A balanced high-frequency line impedance stabilization network

Abstract

The present application relates to a balanced high-frequency line impedance stabilization network, comprising a high-frequency inductor, a radio frequency load circuit PCB, and a metal housing. The high-frequency inductor and radio frequency load circuit PCB are both located within the metal housing. The radio frequency load circuit PCB is provided with a high-frequency inductor matching network, comprising a high-frequency capacitor and a 50Ω high-frequency load resistor. The present application connects a high-frequency high-resistance inductor and a low-frequency low-resistance inductor in series in an electromagnetic compatibility radiation interference test power cable, while simultaneously connecting a 50Ω load in parallel to ground at the inductor EUT end. This creates a 50Ω radio frequency impedance as seen from the cable end under test of the balanced high-frequency line impedance stabilization network. The balanced high-frequency line impedance stabilization network generates a stable 50Ω radio frequency impedance, simulating the equivalent impedance of a power grid and providing a controlled high-frequency load impedance for the EUT AC power cable.

Description

Technical Field

[0001] The present application belongs to the technical field of electromagnetic compatibility radiation disturbance measurement, and in particular relates to a balanced high-frequency line impedance stabilization network. Background Art

[0002] The electromagnetic compatibility radiated disturbance measurement method in national standard GB / T 6113.104 is used to detect electromagnetic compatibility radiated disturbances in electronic products. During radiated disturbance measurements, a common-mode absorption device (CMAD) is used on the connecting cables that leave the test space. Because the common-mode impedance and symmetry of the cables at the point where they leave the test space (for example, at the center of the turntable) vary across different test sites, the use of a CMAD in radiated disturbance measurements is intended to reduce the variation in measurement results between different test sites. The CMAD utilizes a clamp-shaped design with a row of magnetic core material inside, through which the cable of the product under test passes. Varying cable thickness and signal frequency result in differences in the CMAD's common-mode impedance, ultimately leading to significant differences in measurement results between different test sites. Summary of the Invention

[0003] In order to solve the above-mentioned deficiencies in the prior art, a balanced high-frequency line impedance stabilization network is provided, so that the impedance of the balanced high-frequency line impedance radio frequency signal to ground is maintained at 50Ω.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] The present invention provides a balanced high-frequency line impedance stabilization network, comprising a high-frequency inductor, a radio frequency load circuit PCB, and a metal housing. The high-frequency inductor and the radio frequency load circuit PCB are both located inside the metal housing. The radio frequency load circuit PCB is provided with a high-frequency inductor matching network, which includes a high-frequency capacitor and a 50Ω high-frequency load resistor.

[0006] The metal housing includes front and rear metal panels, which are connected to the tested cable and the power supply respectively;

[0007] The backplane of the RF load circuit PCB is copper-plated over a large area, and the copper-plated portion is connected to the 50Ω high-frequency load resistor of the high-frequency inductor matching network. The copper-plated portion of the backplane of the RF load circuit PCB is connected to the metal panel through a copper plate, and the area of the copper plate is larger than the copper-plated area of the backplane of the RF load circuit PCB.

[0008] Preferably, in the balanced high-frequency line impedance stabilization network of the present invention, the high-frequency inductor is a nickel-zinc core inductor.

[0009] Preferably, in the balanced high-frequency line impedance stabilization network of the present invention, the high-frequency inductor is composed of two groups of nickel-zinc magnetic core inductors with different frequency characteristics connected in series.

[0010] Preferably, in the balanced high-frequency line impedance stabilization network of the present invention, the terminals connecting the metal panel to the tested cable and the power supply adopt banana plugs, and the radio frequency load circuit PCB board is directly fixed on the banana plugs.

[0011] Preferably, the balanced high-frequency line impedance stabilization network of the present invention further includes a calibration device, which is connected to the metal panel and is used for impedance calibration of the balanced high-frequency line impedance stabilization network, and the height of the connection position of the calibration device is consistent with the height of the connection position of the copper plate and the metal panel.

[0012] The beneficial effects of the present invention are:

[0013] By connecting a high-frequency, high-resistance inductor and a low-frequency, low-resistance inductor in series with the power cable for electromagnetic compatibility (EMC) radiated interference testing, and simultaneously connecting a 50Ω load in parallel to ground at the inductor's EUT end, a balanced high-frequency line impedance stabilization network is formed, resulting in a 50Ω RF impedance as seen from the cable end under test. Furthermore, when the RF load circuit PCB is grounded, a copper plate is used to connect the PCB backplane (with a large copper surface) to the metal panel, increasing the loop cross-sectional area and thus reducing the ground line impedance (inductive reactance).

[0014] By balancing the high-frequency line impedance stabilization network to generate a stable 50Ω RF impedance, the equivalent impedance of the power grid is simulated, providing a controlled high-frequency load impedance for the EUT AC cable. This allows the high-frequency common-mode interference signal (RF signal) on the tested cable to maintain a stable RF common-mode current under a stable resistance value, thereby improving the reproducibility and repeatability of the electromagnetic compatibility radiated interference measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The technical solution of the present application is further described below with reference to the accompanying drawings and embodiments.

[0016] Figure 1 2 is a schematic diagram of the structure of a balanced high-frequency line impedance stabilization network according to an embodiment of the present application;

[0017] Figure 2 is a circuit schematic diagram of a balanced high-frequency line impedance stabilization network according to an embodiment of the present application;

[0018] Figure 3 This is a schematic diagram of the connection between the PCB board and the copper plate of the radio frequency load circuit in the embodiment of the present application;

[0019] Figure 4 This is a schematic diagram of the connection of the calibration device in the embodiment of the present application;

[0020] The reference numerals in the figure are: 101 - tested cable end, 102 - metal panel, 103 - metal housing, 104 - RF load circuit PCB board, 105 - copper plate, 106 - 50Ω high-frequency load resistor, 107 - high-frequency inductor, 108 - banana plug, 109 - power supply end, 110 - calibration device connection position. DETAILED DESCRIPTION

[0021] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0022] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as limiting the scope of protection of this application.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0024] The technical solution of the present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0025] Example

[0026] This embodiment provides a balanced high-frequency line impedance stabilization network, such as Figure 1 As shown, the device comprises a high-frequency inductor 107, a radio frequency load circuit PCB 104, and a metal housing 103. Both the high-frequency inductor 107 and the radio frequency load circuit PCB 104 are located within the metal housing 103. A high-frequency inductor matching network is provided on the radio frequency load circuit PCB 104. The high-frequency inductor matching network comprises a high-frequency capacitor and a 50Ω high-frequency load resistor 106. This embodiment utilizes a fully metal housing to shield against external electromagnetic interference and couple to internal circuits.

[0027] The metal housing 103 includes front and rear metal panels 102, which are respectively connected to the cable under test at the cable end 101 and the power supply at the power supply end 109. The terminals connecting the metal panel 102 to the cable under test (EUT side) and the power supply (AE side) use banana plugs 108. This embodiment uses 4mm banana plugs with a sheath, which not only meets the design parameter requirements but also provides safety protection for test personnel.

[0028] The RF load circuit PCB 104 is directly attached to the metal conductor of the banana plug 108. This prevents the high-frequency inductance of the wires connecting the RF load circuit PCB 104 to the EUT / AE connection terminals on the metal panel 102 from causing the RF impedance of the balanced high-frequency line impedance stabilization network (BHIN) to be unable to maintain the RF impedance of the cable end under test 101 within the range of 50Ω±10%. Furthermore, the components of the RF load circuit PCB 104 are surface-mount devices to reduce the inductance of the device pins at high frequencies.

[0029] The back plate of the RF load circuit PCB board 104 adopts a large area copper plating design, and the copper plating part is connected to the 50Ω high-frequency load resistor 106 of the high-frequency inductor matching network on the RF load circuit PCB board 104. The copper plating part of the back plate of the RF load circuit PCB board 104 is connected to the metal panel 102 through a copper plate 105, and the area of the copper plate 105 is larger than the copper plating area of the back plate of the RF load circuit PCB board 104. The connection diagram is shown in FIG. Figure 3 .

[0030] In this embodiment, the RF load circuit PCB board 104 is grounded by using a large area of copper on the back plate, and a copper plate 105 is used to connect to the metal panel 102, which can increase the loop cross-sectional area and thus reduce the ground line impedance (inductive reactance).

[0031] In this embodiment, high-frequency inductor 107 is composed of two sets of nickel-zinc core inductors (Ln and Lc) with different frequency characteristics connected in series. One set of nickel-zinc core inductors is a high-frequency, high-resistance inductor, while the other set is a low-frequency, low-resistance inductor. High-frequency inductor 107 has an inductive reactance significantly greater than 50Ω in the 30MHz-300MHz frequency range, while its inductive reactance is significantly less than 1Ω at 50Hz (the power supply frequency).

[0032] The circuit diagram of this embodiment is as follows Figure 2 As shown, 220V AC is supplied from the power supply terminal (AE side) through the series high-frequency inductor 107 to the equipment under test (EUT). Figure 2 The medium and high frequency inductor 107 is composed of a nickel-zinc magnetic core inductor Ln and a nickel-zinc magnetic core inductor Lc connected in series.

[0033] In this embodiment, in the high-frequency inductor matching network, the high-frequency capacitor is connected in series with the 50Ω high-frequency load resistor 106. The high-frequency inductor matching network is composed of two sets of series-connected high-frequency capacitors and the 50Ω high-frequency load resistor 106. The capacitance value of the high-frequency capacitor is 1nF.

[0034] The EUT generates EMI interference signals due to its own operation, which are transmitted along the tested cable to the AE side (power supply). When viewed from the EUT port, the 50Ω high-frequency load resistor 106 and high-frequency inductor 107 on the high-frequency inductor matching network form a parallel circuit, thus achieving a high-frequency signal impedance to ground of 50Ω.

[0035] In addition, the balanced high-frequency line impedance stabilization network of this embodiment also includes a calibration device, such as Figure 4 As shown, the calibration device is connected to the metal panel 102 for impedance calibration of the balanced high-frequency line impedance stabilization network, and the height of the calibration device connection position 110 is consistent with the height of the connection position between the copper plate 105 and the metal panel 102.

[0036] Based on the above-mentioned ideal embodiments of this application, and in accordance with the above description, relevant personnel can make various changes and modifications without departing from the scope of the technical concept of this application. The technical scope of this application is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A balanced high-frequency line impedance stabilization network, comprising a high-frequency inductor, a radio frequency load circuit PCB, and a metal housing. The high-frequency inductor and the radio frequency load circuit PCB are both located within the metal housing. The radio frequency load circuit PCB is provided with a high-frequency inductor matching network. The high-frequency inductor matching network includes a high-frequency capacitor and a 50Ω high-frequency load resistor. The high-frequency capacitor and the 50Ω high-frequency load resistor are connected in series, and the 50Ω high-frequency load resistor is connected in parallel with the high-frequency inductor. The metal housing includes front and rear metal panels, which are connected to the tested cable and the power supply respectively; The backplane of the RF load circuit PCB is copper-plated over a large area, and the copper-plated portion is connected to the 50Ω high-frequency load resistor of the high-frequency inductor matching network. The copper-plated portion of the backplane of the RF load circuit PCB is connected to the metal panel through a copper plate, and the area of the copper plate is larger than the copper-plated area of the backplane of the RF load circuit PCB.

2. The balanced high-frequency line impedance stabilization network according to claim 1, characterized in that: The high frequency inductor adopts a nickel-zinc magnetic core inductor.

3. The balanced high-frequency line impedance stabilization network according to claim 2, characterized in that: The high-frequency inductor is composed of two groups of nickel-zinc magnetic core inductors with different frequency characteristics connected in series.

4. The balanced high-frequency line impedance stabilization network according to any one of claims 1 to 3, characterized in that: The terminals for connecting the metal panel with the tested cable and the power supply adopt banana plugs, and the radio frequency load circuit PCB board is directly fixed on the banana plugs.

5. The balanced high-frequency line impedance stabilization network according to claim 1, characterized in that: It also includes a calibration device, which is connected to the metal panel and is used for impedance calibration of the balanced high-frequency line impedance stabilization network. The height of the connection position of the calibration device is consistent with the height of the connection position of the copper plate and the metal panel.

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