Method for analyzing and designing shielding characteristics of slotted shielding cavity

Abstract

The invention relates to the field of electromagnetic compatibility design, in particular to a slotted shielding cavity shielding characteristic analysis and design method, which comprises the following steps of: determining a slot long edge and a slot short edge according to a slot structure on the surface of a slotted shielding cavity; according to a rectangular waveguide theory, a slot on the surface of the slotted shielding cavity is equivalent to a rectangular waveguide, a plane wave is used as an external interference source, the polarization direction of the plane wave is respectively perpendicular to the long edge of the slot, the shielding effectiveness of the slotted cavity is calculated through simulation software, and a characteristic analysis result of the slotted cavity is obtained through comparative analysis; and designing the slit structure of the slit case according to the characteristic analysis result of the slit cavity, and optimizing the shielding effectiveness of the slit case. According to the invention, the shielding characteristics of plane waves entering the slotted shielding case can be analyzed through the rectangular waveguide theory, and the slots of the slot-counting shielding cavity are designed according to the main propagation mode of external electromagnetic waves and the coupling mechanism of the slots and the electromagnetic waves, so that the shielding effectiveness of the slot-counting shielding cavity is optimal.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic compatibility design, and particularly relates to an analysis and design method for the shielding characteristics of a slotted shielding cavity. Background Art

[0002] During the operation of electronic devices, they often generate external radiation and are easily affected by external electromagnetic waves. Therefore, a shielding enclosure is generally added to the electronic devices. At the same time, heat is generated during the operation of the electronic devices, and generally there are heat dissipation holes and slits. In addition, the shielding enclosure of the electronic device is not a whole, but is composed of upper and lower plates bound together, and there will also be contact gaps between the screws. In this way, external electromagnetic waves easily enter the shielding cavity through the gaps of the shielding chassis, thereby affecting the internal electronic devices, and the electromagnetic interference of the internal devices will also leak out through the gaps. Therefore, when designing the shielding chassis, how to analyze and design the shielding ability of the cavity with slits is crucial.

[0003] Shielding effectiveness refers to the ability of a shielding material or structure to suppress the electromagnetic field, and is used to measure its shielding effect on electromagnetic radiation. It reflects the attenuation degree of the shielding material or structure to electromagnetic waves within a certain frequency range, and the shielding effectiveness is usually expressed in decibels (dB).

[0004] At present, some existing technologies have obtained the influence laws of the structural parameters of the cavity, slits, and hole arrays on the electromagnetic resonance characteristics of electronic products through simulation analysis. They mainly use simulation analysis to study the influence laws of the slit structure, cavity shape, hole arrays, etc. on the electromagnetic resonance characteristics of electronic products, but do not use the waveguide principle to equivalent the slits to waveguides to analyze the influence on the shielding performance of the slotted chassis. The shape and size of the slits have different coupling effects with external electromagnetic waves, and a method that combines the coupling effect of the slits and electromagnetic waves to design the structure of the slotted chassis, which can optimize the shielding characteristics of the slotted chassis, is needed. Summary of the Invention

[0005] To solve the technical problems existing in the prior art, the present invention provides an analysis and design method for the shielding effectiveness of a slotted shielding cavity, which can analyze the shielding characteristics of a plane wave entering a slotted shielding chassis through the rectangular waveguide theory, and design the slits of the slotted shielding cavity according to the main propagation mode of external electromagnetic waves and the coupling mechanism between the slits and electromagnetic waves, so as to optimize the shielding effectiveness of the slotted shielding cavity.

[0006] The present invention can be achieved by adopting the following technical solutions:

[0007] An analysis and design method for the shielding effectiveness of a slotted shielding cavity, the method comprising:

[0008] S1. Determine the long side and short side of the gap according to the gap structure on the surface of the slotted shielding cavity;

[0009] S2. According to the rectangular waveguide theory, the gap on the surface of the slotted shielding cavity is equivalent to a rectangular waveguide. Using a plane wave as an external interference source, when the polarization direction of the plane wave is perpendicular to the long side of the gap respectively, calculate the three-dimensional electromagnetic field distribution of the TE 10 wave in the equivalent waveguide of the gap, and calculate the cut-off frequency of the TE 10 wave; When the plane wave is incident on the slotted cavity parallel to the long side of the gap, calculate the three-dimensional electromagnetic field distribution of the TE01 wave in the equivalent waveguide of the gap, and calculate the TE 10 wave cut-off frequency;

[0010] S3. Compare and analyze the three-dimensional electromagnetic field distribution and cut-off frequency of the TE10 wave in the equivalent waveguide of the gap and the three-dimensional electromagnetic field distribution and cut-off frequency of the TE01 wave in the equivalent waveguide of the gap, and obtain the analysis result of the characteristics of the slotted cavity: When the plane wave polarization direction is parallel to the long side of the gap and incident on the slotted cavity, the calculated shielding effectiveness of the slotted cavity is greater than that when the plane wave polarization direction is perpendicular to the long side of the gap and incident on the slotted cavity;

[0011] S4. Design the gap structure of the slotted chassis according to the analysis result of the characteristics of the slotted cavity, and optimize the shielding characteristics of the slotted chassis.

[0012] Specifically, the step S2 includes:

[0013] Calculate the three-dimensional electromagnetic field distribution of the TE 10 wave in the equivalent waveguide of the gap. Substitute m = 1 and n = 0 into the rectangular waveguide transmission equation, and calculate the field distribution of the TE 10 wave;

[0014] Calculate the cut-off frequency of the TE 10 wave. The expression for the cut-off frequency of the TE 10 wave is:

[0015]

[0016] where μ is the magnetic permeability, ε is the permittivity, a is the length of the long side of the gap, and b is the length of the short side of the gap;

[0017] Calculate the three-dimensional electromagnetic field distribution of the TE01 wave in the equivalent waveguide of the gap. Substitute m = 0 and n = 1 into the rectangular waveguide equation, and calculate the field distribution of the TE01 wave;

[0018] Calculate the cut-off frequency of the TE 01 wave. The cut-off frequency of the TE 01 wave is:

[0019]

[0020] Among them, b is the length of the short side of the gap, and w c What does it represent?

[0021] Specifically, the field distribution of the TE 10 wave is expressed as:

[0022]

[0023]

[0024]

[0025] E x (x, y) = H y (x, y) = E z (x, y) = 0

[0026] Among them, x, y, and z represent the three-dimensional coordinate values of the electromagnetic wave propagation. H z , H x respectively represent the magnetic field components in the z and x propagation directions of the electromagnetic wave, and E y , E x respectively represent the electric components in the z and x propagation directions of the electromagnetic wave. β is the propagation constant, and a is the length of the long side of the gap.

[0027] Specifically, the field distribution of the TE01 wave is:

[0028]

[0029]

[0030]

[0031] E y (x, y) = H x (x, y) = E z (x, y) = 0

[0032] Specifically, step S5 includes: when the external electromagnetic wave is mainly horizontally polarized, the gap of the slotted shielding cavity is set in the horizontal direction; when the external electromagnetic wave is mainly vertically polarized, the gap of the slotted shielding cavity is set in the vertical direction.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] The present invention provides an analysis and design method for a slotted shielding cavity. According to the two main transmission modes of a rectangular waveguide, the slot is equivalent to a rectangular waveguide, and the shielding characteristics of a plane wave entering a slotted shielding enclosure can be analyzed through rectangular waveguide theory. Based on the main propagation mode of external electromagnetic waves and the coupling mechanism between the slot and the electromagnetic wave, the slot of the slotted shielding cavity is designed to optimize the shielding effectiveness of the slotted shielding cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0036] Figure 1 is a flowchart of the analysis and design method for analyzing the shielding effectiveness of a slotted cavity in an embodiment of the present invention;

[0037] Figure 2 is a schematic diagram of a slotted shielding cavity in an embodiment of the present invention;

[0038] Figure 3 is a schematic diagram of a rectangular waveguide in an embodiment of the present invention;

[0039] Figure 4 is TE in an embodiment of the present invention 10 three-dimensional electromagnetic field distribution diagram;

[0040] Figure 5 is TE in an embodiment of the present invention 01 three-dimensional electromagnetic field distribution diagram;

[0041] Figure 6 is a schematic diagram of a plane wave in an embodiment of the present invention;

[0042] Figure 7 is a schematic diagram of the simulation results of the shielding effectiveness of perpendicular incidence of different polarization directions on a slotted enclosure in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The following will further describe the technical solutions of the present invention in detail in conjunction with the drawings and embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. The embodiments of the present invention are not limited thereto. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0044] Embodiment 1:

[0045] Electronic devices are prone to generating radiation and are also sensitive components. Generally, a shielding housing is added to the electronic device. When the electronic device is working, it generates heat and makes connections with the outside world. Usually, the shielding cavity is not a completely enclosed shielding housing and has holes and slots. In this way, external electromagnetic waves can enter the shielding housing through the holes and slots and then enter the interior of the chassis, and the electromagnetic radiation generated by the electronic device will also leak out through the holes and slots. Therefore, it is crucial to design the shielding characteristics of the chassis at the initial stage of the design of the slotted chassis. The present invention equates the slot to a rectangular waveguide and uses the rectangular waveguide theory to analyze the shielding characteristics of the slotted shielding chassis, so as to evaluate and judge the electromagnetic shielding performance of the slotted cavity at the initial stage of the design and provide assistance for the electromagnetic compatibility design of the product.

[0046] In the present invention, first, the slot structure is determined on the outer surface of the slotted cavity to determine the long side, the short side and the slot direction. The present invention does not limit on which surface of the shielding chassis the slot is located. Then, the rectangular waveguide theory is analyzed. According to the two main transmission modes of the rectangular waveguide, finally, the slot is equated to a rectangular waveguide, and the rectangular waveguide theory is used to analyze the shielding characteristics of the plane wave entering the slotted shielding chassis. According to the main propagation mode of the external electromagnetic wave and the coupling mechanism between the slot and the electromagnetic wave, the shielding design of the slotted chassis is carried out to make its shielding ability reach the optimal.

[0047] As Figure 1 shown, an analysis and design method for the shielding effectiveness of a slotted shielding cavity according to the present invention includes the following steps:

[0048] S1. Determine the long side and the short side of the slot according to the geometric structure of the slot on the surface of the slotted shielding cavity.

[0049] As Figure 2 shown, a schematic diagram of a slotted shielding cavity. The front surface of the shielding cavity has a slot 1. It is not limited on which surface of the cavity the slot is located and how many slots there are. The length of the long side of the slot is a, the length of the short side is b, and the slot direction is parallel to the horizontal plane.

[0050] S2. According to the rectangular waveguide theory, equate the slot on the surface of the slotted shielding cavity to a rectangular waveguide. Use the plane wave as the external interference source. Respectively make the polarization direction of the plane wave perpendicular to the long side of the slot, calculate the three-dimensional electromagnetic field distribution of the TE 10 wave in the equivalent waveguide of the slot, and calculate the cut-off frequency of the TE 10 wave; Make the plane wave incident on the slotted cavity parallel to the long side of the slot, calculate the three-dimensional electromagnetic field distribution of the TE 01 wave in the equivalent waveguide of the slot, and calculate the cut-off frequency of the TE 10 wave.

[0051] As Figure 3As shown, the schematic diagram of a rectangular waveguide. A rectangular waveguide is a commonly used broadband transmission and wave - guiding structure for the propagation of electromagnetic waves, especially suitable for the microwave and millimeter - wave frequency bands. It is usually made of metal, has a rectangular cross - section, and the internal space is used for transmitting electromagnetic waves. The rectangular waveguide consists of four boundaries, namely two parallel long sides and two parallel short sides. A typical rectangular waveguide cross - section can be square or rectangular, and the length of the long side is usually greater than the wavelength. The rectangular waveguide guides waves through internal reflection and diffraction, enabling electromagnetic waves to propagate along the inside of the waveguide. Electromagnetic waves satisfy specific boundary conditions on the conductor boundaries, resulting in the propagation and resonance of multiple propagation modes. The multiple propagation modes include the fundamental mode (TE 10 ) and many higher - order modes TE mn . The selection of the mode depends on the size of the waveguide and the operating frequency. Among them, for TE mn , m and n have different values. Each combination of m and n corresponds to a possible propagation mode. m and n can be 0, but they cannot be 0 at the same time.

[0052] In this embodiment, taking the two main transmission modes of the rectangular waveguide: TE 10 and TE 01 as examples, when m = 1 and n = 0, TE mn is TE 10 . When m = 0 and n = 1, TE mn is TE 01 . When a plane wave with its polarization direction perpendicular to the long side of the slot is incident perpendicularly on the slotted cavity, after the plane wave enters the slot, it mainly enters the cavity in the form of TE 10 wave. And when the plane wave polarization direction is incident perpendicularly on the slotted cavity, after the plane wave enters the slot, it mainly enters the cavity in the form of TE 01 wave.

[0053] Calculate the three - dimensional electromagnetic field distribution of the equivalent form waveguide of the TE 10 wave and TE 01 wave in the slot.

[0054] In the transverse electric wave TE wave, the electric field component E z = 0, and the magnetic field component H z ≠ 0. Therefore, the electric lines of force only exist in the cross - section perpendicular to the propagation direction, and the magnetic field has a component H z in the propagation direction. The TE 10 wave has the lowest cut - off frequency among all the modes in the rectangular waveguide. Therefore, the TE 10 wave is also called the main mode of the rectangular waveguide.

[0055] Calculate TE 10The three-dimensional electromagnetic field distribution of the equivalent form waveguide of the wave in the slot. Substituting m = 1 and n = 0 into the rectangular waveguide transmission equation, the field distribution of the TE 10 wave is calculated as follows:

[0056]

[0057]

[0058]

[0059] E x (x, y) = H y (x, y) = E z (x, y) = 0 (2 - 4)

[0060] where x, y, and z represent the three-dimensional coordinate values of the electromagnetic wave propagation. H z and H x represent the magnetic field components in the z and x propagation directions of the electromagnetic wave respectively. E y and E x represent the electric field components in the z and x propagation directions of the electromagnetic wave respectively. β is the propagation constant, and a is the length of the long side of the slot;

[0061] The instantaneous value expression of the field distribution of the TE 10 wave is:

[0062]

[0063]

[0064]

[0065] E x (x, y, z, t) = H y (x, y, z, t) = E z (x, y, z, t) = 0 (2 - 8)

[0066] where w represents the angular frequency and t represents time;

[0067] The TE 10 wave does not have E x , H y , E z components. And the variation of the three components E y , H x , E x has nothing to do with the vertical coordinate y. Therefore, all components of the TE 10 wave in the waveguide have nothing to do with the variation of y. From Equation (2 - 2), it can be seen that the E y component changes in a sine form along the x direction. At x = 0 and x = a, E y= 0. At the center of the long side x = a / 2, E y reaches its maximum value. Therefore, there is a half-standing wave distribution of the electric field along the long side a. And in the propagation direction +z, the amplitude of the electric field E y varies sinusoidally with the propagation distance along the +z direction.

[0068] TE 10 has a different magnetic field distribution from the electric field distribution. The TE 10 magnetic field has two components, namely H x and H z . According to Equation (2-3), it can be found that H x varies sinusoidally in the x direction. At x = 0 and x = a, H x is 0. At x = a / 2, H x reaches its maximum value, that is, there is a half-standing wave on the long side a. According to Equation (2-1), it can be found that H z has a cosine distribution in the x direction. It is 0 at x = a / 2 and reaches its maximum at both ends. By comparing Equation (2-1) with Equation (2-3), it is found that H z and H x are out of phase by 90 degrees, and their superposition makes the magnetic field finally form an elliptical shape inside the rectangular waveguide.

[0069] Combining the electromagnetic distribution of the TE 10 wave inside the waveguide, the spatial distribution of the electromagnetic force lines inside the rectangular waveguide is obtained, as shown in Figure 4 the three-dimensional electromagnetic field distribution diagram of the TE 10 wave.

[0070] Calculate the cut-off frequency of the TE 10 wave. The expression for the cut-off frequency of the TE wave is:

[0071]

[0072] where m and n have different values, and each combination of m and n corresponds to a possible propagation mode; μ is the magnetic permeability, and ε is the permittivity.

[0073] Substitute m = 1 and n = 0 into the cut-off frequency expression, and the calculated cut-off frequency of the TE 10 wave is

[0074]

[0075] Calculate the three-dimensional electromagnetic field distribution of the equivalent waveguide of the TE 01 wave in the slot. Substitute m = 0 and n = 1 into the rectangular waveguide equation, and the field equation of the TE 01 wave is obtained:

[0076]

[0077]

[0078]

[0079] E y (x, y) = H x (x, y) = E z (x, y) = 0(2 - 13)

[0080] Among them, b is the length of the short side of the gap;

[0081] TE 01 The instantaneous value expression of the field distribution of the wave is:

[0082]

[0083]

[0084]

[0085] E y (x, y, z, t) = H x (x, y) = E z (x, y) = 0(2 - 17)

[0086] TE 01 The three-dimensional electromagnetic field distribution diagram of the wave is as Figure 5 shown.

[0087] TE 01 is very similar to the TE 10 structural diagram. TE 01 is equivalent to rotating the TE 10 as a whole by 90 degrees. TE 01 The electric field direction of the wave has only two directions, namely the positive x direction and the negative x direction. In the propagation direction z, the electric field direction alternates between the positive x direction and the negative x direction in the form of a trigonometric function transformation. The electric field has a half-standing wave distribution along the short side direction (i.e., the y direction) at the port, and the cut-off wavelength is 2b. The magnetic field has no x component, and H y and H x superposition makes the magnetic field form an elliptical distribution in the yoz plane

[0088] Calculate the cut-off frequency of the TE 01 wave. Substitute m = 1 and n = 0 into the expression 2 - 8, and the cut-off frequency of the TE 01 wave can be obtained as:

[0089]

[0090] Among them, b is the length of the short side of the gap, w cis the cut-off angular frequency.

[0091] As Figure 6 shown, the schematic diagram of the plane wave, and the cavity with a slit is as Figure 2 shown. The cavity size is 50mm * 20mm * 30mm, and the slit size is 25mm * 0.5mm. When the direction of the plane wave electric field E is perpendicular to the ground, it is a vertically polarized wave; when the electric field is parallel to the ground, it is a horizontally polarized wave.

[0092] S3. Compare and analyze the three-dimensional electromagnetic field distribution and cut-off frequency of the equivalent waveguide of the TE10 wave in the slit and the three-dimensional electromagnetic field distribution and cut-off frequency of the equivalent waveguide of the TE01 wave in the slit, and obtain the analysis results of the characteristics of the cavity with a slit: when the polarization direction of the plane wave is parallel to the long side of the slit and incident on the cavity with a slit, the calculated shielding effectiveness of the cavity with a slit is greater than that when the polarization direction of the plane wave is perpendicular to the long side of the slit and incident on the cavity with a slit.

[0093] Compare and analyze the shielding effectiveness of the cavity with a slit calculated when the plane wave is perpendicular to the long side of the slit and incident on the cavity with a slit and the shielding effectiveness of the cavity with a slit calculated when the plane wave is parallel to the long side of the slit and incident on the cavity with a slit, and obtain the analysis results of the characteristics of the cavity with a slit:

[0094] Specifically, when the vertically polarized wave (i.e., the direction of the electric field is perpendicular to the long side of the slit) is perpendicularly incident on the cavity with a slit, after the plane wave enters the slit, it mainly enters the cavity in the form of the TE 10 wave. When the horizontally polarized wave (i.e., the direction of the electric field is parallel to the long side of the slit) is perpendicularly incident on the cavity with a slit, after the plane wave enters the slit, it mainly enters the cavity in the form of the TE 01 wave. The cut-off frequency of the TE 10 wave is much lower than that of the TE 01 wave. Therefore, when the horizontally polarized electromagnetic wave (i.e., the direction of the electric field is parallel to the long side of the slit) is incident on the cavity with a slit, the shielding characteristics of the cavity are much higher than those of the vertically polarized (i.e., the direction of the electric field is perpendicular to the long side of the slit) plane wave perpendicularly incident on the cavity with a slit.

[0095] As Figure 7 shown, the schematic diagram of the simulation results of the shielding effectiveness of the cavity with a slit perpendicularly incident with different polarization directions. The present invention uses the CST simulation software for simulation and verification. It can be seen from the simulation results that the shielding effectiveness of the horizontally polarized (i.e., the direction of the electric field is parallel to the long side of the slit) plane wave incident on the cavity with a slit is much greater than that of the horizontally polarized plane wave incident on the cavity with a slit, with an overall difference of more than 60 dB. This is because the direction of the electric field of the horizontally polarized plane wave is parallel to the long side of the slit. After entering the slit, the propagation mode at the slit is the TE 01 wave, while the direction of the electric field of the vertically polarized plane wave is perpendicular to the long side of the slit. After entering the slit, the propagation mode is the TE 10For the wave, through analysis, it can be known that when a vertically polarized plane wave is vertically incident on the shielding chassis, the cut-off frequency is much lower than that when a horizontally polarized plane wave is vertically incident on the shielding chassis. Therefore, the vertically polarized plane wave is more likely to enter the shielding chassis, and the shielding effectiveness of the slotted chassis is reduced compared with the case of vertically incident horizontally polarized electromagnetic waves.

[0096] S5. Design the slot structure of the slotted chassis according to the analysis results of the characteristics of the slotted cavity to optimize the shielding characteristics of the slotted chassis.

[0097] Specifically, when the external electromagnetic wave is mainly horizontally polarized (the electric field is along the x direction), the slots of the slotted chassis are set in the horizontal direction, which has little impact on the shielding effectiveness while increasing the ventilation and heat dissipation of the shielding chassis. When the external electromagnetic wave is mainly vertically polarized (the electric field is along the y direction), the slots of the slotted chassis can be set in the vertical direction, which has little impact on the shielding effectiveness while increasing the ventilation and heat dissipation of the shielding chassis.

[0098] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for analyzing and designing the shielding characteristics of a slotted shielding cavity, characterized in that, It includes the following steps: S1. Determine the long side and short side of the gap according to the gap structure on the surface of the slotted shielding cavity; S2. According to the rectangular waveguide theory, the slots on the surface of the slotted shielding cavity are equivalent to rectangular waveguides. Using a plane wave as an external interference source, when the polarization direction of the plane wave is perpendicular to the long side of the slot respectively, calculate the three-dimensional electromagnetic field distribution of the TE10 wave in the equivalent rectangular waveguide of the slot, and calculate the cut-off frequency of the TE 10 wave; When the plane wave is incident on the slotted cavity parallel to the long side of the slot, calculate the three-dimensional electromagnetic field distribution of the TE01 wave in the equivalent rectangular waveguide of the slot, and calculate the cut-off frequency of the TE 10 wave; S3. Compare and analyze the three-dimensional electromagnetic field distribution and cut-off frequency of the equivalent waveguide of the TE10 wave in the gap and the three-dimensional electromagnetic field distribution and cut-off frequency of the equivalent waveguide of the TE01 wave in the gap to obtain the analysis results of the characteristics of the slotted cavity: when the polarization direction of the plane wave is parallel to the long side of the gap and incident on the slotted cavity, the calculated shielding effectiveness of the slotted cavity is greater than that when the polarization direction of the plane wave is perpendicular to the long side of the gap and incident on the slotted cavity; S4. Design the gap structure of the slotted chassis according to the analysis results of the characteristics of the slotted cavity to optimize the shielding characteristics of the slotted chassis.

2. The method for analyzing and designing the shielding characteristics of a slotted shielding cavity according to claim 1, characterized in that, The step S2 includes: Calculating TE 10 For the three-dimensional electromagnetic field distribution of the equivalent form waveguide of the wave in the slot, substitute m = 1 and n = 0 into the rectangular waveguide transmission equation, and calculate to obtain the field distribution of the TE 10 wave; Calculating the cut-off frequency of the TE wave 10 The cut-off frequency of the TE wave 10 The expression for the cut-off frequency of the TE wave is as follows: where μ is the magnetic permeability, ε is the permittivity, a is the length of the long side of the gap, and b is the length of the short side of the gap; Calculate the three-dimensional electromagnetic field distribution of the equivalent form waveguide of the TE01 wave in the slot. Substitute m = 0 and n = 1 into the rectangular waveguide equation to calculate the field distribution of the TE 01 wave; Calculate the cut-off frequency of the TE 01 wave, the cut-off frequency of the TE 01 wave is as follows: where b is the length of the short side of the gap and wc is the cut-off angular frequency.

3. The method for analyzing and designing the shielding characteristics of a slotted shielding cavity according to claim 2, characterized in that, The TE 10 field distribution of the wave is expressed as: E x (x, y, z, t) = H y (x, y, z, t) = E z (x, y, z, t) = 0; where x, y, and z represent the three-dimensional coordinate values of the electromagnetic wave propagation, and H z and H x respectively represent the magnetic field components in the z- and x-propagation directions of the electromagnetic wave, E y and E x respectively represent the electric components in the z- and x-propagation directions of the electromagnetic wave, β is the propagation constant, and a is the length of the long side of the slit.

4. The method for analyzing and designing the shielding characteristics of a slotted shielding cavity according to claim 2, characterized in that, The TE 01 wave has a field distribution as follows: E y (x, y) = H x (x, y) = E z (x, y) = 0; where x, y, and z represent the three-dimensional coordinate values of the electromagnetic wave propagation, Hz and Hx respectively represent the magnetic field components in the z and x propagation directions of the electromagnetic wave, Ey and Ex respectively represent the electric field components in the y and x propagation directions of the electromagnetic wave, β is the propagation constant, and b is the length of the short side of the gap.

5. The method for analyzing and designing the shielding characteristics of a slotted shielding cavity according to claim 1, characterized in that, The step S4 includes: when the external electromagnetic wave is mainly horizontally polarized, the gap of the slotted shielding cavity is set to the horizontal direction; when the external electromagnetic wave is mainly vertically polarized, the gap of the slotted shielding cavity is set to the vertical direction.

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