresponding detection space.

[0099] That is to say, in some embodiments of the present invention, in the state where the connection line between the two mixing tubes 20 and the first mixing port 1201 and the second mixing port 1204 is located within the annular area defined by the connection line between the first mixing port 1201 and the second mixing port 1204 and the second microstrip mixing arm 122, the third microstrip mixing arm 123 and the fourth microstrip mixing arm 124, the current suppression element 11 may not be provided, and the corresponding bridge 10 is in the form of an annular microstrip line formed by connecting the microstrip mixing lines 12 end to end, and the corresponding first microstrip mixing arm 121 and the fifth microstrip mixing arm 125 are integrally connected, and the present invention does not impose any restrictions on this.

[0100] Specifically, in these embodiments of the present invention, the microstrip mixer further includes a ground patch 50, wherein the ground patch 50 is grounded, wherein the two ends of the two mixing tubes 20 with different polarities belonging to different mixing tubes 20 are respectively connected to the first mixing port 1201 and the second mixing port 1204, and the other two ends of the two mixing tubes 20 with different polarities belonging to different mixing tubes 20 are connected to the ground patch 50 and grounded.

[0101] It is worth mentioning that the connection between the first mixing port 1201 and the corresponding mixing tube 20 allows corresponding Fig.14A and Fig. 14B as well as Fig. 16C The independent microstrip line extending from the first mixing port 1201 to the first microstrip mixing arm 121 and the second microstrip mixing arm 122 is directly connected to the corresponding mixing tube 20, or corresponds to FIG. 15A to FIG. 16BThe first microstrip mixing arm 121 is connected to the corresponding mixing tube 20; similarly, the connection between the second mixing port 1204 and the corresponding mixing tube 20 allows corresponding Fig.14A and Fig. 14B as well as Fig. 16C The independent microstrip line extending from the second mixing port 1204 to the fourth microstrip mixing arm 124 and the fifth microstrip mixing arm 125 is directly connected to the corresponding mixing tube 20, or corresponds to FIG. 15A to FIG. 16B The fifth microstrip mixer arm 125 is connected to the corresponding mixer tube 20 , which is not limited in the present invention.

[0102] That is, corresponding to FIG. 15A to FIG. 16B The two ends of the two mixing tubes 20 with different polarities belonging to different mixing tubes 20 are respectively connected to the first mixing port 1201 in a manner of being connected to the first microstrip mixing arm 121 and connected to the second mixing port 1204 in a manner of being connected to the fifth microstrip mixing arm 125, so as to simplify the structural design of the microstrip mixer, and the first microstrip mixing arm 121 and the fifth microstrip mixing arm 125 are respectively connected to the first mixing port 1201 and the second mixing port 1204 and the second microstrip mixing arm 122, the first microstrip mixing arm 121 and the fifth microstrip mixing arm 125 are respectively connected to the first mixing port 1201 and the second mixing port 1204 and the second microstrip mixing arm 122. The third microstrip mixing arm 123 and the fourth microstrip mixing arm 124 extend integrally within the annular area defined by the second microstrip mixing arm 122 and the fourth microstrip mixing arm 124, forming a state in which the connection lines between the two mixing tubes 20 and the first mixing port 1201 and the second mixing port 1204 are located within the annular area defined by the second microstrip mixing arm 122, the third microstrip mixing arm 123 and the fourth microstrip mixing arm 124, and the present invention is not limited to this.

[0103] It is worth mentioning that the two ends of the current suppressing element 11 are respectively connected to the first mixing port 1201 and the second mixing port 1204 via the first microstrip mixing arm 121 and the fifth microstrip mixing arm 125, and the two ends with different polarities of the two mixing tubes 20 belonging to different mixing tubes 20 are respectively connected to the first mixing port 1201 and the second mixing port 1204, and the other two ends with different polarities of the two mixing tubes 20 belonging to different mixing tubes 20 are grounded and connected, and the current suppressing element 11 and the two mixing tubes 20 are in a parallel state between the first mixing port 1201 and the second mixing port 1204, wherein the parallel connection order of the current suppressing element 11 and the two mixing tubes 20 between the first mixing port 1201 and the second mixing port 1204 does not constitute a limitation to the present invention.

[0104] That is, in some embodiments of the present invention, corresponding to FIG. 14A to FIG. 16C , the two mixing tubes 20 are within the annular region defined by the bridge 10 formed by the microstrip mixing line 12 and the current suppression element 11 connected between the two ends of the microstrip mixing line 12, and in some other embodiments of the present invention, the two mixing tubes 20 are outside the annular region defined by the bridge 10 formed by the microstrip mixing line 12 and the current suppression element 11 connected between the two ends of the microstrip mixing line 12, and can also be increased by adding the first microstrip mixing arm 121 and the fifth microstrip mixing arm 125 relative to the angle mutation amount of the second microstrip mixing arm 122 and the fourth microstrip mixing arm 124 in the extension direction, allowing the connection lines between the two mixing tubes 20 and the first mixing port 1201 and the second mixing port 1204 to be located within the annular area defined by the connection line between the first mixing port 1201 and the second mixing port 1204 and the second microstrip mixing arm 122, the third microstrip mixing arm 123 and the fourth microstrip mixing arm 124, and the present invention is not limited to this.

[0105] Furthermore, in these embodiments of the present invention, the third microstrip mixing arm 123 is bent, so that the space occupied by the microstrip mixer can be further reduced under the restriction that the third microstrip mixing arm 123 has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to one-half of a wavelength.

[0106] In particular, corresponding to FIG. 16A to FIG. 16C, in the state where the third microstrip mixing arm 123 is bent, the microstrip mixing line 12 is designed in a non-bent state at the position of the local oscillator signal input port 1202 defined between the second microstrip mixing arm 122 and the third microstrip mixing arm 123, and the position of the feedback signal input port 1203 defined between the third microstrip mixing arm 123 and the fourth microstrip mixing arm 124, that is, the local oscillator signal input port 1202 and the feedback signal input port 1203 are distinguished from each other. FIG. 14A to FIG. 15B It is not located at the inflection point of the microstrip mixing line 12, so that under the restriction that the third microstrip mixing arm 123 has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to an electrical length of half a wavelength, by bending the third microstrip mixing arm 123, while reducing the space size occupied by the microstrip mixer, the area of ​​the annular region defined by the connection line of the first mixing port 1201 and the second mixing port 1204 and the second microstrip mixing arm 122, the third microstrip mixing arm 123 and the fourth microstrip mixing arm 124 is guaranteed, which is beneficial to the line layout of the two mixing tubes 20 in the annular region.

[0107] Further, corresponding to FIG. 14A to FIG. 16C In the illustrated embodiments, the microstrip mixing line 12 is arranged to be symmetrical with respect to the midline of the line connecting the first mixing port 1201 and the second mixing port 1204, so that the electrical length relationship between the microstrip mixing arms can be satisfied based on a simple morphological design of the microstrip mixing line, and thus it is easy to implement.

[0108] It is worth mentioning that, based on the equivalent circuit principle of the microstrip mixer of the present invention, the structural form of the microstrip mixer is diverse, wherein the second microstrip mixing arm 122 and the fourth microstrip mixing arm 124 have equal electrical lengths, and the third microstrip mixing arm 123 has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to one-half of a wavelength, and the two ends of the two mixing tubes 20 with different polarities belonging to different mixing tubes 20 are respectively connected to the first mixing port 1201 and the second mixing port 1204, and the other two ends of the two mixing tubes 20 with different polarities belonging to different mixing tubes are grounded, based on the current suppression element 11 provided in the form of components being connected to the two ends of the microstrip mixing line 12 and / or the two mixing tubes 20 and the first mixing port 1201. The structural design of the connection line between the first mixing port 1201 and the second mixing port 1204 is located in the annular area defined by the connection line between the first mixing port 1201 and the second mixing port 1204 and the second microstrip mixing arm 122, the third microstrip mixing arm 123 and the fourth microstrip mixing arm 124. It can suppress the transient change of the electrical signal in the bridge 10 while maintaining the impedance characteristics of the bridge 10, and correspondingly, while ensuring the impedance matching design of the microstrip mixer, the frequency selection characteristics of the microstrip mixer are improved. Accordingly, the microstrip mixer has lower loss and narrowed bandwidth only in the working frequency band corresponding to the local oscillator signal frequency, and can ensure the output signal strength and anti-interference performance of the Doppler intermediate frequency signal, which is beneficial to improve the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0109] Specific reference to the accompanying drawings of the present invention Fig.17 and Fig.18 As shown, based on Fig.16A The structural form of the balanced mixer shown in the figure is an example of impedance matching design of the balanced mixer at an operating frequency band of 5.8 GHz ISM band, and the frequency selection characteristic diagram and anti-interference test diagram of the balanced mixer under the condition of satisfying impedance matching are respectively illustrated.

[0110] Corresponds to Fig.17 Based on the characterization of the reflection coefficients of the local oscillator signal input port 1202 and the feedback signal input port 1203 by the S11 curve and the S22 curve, the balanced mixer presents an obvious narrow trough in the working frequency band of 5.8 GHz, and the corresponding microstrip mixer has lower loss and narrowed bandwidth in the working frequency band, and the corresponding microstrip mixer has excellent frequency selection characteristics in the working frequency band and can ensure the output signal strength of the corresponding Doppler intermediate frequency signal.

[0111] Furthermore, the S11 curve and the S22 curve of the microstrip mixer tend to be flat in the non-working frequency band and have a higher loss, that is, the S11 curve and the S22 curve of the microstrip mixer only show obvious narrow troughs in the working frequency band, corresponding to the microstrip mixer having lower losses and narrowed bandwidth only in the working frequency band, and the corresponding microstrip mixer has excellent frequency selection characteristics and can ensure the output signal strength and anti-interference performance of the Doppler intermediate frequency signal, which is beneficial to improve the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0112] Corresponds to Fig.18 , based on the interference test of the interference signal in the frequency range of 80MHz to 6GHz (corresponding to the frequency range specified in the radiation immunity test of the latest standard IEC 61000-4-3 / GBT 17626.3) emitted dynamically to the Doppler intermediate frequency signal output by the balanced mixer, the Doppler intermediate frequency signal under the interference signal of a certain frequency is screenshotted, wherein the interference of the interference signal of this frequency range to the balanced mixer does not produce obvious amplitude change in the Doppler intermediate frequency signal, and the corresponding Doppler intermediate frequency signal tends to be flat, then the corresponding Doppler microwave detection module can pass the radiation immunity test of the IEC 61000-4-3 / GB T 17626.3 standard, which is conducive to the promotion of the Doppler microwave detection module and the improvement of commercial competitiveness in the field of Doppler microwave detection.

[0113] Further reference is made to the accompanying drawings of the present invention. Fig.19 , the equivalent circuit principle of the Doppler microwave detection module with the microstrip mixer is illustrated, wherein the Doppler microwave detection module further includes a local oscillator circuit 60 and an antenna 70, wherein the local oscillator circuit 60 is configured to allow power to be supplied and output the local oscillator signal, and is fed and connected to the local oscillator signal input port 1202 of the microstrip mixer, wherein the antenna 70 is fed and connected to the feedback signal input port 1203 of the microstrip mixer, so that the antenna 70 can be fed with the local oscillator signal through the microstrip mixer and input the feedback signal to the microstrip mixer, correspondingly based on the above-mentioned structural principle of the microstrip mixer, the detection accuracy of the Doppler microwave detection module for the movement of objects in the corresponding detection space is improved.

[0114] It is worth mentioning that the feeding connection between the local oscillator circuit 60 and the feedback signal input port 1203 of the microstrip mixer, and the feeding connection between the antenna 70 and the feedback signal input port 1203 of the microstrip mixer are path connections under the action of high-frequency electrical signals. Therefore, the feeding connection between the local oscillator circuit 60 and the feedback signal input port 1203 of the microstrip mixer, and the feeding connection between the antenna 70 and the feedback signal input port 1203 of the microstrip mixer are allowed to be in the form of a direct path connection in the physical circuit, or in the form of a disconnected connection coupled through corresponding capacitors (such as microstrip coupling capacitors, distributed capacitors and capacitor elements), and the present invention does not impose any restrictions on this.

[0115] Preferably, the feeding connection between the antenna 70 and the feedback signal input port 1203 of the microstrip mixer is in the form of an open-circuit connection coupled by a corresponding capacitor in the physical circuit, so as to further improve the anti-interference performance of the Doppler microwave detection module while ensuring the stability of the Doppler microwave detection module through the high impedance characteristics of the capacitor to the low-frequency signal and the isolation characteristics to the DC signal.

[0116] Optionally, the feeding connection between the local oscillator circuit 60 and the feedback signal input port 1203 of the microstrip mixer is in the form of an open-circuit connection coupled by a corresponding capacitor in the physical circuit, so as to further improve the anti-interference performance of the Doppler microwave detection module while ensuring the stability of the Doppler microwave detection module through the high impedance characteristics of the capacitor to the low-frequency signal and the isolation characteristics to the DC signal.

[0117] Furthermore, the antenna 70 includes a reference ground and a radiation source spaced from the reference ground, so as to form an open capacitor C0 equivalently to generate the feedback signal in an electromagnetic environment, wherein the radiation source is fed and connected to the feedback signal input port 1203 of the microstrip mixer to form a feeding connection relationship between the antenna 70 and the feedback signal input port 1203, wherein the reference ground is grounded and equivalent to Fig.19 The equivalent capacitance C0 is grounded, corresponding to the radiation source being equivalent to Fig.19 The other pole of the open capacitor C0, wherein the ground patch 50 is grounded in a state of being connected to the reference ground, and when the high-frequency filtering circuit is connected to the metal patch 40, the metal patch 40 can form a distributed capacitance with the reference ground to improve the high-frequency filtering characteristics of the high-frequency filtering circuit.

[0118] It is worth mentioning that in the description of the present invention, due to the existence of industrial errors, the description and limitation based on the relationship of electrical length are allowed to have an error range of 20% in actual measurement, such as "the second microstrip mixing arm 122 and the fourth microstrip mixing arm 124 have equal electrical lengths, and the third microstrip mixing arm 123 has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to one-half of a wavelength" should be understood as: the second microstrip mixing arm 122 and the fourth microstrip mixing arm 124 have equal electrical lengths within an error range of 20%, and the third microstrip mixing arm 123 has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to one-half of a wavelength within an error range of 20%.

[0119] Those skilled in the art will appreciate that the above embodiments are merely examples, wherein features of different embodiments may be combined with each other to obtain implementation methods that are easily conceivable based on the contents disclosed in the present invention but are not explicitly indicated in the drawings, and the present invention is not limited thereto.

[0120] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A microstrip mixer, wherein the microstrip mixer is adapted to receive a local oscillator signal and a feedback signal, and output a Doppler intermediate frequency signal corresponding to the frequency / phase difference between the local oscillator signal and the feedback signal in a mixer-detection manner, characterized in that: include: A bridge, wherein the bridge comprises a current suppression element and a microstrip mixer line, wherein the current suppression element is set as a resistor element or a high-frequency inductor element in the form of a component, and is connected between the two ends of the microstrip mixer line, wherein the microstrip mixer line has a first mixer port, a local oscillator signal input port suitable for inputting the local oscillator signal, a feedback signal input port suitable for inputting the feedback signal, and a second mixer port in sequence from one end thereof, and the microstrip mixer line has a first microstrip mixer arm defined between the end and the first mixer port, and a second mixer arm defined between the first mixer port and the feedback signal. a second microstrip mixing arm between the first mixing port and the local oscillator signal input port, a third microstrip mixing arm defined between the local oscillator signal input port and the feedback signal input port, a fourth microstrip mixing arm defined between the feedback signal input port and the second mixing port, and a fifth microstrip mixing arm defined between the second mixing port and the other end, wherein the second microstrip mixing arm and the fourth microstrip mixing arm have equal electrical lengths, and the third microstrip mixing arm has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to one-half of a wavelength; Two mixing tubes, wherein two ends of the two mixing tubes with different polarities belonging to different mixing tubes are respectively connected to the first mixing output port and the second mixing output port, and the other two ends of the two mixing tubes with different polarities belonging to different mixing tubes are grounded, and; An intermediate frequency output port, wherein the intermediate frequency output port is located at the microstrip mixing line, so that the local oscillator signal is input to the local oscillator signal input port, and the feedback signal is input to the feedback signal input port, and the Doppler intermediate frequency signal is output at the intermediate frequency output port. 2 . The microstrip mixer according to claim 1 , wherein the first microstrip mixing arm and the fifth microstrip mixing arm are configured to have equal electrical lengths.

3. The microstrip mixer according to claim 2, wherein the connections between the two ends of the two mixing tubes connected to the first mixing port and the second mixing port and the corresponding first mixing port and the second mixing port have equal electrical lengths. 4 . The microstrip mixer according to claim 3 , wherein the intermediate frequency output port is located in the middle of the third microstrip mixing arm.

5. The microstrip mixer according to claim 4, wherein a circuit formed by a line through which the first mixing port is grounded via one of the mixing tubes and a line through which the second mixing port is grounded via another mixing tube between the first mixing port and the second mixing port is defined as a high-frequency filtering circuit, wherein the microstrip mixer further comprises at least one metal patch, wherein the metal patch is connected to the high-frequency filtering circuit so as to form a connection between the grounded distributed capacitance and the high-frequency filtering circuit by forming a distributed capacitance with the ground, thereby improving the high-frequency filtering characteristics of the high-frequency filtering circuit.

6. The microstrip mixer according to claim 5, wherein in the high-frequency filtering circuit, the first mixing port is connected to at least one of the metal patches via a line through which one of the mixing tubes is grounded and the second mixing port is connected to at least one of the metal patches via a line through which the other mixing tube is grounded.

7. The microstrip mixer according to claim 4, wherein the microstrip mixer further comprises a ground patch, wherein the ground patch is grounded, and wherein both ends of the two mixing tubes that are grounded are grounded in a state of being connected to the ground patch. 8 . The microstrip mixer according to claim 7 , wherein the microstrip mixing line is arranged symmetrically with respect to a center line connecting the first mixing port and the second mixing port. 9 . The microstrip mixer according to claim 8 , wherein the third microstrip mixing arm is bent.

10. The microstrip mixer according to claim 4, wherein in a state where the current suppressing element is set as the resistance element, the resistance element is a zero-ohm resistance element.

11. The microstrip mixer according to any one of claims 1 to 10, wherein the connection lines between the two mixing tubes and the first mixing port and the second mixing port are located in an annular area defined by the connection line between the first mixing port and the second mixing port and the second microstrip mixing arm, the third microstrip mixing arm and the fourth microstrip mixing arm.

12. The microstrip mixer according to claim 11, wherein the two mixing tubes are arranged in the form of diodes, wherein two ends with different polarities belonging to different diodes in the two diodes are respectively connected to the first mixing port and the second mixing port, wherein the anode of one diode is connected to the second mixing port, and the cathode of the other diode is connected to the first mixing port.

13. The microstrip mixer according to claim 11, wherein the first mixing port is connected to the corresponding mixing tube by an independent microstrip line extending from the first mixing port to the first microstrip mixing arm and the second microstrip mixing arm, and the second mixing port is connected to the corresponding mixing tube by an independent microstrip line extending from the second mixing port to the fourth microstrip mixing arm and the fifth microstrip mixing arm.

14. The microstrip mixer according to claim 11, wherein of the two ends of the two mixing tubes connected to the first mixing port and the second mixing port, the end connected to the first mixing port is connected to the first mixing port in a state of being connected to the first microstrip mixing arm, and the end connected to the second mixing port is connected to the second mixing port in a state of being connected to the fifth microstrip mixing arm.

15. The microstrip mixer according to claim 11, wherein the two mixing tubes are within an annular region defined by the microstrip mixing line and the bridge formed by the current suppression element connected between both ends of the microstrip mixing line. 16 . The microstrip mixer according to claim 11 , wherein the two mixing tubes are outside a ring region defined by the microstrip mixing line and the bridge formed by the current suppression element connected between both ends of the microstrip mixing line.

17. A Doppler microwave detection module, characterized in that: include: A local oscillator circuit, wherein the local oscillator circuit is configured to be powered to output a local oscillator signal; An antenna, wherein the antenna comprises a reference ground and a radiation source spaced from the reference ground, so as to constitute an open capacitor equivalently and generate a feedback signal in an electromagnetic environment; as well as A microstrip mixer, wherein the microstrip mixer comprises: A microstrip mixing line, wherein the microstrip mixing line has, from one end thereof, a first mixing port, a local oscillator signal input port for inputting the local oscillator signal, a feedback signal input port for inputting the feedback signal, and a second mixing port, and the microstrip mixing line has a first microstrip mixing arm defined between the end and the first mixing port, a second microstrip mixing arm defined between the first mixing port and the local oscillator signal input port, a third microstrip mixing arm defined between the local oscillator signal input port and the feedback signal input port, a fourth microstrip mixing arm defined between the feedback signal input port and the second mixing port, and a fourth microstrip mixing arm defined between the second mixing port and the feedback signal input port. a fifth microstrip mixing arm between the first and the second microstrip mixing arms and the other end, wherein the microstrip mixing lines are connected end to end to form a ring-shaped microstrip line shape in which the first microstrip mixing arm and the fifth microstrip mixing arm are integrally connected, wherein the second microstrip mixing arm and the fourth microstrip mixing arm have equal electrical lengths, and the third microstrip mixing arm has an electrical length greater than or equal to one-eighth of a wavelength and less than or equal to one-half of a wavelength, wherein the local oscillator signal input port is fed and connected to the local oscillator circuit and the local oscillator signal is connected in a state where the local oscillator circuit is powered, wherein the radiation source is fed and connected to the feedback signal input port and is fed by the local oscillator signal and inputs the feedback signal to the microstrip mixer; Two mixing tubes, wherein two ends of the two mixing tubes with different polarities belonging to different mixing tubes are respectively connected to the first mixing port and the second mixing port, and the other two ends of the two mixing tubes with different polarities belonging to different mixing tubes are grounded, wherein the connection lines between the two mixing tubes and the first mixing port and the second mixing port are located in an annular area defined by the connection line between the first mixing port and the second mixing port and the second microstrip mixing arm, the third microstrip mixing arm and the fourth microstrip mixing arm, and; an intermediate frequency output port, wherein the intermediate frequency output port is located on the microstrip mixing line, so that when the local oscillator signal is input to the local oscillator signal input port and the feedback signal is input to the feedback signal input port, a Doppler intermediate frequency signal corresponding to the frequency / phase difference between the local oscillator signal and the feedback signal is output at the intermediate frequency output port. 18 . The Doppler microwave detection module according to claim 17 , wherein the feed connection between the radiation source and the feedback signal input port is in the form of a disconnected connection coupled via a corresponding capacitor in a physical circuit. 19 . The Doppler microwave detection module according to claim 18 , wherein the feeding connection between the local oscillator circuit and the feedback signal input port is in the form of a disconnected connection coupled via a corresponding capacitor in a physical circuit.

20. The Doppler microwave detection module according to claim 18, wherein the two mixing tubes are within an annular region defined by the microstrip mixing line.

21. The Doppler microwave detection module according to claim 18, wherein the two mixing tubes are outside the annular area defined by the microstrip mixing line.

22. The Doppler microwave detection module according to any one of claims 17 to 21, wherein the connections between the two ends of the two mixing tubes connected to the first mixing port and the second mixing port and the corresponding first mixing port and the second mixing port have equal electrical lengths.

23. The Doppler microwave detection module according to claim 22, wherein the microstrip mixer further comprises a ground patch, wherein the ground patch is grounded in a state of being connected to the reference ground, and wherein the two grounded ends of the two mixing tubes are grounded in a state of being connected to the ground patch.

24. The Doppler microwave detection module according to claim 23, wherein the third microstrip mixing arm is bent. 25 . The Doppler microwave detection module according to claim 24 , wherein the intermediate frequency output port is located in the middle of the third microstrip mixing arm. 26 . The Doppler microwave detection module according to claim 25 , wherein the microstrip mixing line is arranged symmetrically about a center line of a line connecting the first mixing port and the second mixing port.

27. The Doppler microwave detection module according to claim 22, wherein a circuit formed by a line through which the first mixing port is grounded via one of the mixing tubes and a line through which the second mixing port is grounded via another mixing tube between the first mixing port and the second mixing port is defined as a high-frequency filtering circuit, wherein the microstrip mixer further comprises at least one metal patch, wherein the metal patch is connected to the high-frequency filtering circuit so as to form a connection between the grounded distributed capacitance and the high-frequency filtering circuit by forming a distributed capacitance with the reference ground, thereby improving the high-frequency filtering characteristics of the high-frequency filtering circuit.

28. The Doppler microwave detection module according to claim 27, wherein in the high-frequency filtering circuit, the first mixing port is connected to at least one of the metal patches via a line through which one of the mixing tubes is grounded and the second mixing port is connected to at least one of the metal patches via a line through which the other mixing tube is grounded.

29. The Doppler microwave detection module according to claim 22, wherein the two mixing tubes are arranged in the form of diodes, wherein the two ends with different polarities belonging to different diodes in the two diodes are respectively connected to the first mixing port and the second mixing port, wherein the anode of one diode is connected to the second mixing port, and the cathode of the other diode is connected to the first mixing port.

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