An energy-protective, ultra-wideband stealth surface structure

Abstract

The present invention discloses an integrated ultra-wideband stealth surface structure with energy protection, comprising: an absorbing layer for resonating with incident electromagnetic waves to form a passband frequency and performing broadband absorption of electromagnetic waves outside the passband frequency; a passband frequency selective surface layer for selecting electromagnetic waves with the same passband frequency as the absorbing layer and totally reflecting electromagnetic waves in the remaining frequency bands; and an energy switching layer for adjusting the resonant frequency of the structure to control the state of the overall transmission band, thereby selecting energy for incident electromagnetic waves within the passband frequency. The metasurface structure designed in the present invention not only has a broadband stealth effect, but also has a relatively wide passband, and can achieve energy protection by controlling the on and off of this passband.

Description

Technical Field

[0001] The present invention relates to the field of artificial electromagnetic materials, and in particular to an energy-shielding integrated ultra-wideband stealth surface structure. Background Art

[0002] Artificial electromagnetic materials are composite materials composed of periodically arranged subwavelength structures. As electromagnetic devices gradually develop towards miniaturization, lightweighting, and conformality, reducing three-dimensional artificial electromagnetic materials to a two-dimensional plane has become an effective way to broaden their practical applications. Thus, the concept of metasurfaces was born. In 2008, Nilandy et al. first proposed a metasurface absorber using a metal split ring on the surface and a metal strip on the back, achieving perfect absorption of incident electromagnetic waves at a single frequency. This innovative work has inspired more researchers to use metasurfaces for wave absorption research. With the deepening of current research, metasurface absorbers are gradually developing in the direction of broadband, wide-angle, and polarization-insensitive features.

[0003] Nowadays, many ultra-wideband absorbing metasurfaces can achieve good broadband absorbing effects and thus achieve stealth functions. However, many military applications now require not only stealth functions, but also their own communication frequency bands, such as various radar antennas. Moreover, with the rapid development of high-power microwave weapons, their communication frequency bands may also be damaged by high-power signals. Therefore, there is an urgent need to ensure that the metasurface can achieve stealth functions while also providing energy protection for itself. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides an integrated absorbent and penetrating ultra-wideband stealth surface structure with energy protection function, which not only has a wide-band stealth effect, but also has energy protection function.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] An energy-protective, absorbent, and ultra-wideband stealth surface structure comprising:

[0007] The wave absorbing layer is used to resonate with the incident electromagnetic wave to form a bandpass frequency and perform broadband absorption of electromagnetic waves outside the bandpass frequency;

[0008] The bandpass frequency selective surface layer is used to select electromagnetic waves with the same bandpass frequency as the absorbing layer and to fully reflect electromagnetic waves in other frequency bands;

[0009] The energy switching layer is used to adjust the resonant frequency of the structure to control the state of the overall transparent band, so as to select the energy of the incident electromagnetic waves within the bandpass frequency.

[0010] Furthermore, the absorbing layer includes a first dielectric plate, an interdigital structure is provided in the middle portion of the first dielectric plate, interdigital arm structures are provided at both ends of the interdigital structure, and the interdigital structure and the interdigital arm structures are connected via a lumped resistor.

[0011] Furthermore, the equivalent circuit of the absorbing layer is specifically:

[0012] The interdigital structure is equivalent to a parallel structure of a second capacitor and a second inductor;

[0013] The lumped resistance is equivalent to the first resistance;

[0014] The interdigital arm is equivalent to a series structure of a first capacitor and a first inductor;

[0015] The parallel structure of the second capacitor and the second inductor, the first resistor, and the series structure of the first capacitor and the first inductor are sequentially connected in series to form an equivalent circuit of the absorbing layer.

[0016] Furthermore, the bandpass frequency selective surface layer includes a second dielectric plate covered with a copper film, an I-shaped groove is provided in the middle portion of the second dielectric plate, and the I-shaped groove and the covering copper film form an I-shaped groove structure.

[0017] Furthermore, the equivalent circuit of the I-shaped groove structure is specifically a third capacitor and a third inductor connected in parallel, and the third capacitor and the third inductor connected in parallel constitute a bandpass frequency selective surface layer equivalent circuit; the bandpass frequency selective surface layer equivalent circuit is connected in parallel with the absorbing layer equivalent circuit.

[0018] Furthermore, the energy switching layer includes a third dielectric plate, and a first ladder structure and a second ladder structure are symmetrically arranged on the front of the third dielectric plate, and the connecting part of the first ladder structure and the second ladder structure is grooved in the middle position and loaded with a switching diode; the back of the third dielectric plate is parallel to the first strip structure and the second strip structure.

[0019] Furthermore, the equivalent circuit of the energy switch layer is specifically:

[0020] The first ladder structure and the second ladder structure are equivalent to a fourth capacitor and a control switch connected in series in parallel; the control switch parallel structure is two identical fourth inductor-switching diode-fourth inductor structures connected in parallel, and the fourth inductor-switching diode-fourth inductor structure is a fourth inductor connected in series at each end of the switching diode;

[0021] The first strip structure and the second strip structure are equivalent to a fifth inductor;

[0022] The fourth capacitor and the control switch connected in series are connected in parallel with the fifth inductor to form an energy switch layer equivalent circuit;

[0023] The energy switch layer equivalent circuit is connected in parallel with the absorbing layer equivalent circuit and the bandpass frequency selective surface layer equivalent circuit.

[0024] Furthermore, the period of the energy switch layer structure is half of the overall period.

[0025] The beneficial effects of the present invention are:

[0026] (1) The metasurface structure designed in the present invention has both wave-absorbing and wave-transmitting functions, and can achieve excellent broadband stealth effects;

[0027] (2) The metasurface structure designed in the present invention increases the lumped resistor and the diode, and the synergistic effect of the two can achieve the effect of energy protection by controlling the on and off of the wide passband through the diode in a wide passband. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a diagram of an ultra-wideband stealth surface structure with energy protection function.

[0029] Figure 2 is the structural diagram of the absorbing layer;

[0030] Figure 3 This is an equivalent circuit diagram of an ultra-wideband stealth surface with energy protection function and integrated absorption and penetration;

[0031] Figure 4 Select the surface layer structure map for the bandpass frequency;

[0032] Figure 5 The front and back structural diagrams of the energy switch layer;

[0033] Figure 6 This is the structural diagram of the back side of the energy switch layer. DETAILED DESCRIPTION

[0034] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0035] like Figure 1 As shown, an integrated ultra-wideband stealth surface structure with energy protection function includes an absorbing layer, a bandpass frequency selective surface layer, and an energy switch layer. There is an air layer between the absorbing layer and the bandpass frequency selective surface layer, and there is an air layer between the bandpass frequency selective surface layer and the energy switch layer. The details are as follows:

[0036] The absorbing layer is used to resonate with the incident electromagnetic wave to form a bandpass frequency and perform broadband absorption of electromagnetic waves outside the bandpass frequency.

[0037] In an optional embodiment of the present invention, the absorbing layer is an interdigital structure resonator loaded with a lumped resistor, such as Figure 2 As shown, it consists of an interdigital structure in the middle, lumped resistor elements on either side of the interdigital structure, and interdigital arms at both ends. When the interdigital structure resonates, the surface current does not flow through the lumped resistors, resulting in a passband characteristic. When the interdigital structure does not resonate, the absorber layer as a whole resonates, and the surface current flows between the interdigital structure and the interdigital arms through the lumped resistors. This converts the incident electromagnetic wave energy into heat energy and dissipates it, creating a broadband absorption effect. In addition, the addition of the lumped resistors ensures that the impedance of the overall structure matches that of free space in the operating frequency band, achieving a low reflection effect.

[0038] The wave absorbing layer comprises a first dielectric plate, an interdigital structure is arranged in the middle of the first dielectric plate, interdigital arm structures are arranged at both ends of the interdigital structure, and the interdigital structure and the interdigital arm structures are connected through a lumped resistor.

[0039] Specifically, the interdigital structure is used to generate resonance so that electromagnetic waves at the resonant frequency can be transmitted with low loss.

[0040] The interdigital structure is in the shape of an interdigital structure. Figure 2 The medium bright part is the copper film, which has a thickness of 0.035 mm and a conductivity of 5.8×10 3 S / m, the dark part is the dielectric material of the absorbing layer.

[0041] The lumped resistor is set in the middle position of the interdigital structure and the interdigital arm to absorb electromagnetic waves outside the passband frequency. In the present invention, two lumped resistors are set on both sides of the interdigital structure and in the middle position of the interdigital structure and the interdigital arm, such as Figure 2 As shown in the figure, the black part is the lumped resistor. Because the electric field of electromagnetic waves changes alternately, setting these two lumped resistors can improve the absorption effect.

[0042] The interdigital arms are used to adjust the absorbing performance of the absorbing layer structure. The interdigital arms are set at both ends of the interdigital structure, such as Figure 2 As shown, the interdigital arms are two bright strips above and below the lumped resistor. The present invention can adjust the absorbing performance of the absorbing layer structure by changing the length and gap size of the interdigital arms.

[0043] The equivalent circuit of the absorbing layer is as follows:

[0044] The interdigital structure is equivalent to a parallel structure of a second capacitor and a second inductor.

[0045] Specifically, the interdigital structure in the present invention can be equivalent to a parallel structure of a second capacitor and a second inductor, such as Figure 3 As shown, the second capacitor is C2 and the second inductor is L2.

[0046] By calculating the values ​​of the second capacitor C2 and the second inductor L2, the present invention can convert the structural parameters of the interdigital structure with the values ​​of the second capacitor C2 and the second inductor L2 in the equivalent circuit, thereby optimizing the transmission band frequency and bandwidth in combination with the equivalent circuit. The calculation formula is:

[0047] C = 3.937 × 10 -5 (ε r +1)l[0.11(n-3)+0.252]

[0048]

[0049] Where: C is the second capacitance value, s r is the relative dielectric constant of the absorbing layer medium, l is the length of the interdigital resonant structure, n is the number of interdigital fingers, L is the second inductance value, and w is the width of the interdigital strip.

[0050] The lumped resistance is equivalent to the first resistance.

[0051] The interdigital arm is equivalent to a series structure of a first capacitor and a first inductor.

[0052] The parallel structure of the second capacitor and the second inductor, the first resistor, and the series structure of the first capacitor and the first inductor are sequentially connected in series to form an equivalent circuit of the absorbing layer.

[0053] The bandpass frequency selective surface layer is used to select electromagnetic waves with the same bandpass frequency as the absorbing layer and to totally reflect electromagnetic waves in other frequency bands.

[0054] In an optional embodiment of the present invention, the passband of the bandpass frequency selective surface layer is the same as the passband of the absorbing layer, and it is fully reflected in the remaining frequency bands, which is equivalent to the metal reflective surface of the metasurface structure designed by the present invention.

[0055] The bandpass frequency selective surface layer comprises a second dielectric plate covered with a copper film, an I-shaped groove is arranged in the middle of the second dielectric plate, and the I-shaped groove and the covering copper film form an I-shaped groove structure.

[0056] like Figure 4 As shown, the bright part is the copper cladding layer, and the middle part is grooved to form an I-shaped shape, which is shown as the dark part, that is, the bandpass frequency selective surface layer dielectric material.

[0057] The equivalent circuit of the I-shaped groove structure is specifically a third capacitor and a third inductor connected in parallel, which constitute a bandpass frequency selective surface layer equivalent circuit; the bandpass frequency selective surface layer equivalent circuit is connected in parallel with the absorbing layer equivalent circuit.

[0058] Specifically, if Figure 3 As shown, the third capacitor is C3 in the figure, the third inductor is L3 in the figure, and the third capacitor C3 and the third inductor L3 form a parallel structure.

[0059] The energy switching layer is used to adjust the resonant frequency of the structure to control the state of the overall transparent band, so as to select the energy of the incident electromagnetic waves within the bandpass frequency.

[0060] In an optional embodiment of the present invention, the energy switching layer consists of a front structure and a back structure. A PIN switching diode is loaded into the central slot of the front structure. The diode's switching on and off changes the resonant frequency of the front structure, thereby altering the overall wave transmission band of the metasurface designed in this invention. Therefore, the PIN switching diode can provide energy protection against incident electromagnetic waves within the passband.

[0061] The energy switch layer includes a third dielectric plate, on the front of which a first ladder structure and a second ladder structure are symmetrically arranged, and a connecting portion between the first ladder structure and the second ladder structure is grooved in the middle and loaded with a switching diode; on the back of the third dielectric plate, a first strip structure and a second strip structure are parallelly arranged.

[0062] Specifically, if Figure 5 As shown, the first ladder-shaped structure and the second ladder-shaped structure are bright parts, namely the covered copper film, wherein the slotted parts are loaded with switching diodes, and the dark parts are the dielectric material of the energy switching layer.

[0063] Specifically, if Figure 6 As shown, the first strip structure and the second strip structure are two long lines of bright parts, namely the covered copper film, and the dark part is the dielectric material of the energy switch layer.

[0064] The equivalent circuit of the energy switching layer is as follows:

[0065] The first ladder structure and the second ladder structure are equivalent to a fourth capacitor and a control switch parallel structure connected in series; the control switch parallel structure is two identical fourth inductor-switching diode-fourth inductor structures connected in parallel, and the fourth inductor-switching diode-fourth inductor structure is a fourth inductor connected in series at both ends of the switching diode.

[0066] Specifically, if Figure 3 As shown, the fourth capacitor is attached Figure 3 C4 in the Figure 3The two series inductors L4 are loaded with a switching diode in the middle, and two identical structures are connected in parallel to form a two-series-inductor-loaded switching diode parallel structure.

[0067] The first strip structure and the second strip structure are equivalent to a fifth inductor.

[0068] Specifically, if Figure 3 As shown, the fifth inductor is attached Figure 3 L5 in.

[0069] The fourth capacitor and the control switch parallel structure connected in series are connected in parallel with the fifth inductor to form an energy switch layer equivalent circuit.

[0070] The energy switch layer equivalent circuit is connected in parallel with the absorbing layer equivalent circuit and the bandpass frequency selective surface layer equivalent circuit.

[0071] Specifically, the above-mentioned absorbing layer equivalent circuit and the bandpass frequency selective surface layer equivalent circuit are connected in parallel through the first dielectric layer and the air layer, and the bandpass frequency selective surface layer equivalent circuit and the energy switching layer front structure part equivalent circuit are connected in parallel through the second dielectric layer and the air layer.

[0072] From the equivalent circuit structure, it can be seen that when the second inductor L2 and the second capacitor C2 produce parallel resonance, the current does not form a path through the lumped resistor, so the incident wave can be directly transmitted to the bandpass frequency selective surface layer and the energy switch layer. At this time, the resonant frequency of the bandpass frequency selective surface layer is the same as the parallel resonant frequency of the second inductor L2 and the second capacitor C2. At the same time, when the diode is cut off, the energy switch layer also has the same parallel resonant frequency, so the electromagnetic wave can be transmitted through the entire structure. When the diode is turned on, the increase in inductance destroys the original resonance point, so the electromagnetic wave cannot be transmitted in this frequency band, thus forming a switching effect. Outside the resonant frequency, since the current will form a path through the lumped resistor, the energy is converted, achieving the effect of wave absorption. At the same time, the existence of the lumped resistor enables the structure to almost match the free space impedance in a wide bandwidth range, making the reflected wave very small, thereby achieving a broadband stealth effect.

[0073] From a holistic perspective, due to the generation of parallel resonance, and the subsequent bandpass frequency selective surface layer and energy switch layer also have wave-transmitting characteristics at this resonance point, the absorption-wave-transmitting-absorption effect can be achieved by adjusting the resonant frequencies of the interdigital structure, the bandpass frequency selective surface layer and the energy switch layer. By appropriately adjusting the structural parameters of each part to make the equivalent impedance of the metasurface match the impedance of free space, the overall structure can present low-reflection characteristics and achieve a better stealth effect.

[0074] The dielectric layer and the air layer can be regarded as a transmission line. Its electrical length is the transmission line length equivalent to the dielectric. The calculation formula is:

[0075]

[0076] Where: E is the electrical length, that is, the equivalent transmission line length, h is the dielectric thickness, and λ is the wavelength corresponding to the center frequency.

[0077] The impedance of the equivalent transmission line is:

[0078]

[0079] Where: Z is the impedance of the equivalent transmission line, Z0 is the impedance of free space, ε r is the relative dielectric constant of the medium.

[0080] The dielectric material of the absorbing layer and the bandpass frequency selection surface layer is Taconic TLY-5, the dielectric material of the energy switch layer is Fr-4, an air layer exists between the absorbing layer and the bandpass frequency selection surface layer, and an air layer exists between the bandpass frequency selection surface layer and the energy switch layer.

[0081] Specifically, the relative dielectric constant of Taconic TLY-5 is 2.2, and the electric loss tangent is 0.0009, and the relative dielectric constant of Fr-4 is 4.3, and the electric loss tangent is 0.025.

[0082] The period of the energy switch layer structure is half of the overall period.

[0083] Specifically, the overall structural period of the metasurface designed in the present invention is P, that is, the structure of the wave absorbing layer and the bandpass frequency selective surface layer is P, and the period of the energy switching layer is P / 2.

[0084] The energy switching layer period is half the overall period, meaning the unit length is half the overall unit length, and the unit area is one-quarter the overall unit area. Therefore, four energy switching layer units can be placed within one absorber unit and one bandpass frequency selective surface unit.

[0085] like Figure 2 An absorbing layer unit in Figure 4 A bandpass frequency selective surface layer unit in the corresponding Figure 5 The front structure of the four energy switch layer units and Figure 6 The back structure of the four energy switch layer units.

[0086] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. An ultra-wideband stealth surface structure with energy protection function, characterized in that: include: The wave absorbing layer is used to resonate with the incident electromagnetic wave to form a bandpass frequency and perform broadband absorption of electromagnetic waves outside the bandpass frequency; The absorbing layer includes a first dielectric plate, an interdigital structure is provided in the middle portion of the first dielectric plate, interdigital arm structures are provided at both ends of the interdigital structure, and the interdigital structure and the interdigital arm structures are connected via a lumped resistor; The equivalent circuit of the absorbing layer is as follows: The interdigital structure is equivalent to a parallel structure of a second capacitor and a second inductor; The lumped resistance is equivalent to the first resistance; The interdigital arm is equivalent to a series structure of a first capacitor and a first inductor; The parallel structure of the second capacitor and the second inductor, the first resistor, and the series structure of the first capacitor and the first inductor are sequentially connected in series to form an equivalent circuit of the absorbing layer; The bandpass frequency selective surface layer is used to select electromagnetic waves with the same bandpass frequency as the absorbing layer and to fully reflect electromagnetic waves in other frequency bands; The bandpass frequency selective surface layer comprises a second dielectric plate covered with a copper film, an I-shaped groove is provided in the middle portion of the second dielectric plate, and the I-shaped groove and the covering copper film form an I-shaped groove structure; The equivalent circuit of the I-shaped groove structure is specifically a third capacitor and a third inductor connected in parallel, and the third capacitor and the third inductor connected in parallel constitute an equivalent circuit of a bandpass frequency selective surface layer; the bandpass frequency selective surface layer equivalent circuit is connected in parallel with the equivalent circuit of the absorbing layer; The energy switch layer is used to adjust the resonant frequency of the structure to control the state of the overall wave transmission band, so as to select the energy of the incident electromagnetic waves within the bandpass frequency; The energy switch layer includes a third dielectric plate, a first ladder structure and a second ladder structure are symmetrically arranged on the front of the third dielectric plate, and a connecting portion of the first ladder structure and the second ladder structure is grooved in the middle and loaded with a switching diode; The back surface of the third dielectric plate is provided with a first strip structure and a second strip structure in parallel.

2. The ultra-wideband stealth surface structure with energy protection function according to claim 1, characterized in that: The equivalent circuit of the energy switching layer is as follows: The first ladder structure and the second ladder structure are equivalent to a fourth capacitor and a control switch connected in series in parallel; the control switch parallel structure is two identical fourth inductor-switching diode-fourth inductor structures connected in parallel, and the fourth inductor-switching diode-fourth inductor structure is a fourth inductor connected in series at each end of the switching diode; The first strip structure and the second strip structure are equivalent to a fifth inductor; The fourth capacitor and the control switch connected in series are connected in parallel with the fifth inductor to form an energy switch layer equivalent circuit; The energy switch layer equivalent circuit is connected in parallel with the absorbing layer equivalent circuit and the bandpass frequency selective surface layer equivalent circuit.

3. The ultra-wideband stealth surface structure with energy protection function according to claim 1, characterized in that: The period of the energy switch layer structure is half of the overall period.

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