A method of compensating for impedance discontinuity in a radio frequency SMP connector

Abstract

The present application relates to a kind of radio frequency SMP connector impedance discontinuity compensation method, belong to radio frequency communication field, solve the impedance discontinuity caused by split slot in prior art, cause signal time delay, reflection, destroy signal integrity Problem.A kind of radio frequency SMP connector impedance discontinuity compensation method, comprising the following steps: the width of connector split slot is regarded as the short-circuit line of parallel same length, the parasitic inductance generated by split slot is calculated;According to parasitic inductance, distribution inductance when not compensating, distribution capacitance, split slot length, quantity and connector characteristic impedance, obtain compensation distribution capacitance;Based on distribution capacitance calculation equation and compensation distribution capacitance, obtain inner conductor diameter compensation value;According to impedance consistency principle, based on inner conductor diameter compensation value, obtain equivalent dielectric constant;Based on equivalent dielectric constant and the dielectric constant calculation model of composite medium, obtain insulating medium correction diameter.Electrical compensation to connector is realized, so as to ensure the integrity of signal.

Description

Technical Field

[0001] This invention relates to the field of radio frequency communication technology, and in particular to a method for compensating for impedance discontinuities in radio frequency SMP connectors. Background Technology

[0002] Radio frequency SMP connectors (Subminiature Push, SMP) are widely used in microwave systems, and the signal integrity issues during transmission have received widespread attention from scholars.

[0003] Electrical compensation design typically relies on iterative simulations over a wide range. For example, Wang et al., based on long-line theory, conducted a compensation design for the soldering area between microstrip lines and SMP connectors using simulations; Huang et al. calculated the impact of BGA solder joint morphology on signal integrity using HFSS. However, these studies did not summarize universal formulas or calculate the parameter optimization range, and the compensation design is only applicable to specific situations. To address these issues, Somlo et al. proposed a design scheme suitable for capacitive compensation of structural steps, providing an empirical calculation formula based on the concept of stepped capacitance. However, the calculation is complex and accuracy is difficult to guarantee, and it is not applicable to elastic slotting inductive compensation. Sharma used software to calculate the relationship curve between compensation value and slotting depth and number of slots, but did not provide a compensation calculation scheme for elastic slotting.

[0004] Therefore, there is an urgent need for a method to compensate for the impedance discontinuity of RF SMP connectors that solves the above problems.

[0005] Because the parasitic electrical parameters generated after slotting involve Besel and Neumannm functions and transcendental equations, the specific solution methods are too complex. Other scholars have summarized the influence of slotting on characteristic impedance as follows:

[0006] Z0%=+12.5×N(l / d) 2 ×100%

[0007] The radius compensation value obtained from this is as follows:

[0008] d1 = +2.6Nl 2 d

[0009] However, these formulas only explain the physical phenomenon that the outer diameter of the inner conductor needs to be increased and the inner diameter of the outer conductor needs to be decreased, but they do not explain the underlying substance of the compensation. Furthermore, incorporating factors such as frequency, dielectric constant, and transmission distance into the constant 2.6 based on empirical summaries lacks theoretical basis, and the compensation value may be inaccurate.

[0010] SMP connector interfaces utilize a slotted design to create a self-locking, elastic structure. While this improves assembly efficiency, it also introduces impedance discontinuities, causing signal delays, reflections, and compromising signal integrity. Therefore, electrical compensation measures must be designed for the discontinuities at the slotted sections to ensure signal integrity. Summary of the Invention

[0011] Based on the above analysis, the present invention aims to provide a method for compensating for impedance discontinuities in RF SMP connectors, in order to solve the problem in the prior art where impedance discontinuities caused by slotting result in signal delay, reflection, and damage to signal integrity.

[0012] On one hand, embodiments of the present invention provide a method for compensating for impedance discontinuities in an RF SMP connector, comprising the following steps:

[0013] The connector slot width is considered as a short circuit of the same length in parallel, and the parasitic inductance generated by the slot is calculated according to the short-circuit load input impedance formula.

[0014] The actual compensated distributed capacitance is obtained based on the parasitic inductance, the uncompensated distributed inductance and distributed capacitance of the connector, the slot length, the number of slots, and the characteristic impedance of the connector.

[0015] Based on the distributed capacitance calculation equation and the actual compensated distributed capacitance, the inner conductor diameter compensation value is obtained;

[0016] Based on the impedance consistency principle, the equivalent dielectric constant required to achieve impedance consistency is obtained based on the connector characteristic impedance equation and the inner conductor diameter compensation value; the corrected diameter of the insulating medium is obtained based on the equivalent dielectric constant and the dielectric constant calculation model of the composite medium.

[0017] Furthermore, the formula for the short-circuit load input impedance is:

[0018] L1=jZ0tanβl

[0019] Where L1 is the parasitic inductance, Z0 is the characteristic impedance of the connector, β is the phase shift constant, and l is the slot width.

[0020] Furthermore, the compensation distributed capacitance is obtained based on the parasitic inductance, the uncompensated distributed inductance and distributed capacitance of the connector, the slot length, the connector characteristic impedance, and the connector characteristic impedance equation, specifically as follows:

[0021]

[0022] Where C0 is the uncompensated distributed capacitance, L0 is the uncompensated distributed inductance, X is the slot length, C2 is the actual compensated distributed capacitance, and N is the number of slots.

[0023] Furthermore, the formulas for calculating the uncompensated distributed capacitance and uncompensated distributed inductance are as follows:

[0024]

[0025]

[0026] Where ε0 is the vacuum permittivity, ε r μ is the relative permittivity of the insulating medium, μ0 is the free permeability, and μ r Let be the relative permeability of the insulating medium, D be the inner diameter of the outer conductor, and d be the outer diameter of the inner conductor without compensation; ε0 = 8.854 F / m, μ0 = 4π × 10⁻⁶ -7 N / A 2 .

[0027] Furthermore, the inner conductor diameter compensation value is obtained based on the distributed capacitance calculation equation and the compensated distributed capacitance, specifically as follows:

[0028]

[0029] Where d1 is the inner conductor diameter compensation value, and A is 5.56 × 10⁻⁶. -11 ε r .

[0030] Furthermore, the process of obtaining the equivalent dielectric constant required for impedance consistency based on the connector characteristic impedance equation and the inner conductor diameter compensation value, according to the impedance consistency principle, includes the following steps:

[0031] Based on the uncompensated distributed capacitance and distributed inductance, the characteristic impedance formula is obtained:

[0032]

[0033] The formula for the characteristic impedance after compensation is:

[0034]

[0035] Therefore, we get:

[0036]

[0037] Furthermore, the corrected diameter of the insulating medium is obtained from the calculation model based on the equivalent dielectric constant and the dielectric constant of the composite medium, specifically as follows:

[0038]

[0039] Where, ε total ε is the equivalent dielectric constant. PTFE ε is the dielectric constant of the insulating medium. Aird is the dielectric constant of air. in The diameter is corrected for the insulating medium.

[0040] Furthermore, the formula for calculating the phase velocity is:

[0041]

[0042] Where Vp is the phase velocity, ω is the real frequency, and β is the phase shift constant.

[0043] Furthermore, the method also includes using the calculated inner conductor diameter compensation value d1 and the insulation dielectric corrected diameter d in Using the initial values, a high-frequency electromagnetic field simulation is performed on the connector to conduct a small-range search, resulting in a more optimized inner conductor diameter compensation value and insulation medium correction diameter.

[0044] Furthermore, the connector is a coaxial RF connector with a characteristic impedance of 50Ω.

[0045] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0046] 1. The flexible slot introduces parasitic inductance, which can be calculated as the equivalent of the short-circuit length, increasing the outer diameter of the inner conductor, maintaining the continuity of characteristic impedance, and realizing electrical compensation;

[0047] 2. This application proposes an equivalent method based on short-circuit to obtain an approximate value of the parasitic inductance caused by the slot, and derives a convenient calculation method for the compensation diameter of the inner conductor's outer diameter through transmission parameters. The compensation diameter has a small deviation, does not introduce unnecessary capacitance parameters, and does not produce high-frequency reflection peaks.

[0048] 3. The electrical performance of the compensation design based on this application is superior to that of empirical compensation. It is applicable to RF SMP connectors with different slot widths and wide frequency domains. The calculated values ​​can be used directly under low-frequency operating conditions. Under high-performance requirements, the calculation method of this scheme can effectively determine the initial simulation values, narrow the parameter search range, and improve the design efficiency and electrical performance of SMP connectors.

[0049] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from the description and drawings, which are particularly pointed out. Attached Figure Description

[0050] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0051] Figure 1 This is a flowchart of a method for compensating impedance discontinuities in an RF SMP connector.

[0052] Figure 2 This is a schematic diagram of a slotted connection;

[0053] Figure 3 This is a schematic diagram of a three-dimensional model of an elastic grooving device.

[0054] Figure 4 This is a diagram showing the standing wave ratio distribution as the diameter of the insulating medium changes;

[0055] Figure 5 The VSWR distribution under different compensation conditions;

[0056] Figure 6 The characteristic impedance curves of TDR are shown for three different cases.

[0057] Figure 7 The results are the optimization results for the radius parameter of the insulating medium;

[0058] Figure 8 The standing wave ratio distribution for different inner conductor diameters;

[0059] Figure 9 This is a schematic diagram of the compensation for the outer diameter of the inner conductor based on empirical compensation and the compensation scheme of this application;

[0060] Figure 10 The VSWR curve is based on empirical data and the compensation scheme of this application. Detailed Implementation

[0061] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0062] Example 1

[0063] A specific embodiment of the present invention discloses a method for compensating for impedance discontinuities in an RF SMP connector, such as... Figure 1 As shown. Includes the following steps:

[0064] The connector slot width is considered as a short circuit of the same length in parallel, and the parasitic inductance generated by the slot is calculated according to the short-circuit load input impedance formula.

[0065] The actual compensated distributed capacitance is obtained based on the parasitic inductance, the uncompensated distributed inductance and distributed capacitance of the connector, the slot length, the number of slots, and the characteristic impedance of the connector.

[0066] Based on the distributed capacitance calculation equation and the actual compensated distributed capacitance, the inner conductor diameter compensation value is obtained;

[0067] Based on the impedance consistency principle, the equivalent dielectric constant required to achieve impedance consistency is obtained based on the connector characteristic impedance equation and the inner conductor diameter compensation value; the corrected diameter of the insulating medium is obtained based on the equivalent dielectric constant and the dielectric constant calculation model of the composite medium.

[0068] Subminiature Push (SMP) connectors are widely used in microwave systems, and the signal integrity issues during transmission have attracted considerable attention from researchers. While the SMP connector interface uses a slotted design to create a self-locking elastic structure, this improves assembly efficiency but also introduces impedance discontinuities, causing signal delays and reflections, thus compromising signal integrity. Therefore, electrical compensation measures must be designed for the discontinuities at the slotted sections to ensure signal integrity.

[0069] Specifically, after a slot is created at the interface of an SMP connector, the induced magnetic field effect generated by the alternating current near the width of the inner conductor slot is enhanced, resulting in parasitic inductance. If the relative permittivity ε r When the inner conductor's outer diameter changes, its characteristic impedance changes accordingly, leading to impedance mismatch between the load and the connector, resulting in reflected waves and disrupting signal integrity. Regarding mechanical reliability, the small size of the connector's inner conductor further deteriorates structural stability after slotting. Therefore, adjustments to the inner conductor structure are necessary to achieve structural reinforcement and electrical compensation. The specific formula for calculating reflected waves is:

[0070]

[0071] Where Γ is the reflection coefficient, Z L Z0 is the load impedance (Ω), Z0 is the characteristic impedance of the connector (Ω), β is the phase shift constant (rad / m), and z is the connector reflection length (m). The distance from the starting point to the ending point is the connector reflection length, with the starting point being the center of the connector interface and any point on the axis between the starting point and the intersection of the other end face of the connector and the central axis of the connector.

[0072] Parasitic inductance is caused by slotting and is used to eliminate harmful values. The compensation diameter introduces additional step capacitance, which counteracts the parasitic inductance.

[0073] To calculate the additional parasitic inductance introduced by the slot, the short-circuit equivalent method is used. The slot of a certain width added to the inner conductor is considered as a short-circuit path of equal length connected in parallel. The parasitic inductance value generated by the slot is calculated based on the slot width and the short-circuit load input impedance formula; the short-circuit load input impedance formula is:

[0074] L1=jZ0tanβl (2)

[0075] Where L1 is the parasitic inductance (H) and l is the slot width (m).

[0076] Specifically, according to microwave transmission line theory, the short-circuit input impedance Z in The calculation formula is as follows:

[0077]

[0078] Z in Vp is the short-circuit input impedance (Ω), Vp is the phase velocity (m / s), and jω is the frequency domain.

[0079] When the length of the parallel short path is less than λ P At / 4, it belongs to pure inductive reactance. Due to the small slot width, it is equivalent to a short parallel short-circuit length, and the tanβl term is an infinitesimal term. According to the equivalent infinitesimal tanβl, it can be approximated as βl. At the same time, the impedance has λ P / 4 Transformation and λ P / 2 periodicity, when the groove length or the groove influence area is much smaller than λ P When the value is 4, the influence of the frequency domain can be ignored, and it can be regarded as a uniform impedance distribution line.

[0080] λ P The phase wavelength, i.e., the free-space electromagnetic wave wavelength λ0 and the relative permittivity ε r 1 / 2 The quotient, expressed by the formula:

[0081]

[0082] Where C0 is the uncompensated distributed capacitance (F), and f is the frequency;

[0083] Wavelength is inversely proportional to frequency. Currently used SMP connectors mostly use polytetrafluoroethylene (PTFE) as the insulating medium, with a dielectric constant of 2.1. At the highest operating frequency of 65GHz, λ... P The width is 0.796 mm, far exceeding the conventional design range of slot width (0, 0.25 mm); if air insulation is selected, the dielectric constant ε r Decrease, phase wavelength λ P Increase, λ P / 4 is much larger than the slot width; conventional SMP connectors are used at frequencies of 18GHz and 40GHz, with a phase wavelength λ. P Increase, λ P / 4 is much larger than the slot width; when the slot width of some specially designed slots exceeds λ P / 4, this scheme is no longer applicable.

[0084] The increased parasitic inductance at the slotted area necessitates the use of capacitive low impedance compensation instead of the classic high impedance compensation.

[0085] Specifically, at lower frequencies, parasitic inductance can be ignored. This is because Vp is relatively high, and electrical performance requirements are lower, allowing for some sacrifice in electrical performance and reducing design complexity. However, under conditions of extreme sensitivity to high-frequency millimeter waves, electrical compensation is necessary. After obtaining the parasitic inductance value, additional distributed capacitance needs to be provided through structural adjustments. According to the formula for calculating distributed capacitance without compensation, increasing the distributed capacitance requires either increasing the outer diameter of the inner conductor, decreasing the inner diameter of the outer conductor, or increasing the relative permittivity. However, since the inner diameter of the outer conductor is a standard value, compensation is generally achieved by increasing the outer diameter of the inner conductor.

[0086] Furthermore, the formulas for calculating the uncompensated distributed capacitance and uncompensated distributed inductance are as follows:

[0087]

[0088]

[0089] Where L0 is the uncompensated distributed inductance (H), ε0 is the vacuum permittivity, and ε r μ is the relative permittivity of the insulating medium, μ0 is the permeability of free space, and μ r Let be the relative permeability of the insulating medium, D be the inner diameter of the outer conductor, and d be the outer diameter of the inner conductor without compensation; ε0 = 8.854 F / m, μ0 = 4π × 10⁻⁶ -7 N / A 2 .

[0090] Specifically, to determine the increase in the outer diameter of the inner conductor, it is necessary to first calculate the compensation distributed capacitance and add the parasitic inductance caused by the slotting to the impedance characteristic expression; the impedance characteristic expression is:

[0091]

[0092] The impedance characteristics after adding parasitic inductance are:

[0093]

[0094] Among them, L total For the overall equivalent inductance (H), C totalC1 is the overall equivalent capacitance (F) and C2 is the theoretical compensation distributed capacitance.

[0095] The above formula can be rearranged as follows:

[0096]

[0097] Since the number of slots affects the compensation capacitance, dividing the calculated value of C1 by the number of slots N yields the actual compensation distributed capacitance:

[0098]

[0099] Where X is the length of the slot (m), C2 is the actual compensated distributed capacitance (F), and N is the number of slots.

[0100] Specifically, let A = 2πε r Substituting ε0 = 8.854 F / m into the equation, we get A = 5.56 × 10⁻⁶. -11 ε r The actual compensated distributed capacitance is:

[0101]

[0102] Furthermore, the inner conductor diameter compensation value is obtained based on the distributed capacitance calculation equation and the actual compensated distributed capacitance, specifically as follows:

[0103]

[0104] Where d1 is the inner conductor diameter compensation value (m);

[0105] Specifically, the derivation process of the actual compensated distributed capacitance and inner conductor diameter compensation values ​​is as follows:

[0106]

[0107]

[0108] ∴AC0=C0(C0+C2)lnD-C0(C0+C2)lnd-AC2

[0109]

[0110]

[0111]

[0112]

[0113]

[0114]

[0115]

[0116]

[0117] Specifically, if applied to low-frequency applications, the outer diameter of the inner conductor at the slot can be increased directly based on the calculated inner conductor diameter compensation value to achieve the compensation purpose.

[0118] For applications requiring high performance, the optimal value can be determined through a small-range parameter search using electrical simulation based on the currently calculated inner conductor diameter compensation value. For example, high-frequency simulation can be performed using electromagnetic simulation software to obtain the optimal value. The electromagnetic simulation software could be CST or HFSS, etc.

[0119] Furthermore, the process of obtaining the equivalent dielectric constant required for impedance consistency based on the connector characteristic impedance equation and the inner conductor diameter compensation value, according to the impedance consistency principle, includes the following steps:

[0120] According to the characteristic impedance formula:

[0121]

[0122] The formula for the characteristic impedance after compensation is:

[0123]

[0124] Therefore, we get:

[0125]

[0126] Specifically, when the size of the insulating medium remains constant, the inner conductor compensation value d1 is added to the characteristic impedance expression at the non-parasitic inductance location to obtain the compensated characteristic impedance. To maintain a constant characteristic impedance, the structure or size of the insulating medium at the interface needs to be readjusted so that the relative permittivity ε at the non-parasitic inductance location is... r Reduced to meet the requirement of characteristic impedance consistency.

[0127] Furthermore, the corrected diameter of the insulating medium is obtained from the calculation model based on the equivalent dielectric constant and the dielectric constant of the composite medium, specifically as follows:

[0128] The dielectric constant calculation model for composite media is as follows:

[0129]

[0130] Where, ε total ε is the equivalent dielectric constant. PTFE ε is the dielectric constant of the insulating medium. Aird is the dielectric constant of air. in The diameter is corrected for the insulating medium.

[0131] The equivalent dielectric constant ε calculated in the previous step total Substituting into the above calculation model, we can obtain the corrected diameter d of the insulating medium. in .

[0132] Specifically, if the actual operating frequency of the RF connector is low, the calculated d1 and d2 can be used directly. in Design structure and compensation. If the RF connector operates at a high frequency, the estimated correction diameter d can be used. in The calculated compensation value d1 is set as the initial value for simulation. This value is then used in high-frequency simulation for a small-range search to obtain new compensation values ​​for the insulating medium size and the inner conductor diameter. This avoids the inaccuracies of empirical formulas, provides an initial value reference for high-frequency simulation, and improves design efficiency and accuracy.

[0133] Furthermore, the formula for calculating the phase velocity is:

[0134]

[0135] Where ω is the real frequency and β is the phase shift constant.

[0136] Furthermore, the connector is a coaxial RF connector with a characteristic impedance of 50Ω.

[0137] Example 2

[0138] This embodiment is provided to verify the accuracy of the method in this application.

[0139] Specifically, such as Figure 2 As shown, the inner conductor front end interface of an SMP connector requires 2 to 8 identical slots with tapering to meet contact stress requirements. For connectors used in the Ka-band (27–40 GHz), the inner conductor is relatively thin; too many slots would significantly reduce mechanical performance, therefore a double-slot structure is generally used. In a certain interface double-slot SMP connector, without compensation, the inner conductor outer diameter is 0.8 mm, the slot width is 0.15 mm, and the slot length is 1.5 mm.

[0140] The phase velocity expression is derived from the formula for the input impedance of a short-circuit load:

[0141]

[0142] Among them, C 光 The speed of light in vacuum (m / s);

[0143] Vp and the dielectric constant ε at the interface rTherefore, the dimensions of the insulating medium at the interface must be determined first. Referring to national standards, the inner diameter D of the connector's outer conductor is available in five sizes: 3.5mm, 2.92mm, 2.4mm, 1.85mm, and 1mm. Since the compensation value d1 of the inner conductor's outer diameter is relatively small compared to the initial value d, the dielectric constant is calculated based on the initial value of 0.8mm. Based on the relationship between the five outer conductor inner diameters D and d, and with a fixed characteristic impedance of 50Ω, the required dielectric constant is calculated using the characteristic impedance formula. The calculation results are shown in Table 1.

[0144] Table 1 Selection Scheme for Outer Conductor Inner Diameter

[0145]

[0146]

[0147] As shown in Table 1, when using an outer conductor inner diameter of 2.920mm or 3.500mm, the required dielectric constant is greater than that of PTFE, which is impractical. When using an outer conductor inner diameter of 1.850mm, the required dielectric constant is close to 1, meaning that most of the insulating medium is air, but the SMP connector interface should have insulating support, thus failing to meet the requirements. When using an outer conductor inner diameter of 1.000mm, the required dielectric constant is less than 1, which is practically impossible. Therefore, an outer conductor inner diameter of 2.400mm must be selected, and the required relative dielectric constant is 1.738 without compensation. According to the dielectric constant calculation model of composite media, the radius of the PTFE medium at this time can be calculated to be approximately 0.983mm. Furthermore, it should be noted that the calculated insulating medium diameter is based on the uncompensated outer diameter of the inner conductor; therefore, a slight adjustment is needed after determining the compensation value. Since the compensation value is small, the adjustment value of the insulating medium can be ignored under non-military or aerospace performance requirements.

[0148] Based on Table 1, neglecting dimensions, the compensation value for the outer diameter of the inner conductor is calculated to be 0.0936 mm, approximately 0.1 mm, using an empirical formula. The empirical formula is as follows:

[0149] d1 = +2.6Nl 2 d (19)

[0150] Using the compensation calculation scheme of this application, the relative permittivity ε r＝ 1.738, C 光 =3×10 8 Substituting m / s into the phase velocity expression, we get Vp = 2.276 × 10 8 Given m / s, l = 0.15 mm, Z0 = 50 Ω, and substituting these values ​​into the short-circuit input impedance, we obtain the parasitic inductance L1 = 3.295 × 10⁻⁶ m / s. -11H. Based on D = 2.4mm and d = 0.8mm, using the expressions for the distributed inductance and distributed capacitance before compensation, L0 = 2.197 × 10⁻⁷ H / m and C0 = 8.796 × 10⁻⁷ H / m. -11 F / m. Referring to the calculation formulas for actual compensation distributed capacitance and inner conductor diameter compensation, substituting the slot length X = 1.5mm, we can obtain the actual compensation distributed capacitance C2 = 4.363 × 10⁻⁶. -12 F / m, inner conductor diameter compensation value d1=0.043mm.

[0151] Specifically, such as Figure 3 The figure shows a simulation model of the elastic slot. The diameter of the interface insulating medium is set to 0.900–1.100 mm (inclusive). Electrical performance distributions for three cases—uncompensated, empirically compensated, and compensated based on this application—are obtained through parameter scanning. Figure 4 As shown.

[0152] Figure 4 (a) When the inner conductor is not compensated, Figure 4 (b) Empirical compensation for sampling of the inner conductor, Figure 4 (c) The inner conductor is compensated using the scheme of this application. Numerically, the extreme value distribution of empirical compensation is similar to that of uncompensated conductors; in fact, the reflection effect is exacerbated when the insulation medium is mismatched (insulation medium diameter 1–1.1 mm), increasing the VSWR. Under optimal conditions, the average VSWR of the uncompensated inner conductor is lower than that of the empirically compensated one. Furthermore, in terms of curve shape distribution, empirical compensation introduces a second peak in the high-frequency region, failing to guarantee the uniformity of electrical performance across a wide bandwidth. It should be noted that the VSWR values ​​of the uncompensated inner conductor remain low when the insulation medium diameter is 1.050 mm or 1.000 mm. This is because, according to the characteristic impedance formula, when the characteristic impedance remains constant, the parasitic inductance L1 caused by the slotting can be compensated not only by increasing the capacitance C but also by increasing ε. r This is used for compensation. When the diameter of the insulating medium increases, the proportion of air volume decreases, which is equivalent to increasing ε. r This cancels out the parasitic inductance effect. However, compared to the compensation method of thickening the inner conductor, increasing ε... r Compensation methods can only ensure impedance consistency and reduce the reflection coefficient, but they increase insertion loss, decrease cutoff frequency, and cannot improve structural mechanical reliability.

[0153] Depend on Figure 4(c) It is evident that when the inner conductor adopts the compensation value based on this application, the VSWR is significantly lower than that in the uncompensated and empirically compensated cases. Furthermore, except for the "double peak" phenomenon observed when the insulating dielectric diameter is 1.1 mm, the VSWR curve obtained using the compensation value of this scheme is uniformly distributed over a wide frequency range, with no second peak or a very small second peak. It maintains excellent electrical performance within the operating frequency range, verifying the effectiveness of the calculation method.

[0154] like Figure 5 As shown, Figure 5 (a) is the VSWR distribution without compensation. Figure 5 (b) Standing wave ratio distribution for empirical compensation, Figure 5 (c) Based on the compensated VSWR distribution of this application, the electrical performance under three conditions was analyzed using a projection plane. Figure 5 As can be seen from the maximum values ​​of scales (a), (b), and (c), the VSWR is highest without compensation at 1.285; with empirical compensation, it is 1.271, a reduction of only about 1%; and the compensation scheme based on this application has the lowest value at 1.190. On the other hand, although the maximum value is larger without compensation, when the radius of the insulating medium remains constant, there is generally no significant gradient in the vertical direction with frequency changes, proving that its electrical performance is uniform across a wide frequency range. While empirical compensation reduces the maximum value, there is a significant gradient in the vertical direction, meaning that when the radius of the insulating medium remains constant, its electrical performance fluctuates with frequency changes, thus the optimal performance is not universally applicable. Based on the compensation method of this scheme, when the radius of the insulating medium is in the range of 0.94–1.06 mm, the VSWR changes less with frequency and has a lower maximum value, exhibiting uniform and good electrical performance across a wide frequency range.

[0155] like Figure 6 As shown, the impedance continuity and reflection defects under the three conditions were further analyzed using TDR (Time-Domain Reflectometry) curves. Figure 6 (a) is the characteristic impedance curve of the TDR without compensation. Figure 6 (b) TDR characteristic impedance curve under empirical compensation. Figure 6 (c) shows the TDR characteristic impedance curve based on the compensation method of this application. Figure 6 (a) It is evident that the characteristic impedance is high without compensation, verifying the conclusion that the elastic slot will add parasitic inductance, indirectly indicating that the slot can be equivalent to λ. PThe short circuit within / 4. Secondly, compared to the connector impedance based on the compensation method of this application, the impedance reduction of the connector after empirical compensation is significantly higher. Therefore, its compensated distributed capacitance is excessive, which is consistent with the conclusion above that the standing wave ratio (VSWR) of empirical compensation is larger, verifying that the compensation method of this scheme is more accurate. In addition, since the size of the insulating medium needs to be further matched, the characteristic impedance consistency of the connector after compensation based on this paper will be better than that of the other two methods. Figure 6 The value of (c).

[0156] Table 2 shows the distribution of equivalent inductance, equivalent capacitance, and other parameters of the connector structure at 40GHz under three different conditions, calculated using Q3D. The data in Table 2 shows that both compensation methods reduce the equivalent inductance and increase the equivalent capacitance. However, the empirical compensation method results in a more significant reduction in equivalent inductance and increase in equivalent capacitance, leading to "overcompensation" and a substantial reduction in AC resistance. This is related to... Figure 6 (b) The empirically compensated TDR curves show a consistent large dip shape. The compensation method presented in this paper appropriately reduces the AC impedance, with a slower rate of impedance reduction.

[0157] Table 2 Overall equivalent electrical parameters under three conditions

[0158]

[0159] The calculation method described in this application can accurately predict the initial value of the inner conductor outer diameter compensation. If applied to low-frequency applications, based on the calculated values ​​of this application, the diameter of the front-end inner conductor is directly increased by 0.4 mm, and the diameter of the insulating medium is set to 0.94–1.06 mm. At this point, the maximum standing wave ratio is less than 1.15 (see...). Figure 4 (c) Figure 5 (c) This meets the usage requirements. If applied to high-performance applications, when the inner conductor diameter is increased by 0.4 mm, the required dielectric constant ε is calculated using the compensated characteristic impedance formula. total The value is 1.587, a decrease of 0.151 compared to the initial 1.738 in Table 1. The radius of the insulating medium is calculated to be 0.876 mm using the dielectric constant calculation model for composite media. Based on this, a small-range search is performed using high-frequency electrical simulation, and the results are as follows... Figure 7 As shown. According to Figure 7 It can be seen that the optimal value of the insulation dielectric compensation diameter is 0.050 mm, which is only 0.007 mm (14% deviation) from the theoretically calculated value of 0.043 mm, but has a 100% deviation from the empirical compensation value (0.100 mm); the optimal value of the insulation dielectric diameter is 0.975 mm, which covers the range of 0.94 to 1.06.

[0160] In summary, setting compensation values ​​using empirical formulas fails to achieve the intended compensation purpose and may even worsen electrical performance. Furthermore, setting initial simulation values ​​to 0.100 mm or searching around 0.100 mm based on empirical formulas significantly impacts design efficiency and accuracy. The compensation calculation method proposed in this application effectively avoids these problems.

[0161] like Figure 8 As shown, when the radius of the insulating medium is 0.0975 mm, the three-dimensional distribution of the standing wave ratio (SWR) under different compensation radii reveals that when the compensation diameter of the inner conductor is small, high-frequency reflection increases; however, when the compensation diameter of the inner conductor is large, low-frequency reflection tends to increase. When the compensation diameter of the inner conductor is 0.04–0.05 mm, i.e., the outer radius of the inner conductor is approximately 0.42 mm, the overall SWR curve distribution is the most uniform, balancing high and low frequency performance, further verifying the accuracy of the calculation method presented in this paper.

[0162] like Figure 9 As shown, (a) is a connector with an actual inner conductor outer diameter compensation value of 0.05 mm based on empirical compensation, and (b) is a connector with an actual inner conductor outer diameter compensation value of 0.025 mm based on the compensation of this application (interface insulation dielectric diameter 0.975 mm). The results were obtained using a vector network analyzer and showed standing wave ratios (SWRs) of approximately 0.05 mm. Figure 10 As shown, Figure 10 (a) Standing wave ratio under empirical compensation, Figure 10 (b) is the standing wave ratio (SWR) based on the inner conductor outer diameter compensation of this application. It can be seen that the actual test curve shape obtained based on the compensation calculation (0.025 mm) of this application is similar to... Figure 7 The simulated curves have similar shapes, with a relatively flat distribution over a wide frequency range, and a maximum value of around 1.15. In contrast, the empirical compensation clearly exhibits two peaks, similar to... Figure 8 The trend is consistent at high compensation radii, and a maximum value exceeding 1.50 is observed at high frequencies, further validating the superiority of the compensation calculation method proposed in this application. Due to the influence of other factors such as cables, welding processes, and air gaps during actual assembly, the VSWR is slightly higher than the simulated value.

[0163] Compared with existing technologies, this embodiment provides a method for compensating for impedance discontinuities in RF SMP connectors. By introducing parasitic inductance through elastic slotting, the slot width can be calculated as an equivalent short-circuit length, increasing the outer diameter of the inner conductor and maintaining the continuity of characteristic impedance, thus achieving electrical compensation. This application proposes an equivalent method based on short-circuit to obtain an approximate value of the parasitic inductance caused by slotting, and derives a convenient calculation method for the compensation diameter of the inner conductor's outer diameter through transmission parameters. This compensation diameter has a small deviation, does not introduce unnecessary capacitance parameters, and does not produce high-frequency reflection peaks. The electrical performance of the compensation design based on this application is superior to empirical compensation, and it is applicable to RF SMP connectors with different slot widths and wide frequency domains. The calculated values ​​can be directly used under low-frequency operating conditions. Under high-performance requirements, the calculation method of this scheme can effectively determine the initial simulation values, narrow the parameter search range, and improve the design efficiency and electrical performance of SMP connectors.

[0164] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0165] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for compensating impedance discontinuities in an RF SMP connector, characterized in that: Includes the following steps: The connector slot width is considered as a series of short lines of equal length connected in parallel. The parasitic inductance generated by the slot is calculated using the short-circuit load input impedance formula, which is: Where L1 is the parasitic inductance, Z0 is the characteristic impedance of the connector, and β is the phase shift constant. The width of the slot; Based on the parasitic inductance, the uncompensated distributed inductance and distributed capacitance of the connector, the slot length, the number of slots, and the characteristic impedance of the connector, the actual compensated distributed capacitance is obtained, specifically as follows: Where C0 is the uncompensated distributed capacitance, L0 is the uncompensated distributed inductance, X is the slot length, C2 is the actual compensated distributed capacitance, and N is the number of slots. The formulas for calculating the uncompensated distributed capacitance and uncompensated distributed inductance are as follows: Where ε0 is the vacuum permittivity, ε r μ is the relative permittivity of the insulating medium, μ0 is the free permeability, and μ r Let be the relative permeability of the insulating medium, D be the inner diameter of the outer conductor, and d be the outer diameter of the inner conductor without compensation; ε0 = 8.854 F / m, μ0 = 4π × 10⁻⁶. -7 N / A 2 ; Based on the distributed capacitance calculation equation and the actual compensated distributed capacitance, the inner conductor diameter compensation value is obtained as follows: Where d1 is the inner conductor diameter compensation value, and A is 5.56 × 10⁻⁶. -11 ε r ; Based on the impedance consistency principle, the equivalent dielectric constant required to achieve impedance consistency is obtained based on the connector characteristic impedance equation and the inner conductor diameter compensation value; the corrected diameter of the insulating medium is obtained based on the equivalent dielectric constant and the dielectric constant calculation model of the composite medium.

2. The method for compensating for impedance discontinuities in an RF SMP connector according to claim 1, characterized in that: The process of obtaining the equivalent dielectric constant required for impedance consistency based on the connector characteristic impedance equation and the inner conductor diameter compensation value, according to the impedance consistency principle, includes the following steps: Based on the uncompensated distributed capacitance and distributed inductance, the characteristic impedance formula is obtained: The formula for the characteristic impedance after compensation is: ； Therefore, we get: 。 3. The method for compensating for impedance discontinuities in an RF SMP connector according to claim 1, characterized in that: The corrected diameter of the insulating medium is obtained from the calculation model based on the equivalent dielectric constant and the dielectric constant of the composite medium, specifically as follows: Where, ε total ε is the equivalent dielectric constant. PTFE ε is the dielectric constant of the insulating medium. Air d is the dielectric constant of air. in The diameter is corrected for the insulating medium.

4. The method for compensating for impedance discontinuities in an RF SMP connector according to claim 1, characterized in that: The method also includes calculating the short-circuit input impedance Z using the following formula. in : ； Z in Where Ω is the short-circuit input impedance, Vp is the phase velocity (m / s), and jω is the frequency domain; The formula for calculating the phase velocity is: Where Vp is the phase velocity, ω is the real frequency, and β is the phase shift constant.

5. The method for compensating for impedance discontinuities in an RF SMP connector according to claim 1, characterized in that: The method further includes using the calculated inner conductor diameter compensation value d1 and the insulation dielectric correction diameter d in Using the initial values, a high-frequency electromagnetic field simulation is performed on the connector to conduct a small-range search, resulting in a more optimized inner conductor diameter compensation value and insulation medium correction diameter.

6. The method for compensating for impedance discontinuities in an RF SMP connector according to claim 1, characterized in that: The connector is a coaxial RF connector with a characteristic impedance of 50Ω.

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