Capacitively enhanced reverberation chamber

Abstract

The capacitive enhanced reverberation chamber mainly comprises a shielding chamber (1), a capacitive plate (2), a stirrer (3) and an antenna (4). The shielding chamber (1) is in the shape of a cuboid, and has six walls, i.e., a front wall (11), a back wall (12), a first side wall (13), a second side wall (14), a bottom surface (15) and a top surface (16). The capacitive plate (2) is parallel to the back wall (12), and is connected with the first side wall (13), the second side wall (14), the bottom surface (15) and the top surface (16). The capacitive plate (2) is provided with a plurality of capacitors (20), which form an equivalent capacitance of the capacitive plate (2). The stirrer (3) is arranged on the back wall (12) of the shielding chamber (1). The capacitive enhanced reverberation chamber can enlarge the equivalent length of the reverberation chamber, reduce the minimum working frequency of the reverberation chamber, enlarge the equivalent stroke and effective measurement area of the stirrer, and enhance the effect of the stirrer.

Description

Technical Field

[0001] This invention relates to electromagnetic compatibility testing, and in particular to a capacitor-enhanced reverberation chamber. Background Technology

[0002] In electromagnetic compatibility (EMC) testing, the test object (Test Object) needs to be placed in a uniform electromagnetic field while the test equipment is shielded to prevent interference with the external environment. Therefore, EMC testing is typically conducted in an anechoic chamber or a reverberation chamber. Compared to the former, anechoic chambers have relatively lower testing efficiency and are mainly used for measuring large-scale devices. With the application of numerous new technologies such as 5G communication, autonomous vehicles, electronic tags, and power line carrier communication, many products require comprehensive EMC testing, making reverberation chambers often the preferred testing environment.

[0003] As an electromagnetic compatibility (EMC) measurement device, a reverberation chamber comprises a shielded chamber, an indoor stirrer, and an excitation antenna. The shielded chamber protects the test device from external interference. To achieve this shielding, the insulating material of the shielded chamber is metal. Thus, the shielded chamber, or reverberation chamber, is essentially a metallic resonant cavity. The electromagnetic field within the cavity exhibits a standing wave distribution, resulting in poor electromagnetic field uniformity. This does not meet the testing requirements for EMC radio frequency radiation immunity. Therefore, reverberation chambers typically require a stirrer to randomly "stir" the moving parts, essentially changing the position of the boundary short-circuit electric walls, thereby altering the resonant wavelength and field distribution of the resonant modes and achieving uniformity of the electromagnetic field distribution in a time-statistical average sense.

[0004] The lowest operating frequency in a current reverberation chamber depends on the resonant frequency of the resonant mode with the longest resonant wavelength in the shielded chamber, which in turn depends on the size of the shielded chamber. The larger the size, the longer the resonant wavelength and the lower the resonant frequency. Therefore, the lowest operating wavelength of a current reverberation chamber is entirely limited by the actual size of the shielded chamber.

[0005] In principle, the stirrer functions similarly to changing the position of a short-circuit electrical wall in a resonator. Therefore, the stirrer's stroke determines the range of variation in the mode resonant wavelength, the range of variation in the voltage wave nodes, and consequently, the range of the test area. Furthermore, a larger stirrer stroke results in better averaging. However, the stirrer's stroke is limited by its structural dimensions, and a larger stroke requires greater driving power. Summary of the Invention

[0006] Technical problem: The present invention proposes a capacitor-enhanced reverberation chamber, which can not only expand the equivalent stroke of the stirrer, but also expand the equivalent length of the reverberation chamber, reduce the minimum operating frequency of the reverberation chamber, and at the same time increase the available test area and enhance the effect of the stirrer.

[0007] Technical solution: The capacitor-enhanced reverberation chamber of the present invention is characterized in that the embodiment adopted by the present invention includes a shielding chamber, a capacitor plate, a stirrer, and an antenna; the interior of the shielding chamber is rectangular and has six walls: a front wall, a rear wall, a first side wall, a second side wall, a bottom surface, and a top surface; a circuit board is located inside the shielding chamber, and the capacitor plate has multiple capacitors; the stirrer is located on the rear wall of the shielding chamber; and the antenna is located inside the shielding chamber.

[0008] The capacitor plate is parallel to the rear wall, and the capacitor forms an equivalent capacitance of the capacitor plate terminated between the bottom and top surfaces.

[0009] The distance from the capacitor plate to the rear wall can be adjusted; the distance from the capacitor plate to the rear wall is less than the distance from the capacitor plate to the front wall.

[0010] The capacitor plate is parallel to the rear wall, and its shape is the same as the cross-sectional shape of the shielded chamber along the front and rear walls. The capacitor plate is electrically connected to the first side wall, the second side wall, the bottom surface, and the top surface.

[0011] The larger the equivalent capacitance of the capacitor plate, the greater its effect; the lower the operating frequency of the reverberation chamber, the higher the equivalent capacitance.

[0012] Depending on the operating frequency, capacitor plates with different equivalent capacitance values ​​can be used.

[0013] In a capacitor-enhanced reverberation chamber, the shielding chamber forms a rectangular metal resonant cavity, with the direction along the front and rear walls referred to as the longitudinal direction. In the longitudinal direction, the stirrer acts as a short circuit. When the stirrer is working, it is equivalent to the position of the rear wall changing, thus changing the equivalent distance between the front and rear walls, which in turn changes the resonant wavelength.

[0014] Along the direction of the front and rear walls, the functions of the stirrer and capacitor plate can be explained using the equivalent circuit of a transmission line. At the location of the capacitor plate, the stirrer's function is equivalent to an inductor. L According to transmission line theory, there is (1) In the above formula, ω is the operating frequency. Z It is characteristic impedance. V It is the phase velocity along the direction of the front and rear walls. A It is the distance between the stirrer and the capacitor plate. A The larger, L The larger; conversely L The larger, equivalent to A The larger the value, the greater the value. For modes with electric field components in the top and bottom directions, at the location of the capacitor plate, the equivalent capacitance of the capacitor plate is... C and L Connected in parallel, forming a total equivalent inductance. L d .

[0015] (2) set up .when hour, . The function can also be used to distance the capacitor plate. A d A short road surface equivalent. Due to ,so Therefore, the capacitor plate effectively increases the longitudinal length of the shielding chamber, thereby lowering the minimum operating frequency of the reverberation chamber.

[0016] when hour, Thus, the equivalent capacitance of the capacitor plate C and L When connected in parallel, they actually form a total equivalent capacitance, which is equivalent to the distance between the short-circuit surface and the capacitor plate being greater than one-quarter of the longitudinal wavelength.

[0017] The capacitor plate can also amplify the longitudinal travel of the stirrer. When the stirrer is working, it is equivalent to a change in the short-circuit position, which is equivalent to the stirrer's equivalent inductance at the capacitor plate position. L Changes. The greater the stroke of the agitator, the greater the range of short-circuit position variations. L The greater the range of variation, the greater the effective capacitance of the capacitor plate. C The function, Therefore, the capacitor plate is equivalent to L Amplifier of value, L Enlarged to .therefore The stroke of the equivalent mixer is greater than the stroke of the actual mixer.

[0018] Because the capacitor plate expands the longitudinal stroke of the equivalent stirrer, the field strength of the test area in the reverberation chamber is better averaged, and the longitudinal area of ​​the test area is larger.

[0019] The capacitor board is detachable, allowing it to be removed from the shielded chamber while the reverberation chamber continues to operate. Multiple capacitor board mounting positions can be located longitudinally along the front and rear walls within the shielded chamber. Alternatively, multiple capacitor boards can be placed in different locations within the shielded chamber, effectively... L In a multi-stage amplifier, the effect of the capacitor plate is more pronounced.

[0020] According to formula (2), the equivalent capacitance of the capacitor plate C The larger the value, the greater the enhancement effect of the capacitor plate.

[0021] The top and bottom surfaces of the shielded room have connecting devices, which on the one hand allow the capacitor plate to be installed inside the shielded room and ensure the electrical connection between the capacitor plate and the top and bottom surfaces, and on the other hand ensure that the capacitor plate can be disassembled and replaced.

[0022] Beneficial effects: The beneficial effects of the present invention are: the proposed capacitor-enhanced reverberation chamber expands the equivalent length of the reverberation chamber, reduces the minimum operating frequency of the reverberation chamber, and at the same time expands the equivalent stroke and effective measurement area of ​​the stirrer, thereby enhancing the effect of the stirrer. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the capacitor-enhanced reverberation chamber of the present invention; Figure 2 This is a top view of the capacitor-enhanced reverberation chamber of the present invention. Figure 3 This is a schematic diagram of the capacitor plate of the capacitor-enhanced reverberation chamber of the present invention; The diagram shows a shielded room 1, a front wall 11, a rear wall 12, a first side wall 13, a second side wall 14, a bottom surface 15, a top surface 16, a capacitor plate 2, a capacitor 20, a stirrer 3, and an antenna 4. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The specific embodiments described herein are only for explaining the present invention and should not be construed as limiting the present invention by these specific embodiments.

[0025] The implementation scheme adopted in this invention is as follows: the capacitor-enhanced reverberation chamber includes a shielding chamber 1, a capacitor plate 2, a stirrer 3, and an antenna 4; the shielding chamber 1 has a cuboid shape and has six walls: a front wall 11, a rear wall 12, a first side wall 13, a second side wall 14, a bottom surface 15, and a top surface 16; the circuit board 2 is located inside the shielding chamber 1, and the capacitor plate 2 has multiple capacitors 20; the stirrer 3 is located on the rear wall 12 of the shielding chamber 1; and the antenna 4 is located inside the shielding chamber 1.

[0026] The capacitor plate 2 is parallel to the rear wall 12, and the capacitor 20 forms an equivalent capacitor of the capacitor plate 2 with its terminals connected between the bottom surface 15 and the top surface 16.

[0027] The distance between capacitor plate 2 and rear wall 12 can be adjusted; the distance between capacitor plate 2 and rear wall 12 is less than the distance between capacitor plate 2 and front wall 11.

[0028] The capacitor plate 2 is parallel to the rear wall 12. The shape of the capacitor plate 2 is the same as the cross-sectional shape of the shielding chamber along the direction of the front wall 11 and the rear wall 12. Moreover, the capacitor plate 2 is electrically connected to the first side wall 13, the second side wall 14, the bottom surface 15 and the top surface 16.

[0029] The larger the equivalent capacitance of capacitor plate 2, the greater its effect; the lower the operating frequency of the reverberation chamber, the higher the equivalent capacitance.

[0030] Depending on the operating frequency, capacitor plates with different equivalent capacitance values ​​can be used.

[0031] In the capacitor-enhanced reverberation chamber, the shielding chamber 1 forms a cuboid metal resonant cavity. The area along the front wall 11 and the rear wall 12 is referred to as the longitudinal direction. In the longitudinal direction, the stirrer 3 acts as a short circuit. When the stirrer 3 is working, the position of the rear wall 12 is equivalent to changing, thus changing the equivalent distance between the front wall 11 and the rear wall 12, which is equivalent to changing the resonant wavelength.

[0032] Along the longitudinal direction, the functions of stirrer 3 and capacitor plate 2 can be explained using a transmission line equivalent circuit. At the location of capacitor plate 2, the function of stirrer 3 is equivalent to that of an inductor. L According to transmission line theory, there is (1) In the above formula, ω is the operating frequency. Z It is the characteristic impedance, and the phase velocity along the longitudinal direction. A It is the distance between the stirrer 3 and the capacitor plate 2. A The larger, L The larger; conversely L The larger, equivalent to A It is also larger. For a mode with an electric field component along the direction of the top surface 16 and the bottom surface 15, at the position of capacitor plate 2, the equivalent capacitance of capacitor plate 2 is... C and L Connected in parallel, forming a total equivalent inductance. L d .

[0033] (2) set up .when hour, . The function can also be achieved by using a distance of 2 from the capacitor plate. A d A short road surface equivalent. Due to ,so Therefore, capacitor plate 2 effectively increases the longitudinal length of shielding chamber 1, thereby reducing the minimum operating frequency of the reverberation chamber.

[0034] when hour, Thus, the equivalent capacitance of capacitor plate 2 C and L When connected in parallel, a total equivalent capacitance is formed. This is equivalent to the short-circuit surface being more than a quarter of the longitudinal wavelength from capacitor plate 2, and the equivalent length being greater than... The equivalent length under the given conditions.

[0035] Capacitor plate 2 can also amplify the travel of stirrer 3 along the front wall 11 and rear wall 12. When stirrer 3 is working, it is equivalent to a change in the short-circuit position, which is equivalent to the equivalent inductance of stirrer 3 at the position of capacitor plate 2. L Changes. The greater the stroke of stirrer 3, the greater the range of short-circuit position changes. L The greater the range of variation, the greater the effective capacitance of capacitor plate 2. C The function, Therefore, capacitor plate 2 is equivalent to L Amplifier of value, L Enlarged to .therefore The stroke of the equivalent mixer is greater than the stroke of the actual mixer.

[0036] The capacitor plate 2 is detachable and can be removed from the shielded chamber, at which point the reverberation chamber can still operate. Multiple capacitor plate mounting positions can be located longitudinally along the front wall 11 and rear wall 12 within the shielded chamber 1. Alternatively, multiple capacitor plates 2 can be placed in different locations within the shielded chamber 1, which is equivalent to... L In a multi-stage amplifier, the effect of capacitor plate 2 is more pronounced.

[0037] The capacitor plate 2 can be manufactured using printed circuit board technology, with multiple capacitors 20 soldered onto the substrate to form a capacitor network. The capacitors 20 are distributed throughout the capacitor plate 2 to ensure that capacitors 20 are present at locations of high electric field strength in various modes. Since the effect of the capacitor plate 2 primarily targets several modes near the lowest frequency of the reverberation chamber, the highest usable frequency of the capacitors 20 generally only needs to be greater than three times the lowest operating frequency of the reverberation chamber for the capacitor plate 2 to produce a significant effect.

[0038] Capacitor 20 can be a lumped-parameter capacitor, but when the operating frequency is high, the required equivalent capacitance value can be achieved using a distributed-parameter capacitor such as a metal gap capacitor.

[0039] The top surface 16 and bottom surface 15 of the shielding chamber 1 have connecting devices, which on the one hand allow the capacitor plate 2 to be installed inside the shielding chamber 1 and ensure that the capacitor network of the capacitor plate 2 is electrically connected to the top surface 16 and bottom surface 15, and on the other hand ensure that the capacitor plate 2 can be disassembled and replaced.

[0040] Based on the above description, the present invention can be realized.

[0041] The above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., within the design methods and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A capacitor-enhanced reverberation chamber, characterized in that... The reverberation chamber includes a shielded chamber (1), a capacitor plate (2), a stirrer (3), and an antenna (4). The shielded chamber (1) has a rectangular internal shape and six walls: a front wall (11), a rear wall (12), a first side wall (13), a second side wall (14), a bottom surface (15), and a top surface (16). The capacitor plate (2) is located inside the shielded chamber (1) and has multiple capacitors (20). The stirrer (3) is located on the rear wall (12) of the shielded chamber (1). The antenna (4) is located on the rear wall (12) of the shielded chamber (1). Inside the shielded room (1); the distance from the capacitor plate (2) to the rear wall (12) can be adjusted; the distance from the capacitor plate (2) to the rear wall (12) is less than the distance from the capacitor plate (2) to the front wall (11); the capacitor plate (2) is parallel to the rear wall (12), the shape of the capacitor plate (2) is the same as the cross-sectional shape of the shielded room along the direction of the front wall (11) and the rear wall (12), and the capacitor plate (2) is electrically connected to the first side wall (13), the second side wall (14), the bottom surface (15) and the top surface (16).

2. The capacitor-enhanced reverberation chamber according to claim 1, characterized in that... The capacitor plate (2) is parallel to the rear wall (12), and the capacitor (20) forms an equivalent capacitance of the capacitor plate (2) terminated between the bottom surface (15) and the top surface (16).

3. The capacitor-enhanced reverberation chamber according to claim 1, characterized in that... The larger the value of the equivalent capacitance of capacitor plate (2), the greater the effect of capacitor plate (2); the lower the operating frequency of the reverberation chamber, the higher the value of the equivalent capacitance.

4. The capacitor-enhanced reverberation chamber according to claim 1, characterized in that... Depending on the operating frequency, capacitor plates with different equivalent capacitance values ​​are used (2).

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