A dual-passband frequency selective surface structure and its unit structure

Abstract

A dual-passband frequency selective surface structure and its unit structure, belonging to the field of electromagnetic wave technology, characterized in that: it comprises a metal layer and a dielectric substrate arranged in sequence from top to bottom; a cross-shaped slot and a step-shaped slot are provided on the metal layer; the center of the cross-shaped slot coincides with the center of the metal layer; there are four step-shaped slots, which are respectively located in four areas separated by the cross-shaped slot and are arranged in sequence rotated 90° around the center of the structure; the cross-shaped slot is connected to the step-shaped slot. The dual-passband frequency selective surface structure of the present invention has extremely strong filtering characteristics near the two frequency points of 6.7GHz and 18.1GHz, and can protect the satellite communication signals working at these two frequency points from being interfered by other frequency signals. There is no deviation in the resonant frequency when the TE and TM polarized incident waves are vertically irradiated. In the TE and TM modes, the resonant frequency and bandwidth change slightly when the incident waves are irradiated at different angles, and there is no effect on the structural performance.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic waves, and in particular relates to a dual-passband frequency selective surface structure and a unit structure thereof. Background Art

[0002] Frequency Selective Surface (FSS) is a two-dimensional periodic array structure that allows electromagnetic waves to pass through with no loss or low loss in a specific frequency band, while shielding and reflecting electromagnetic waves outside the frequency band. It can effectively control the transmission and reflection of electromagnetic waves, similar to a spatial filter. Due to its unique filtering characteristics, FSS can be widely used in electromagnetic protection, electromagnetic compatibility, antennas, filters, etc.

[0003] Satellite communication mainly refers to radio communication between earth stations or earth stations and spacecraft through communication satellites to forward signals. Satellite communication mainly includes four modes: satellite relay communication, satellite direct broadcasting, satellite mobile communication and satellite fixed communication. The working frequency bands used for satellite communication are mainly: centimeter wave band, with a frequency range of 3-30GHz. This band corresponds to the IEEE S (2-4GHz), C (4-8GHz), Ku (12-18GHz), K (18-27GHz) and Ka (26.5-40GHz) bands.

[0004] The shortcomings of existing frequency selective surfaces used in satellite communication frequency bands are that their filtering frequency bands are single and their structural stability is poor, which cannot meet the requirements of more scenarios and higher performance. In addition, the existing FSS structural units are large in size and can no longer meet the current demand for miniaturized structures. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a dual-passband frequency selective surface structure and a unit structure thereof. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0006] In a first aspect, the present invention provides a dual-passband frequency selective surface unit structure, comprising a metal layer and a dielectric substrate arranged in sequence from top to bottom; a cross-shaped gap and a step-shaped gap are provided on the metal layer; the center of the cross-shaped gap coincides with the center of the metal layer; a total of four step-shaped gaps are provided, which are respectively located in four areas separated by the cross-shaped gap and are arranged in sequence rotated 90° around the center of the structure; the cross-shaped gap (11) is connected to the step-shaped gap (21).

[0007] Furthermore, in the dual-passband frequency selective surface unit structure of the present invention, the cross-shaped slot is both an axisymmetric structure and a centrosymmetric structure.

[0008] Furthermore, in the dual-passband frequency selective surface unit structure of the present invention, the stepped gap is an axisymmetric structure.

[0009] Furthermore, in the dual-passband frequency selective surface unit structure of the present invention, the stepped slots include a first rectangular slot, a second rectangular slot, two third rectangular slots, two fourth rectangular slots and a fifth rectangular slot; the second rectangular slot, the third rectangular slot, the fourth rectangular slot, and the fifth rectangular slot are arranged in parallel with equal intervals; the second rectangular slot, the third rectangular slot, the fourth rectangular slot and the fifth rectangular slot are all arranged perpendicular to the first rectangular slot.

[0010] Furthermore, in the dual-passband frequency selective surface unit structure of the present invention, the cross-shaped slot and the step-shaped slot are connected by a first rectangular slot.

[0011] Furthermore, in the dual-passband frequency selective surface unit structure of the present invention, the first rectangular slot is arranged perpendicular to the aforementioned cross-shaped slot.

[0012] Furthermore, in the dual-passband frequency selective surface unit structure of the present invention, the dielectric substrate is made of a flame-resistant material; the metal layer is made of a metal; and the metal includes copper, aluminum or gold.

[0013] Furthermore, in the dual-passband frequency selective surface unit structure of the present invention, the metal layer and the dielectric substrate are both square structures.

[0014] Furthermore, in the dual-passband frequency selective surface unit structure of the present invention, the size of the metal layer and the dielectric substrate are both 8mm*8mm. The size of the frequency selective surface structure is very small, and the surface size of the unit structure is only 8mm*8mm, which meets the trend of miniaturization structure.

[0015] In a second aspect, the present invention provides a dual-passband frequency selective surface structure, comprising M×N periodically arranged frequency selective surface unit structures as described in any one of the first aspects, wherein M and N are integers greater than or equal to 1.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The dual-passband frequency selective surface structure of the present invention has extremely strong filtering characteristics near the two frequency points of 6.7 GHz and 18.1 GHz, and can protect the satellite communication signals working at these dual frequency points from being interfered by other frequency signals.

[0018] 2. The dual-passband frequency selective surface structure of the present invention has very good polarization stability. When the TE and TM polarized incident waves are vertically irradiated, the resonant frequency has no deviation and has no effect on the structural performance.

[0019] 3. The dual-passband frequency selective surface structure of the present invention has very good angular stability. In TE and TM modes, the resonant frequency and bandwidth change slightly when incident waves are irradiated at different angles, and have no effect on the structural performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A three-dimensional diagram of a dual-passband frequency selective surface unit structure according to an embodiment of the present invention;

[0021] Figure 2 A side view of a dual-passband frequency selective surface unit structure according to an embodiment of the present invention;

[0022] Figure 3 It is a front view of the metal layer of the dual-passband frequency selective surface unit structure according to an embodiment of the present invention;

[0023] Figure 4 A three-dimensional diagram of a dual-passband frequency selective surface multi-unit structure according to an embodiment of the present invention;

[0024] Figure 5 This is a simulation diagram of the filtering performance of the dual-passband frequency selective surface structure in the TE polarization mode according to an embodiment of the present invention;

[0025] Figure 6 This is a simulation diagram of the filtering performance of the dual-passband frequency selective surface structure in the TM polarization mode according to an embodiment of the present invention;

[0026] Figure 7 This is a simulation diagram of the angular stability performance of the dual-passband frequency selective surface structure in the TE polarization mode according to an embodiment of the present invention;

[0027] Figure 8 is a simulation diagram of the angular stability performance of the dual-passband frequency selective surface structure in the TM polarization mode according to an embodiment of the present invention;

[0028] Among them, 1 is a metal layer; 11 is a cross-shaped gap; 2 is a dielectric substrate; 21 is a step-shaped gap; 211 is a first rectangular gap; 212 is a second rectangular gap; 213 is a third rectangular gap; 214 is a fourth rectangular gap; and 215 is a fifth rectangular gap. DETAILED DESCRIPTION

[0029] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the dual-passband frequency selective surface structure and its unit structure proposed by the present invention are described in detail in combination with the accompanying drawings and specific embodiments. In the disclosed embodiment, the dual passbands are C band and K band.

[0030] The above and other technical contents, features and effects of the present invention are clearly presented in the following detailed description of the specific implementation modes in conjunction with the accompanying drawings. Through the description of the specific implementation modes, the technical means and effects adopted by the present invention to achieve the predetermined purpose can be more deeply and specifically understood. However, the attached drawings are only for reference and explanation purposes and are not used to limit the technical solutions of the present invention.

[0031] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed. In the absence of more restrictions, the elements defined by the statement "including one..." do not exclude the existence of other identical elements in the article or device including the elements.

[0032] like Figure 1 , Figure 2 , Figure 3 As shown, the frequency selective surface unit structure of the present embodiment includes a metal layer 1 and a dielectric substrate 2 from top to bottom. In the disclosed embodiment, the dielectric substrate 2 is made of a flame-resistant material with a relative dielectric constant of 4.4 and an electric cutting loss of 0.02. The metal layer 1 is made of copper (Cu). Both the metal layer 1 and the dielectric substrate 2 are square structures, and the surface dimensions are both 8mm*8mm. In addition, in the present embodiment, the thickness of the dielectric substrate 2 is 0.2mm; the thickness of the metal layer 1 is in the range of 0.017mm-0.035mm. The frequency selective surface unit structure of the present embodiment is very small, and the surface dimension of the unit structure is only 8mm*8mm, which meets the current trend of miniaturization of device structures.

[0033] In the disclosed embodiment, a cross-shaped gap 11 and a step-shaped gap 21 are provided on the metal layer 1, and the center of the cross-shaped gap coincides with the center of the metal layer; there are four step-shaped gaps in total, which are respectively located in four areas separated by the cross-shaped gap and are arranged to be rotated 90° around the center of the structure.

[0034] In the disclosed embodiment, the cross-shaped slit 11 is both an axisymmetric structure and a centrally symmetrical structure. The step-shaped slit 21 is an axisymmetric structure; the step-shaped slit 21 is composed of a first rectangular slit 211, two second rectangular slits 212, two third rectangular slits 213, two fourth rectangular slits 214 and a fifth rectangular slit 215. The cross-shaped slit 11 and the step-shaped slit 21 are connected by the first rectangular slit 211. The first rectangular slit 211 is perpendicular to the cross-shaped slit 21. The second rectangular slit 212, the third rectangular slit 213, the fourth rectangular slit 214 and the fifth rectangular slit 215 are arranged in parallel at equal intervals. The second rectangular slit 212, the third rectangular slit 213, the fourth rectangular slit 214 and the fifth rectangular slit 215 are all arranged perpendicular to the first rectangular slit 211.

[0035] Table 1 below shows the detailed geometric parameters of the metal layer 1 provided in the embodiment of the present disclosure.

[0036] Table 1. Detailed geometric parameters of the metal layer (unit: mm)

[0037] parameter W1 W2 W3 W4 value 0.2 0.2 0.2 0.3 parameter L1 L2 L3 L4 value 7.6 0.8 1.6 2.4 parameter L5 DX DY value 3.2 8.0 8.0

[0038] Another disclosed embodiment of the present invention provides a dual-passband frequency selective surface multi-unit structure applied to C-band and K-band, wherein the frequency selective surface structure comprises M×N periodically arranged frequency selective surface unit structures as described in any one of the above embodiments, wherein M and N are integers greater than or equal to 1. Figure 4 As shown, in this embodiment, the frequency selective surface structure includes 5×5 unit structures; in specific applications, the frequency selective surface structure may include 10×10, 20×20, 40×40, or even more of the above unit structures according to actual needs.

[0039] In order to verify the performance of the frequency selective surface structure (FSS structure) of the present embodiment, the present disclosure embodiment uses the commercial simulation software HFSS to perform multiple performance simulation analyses on the FSS structure.

[0040] Figure 5 is a simulation diagram of the filtering performance of the dual-passband frequency selective surface structure applied to the C band and the K band in the TE polarization mode provided by this embodiment; Figure 5It can be seen from the return loss (S11) and insertion loss (S21) in that the two resonant frequencies of the FSS structure of this embodiment are 6.7GHz and 18.1GHz. At the 6.7GHz resonance point, the return loss is -23.39dB, and the bandwidth is 560MHz at -10dB; at the 18.1GHz resonance point, the return loss is -21.62dB, and the bandwidth is 1005MHz at -10dB. In other words, in the TE polarization mode, the FSS structure has a perfect transmission effect for signals with frequencies around 6.7GHz and 18.1GHz, and can well resist the interference of out-of-band signals.

[0041] Figure 6 FIG. 1 is a simulation diagram of the filtering performance of a dual-passband frequency selective surface structure applied to C-band and K-band in TM polarization mode provided by an embodiment of the present invention. Figure 6 It can be seen from the return loss (S11) and insertion loss (S21) in that the two resonant frequencies of the FSS structure of this embodiment are 6.7GHz and 18.1GHz. At the 6.7GHz resonance point, the return loss is -22.99dB, and the bandwidth is 568MHz at -10dB; at the 18.1GHz resonance point, the return loss is -21.51dB, and the bandwidth is 1018MHz at -10dB. In other words, in the TM polarization mode, the FSS structure has a perfect transmission effect for signals around the 6.7GHz and 18.1GHz frequency points, and can well resist the interference of out-of-band signals.

[0042] comprehensive Figure 5 and Figure 6 From the performance simulation diagram, it can be seen that this structure has dual-passband performance in TE mode and TM mode, and the two resonant frequencies are always in the C band and K band, that is, it has excellent polarization stability.

[0043] Furthermore, in order to study the angular stability of the FSS structure of this embodiment, it is irradiated with incident waves at incident angles of 0°, 15°, 30°, and 45° in the TE mode and the TM mode, and the frequency characteristics of the structure can be obtained. Figure 7 It is a simulation diagram of the angular stability performance of a dual-passband frequency selective surface structure applied to C-band and K-band in TE polarization mode provided by an embodiment of the present invention; Figure 8This is a simulation diagram of the angular stability performance of the dual-passband frequency selective surface structure applied to the C-band and K-band in the TM polarization mode provided by an embodiment of the present invention. The FSS structure has strong angular stability and excellent filtering characteristics at 6.7GHz and 18.1GHz. Under the irradiation of electromagnetic incident waves at different angles, the frequency deviation is within an acceptable range, and it has excellent signal transmission capability and anti-interference capability. Table 2 is the detailed geometric parameters of the angular stability simulation of the FSS structure in the TE mode of the embodiment of the present disclosure.

[0044] Table 2. Angular stability simulation parameters of FSS structure in TE mode

[0045]

[0046] from Figure 8 It can be seen that the FSS structure still has excellent angular stability and filtering characteristics at 6.7 GHz and 18.1 GHz. Under the irradiation of electromagnetic incident waves at different angles, the frequency deviation is within an acceptable range, and it has excellent signal transmission capability and anti-interference capability. Table 3 is the detailed geometric parameters of the angular stability simulation of the FSS structure of the embodiment of the present disclosure in the TM mode.

[0047] Table 3. Angular stability simulation parameters of FSS structure in TM mode

[0048]

[0049] comprehensive Figure 7 and Figure 8 It can be seen from the performance simulation diagram and the simulation parameters in Tables 2 and 3 that this FSS structure always has a dual-passband effect in the C-band and K-band when irradiated with incident waves at incident angles of 0°, 15°, 30° and 45° in TE mode and TM mode, and has excellent filtering performance, which means that this structure has excellent angular stability.

[0050] The dual-passband frequency selective surface structure applied to the C-band and K-band of the embodiment of the present disclosure has extremely strong filtering characteristics near the 6.7 GHz and 18.1 GHz frequency points, which can effectively prevent satellite communication signals from being interfered with by other frequency signals.

[0051] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A dual-passband frequency selective surface unit structure, characterized in that: It comprises a metal layer (1) and a dielectric substrate (2) arranged in sequence from top to bottom; the metal layer (1) is provided with a cross-shaped gap (11) and a step-shaped gap (21); the center of the cross-shaped gap (11) coincides with the center of the metal layer (1); There are four stepped slits (21) in total, which are respectively located in four areas separated by the cross-shaped slits and are arranged in sequence rotated 90 degrees around the structure center; the cross-shaped slit (11) is connected to the stepped slit (21); the stepped slit (21) includes a first rectangular slit (211), two second rectangular slits (212), two third rectangular slits (213), two fourth rectangular slits (214) and a fifth rectangular slit (215); the second rectangular slit (212), the third rectangular slit (213), the fourth rectangular slit (214) and the fifth rectangular slit (215) are arranged in parallel with equal spacing; the second rectangular slit (212), the third rectangular slit (213), the fourth rectangular slit (214) and the fifth rectangular slit (215) are all arranged perpendicular to the first rectangular slit (211).

2. The dual-passband frequency selective surface unit structure according to claim 1, characterized in that: The cross-shaped gap (11) is both an axisymmetric structure and a centrosymmetric structure.

3. The dual-passband frequency selective surface unit structure according to claim 1, characterized in that: The stepped gap (21) is an axisymmetric structure.

4. The dual-passband frequency selective surface unit structure according to claim 1, characterized in that: The cross-shaped gap (11) and the step-shaped gap (21) are connected via a first rectangular gap (211).

5. The dual-passband frequency selective surface unit structure according to claim 1, characterized in that: The first rectangular slit (211) is arranged perpendicular to the aforementioned cross-shaped slit (11).

6. The dual-passband frequency selective surface unit structure according to claim 1, characterized in that: The dielectric substrate (2) is made of flame-resistant material; the metal layer (1) is made of metal; the metal includes copper, aluminum or gold.

7. The dual-passband frequency selective surface unit structure according to claim 1, characterized in that: The metal layer (1) and the dielectric substrate (2) are both square structures.

8. The dual-passband frequency selective surface unit structure according to claim 1, characterized in that: The sizes of the metal layer (1) and the dielectric substrate (2) are both 8 mm*8 mm.

9. A dual-passband frequency selective surface structure, characterized in that: include M×N A periodically arranged dual-passband frequency selective surface unit structure as claimed in any one of claims 1 to 8, wherein M and N are integers greater than or equal to 1.

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