Anti-interference Miniaturized Microstrip Mixer and Doppler Microwave Detection Module

Abstract

The present invention provides an anti-interference miniaturized microstrip mixer and a Doppler microwave detection module. The anti-interference miniaturized microstrip mixer includes a bridge. Based on the operating frequency in the 5.8 GHz ISM band, with λ being the electrical length parameter of one wavelength corresponding to the operating frequency, by shortening the electrical length of the bridge to a state less than 0.9λ, while reducing the area of the region defined by the bridge and thus reducing the magnetic flux of the bridge in a magnetic field environment, based on the corresponding structural design of the bridge, while maintaining the mixing characteristics of the bridge, the bridge can be detached from the resonant state at the operating frequency and reduce the radiation and reception capabilities of the bridge for signals corresponding to the operating frequency, correspondingly ensuring the output power and anti-interference performance of the anti-interference miniaturized microstrip mixer, and at the same time improving the anti-interference performance of the Doppler microwave detection module.

Description

Technical Field

[0001] The invention relates to the field of Doppler microwave detection, in particular to an anti-interference miniaturized microstrip mixer and a Doppler microwave detection module. 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. 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 generate 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 detection manner, then 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 to the movement of the object in the detection space, based on the advantages of low noise and high sensitivity of the existing balanced mixer, the mixer of the Doppler microwave detection module of the prior art mainly adopts a balanced mixer.

[0003] Referring to the accompanying drawings of the present invention Figure 1A and Figure 1BAs shown, the equivalent circuit principle and corresponding structure of the existing balanced mixer using a 3dB bridge structure are respectively illustrated. Specifically, the balanced mixer using a 3dB bridge structure 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, and a first microstrip arm 11P connected between the local oscillator signal input port 101P and the feedback signal input port 102P, a second microstrip arm 12P connected between the feedback signal input port 102P and the first mixing port 103P, and a first mixing port 103P and a second mixing port 104P. A third microstrip arm 13P between the frequency mixing port 104P and the local oscillator signal input port 104P is connected to a fourth microstrip arm 14P between the second mixing port 104P and the local oscillator signal input port 101P, correspondingly forming a microstrip frame structure in which the first microstrip arm 11P, the second microstrip arm 12P, the third microstrip arm 13P and the fourth microstrip arm 14P are connected end to end, wherein the first microstrip arm 11P, the second microstrip arm 12P, the third microstrip arm 13P and the fourth microstrip arm 14P are all set to have an electrical length of λ / 4, that is, the annular bridge 10P has an electrical length of λ, and the second microstrip arm 12P and the fourth microstrip arm 14P are parallel to each other, wherein λ is an electrical length parameter of one wavelength corresponding to the frequency of the local oscillator signal, so that there is a 90-degree phase difference between the first mixing port 103P and the second mixing port 104P, wherein the two ends with different polarities belonging to different mixing tubes 20P of the two 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 belonging to different mixing tubes 20P of the two 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 grounded ends of the two mixing tubes 20P. The two ends of the two mixing tubes 20P are electrically connected to the intermediate frequency output port 30P, 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 based on the corresponding impedance matching design, the main difference being the structural variation of the ring bridge 10P. Although the specific implementation of the ring bridge 10P is flexible and varied, the corresponding equivalent circuit structure does not deviate from Figure 1A According to the equivalent circuit principle shown in the figure, when the first microstrip arm 11P, the second microstrip arm 12P, the third microstrip arm 13P and the fourth microstrip arm 14P all have an electrical length of λ / 4, and the second microstrip arm 12P and the fourth microstrip arm 14P are parallel to each other, the structural size of the balanced mixer is limited and difficult to reduce, which is not conducive to circuit layout on the one hand, and has poor anti-interference characteristics on the other hand, making it 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, the balanced mixer is one of the important factors affecting the anti-interference ability of the corresponding Doppler microwave detection module. Since the annular bridge has an electrical length of λ, and λ is a wavelength parameter corresponding to the frequency of the local oscillator signal, when the local oscillator signal and the feedback signal flow through the annular bridge 10P, the annular bridge 10P will produce obvious resonance. At this time, the annular bridge 10P is equivalent to an antenna, which can radiate signals and receive signals through coupling, thereby reducing the radiation anti-interference of the corresponding Doppler microwave detection module. In addition, since the structural size of the balanced mixer is limited and difficult to reduce, the area surrounded by the corresponding annular bridge 10P is large. When there is a magnetic field in the environment where the annular bridge 10P is located, the magnetic flux of the annular bridge 10P is large and can induce a large energy interference signal, thereby reducing the radiation anti-interference of the corresponding Doppler microwave detection module. Therefore, the current balanced mixer has poor anti-interference characteristics and 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. Taking the operating frequency of the 5.8GHz ISM band as an example, the frequency band range of the latest version of the RS radiation immunity test has been increased to 6GHz. The current Doppler microwave detection modules using balanced mixers are generally difficult to pass the European Radio Product Certification (RED). Summary of the invention

[0005] An object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and a Doppler microwave detection module, wherein the interference-resistant miniaturized microstrip mixer includes a bridge, wherein based on an operating frequency of the ISM frequency band of 5.8 GHz, with λ being an electrical length parameter of one wavelength corresponding to the operating frequency, by shortening the electrical length of the bridge to a state less than 0.9λ, while reducing the area of ​​the region defined by the bridge, the bridge is able to leave the resonant state at the operating frequency and reduce the bridge's radiation and receiving capabilities for signals corresponding to the operating frequency, thereby correspondingly ensuring the output power and anti-interference performance of the corresponding Doppler intermediate frequency signal, and thereby facilitating improving the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0006] An object of the present invention is to provide an anti-interference miniaturized microstrip mixer and Doppler microwave detection module, wherein the electrical length of the bridge is less than 0.9λ, and the corresponding signal frequency that can generate resonance in the bridge is greater than 5.8GHz / 0.9=6.4GHz and is outside 1GHz-6GHz. Then, the radiation immunity test based on the IEC 61000-4-3 / GB T 17626.3 standard is difficult to produce an amplitude change in the Doppler intermediate frequency signal that exceeds the standard limit. Accordingly, the pass rate of the Doppler microwave detection module in the radiation immunity test of the IEC 61000-4-3 / GB T 17626.3 standard is improved, 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.

[0007] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and Doppler microwave detection module, wherein the electrical length of the bridge is less than 0.9λ, which is beneficial to reducing the area defined by the bridge relative to the existing balanced mixer, thereby facilitating the adaptability of the bridge to the circuit layout of the corresponding Doppler microwave detection module with a miniaturized design, and correspondingly facilitating the miniaturized design of the Doppler microwave detection module and improving the commercial competitiveness of the Doppler microwave detection module in accordance with the miniaturization trend.

[0008] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and Doppler microwave detection module, wherein the electrical length of the bridge is less than 0.9λ, which is beneficial to reducing the area defined by the bridge relative to the existing balanced mixer, thereby reducing the magnetic flux of the bridge in the magnetic field environment, and correspondingly reducing the energy of the interference signal generated by the bridge in the magnetic field environment based on electromagnetic induction, thereby further improving the anti-interference performance of the corresponding Doppler microwave detection module and improving the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0009] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and Doppler microwave detection module, 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 motion characteristics including human body movement, micro-movement, breathing and heartbeat.

[0010] One object of the present invention is to provide an anti-interference miniaturized microstrip mixer and Doppler microwave detection module, wherein the bridge has a local oscillator signal input port suitable for local oscillator signal input, a feedback signal input port suitable for feedback signal input, a first mixing port, a second mixing port, and a first microstrip arm connected between the local oscillator signal input port and the feedback signal input port, a second microstrip arm connected between the feedback signal input port and the first mixing port, a third microstrip arm connected between the first mixing port and the second mixing port, and a third microstrip arm connected between the second mixing port and the local oscillator signal input port. A fourth microstrip arm is provided between the first and second microstrip arms, wherein the electrical length of the bridge is shortened to less than 0.9λ by shortening the electrical lengths of the second microstrip arm and the fourth microstrip arm to less than λ / 5, respectively, compared with the existing balanced mixer, and when the electrical length of the bridge is less than 0.9λ, within the electrical length range of greater than or equal to λ / 8 and less than or equal to λ / 2, based on the corresponding length and shape setting of the first microstrip arm, a phase difference of 60 degrees to 120 degrees can still be formed between the first mixing port and the second mixing port, thereby maintaining the mixing characteristics of the bridge when the electrical length of the bridge is shortened to less than 0.9λ.

[0011] An object of the present invention is to provide an anti-interference miniaturized microstrip mixer and a Doppler microwave detection module, wherein the anti-interference miniaturized microstrip mixer further comprises two mixing tubes and an intermediate frequency output line led out from the third microstrip arm, 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 line.

[0012] One object of the present invention is to provide an anti-interference miniaturized microstrip mixer and Doppler microwave detection module, wherein the two ends of the two mixing tubes with different polarities belonging to different mixing tubes are respectively connected to the corresponding first mixing port and the second mixing port by 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 limitation of the lead-out position of the intermediate frequency output line on the third microstrip arm. The wiring method of the corresponding anti-interference miniaturized microstrip mixer is diverse and can adapt to different line layout requirements, and at the same time is beneficial to improve the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0013] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and Doppler microwave detection module, wherein the lead-out position of the intermediate frequency output line 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 lead-out position of the intermediate frequency output line have equal electrical lengths, thereby avoiding the influence of the unequal electrical length connection between the first mixing port and the second mixing port and the corresponding mixing tube caused by errors in the production process of the bridge and the assembly process of the mixing tube on the Doppler intermediate frequency signal. 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 bridge and the assembly process of the mixing tube are reduced, so that it is simple, easy and low-cost.

[0014] One object of the present invention is to provide an anti-interference miniaturized microstrip mixer and a Doppler microwave detection module, wherein the anti-interference miniaturized microstrip mixer further comprises two pairs of ground pads, wherein the two pairs of ground pads are arranged in the area defined by the bridge and are respectively connected to the corresponding first mixing port and the second mixing port, which is beneficial to reduce the magnetic flux of the bridge in the magnetic field environment by occupying the area of ​​the area defined by the bridge, wherein the two ends of the two mixing tubes with different polarities belonging to different mixing tubes are respectively connected to the two pairs of ground pads and connected to the corresponding first mixing port and the second mixing port , so as to form a state in which the connection lines between the two mixing tubes and the first mixing port and the second mixing port are located within the area defined by the bridge, thereby reducing the space size occupied by the anti-interference miniaturized microstrip mixer, and being able to form a sudden angle change in the connection lines between the two mixing tubes and the first mixing port and the second mixing port in the extension direction of the second microstrip mixing arm and the fourth microstrip mixing arm, which is beneficial to suppress the transient electrical signal in the bridge while maintaining the mixing characteristics of the bridge, and correspondingly ensuring the feedback accuracy of the Doppler intermediate frequency signal on the movement of the object in the corresponding detection space.

[0015] Another object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and Doppler microwave detection module, wherein the transients of the electrical signals in the bridge are suppressed, and the requirements of the bridge on the high-frequency and low-loss characteristics of its carrier are reduced. Accordingly, the bridge is suitable for being carried by an ordinary circuit board substrate, which is beneficial for reducing the cost of the Doppler microwave detection module and simplifying 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.

[0016] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and a Doppler microwave detection module, wherein the high-frequency filtering characteristics of the high-frequency filtering circuit are improved based on the distributed capacitance formed between the ground pad and the ground, and the frequency selection characteristics of the interference-resistant miniaturized microstrip mixer are correspondingly improved, which is beneficial to improve the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0017] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and a Doppler microwave detection module, wherein the interference-resistant miniaturized microstrip mixer further includes a grounded ground pad, wherein the grounded ends of the two mixing tubes with different polarities belonging to different mixing tubes are grounded in a state of being connected to the ground pad.

[0018] One object of the present invention is to provide an anti-interference miniaturized microstrip mixer and Doppler microwave detection module, wherein the ground pad is arranged to be isolated from the two ground pads by the first microstrip arm and is located outside the area defined by the bridge, corresponding to the two ends with different polarities belonging to different mixing tubes in the two mixing tubes being respectively connected to the two ground pads, and the other two ends with different polarities belonging to different mixing tubes in the two mixing tubes being connected to the ground pad, forming an interlayer staggered relationship between the two mixing tubes and the bridge, thereby reducing the space size occupied by the anti-interference miniaturized microstrip mixer.

[0019] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and Doppler microwave detection module, wherein the first microstrip mixing arm is bent to form a concave in the boundary corresponding to the bridge at the first microstrip mixing arm, corresponding to the concave in the boundary corresponding to the first microstrip mixing arm of the area defined by the bridge, thereby reducing the area defined by the bridge, thereby facilitating further reducing the space size occupied by the interference-resistant miniaturized microstrip mixer, and reducing the magnetic flux of the bridge in the magnetic field environment to improve the anti-interference performance of the corresponding Doppler microwave detection module.

[0020] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and a Doppler microwave detection module, wherein the ground pad is arranged at the concave part of the boundary of the bridge corresponding to the first microstrip mixing arm and the two ground pads are isolated by the first microstrip arm, thereby facilitating reducing the size of the interference-resistant miniaturized microstrip mixer in the midline direction of the line connecting the first mixing port and the second mixing port.

[0021] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and a Doppler microwave detection module, wherein the interference-resistant miniaturized microstrip mixer further includes a microstrip line extending from the middle position of the first microstrip mixing arm to maintain the state of the mixing characteristics of the bridge while maintaining the phase difference between the first mixing port and the second mixing port, and based on the regulating effect of the microstrip line on the impedance matching of the bridge, the anti-interference performance of the interference-resistant miniaturized microstrip mixer is improved by satisfying the corresponding impedance matching.

[0022] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and Doppler microwave detection module, wherein the microstrip line led out from the middle position of the first microstrip mixing arm is extended to the middle position of the third microstrip mixing arm and connected to the third microstrip mixing arm, so as to form two mixing circuits with the microstrip line as a common route in the bridge, which is beneficial to the cancellation of interference signals generated by electromagnetic induction in the bridge and further improves the anti-interference performance of the interference-resistant miniaturized microstrip mixer.

[0023] One object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and Doppler microwave detection module, wherein the bridge 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 bridge, and thus it is easy to implement.

[0024] Another object of the present invention is to provide an interference-resistant miniaturized microstrip mixer and a Doppler microwave detection module, 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 interference-resistant miniaturized microstrip mixer, wherein the antenna is fed and connected to the feedback signal input port of the interference-resistant miniaturized microstrip mixer, so that the antenna can be fed with the local oscillator signal via the interference-resistant miniaturized microstrip mixer and input the feedback signal to the interference-resistant miniaturized microstrip mixer, correspondingly 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 interference-resistant miniaturized microstrip mixer.

[0025] According to one aspect of the present invention, the present invention provides an anti-interference miniaturized microstrip mixer, wherein the microstrip mixer is suitable for receiving a local oscillator signal and a feedback signal, and outputting 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, and the microstrip mixer comprises:

[0026] A bridge, wherein the bridge is arranged in a microstrip line form and has a local oscillator signal input port for inputting the local oscillator signal, a feedback signal input port for inputting the feedback signal, a first mixing port, a second mixing port, and a first microstrip arm connected between the local oscillator signal input port and the feedback signal input port, a second microstrip arm connected between the feedback signal input port and the first mixing port, a third microstrip arm connected between the first mixing port and the second mixing port, and a fourth microstrip arm connected between the second mixing port and the local oscillator signal input port, wherein the second microstrip arm and the fourth microstrip arm are arranged with equal lengths, wherein at an operating frequency of 5.8 GHz in the ISM band, with λ being an electrical length parameter of one wavelength corresponding to the operating frequency, the electrical length of the bridge is less than 0.9λ, wherein the electrical lengths of the second microstrip arm and the fourth microstrip arm are less than λ / 5, and the electrical length of the first microstrip arm is greater than or equal to λ / 8 and less than or equal to λ / 2;

[0027] 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;

[0028] An intermediate frequency output line, wherein the intermediate frequency output line is led out from the middle position of the third microstrip arm, and two sections corresponding to the third microstrip mixing arm with the lead-out position of the intermediate frequency output line as the boundary have equal electrical length within a 20% error range, so that the local oscillator signal is input into the local oscillator signal input port, and the feedback signal is input into the feedback signal input port, and the Doppler intermediate frequency signal is output on the intermediate frequency output line.

[0029] In one embodiment, when the local oscillator signal is input into the local oscillator signal input port or the feedback signal is input into the feedback signal input port, a phase difference between the first mixing port and the second mixing port ranges from 60 degrees to 120 degrees.

[0030] In one embodiment, the two mixing tubes are arranged in the form of diodes, and the connection structure in which the two ends of the two diodes with different polarities are respectively connected to the first mixing port and the second mixing port corresponds to that the anode of one of the diodes is connected to the first mixing port, and the cathode of the other diode is connected to the second mixing port.

[0031] In one embodiment, the anti-interference miniaturized microstrip mixer further includes two ground pads, wherein the two ground pads are arranged in the area defined by the bridge and are respectively connected to the corresponding first mixing port and the second mixing port, wherein the two ends with different polarities belonging to different mixing tubes in the two mixing tubes are connected to the corresponding first mixing port and the second mixing port in a state of being connected to the corresponding ground pads.

[0032] In one embodiment, the anti-interference miniaturized microstrip mixer further comprises a grounded ground pad, wherein the grounded ends of the two mixing tubes with different polarities belonging to different mixing tubes are grounded in a state of being connected to the ground pad.

[0033] In one embodiment, the ground pad is arranged to be isolated from the two ground pads by the first microstrip arm and located outside the area defined by the bridge, and the two ends with different polarities belonging to different mixers in the two mixers are respectively connected to the two ground pads, and the other two ends with different polarities belonging to different mixers in the two mixers are connected to the ground pad and grounded, thereby forming an interlayer staggered state between the two mixers and the bridge.

[0034] In one embodiment, the first microstrip mixing arm is bent to form a concave portion of the bridge corresponding to a boundary of the first microstrip mixing arm.

[0035] In one embodiment, the ground pad is arranged at the concave part of the boundary of the bridge corresponding to the first microstrip mixing arm and is isolated from the two ground pads by the first microstrip arm, and the corresponding ground pad is entirely or partially located in the concave space of the boundary of the bridge corresponding to the first microstrip mixing arm.

[0036] In one embodiment, the first mixing port and the second mixing port are connected to two ends of the two mixing tubes with different polarities and belonging to different mixing tubes with equal electrical lengths.

[0037] In one embodiment, the bridge is arranged symmetrically with respect to a midline of a line connecting the local oscillator signal input port and the feedback signal input port.

[0038] In one embodiment, the bridge is carried on a FR4 board with a thickness of 0.6 mm.

[0039] In one embodiment, the anti-interference miniaturized microstrip mixer further includes a microstrip line extending from a middle position of the first microstrip mixing arm, and two sections of the first microstrip mixing arm bounded by the lead-out position of the microstrip line have equal electrical lengths within a 20% error range.

[0040] In one embodiment, the microstrip line extending from the middle position of the first microstrip mixing arm is extended to the middle position of the third microstrip mixing arm and connected to the third microstrip mixing arm, so as to form two mixing loops in the bridge with the microstrip line as a common route.

[0041] In one embodiment, the third microstrip mixing arm is bent to form a structural state in which a middle position of the third microstrip mixing arm is directly connected to a middle position of the first microstrip mixing arm.

[0042] According to another aspect of the present invention, the present invention 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 generate a feedback signal in an electromagnetic environment; and

[0045] An anti-interference miniaturized microstrip mixer, wherein the anti-interference miniaturized microstrip mixer comprises:

[0046] A bridge, wherein the bridge is arranged in a microstrip line form and has a local oscillator signal input port suitable for inputting the local oscillator signal, a feedback signal input port suitable for inputting the feedback signal, a first mixing port, a second mixing port, and a first microstrip arm connected between the local oscillator signal input port and the feedback signal input port, a second microstrip arm connected between the feedback signal input port and the first mixing port, a third microstrip arm connected between the first mixing port and the second mixing port, and a fourth microstrip arm connected between the second mixing port and the local oscillator signal input port, wherein the second microstrip arm and the fourth microstrip arm are connected An equal length arrangement, wherein at an operating frequency of 5.8 GHz in the ISM frequency band, with λ being an electrical length parameter of one wavelength corresponding to the operating frequency, the electrical length of the bridge is less than 0.9λ, wherein the electrical lengths of the second microstrip arm and the fourth microstrip arm are less than λ / 5, and the electrical length of the first microstrip arm is greater than or equal to λ / 8 and less than or equal to λ / 2, wherein the local oscillator signal input port is fed and connected to the local oscillator circuit and the local oscillator signal is connected when 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 anti-interference miniaturized microstrip mixer;

[0047] 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;

[0048] an intermediate frequency output line, wherein the intermediate frequency output line is led out from the middle position of the third microstrip arm, and two sections corresponding to the lead-out position of the intermediate frequency output line on the third microstrip mixing arm have equal electrical lengths within a 20% error range, 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 on the intermediate frequency output line.

[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 anti-interference miniaturized microstrip mixer further includes two ground pads, wherein the two ground pads are arranged in the area defined by the bridge and are respectively connected to the corresponding first mixing port and the second mixing port, wherein the two ends with different polarities belonging to different mixing tubes in the two mixing tubes are connected to the corresponding first mixing port and the second mixing port in a state of being connected to the corresponding ground pads.

[0051] In one embodiment, the anti-interference miniaturized microstrip mixer further comprises a ground pad, wherein the ground pad is connected to the reference ground and grounded, wherein the grounded ends of the two mixing tubes with different polarities belonging to different mixing tubes are grounded in a state of being connected to the ground pad.

[0052] In one embodiment, the ground pad is arranged to be isolated from the two ground pads by the first microstrip arm and located outside the area defined by the bridge, and the two ends with different polarities belonging to different mixers in the two mixers are respectively connected to the two ground pads, and the other two ends with different polarities belonging to different mixers in the two mixers are connected to the ground pad and grounded, thereby forming an interlayer staggered state between the two mixers and the bridge.

[0053] In one embodiment, the first microstrip mixing arm is bent to form a concave portion of the bridge corresponding to a boundary of the first microstrip mixing arm.

[0054] In one embodiment, the ground pad is arranged at the concave part of the boundary of the bridge corresponding to the first microstrip mixing arm and is isolated from the two ground pads by the first microstrip arm, and the corresponding ground pad is entirely or partially located in the concave space of the boundary of the bridge corresponding to the first microstrip mixing arm.

[0055] Further objects and advantages of the present invention will be fully apparent from an understanding of the following description and the accompanying drawings.

[0056] 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

[0057] Figure 1A Schematic diagram of the equivalent circuit principle of an existing balanced mixer.

[0058] Figure 1B 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.

[0059] Figure 2AFIG. 1 is a schematic diagram of an equivalent circuit principle of an anti-interference miniaturized microstrip mixer according to an embodiment of the present invention.

[0060] Figure 2B A schematic diagram of an equivalent circuit principle of a further variant of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0061] Figure 3 Schematic diagram of a microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0062] Figure 4 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0063] Figure 5 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0064] Figure 6 1 and 2 are mixing characteristic curves of the three microstrip structures of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0065] Figure 7 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0066] Figure 8 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0067] Fig. 9 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0068] Fig.10 1 and 2 are mixing characteristic curves of the three microstrip structures of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0069] Fig.11 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0070] Fig.12 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0071] Fig.13 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0072] Fig.14 1 and 2 are mixing characteristic curves of the three microstrip structures of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0073] Fig.15 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0074] Fig.16 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0075] Fig.17 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0076] Fig.18 1 and 2 are mixing characteristic curves of the three microstrip structures of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0077] Fig.19 FIG. 2 is another schematic diagram of an equivalent circuit principle of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0078] Fig. 20A Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0079] Fig. 20B FIG. 1 is a mixing characteristic curve of the microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0080] Fig.21 Schematic diagram of another microstrip structure of the anti-interference miniaturized microstrip mixer according to the above embodiment of the present invention.

[0081] Fig.22A FIG. 4 is a schematic diagram of an equivalent circuit principle of a Doppler microwave detection module according to an embodiment of the present invention.

[0082] Fig. 22B It is a schematic diagram of an equivalent circuit principle of a further modified anti-Doppler microwave detection module according to the above embodiment of the present invention. DETAILED DESCRIPTION

[0083] 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.

[0084] 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.

[0085] 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.

[0086] The present invention provides an interference-resistant miniaturized microstrip mixer and a Doppler microwave detection module, wherein the Doppler microwave detection module is suitable for being fed by a local oscillator signal through the interference-resistant miniaturized 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 generate a feedback signal, wherein the interference-resistant miniaturized microstrip 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, then based on the principle of the Doppler effect, the fluctuation in the amplitude of the Doppler intermediate frequency signal theoretically corresponds to the movement of the object in the detection space.

[0087] Referring to the accompanying drawings of the present invention Figures 2A to 18As shown, the equivalent circuit principle of the anti-interference miniaturized microstrip mixer of the present invention and the structure and mixing characteristics of the anti-interference miniaturized microstrip mixer according to different embodiments based on the equivalent circuit principle are respectively illustrated, wherein the anti-interference miniaturized microstrip mixer comprises a bridge 10, two mixing tubes 20 and an intermediate frequency output line 30, wherein the bridge 10 is arranged in the form of a microstrip line and has a local oscillator signal input port 101 suitable for inputting the local oscillator signal, a feedback signal input port 102 suitable for inputting the feedback signal, a first mixing port 103, a second mixing port 104, and a first microstrip arm 11 connected between the local oscillator signal input port 101 and the feedback signal input port 102, a second microstrip arm 12 connected between the feedback signal input port 102 and the first mixing port 103, a third microstrip arm 13 connected between the first mixing port 103 and the second mixing port 104, a third microstrip arm 14 connected between the second mixing port 104 and the local oscillator signal input port 101, and a third microstrip arm 15 connected between the second mixing port 104 and the local oscillator signal input port 102. A fourth microstrip arm 14 between the inlet 101, wherein the second microstrip arm 12 and the fourth microstrip arm 14 are set to be of equal length, wherein based on an operating frequency of the ISM band of 5.8 GHz, with λ being an electrical length parameter of one wavelength corresponding to the operating frequency, the electrical length of the bridge 10 is shortened to less than 0.9λ by shortening the electrical lengths of the second microstrip arm 12 and the fourth microstrip arm 14 to less than λ / 5, respectively, relative to the existing balanced mixer, and in a state where the electrical length of the bridge 10 is less than 0.9λ, within an electrical length range of greater than or equal to λ / 8 and less than or equal to λ / 2, based on the corresponding length and shape of the first microstrip arm 11, when the local oscillator signal is input to the local oscillator signal input port 101, or the feedback signal is input to the feedback signal input port 102, a phase difference of 60 degrees to 120 degrees can still be formed between the first mixing port 103 and the second mixing port 104, thereby shortening the electrical length of the bridge 10 to less than 0.9λ state, maintaining the mixing characteristics of the bridge; wherein the intermediate frequency output line 30 is led out from the third microstrip arm 13, 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 103 and the second mixing port 104, and the other two ends of the two mixing tubes 20 with different polarities belonging to different mixing tubes 20 are grounded to ensure that the two ends are short-circuited to the ground at high frequency and form a first mixing port 103 and a second mixing port 104 between the first mixing port 103 and the second mixing port 104. The high-frequency filter circuit formed by the grounded line of the tube 20 and the second mixer port 104 through another grounded line of the mixer 20, so that the power of the local oscillator signal and the feedback signal respectively input from the local oscillator signal input port 101 and the feedback signal input port 102 can be fully loaded on the two mixer tubes 20 without leaking to the intermediate frequency output line 30, thereby ensuring the output power and anti-interference performance of the Doppler intermediate frequency signal output from the intermediate frequency output line 30, which is conducive to improving the feedback accuracy of the Doppler intermediate frequency signal on the movement of the object in the corresponding detection space.

[0088] Specifically, in these embodiments of the present invention, the two mixing tubes 20 are arranged in the form of diodes, and the connection structure in which the two ends of the two diodes with different polarities belonging to different diodes are respectively connected to the first mixing port 103 and the second mixing port 104 preferably corresponds to: the positive electrode of one of the diodes is connected to the first mixing port 103, and the negative electrode of the other diode is connected to the second mixing port 104, which is beneficial to improve the mixing efficiency of the anti-interference miniaturized microstrip mixer.

[0089] It is worth mentioning that the electrical length of the bridge 10 is less than 0.9λ, and the corresponding signal frequency that can resonate with the bridge is greater than 5.8GHz / 0.9=6.4GHz, so that the bridge 10 can leave the resonance state at the operating frequency. The radiation and receiving capabilities of the bridge 10 for the signal corresponding to the operating frequency are reduced, thereby ensuring the output power and anti-interference performance of the Doppler intermediate frequency signal, and correspondingly improving the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0090] In addition, the electrical length of the bridge 10 is less than 0.9λ, and the corresponding signal frequency that can generate resonance in the bridge is greater than 5.8GHz / 0.9=6.4GHz and is outside 1GHz-6GHz. Then, the radiation immunity test based on the IEC61000-4-3 / GB T 17626.3 standard is difficult to produce an amplitude change in the Doppler intermediate frequency signal that exceeds the standard limit. Accordingly, the pass rate of the Doppler microwave detection module in the radiation immunity test of the IEC61000-4-3 / GB T 17626.3 standard is improved, which is beneficial to the promotion of the Doppler microwave detection module and the improvement of commercial competitiveness in the field of Doppler microwave detection.

[0091] Furthermore, the electrical length of the bridge 10 is less than 0.9λ, which is beneficial to reducing the area defined by the bridge 10 relative to the existing balanced mixer, and thus is beneficial to the adaptability of the bridge 10 to the circuit layout of the corresponding Doppler microwave detection module of the miniaturized design, which is beneficial to the miniaturized design of the Doppler microwave detection module and improves the commercial competitiveness of the Doppler microwave detection module in accordance with the miniaturization trend. At the same time, the area defined by the bridge 10 is reduced, which can reduce the magnetic flux of the bridge 10 in the magnetic field environment, and correspondingly reduce the energy of the interference signal generated by the bridge 10 in the magnetic field environment based on electromagnetic induction, and thus is beneficial to further improve the anti-interference performance of the Doppler microwave detection module and improve the feedback accuracy of the Doppler intermediate frequency signal on the movement of the object in the corresponding detection space.

[0092] Specifically, in these embodiments of the present invention, the first mixing port 103 and the second mixing port 104 are connected to two ends of the two mixing tubes 20 with different polarities and belonging to different mixing tubes 20 with 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 limitation of the lead-out position of the intermediate frequency output line 30 in the third microstrip arm 13. The wiring methods of the corresponding anti-interference miniaturized 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.

[0093] Preferably, the lead-out position of the intermediate frequency output line 30 is located in the middle position of the third microstrip mixing arm 13, and the two sections on the third microstrip mixing arm 13 bounded by the lead-out position of the intermediate frequency output line 30 have equal electrical lengths, so as to avoid the influence of the non-equal electrical length connection between the first mixing port 103 and the second mixing port 104 and the corresponding mixing tube 20 caused by errors in the production process of the bridge 10 and the assembly process of the mixing tube 20 on the Doppler intermediate frequency signal. 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 bridge 10 and the assembly process of the mixing tube 20 are reduced, so it is simple, easy and low-cost.

[0094] Further, the anti-interference miniaturized microstrip mixer also includes two ground pads 40, wherein the two ground pads 40 are arranged in the area defined by the bridge 10 and are respectively connected to the corresponding first mixing port 103 and the second mixing port 104, including but not limited to a connection method of connecting to the corresponding first mixing port 103 and the second mixing port 104 through part of the third microstrip arm 103, wherein the two ends with different polarities belonging to different mixing tubes 20 in the two mixing tubes 20 are respectively connected to the two ground pads 40 and connected to the corresponding first mixing port 103 and the second mixing port 104. 04 are connected, so as to form a state in which the connection lines between the two mixing tubes 20 and the first mixing port 103 and the second mixing port 104 are located in the area defined by the bridge 10, which is beneficial to reducing the space size occupied by the anti-interference miniaturized microstrip mixer to realize the miniaturized design of the anti-interference miniaturized microstrip mixer, and reducing the magnetic flux of the bridge 10 in the magnetic field environment by occupying the area defined by the bridge 10, correspondingly reducing the energy of the interference signal generated by the bridge 10 in the magnetic field environment based on electromagnetic induction, thereby improving the anti-interference performance of the anti-interference miniaturized microstrip mixer.

[0095] It is worth mentioning that, in a state where the two ground pads 40 are arranged in the area defined by the bridge 10 and are respectively connected to the corresponding first mixing port 103 and the second mixing port 104, when the two ends of the two mixing tubes 20 with different polarities belonging to different mixing tubes 20 are respectively connected to the two ground pads 40 and connected to the corresponding first mixing port 103 and the second mixing port 104, the angle mutation amount of the connection line between the two mixing tubes 20 and the first mixing port 103 and the second mixing port 104 in the extension direction of the second microstrip mixing arm 12 and the fourth microstrip mixing arm 14 is increased, which is beneficial to suppress the transient electrical signal in the bridge 10 while maintaining the mixing characteristics of the bridge 10, and correspondingly ensure the feedback accuracy of the Doppler intermediate frequency signal to the movement of the object in the corresponding detection space.

[0096] In addition, the transient of the electrical signal in the bridge 10 can be suppressed, so the requirements of the bridge 10 on the high-frequency and low-loss characteristics of its carrier are reduced. Accordingly, the bridge 10 is suitable for being carried by an ordinary circuit board substrate. This 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.

[0097] In particular, based on the setting of the ground pad 40, the ground pad 40 can form a distributed capacitance C between the ground and the high-frequency filtering circuit to improve the high-frequency filtering characteristics, which correspondingly improves the frequency selection characteristics of the anti-interference miniaturized microstrip mixer and is beneficial to further improve the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0098] Furthermore, in these embodiments of the present invention, the anti-interference miniaturized microstrip mixer also includes a grounded ground pad 50, wherein the grounded two ends with different polarities belonging to different mixing tubes 20 of the two mixing tubes 20 are grounded in a state of being connected to the ground pad 50.

[0099] Specifically, the ground pad 50 is arranged to be isolated from the two ground pads 40 by the first microstrip arm 11 and is located outside the area defined by the bridge 10, corresponding to the two ends with different polarities belonging to different mixing tubes 20 in the two mixing tubes 20 are respectively connected to the two ground pads 40, and the other two ends with different polarities belonging to different mixing tubes 20 in the two mixing tubes 20 are connected to the ground pad 50, forming an interlayer staggered relationship between the two mixing tubes 20 and the bridge 10, thereby reducing the space size occupied by the anti-interference miniaturized microstrip mixer.

[0100] Furthermore, in these embodiments of the present invention, the first microstrip mixing arm 11 is bent to form a concave portion of the bridge 10 at the boundary corresponding to the first microstrip mixing arm 11, that is, a concave portion of the area defined by the bridge 10 at the boundary corresponding to the first microstrip mixing arm 11 is formed, thereby reducing the area of ​​the area defined by the bridge 10, thereby facilitating further reducing the space size occupied by the anti-interference miniaturized microstrip mixer, and reducing the magnetic flux of the bridge in the magnetic field environment, thereby improving the anti-interference performance of the corresponding Doppler microwave detection module.

[0101] In particular, in these embodiments of the present invention, the ground pad 50 is arranged at the concave part of the boundary of the bridge 10 corresponding to the first microstrip mixing arm 11 and is isolated from the two ground pads 40 by the first microstrip arm 11, that is, the ground pad 50 is completely or partially located in the concave space of the boundary of the bridge 10 corresponding to the first microstrip mixing arm 11, which is beneficial to reducing the size of the anti-interference miniaturized microstrip mixer in the centerline direction of the line connecting the first mixing port 103 and the second mixing port 104.

[0102] Preferably, in these embodiments of the present invention, the bridge 10 is arranged to be symmetrical with respect to the midline of the line connecting the local oscillator signal input port 101 and the feedback signal input port 102, so that the electrical length relationship between the microstrip mixing arms can be satisfied based on a simple form design of the bridge 10, and thus it is easy to implement.

[0103] Further, corresponding to Figure 4 , Figure 5 , Figure 8 , Fig. 9 , Fig.12 , Fig.13 , Fig.16 as well as Fig.17 In these embodiments of the present invention, the anti-interference miniaturized microstrip mixer further includes a microstrip line 60 extending from the middle position of the first microstrip mixing arm 11 to maintain the mixing characteristics of the bridge 10 while maintaining the phase difference between the first mixing port 103 and the second mixing port 104. The length and shape of the microstrip line 60 are designed to adjust the impedance matching of the bridge 10, thereby satisfying the corresponding impedance matching to improve the anti-interference performance of the anti-interference miniaturized microstrip mixer.

[0104] In particular, corresponding to Figure 5 , Fig. 9 , Fig.13 ,as well as Fig.17In these embodiments of the present invention, the microstrip line 60 led out from the middle position of the first microstrip mixing arm 11 is extended to the middle position of the third microstrip mixing arm 13 and connected to the third microstrip mixing arm 13, so as to form two mixing circuits with the microstrip line 60 as a common route in the bridge 10, which is beneficial to the cancellation of interference signals generated by electromagnetic induction in the bridge 10 and further improves the anti-interference performance of the anti-interference miniaturized microstrip mixer.

[0105] Further reference is made to the accompanying drawings of the present invention. Figure 6 As shown, taking the circuit board substrate carrying the bridge 10 as an example, which is a 0.6mm thick FR4 board, the physical length corresponding to the electrical length of one wavelength in the 5.8GHz ISM band is approximately 28.4mm, corresponding to Figures 3 to 5 The phase difference between the first mixer port 103 and the second mixer port 104 of the bridge 10 as a function of the input frequency of the local oscillator signal input port 101 is shown, where at a frequency of 5.8 GHz, the phase difference between the first mixer port 103 and the second mixer port 104 is approximately 92.5 degrees, corresponding to Figures 3 to 5 In the illustrated bridge 10 , the actual physical length of the bridge 10 is 17.3 mm, corresponding to an electrical length of 0.61λ.

[0106] Referring to the accompanying drawings of the present invention Fig.10 As shown, the circuit board substrate carrying the bridge 10 is also taken as an example of a 0.6mm thick FR4 board, corresponding to Figures 7 to 9 The phase difference between the first mixer port 103 and the second mixer port 104 of the bridge 10 as a function of the input frequency of the local oscillator signal input port 101 is shown, where at a frequency of 5.8 GHz, the phase difference between the first mixer port 103 and the second mixer port 104 is approximately 104 degrees, corresponding to Figures 7 to 9 In the illustrated bridge 10 , the actual physical length of the bridge 10 is 19.8 mm, corresponding to an electrical length of 0.7λ.

[0107] Referring to the accompanying drawings of the present invention Fig.14 As shown, the circuit board substrate carrying the bridge 10 is also taken as an example of a 0.6mm thick FR4 board, corresponding to Figures 11 to 13 The phase difference between the first mixer port 103 and the second mixer port 104 of the bridge 10 as a function of the input frequency of the local oscillator signal input port 101 is shown, where at a frequency of 5.8 GHz, the phase difference between the first mixer port 103 and the second mixer port 104 is approximately 102.5 degrees, corresponding to Figures 11 to 13In the illustrated bridge 10 , the actual physical length of the bridge 10 is 21.7 mm, corresponding to 0.764λ.

[0108] Referring to the accompanying drawings of the present invention Fig.18 As shown, the circuit board substrate carrying the bridge 10 is also taken as an example of a 0.6mm thick FR4 board, corresponding to Figures 15 to 17 The phase difference between the first mixer port 103 and the second mixer port 104 of the bridge 10 as a function of the input frequency of the local oscillator signal input port 101 is shown, where at a frequency of 5.8 GHz, the phase difference between the first mixer port 103 and the second mixer port 104 is approximately 100.4 degrees, corresponding to Figures 15 to 17 In the illustrated bridge 10 , the actual physical length of the bridge 10 is 24.2 mm, corresponding to 0.852λ.

[0109] It is worth mentioning that in these embodiments of the present invention, the two ground pads 40 are arranged in the area defined by the bridge 10 and are respectively connected to the corresponding first mixing port 103 and the second mixing port 104, including but not limited to the connection method of connecting to the corresponding first mixing port 103 and the second mixing port 104 through part of the third microstrip arm 103, wherein the connection line between the ground pad 40 and the first mixing port 103 and the second mixing port 104 has an inductance characteristic under the action of a high-frequency electrical signal and is equivalent to Fig.19 The equivalent inductance L shown in the figure allows the shape design of the connection line between the ground pad 40 and the first mixing port 103 and the second mixing port 104, and / or the way of connecting inductance elements in series in the connection line, so that the distributed capacitance C formed between the ground pad 40 and the ground can work together with the equivalent inductance L to improve the high-frequency filtering characteristics of the high-frequency filtering circuit, correspondingly improve the frequency selection characteristics of the anti-interference miniaturized microstrip mixer, which is beneficial to further improve the feedback accuracy of the Doppler intermediate frequency signal on the movement of objects in the corresponding detection space.

[0110] That is, based on the inductance characteristics of the connection lines between the ground pad 40 and the first mixing port 103 and the second mixing port 104 under the action of high-frequency electrical signals, the equivalent circuit principles of these embodiments of the present invention are Figure 2A Based on the shape design of the connection line between the ground pad 40 and the first mixing port 103 and the second mixing port 104, and / or the way of connecting the inductor element in series in the connection line, corresponding to Fig.19The equivalent inductance L is further provided between the ground pad 40 and the first mixing port 103 and the second mixing port 104 .

[0111] Further, referring to the accompanying drawings of the present invention, Fig. 20A and Fig. 20B , in a state where the microstrip line 60 led out from the middle position of the first microstrip mixing arm 11 is extended to the middle position of the third microstrip mixing arm 13 and connected to the third microstrip mixing arm 13, the structure and mixing characteristics of the anti-interference miniaturized microstrip mixer according to another embodiment of the above-mentioned equivalent circuit principle of the present invention are respectively illustrated, wherein in this embodiment of the present invention, based on the bending of the third microstrip mixing arm 13, the middle position of the first microstrip mixing arm 11 is directly connected to the middle position of the third microstrip mixing arm 13 to equivalently replace the structural state in which the middle position of the first microstrip mixing arm 11 is connected to the middle position of the third microstrip mixing arm 13 via the microstrip line 60.

[0112] Taking the circuit board substrate carrying the bridge 10 as an example, the FR4 board with a thickness of 0.6 mm corresponds to Fig. 20A The phase curves of the first mixer port 103 and the second mixer port 104 of the bridge 10 as a function of the input frequency of the local oscillator signal input port 101 are shown in FIG. Fig. 20B As shown, at a frequency of 5.8 GHz, the phase difference between the first mixing port 103 and the second mixing port 104 is about 94.7 degrees, corresponding to Fig. 20A In the illustrated bridge 10 , the actual physical length of the bridge 10 is 18.6 mm, corresponding to 0.66λ.

[0113] It is worth mentioning that the above embodiments are only examples, in which the second microstrip arm 12 and the fourth microstrip arm 14 are set to be of equal length within the electrical length range of less than λ / 5, and the electrical length of the bridge 10 is less than 0.9λ. In order to satisfy the phase difference of 60 to 120 degrees between the first mixing port 103 and the second mixing port 104, the first microstrip arm 11 has a variety of morphological settings within the electrical length range of greater than or equal to λ / 8 and less than or equal to λ / 2, and the third microstrip arm 13 also has a variety of adaptive electrical length and morphological settings, and the present invention is not limited to this.

[0114] For example, in some other embodiments of the present invention, corresponding to Fig.21 ,exist Fig. 20AOn the basis of the structure of the anti-interference miniaturized microstrip mixer shown in the figure, it is also possible to form a concave in the boundary of the bridge 10 corresponding to the first microstrip mixing arm 11 based on the bending or shape setting of the first microstrip mixing arm 11, and further form a concave in the boundary of the area defined by the bridge 10 corresponding to the first microstrip mixing arm 11, thereby reducing the area of ​​the area defined by the bridge 10, thereby facilitating further reducing the space size occupied by the anti-interference miniaturized microstrip mixer, and reducing the magnetic flux of the bridge in the magnetic field environment to improve the anti-interference performance of the corresponding Doppler microwave detection module.

[0115] In addition, due to the existence of production and test errors, in the above description, the relationship description and limitation based on the electrical length are allowed to have an error range of 20% in actual measurement.

[0116] Further reference is made to the accompanying drawings of the present invention. Fig.22A and Fig. 22B , the equivalent circuit principle of the Doppler microwave detection module with the anti-interference miniaturized microstrip mixer is illustrated, wherein the Doppler microwave detection module further includes a local oscillator circuit 70 and an antenna 80, wherein the local oscillator circuit 70 is configured to allow being powered to output the local oscillator signal, and is fed to the local oscillator signal input port 101 of the anti-interference miniaturized microstrip mixer, wherein the antenna 80 is fed to the feedback signal input port 102 of the anti-interference miniaturized microstrip mixer, so that the antenna 80 can be fed with the local oscillator signal through the anti-interference miniaturized microstrip mixer and input the feedback signal to the anti-interference miniaturized microstrip mixer, correspondingly based on the above-mentioned structural principle of the anti-interference miniaturized microstrip mixer, the detection accuracy of the Doppler microwave detection module for the movement of objects in the corresponding detection space is improved.

[0117] It is worth mentioning that the feeding connection between the local oscillator circuit 70 and the local oscillator signal input port 101 of the anti-interference miniaturized microstrip mixer, and the feeding connection between the antenna 80 and the feedback signal input port 102 of the anti-interference miniaturized microstrip mixer are path connections under the action of high-frequency electrical signals. Therefore, the feeding connection between the local oscillator circuit 70 and the local oscillator signal input port 101 of the anti-interference miniaturized microstrip mixer, and the feeding connection between the antenna 80 and the feedback signal input port 102 of the anti-interference miniaturized 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.

[0118] Preferably, the feeding connection between the antenna 80 and the feedback signal input port 102 of the anti-interference miniaturized 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.

[0119] Optionally, the feeding connection between the local oscillator circuit 70 and the local oscillator signal input port 101 of the anti-interference miniaturized 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.

[0120] Furthermore, the antenna 80 includes a reference ground and a radiation source spaced from the reference ground to equivalently form an open capacitor C 0 The feedback signal can be generated in an electromagnetic environment, wherein the radiation source is fed to the feedback signal input port 102 of the anti-interference miniaturized microstrip mixer to form a feeding connection relationship between the antenna 80 and the feedback signal input port 102, wherein the reference ground is grounded and is equivalent to Fig.22A and Fig. 22B Equivalent capacitance C 0 The grounded level corresponds to the radiation source being equivalent to Fig.22A and Fig. 22B Medium open capacitor C 0 The other pole of the device, wherein the ground pad 50 is grounded in a state of being connected to the reference ground, and at the same time, the ground pad 40 can form a distributed capacitance C with the reference ground to improve the high-frequency filtering characteristics of the high-frequency filtering circuit.

[0121] 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.

[0122] 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. An anti-interference miniaturized microstrip mixer, wherein the microstrip mixer is adapted to receive a local oscillator signal and a feedback signal, and outputs a Doppler intermediate frequency signal corresponding to the frequency / phase difference between the local oscillator signal and the feedback signal in a mixing and detection manner. Characterized in that: It includes: A bridge, wherein the bridge is arranged in the form of a microstrip line and has a local oscillator signal input port adapted for the input of the local oscillator signal, a feedback signal input port adapted for the input of the feedback signal, a first mixing port, a second mixing port, and a first microstrip arm connected between the local oscillator signal input port and the feedback signal input port, a second microstrip arm connected between the feedback signal input port and the first mixing port, a third microstrip arm connected between the first mixing port and the second mixing port, and a fourth microstrip arm connected between the second mixing port and the local oscillator signal input port. The second microstrip arm and the fourth microstrip arm are arranged to be of equal length. At the operating frequency in the 5.8 GHz ISM band, with λ being the electrical length parameter corresponding to one wavelength of the operating frequency, the electrical length of the bridge is less than 0.9λ, the electrical lengths of the second microstrip arm and the fourth microstrip arm are less than λ / 5, and the electrical length of the first microstrip arm is greater than or equal to λ / 8 and less than or equal to λ / 2; Two mixing tubes, wherein two ends with different polarities belonging to different mixing tubes among 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 among the two mixing tubes are grounded; Two pairs of ground pads, wherein the two ground pads are respectively connected to the corresponding first mixing port and the second mixing port. Two ends with different polarities belonging to different mixing tubes among the two mixing tubes are connected to the corresponding first mixing port and the second mixing port in a state of being connected to the corresponding ground pads. The two mixing tubes and the two ground pads are all arranged within the area defined by the bridge, and; An intermediate frequency output line, wherein the intermediate frequency output line is led out from the middle position of the third microstrip arm. The two segments of the third microstrip arm corresponding to the leading-out position of the intermediate frequency output line have equal electrical lengths within an error range of 20%. In the state where 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, the Doppler intermediate frequency signal is output from the intermediate frequency output line.

2. The anti-interference miniaturized microstrip mixer according to claim 1, wherein in the state where the local oscillator signal is input to the local oscillator signal input port or the feedback signal is input to the feedback signal input port, there is a phase difference in the range of 60 degrees to 120 degrees between the first mixing port and the second mixing port.

3. The anti-interference miniaturized microstrip mixer according to claim 2, wherein the two mixing tubes are arranged in the form of diodes, and the connection structure in which the two ends with different polarities belonging to different diodes are respectively connected to the first mixing port and the second mixing port corresponds to the positive electrode of one diode being connected to the first mixing port and the negative electrode of the other diode being connected to the second mixing port.

4. The anti-interference miniaturized microstrip mixer according to claim 3, wherein the anti-interference miniaturized microstrip mixer further includes a ground pad grounded, and the two grounded ends with different polarities belonging to different mixing tubes are grounded in a state of being connected to the ground pad.

5. The anti-interference miniaturized microstrip mixer according to claim 4, wherein the ground pad is arranged to be isolated from the two ground pads by the first microstrip arm and is located outside the area defined by the bridge. Corresponding to the state where the two ends with different polarities belonging to different mixing tubes are respectively connected to the two ground pads, and the other two ends with different polarities belonging to different mixing tubes are connected to the ground pad and grounded, an interlayer stagger between the two mixing tubes and the bridge is formed.

6. The anti-interference miniaturized microstrip mixer according to claim 5, wherein the first microstrip arm is bent to form a concave portion corresponding to the boundary of the first microstrip arm of the bridge.

7. The anti-interference miniaturized microstrip mixer according to claim 6, wherein the ground pad is arranged at the concave portion corresponding to the boundary of the first microstrip arm of the bridge and is isolated from the two ground pads by the first microstrip arm. Corresponding to the ground pad being wholly or partially located in the concave space corresponding to the boundary of the first microstrip arm of the bridge.

8. The anti-interference miniaturized microstrip mixer according to claim 7, wherein the first mixing port and the second mixing port are connected with equal electrical lengths to the two ends with different polarities belonging to different mixing tubes.

9. The anti-interference miniaturized microstrip mixer according to claim 8, wherein the bridge is arranged symmetrically about the midline of the connection line between the local oscillator signal input port and the feedback signal input port.

10. The anti-interference miniaturized microstrip mixer according to claim 9, wherein the bridge is carried on an FR4 board with a thickness specification of 0.6 mm.

11. The anti-interference miniaturized microstrip mixer according to any one of claims 1 to 10, wherein the anti-interference miniaturized microstrip mixer further includes a microstrip line led out from the middle position of the first microstrip arm. Corresponding to the two segments of the first microstrip arm bounded by the leading-out position of the microstrip line having equal electrical lengths within an error range of 20%.

12. The anti-interference miniaturized microstrip mixer according to claim 11, wherein the microstrip line led out from the middle position of the first microstrip arm is extended to be connected to the middle position of the third microstrip arm to form two mixing circuits with the microstrip line as the common path in the bridge.

13. The anti-interference miniaturized microstrip mixer according to any one of claims 1 to 10, wherein the third microstrip arm is bent to form a structural state in which the middle position of the third microstrip arm is directly connected to the middle position of the first microstrip arm.

14. A Doppler microwave detection module Characterized in that Comprising: A local oscillator circuit, wherein the local oscillator circuit is arranged to be powered to output a local oscillator signal; An antenna, wherein the antenna includes a reference ground and a radiation source spaced from the reference ground to equivalently form an open capacitor capable of generating a feedback signal in an electromagnetic environment; And An anti-interference miniaturized microstrip mixer, wherein the anti-interference miniaturized microstrip mixer includes: A bridge, wherein the bridge is arranged in the form of a microstrip line and has a local oscillator signal input port suitable for input of the local oscillator signal, a feedback signal input port suitable for input of the feedback signal, a first mixing port, a second mixing port, and a first microstrip arm connected between the local oscillator signal input port and the feedback signal input port, a second microstrip arm connected between the feedback signal input port and the first mixing port, a third microstrip arm connected between the first mixing port and the second mixing port, and a fourth microstrip arm connected between the second mixing port and the local oscillator signal input port, wherein the second microstrip arm and the fourth microstrip arm are arranged to be of equal length, wherein at the operating frequency of the 5.8 GHz ISM band, with λ being the electrical length parameter of a single wavelength corresponding to the operating frequency, the electrical length of the bridge is less than 0.9λ, wherein the electrical lengths of the second microstrip arm and the fourth microstrip arm are less than λ / 5, the electrical length of the first microstrip arm is greater than or equal to λ / 8 and less than or equal to λ / 2, wherein the local oscillator signal input port is fed and connected to the local oscillator circuit to access the local oscillator signal in the state where the local oscillator circuit is powered, and wherein the radiation source is fed and connected to the feedback signal input port to be fed by the local oscillator signal and input the feedback signal to the anti-interference miniaturized microstrip mixer; Two mixing tubes, wherein two ends with different polarities belonging to different mixing tubes among 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 among the two mixing tubes are grounded; Two pairs of ground pads, wherein the two ground pads are respectively connected to the corresponding first mixing port and the second mixing port, and two ends with different polarities belonging to different ones of the two mixing tubes are connected to the corresponding first mixing port and the second mixing port in a state of being connected to the corresponding ground pads, and the two mixing tubes and the two ground pads are all arranged within the region defined by the bridge, and; An intermediate frequency output line, wherein the intermediate frequency output line is led out from the middle position of the third microstrip arm, and the two segments of the third microstrip arm bounded by the leading-out position of the intermediate frequency output line have equal electrical lengths within an error range of 20%. In a state where 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 on the intermediate frequency output line.

15. The Doppler microwave detection module according to claim 14, wherein the feeding connection between the radiation source and the feedback signal input port is in a form of an open connection capacitively coupled through a corresponding capacitor in the physical circuit.

16. The Doppler microwave detection module according to claim 15, wherein the anti-interference miniaturized microstrip mixer further includes a ground pad, wherein the ground pad is connected to the reference ground and grounded, and two grounded ends with different polarities belonging to different ones of the two mixing tubes are grounded in a state of being connected to the ground pad.

17. The Doppler microwave detection module according to claim 16, wherein the ground pad is arranged to be isolated from the two ground pads by the first microstrip arm and is located outside the region defined by the bridge. Corresponding to the state where two ends with different polarities belonging to different ones of the two mixing tubes are respectively connected to the two ground pads, and the other two ends with different polarities belonging to different ones of the two mixing tubes are connected to the ground pad and grounded, an interlayer stagger between the two mixing tubes and the bridge is formed.

18. The Doppler microwave detection module according to claim 17, wherein the first microstrip arm is bent to form an inward concavity corresponding to the boundary of the first microstrip arm of the bridge.

19. The Doppler microwave detection module according to claim 18, wherein the ground pad is arranged to be isolated from the two ground pads by the first microstrip arm at the inward concavity corresponding to the boundary of the first microstrip arm of the bridge, and the ground pad is wholly or partially located in the inward concavity space corresponding to the boundary of the first microstrip arm of the bridge.

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