Cavity duplexer and radar calibration system

Abstract

The utility model discloses a cavity duplexer and radar calibration system, the cavity duplexer includes apron, main part, connector, tuning screw rod and coupling screw rod, the inside of main part is divided into first cavity and second cavity by partition, is equipped with a plurality of first sub -cavity and second sub -cavity in first cavity and second cavity respectively, and between two first sub -cavity and between two second sub -cavity of adjacent respectively open first coupling window and second coupling window, and is equipped with a first resonant cavity and a second resonant cavity in every first sub -cavity and every second sub -cavity respectively, every first resonant cavity and every second resonant cavity all correspond to a tuning screw rod, and every adjacent two first resonant cavities and every adjacent two second resonant cavities all correspond to a coupling screw rod. In the multi -frequency cooperation radar calibration system, utilize the cavity duplexer of the utility model can realize seamless switching of different frequency band, and the automation degree of multi -frequency calibration has been improved.

Description

Technical Field

[0001] This utility model belongs to the field of radar calibration technology, and in particular relates to a cavity duplexer and a radar calibration system. Background Technology

[0002] Phased array radar calibration systems primarily ensure beam pointing accuracy and signal consistency by calibrating the amplitude and phase errors of the antenna array. The calibration process includes internal and external calibration. Internal calibration utilizes an internal calibration network or near-field radiation characteristics to monitor channel amplitude and phase errors in real time without external equipment. External calibration involves transmitting a known signal from an external beacon source; the radar receives this signal and compares the theoretical and actual measured values ​​to calculate and compensate for the amplitude and phase errors. Reduced antenna spacing (especially in the X-band and above) enhances near-field coupling, making traditional internal calibration inaccurate in describing complex electromagnetic interactions. Traditional external calibration requires transporting instruments to high locations (such as towers), is complex, cannot cover the entire link, and for multi-band radars, often requires multiple calibration sources, resulting in long processing times and low efficiency.

[0003] The phased array radar calibration system uses a combination of multiple cavity filters and single-pole multi-throw switches, which results in a complex system structure, high cost, large size, and reliance on switches to switch signal paths, requiring additional control circuitry. Utility Model Content

[0004] The purpose of this invention is to provide a cavity duplexer and radar calibration system to solve the problems of complex structure, high cost, large size and complex control of traditional calibration systems.

[0005] This utility model solves the above-mentioned technical problems through the following technical solution: a cavity duplexer, including a cover plate, a main body, a connector, a tuning screw, and a coupling screw; the cover plate is disposed on the main body and seals the main body; the interior of the main body is divided into a first cavity and a second cavity by a partition wall, and the first cavity and the second cavity are connected on one side; a plurality of first sub-cavities are provided in the first cavity, and a first coupling window is opened between two adjacent first sub-cavities, and a first resonant cavity is provided in each first sub-cavity; a plurality of second sub-cavities are provided in the second cavity, and a second coupling window is opened between two adjacent second sub-cavities, and a second resonant cavity is provided in each second sub-cavity;

[0006] Each first resonant cavity and each second resonant cavity corresponds to a tuning screw. One end of the tuning screw is located on the cover plate, and the other end passes through the cover plate and is inserted into the corresponding first resonant cavity or second resonant cavity. Each pair of adjacent first resonant cavities and each pair of adjacent second resonant cavities corresponds to a coupling screw. One end of the coupling screw is located on the cover plate, and the other end passes through the cover plate and is located above the midpoint of the two adjacent first resonant cavities or second resonant cavities.

[0007] The connector is disposed on the main body and includes a first connector, a second connector and a third connector. The probe of the first connector is connected to the first first resonant cavity and the first second resonant cavity through a connecting rod. The probe of the second connector is connected to the last first resonant cavity. The probe of the third connector is connected to the last second resonant cavity.

[0008] Furthermore, both the first coupling window and the second coupling window are air windows.

[0009] Furthermore, the cover plate is locked to the body by a plurality of first screws.

[0010] Furthermore, mounting holes are provided on the cover plate and the main body.

[0011] Furthermore, the plurality of first sub-cavities and the plurality of second sub-cavities are arranged in an M-shape.

[0012] Furthermore, the main body is rectangular.

[0013] Furthermore, both the first cavity and the second cavity are metal cavities, and their inner walls are silver-plated.

[0014] Based on the same concept, this utility model also provides a radar calibration system, including a control terminal, a detection module, a first antenna, a second antenna, and a dual-band signal generation unit, a first duplexer, a broadband amplifier circuit, a transceiver switch, and a second duplexer connected in sequence. The detection module is connected to the transceiver switch and the control terminal, and the second duplexer is connected to the first antenna and the second antenna. Both the first duplexer and the second duplexer adopt the cavity duplexer described above.

[0015] During transmission mode calibration, a C-band RF signal and an X-band RF signal are generated by a dual-band signal generation unit. The C-band RF signal and the X-band RF signal are combined into a broadband RF signal by a first duplexer. The broadband RF signal is amplified by a broadband amplifier circuit and then enters a second duplexer through a transceiver switch. The second duplexer splits the signal into two paths, which are then radiated outwards by the first antenna and the second antenna, respectively.

[0016] During receiver mode calibration, the radar echo signal is received by the first antenna and the second antenna, and then combined into a broadband echo signal by the second duplexer. The broadband echo signal enters the detector module through the transceiver switch. The detector module detects the amplitude of the broadband echo signal and converts it into a digital signal. The digital signal is then processed to obtain the signal power, and finally the signal power is sent to the control terminal.

[0017] Furthermore, the second duplexer is connected to the first antenna and the second antenna via cables. The dual-band signal generation unit, the first duplexer, the broadband amplifier circuit, the transceiver switch, and the second duplexer are connected sequentially via printed circuit board microstrip lines. The detector module is connected to the transceiver switch via printed circuit board microstrip lines.

[0018] Furthermore, the dual-band signal generation unit includes a signal generator, an FPGA, a DDS, a clock circuit, a phase-locked loop (PLL), a C-band amplification and filtering circuit, an X-band amplification and filtering circuit, an intermediate frequency (IF) amplification and filtering circuit, a power divider, a first mixer, and a second mixer. The signal generator is connected to the clock circuit, the PLL, the DDS, and the FPGA. The PLL is connected to the C-band and X-band amplification and filtering circuits. The C-band amplification and filtering circuit is connected to the first mixer, and the X-band amplification and filtering circuit is connected to the second mixer. The DDS, the IF amplification and filtering circuit, and the power divider are connected in sequence. The power divider is also connected to the first mixer and the second mixer.

[0019] The signal generator produces a specific frequency signal based on the clock signal provided by the clock circuit. The phase-locked loop (PLL) produces a C-band local oscillator (LOO) signal and an X-band LOO signal based on the specific frequency signal. The C-band LOO signal is amplified and filtered by a C-band amplification and filtering circuit before entering the first mixer, and the X-band LOO signal is amplified and filtered by an X-band amplification and filtering circuit before entering the second mixer. The DDS generates an intermediate frequency (IF) signal based on the specific frequency signal. The IF signal is amplified and filtered by an IF amplification and filtering circuit before entering the power divider. The amplified and filtered IF signal is split into two paths by the power divider: one path is mixed with the amplified and filtered C-band LOO signal in the first mixer to obtain the C-band RF signal; the other path is mixed with the amplified and filtered X-band LOO signal in the second mixer to obtain the X-band RF signal.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0021] This invention provides a cavity duplexer based on frequency division duplex mode. It utilizes the bandpass filtering characteristics of the first and second resonant cavities to separate signals into signals of different frequencies, or to combine signals of different frequencies into a broadband signal, thereby achieving multi-frequency coordination during radar calibration. Compared to traditional calibration systems that often use a combination of multiple cavity filters and two single-pole double-throw switches, this invention uses a cavity duplexer to replace them, reducing the cost and size of the radar calibration system. It also eliminates the need for manual replacement of antennas and filters to switch frequency bands, improving the automation level of multi-frequency calibration. Furthermore, it eliminates the need for additional control circuitry, reducing losses and control complexity.

[0022] The cavity duplexer of this invention has the advantages of compact structure, low loss, high out-of-band suppression and high isolation. Attached Figure Description

[0023] To more clearly illustrate the technical solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is an external view of the cavity duplexer in an embodiment of this utility model;

[0025] Figure 2 This is a schematic diagram of the internal structure of the cavity duplexer in this embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the coupling of each cavity in an embodiment of this utility model;

[0027] Figure 4 This is the C-band filtering curve of the cavity duplexer in this embodiment of the present invention;

[0028] Figure 5 This is the X-band filtering curve of the cavity duplexer in this embodiment of the present invention;

[0029] Figure 6 This is the full-frequency amplitude curve of the cavity duplexer in this embodiment of the present invention;

[0030] Figure 7 This is a schematic diagram of the radar calibration system in an embodiment of this utility model.

[0031] Explanation of reference numerals in the attached drawings: 1-cover plate, 2-main body, 20-common cavity, 21-partition wall, 22-first resonant cavity, 23-second resonant cavity, 24-first cavity, 25-second cavity, 26-air window, 3-coupling screw, 4-tuning screw, 5-first screw, 6-fixing screw, 7-probe of the first connector, 71-connecting rod, 8-probe of the second connector, 9-probe of the third connector. Detailed Implementation

[0032] The technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0033] The technical solution of this utility model will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0034] Example 1

[0035] like Figure 1 and Figure 2 As shown, the cavity duplexer provided by this utility model includes a cover plate 1, a main body 2, a connector, a tuning screw 4, and a coupling screw 3; the cover plate 1 is disposed on the main body 2 and seals the main body 2; the interior of the main body 2 is divided into a first cavity 24 and a second cavity 25 by a partition wall 21. The first cavity 24 is provided with a plurality of first sub-cavities, and a first coupling window is provided between two adjacent first sub-cavities. A first resonant cavity 22 is provided in each first sub-cavity; the second cavity 25 is provided with a plurality of second sub-cavities, and a second coupling window is provided between two adjacent second sub-cavities. A second resonant cavity 23 is provided in each second sub-cavity.

[0036] Each first resonant cavity 22 and each second resonant cavity 23 corresponds to a tuning screw 4. One end of the tuning screw 4 is located on the cover plate 1, and the other end passes through the cover plate 1 and is inserted into the corresponding first resonant cavity 22 or second resonant cavity 23. Each pair of adjacent first resonant cavities 22 and each pair of adjacent second resonant cavities 23 corresponds to a coupling screw 3. One end of the coupling screw 3 is located on the cover plate 1, and the other end passes through the cover plate 1 and is located above the midpoint of the two adjacent first resonant cavities 22 or second resonant cavities 23.

[0037] The connector is sintered on the main body 2 and includes a first connector, a second connector and a third connector. The probe 7 of the first connector is connected to the first first resonant cavity 22 and the first second resonant cavity 23 through the connecting rod 71. The probe 8 of the second connector is connected to the last first resonant cavity 22. The probe 9 of the third connector is connected to the last second resonant cavity 23.

[0038] Each of the cover plate 1 and the main body 2 has one mounting hole on its four sides. A fixing screw 6 passes through these mounting holes, penetrating the entire cover plate 1 and main body 2, to secure the duplexer. The cover plate 1 and main body 2 are locked together by multiple first screws 5, forming a closed cavity. Figure 1As shown, the number of first screws 5 is 17. Each tuning screw 4 is fixed to the cover plate 1 by a nut. Adjusting the depth of the tuning screw 4 into the corresponding first resonant cavity 22 or second resonant cavity 23 can change the resonant frequency of the corresponding first resonant cavity 22 or second resonant cavity 23; the greater the depth, the lower the resonant frequency. Each coupling screw 3 is located above the midpoint of two adjacent first resonant cavities 22 or second resonant cavities 23. The coupling screw 3 is also fixed to the cover plate 1 by a nut. Adjusting the depth of the coupling screw 3 into the main body 2 can change the coupling coefficient between two adjacent first resonant cavities 22 or second resonant cavities 23; the greater the depth, the greater the coupling coefficient.

[0039] like Figure 2 As shown, the interior of the main body 2 is divided into a first cavity 24 and a second cavity 25 by a partition wall 21. The first cavity 24 and one side of the second cavity 25 are connected, and this connected portion can be considered a common cavity 20. That is, the common cavity 20 is located on one side of the first cavity 24 and the second cavity 25. The probe 7 of the first connector is located in the common cavity 20 and is connected to the first first resonant cavity 22 and the first second resonant cavity 23 via a connecting rod 71. The distance from the connection point of the connecting rod 71 to the first first resonant cavity 22 and the first second resonant cavity 23 to the bottom of the corresponding cavity (i.e., the first sub-cavity and the second sub-cavity) determines the tap delay of the two filters. The specific formula is as follows:

[0040] t d =2*(Q) ext / π)*F c (1)

[0041] Among them, t d Q represents the tap delay. ext F represents the external Q value. c This indicates the center frequency of the signal. Generally, the higher the connection point, the smaller the tap delay. The connecting rod needs to be welded to the corresponding resonant cavity to ensure the time delay stability of the cavity duplexer.

[0042] In a specific embodiment of this utility model, both the first coupling window and the second coupling window are air windows 26.

[0043] In a specific embodiment of this utility model, both the first cavity 24 and the second cavity 25 are metal cavities (e.g., copper, aluminum, or stainless steel), and their inner walls are silver-plated, which improves the conductivity of the metal and reduces the insertion loss of the cavity duplexer.

[0044] In a specific embodiment of this utility model, the main body 2 is rectangular or circular, and the multiple first sub-cavities and multiple second sub-cavities are arranged in an M-shape (or in a straight line or U-shape, etc.). Adjacent first sub-cavities or second sub-cavities are coupled by an air window 26, which makes the cavity duplexer have the advantages of compact structure, low loss, high out-of-band suppression and high isolation.

[0045] Figure 3 This illustrates the coupling relationship between the first and second sub-cavities in an M-shaped arrangement. Figure 3 It can be seen that the signal link is divided into two segments: R0-->R1-->R2-->R3-->R4-->R5-->R6-->R7.

[0046] The signal path is connected via R0-->R8-->R9-->R10-->R11-->R12-->R13-->R14, with air windows 26 for coupling. Each of the seven first sub-cavities (or second sub-cavities) has a cylindrical first resonant cavity 22 (or second resonant cavity 23). The resonant frequency of the first resonant cavity 22 (or second resonant cavity 23) is adjusted by changing the depth of the tuning screw 4 corresponding to that cavity; a greater depth results in a lower resonant frequency. A coupling screw 3 corresponds to the center position between any two adjacent first resonant cavities 22 and any two adjacent second resonant cavities 23. The coupling coefficient between adjacent resonant cavities is adjusted by changing the depth of the coupling screw 3 within the first or second sub-cavity; a greater depth results in a greater coupling coefficient.

[0047] The first two resonant cavities 22 and the second two resonant cavities 23 at both ends are connected to connector probes. The probes can be glass insulators, SMP, or SMA to achieve signal connection. In addition to the signal transmission direction, the probe protrusion direction can be any direction, such as front, back, left, or right, and can be flexibly adjusted according to the actual application scenario.

[0048] A cavity duplexer is a three-port device. Taking the common terminal (i.e., the first connector) of the cavity duplexer as port 1 and the C-band signal output as port 2 (i.e., the second connector) as an example, S11 represents the magnitude of the electromagnetic wave reflected from port 1, S22 represents the magnitude of the electromagnetic wave reflected from port 2, and S21 represents the magnitude of the electromagnetic wave from port 1 to port 2. Figure 4 It can be seen that in the 5.3–5.7 GHz range, both S11 and S22 are below -15 dB, indicating very low reflection; S21 is below -0.5 dB, indicating very low loss; while in the 5–5.2 GHz and 5.8–6 GHz ranges, S21 is below -40 dB, indicating that most electromagnetic waves do not pass through and are suppressed inside the cavity duplexer. Combined, it can be seen that ports 1 and 2 of this cavity duplexer only allow electromagnetic waves in the 5.3–5.7 GHz range to pass through, achieving frequency selection; and the in-band loss in the 5.3–5.7 GHz range is less than 1 dB, the out-of-band suppression reaches about 40 dB at 5100 MHz and 5900 MHz, and the transition band is 200 MHz, demonstrating excellent filtering performance.

[0049] Taking the common terminal of the cavity duplexer as port 1 and the X-band signal output as port 3 (i.e., the third connector) as an example, S11 represents the magnitude of the electromagnetic wave reflected from port 1, S33 represents the magnitude of the electromagnetic wave reflected from port 2, and S31 represents the magnitude of the electromagnetic wave from port 1 to port 3. Figure 5 It can be seen that in the 9.3–9.5 GHz range, both S11 and S33 are below -20 dB, indicating very low reflection; S31 is below -1 dB, indicating very low loss; while in the 9–9.2 GHz and 9.6–10 GHz ranges, S31 is below -30 dB, indicating that most electromagnetic waves do not pass through and are suppressed inside the cavity duplexer. Combined, it can be seen that ports 1 to 3 of this cavity duplexer only allow electromagnetic waves in the 9.3–9.5 GHz range to pass through, achieving frequency selection; and the in-band loss in the 9.3–9.5 GHz range is less than 1 dB, the out-of-band suppression reaches approximately 33 dB at 9200 MHz and 9600 MHz, and the transition band is 100 MHz, demonstrating excellent filtering performance.

[0050] from Figure 6 It can be seen that the cavity duplexer has a good suppression effect in the C-band (5.3-5.7GHz) and X-band (9.3-9.5GHz) frequency bands, and the isolation between the two frequency bands is very high (above 100dB) with no mutual interference. The cavity duplexer achieves frequency selection functions with compact structure, low loss, high out-of-band suppression and high isolation.

[0051] Example 2

[0052] like Figure 7 As shown, the radar calibration system provided by this utility model includes a control terminal, a detection module, a first antenna (i.e., a C-band antenna), a second antenna (i.e., an X-band antenna), and a dual-band signal generation unit, a first duplexer, a broadband amplifier circuit, a transceiver switch, and a second duplexer connected in sequence. The detection module is connected to the transceiver switch and the control terminal, and the second duplexer is connected to the first antenna and the second antenna. Both the first duplexer and the second duplexer adopt the cavity duplexer as described in Embodiment 1 of this utility model.

[0053] During transmission mode calibration, a dual-band signal generation unit generates C-band and X-band radio frequency signals. The C-band and X-band radio frequency signals are combined into a broadband radio frequency signal by a first duplexer. The broadband radio frequency signal is amplified by a broadband amplifier circuit and then enters a second duplexer through a transceiver switch. The second duplexer splits the signal into two paths, which are then radiated outwards through the first and second antennas, respectively, to detect the C-band and X-band radar radiation power.

[0054] During receiver mode calibration, the radar echo signal is received by the first and second antennas and combined into a broadband echo signal by the second duplexer. The broadband echo signal enters the detector module through the transceiver switch. The detector module detects the amplitude of the broadband echo signal and converts it into a digital signal. The digital signal is then processed to obtain the signal power. Finally, the signal power is sent to the control terminal through the communication module to realize the detection of C-band and X-band radar receive power.

[0055] In a specific embodiment of this utility model, the dual-band signal generation unit includes a signal generator, an FPGA, a DDS, a clock circuit, a phase-locked loop (PLL), a C-band amplification and filtering circuit, an X-band amplification and filtering circuit, an intermediate frequency (IF) amplification and filtering circuit, a power divider, a first mixer, and a second mixer. The signal generator is connected to the clock circuit, the PLL, the DDS, and the FPGA. The PLL is connected to the C-band and X-band amplification and filtering circuits. The C-band amplification and filtering circuit is connected to the first mixer, and the X-band amplification and filtering circuit is connected to the second mixer. The DDS, the IF amplification and filtering circuit, and the power divider are connected in sequence. The power divider is also connected to the first and second mixers. The first and second mixers are respectively connected to a first duplexer.

[0056] The signal generator produces a specific frequency signal based on the clock signal provided by the clock circuit. The phase-locked loop (PLL) produces a C-band local oscillator (LOO) signal and an X-band LOO signal based on the specific frequency signal. The C-band LOO signal is amplified and filtered by a C-band amplification and filtering circuit before entering the first mixer, and the X-band LOO signal is amplified and filtered by an X-band amplification and filtering circuit before entering the second mixer. The DDS generates an intermediate frequency (IF) signal based on the specific frequency signal. The IF signal is amplified and filtered by an IF amplification and filtering circuit before entering the power divider. The amplified and filtered IF signal is split into two paths by the power divider: one path is mixed with the amplified and filtered C-band LOO signal in the first mixer to obtain the C-band RF signal; the other path is mixed with the amplified and filtered X-band LOO signal in the second mixer to obtain the X-band RF signal.

[0057] In a specific embodiment of this invention, the second duplexer is connected to the first and second antennas via cables. The dual-band signal generation unit, the first duplexer, the broadband amplifier circuit, the transceiver switch, and the second duplexer are sequentially connected via printed circuit board microstrip lines. The detection module is connected to the transceiver switch via printed circuit board microstrip lines. All connections within the dual-band signal generation unit are implemented via printed circuit board microstrip lines. This connection method makes the radar calibration system layout compact and reduces the system size.

[0058] The first duplexer combines C-band and X-band radio frequency signals into a broadband radio frequency signal, enabling multi-frequency coordinated radar calibration without the need for manual antenna and filter replacement for frequency band switching. In other words, this invention achieves seamless switching between different frequency bands during multi-frequency coordinated radar calibration using a low-loss, high-suppression cavity duplexer, improving the automation level of multi-frequency calibration.

[0059] The radar calibration system of this invention can be fixedly installed on the ground or mounted on a drone, realizing automated calibration and real-time compensation for C-band and X-band radars.

[0060] The above description only discloses specific embodiments of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A cavity duplexer, characterized in that, The cavity duplexer includes a cover plate, a main body, a connector, a tuning screw, and a coupling screw; the cover plate is disposed on the main body and seals the main body; the interior of the main body is divided into a first cavity and a second cavity by a partition wall, and the first cavity and the second cavity are connected on one side; a plurality of first sub-cavities are provided in the first cavity, and a first coupling window is opened between two adjacent first sub-cavities, and a first resonant cavity is provided in each first sub-cavity; a plurality of second sub-cavities are provided in the second cavity, and a second coupling window is opened between two adjacent second sub-cavities, and a second resonant cavity is provided in each second sub-cavity; Each first resonant cavity and each second resonant cavity corresponds to a tuning screw. One end of the tuning screw is located on the cover plate, and the other end passes through the cover plate and is inserted into the corresponding first resonant cavity or second resonant cavity. Each pair of adjacent first resonant cavities and each pair of adjacent second resonant cavities corresponds to a coupling screw. One end of the coupling screw is located on the cover plate, and the other end passes through the cover plate and is located above the midpoint of the two adjacent first resonant cavities or second resonant cavities. The connector is disposed on the main body and includes a first connector, a second connector and a third connector. The probe of the first connector is connected to the first first resonant cavity and the first second resonant cavity through a connecting rod. The probe of the second connector is connected to the last first resonant cavity. The probe of the third connector is connected to the last second resonant cavity.

2. The cavity duplexer according to claim 1, characterized in that, Both the first coupling window and the second coupling window are air windows.

3. The cavity duplexer according to claim 1, characterized in that, The cover plate is locked to the main body by a plurality of first screws.

4. The cavity duplexer according to claim 1, characterized in that, Mounting holes are provided on the cover plate and the main body.

5. The cavity duplexer according to claim 1, characterized in that, The multiple first sub-cavities and the multiple second sub-cavities are arranged in an M-shape.

6. The cavity duplexer according to claim 1, characterized in that, The main body is rectangular.

7. The cavity duplexer according to any one of claims 1 to 6, characterized in that, Both the first cavity and the second cavity are metal cavities, and their inner walls are silver-plated.

8. A radar calibration system, characterized in that, The calibration system includes a control terminal, a detection module, a first antenna, a second antenna, and a dual-band signal generation unit, a first duplexer, a broadband amplifier circuit, a transceiver switch, and a second duplexer connected in sequence. The detection module is connected to the transceiver switch and the control terminal, and the second duplexer is connected to the first antenna and the second antenna. Both the first duplexer and the second duplexer are cavity duplexers as described in any one of claims 1 to 7.

9. The radar calibration system according to claim 8, characterized in that, The second duplexer is connected to the first and second antennas via cables. The dual-band signal generation unit, the first duplexer, the broadband amplifier circuit, the transceiver switch, and the second duplexer are connected in sequence via printed circuit board microstrip lines. The detector module is connected to the transceiver switch via printed circuit board microstrip lines.

10. The radar calibration system according to claim 8, characterized in that, The dual-band signal generation unit includes a signal generator, an FPGA, a DDS, a clock circuit, a phase-locked loop (PLL), a C-band amplification and filtering circuit, an X-band amplification and filtering circuit, an intermediate frequency (IF) amplification and filtering circuit, a power divider, a first mixer, and a second mixer. The signal generator is connected to the clock circuit, the PLL, the DDS, and the FPGA. The PLL is connected to the C-band and X-band amplification and filtering circuits. The C-band amplification and filtering circuit is connected to the first mixer, and the X-band amplification and filtering circuit is connected to the second mixer. The DDS, the IF amplification and filtering circuit, and the power divider are connected in sequence. The power divider is also connected to the first mixer and the second mixer.

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