An electromagnetic absorption and penetration integrated structure

Abstract

The present invention discloses an electromagnetic absorption-penetration integrated structure, which is divided into an independently designed transmission path and an absorption path. The transmission path is composed of a receiving antenna, a transmitting antenna and a closed transmission line, and the absorption path is composed of a band-stop frequency selection surface and an absorbing material. The receiving antenna and the transmitting antenna are connected by a transmission line and are respectively placed at both ends of the transmission line. The band-stop frequency selection surface and the absorbing material are placed between the receiving antenna and the transmitting antenna, and the transmission line passes through the band-stop frequency selection surface and the absorbing material. The band-stop frequency selection surface is placed on one side of the receiving antenna, and the absorbing material is placed on one side of the absorbing antenna. There is an air gap between the band-stop frequency selection surface and the absorbing material. The transmission path and the absorption path of the present invention are independently designed. During operation, the transmission path and the absorption path will not affect each other, and the technical effect of in-band absorption through out-of-band absorption can also be achieved. The present invention can be widely used in the field of electromagnetic stealth.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic stealth, and in particular to an electromagnetic absorption and penetration integrated structure. Background Art

[0002] Frequency selective surfaces (FS) have excellent properties in frequency filtering, phase tuning, beam steering, and electromagnetic stealth, and therefore have broad application prospects in radar and satellite communication systems. However, since bandpass FSS are usually fully reflective outside the band, they are not suitable for stealth applications in multi-station radars. Therefore, frequency selective absorptive and penetrating integrated structures that have both out-of-band absorption and in-band transmission functions are gaining increasing attention. However, existing planar absorptive and penetrating integrated structures consist of a FSS and an impedance layer with a parallel resonator. The impedance layer structure controls both the absorption and transmission performance of the overall structure, and the two properties restrict each other.

[0003] Therefore, in order to solve the problem in the prior art that the design of an electromagnetic absorption and penetration integrated structure is mutually restricted by the performance of the absorption path and the transmission path, an electromagnetic absorption and penetration integrated structure in which the absorption path and the transmission path can be independently designed has important research significance. Summary of the Invention

[0004] In view of this, an embodiment of the present invention provides an electromagnetic absorption and penetration integrated structure in which both the absorption path and the transmission path can be independently designed.

[0005] One aspect of an embodiment of the present invention provides an electromagnetic absorption and penetration integrated structure, comprising: a transmission path and an absorption path;

[0006] The transmission path includes: a receiving antenna, a transmitting antenna and a closed transmission line;

[0007] The absorption path includes: a band-stop frequency selective surface and an absorbing material;

[0008] The receiving antenna and the transmitting antenna are connected via the transmission line and are respectively placed at both ends of the transmission line. The band-stop frequency selective surface and the absorbing material are placed between the receiving antenna and the transmitting antenna. The transmission line passes through the band-stop frequency selective surface and the absorbing material. The band-stop frequency selective surface is placed on a side close to the receiving antenna, and the absorbing material is placed on a side close to the transmitting antenna. There is an air gap between the band-stop frequency selective surface and the absorbing material.

[0009] The receiving antenna is used to capture the directly incident target in-band electromagnetic waves and the target in-band electromagnetic waves reflected by the band-stop frequency selective surface, and convert the target in-band electromagnetic waves into guided electromagnetic waves;

[0010] The transmission line is used to transmit the guided electromagnetic wave;

[0011] The transmitting antenna is used to radiate the guided electromagnetic wave;

[0012] The absorbing material is used to absorb out-of-band electromagnetic waves except the target in-band electromagnetic waves.

[0013] Preferably, the receiving antenna is an electrically small folded dipole antenna with a wide beam.

[0014] Preferably, the impedance bandwidth of the transmitting antenna covers the impedance bandwidth of the receiving antenna.

[0015] Preferably, the transmission line consists of an inner metal layer, an outer metal layer and a transmission medium between the inner and outer metal layers.

[0016] Preferably, the inner metal layer and the transmission medium are used to transmit the guided electromagnetic waves.

[0017] Preferably, the outer metal layer is electrically connected to the absorption path.

[0018] Preferably, the band-stop frequency selective surface is a lossless band-stop frequency selective surface, which is used to totally reflect electromagnetic waves within a target band and is transparent to electromagnetic waves outside the band.

[0019] The electromagnetic absorption-penetration integrated structure of the present invention is divided into independently designed transmission paths and absorption paths. The transmission path consists of a receiving antenna, a transmitting antenna, and a closed transmission line, while the absorption path consists of a band-stop frequency selective surface and an absorbing material. The receiving antenna and the transmitting antenna are connected by a transmission line and are placed at either end of the transmission line. The band-stop frequency selective surface and the absorbing material are placed between the receiving antenna and the transmitting antenna, and the transmission line passes through the band-stop frequency selective surface and the absorbing material. The band-stop frequency selective surface is placed on one side of the receiving antenna, and the absorbing material is placed on the side closest to the transmitting antenna. There is an air gap between the band-stop frequency selective surface and the absorbing material. The present invention independently designs the transmission path and the absorption path. When the receiving antenna captures the directly incident target in-band electromagnetic wave and the target in-band electromagnetic wave reflected by the band-stop frequency selective surface, the target in-band electromagnetic wave can be converted into a guided electromagnetic wave; then the transmission line transmits the guided electromagnetic wave to the transmitting antenna, and then the transmitting antenna can radiate the guided electromagnetic wave. Since the transmission path is independent of the absorption path, the transmission path can completely absorb the target in-band electromagnetic wave and is not affected by the absorption path; in addition, the absorbing material can absorb out-of-band electromagnetic waves in addition to the target in-band electromagnetic wave. Similarly, the absorption path is independent of the transmission path, and can completely absorb the out-of-band electromagnetic wave without being affected by the transmission path. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A structural framework diagram of an electromagnetic absorption and penetration integrated structure provided by an embodiment of the present invention;

[0022] Figure 2 A structural diagram of a periodic array of a narrow-band electromagnetic absorption and penetration integrated structure designed based on the electromagnetic absorption and penetration integrated structure of the present invention provided in an embodiment of the present invention;

[0023] Figure 3 A structural diagram of a periodic unit of a narrow-band absorbent-transmitter integrated structure provided by an embodiment of the present invention;

[0024] Figure 4 A cross-sectional view of a narrow-band absorbent-permeable integrated structure provided by an embodiment of the present invention;

[0025] Figure 5 This is an E-plane far-field diagram of the middle unit of a 7×7 receiving antenna array provided by an embodiment of the present invention at 5.6 GHz;

[0026] Figure 6 A directional pattern of a 7×7 receiving antenna array provided in an embodiment of the present invention;

[0027] Figure 7 A parameter diagram of the reflection coefficient (S11) and transmission coefficient (S21) of transverse electric polarization (TE) and transverse magnetic polarization (TM) waves provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] Reference Figure 1 , an embodiment of the present invention provides an electromagnetic absorption and penetration integrated structure, which specifically includes two parts: a transmission path and an absorption path.

[0030] Specifically, the transmission path may include: a receiving antenna, a transmitting antenna, and a closed transmission line. The absorption path may include: a band-stop frequency selective surface and an absorbing material.

[0031] First, the connection relationship between the various elements in the electromagnetic absorption and penetration integrated structure of the present invention is explained, which may specifically include the following: the receiving antenna and the transmitting antenna are connected through a transmission line and are respectively placed at both ends of the transmission line, the band-stop frequency selective surface and the absorbing material are placed between the receiving antenna and the transmitting antenna, and the transmission line passes through the band-stop frequency selective surface and the absorbing material, the band-stop frequency selective surface is placed on the side close to the receiving antenna, the absorbing material is placed on the side close to the transmitting antenna, and there is an air gap between the band-stop frequency selective surface and the absorbing material.

[0032] Next, the functions of the various components of the integrated electromagnetic absorption and penetration structure of the present invention are described. Specifically, the receiving antenna can be used to capture directly incident in-band electromagnetic waves and in-band electromagnetic waves reflected by the band-stop frequency selective surface, and convert the in-band electromagnetic waves into guided electromagnetic waves. The frequency of the in-band electromagnetic waves can be determined by the receiving antenna, so the in-band electromagnetic waves can serve as target in-band electromagnetic waves.

[0033] In addition, the transmission line can be used to transmit guided electromagnetic waves, the transmitting antenna can be used to radiate guided electromagnetic waves, and the absorbing material is used to absorb out-of-band electromagnetic waves other than the target in-band electromagnetic waves. The out-of-band electromagnetic waves can include out-of-band low-frequency electromagnetic waves and out-of-band high-frequency electromagnetic waves.

[0034] The working principle of the electromagnetic absorption and penetration integrated structure of the present invention may include: the receiving antenna captures the directly incident in-band electromagnetic waves and the in-band electromagnetic waves reflected by the band-stop frequency selective surface, and then converts the in-band electromagnetic waves into guided electromagnetic waves. The guided electromagnetic waves are transmitted to the transmitting antenna through a closed transmission line, and finally the transmitting antenna radiates the guided electromagnetic waves into free space to generate a transmission response.

[0035] Furthermore, the transmission line of the present invention is described.

[0036] Specifically, the transmission path is independent of the absorption path. A closed transmission line can consist of two metal layers, inner and outer, with a transmission medium between them. The inner metal layer and the transmission medium can be used to transmit guided electromagnetic waves. Furthermore, the outer metal layer can be electrically connected to the absorption path, effectively acting as a ground for the inner metal layer. Therefore, the guided electromagnetic waves transmitted along the transmission path can be shielded by the outer metal layer of the closed transmission line, making them independent of the absorption path.

[0037] To address the angular stability issues of existing integrated absorber-transmitter structures, the present invention employs a wide-beam antenna for the receiving antenna. Since the transmission response primarily depends on the directivity of the receiving antenna, a wide-beam antenna can capture electromagnetic waves incident at wider angles than a narrow-beam antenna. Therefore, the present invention employs an electrically small folded dipole antenna with a wide beam as the receiving antenna. Furthermore, to achieve bandpass frequency selectivity with low insertion loss, the transmitting antenna's impedance bandwidth can overlap that of a narrowband receiving antenna.

[0038] In order to achieve the technical effect of absorbing out-of-band and passing in-band electromagnetic waves, the band-stop frequency selective surface of the electromagnetic absorption and penetration integrated structure of the present invention can be a lossless band-stop frequency selective surface.

[0039] Next, we will use specific examples to illustrate the actual application process of the present invention. Figure 2 、 Figure 3 and Figure 4 , Figure 2 A periodic array of a narrow-band electromagnetic absorption and penetration integrated structure designed based on the electromagnetic absorption and penetration integrated structure of the present invention is shown. Figure 3 A periodic unit of the narrow-band absorbent-through integrated structure is shown. Figure 4 A cross-sectional view of the narrow-band absorbent-through integrated structure is shown.

[0040] Periodic array of narrow-band absorption and penetration integrated structure Figure 2 As shown, it is an N*N array composed of several 1-one unit structures. In an optional implementation, N can be greater than 7.

[0041] right Figure 3 A periodic unit of the narrow-band absorbent-penetrating integrated structure is described as follows:

[0042] 1-A periodic unit consists of 2-absorption paths ( Figure 3 ) and 3-transmission paths ( Figure 4 ) composition. Period dimension p = 25 mm.

[0043] Next, the absorption path and the transmission path are described respectively. Specifically, the 2-absorption path may include:

[0044] The 2-absorption path consists of a 21-band-stop frequency selective surface and an absorbing material separated by a gap of air. The thickness of the air gap is ha1 = 9.05 mm.

[0045] The 21-band-stop frequency selective surface is a "M"-shaped ring structure with a central stripe-shaped gap. The entire structure is etched from a copper conductor and printed on a 212-base substrate. The 212-base substrate has a thickness of ta1 = 0.8mm. The metal arms of the "M"-shaped frequency selective surface are la2 = 5.3mm long and wa4 = 1mm wide, with a metal edge width of wa5 = 0.3mm. The bottom angle of the butterfly-shaped metal patch is θa = 47 degrees.

[0046] The absorbing material consists of a 22-layer impedance layer and a 23-layer metal ground layer separated by air and a substrate. The distance between the impedance layer and the metal ground layer is ha2 = 5mm. The 22-layer impedance layer is composed of a 221-layer orthogonal butterfly dipole metal with four identical 222-layer lumped resistors soldered in the middle. The metal substrate is a 212-layer substrate. The 221-layer butterfly dipole has a width of la1 = 6mm and a distance from the substrate edge of wa2 = 0.85mm. The metal arm connecting the resistor has a width of wa2 = 0.8mm, and the square gap in the middle has a width of wa3 = 1.9mm. The value of the 222-layer lumped resistor is RL = 120 ohms.

[0047] The 212-substrate material used is Rogers RO4003C substrate (dielectric constant εr = 3.55, loss tangent tanδ = 0.0027).

[0048] 3- Transmission paths may include:

[0049] like Figure 4 As shown, the transmission path 3 consists of three parts: 31 - receiving antenna, 32 - closed transmission line, and 33 - transmitting antenna. The periodic unit size p = 25 mm.

[0050] 31-The receiving antenna is a cross-shaped symmetrical dipole antenna printed on the substrate, and its four arms are formed by folding the same dipole antenna, such as Figure 3 The metal arm of the receiving antenna has a thickness of wt2 = 0.3 mm, a folding width of lt3 = 2.7 mm, and a folding interval of lt4 = 2 mm; the substrate has a length of lt5 = 10 mm and a thickness of gt1 = 1.216 mm.

[0051] The 32-closed transmission line consists of two parts: a 321-parallel two-wire transmission line and a 322-substrate integrated coaxial line. The 32-closed transmission line allows the conducted signal to pass through the absorption path without leakage.

[0052] The 321-parallel transmission line consists of four identical, high-impedance, thin conductors printed on a substrate. It is used to match the input impedance of the receiving antenna. The parallel two-wire transmission line has a length of lt1 = 11.5 mm and a width of wt1 = 1 mm. The spacing between a pair of parallel two-wires within a unit structure is gt2 = 3.7 mm.

[0053] The 322-substrate integrated coaxial cable consists of an inner metal layer and an outer metal layer. The inner metal layer is a 3221-wide metal patch with a characteristic impedance close to 50 ohms, giving the 322-substrate integrated coaxial cable an optimal combination of power handling and attenuation constant. The inner metal layer of the substrate-integrated coaxial cable has a length of lt2 = 13.75 mm and a width of wt3 = 2 mm.

[0054] The outer metal layer of the 322-substrate integrated coaxial cable is surrounded by 3222-metal vias and a 3223-external conductor metal sheet. This outer metal layer shields and absorbs interference from the transmission path and reduces radiation loss of the transmitted signal. The outer metal layer of the substrate-integrated coaxial cable has a length of lt2 = 13.75 mm and a width of wt4 = 5.018 mm.

[0055] 33- Transmitting Antenna: The transmitting antenna needs a wider working bandwidth to receive waves from the closed transmission line and radiate them into free space with minimum insertion loss. Figure 3 As shown, the 33-mm transmitting antenna is an orthogonal dipole structure, with four arms consisting of wide patches printed on a 212-mm substrate. The inner metal layer of the 322-mm substrate integrated coaxial line is extended and securely fixed to the 33-mm transmitting antenna's feed point, ensuring it can receive transmitted waves. The 33-mm transmitting antenna and the absorbing material share a 23-mm metal ground plane, enhancing the antenna's radiation efficiency. The transmitting antenna substrate has a thickness of tw1 = 0.8 mm, a height of hw1 = 6.6 mm above the metal ground plane, and a metal arm length of lw1 = 7.2 mm and a width of ww1 = 3 mm. Opposing metal arms are spaced 4.9 mm apart by gw1.

[0056] The substrate printed on the receiving antenna and the closed transmission line uses a 0.02mm thick Rogers RO4450F adhesive layer (dielectric constant εr = 3.54, loss tangent tanδ = 0.004).

[0057] Next, let's discuss the beamwidth of the receiving antenna:

[0058] To further investigate the beamwidth of the proposed receiving antenna, a 7×7 array is constructed and the active far-field pattern of the middle unit is simulated. Figure 5 Its E-plane radiation pattern at 5.6 GHz is shown, and it can be observed that its 3 dB beamwidth covers 121.2 degrees, indicating that the proposed receiving antenna integrated with a closed transmission line is a wide-beam antenna.

[0059] The proposed 7×7 array and its directional pattern are shown as follows: Figure 6 (a), (b) and (c), where Figure 6 (a) is the array pattern at normal incidence. Figure 6 (b) is the directivity diagram at -60 degrees incidence. Figure 6 (c) is the directional pattern from -60 degrees to 60 degrees. When the phase difference ξ of a group of antenna pairs along the X direction is 0 degrees, the main beam direction is at 0 degrees. When each group of antenna pairs along the X direction has λ0 is the wavelength corresponding to the center frequency, f0=5.6GHz,

[0060] When the phase difference is 100 nm (with a periodic structure size of p = 25 mm), the array's main beam points towards -54 degrees, and both patterns exhibit high gain and low sidelobes. In particular, since transmission and reception are reciprocal problems, the receiving antenna array exhibits excellent wide-angle scanning performance, demonstrating its ability to effectively receive electromagnetic waves incident at wide angles.

[0061] Figure 7 The radiation pattern shown in (c) shows that the receiving antenna array scan angle covers a range of ±54 degrees. Here, the scanning principle of the phased array antenna is applied for the first time to solve the high-angle incidence problem of the integrated absorption and penetration structure.

[0062] The simulation results are as follows: The polarization independence and angle stability are verified by simulation. The reflection coefficient (S 11 ) and transmission coefficient (S 21 ),like Figure 7 shown. Figure 7 (a) is the S parameter diagram of the narrowband absorber-transmitter structure under TE and TM polarization and normal incidence. The simulation results show that under TE and TM polarization, the absorber-transmitter structure has a low reflection coefficient (S) in the range of 4-9.45 GHz (81%). 11 ≤-10dB), -3dB transmission band (S 21 ≥-3dB) is 5.47-5.95GHz (8.41%), among which the minimum insertion loss reaches 0.59dB at 5.7GHz. Figure 7 The TE polarization results shown in (b) show that S 21 ≥-3dB coverage 5.47-5.74GHz (4.8%), angular stability of 60 degrees; Figure 7 The TM polarization results shown in (c) show that S 21 ≥-3dB covers 5.46-5.78GHz (5.7%) with an incident angle of 0 to 30 degrees. In all simulation results, the out-of-band suppression of the transmission response in the double-sideband is roughly below -10dB.

[0063] In some optional embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the present invention is provided in an exemplary manner for the purpose of providing a more comprehensive understanding of the technology. The disclosed method is not limited to the operation and logic flow presented herein. Optional embodiments are contemplated in which the order of the various operations is changed and the sub-operations described as a part of a larger operation are performed independently.

[0064] Furthermore, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise indicated, one or more of the functions and / or features described may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in separate physical devices or software modules. It will also be understood that a detailed discussion of the actual implementation of each module is not necessary for understanding the present invention. More specifically, given the properties, functions, and internal relationships of the various functional modules in the devices disclosed herein, the actual implementation of the module will be understood within the ordinary skill of an engineer. Therefore, a person skilled in the art using ordinary skill will be able to implement the present invention set forth in the claims without undue experimentation. It will also be understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the present invention, which is determined by the full scope of the appended claims and their equivalents.

Claims

1. An electromagnetic absorption and penetration integrated structure, characterized in that: include: Transmission path and absorption path; The transmission path includes: a receiving antenna, a transmitting antenna and a closed transmission line; The absorption path includes: a band-stop frequency selective surface and an absorbing material; The receiving antenna and the transmitting antenna are connected via the transmission line and are respectively placed at both ends of the transmission line. The band-stop frequency selective surface and the absorbing material are placed between the receiving antenna and the transmitting antenna. The transmission line passes through the band-stop frequency selective surface and the absorbing material. The band-stop frequency selective surface is placed on a side close to the receiving antenna, and the absorbing material is placed on a side close to the transmitting antenna. There is an air gap between the band-stop frequency selective surface and the absorbing material. The receiving antenna is used to capture the directly incident target in-band electromagnetic waves and the target in-band electromagnetic waves reflected by the band-stop frequency selective surface, and convert the target in-band electromagnetic waves into guided electromagnetic waves; The transmission line is used to transmit the guided electromagnetic wave; The transmitting antenna is used to radiate the guided electromagnetic wave; The absorbing material is used to absorb out-of-band electromagnetic waves except the target in-band electromagnetic waves.

2. The electromagnetic absorption and penetration integrated structure according to claim 1, characterized in that: The receiving antenna is an electrically small folded dipole antenna with a wide beam.

3. The electromagnetic absorption and penetration integrated structure according to claim 1, characterized in that: The impedance bandwidth of the transmitting antenna covers the impedance bandwidth of the receiving antenna.

4. The electromagnetic absorption and penetration integrated structure according to claim 1, characterized in that: The transmission line consists of an inner metal layer, an outer metal layer and a transmission medium between the inner and outer metal layers.

5. The electromagnetic absorption and penetration integrated structure according to claim 4, characterized in that: The inner metal layer and the transmission medium are used to transmit the guided electromagnetic wave.

6. The electromagnetic absorption and penetration integrated structure according to claim 4, characterized in that: The outer metal layer is electrically connected to the absorption path.

7. The electromagnetic absorption and penetration integrated structure according to claim 1, characterized in that: The band-stop frequency selective surface is a lossless band-stop frequency selective surface, which is used to fully reflect electromagnetic waves within a target band and is transparent to electromagnetic waves outside the band.

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