Dual-passband reconfigurable frequency selection wave absorber structure and array thereof

Abstract

The invention discloses a dual-passband reconfigurable frequency selection wave absorber structure and an array thereof. The dual-passband reconfigurable frequency selection wave absorber structure comprises a controllable lossy wave absorbing layer and a controllable lossless frequency selection layer which are arranged at an interval from top to bottom, the upper surface and the lower surface of the controllable lossy wave absorbing layer are provided with butterfly-shaped metal patches which are arranged in a cross shape. The two ends of each butterfly-shaped metal patch are provided with T-shaped metal strips. A first resistor is arranged on the T-shaped metal strip to consume electromagnetic waves, first pin diodes are arranged at the joint of the T-shaped metal strip and the fan-shaped metal patch and the joint of the fan-shaped gap, a double-layer square gap with a sunken structure is formed in the metal patch on the upper surface of the controllable lossless frequency selection layer, and a second pin diode is arranged in the sunken structure; the first pin diode and the second pin diode are used for controlling the reconfigurable closing of the dual-passband. According to the invention, two low-insertion-loss passbands are provided, the broadband wave-absorbing characteristic is good, and reconfigurable closing of two transmission windows can be realized by controlling the PIN diodes, so that full-band invisibility is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of spatial filters, and particularly to a dual-band frequency selective absorber structure with a closable passband and its array. Background Art

[0002] The stealth design of radar sensors is a very important point for improving the survivability of flight platforms. Frequency selective surfaces are two-dimensional periodic array structures with spatial filtering performance, and are widely used as antenna radomes. Frequency selective surfaces can protect antennas while reducing the radar cross-section of antennas. However, with the development of radar technology, frequency selective surfaces that rely on scattering to reduce the monostatic radar cross-section gradually cannot meet the requirements of radar stealth. To eliminate out-of-band scattering, frequency selective absorber structures have been developed. Frequency selective absorber structures are usually a stacked structure, including a lossy layer at the top and a frequency selective layer at the bottom. The frequency selective absorber structure reduces the out-of-band radar cross-section by absorbing out-of-band incident waves, and can also ensure normal operation within the radar band.

[0003] With the rapid development of communication technologies such as dual-band duplex communication and multi-band satellite communication, frequency selective absorber structures with multiple transmission bands gradually have greater application advantages. The patent application with the publication number CN115117636A discloses a broadband frequency selective absorber with dual bands. This frequency selective absorber has dual bands and a wide absorption bandwidth, but its passbands are fixed and it does not have in-band stealth performance.

[0004] Currently, there have been many studies on dual-band frequency selective absorbers. However, due to the fixed passbands of passive frequency selective absorber structures, their in-band stealth performance is very poor; the current frequency selective absorbers with closable passbands mainly focus on single-band research, and they cannot be applied to the field of multi-frequency communication. There are few studies that can achieve the reconfigurable closure of dual-band transmission windows. Summary of the Invention

[0005] The purpose of the present invention is to provide a dual-band reconfigurable frequency selective absorber structure and its array, which have two transmission passbands and can be applied to the field of dual-frequency communication. It can achieve the effect of full-band stealth by closing the two transmission windows through PIN diodes.

[0006] To achieve the above task, the present invention adopts the following technical solutions:

[0007] A dual-band reconfigurable frequency selective absorber structure includes a controllable lossy absorber layer and a controllable lossless frequency selective layer that are arranged at intervals from top to bottom;

[0008] The upper and lower surfaces of the controllable lossy absorbing layer are provided with butterfly-shaped metal patches arranged in a cross shape, and T-shaped metal strips are arranged at both ends of the butterfly-shaped metal patches; a group of interconnected fan-shaped slits are arranged in the butterfly-shaped metal patches, and strip-shaped slits are distributed inside the fan-shaped slits; a first resistor is arranged on the T-shaped metal strip, and first pin diodes are arranged at the connection between the T-shaped metal strip and the fan-shaped metal patch and at the connection of the fan-shaped slits; a capacitor is also arranged on the fan-shaped slits;

[0009] On the upper surface metal patch of the controllable lossless frequency selective layer, a double-layer square slit with a concave structure is arranged, and a second pin diode is arranged in the concave structure; the middle part of the controllable lossless frequency selective layer is connected by a metal through hole to a "cross"-shaped DC feeding line arranged on the lower surface of the controllable lossless frequency selective layer, and a choke inductance is loaded on the DC feeding line.

[0010] Furthermore, the controllable lossy absorbing layer includes a first dielectric substrate, and the butterfly-shaped metal patches are arranged on both the upper and lower surfaces of the first dielectric substrate; the butterfly-shaped metal patch includes a group of fan-shaped metal patches arranged oppositely, and a group of T-shaped metal strips are symmetrically arranged outside the group of fan-shaped metal patches, and the T-shaped metal strips are arranged oppositely; the connection part of the fan-shaped metal patches is a disc structure, and fan-shaped slits are arranged in each fan-shaped metal patch and are connected by two arc-shaped slits at the disc structure.

[0011] Furthermore, a first resistor is arranged inside each T-shaped metal strip to dissipate electromagnetic waves, and first pin diodes are arranged at the connection between each T-shaped metal strip and the fan-shaped slit on the fan-shaped metal patch and at the two arc-shaped slits on the disc structure to control the reconfigurable closing of the dual passband; a capacitor is arranged between the fan-shaped slit and the edge of the fan-shaped metal patch to connect the first pin diodes and realize the DC feeding of the four first pin diodes; among them, the directions of the two first pin diodes located at the two arc-shaped slits on the disc structure both face the center point of the disc structure, and the directions of the other two first pin diodes are the same.

[0012] Furthermore, on the inner arc of a pair of fan-shaped slits on the butterfly-shaped metal patch, first strip-shaped slits are respectively opened in the directions of ±10°, ±20°, ±30°, ±150°, ±160° and ±170° to adjust the position of the high-frequency passband; a short and a long group of second strip-shaped slits are symmetrically arranged on the inner sides of the two side edges of each fan-shaped slit to adjust the position of the low-frequency passband, and these two groups of second strip-shaped slits are arranged along the direction perpendicular to the side edges.

[0013] Furthermore, the controllable lossless frequency selective layer includes a second dielectric substrate; the double-layer square slit with a concave structure includes a first square slit and a second square slit;

[0014] A first square slot is provided on the metal patch on the upper surface of the second dielectric substrate, and a second square slot is provided in the first square slot; wherein, each middle part of each side of the first square slot and the second square slot has a concave structure, and a second pin diode is provided in each concave structure.

[0015] Furthermore, by controlling the first pin diode and the second pin diode, the reconfigurable closing of two TE / TM transmission windows can be realized, thereby achieving full-band stealth.

[0016] Furthermore, when all the first pin diodes and the second pin diodes on the controllable lossy absorbing layer and the controllable lossless frequency selective layer are fully turned on, it shows dual-polarization TE / TM full-band absorption; when all the first pin diodes and the second pin diodes are fully turned off, each of the dual-polarization TE / TM has a low insertion loss transmission window.

[0017] A dual-band reconfigurable frequency selective absorber array is composed of the above-mentioned dual-band reconfigurable frequency selective absorber structures arranged in an array.

[0018] A radar system employs the above-mentioned dual-band reconfigurable frequency selective absorber array.

[0019] Compared with the prior art, the present invention has the following technical features:

[0020] The present invention provides a frequency selective absorber with dual bands applicable to multifunctional systems, having two low insertion loss passbands and good broadband absorption characteristics. By controlling the PIN diodes, the reconfigurable closing of two transmission windows can be realized, thereby achieving full-band stealth, which has important application values in the fields of electromagnetic compatibility and radar stealth. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the dual-band reconfigurable frequency selective absorber structure of the present invention;

[0022] Figure 2 It is a structural diagram of the controllable lossy absorbing layer of the present invention; wherein (a) is the upper surface and (b) is the lower surface;

[0023] Figure 3 It is a structural diagram of the controllable lossless frequency selective layer of the present invention; wherein (a) is the upper surface and (b) is the lower surface;

[0024] Figure 4 It is a structural diagram of the dual-band reconfigurable frequency selective absorber array with closable passbands of the present invention;

[0025] Figure 5It is the S-parameter diagram under different states at a normal incidence angle in an embodiment of the present invention, where (a) are the S-parameters of two polarization waves when the PIN diodes are all cut off, and (b) are the S-parameters of two polarization waves when the PIN diodes are all turned on. Detailed implementation manners

[0026] The present invention provides a dual-band reconfigurable frequency selective absorber structure, which includes a controllable lossy absorbing layer 1 and a controllable lossless frequency selective layer 2 that are arranged at intervals from top to bottom;

[0027] 1. Controllable lossy absorbing layer

[0028] The controllable lossy absorbing layer 1 includes a first dielectric substrate 11. Butterfly-shaped metal patches are arranged on both the upper surface and the lower surface of the first dielectric substrate 11, and the butterfly-shaped metal patches on the upper and lower surfaces are arranged in a cross shape; taking the butterfly-shaped metal patch on the upper surface as an example, the butterfly-shaped metal patch includes a group of fan-shaped metal patches 13 arranged oppositely, and a group of T-shaped metal strips 12 are symmetrically arranged outside the group of fan-shaped metal patches 13; the connection part of the fan-shaped metal patches 13 is a circular wafer structure 14, and a fan-shaped slit 15 is arranged in each fan-shaped metal patch 13 and is connected by two arc-shaped slits at the circular wafer structure 14; bar-shaped slits 16 are distributed on the inner side of the arc and the inner side of the side of each fan-shaped slit to adjust the positions of the high-frequency passband and the low-frequency passband; a first resistor 1-1 is arranged in each T-shaped metal strip 12 to dissipate electromagnetic waves, and a first pin diode 1-2 is arranged at the connection part of each T-shaped metal strip 12 and the fan-shaped slit 15 on the fan-shaped metal patch 13 and at the two arc-shaped slits on the circular wafer structure 14 to control the reconfigurable closing of the dual band; a capacitor 1-3 is arranged between the fan-shaped slit 15 and the edge of the fan-shaped metal patch 13 to connect the first pin diodes 1-2 and realize the DC feeding of the four first pin diodes 1-2; among them, the directions of the two first pin diodes 1-2 located at the two arc-shaped slits on the circular wafer structure 14 both face the center point of the circular wafer structure 14 (which is also the center of the butterfly-shaped metal patch), and the directions of the other two first pin diodes 1-2 are the same.

[0029] In an embodiment of the present invention, as Figure 2As shown in (a) and (b), the first dielectric substrate 11 has a square structure. The butterfly-shaped metal patches on the upper surface are arranged longitudinally, and the butterfly-shaped metal patches on the lower surface are arranged transversely. They are arranged in a cross shape and have the same structure. Each butterfly-shaped metal patch is composed of two opposite sector-shaped metal patches 13. The two sector-shaped metal patches 13 are concentric and spaced 180° apart, and have a disc structure 14 at the connection. Among them, the side length of the first dielectric substrate 11 is P = 20 mm. Each T-shaped metal strip 12 includes a strip arranged on the side of the first dielectric substrate 11 and a strip connected to the sector-shaped metal patch 13. The width of the strip arranged on the side of the first dielectric substrate 11 is W 11 = 0.5 mm, and the length is L S1 = 5 mm; the width of the strip connected to the sector-shaped metal patch 13 is W 12 = 0.5 mm.

[0030] In this solution, on the inner side of the arc of a pair of sector-shaped gaps on the butterfly-shaped metal patch, first strip-shaped gaps with a width of 0.1 mm are respectively opened in the directions of ±10°, ±20°, ±30°, ±150°, ±160° and ±170° to adjust the position of the high-frequency passband. The distance R from the bottom of these first strip-shaped gaps to the center of the butterfly-shaped metal patch 4 = 4 mm; the distance R from the inner side of the arc of the sector-shaped gap to the center of the metal patch 3 = 5.4 mm, the distance R from the outer side of the arc of the sector-shaped gap to the center of the metal patch 2 = 5.5 mm, and the radius of the sector-shaped metal patch 13 is R 1 = 6 mm.

[0031] The strip-shaped gap 16 includes a first strip-shaped gap and a second strip-shaped gap, where:

[0032] On the inner sides of the two side edges of each sector-shaped gap, a short and a long group of second strip-shaped gaps are symmetrically arranged to adjust the position of the low-frequency passband. These two groups of second strip-shaped gaps are arranged in a direction perpendicular to the side edge. The length L of the longer group of strip-shaped gaps 12 = 1.3 mm, and the length L of the shorter group of strip-shaped gaps 11 = 0.9 mm.

[0033] 2. Controllable lossless frequency selection layer

[0034] The controllable lossless frequency selective layer 2 includes a second dielectric substrate 21. A first square slot 22 is provided on the metal patch on the upper surface of the second dielectric substrate 21, and a second square slot 23 is provided in the first square slot 22. The double-passband controllable lossless frequency selective layer is realized by the double-square-slot structure. Among them, each middle part of each side of the first square slot 22 and the second square slot 23 has a recessed structure 24, and a second pin diode 2-1 is provided in each recessed structure 24. There is a metal through hole 2-2 in the middle of the second dielectric substrate 21, and the metal through hole 2-2 is connected to a cross-shaped DC feeding line 25 on the lower surface of the second dielectric substrate 21, and a choke inductor 2-3 is loaded on each section of the DC feeding line 25 to achieve high-frequency isolation.

[0035] In one embodiment of the present invention, as Figure 3 shown in (a) and (b), the second dielectric substrate 21 is a square structure with a side length of P = 20 mm; the first square slot 22 and the second square slot 23 are both square structures, and the outer side length of the first square slot 22 is L 21 = 13 mm, and the width of the side is 0.2 mm; the outer width of the recessed structure 24 on the first square slot 22 is W 21 = 4 mm, and the recessed depth L 22 = 1.4 mm; the outer side length of the second square slot is L 23 = 7.4 mm, and the width of the side is 0.1 mm; the outer width of the recessed structure 24 on the second square slot is W 22 = 1.6 mm, and the recessed depth L 24 = 2.5 mm.

[0036] The present invention has two low insertion loss passbands and good broadband microwave absorption characteristics. By controlling the first pin diode 1-2 and the second pin diode 2-1, the reconfigurable closing of the two transmission windows can be realized, so as to achieve full-band stealth, which has important application values in the fields of electromagnetic compatibility and radar stealth.

[0037] The double-passband reconfigurable frequency selective absorber structure has a total of two working states:

[0038] When all the first pin diodes 1-2 and the second pin diodes 2-1 on the controllable lossy absorber layer 1 and the controllable lossless frequency selective layer 2 are all turned on, it shows double-polarized TE / TM full-band absorption; when all the first pin diodes 1-2 and the second pin diodes 2-1 are all turned off, each of the double-polarized TE / TM has a low insertion loss transmission window. In the present invention, the TE polarization represents a uniform plane wave with the electric field direction being longitudinal, and the TM polarization represents a uniform plane wave with the electric field direction being transverse.

[0039] See the appendix Figure 4, the present invention also provides a dual-band reconfigurable frequency selective absorber array, which is composed of the designed dual-band reconfigurable frequency selective absorber structures arranged in an array.

[0040] In one embodiment of the present invention, the height of the air layer between the controllable lossy absorber layer 1 and the controllable lossless frequency selective layer 2 is H = 12.7 mm; the thickness of the controllable lossy absorber layer 1 is h m1 = 0.5 mm, and the thickness of the controllable lossless frequency selective layer 2 is h m2 = 1 mm; both the first dielectric substrate 11 and the second dielectric substrate 21 are made of Rogers 4350B material with a dielectric constant of 3.65 and a loss tangent of 0.0037.

[0041] The S parameters of the dual-band reconfigurable frequency selective absorber array in this embodiment are as Figure 5 shown. The frequency range where |S 11 | is less than -10 dB is 3 - 7.2 GHz. The two passbands are at 4.05 GHz and 5.25 GHz respectively, and the insertion losses at these two frequency points are 0.35 dB and 0.45 dB respectively. As Figure 5 (a) shows, when the eight PIN diodes in the controllable lossy absorber layer and the controllable lossless frequency selective layer are all cut off, TE and TM polarized waves respectively generate a transmission window at 4.05 GHz and 5.25 GHz, and the insertion losses are 0.35 dB and 0.45 dB respectively; as Figure 5 (b) shows, when the eight PIN diodes in the controllable lossy absorber layer and the controllable lossless frequency selective layer are all turned on, TE and TM polarized waves achieve full-band absorption in the range of 3 - 7.2 GHz, and the absorption rate is greater than 90%.

[0042] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A dual-passband reconfigurable frequency selective absorber structure, characterized in that: It comprises a controllable lossy absorbing layer (1) and a controllable lossless frequency selective layer (2) which are arranged at intervals from top to bottom; The upper and lower surfaces of the controllable lossy absorbing layer (1) are provided with butterfly-shaped metal patches arranged in a cross shape, and T-shaped metal strips (12) are provided at both ends of the butterfly-shaped metal patches; a group of mutually connected fan-shaped gaps (15) are provided in the butterfly-shaped metal patches, and strip-shaped gaps (16) are distributed inside the fan-shaped gaps (15); a first resistor (1-1) is provided on the T-shaped metal strip (12), and a first pin diode (1-2) is provided at the connection between the T-shaped metal strip (12) and the fan-shaped metal patch (13) and at the connection between the fan-shaped gaps (15); and a capacitor (1-3) is also provided on the fan-shaped gaps (15); A double-layer square gap with a recessed structure (24) is arranged on the metal patch on the upper surface of the controllable lossless frequency selection layer (2), and a second pin diode (2-1) is arranged in the recessed structure (24); the middle part of the controllable lossless frequency selection layer (2) is connected to a "cross"-shaped DC feed line (25) arranged on the lower surface of the controllable lossless frequency selection layer (2) by means of a metal through hole (2-2), and an Eccentric inductor (2-3) is loaded on the DC feed line (25).

2. The dual-passband reconfigurable frequency selective absorber structure according to claim 1, characterized in that: The controllable lossy absorbing layer (1) comprises a first dielectric substrate (11), and the butterfly-shaped metal patch is arranged on the upper surface and the lower surface of the first dielectric substrate (11); the butterfly-shaped metal patch comprises a group of fan-shaped metal patches (13) arranged opposite to each other, and a group of T-shaped metal strips (12) are symmetrically arranged outside the group of fan-shaped metal patches (13), and the T-shaped metal strips (12) are arranged opposite to each other; the connection of the fan-shaped metal patches (13) is a disc structure (14), and a fan-shaped gap (15) is arranged in each fan-shaped metal patch (13), and the fan-shaped gaps (15) are connected at the disc structure (14) through two arc-shaped gaps.

3. The dual-passband reconfigurable frequency selective absorber structure according to claim 1, characterized in that: A first resistor (1-1) is arranged in each T-shaped metal strip (12) for loss of electromagnetic waves, and a first pin diode (1-2) is arranged at the connection between each T-shaped metal strip (12) and the fan-shaped gap (15) on the fan-shaped metal patch (13) and at two arc-shaped gaps on the disc structure (14) for controlling the reconfigurable closing of the dual passband; a capacitor (1-3) is arranged between the fan-shaped gap (15) and the edge of the fan-shaped metal patch (13) for connecting the first pin diode (1-2) to realize direct current feeding of the four first pin diodes (1-2); wherein the two first pin diodes (1-2) located at the two arc-shaped gaps on the disc structure (14) are both oriented toward the center point of the disc structure (14), and the directions of the other two first pin diodes (1-2) are the same.

4. The dual-passband reconfigurable frequency selective absorber structure according to claim 1, characterized in that: A first strip slot is respectively provided on the inner side of the circular arc of a pair of fan-shaped slots (15) on the butterfly-shaped metal patch in the directions of ±10°, ±20°, ±30°, ±1150°, ±1160° and ±1170° to adjust the position of the high-frequency passband; two groups of second strip slots, one short and one long, are symmetrically arranged on the inner side of the two side edges of each fan-shaped slot (15) to adjust the position of the low-frequency passband, and the two groups of second strip slots are arranged in a direction perpendicular to the side edges.

5. The dual-passband reconfigurable frequency selective absorber structure according to claim 1, characterized in that: The controllable lossless frequency selection layer (2) comprises a second dielectric substrate (21); the double-layer square slits with a recessed structure (24) comprise a first square slit (22) and a second square slit (23); A first square slit (22) is provided on the metal patch on the upper surface of the second dielectric substrate (21), and a second square slit (23) is provided in the first square slit (22); wherein a recessed structure (24) is provided in the middle of each side of the first square slit (22) and the second square slit (23), and a second pin diode (2-1) is provided in each recessed structure (24).

6. The dual-passband reconfigurable frequency selective absorber structure according to claim 1, characterized in that: By controlling the first pin diode (1-2) and the second pin diode (2-1), reconfigurable closing of the two TE / TM transmission windows can be achieved, thereby achieving full-band stealth.

7. The dual-passband reconfigurable frequency selective absorber structure according to claim 6, characterized in that: When all the first pin diodes (1-2) and the second pin diodes (2-1) on the controllable lossy absorbing layer (1) and the controllable lossless frequency selective layer (2) are fully turned on, dual-polarization TE / TM full-band absorbing is achieved; when all the first pin diodes (1-2) and the second pin diodes (2-1) are fully turned off, the dual-polarization TE / TM each has a low insertion loss transmission window.

8. A dual-passband reconfigurable frequency selective absorber array, characterized in that: The absorber array is composed of the dual-passband reconfigurable frequency selective absorber structures according to any one of claims 1 to 7 arranged in an array.

9. A radar system, characterized in that: The system adopts the dual-passband reconfigurable frequency selective absorber array according to claim 8.

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