A method for precise phase synchronization of radio frequency cable assemblies

Abstract

This invention belongs to the field of cable assembly phase matching technology, specifically relating to a method for precise phase synchronization of radio frequency cable assemblies. The invention includes steps such as initially calculating the cable length and cutting the cable; determining the accurate value of the dielectric constant of the cable insulation medium; and assembling the assembly and precisely adjusting the phase matching. This invention ensures that the electrical length and phase remain consistent after the phase matching operation, and can be precisely adjusted according to system design requirements.

Description

Technical Field

[0001] This invention belongs to the field of cable assembly phase matching technology, and specifically relates to a method for precise phase synchronization of radio frequency cable assemblies. Background Technology

[0002] Because phased array radars are highly sensitive to phase parameters, a certain degree of phase consistency is required between the various RF cable assemblies used. Therefore, the RF cable assemblies must have precise electrical lengths (length expressed in terms of electromagnetic wavelength) before and during assembly. To ensure consistency in electrical length between assemblies of the same model, the RF cable assemblies must be phase-matched during assembly. This is typically achieved by accurately cutting, assembling, and testing the mechanical length of each assembly, matching them one by one. The difficulty of component phase matching is directly proportional to the operating frequency and the number of units involved in the phase matching, and inversely proportional to the required phase accuracy.

[0003] Electrical length is a determining factor in the phase of a cable assembly. For N cable units (N≥2) to have consistent phase, they must have consistent electrical lengths. Factors affecting cable electrical length include cable mechanical length, insulation dielectric constant, ambient temperature, and cable bending. Under ideal dielectric conditions and with identical ambient temperature and bending, consistent mechanical lengths can ensure consistent electrical lengths. However, unavoidable dielectric inhomogeneities exist during cable manufacturing. These inhomogeneities stem from factors inherent in the insulation material itself, such as impurities and porosity, as well as factors related to the cable's dielectric structure and manufacturing process. Therefore, traditional methods of ensuring consistent mechanical lengths are insufficient to guarantee consistent electrical lengths; this phase inconsistency becomes more pronounced with longer assemblies. In such cases, high-precision electrical length testing and phase difference calculation methods are needed for auxiliary phase matching. This is a crucial condition for ensuring phase consistency of multi-channel signals in phased array radar. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a phase matching method for radio frequency cable assemblies based on the technology of accurate measurement and calculation of phase difference of multi-channel cable assemblies, ensuring that the electrical length and phase remain consistent after the phase matching operation.

[0005] The technical solution of this invention is: a method for precise phase synchronization of radio frequency cable assemblies, characterized by comprising the following steps:

[0006] Step 1: Calculate the initial cable length and cut the cable accordingly. The formula is as follows:

[0007]

[0008] In equation (1), L0 is the cable cutting length; L1 is the length required by the component design; λ is the wavelength; and ε is the design value of the dielectric constant of the cable insulation medium. It is the cable transmission speed ratio;

[0009] Step 2: Determine the accurate value of the dielectric constant ε1 of the cable insulation medium;

[0010] The third step is to assemble the components and precisely adjust the phase alignment; install the connector at the other end, and after installation, measure the phase of each component, number it, and record it; after analyzing and organizing the data, sort them according to the component phase, formulate an adjustment plan, and implement it. The specific steps are as follows:

[0011] Test and analyze the phase data, and calculate and organize the phase difference;

[0012] Determine the required phase width band of the components along the clockwise direction of the polar coordinates. Using the component with the shortest electrical length as the reference, select the area within the required phase angle band along the clockwise direction. Components falling within this area are qualified. The remaining components are adjusted according to the angle between them and the center position of the angle band.

[0013] Then, the length of cable that needs to be matched and trimmed is calculated according to the formula;

[0014] Finally, precise phase matching is performed based on the trimmed length L2.

[0015] The beneficial effects of the method of this invention are as follows: Traditional RF cable phase matching methods, under ideal dielectric conditions and the same ambient temperature and bending conditions, rely solely on ensuring consistent mechanical length of the cables to guarantee consistent electrical length of the components, i.e., ensuring phase synchronization of the components. However, with the development of phased array radar technology, radar system bandwidth is increasing, the working environment is becoming more complex, and the sensitivity to phase indicators is becoming more and more pronounced. Even if software methods exist to adjust the system phase online, the phase difference measurement algorithm is complex and requires a large amount of hardware resources for computation, which cannot meet the requirements of low power consumption, lightweight, miniaturization, and high reliability of equipment. It is still necessary to start from the basic hardware to achieve adjustable phase of the RF channel. However, there is an unavoidable dielectric inhomogeneity in the manufacturing process of RF cables. This inhomogeneity is due to factors such as the presence of impurities and pores in the insulation material itself, as well as factors such as the cable dielectric structure and manufacturing process. The longer the component length, the more obvious the phase inconsistency caused by this dielectric inhomogeneity becomes. Therefore, the RF cable component phase matching method based on the multi-channel cable component phase difference accurate measurement and calculation technology of this invention can ensure that the RF cable component is not limited by length, and that the electrical length and phase remain consistent after the phase matching operation, and can be precisely adjusted according to the system design requirements. Attached Figure Description

[0016] Figure 1 When matching phases of the cable, cut it shorter in the correct direction.

[0017] Figure 2 Phase angle of a batch of cable assemblies.

[0018] Figure 3 The cable has a 2GHz component phase angle.

[0019] Figure 4 The cable has a 1GHz component phase angle. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0021] like Figures 1 to 3 As shown, a method for precise phase synchronization of a radio frequency cable assembly according to the present invention includes the following steps:

[0022] Step 1: Preliminary Calculation and Cutting of Cable. Based on the required length and frequency of the components to be used, cut the cable from the reel. The cut length is generally the sum of the required cable length and the mechanical length of the cable for at least one wavelength of the upper limit frequency. The formula is as follows:

[0023]

[0024] In equation (1), L0 is the cable cutting length; L1 is the length required by the component design; λ is the wavelength; and ε is the design value of the dielectric constant of the cable insulation medium. It is the cable transmission speed ratio. This is a margin for the length of the phase to be matched.

[0025] Step 2: Determine the accurate dielectric constant ε1 of the cable insulation medium and further trim the cable to a consistent electrical length. After completing Step 1, install the connector at one end, leaving the other end open. After assembly, measure the electrical length of the assembly using the time-domain characteristic curve of a vector network analyzer. The open-circuit end of the cable will exhibit a higher peak value in the time-domain curve, making it easier to detect. Therefore, by using a network analyzer to determine the location of the open-circuit end of the assembly, the electrical length data of the cable is determined, thereby verifying the accurate dielectric constant ε1 of the cable insulation medium and calculating the actual cable transmission speed ratio. Then, a network analyzer was used to test the electrical length of all components that need to be matched, i.e., the position from the open circuit point to the signal output terminal, and the electrical length of all components that need to be matched was cut to match the shortest component.

[0026] The third step is to assemble the components and precisely adjust the phase alignment. Install the connector at the other end. After installation, measure the phase of each component, number it, and record it. After analyzing and organizing the data, sort the components by phase, formulate an adjustment plan, and implement it. The specific steps are as follows:

[0027] First, test the phase data and analyze it to calculate and sort out the phase difference. At a certain frequency, the longer the cable, the more lagging the phase, that is, the longer the mechanical length of the cable, the smaller the phase, and vice versa. When reflecting the phase on the polar coordinate, when the length of the cable assembly is shortened by one wavelength each time, its phase angle increases by 360° in the counterclockwise direction. Therefore, when matching the phase of the cable assembly, the cable is cut short in the counterclockwise direction. When testing the phase with a network analyzer, the phase angle displayed is within the range of 0 to ±180° of the last cycle wavelength. For the sake of intuitive understanding, the phase is reflected as shown in Figure 1 as shown.

[0028] Determine the phase width band of the components required for phase matching along the clockwise direction of the polar coordinate, that is, taking the component with the shortest electrical length as the reference, select the area within the required phase angle band along the clockwise direction, and the components falling within this area are qualified, and the remaining components are trimmed according to the included angle degrees between them and the center position of this angle band. For example, it is known that the phase requirement of a certain batch of components at a certain frequency point is ±4°. After assembly, their phase angles are distributed in the shaded area shown in Figure 2 as shown (100° to -176°). The phase of the shortest component is -176°. Rotate 8° angle band clockwise, that is, the components in the slanted shaded part in Figure 2 (176° to -176°) are all qualified components, and the components in the crosshatched shaded part (100° to 176°) need to be corrected. The included angle corresponding to the corrected length depends on the included angle between the component phase and the midline position (180°) of the slanted area. Here, the midline position (180°) of the slanted area can be understood as the phase position of the standard part, as shown in Figure 2 as shown.

[0029] Then, calculate the cable length L2 that needs to be trimmed for phase matching according to the formula. The specific calculation method is to first calculate the component wavelength according to formula (2), and then calculate the length L2 to be cut short by formula (3).

[0030]

[0031] L2 = β / 360 × λ1 (3)

[0032] In the formula, λ1 is the actual wavelength (unit: mm); ε1 is the actual relative permittivity of the insulating medium measured in the second step, β is the phase angle between the test cable and the standard cable; f is the signal frequency (unit: Hz); L is the trimming length (unit: mm); is the actual cable transmission speed ratio.

[0033] Finally, precise phase matching is performed based on the trimmed length L2. One connector is removed, and the corresponding dielectric dimension L2 is cut off with a blade. The connector body is then reassembled by soldering, and the phase is retested. In actual phase matching, the cutting length for each correction can be set to L2 / 2. This iterative correction and approximation method reduces the probability of phase matching failure and saves manufacturing materials. Cable assemblies should be numbered and recorded during the process. The phase is tested after each correction. If it meets the requirements, the phase matching work is complete. Otherwise, a new correction plan should be calculated and the cable corrected until the cable assembly phase meets the requirements.

[0034] Based on the RF cable assembly phase matching method mentioned above, which is based on the precise measurement and calculation technology of phase step difference of multi-channel cable assembly, the basic phase modulation parameters of RF cable assemblies in each frequency band can be obtained, as detailed in the table below.

[0035]

[0036] As shown in the table, signals below 2GHz can have their phase adjusted by cutting the center dielectric of the cable with a blade. However, signals above 4GHz are very sensitive to phase changes and can only be corrected by adjusting the tightness of the connector pins. The inner and outer conductors of the connector are in a state similar to the mating of pins and sockets. The entire connector is telescopic and movable, with air insulation typically used for the movable section. By changing the contact length between the two conductors, the overall electrical length is adjusted to achieve phase adjustment. This method is generally suitable for high-frequency applications requiring precise phase adjustment.

[0037] The following is an example of cable fabrication, including the following steps:

[0038] Step 1: Calculate the cable length and cut the cable. Based on the required length (5 meters) and frequency (1 GHz) of the components to be used, cut the cable from the reel. The cutting length is generally the sum of the required cable length and the mechanical length of the cable for at least one wavelength of the upper limit frequency. According to formula (1):

[0039] L0 = 5000 + 126 × 0.8 = 5126 mm

[0040] Step 2: Measure the accurate dielectric constant ε1 of the cable and preliminarily cut the cable to the same electrical length. On the basis of completing the work of the first step, install the connector at one end first, and keep the other end open. Connect the component with the connector installed at one end to the test end of the network analyzer. Vector network analyzers all have the function of setting the equivalent dielectric constant. First, set an approximate value of 1.562 for the equivalent dielectric constant of the tested cable. Then, determine the position of the open point in the time-domain characteristic curve of this cable. Its value may be approximately equal to the mechanical length of the cable. Use the network analyzer to capture and track the position of the open point in the characteristic curve, and repeatedly correct the value of the equivalent dielectric constant until the length displayed by the instrument is the same as the mechanical length of the cable. At this time, the dielectric constant value of 1.416 displayed on the instrument is the relatively accurate equivalent dielectric constant value of this cable, and the cable transmission speed ratio is 0.84. Then use the network analyzer to measure the electrical lengths of all the components that need to be phase-matched, that is, the positions from the open point to the signal output end, and cut the electrical lengths of all the components that need to be phase-matched to be the same as that of the component with the shortest electrical length.

[0041] Step 3: Assemble the components and precisely trim the phase matching. Install the connector at the other end. After installation, measure the phase of each component and make records. After analyzing and sorting out the data, sort them according to the component phases, formulate a trimming plan and implement it. The specific steps are as follows:

[0042] First, test the phase data and analyze it, and calculate and sort out the phase difference. At a certain frequency, the longer the cable, the more lagging the phase, that is, the longer the mechanical length of the cable, the smaller the phase, and vice versa. When reflecting the phase on the polar coordinate, when the length of the cable component is shorter by one wavelength, its phase angle increases by 360° in the counterclockwise direction. Therefore, when phase-matching the cable components, cut the cable shorter in the counterclockwise direction.

[0043] Determine the phase width band of the components that need to be phase-matched along the clockwise direction of the polar coordinate, that is, take the component with the shortest electrical length as the reference, draw the area within the required phase angle band along the clockwise direction, and the components falling within this area are all qualified, and the remaining components are trimmed according to the included angle between their positions and the center position of this angle band. For example, it is known that the phase requirement of a certain batch of components at a certain frequency point is ±4°. After assembly, their phase angles are distributed in the shaded area shown in Figure 2 (100°~-176°). The phase of the shortest component is -176°. Rotate clockwise by an 8° angle band, that is, Figure 2 the components in the slant-shaded area (176°~-176°) in are all qualified components, and the components in the cross-shaded area (100°~176°) need to be corrected. The included angle corresponding to the corrected length depends on the included angle between the component phase and the mid-line position (180°) of the slant-shaded area. Here, the mid-line position (180°) of the slant-shaded area can be understood as the phase position of the standard component. As shown in Figure 2As shown.

[0044] Then, the cable length L2 that needs to be trimmed is calculated according to the formula. The specific calculation method is to first calculate the component wavelength according to formula (2), and then calculate the length L2 that should be shortened according to formula (3).

[0045] The operating frequency of a certain cable assembly is 1-2 GHz, and the cable transmission speed ratio is 0.84 (ε1 is the actual dielectric constant of the insulating medium measured in step two). (This is the actual cable transmission speed ratio), and the phase of the two cable assemblies was measured as shown in Table 1.

[0046] Table 1 Phase of the two cable assemblies

[0047]

[0048] The phase positions of the two cable assemblies in polar coordinates are as follows: Figure 3 and Figure 4 As shown, after analysis, it was determined that cable #1 should be cut. The required cutting length can be calculated using formulas (2) and (3):

[0049] λ1=126mm

[0050] L2 = 126 / 360 × 20 = 7mm

[0051] Based on the upper limit of 2GHz, and with a phase angle of β≈20°, 1° corresponds to a cable mechanical length of approximately 0.35mm. Therefore, it is calculated that cable assembly #1 should be shortened by 7mm.

[0052] Finally, precise phase matching is performed based on the trimmed length L. One connector is removed, and the corresponding dielectric dimension L2 is cut off with a blade. The connector body is then reassembled by soldering, and the phase is retested. In actual phase matching, the cutting length for each correction can be set to L2 / 2. This iterative correction and approximation method reduces the probability of phase matching failure and saves manufacturing materials. Cable assemblies should be numbered and recorded during the process. The phase is tested after each correction. If it meets the requirements, the phase matching work is complete. Otherwise, a new correction plan should be calculated and the cable corrected until the cable assembly phase meets the requirements.

Claims

1. A method for phase accurate synchronization phasing of radio frequency cable assemblies, characterized by: The method comprises the following steps: First step: preliminary calculation of cable length and blanking, the formula is as follows: L0 = L1 + λ x 1 (1) In formula (1), L0 is the cable cutting length; L1 is the length required by the component design; λ is the wavelength; ε is the design value of the dielectric constant of the cable insulation medium; 1 / is the cable transmission speed ratio; Second step: determination of the accurate value of the dielectric constant of the cable insulation medium ; The measuring step is: one end of the cable is installed with a connector, the other end is kept open circuit, after the assembly is completed, the electrical length of the assembly is measured by the time domain characteristic curve of the vector network analyzer; the open circuit end of the assembly is measured by the network analyzer, the electrical length data of the cable is determined, so as to approve the accurate dielectric constant of the cable insulation medium ​ Third step, assemble the component and accurately trim the phase; install the connector of the open circuit state end, after installation, measure the phase of each component and number and record; after data analysis and arrangement, sort according to the component phase, make the trimming scheme and implement, the specific steps are as follows: Test the phase data and analyze, calculate and arrange the phase difference; Determine the component phase width band of the required phase along the polar coordinate clockwise direction, take the component with the shortest electrical length as the reference, select the area within the required phase angle band along the clockwise direction, the components falling in the area are qualified, and the remaining components are trimmed according to the included angle degree of the center position of the angle band; Then, calculate the cable length that needs to be trimmed for phase matching; Trimming cable length The calculation method is that, λ1 = c / f x 1 ; = β / 360 x λ1; where λ1 is the actual wavelength; is the actual dielectric constant of the insulation medium measured in step two, β is the phase angle between the test cable and the standard cable; and f is the signal frequency. is the length of the test cable; and c is the speed of light. Finally, the length of the trimming cable is adjusted according to the trimming cable length The phase is accurately matched, and the trimming cable length is adjusted by setting the cutting length of each phase adjustment to 1 / 2, and adjusting the phase in an iterative and successive approximation manner.

2. The method of claim 1, wherein: The signal cable component below 2GHz adjusts the phase by cutting the cable center medium with a blade.

3. The method of claim 1, wherein: the phase of the RF cable assembly is precisely synchronized by: determining a phase difference between the phase of the RF cable assembly and the phase of the RF signal; and adjusting the phase of the RF cable assembly to match the phase of the RF signal. The signal cable component above 4GHz adjusts the phase by adjusting the tightness of the connector pin of the cable component.

Images