CN212134840U

CN212134840U - Measuring device for low-frequency electromagnetic compatibility test

Info

Publication number: CN212134840U
Application number: CN202020476286.1U
Authority: CN
Inventors: 沈学其; 彭鹏; 范文远
Original assignee: Nanjing Rong Ce Detection Techniques Co ltd
Current assignee: Nanjing Rong Ce Detection Techniques Co ltd
Priority date: 2020-04-03
Filing date: 2020-04-03
Publication date: 2020-12-11
Anticipated expiration: 2030-04-03

Abstract

The measuring device for the low-frequency electromagnetic compatibility test mainly comprises a reverberation chamber (10), a stirrer (20) and three telescopic tunable linearly polarized transmitting antennas; the three antennas are connected with the three transmitters and are placed on three mutually perpendicular wall surfaces, the polarization direction of the antennas is perpendicular to the wall surfaces where the antennas are located, the antennas are located at the positions of the wall surfaces where the antennas are located and are prevented from being located at the positions of electric field zero points of modes to be excited, and a plurality of continuous modes from the lowest order to the high order are excited. The measuring device can excite the mode of the electric field in any direction, realizes the adjustment of the relative size of the excitation mode, ensures that the transmitting antenna can achieve the best matching in the whole test frequency band, has a large number of excited modes, can still improve the uniformity of the internal field intensity of the reverberation chamber when the measuring frequency is lower, such as 30MHz to 80MHz, and has high excitation efficiency.

Description

Measuring device for low-frequency electromagnetic compatibility test

Technical Field

The utility model relates to an electromagnetic compatibility test, especially, be used for measuring device of low frequency electromagnetic compatibility test.

Background

The electromagnetic compatibility test aims at verifying the sensitivity of the electrical and electronic products or systems under test (collectively referred to as test pieces) to external electromagnetic fields. In the test, the tested piece needs to be in a uniform electromagnetic field, and the test device is shielded to avoid interfering the external environment. Electromagnetic compatibility testing is usually performed in anechoic chambers or reverberant rooms, and the anechoic chambers are relatively inefficient to test. With the application of a large number of new technologies such as 5G communication, electronic tags, power line carriers and the like, a complex high-frequency radiation mode is used for many products, the electromagnetic compatibility measurement repeatability of the existing anechoic chamber is low, and the reverberation chamber becomes the preferred test environment. Currently, the reverberation room method is sequentially applied to military standard MIL-STD-461F/G, GJB151B, airborne electronic equipment standard DO-160, automobile part standard ISO 11452-11 and the like. The reverberation room method is particularly suitable for electromagnetic compatibility tests of large equipment levels, typical applications are radio frequency radiation immunity tests of whole automobiles, and the test standard SAE J551-16 of the whole automobile reverberation room method in the United states has published three versions in 2005, 2012 and 2017, but no corresponding standard exists in the international and China at present.

As one type of electromagnetic compatibility measuring device, the reverberation chamber includes a shielding chamber, a chamber stirrer, and a transmitting antenna. The shielding chamber can shield the test device from external interference. To achieve this shielding, the insulating material of the shielding chamber is metal. Thus the shielded room, i.e. the reverberation room, is equivalent to a metal waveguide resonant cavity. Because the field intensity in the cavity is in standing wave distribution during resonance, the uniformity of an electromagnetic field is poor, and the test requirement of electromagnetic compatibility radio frequency radiation immunity cannot be met, multiple resonance modes are required to be excited by a common reverberation chamber so as to ensure sufficient multimode resonance. Meanwhile, the boundary conditions are changed by adopting a mode of randomly stirring the movable parts by a stirrer, so that the field distribution of the resonance mode is changed, and the homogenization of the electromagnetic field distribution in the time statistics average sense is realized. The reverberation chamber usually uses a broadband log-periodic antenna as a transmitting antenna to transmit electromagnetic waves of a test frequency, and the desired mode is excited in the reverberation chamber. However, there are problems when the test frequency is relatively low, for example at 30MHz to 80 MHz.

A single transmit antenna has difficulties in meeting the requirements for location, polarization and scale for exciting multiple modes and can excite a smaller number of modes. If a mode is to be excited, the antenna must be in a position to produce an electric field of the same polarization as the mode field. Any mode in the reverberation chamber has a point where the electric field is zero, and if not, exactly where the antenna is located, the transmitting antenna cannot excite the mode no matter how much power is available. If the antenna is a single transmitting antenna, the excitation efficiency of a certain mode is high, and the excitation efficiency of another mode is low, even because the polarization direction of the antenna is different from the electric field direction of the excited mode, so that the mode with only the electric field of the polarization direction can not be excited at all, and the number of modes which can be excited is small. At the position of the antenna, one antenna needs to excite a plurality of different modes simultaneously, and due to the difference of the electric field distribution of the different modes, the relative size ratio of the modes in the different modes excited by a single antenna is fixed, and the ratio of the different modes probably does not meet the requirement of the test.

The antenna cannot achieve the best match over the entire test frequency band. Mismatch causes increased port reflection of the antenna and reduced excitation efficiency. The lowest working frequency of a broadband log periodic antenna used in a reverberation room is usually 80MHz, and when a test frequency is lower than the working frequency of the antenna, port reflection of the antenna increases, so that only a small part of power of a transmitter can be sent into the antenna to be radiated, excitation efficiency is low, and the power reflected by the antenna also influences the working of the transmitter. Even if a broadband log periodic antenna with a larger size is adopted, the lowest working frequency of the antenna can reach 30MHz, but because the broadband antenna with a fixed size actually has a fluctuated standing wave curve, the best matching in the whole test frequency band can not be ensured.

Therefore, the current reverberation room cannot be used for electromagnetic compatibility tests from 30MHz to 80MHz, and the application range of the reverberation room as an electromagnetic compatibility test device is limited. Because various electromagnetic environments may be encountered in the running of an automobile, the related standards specify that the frequency range of the automobile electromagnetic compatibility radio frequency radiation immunity test is 10kHz to 18GHz, wherein the test of the frequency band of 30MHz to 80MHz is a current urgent solution. Existing reverberation chamber based test devices do not meet such test requirements.

Disclosure of Invention

The utility model provides a measuring device for low frequency electromagnetic compatibility test to solve single transmitting antenna and be difficult to satisfy the problem of the requirement of excitation multiple mode to position, polarization and proportion, less, the single problem of polarization type of solving excitation mode quantity, can not reach the problem of best matching and with the problem that excitation efficiency is low in order to solve the antenna at whole test frequency channel, make when test frequency is lower, still can improve the homogeneity of reverberation room inside field intensity, improve excitation efficiency.

The technical scheme is as follows:

the utility model discloses a measuring device for low frequency electromagnetic compatibility test, its characterized in that the device includes reverberation room, agitator, three transmitting antenna; the three transmitting antennas are respectively a front wall antenna, a side wall antenna and a top surface antenna; the interior of the reverberation chamber is cuboid, and comprises six wall surfaces including a front wall, a rear wall, a first side wall, a second side wall, a bottom surface and a top surface; the stirrer is positioned on the rear wall of the reverberation chamber; the front wall antenna, the side wall antenna and the top surface antenna are all linearly polarized telescopic tuning antennas; the front wall antenna is positioned on the front wall, and the polarization direction of the front wall antenna is vertical to the front wall so as to excite a plurality of modes of an electric field with the polarization direction component of the front wall antenna; the top surface antenna is positioned on the top surface, and the polarization direction of the top surface antenna is vertical to the top surface so as to excite a plurality of modes of an electric field with components of the polarization direction of the top surface antenna; the sidewall antenna is located on the first sidewall or the second sidewall, and a polarization direction of the sidewall antenna is perpendicular to the first sidewall, so as to excite a plurality of modes of the electric field having a sidewall antenna polarization direction component.

The front wall antenna, the side wall antenna and the top surface antenna can be connected with different transmitters, and the transmitting power of each antenna can be adjusted according to specific test requirements, so that the relative sizes of different modes meet the test requirements.

And adjusting the lengths of the front wall antenna, the side wall antenna and the top surface antenna according to the test frequency band, so that the front wall antenna, the side wall antenna and the top surface antenna all reach respective optimal matching states.

The front wall antenna is arranged at the front wall, the front wall antenna is prevented from being arranged at the position of an electric field zero point of a mode to be excited, and a plurality of continuous modes from the lowest order to the high order are excited; the front wall antenna is not in the center of the front wall so as to effectively excite the even-order mode; the front wall antenna is located at a distance from the closer edge of the front wall that is between one fifth and one quarter, but not two nines and not three tenths, of the distance from the edge to its opposite edge.

The position of the top surface antenna on the top surface is to be avoided from being positioned at the zero point of an electric field of a mode to be excited, and a plurality of continuous modes from the lowest order to the high order are excited; the top surface antenna is not arranged in the center of the top surface so as to effectively excite the even-order mode; the top surface antenna is located between one fifth and one quarter, but not two nines and not three tenths, of the distance from the edge to the edge opposite the top surface.

The position of the side wall antenna on the side wall where the side wall antenna is located needs to be avoided being located at the position of an electric field zero point of a mode to be excited; the sidewall antenna is not positioned in the center of the sidewall where the sidewall antenna is positioned so as to effectively excite the even-order mode and excite a plurality of continuous modes from the lowest order to the high order; the distance of the side wall antenna from the edge near the side wall is between one fifth and one quarter of the distance from the edge to the opposite edge, but not two nineteenth times and not three tenths.

In the device, three transmitting antennas in the whole reverberation room are distributed on three mutually perpendicular wall surfaces, so that antennas with corresponding polarization exist in all three orthogonal directions. We describe the reverberation chamber in terms of a coordinate system, with the intersection of the front wall, the floor and the first side wall being the origin of the coordinate system, the direction of the x-axis pointing from the origin to the intersection of the front wall, the floor and the second side wall, the direction of the y-axis pointing from the origin to the intersection of the top wall, the front wall and the first side wall, and the direction of the z-axis pointing from the origin to the intersection of the rear wall, the first side wall and the floor. The particular location of the front wall antenna ensures that all modes with an electric field in the z-direction, p being arbitrary, m not more than 16 and n not more than 16, of the TMmnp or TEmnp modes are excited. Similarly, the specific position of the top surface antenna can ensure that all modes with arbitrary m, n not more than 16 and p not more than 16 in TMmnp or TEmnp modes with y-direction electric fields are excited; the particular location of the sidewall antenna ensures that all modes, n being arbitrary, m not greater than 16 and p not greater than 16, of the TMmnp or TEmnp modes having an electric field in the x-direction are excited. In this way more modes of all polarization directions can be excited efficiently.

The three transmitting antennas can be placed on any three mutually perpendicular walls of the reverberation room. The three transmitting antennas work simultaneously, so that not only can a mode that the electric field has only one directional component be excited, but also a mode that the electric field has two components and three components can be excited, the number of the modes in a test frequency band is greatly increased, the uniformity of the internal field intensity is greatly improved, the matching state of the transmitting antennas is improved, and the excitation efficiency is improved.

Because the input power of the three transmitting antennas can be respectively adjusted, the input power ratio of the three antennas is changed, a means for controlling the relative size of the excited mode is provided, and through simulation design, the optimized input power ratio can be found, so that the uniformity of the field intensity inside the whole reverberation chamber or the uniformity of the field intensity in the local area of the tested piece is further improved.

Because the contraction type transmitting antenna is adopted, the contraction length can be changed according to the test requirement, and the central working frequency of the antenna can be changed to be equal to the test frequency, so that the transmitting antenna can be in the optimal matching state.

The technical scheme of the measuring device for the low-frequency electromagnetic compatibility test enables the modes of the reverberation chamber to be increased and the matching of the transmitting antenna to be improved, and the result of the two combined actions enables the field intensity in the reverberation chamber to reach the field intensity which can be achieved only by thousands of watts before only by about one hundred watts of transmitting power.

Has the advantages that: the utility model has the advantages that: the measuring device for the low-frequency electromagnetic compatibility test can excite the mode of an electric field in any direction, realizes the adjustment of the relative size of the excitation mode, has the advantages that the transmitting antenna can achieve the best matching in the whole test frequency band, has a large number of excited modes, can still improve the uniformity of the field intensity inside the reverberation chamber when the measuring frequency is low, such as 30MHz to 80MHz, and has high excitation efficiency.

Drawings

Fig. 1 is a schematic diagram of a measuring device for low frequency electromagnetic compatibility testing according to the present invention;

FIG. 2 is a side view of the measuring device for low frequency electromagnetic compatibility testing of the present invention

Fig. 3 is a top view of the measuring device for low frequency electromagnetic compatibility testing of the present invention;

in the figure, there are a reverberation chamber (10), 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 stirrer (20), a front wall antenna (31), a side wall antenna (32) and a top surface antenna (33).

Detailed Description

The present invention will be further explained with reference to the drawings and examples.

The utility model discloses the embodiment that adopts is: the measuring device for the low-frequency electromagnetic compatibility test comprises a reverberation chamber 10, a stirrer 20 and three transmitting antennas; the three transmitting antennas are a front wall antenna 31, a side wall antenna 32 and a top surface antenna 33 respectively; the interior of the reverberation room 10 is cuboid, and comprises six wall surfaces including 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 agitator 20 is located on the rear wall 12 of the reverberation chamber 10; front wall antenna 31, side wall antenna 32 and top surface antenna 33 are all linearly polarized, telescopic tuned antennas; the front wall antenna 31 is located on the front wall 11, and the polarization direction of the front wall antenna 31 is perpendicular to the front wall 11, so as to excite a plurality of modes of which the electric field has a component of the polarization direction of the front wall antenna 31; top surface antenna 33 is positioned on top surface 16, with the polarization direction of top surface antenna 33 perpendicular to top surface 16, to excite multiple modes with electric fields having components of the polarization direction of top surface antenna 33; the sidewall antenna 32 is located on the first sidewall 13 or the second sidewall 14, and the polarization direction of the sidewall antenna 32 is perpendicular to the first sidewall 13, so as to excite a plurality of modes having components of the polarization direction of the sidewall antenna 32 in an electric field.

The front wall antenna 31, the side wall antenna 32 and the top surface antenna 33 can be connected with different transmitters, and the transmitting power of each antenna can be adjusted according to specific test requirements, so that the relative sizes of different modes meet the test requirements.

The lengths of the front wall antenna 31, the side wall antenna 32 and the top surface antenna 33 are adjusted according to the test frequency band, so that the front wall antenna 31, the side wall antenna 32 and the top surface antenna 33 all reach respective optimal matching states.

The front wall antenna 31 is arranged at the position of the front wall 11, and is prevented from being arranged at the position of an electric field zero point of a mode to be excited, and a plurality of continuous modes from the lowest order to the high order are excited; front wall antenna 31 is not centered on front wall 11 to effectively excite even order modes; the front wall antenna 31 is located at a distance from the closer edge of the front wall 11 that is between one fifth and one quarter, but not two nineteenth times, and not three tenths of a time the distance from that edge to its opposite edge.

The top antenna 33 is located at the top surface 16 so as not to be located at the zero point of the electric field of the mode to be excited, and excites a plurality of continuous modes starting from the lowest order to the higher order; top antenna 33 is not centered on top surface 16 to effectively excite the even order mode; the top surface antenna 33 is located between one fifth and one quarter, but not two nines and not three tenths, of the distance from the edge closer to the top surface 16 to the opposite edge.

The position of the sidewall antenna 32 on the sidewall is to be avoided from being at the zero point of the electric field of the mode to be excited; the sidewall antenna 32 is not located at the center of the sidewall where it is located, so as to effectively excite the even-order mode and excite a plurality of continuous modes from the lowest order to the higher order; the distance of the side wall antenna 32 from the edge of the side wall to which it is closer is between one fifth and one quarter, but not two nineteenth times, nor three tenths of a time, of the distance from the edge to the edge opposite it.

In the present arrangement, the three transmit antennas within the entire reverberation chamber 10 are distributed across three mutually perpendicular walls, so that there are correspondingly polarized antennas in all three orthogonal directions. We describe the reverberation chamber 10 in terms of a coordinate system, with the intersection of the front wall 11, the floor 15 and the first side wall 13 being the origin of the coordinate system, the direction of the x-axis pointing from the origin to the intersection of the front wall 11, the floor 15 and the second side wall 14, the direction of the y-axis pointing from the origin to the intersection of the top surface 16, the front wall 11 and the first side wall 13, and the direction of the z-axis pointing from the origin to the intersection of the rear wall 12, the first side wall 13 and the floor 15. The particular location of the front wall antenna 31 ensures that all modes with an electric field in the z-direction, p being arbitrary, m not more than 16 and n not more than 16, of the TMmnp or TEmnp modes are excited. Similarly, the specific location of the top antenna 33 ensures that all modes, m being arbitrary, n not greater than 16, and p not greater than 16, of TMmnp or TEmnp modes having an electric field in the y-direction are excited; the particular location of the sidewall antenna 32 ensures that all modes, n being arbitrary, m not greater than 16, and p not greater than 16, of the TMmnp or TEmnp modes having an electric field in the x-direction are excited. In this way more modes of all polarization directions can be excited efficiently.

The three transmit antennas may be placed on any three mutually perpendicular walls of the reverberation chamber 10. The three transmitting antennas work simultaneously, so that not only can a mode that the electric field has only one directional component be excited, but also a mode that the electric field has two components and three components can be excited, the number of the modes in the test frequency band is greatly increased, the uniformity of the field intensity in the reverberation chamber 10 is greatly improved, the matching state of the transmitting antennas is improved, and the excitation efficiency is improved.

Because the input power of the three transmitting antennas can be respectively adjusted, the input power ratio of the three antennas is changed, a means for controlling the relative size of the excited mode is provided, and through simulation design, the optimized input power ratio can be found, so as to further improve the uniformity of the field intensity in the whole reverberation chamber 10 or the uniformity of the field intensity in the local area of the tested piece.

The technical scheme of the measuring device for the low-frequency electromagnetic compatibility test enables the modes of the reverberation chamber to be increased and the matching of the transmitting antenna to be improved, and the result of the two combined actions enables the field intensity in the reverberation chamber to reach the field intensity which can be achieved by thousands of watts before only by about one hundred watts of transmitting power, so that the test requirement is met.

According to the above, alright realize the utility model discloses.

Claims

1. Measuring device for low-frequency electromagnetic compatibility tests, characterized in that it comprises a reverberation chamber (10), a stirrer (20), three transmitting antennas; the three transmitting antennas are respectively a front wall antenna (31), a side wall antenna (32) and a top surface antenna (33); the interior of the reverberation chamber (10) is a cuboid, and comprises six wall surfaces including 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 stirrer (20) is positioned on the rear wall (12) of the reverberation chamber (10); the front wall antenna (31), the side wall antenna (32) and the top surface antenna (33) are all linearly polarized telescopic tuning antennas; the front wall antenna (31) is positioned on the front wall (11), and the polarization direction of the front wall antenna (31) is vertical to the front wall (11) so as to excite a plurality of modes of an electric field with the polarization direction component of the front wall antenna (31); the top surface antenna (33) is positioned on the top surface (16), and the polarization direction of the top surface antenna (33) is vertical to the top surface (16) so as to excite a plurality of modes of an electric field with the polarization direction component of the top surface antenna (33); the sidewall antenna (32) is located on the first sidewall (13) or the second sidewall (14), and a polarization direction of the sidewall antenna (32) is perpendicular to the first sidewall (13) to excite a plurality of modes in which an electric field has a component of the polarization direction of the sidewall antenna (32).

2. The measuring device for low frequency electromagnetic compatibility testing according to claim 1, characterized in that the front wall antenna (31), the side wall antenna (32) and the top surface antenna (33) can be connected to different transmitters, and the transmission power of each antenna can be adjusted according to specific testing requirements, so that the relative sizes of the different modes meet the testing requirements.

3. The measuring device for the low frequency electromagnetic compatibility test according to claim 1, characterized in that the lengths of the front wall antenna (31), the side wall antenna (32) and the top surface antenna (33) are adjusted according to the test frequency band, so that the front wall antenna (31), the side wall antenna (32) and the top surface antenna (33) all reach respective optimal matching states.

4. Measuring device for low-frequency emc tests according to claim 1, characterized in that the front-wall antenna (31) is at the position of the front wall (11) to avoid being at the position of the electric field zero of the mode to be excited and to excite a succession of modes starting from the lowest order and going to the higher order; the front wall antenna (31) is not arranged in the center of the front wall (11) so as to effectively excite the even-order mode; the front wall antenna (31) is located at a distance from the closer edge of the front wall (11) of between one fifth and one quarter, but not two nines and not three tenths, of the distance from the edge to its opposite edge.

5. A measuring device for low-frequency emc test according to claim 1, characterized in that the top antenna (33) is located at the top surface (16) so as to avoid being located at the electric field zero point of the mode to be excited and to excite a plurality of modes in succession starting from the lowest order and going to the higher order; the top surface antenna (33) is not arranged at the center of the top surface (16) so as to effectively excite even-order mode; the top surface antenna (33) is located between one fifth and one quarter, but not two nines and not three tenths, of the distance from the edge to the edge opposite the top surface (16) closer to the edge.

6. The measuring device for low-frequency electromagnetic compatibility testing according to claim 1, characterized in that the sidewall antenna (32) is at the position of its sidewall, to avoid being at the position of the zero point of the electric field of the mode to be excited; the sidewall antenna (32) is not positioned in the center of the sidewall where the sidewall antenna is positioned so as to effectively excite the even-order mode and excite a plurality of continuous modes from the lowest order to the high order; the distance of the side wall antenna (32) from the edge of the side wall to which it is closer is between one fifth and one quarter, but not two nines and not three tenths, of the distance from the edge to the edge opposite it.