Shielding effectiveness detection method and device for shielded room

Abstract

The present disclosure relates to a shielding effectiveness detection method for a shielded room, belonging to the field of maintenance and detection of magnetic resonance imaging devices. The method comprises: setting transmission parameters of a radio frequency signal transmitter according to detection requirements, the transmission parameters including a transmission frequency and a transmission power; transmitting, by the radio frequency signal transmitter, a radio frequency signal through a transmission antenna at a first reference position outside the shielded room; receiving, by a receiving antenna, the radio frequency signal at a second reference position outside the shielded room and separated from the first reference position by a first distance; displaying and recording, by a spectrum analyzer, a reference signal strength of the radio frequency signal; receiving, by the receiving antenna, the radio frequency signal at a plurality of test positions inside the shielded room and separated from the radio frequency signal transmitter by the first distance; obtaining and recording a plurality of test signal strengths of the received radio frequency signal; and calculating shielding effectiveness of the plurality of test positions according to the plurality of test signal strengths and the reference signal strength.

Description

Technical Field

[0001] This disclosure relates to the field of maintenance and testing of magnetic resonance imaging equipment, and more specifically, to a method and apparatus for testing the shielding effectiveness of shielded rooms. Background Technology

[0002] The shielded rooms of MRI machines may be substandard or fail to meet shielding technical requirements when newly built, or the shielding effect may be reduced due to aging and lack of maintenance in older shielded rooms. These problems can cause external radio frequency signals to leak into the shielded room, generating signal interference, resulting in severe image artifacts, affecting image quality and the accuracy of clinical diagnosis, and even leading to missed or misdiagnosis.

[0003] The methods described in this section are not necessarily methods that had been previously conceived or adopted. Unless otherwise specified, no method described in this section should be assumed to be relevant art simply because it is included in this section. Similarly, unless otherwise specified, the issues mentioned in this section should not be considered to be generally accepted in any relevant art. Summary of the Invention

[0004] In view of the above, according to the first aspect of this disclosure, a method for testing the shielding effectiveness of a shielded room is proposed, comprising: setting transmission parameters of a radio frequency signal transmitter according to testing requirements, the transmission parameters including transmission frequency and transmission power, wherein the radio frequency signal transmitter is electrically connected to a transmitting antenna; transmitting a radio frequency signal by the radio frequency signal transmitter at a first reference position outside the shielded room through the transmitting antenna; receiving the radio frequency signal by a receiving antenna at a second reference position outside the shielded room at a first distance from the first reference position, wherein the receiving antenna is electrically connected to a spectrum analyzer; obtaining and recording a reference signal strength of the received radio frequency signal; receiving the radio frequency signal at multiple test positions inside the shielded room at a first distance from the radio frequency signal transmitter outside the shielded room through the receiving antenna, wherein the shielded room is in a shielded state; obtaining and recording multiple test signal strengths of the received radio frequency signal; and calculating the shielding effectiveness of the multiple test positions based on the multiple test signal strengths and the reference signal strength.

[0005] According to a second aspect of this disclosure, a shielding effectiveness testing device for a shielded room is provided, comprising: a radio frequency signal transmitter configured to set transmission parameters of a radio frequency signal according to testing requirements, the transmission parameters including transmission frequency and transmission power; a transmitting antenna configured to be electrically connected to the radio frequency signal transmitter to transmit a radio frequency signal; a receiving antenna configured to receive the radio frequency signal transmitted by the transmitting antenna; and a spectrum analyzer configured to be electrically connected to the receiving antenna to display the waveform, receiving frequency, and signal strength of the received radio frequency signal.

[0006] According to one or more embodiments of this disclosure, by quantifying the radio frequency shielding effectiveness of the shielded room, the leakage location can be accurately located and the degree of shielding defects can be quantified in real time. This helps to communicate and coordinate with relevant parties, accelerate shielding maintenance, resolve interference artifacts as soon as possible, reduce the difficulty of on-site service, and reduce service and maintenance time. Attached Figure Description

[0007] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can more clearly understand the above and other features and advantages of the present invention, in which: Figure 1 This is a schematic flowchart of a shielding effectiveness testing method for a shielded room according to some embodiments of the present disclosure; Figure 2 This is a schematic block diagram of a shielding effectiveness testing device for a shielded room according to some embodiments of the present disclosure. Detailed Implementation

[0008] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the invention will now be described with reference to the accompanying drawings, in which the same reference numerals denote the same parts.

[0009] In this document, “illustrative” means “serving as an example, illustration or description”, and any illustration or implementation described herein as “illustrative” should not be construed as a more preferred or advantageous technical solution.

[0010] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, components with the same structure or function are shown only schematically, or only one is labeled.

[0011] In this article, "one" can mean not only "only one" but also "more than one". In this article, "first", "second", etc., are used only to distinguish one from another, not to indicate their importance, order, or mutual dependence.

[0012] The shielded rooms of MRI machines may be substandard or fail to meet shielding technical requirements when newly built, or the shielding effect may be reduced due to aging and lack of maintenance in older shielded rooms. These problems can cause external radio frequency signals to leak into the shielded room, generating signal interference, resulting in severe image artifacts, affecting image quality and the accuracy of clinical diagnosis, and even leading to missed or misdiagnosis.

[0013] Related technologies employ walkie-talkie-like transmitting and receiving equipment for testing, but this approach is limited in function, with fixed transmission frequency and power, making adjustments impossible to meet site testing requirements. Furthermore, the testing process demands a high level of expertise from the operators. This method can only roughly determine if there are problems with the shielded room as a whole; it cannot quantify the shielding effectiveness of individual locations, nor can it accurately pinpoint the specific locations of poor shielding.

[0014] This disclosure provides a method and apparatus for testing the shielding effectiveness of a shielded room. By quantitatively testing the shielding effectiveness of the shielded room, the leakage location can be accurately located and the degree of shielding defects can be quantified in real time. This helps to facilitate communication and coordination with relevant parties, accelerate shielding maintenance, resolve interference artifacts as soon as possible, reduce the difficulty of on-site service, and shorten service and maintenance time.

[0015] Exemplary embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0016] This disclosure provides a method for testing the shielding effectiveness of a shielded room. (See reference...) Figure 1 The shielding effectiveness testing method 100 for shielded rooms includes steps S102 to S114.

[0017] In step S102, the transmission parameters of the radio frequency signal transmitter can be set according to the detection requirements. The transmission parameters include the transmission frequency and the transmission power. The radio frequency signal transmitter is electrically connected to the transmission antenna.

[0018] In step S104, the radio frequency signal transmitter can transmit a radio frequency signal through a transmitting antenna at a first reference position outside the shielded room.

[0019] Step S106: The receiving antenna can receive the radio frequency signal at a second reference position outside the shielded room, which is a first distance away from the first reference position, wherein the receiving antenna is electrically connected to the spectrum analyzer.

[0020] In step S108, the reference signal strength of the received radio frequency signal can be obtained and recorded.

[0021] In step S110, radio frequency signals can be received at multiple test locations inside the shielded room and at a first distance from the radio frequency signal transmitter outside the shielded room via a receiving antenna, wherein the shielded room is in a shielded state.

[0022] Step S112 allows for the acquisition and recording of multiple test signal strengths of the received radio frequency signal.

[0023] Step S114: The shielding effectiveness of multiple test locations can be calculated based on multiple test signal strengths and reference signal strengths.

[0024] Therefore, by quantifying the radio frequency shielding effectiveness of the shielded room, the leakage location can be accurately located and the degree of shielding defects can be quantified in real time. This helps to communicate and coordinate with relevant parties, accelerate shielding repairs, resolve interference artifacts as soon as possible, reduce the difficulty of on-site services, and shorten service and repair time.

[0025] In some embodiments, the shielding room is a magnetic resonance equipment shielding room.

[0026] In step S102, the transmission parameters of the radio frequency (RF) signal transmitter can be set according to the detection requirements. These parameters include the transmission frequency and transmission power. The RF signal transmitter can be electrically connected to the transmitting antenna via a coaxial RF cable. In this example, the required RF frequency range can be determined based on the environment of the shielded room and the frequency bands of potential interference signals. For instance, if the shielded room is ineffective at shielding RF signals near the operating frequency of the magnetic resonance equipment (e.g., 64 MHz, corresponding to the hydrogen proton resonance frequency of a 1.5T magnetic resonance system), the transmission frequency of the RF signal transmitter can be set to 64 MHz. Simultaneously, based on the detection distance and ambient noise level, the transmission power can be set to -10 dBm to ensure sufficient signal strength for clear acquisition by the receiving antenna without saturating the spectrum analyzer. Furthermore, when testing broadband shielding performance, multiple frequency points can be set sequentially, such as 10 MHz, 50 MHz, 100 MHz, and 200 MHz, to evaluate the shielding effectiveness of the shielded room at different frequency bands. The transmission power can also be adjusted according to the distance of the test point; for example, it can be set to -20 dBm for close-range testing and 0 dBm for long-range testing. The frequency and power parameters set by the RF signal transmitter are stably transmitted to the transmitting antenna via a coaxial RF connection cable, and the transmitting antenna radiates RF signals of corresponding intensity and frequency outward. Through the above flexible frequency and power settings, it is possible to adapt to the needs of different types of magnetic resonance equipment, shielded rooms with different service lives, and different detection accuracies, achieving targeted quantitative testing.

[0027] In step S104, an RF signal transmitter can transmit an RF signal via a transmitting antenna at a first reference position outside the shielded room. In this example, the RF signal transmitter and transmitting antenna can be positioned in an open area outside the shielded room, away from large metal objects, other sources of RF interference, and walls that may reflect signals, to ensure the stability and repeatability of the initial reference measurement results. For example, in the shielded room testing of a 1.5 T MRI scanner, a location approximately two meters from the outer wall of the shielded room can be chosen as the first reference position, and the transmitting antenna can be mounted on a plastic tripod approximately 1.2 meters high. The RF signal transmitter is set to a transmission frequency of 64 MHz and a transmission power of -10 dBm, and then the transmitter is activated, allowing the transmitting antenna to continuously radiate an RF signal at that frequency and power.

[0028] Regardless of the site layout, it is essential to ensure that there are no obstructions between the transmitting antenna at the first reference position and the receiving antenna used for subsequent reception, and that the straight-line distance between them remains consistent with the distance measured at each test point within the shielded room. This ensures the lateral comparability of the reference signal strength S0 used in the shielding effectiveness calculation. By completing the initial setup and transmission of the transmitting signal at the first reference position, a benchmark is provided for comparing the received signal strength at each test point within the shielded room.

[0029] In step S106, a receiving antenna can receive the radio frequency (RF) signal at a second reference position outside the shielded room, at a first distance from the first reference position. The receiving antenna is electrically connected to a spectrum analyzer. In this example, after the transmitting antenna is positioned at the first reference position outside the shielded room and RF signal transmission begins, the receiving antenna and spectrum analyzer can be positioned at the second reference position outside the shielded room. A predetermined first distance is maintained between the second reference position and the first reference position. This distance is chosen to ensure that the receiving antenna can stably receive the RF signal radiated by the transmitting antenna, and that the signal strength is within the optimal detection range of the spectrum analyzer. This distance should also be strictly reproduced during subsequent measurements at various test points inside the shielded room to ensure consistency of the reference signal strength S0 used in the shielding effectiveness calculation.

[0030] In the example, during the shielded room testing of a 3.0 T MRI scanner, the transmitting antenna can be erected two meters outside the shielding room wall as the first reference position. The receiving antenna, then erected on the same straight line three meters away from the transmitting antenna, serves as the second reference position. The transmitting and receiving antennas should be in direct, unobstructed line of sight, and both should be at the same height of 1.2 meters. The transmitting frequency can be set to 128 MHz (corresponding to the hydrogen proton resonance frequency of the 3.0 T MRI system) and the transmitting power to 0 dBm in the RF transmitter. The receiving antenna is connected to the signal input of the spectrum analyzer via a coaxial RF cable. The spectrum analyzer is set to a center frequency of 128 MHz, a sweep width of 1 MHz, and an automatically adjusted reference level, matching the transmitting frequency. After transmission is initiated, the spectrum analyzer displays the waveform of the received signal in real time and reads its signal strength as -45 dBm. This value can be used as the reference signal strength S0 in subsequent shielding effectiveness calculations.

[0031] In another example, in a different testing scenario, the available space outside the shielded room is limited, making it impossible to maintain a three-meter straight-line distance between the transmitting and receiving antennas. In this case, the initial distance can be shortened to one meter, and the transmitting power can be reduced accordingly to -20 dBm to avoid the received signal being too strong and exceeding the linear detection range of the spectrum analyzer. Simultaneously, it must be ensured that the distance between the receiving and transmitting antennas remains one meter during subsequent testing inside the shielded room to guarantee comparability when calculating shielding effectiveness. In some cases, to avoid the influence of ground reflections or surrounding environmental interference on the received signal, the transmitting and receiving antennas can be simultaneously mounted on non-metallic supports at the same height, or the initial benchmark measurement can be performed in a relatively open area away from metal objects and wall reflective surfaces.

[0032] In step S108, the reference signal strength S0 of the received radio frequency signal can be obtained and recorded.

[0033] In the example, after the receiving antenna receives the radio frequency signal transmitted by the transmitting antenna at the second reference position outside the shielding room, the signal can be transmitted to the spectrum analyzer via a coaxial radio frequency connection. The spectrum analyzer processes the received signal according to preset parameters such as center frequency, sweep width, and reference level, and displays the signal's spectral distribution in real time as a waveform graph on its display screen. It also displays the current received signal strength in dBm numerical form. By observing the spectrum analyzer screen and confirming that the waveform is stable and free from abnormal fluctuations or spurious interference, the signal strength value can be read and recorded as the reference signal strength S0, serving as the benchmark value for subsequent shielding effectiveness calculations.

[0034] In step S110, radio frequency signals can be received at multiple test locations inside the shielded room and at a first distance from the radio frequency signal transmitter outside the shielded room via a receiving antenna, wherein the shielded room is in a shielded state.

[0035] It should be noted that during testing, the RF signal transmitter outside the shielded room can be located anywhere outside the shielded room. That is, it can be moved according to the test point, as long as the receiving antenna and the transmitting antenna are kept at the same distance from each other at the test location. There are no restrictions on this.

[0036] In the example, after recording the reference signal strength S0 outside the shielded room, the receiving antenna and spectrum analyzer can be moved inside the shielded room, and the shielded room door can be closed to bring the shielded room into its normal shielding state. At this time, the transmitting antenna remains outside the shielded room and continues to transmit radio frequency signals, while the receiving antenna moves inside the shielded room along a predetermined detection path to detect the radio frequency signals leaking in after passing through the shielded room shell at multiple test locations. The distance between each test location and the radio frequency signal transmitter outside the shielded room should maintain a primary distance to ensure that the signal strength S0 measured at each test point is within a certain range. nThe only difference between the reference signal strength S0 and the reference signal strength is the variable of "whether it has been attenuated by the shielding room", thus accurately calculating the shielding effectiveness at each location.

[0037] For example, during the testing of a 1.5T shielded room in use, after recording the outdoor reference signal strength S0 (-42dBm), the operator enters the shielded room with a receiving antenna and a spectrum analyzer, and closes the shielded room door. Based on the layout of the shielded room and the needs of previous troubleshooting, six test positions are pre-marked inside: the first test position is located 0.5 meters from the edge of the door, inside the door seam; the second test position is located at the center of the observation window; the third test position is located inside the ventilation waveguide window; the fourth test position is located at the corner seam; the fifth test position is located inside the equipment maintenance port; and the sixth test position is located on the ceiling directly above the magnet. At each test position, the receiving antenna can be mounted on a non-metallic bracket 1.2 meters high, maintaining a straight-line distance of three meters between the receiving antenna and the outdoor transmitting antenna (consistent with the first distance measured from the outdoor reference), while also ensuring that the pointing and polarization direction of the receiving antenna are as consistent as possible with the outdoor reference measurement.

[0038] In another example, when testing the shielding performance at the door gap of the shielded room, the receiving antenna can be placed inside the door gap, with the antenna center aligned with the gap, maintaining a distance of three meters between the receiving antenna and the outdoor transmitting antenna. After starting transmission, observe the signal strength at 64 MHz on the spectrum analyzer. If the spectrum analyzer displays a signal strength of -38 dBm, it indicates that the signal strength leaking through the door gap is even higher than the outdoor reference value (-42 dBm). The shielding effectiveness at this location is negative (-42 - (-38) = -4 dB), indicating that the signal has not been effectively attenuated but has instead experienced some coupling enhancement, suggesting a serious shielding defect at this location. The position of the receiving antenna can be further fine-tuned by moving it up and down along the door gap to find the specific point with the most severe leakage, and the signal strength at that point can be recorded.

[0039] In another example, for testing the observation window of the shielded room, the receiving antenna can be placed close to the inner glass surface of the observation window, maintaining a distance of three meters between the receiving antenna and the outdoor transmitting antenna. The signal strength displayed on the spectrum analyzer at 64 MHz is -65 dBm, and the calculated shielding effectiveness is -42 - (-65) = 23 dB, indicating that the observation window provides approximately 23 dB of attenuation for the 64 MHz RF signal. This value can be compared with the nominal shielding performance of the observation window (e.g., a factory specification greater than 60 dB) to determine whether the observation window is aging or damaged.

[0040] In another example, for shielded rooms that are large or have complex structures, operators can use a grid-based testing method for comprehensive inspection. For instance, the shielded room floor can be divided into a 1m x 1m grid, with test positions set at the intersections of each grid, and the received signal strength S read at each test position. n For inner test locations far from the outdoor transmitting antenna, such as the deepest corner of the shielded room, the transmitted signal travels a longer spatial propagation path and experiences more indoor reflections, resulting in a very weak received signal. In such cases, the reference level and resolution bandwidth of the spectrum analyzer can be adjusted appropriately to improve detection sensitivity. If the signal strength at multiple test points in a certain area is found to be abnormally high, it indicates a general problem with the corresponding shielding wall or joints in that area. If only a few points are abnormal, the specific leakage point can be precisely located, such as a cracked joint, loose screws, or poor shielding of penetrating components.

[0041] During step S110, it should be ensured that the shielded room door remains closed throughout the entire testing process to prevent additional leakage due to an unclosed door, which could affect measurement accuracy. Simultaneously, the specific coordinates of each test location and the test signal strength S can be recorded. n The waveform characteristics displayed by the spectrum analyzer should also be recorded, including any abnormal fluctuations or interference signals. By receiving RF signals at multiple test locations, the signal leakage situation inside the shielded room can be comprehensively obtained, providing a basis for subsequent calculations of the shielding effectiveness (SE) at each test point. n It provides a data foundation for locations with poor positioning and shielding.

[0042] In step S112, multiple test signal strengths S of the received radio frequency signal can be obtained and recorded. n Step S112 is similar to step S108, and will not be described in detail here.

[0043] In step S114, the shielding effectiveness of multiple test locations can be calculated based on multiple test signal strengths and reference signal strengths.

[0044] Shielding Effectiveness (SE) is defined as the difference between the strength of a reference signal and the strength of the signal at the test point, measured in decibels (dB). n = S0 - S n Where S0 is the reference signal strength recorded in step S108, S n The values ​​for the multiple test signal strengths recorded in step S112 are as follows: A higher shielding effectiveness value indicates stronger attenuation of the radio frequency signal at that location, and better shielding; conversely, a lower value, or even a negative value, indicates a shielding defect at that location and severe signal leakage. A calculator, spreadsheet software, or a pre-prepared calculation table can be used on-site to sequentially calculate the S values ​​for each test point.n Substitute into the formula to calculate the corresponding shielding effectiveness SE. n And based on the calculation results, determine whether the shielding performance of each test location meets the requirements.

[0045] In the example, during the testing of a 1.5 T shielded room, the reference signal strength S0 was recorded as -42 dBm in step S108 (transmission frequency 64 MHz, transmission power -10 dBm, and a distance of three meters between the transmitting and receiving antennas). Subsequently, in step S110, the operator measured the received signal strengths S1 to S6 at six test locations inside the shielded room and calculated the shielding effectiveness at each location in turn. The first test location was inside the door gap of the shielded room, where the measured received signal strength S1 was -38 dBm. The shielding effectiveness at this location was SE1 = S0 - S1 = (-42) - (-38) = -4 dB. The negative value indicates that this location not only failed to effectively attenuate the RF signal but also showed signal enhancement, suggesting a serious shielding leak at the door gap. This could be caused by a loose door lock, aging conductive gaskets, or poor contact with the door frame, requiring immediate repair.

[0046] The second test location was at the center inside the observation window, where the measured received signal strength S2 was -65 dBm. The shielding effectiveness at this location was SE2 = (-42) - (-65) = 23 dB. This value indicates that the observation window provides 23 dB attenuation for a 64 MHz RF signal, but this is significantly lower than the factory-specified shielding effectiveness (typically 60 dB to 80 dB). This suggests that the shielding glass or conductive coating of the observation window may have aging, scratches, or poor edge contact issues, and further inspection or replacement is recommended.

[0047] The third test location was inside the ventilated waveguide window, where the measured received signal strength S3 was -58 dBm. The shielding effectiveness at this location was SE3 = (-42) - (-58) = 16 dB. The nominal shielding effectiveness of a waveguide window is typically above 60 dB, and the actual measured value of 16 dB is far lower than the nominal value, suggesting that the waveguide window may have a blocked or damaged waveguide aperture, or be improperly installed, requiring inspection or replacement.

[0048] The fourth test location was at the corner seam, where the measured received signal strength S4 was -50 dBm. The shielding effectiveness at this location was SE4 = (-42) - (-50) = 8 dB. The low shielding effectiveness at the corner seam is usually caused by poor conductive connection between the shielding plates, insufficient overlap width, or loose bolts, requiring reinforcement of the corner seam.

[0049] The fifth test location is inside the equipment access port, where the measured received signal strength S5 is -70 dBm. The shielding effectiveness at this location is SE5 = (-42) - (-70) = 28 dB. Although 28 dB is still below the ideal value, it is slightly better than the previous locations. The decreased shielding effectiveness of the access port may be related to aging of the sealing strip or loose cover plate. It is recommended to tighten the cover plate bolts or replace the sealing strip.

[0050] The sixth test location was on the ceiling directly above the magnet, where the measured received signal strength S6 was -82 dBm. The shielding effectiveness at this location was SE6 = (-42) - (-82) = 40 dB. This was the highest shielding effectiveness among the six test points, but it was still below the standard requirements for a shielded room (generally requiring an overall shielding effectiveness greater than 80 dB). This indicates that the shielding structure in the ceiling area was relatively intact, but the overall performance of the shielded room still has room for improvement.

[0051] In some embodiments, the location of shielding leakage in the shielded room can be located by comparing the shielding effectiveness of multiple test locations.

[0052] In the example, based on the above calculations, the areas with the worst shielding performance can be quickly located. Door seams (SE = -4 dB) and wall corner seams (SE = 8 dB) are the locations with the most severe leakage and should be prioritized for maintenance. Simultaneously, these quantified test results can be provided to the user or maintenance team in report form as a basis for communication and coordination, helping all parties reach a consensus on the problems existing in the shielded room and accelerating maintenance decisions and construction progress.

[0053] In some embodiments, the transmitting antenna can be a dipole rod antenna, and the receiving antenna can be a dipole non-magnetic rod receiving antenna. The dipole rod antenna and the dipole non-magnetic rod receiving antenna are easy to assemble and disassemble, and convenient for testing.

[0054] It should be understood that the transmitting and receiving antennas can be other types of antennas, such as broadband biconical antennas, log-periodic dipole antennas, etc., and there are no restrictions here.

[0055] In some embodiments, the spectrum analyzer displays the waveform, receiving frequency, and signal strength of the received radio frequency signal in real time.

[0056] In the example, the spectrum analyzer receives the radio frequency signal from the receiving antenna via a coaxial RF connection, analyzes and processes it, and presents multi-dimensional information in a visual manner on its display screen. The waveform is presented as a curve showing the signal amplitude (vertical axis) changing with frequency (horizontal axis), forming a spectrum distribution map; the received frequency is displayed numerically at the cursor position or peak mark, in units of Hz, kHz, MHz, or GHz; the signal strength is displayed numerically at the cursor position or peak mark, in units of dBm (decibels per milliwatt), and is also visually reflected on the vertical axis scale as waveform height.

[0057] Based on the same technical concept, this application provides a shielding effectiveness testing device for shielded rooms. Embodiments of the shielding effectiveness testing device for shielded rooms can be referenced from embodiments of the shielding effectiveness testing method for shielded rooms; repeated details will not be repeated. Reference Figure 2 The shielding effectiveness testing device 200 for shielded rooms includes a radio frequency (RF) signal transmitter 210, a transmitting antenna 220, a receiving antenna 230, and a spectrum analyzer 240. The RF signal transmitter 210 is configured to set the transmission parameters of the RF signal according to the testing requirements. The transmission parameters include the transmission frequency and the transmission power. The transmitting antenna 220 is configured to be electrically connected to the RF signal transmitter to transmit the RF signal. The receiving antenna 230 is configured to receive the RF signal transmitted by the transmitting antenna. The spectrum analyzer 240 is configured to be electrically connected to the receiving antenna to display the waveform, receiving frequency, and signal strength of the received RF signal.

[0058] In some embodiments, the transmitting antenna is a dipole rod antenna and the receiving antenna is a dipole non-magnetic rod receiving antenna. The dipole rod antenna and the dipole non-magnetic rod receiving antenna are easy to assemble and disassemble, which facilitates testing. At the same time, it makes the shielding effectiveness testing device 200 for shielded rooms small, lightweight, easy to carry and set up, and low in cost.

[0059] 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., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for testing the shielding effectiveness of a shielded room, characterized in that, include: The transmission parameters of the radio frequency signal transmitter are set according to the detection requirements. The transmission parameters include the transmission frequency and the transmission power. The radio frequency signal transmitter is electrically connected to the transmission antenna. The radio frequency signal transmitter transmits a radio frequency signal through the transmitting antenna at a first reference position outside the shielding room; The radio frequency signal is received by a receiving antenna at a second reference position outside the shielding room, which is a first distance away from the first reference position, wherein the receiving antenna is electrically connected to a spectrum analyzer; Obtain and record the reference signal strength of the received radio frequency signal; The radio frequency signal is received by the receiving antenna at a plurality of test positions inside the shielded room that are separated from the radio frequency signal transmitter outside the shielded room by the first distance, wherein the shielded room is in a shielded state; Acquire and record multiple test signal strengths of the received radio frequency signal; and The shielding effectiveness of the multiple test locations is calculated based on the strength of the multiple test signals and the strength of the reference signal.

2. The method according to claim 1, characterized in that, The shielding room is the shielding room for the magnetic resonance equipment.

3. The method according to claim 1, characterized in that, The transmitting antenna is a dipole rod antenna, and the receiving antenna is a dipole non-magnetic rod receiving antenna.

4. The method according to claim 1, characterized in that, The method further includes: By comparing the shielding effectiveness at the multiple test locations, the location of shielding leakage in the shielded room can be determined.

5. The method according to any one of claims 1 to 4, characterized in that, The spectrum analyzer displays the waveform, receiving frequency, and signal strength of the received radio frequency signal in real time.

6. The method according to any one of claims 1 to 4, characterized in that, The method of setting the transmission parameters of the radio frequency signal transmitter according to the detection requirements includes: Based on the environment of the shielded room and the frequency bands of existing interference signals, the range of radio frequency frequencies to be detected is determined, and the transmission frequency is set to one or more frequency points within the range of radio frequency frequencies.

7. The method according to any one of claims 1 to 4, characterized in that, The first distance between the transmitting antenna and the receiving antenna is adjusted based on the available space outside the shielding room and the received signal strength of the receiving antenna.

8. The method according to any one of claims 1 to 4, characterized in that, The receiving of the radio frequency signals by the receiving antenna at multiple test locations within the shielded room includes: The internal space of the shielded room is divided into grids, and the test positions are set at the intersections of each grid or within each grid area. The corresponding test signal strength is read at each test position.

9. The method according to any one of claims 1 to 4, characterized in that, The shielding effectiveness is calculated using the following formula: SE n = S0-S n Among them, SE n S represents the shielding effectiveness at the nth test location, S0 represents the reference signal strength, and S... n Let be the test signal strength at the nth test location.

10. A shielding effectiveness testing device for a shielded room, characterized in that, include: A radio frequency signal transmitter is configured to set the transmission parameters of a radio frequency signal according to detection requirements, the transmission parameters including transmission frequency and transmission power; A transmitting antenna is configured to be electrically connected to the radio frequency signal transmitter to transmit the radio frequency signal; A receiving antenna is configured to receive the radio frequency signal transmitted by the transmitting antenna; and A spectrum analyzer is configured to be electrically connected to the receiving antenna to display the waveform, received frequency, and signal strength of the received radio frequency signal.

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