Non-standard short wave balun unbalance degree testing device and testing method

Abstract

This invention discloses a non-standard shortwave balun unbalance testing device and method, comprising a non-standard balanced port testing fixture and a non-standard unbalanced port testing fixture, which are respectively connected to two ports of a vector network analyzer. The non-standard unbalanced port testing fixture includes a first coaxial cable connection structure, one end of which is an unbalanced test terminal and the other end is an RF terminal one, which is connected to one port of the vector network analyzer. The non-standard balanced port testing fixture includes a metallic virtual ground, a load body, and a second coaxial cable connection structure, one end of which is a balanced test terminal and the other end is an RF terminal two, which is connected to another port of the vector network analyzer. This invention addresses the problem of testing large-size non-standard shortwave baluns with multiple equivalent ports using simple fixtures and a vector network analyzer with fewer ports.

Description

Technical Field

[0001] This invention relates to the field of passive testing technology, specifically to a large-size port non-standard short-wave balun unbalance testing device and method. Background Technology

[0002] Traditional balun testing methods require that both the balanced and unbalanced ends of the balun have standard RF interfaces, such as SMA or N-type interfaces, and that the vector network analyzer has a port count greater than or equal to the equivalent port count of the balun. However, converting the balanced and unbalanced ends of a shortwave balun to a standard RF interface requires a conversion fixture, especially in the low-frequency band where the length of the conversion fixture is comparable to the wavelength, often reaching several meters. Furthermore, the equivalent port count of a balun is typically three, which places high demands on the number of ports on the vector network analyzer. Therefore, traditional balun testing methods have high requirements for the number of ports on the vector network analyzer and the quality of the fixture, resulting in high testing complexity and high hardware costs.

[0003] With the development of wireless communication, the requirements for passive testing of systems are constantly increasing. There is an urgent need to use simple tooling and vector network analyzers with fewer ports to test large-port non-standard shortwave baluns. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to reduce the limitation of the number of ports of a vector network analyzer on balun imbalance testing and reduce the complexity of the test.

[0005] The present invention solves the above-mentioned technical problems through the following technical means:

[0006] A non-standard short-wave balun unbalance test device is proposed. The device includes: a non-standard balanced port test fixture and a non-standard unbalanced port test fixture, which are respectively connected to the two ports of a vector network analyzer. The non-standard unbalanced port test fixture includes a first coaxial cable connection structure. One end of the first coaxial cable connection structure is the unbalanced test end, and the other end is the first radio frequency end. The first radio frequency end is connected to one port of the vector network analyzer. The non-standard balanced port test fixture includes a metal virtual ground, a load body, and a second coaxial cable connection structure. One end of the second coaxial cable connection structure is the balanced test end, and the other end is the second RF end, which is connected to another port of the vector network analyzer.

[0007] Furthermore, the first coaxial cable connection structure includes a first coaxial cable, one end of which is equipped with a conversion interface to form a radio frequency terminal, and the other end is an unbalanced test terminal. The unbalanced test terminal includes a wire led out from the inner conductor of the first coaxial cable and several wires led out from the outer conductor.

[0008] Furthermore, the second coaxial cable connection structure includes a second coaxial cable, one end of which is equipped with a conversion interface to form a radio frequency end, and the other end is a balanced test end. The balanced test end includes a wire led out from the inner conductor of the second coaxial cable and a wire led out from the outer conductor.

[0009] Furthermore, several wires extending from the outer conductor of the first coaxial cable are arranged around a single wire extending from the inner conductor of the first coaxial cable to enclose the single wire in the middle.

[0010] Furthermore, the conversion interface adopts an SMA interface or an N-type interface.

[0011] Furthermore, a metal connector is provided at the end of the wire.

[0012] Furthermore, the metal connector is a metal clip.

[0013] Furthermore, wires are connected to both ends of the load body.

[0014] Furthermore, the load value of the load body is the non-standard balanced port impedance value minus the vector network analyzer port impedance value.

[0015] Furthermore, this invention also proposes a method for testing the unbalance of a non-standard short-wavelength balun, which uses the non-standard short-wavelength balun unbalance testing device described above to test the short-wavelength balun, wherein the short-wavelength balun includes a non-standard unbalanced end and a non-standard balanced end, and the testing method includes: Connect the unbalanced test terminal of the non-standard unbalanced port test fixture to interface A and grounding port D on the non-standard unbalanced terminal; and connect the grounding port D of the non-standard balanced terminal to the metal virtual ground. Connect the balance test terminal of the non-standard balanced port test fixture to interface C and grounding port D on the non-standard balanced terminal, and connect both ends of the load body to interfaces B and D on the non-standard balanced terminal. Then, read the S value using a vector network analyzer. 21 The first phase value; Replace one end of the load body connected to interface B on the non-standard balancing terminal with interface C on the non-standard balancing terminal, and replace one end of the balancing test terminal connected to interface C on the non-standard balancing terminal with interface B on the non-standard balancing terminal. Then read the S value using a vector network analyzer. 21 The second phase value; The amplitude-phase imbalance of the short-wave balun is calculated based on the first and second phase values.

[0016] Furthermore, the first phase value includes S 21 The amplitude value A1 and the phase value P1, wherein the second amplitude and phase values ​​include S21 The amplitude value A2 and the phase value P2; The calculation of the amplitude-phase imbalance of the short-wave balun based on the first and second amplitude-phase values ​​includes: Calculate A1-A2 as the amplitude imbalance of the shortwave balun; Calculate P1-P2-180° as the phase imbalance of the shortwave balun.

[0017] Furthermore, a wire leading from the inner conductor of the second coaxial cable in the unbalanced test terminal is connected to interface A on the non-standard unbalanced terminal, and several wires leading from the outer conductor of the second coaxial cable in the unbalanced test terminal are evenly connected to the grounding port D on the non-standard balanced terminal.

[0018] Furthermore, a wire leading from the inner conductor of the second coaxial cable is connected to interface C or interface B on the non-standard balance terminal, and a wire leading from the outer conductor of the second coaxial cable is connected to the grounding port D on the non-standard balance terminal.

[0019] Furthermore, the metal virtual ground is installed at the midpoint between interface B and interface C of the non-standard balance end, so that interface B and interface C of the non-standard balance end are symmetrically distributed with respect to the metal virtual ground.

[0020] The advantages of this invention are: (1) The test device proposed in this invention has a simple structure. It can test large-size port non-standard short-wave baluns by using non-standard balanced port test fixtures, non-standard unbalanced port test fixtures and vector network analyzers with fewer ports. It realizes the testing of non-standard ports equivalent to 3-port baluns using 2-port vector network analyzers, effectively reducing the complexity of testing and reducing costs, and has great engineering application value.

[0021] (2) In the non-standard unbalanced port test fixture, the multiple wires leading out from the outer conductor of the first coaxial cable wrap around the single wire leading out from the inner conductor of the first coaxial cable. This setting can maintain the electromagnetic wave mode in the radio frequency coaxial cable as much as possible.

[0022] (3) During the test, the metal virtual ground is installed at the middle position of interface B and interface C on the non-standard balance end, so that interface B and interface C are symmetrical with respect to the metal virtual ground, so as to reduce the influence of the metal virtual ground on the balance port field and thus reduce the inaccuracy of the unbalance measurement.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0025] Figure 1 This is a schematic diagram of the structure of a non-standard short-wave balun unbalance testing device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the installation and connection of the balanced and unbalanced ports of the balun in one embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the balun to be tested in one embodiment of the present invention; Figure 4 This is a flowchart illustrating a non-standard shortwave balun unbalance test method proposed in an embodiment of the present invention. Figure 5 This is a schematic diagram of the unbalance test results of the balun under test in one embodiment of the present invention; Figure 6 This is a schematic diagram of the simulation results of the unbalance of the balun under test in one embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figures 1 to 2 As shown, the first embodiment of the present invention proposes a non-standard short-wave balun unbalance test device. The test device includes: a non-standard balanced port test fixture and a non-standard unbalanced port test fixture, which are respectively connected to two ports of a vector network analyzer. The non-standard unbalanced port test fixture includes a first coaxial cable connection structure. One end of the first coaxial cable connection structure is the unbalanced test end, and the other end is the first radio frequency end. The first radio frequency end is connected to one port of the vector network analyzer. The non-standard balanced port test fixture includes a metal virtual ground, a load body, and a second coaxial cable connection structure. One end of the second coaxial cable connection structure is the balanced test end, and the other end is the second RF end, which is connected to another port of the vector network analyzer.

[0028] Specifically, such as Figure 3As shown, the shortwave balun under test includes a non-standard unbalanced end and a non-standard balanced end. During actual testing, the shortwave balun under test, a vector network analyzer, and testing fixtures are assembled and connected: the unbalanced test terminal of the non-standard unbalanced port testing fixture is connected to interface A and grounding port D on the non-standard unbalanced end of the balun; the metal virtual ground in the non-standard balanced port testing fixture is connected to grounding port D on the non-standard balanced end; then, the balanced test terminal of the non-standard balanced port testing fixture is connected to interface C and grounding port D on the non-standard balanced end, and both ends of the load body are connected to interface B and interface D on the non-standard balanced end. The S signal is then read using the vector network analyzer. 21 The first phase value; then, replace one end of the load body connected to interface B on the non-standard balancing terminal with interface C on the non-standard balancing terminal, and replace one end of the balance test terminal connected to interface C on the non-standard balancing terminal with interface B on the non-standard balancing terminal, and read S using a vector network analyzer. 21 The second phase value is obtained; finally, based on the first and second phase values, the amplitude and phase imbalance of the shortwave balun is calculated.

[0029] It should be noted that the virtual metal ground mentioned in this embodiment refers to a virtual ground of microwaves.

[0030] As a further preferred technical solution, the first coaxial cable connection structure includes a first coaxial cable, one end of which is equipped with a conversion interface to form a radio frequency terminal, and the other end is an unbalanced test terminal. The unbalanced test terminal includes a wire led out from the inner conductor of the first coaxial cable and several wires led out from the outer conductor.

[0031] It should be noted that the RF terminal is connected to port 1 of the vector network analyzer, and a wire leading out from the inner conductor of the first coaxial cable serves as a port connected to port A on the unbalanced end of the balun under test. Several wires leading out from the outer conductor of the first coaxial cable serve as ports connected to the grounding port D on the unbalanced end of the balun under test.

[0032] Preferably, during actual testing, several wires leading from the outer conductor of the first coaxial cable are evenly connected to the grounding port D on the non-standard unbalanced end. This simulates the coaxial structure, forming a near-coaxial structure and reducing measurement errors.

[0033] As a further preferred technical solution, several wires extending from the outer conductor of the first coaxial cable are arranged around a single wire extending from the inner conductor of the first coaxial cable to enclose the single wire in the middle. By enclosing the wire extending from the inner conductor with multiple wires extending from the outer conductor, the electromagnetic wave pattern in the first coaxial cable can be preserved as much as possible.

[0034] As a further preferred technical solution, the second coaxial cable connection structure includes a second coaxial cable, one end of which is equipped with a conversion interface to form a radio frequency end, and the other end is a balanced test end. The balanced test end includes a wire led out from the inner conductor of the second coaxial cable and a wire led out from the outer conductor.

[0035] It should be noted that one wire leading out from the inner conductor of the second coaxial cable is used as a port to connect to port B or port C on the unbalanced end of the balun under test, and one wire leading out from the outer conductor of the second coaxial cable is used as a port to connect to the grounding port D on the unbalanced end of the balun under test.

[0036] As a further preferred technical solution, the conversion interface installed on the first coaxial cable and the second coaxial cable adopts an SMA interface or an N-type interface.

[0037] In this embodiment, an SMA or N-type interface is added to one end of the coaxial cable to convert one end of the coaxial cable into a standard radio frequency interface, which is adapted to the port of the vector network analyzer.

[0038] As a further preferred technical solution, metal connectors are provided at the ends of the wires leading out from the inner and outer conductors of the first and second coaxial cables to better connect them to the port of the balun under test.

[0039] As a further preferred technical solution, the metal connector is a metal clip. By setting the metal connector as a metal clip, it can be easily clipped onto the balun port during testing.

[0040] As a further preferred technical solution, the two ends of the load body are respectively connected with wires. During the test, one end of the load is electrically connected to port B or port C on the non-standard balance end of the balun under test via a wire, and the other end is electrically connected to port D on the non-standard balance end via a wire.

[0041] The load value of the load body should be the non-standard balanced port impedance value of the balun under test minus the port impedance value of the vector network analyzer used.

[0042] Specifically, the non-standard short-wavelength balun imbalance testing device proposed in this embodiment is used to test the balun under test as follows: Connect the metal clip leading from the inner conductor of the first coaxial cable in the non-standard unbalanced port test fixture to port A of the balun non-standard unbalanced port, and evenly connect the metal clip leading from the outer conductor of the first coaxial cable to port D of the balun non-standard unbalanced port; connect the RF end of the first coaxial cable in the non-standard unbalanced port test fixture to port 1 of the vector network analyzer.

[0043] Connect one end of the load in the non-standard balanced port test fixture to port B of the non-standard balanced balun, and the other end of the load to port D of the non-standard balanced balun. The principle for fixing the load and the connecting wires is to minimize the impact on the electromagnetic field of the balanced port, and to ensure that the impact on ports B and C of the non-standard balanced port is similar. The metal clip of the inner conductor of the second coaxial cable is clamped to port C of the non-standard balanced port, and the metal clip of the outer conductor is clamped to port D of the non-standard balanced port. The connecting wires are then fixed, again with the principle of minimizing the impact on the electromagnetic field of the non-standard balanced port, or ensuring that the impact on ports B and C is similar. Then, connect the RF end of the second coaxial cable to port 2 of the vector network analyzer and read the S... 21 The amplitude value A1 (dB) and phase value P1 (°).

[0044] The load connection at one end of port B is changed to port C. The principle for fixing the load body and the connecting wire is to minimize the impact on the electromagnetic field of the balanced port, and to ensure that the impact on ports B and C is similar (e.g., fixed within the range of a metal virtual ground). The metal clip of the wire leading out from the inner conductor of the second coaxial cable is replaced with one connected to port B, and the connection structure is fixed. The principle for fixing is to minimize the impact on the electromagnetic field of the balanced port, or to ensure that the impact on ports B and C is similar; then read S. 21 The amplitude value A2 (dB) and phase value P2 (°) are obtained, and then the amplitude imbalance is obtained by calculating A1-A2, and the phase imbalance is obtained by calculating P1-P2-180°.

[0045] Therefore, this embodiment uses time-division measurement combined with data post-processing to test the unbalance of non-standard shortwave baluns. The test process is simple and does not require a large number of ports on the vector network analyzer, thus reducing the limitation of the number of ports on the balun unbalance test.

[0046] In addition, such as Figure 4 As shown, the second embodiment of the present invention proposes a method for testing the unbalance of a non-standard shortwave balun, which is used to test the shortwave balun using the non-standard shortwave balun unbalance testing device described in the first embodiment. The shortwave balun includes a non-standard unbalanced end and a non-standard balanced end. The testing method includes the following steps: S10. Connect the unbalanced test terminal of the non-standard unbalanced port test fixture to interface A and grounding port D on the non-standard unbalanced terminal; and connect the grounding port D on the non-standard balanced terminal to the metal virtual ground. S20. Connect the balance test terminal of the non-standard balanced port test fixture to interface C and grounding port D on the non-standard balanced terminal, and connect both ends of the load body to interface B and interface D on the non-standard balanced terminal, and read S using a vector network analyzer. 21 The first phase value; S30. Replace one end of the load body connected to interface B on the non-standard balancing terminal with interface C on the non-standard balancing terminal, and replace one end of the balancing test terminal connected to interface C on the non-standard balancing terminal with interface B on the non-standard balancing terminal. Read the values ​​of S using a vector network analyzer. 21 The second phase value; S40. Calculate the amplitude-phase imbalance of the shortwave balun based on the first and second phase values.

[0047] As a further preferred technical solution, the first phase value includes S. 21 The amplitude value A1 and the phase value P1, wherein the second amplitude and phase values ​​include S 21 The amplitude value A2 and the phase value P2; Step S40: Based on the first and second phase values, calculate the amplitude-phase imbalance of the short-wave balun, specifically including: Calculate A1-A2 as the amplitude imbalance of the shortwave balun; Calculate P1-P2-180° as the phase imbalance of the shortwave balun.

[0048] As a further preferred technical solution, a wire drawn from the inner conductor of the second coaxial cable in the unbalanced test terminal is connected to interface A on the non-standard unbalanced terminal, and several wires drawn from the outer conductor of the second coaxial cable in the unbalanced test terminal are uniformly connected to the grounding port D on the non-standard balanced terminal.

[0049] As a further preferred technical solution, a wire leading from the inner conductor of the second coaxial cable is connected to interface C or interface B on the non-standard balance end, and a wire leading from the outer conductor of the second coaxial cable is connected to the grounding port D on the non-standard balance end.

[0050] As a further preferred technical solution, the metal virtual ground is installed at the middle position between interface B and interface C of the non-standard balance end, so that interface B and interface C of the non-standard balance end are symmetrically distributed with respect to the metal virtual ground.

[0051] It should be noted that by installing the metal virtual ground at the midpoint of the physical locations of the two outlet ports B and C of the non-standard balanced port, making ports B and C as symmetrical as possible with respect to the metal virtual ground, and forming a good electrical connection with the ground of the balun balanced port, the influence of the metal virtual ground on the balanced port field can be reduced, thus reducing the inaccuracy of the unbalance measurement.

[0052] It should be noted that in actual testing, the length of the connecting wires used should be as short as possible. For example, the length of the connecting wires between the load and the non-standard balance terminals port B (port C) and port D should be minimized, and the wires led out from the inner and outer conductors of the second coaxial cable to be clamped on port B (port C) and port D should be as short as possible.

[0053] This embodiment uses a 2-port vector network analyzer to test the balun imbalance of an equivalent 3-port network with non-standard ports. The results are as follows: Figure 5 As shown, with Figure 6 A comparison of the simulation results of the balun unbalance shown indicates that the trends and values ​​of the measured results and the simulation results are similar. Therefore, the non-standard shortwave balun unbalance testing device proposed in this embodiment not only effectively reduces the complexity of the test and the cost, but also has high testing accuracy and has great engineering application value.

[0054] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0055] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" or "several" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0057] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A non-standard short-wave balun unbalance testing device, characterized in that, This includes non-standard balanced port test fixtures and non-standard unbalanced port test fixtures, which are respectively connected to the two ports of the vector network analyzer. The non-standard unbalanced port test fixture includes a first coaxial cable connection structure. One end of the first coaxial cable connection structure is the unbalanced test end, and the other end is the first radio frequency end. The first radio frequency end is connected to one port of the vector network analyzer. The non-standard balanced port test fixture includes a metal virtual ground, a load body, and a second coaxial cable connection structure. One end of the second coaxial cable connection structure is the balanced test end, and the other end is the second RF end, which is connected to another port of the vector network analyzer.

2. The non-standard short-wave balun imbalance testing device as described in claim 1, characterized in that, The first coaxial cable connection structure includes a first coaxial cable, one end of which is equipped with a conversion interface to form a radio frequency terminal, and the other end is an unbalanced test terminal. The unbalanced test terminal includes a wire led out from the inner conductor of the first coaxial cable and several wires led out from the outer conductor.

3. The non-standard short-wave balun imbalance testing device as described in claim 1, characterized in that, The second coaxial cable connection structure includes a second coaxial cable, one end of which is equipped with a conversion interface to form a radio frequency end, and the other end is a balanced test end. The balanced test end includes a wire led out from the inner conductor of the second coaxial cable and a wire led out from the outer conductor.

4. The non-standard short-wave balun imbalance testing device as described in claim 2, characterized in that, Several conductors extending from the outer conductor of the first coaxial cable are arranged around a single conductor extending from the inner conductor of the first coaxial cable to enclose the single conductor in the middle.

5. The non-standard short-wave balun imbalance test device as described in claim 2 or 3, characterized in that, The conversion interface adopts an SMA interface or an N-type interface.

6. The non-standard short-wave balun imbalance testing device as described in claim 2 or 3, characterized in that, A metal connector is provided at the end of the conductor.

7. The non-standard short-wave balun imbalance testing device as described in claim 6, characterized in that, The metal connector is a metal clip.

8. The non-standard short-wave balun imbalance testing device as described in claim 1, characterized in that, The two ends of the load body are respectively connected to wires.

9. The non-standard short-wave balun imbalance testing device as described in claim 1, characterized in that, The load value of the load body is the non-standard balanced port impedance value minus the vector network analyzer port impedance value.

10. A non-standard short-wavelength balun unbalance test method, characterized in that, A method for testing a short-wavelength balun unbalance using the non-standard short-wavelength balun unbalance testing device as described in any one of claims 1-9, wherein the short-wavelength balun includes a non-standard unbalanced end and a non-standard balanced end, the testing method comprising: Connect the unbalanced test terminal of the non-standard unbalanced port test fixture to interface A and grounding port D on the non-standard unbalanced terminal; and connect the grounding port D of the non-standard balanced terminal to the metal virtual ground. Connect the balance test terminal of the non-standard balanced port test fixture to interface C and grounding port D on the non-standard balanced terminal, and connect both ends of the load body to interfaces B and D on the non-standard balanced terminal. Then, read the S value using a vector network analyzer. 21 The first phase value; Replace one end of the load body connected to interface B on the non-standard balancing terminal with interface C on the non-standard balancing terminal, and replace one end of the balancing test terminal connected to interface C on the non-standard balancing terminal with interface B on the non-standard balancing terminal. Then read the S value using a vector network analyzer. 21 The second phase value; The amplitude-phase imbalance of the short-wave balun is calculated based on the first and second phase values.

11. The non-standard short-wavelength balun imbalance test method as described in claim 10, characterized in that, The first phase value includes S 21 The amplitude value A1 and the phase value P1, the second amplitude and phase values ​​include S 21 The amplitude value A2 and the phase value P2; The calculation of the amplitude-phase imbalance of the short-wave balun based on the first and second amplitude-phase values ​​includes: Calculate A1-A2 as the amplitude imbalance of the shortwave balun; Calculate P1-P2-180° as the phase imbalance of the shortwave balun.

12. The non-standard short-wavelength balun imbalance test method as described in claim 10, characterized in that, In the unbalanced test terminal, a wire led out from the inner conductor of the second coaxial cable is connected to interface A on the non-standard unbalanced terminal, and several wires led out from the outer conductor of the second coaxial cable in the unbalanced test terminal are evenly connected to the grounding port D on the non-standard balanced terminal.

13. The non-standard short-wavelength balun imbalance test method as described in claim 10, characterized in that, The balance test terminal has a wire leading from the inner conductor of the second coaxial cable connected to interface C or interface B on the non-standard balance terminal, and a wire leading from the outer conductor of the second coaxial cable connected to the grounding port D on the non-standard balance terminal.

14. The non-standard short-wavelength balun imbalance test method as described in claim 10, characterized in that, The metal virtual ground is installed at the midpoint between interface B and interface C of the non-standard balance end, so that interface B and interface C of the non-standard balance end are symmetrically distributed with respect to the metal virtual ground.

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