Wave absorption structure based on phase modulation surface

Abstract

This invention discloses a wave-absorbing structure based on a phase-modulated surface, comprising a base plate layer and a dielectric plate layer arranged from bottom to top. The upper surface of the dielectric plate layer is provided with wave-absorbing units. Each wave-absorbing unit includes at least one annular metal patch and at least two semi-annular metal patches. The semi-annular metal patches are located on both sides of the annular metal patch, and the middle of each semi-annular metal patch is connected to the annular metal patch via a first diode. Second diodes are located at both ends of each semi-annular metal patch, at the edges of the dielectric plate layer. By setting wave-absorbing units on the dielectric plate layer and a base plate layer on its bottom end face, incident waves entering this structure are reflected by the base plate layer and the wave-absorbing units, with the reflected wave signals having a 180° phase difference. This increases the bandwidth occupancy percentage of the wave-absorbing structure within a certain frequency band.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing technology, and in particular to an absorbing structure based on a phase modulation surface. Background Technology

[0002] Frequency-selective radomes need to achieve high transmittance within the operating frequency band and high cutoff performance outside the operating frequency band, thereby reflecting electromagnetic waves incident on the target in other directions. This enables the stealth performance of a single-station radar, but is ineffective against dual-station or multi-station radar network systems. Chambers proposed a novel planar design that, by controlling one or more conductive surfaces, allows the radar to switch between complete transmission and complete reflection between incident electromagnetic waves, thus achieving so-called absorption of electromagnetic waves.

[0003] In recent years, with the advancement of technology, researchers have developed a double-bowtie structure, which has a width of 15mm, a length of 15.5mm, and a thickness of 5mm. This structure can occupy 22% of the bandwidth in the 16-20GHz frequency band. A three-square-ring nested structure has also been developed, in which varactor diodes are interconnected in the middle. This structure has a thickness of 4mm and can occupy 40% of the bandwidth in the 2.15-3.23GHz frequency band. Furthermore, a mushroom-shaped artificial magnetic conductor structure has been developed, which can occupy 30% of the bandwidth in the 3.05-4.15GHz frequency band. In summary, existing absorbing structures have a relatively low bandwidth in the 6.1–13.7 GHz incident wave frequency band. In addition, the thickness of the aforementioned absorbing structures is not less than 4 mm, which is relatively thick, resulting in a heavy weight of the entire absorbing mechanism, which is not conducive to its application in antenna systems. Summary of the Invention

[0004] The main objective of this invention is to provide an absorbing structure based on a phase modulation surface, which solves the problem mentioned in the background art that the absorbing mechanism is too thick and has a relatively low bandwidth in a specific frequency band.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The microwave absorbing structure based on the phase modulation surface includes a bottom plate layer and a dielectric plate layer arranged from bottom to top, and the upper surface of the dielectric plate layer is provided with microwave absorbing units. The absorbing unit includes at least one annular metal patch and at least two semi-annular metal patches. The semi-annular metal patches are located on both sides of the annular metal patch. The middle part of the semi-annular metal patch is connected to the annular metal patch through a first diode. Second diodes are provided at both ends of the semi-annular metal patch, and the second diodes are located at the edge of the dielectric substrate layer.

[0006] Furthermore, the height of the dielectric substrate layer is 3.4-3.8 mm, preferably 3.6 mm, and the length and width are both 12.0-12.5 mm, preferably 12.2 mm.

[0007] Furthermore, the dielectric substrate layer is selected from FR-4 epoxy glass cloth laminate or FR-4 epoxy resin board, and the relative permittivity is 4.2-4.6, preferably 4.4.

[0008] Furthermore, the inner diameter of the annular metal patch and the semi-annular metal patch is 2.2-2.7 mm, preferably 3 mm, the outer diameter is 2.7-3.2 mm, preferably 2.5 mm, and the thickness is no more than 0.05 mm.

[0009] Furthermore, the annular metal patch and the semi-annular metal patch are made of copper sheets.

[0010] Furthermore, the base plate is made of copper and has a thickness of less than 0.15 mm.

[0011] Furthermore, the length of the first diode is 0.4-1.2 mm, preferably 1.2 mm, and the width is 0.2-0.9 mm, preferably 0.8 mm; The length of the second diode is half the length of the first diode, and the width of the second diode is equal to the width of the first diode.

[0012] Compared with the prior art, the present invention has the following beneficial effects: This invention features an absorbing unit on a dielectric substrate and a base plate on its bottom surface. When an incident wave enters the structure, it is reflected by the base plate and the absorbing unit, with the reflected wave signals having a 180° phase difference. During the absorption process, the resistance of the first and second diodes in the absorbing structure is controlled over a period of time, thereby increasing the bandwidth occupancy percentage of the 6.1–13.7 GHz frequency band, raising the bandwidth occupancy to 71%, and reducing the amplitude by 10 dB. Furthermore, compared to other absorbing structures, this structure is thinner overall, resulting in a smaller volume and lower weight. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of an absorbing structure based on a phase modulation surface. Figure 2 This is a top view schematic diagram of an absorbing structure based on a phase modulation surface; Figure 3 This is a schematic diagram of the circuit connection of the phase modulation surface-based absorbing structure in the simulation software. Figure 4The reflection coefficient curve and phase curve of the phase-modulated surface-based absorbing structure are shown in the simulation. Figure 5 The phase difference diagram shows the phase difference of the absorbing structure based on the phase modulation surface as a function of frequency under different impedances in the simulation. Figure 6 This is a diagram showing the electric field distribution of a diode in a phase-modulated surface-based absorbing structure under different resistances.

[0014] In the diagram: 1. Base plate layer; 2. Dielectric plate layer; 3. Absorbing unit; 30. Annular metal patch; 4. Semi-annular metal patch; 5. Second diode. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] See Figure 1 and Figure 2 This invention discloses a wave-absorbing structure based on a phase modulation surface. The wave-absorbing device includes a base plate layer 1, which is made of copper plate with a thickness of less than 0.15 mm. A dielectric plate layer 2 is disposed on the upper surface of the base plate layer 1. The height of the dielectric plate layer 2 is 3.4-3.8 mm, and the length and width are both 12.0-12.5 mm. The dielectric plate layer 2 is made of FR-4 epoxy glass cloth laminate or FR-4 epoxy resin board with a relative permittivity of 4.2-4.6. A wave-absorbing unit 3 is disposed on the upper surface of the dielectric plate layer 2. The wave-absorbing unit 3 is located at the center of the upper end face of the dielectric plate layer 2, and the front and rear ends of the wave-absorbing unit 3 are parallel to the front and rear end faces of the dielectric plate layer 2.

[0017] See Figure 1 and Figure 2The absorbing unit 3 includes at least one annular metal patch 30 and at least two semi-annular metal patches 31. The annular metal patch 30 is disposed at the center of the upper end face of the dielectric substrate 2 and is symmetrically arranged about the transverse center line of the upper end face of the dielectric substrate 2. The semi-annular metal patches 31 are located on both sides of the annular metal patch 30. The middle part of the semi-annular metal patch 31 is connected to the annular metal patch 30 through a first diode 4. Second diodes 5 are disposed at both ends of the semi-annular metal patch 31, and the other end of the second diode 5 is flush with the end face of the dielectric substrate 2. In this invention, a power supply is connected to the first diode 4 and the second diode 5. The first diode 4 and the second diode 5 form a certain magnetic field, which changes the phase of the incident wave. Then, the incident wave on the phase modulation surface is reflected by the base plate layer 1 and the absorbing unit 3. During the absorption process, the resistance of the first diode 4 and the second diode 5 in the absorbing structure is controlled to change over a period of time. The change pattern is: R=0 (complete reflection), R=∞ (complete transparency); R=∞ (complete transparency), R=0 (complete reflection). This is repeated so that the phase difference between the emitted wave signal on the base plate layer 1 and the absorbing unit 3 is 180°, thereby increasing the bandwidth occupancy percentage of the absorbing structure in the incident 6.1-13.7GHz frequency band.

[0018] Furthermore, the inner diameter of the annular metal patch 30 and the semi-annular metal patch 31 is 2.2-2.7 mm, the outer diameter is 2.7-3.2 mm, and the thickness is no more than 0.05 mm; The first diode 4 has a length of 0.4–1.2 mm and a width of 0.2–0.9 mm; The length of the second diode 5 is half the length of the first diode 4, and the width of the second diode 5 is equal to the width of the first diode 4.

[0019] This invention provides a structural embodiment in which the dimensions of the dielectric substrate layer 2, the base plate layer 1, the annular metal patch 30, the semi-annular metal patch 31, the first diode 4, and the second diode 5 are selected as follows; The dielectric layer 2 is a cuboid with a height h1 = 3.6 mm, and a length and width of 12.2 mm. The dielectric layer 2 can be selected with a relative permittivity ε. r =4.4 FR-4 epoxy resin board.

[0020] The inner diameter of the ring in the absorbing patch 3 is selected as r=2.5mm, the outer diameter is selected as R=3mm, and the thickness is selected as h2=0.05mm; the material of the annular metal patch 30 and the semi-annular metal patch 31 is copper sheet.

[0021] The length and width of the base plate layer 1 are equal to the length and width of the dielectric plate layer 2, and the thickness is selected as h3=0.15mm. The material of the base plate layer 1 is also copper sheet.

[0022] The first diode 4 and the second diode 5 are ordinary diodes. The dimensions of the first diode 4 are selected as follows: length h4 = 1.2 mm and width w4 = 0.8 mm. The dimensions of the second diode 5 are selected as follows: length h5 = 0.6 mm and width w5 = 0.8 mm.

[0023] The technical effects of the present invention will be further explained below with reference to simulation experiments: 1. Simulation Model: The absorbing structure in the embodiment was modeled in the commercial simulation software HFSS15.0, and the transmission coefficient and reflection coefficient of the structure were simulated and calculated.

[0024] 2. Simulation content: 2.1 Electromagnetic simulation of the above simulation model was performed using the commercial simulation software HFSS15.0. The circuit diagram of this simulation software can be found here. Figure 3 The parameter results are obtained.

[0025] 2.2 Using the data processing system of the commercial simulation software HFSS15.0, the data results are as follows: Figure 4 .

[0026] 3. Simulation results: See Figure 4 The figure reflects the reflection coefficient curve and phase curve of the absorbing structure based on the phase modulation surface in the simulation. Through the reflection absorption curve S11 of the first diode 4 and the second diode 5 under low impedance and high impedance conditions, and the phase curve S11 of the first diode 4 and the second diode 5 under low impedance (impedance value less than 1 ohm) and high impedance (impedance value greater than 10000 ohms), it can be seen that the incident waves on the base plate layer 1 and the absorbing unit 3 are totally reflected under different impedance conditions. However, by changing the impedance values ​​of the first diode 4 and the second diode 5 in the absorbing unit 3, a certain phase difference can be made between the base plate layer 1 and the absorbing unit 3. That is to say, by adjusting the impedance value of the diode, the percentage of bandwidth occupied by the present invention in a certain frequency band can be increased, thereby achieving stealth in the required frequency band.

[0027] See Figure 5This figure shows the phase difference of the absorbing structure based on the phase modulation surface under different impedances as a function of frequency in the simulation. In the phase range of 6.1-13.7 GHz, the reflection coefficient phase curve S11 accounts for 71% of the total frequency bandwidth in the frequency bandwidth region of 143°-217°, and the amplitude is reduced by 10 dB. This shows that the present invention can effectively increase the percentage of bandwidth occupied by the absorbing structure in the incident wave 6.1-13.7 GHz frequency band. At the same time, the present invention has a small and lightweight structure. Compared with the existing absorbing structures, the thickness and volume are smaller, thereby reducing the weight and facilitating its use in antenna systems.

[0028] Figure 6 The figure shows the electromagnetic field distribution of a diode in a phase-modulated surface-based absorbing structure under different resistance conditions. It can be seen from the figure that the electromagnetic field generated by the diode changes under different resistance conditions. This changes the phase of the incident wave, allowing the absorbing structure to switch between two states: completely transparent (R=∞) and completely reflected (R=0), thus achieving stealth of the absorbing structure in the required frequency band.

[0029] The simulation results show that the phase modulation surface-based absorbing structure proposed in this invention has a wide bandwidth in the incident wave frequency band of 6.1-13.7 GHz. At the same time, the entire device has the advantages of being lightweight, thin, and easy to process, and can be widely used in the absorbing structure of antenna systems.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A microwave absorbing structure based on a phase modulation surface, characterized in that, It includes a bottom plate layer (1) and a dielectric plate layer (2) arranged from bottom to top, and the upper surface of the dielectric plate layer (2) is provided with a wave-absorbing unit (3); The absorbing unit (3) includes at least one annular metal patch (30) and at least two semi-annular metal patches (31). The semi-annular metal patches (31) are located on both sides of the annular metal patch (30). The middle part of the semi-annular metal patch (31) is connected to the annular metal patch (30) through a first diode (4). Second diodes (5) are provided at both ends of the semi-annular metal patch (31). The second diodes (5) are located at the edge of the dielectric substrate layer (2). The first diode (4) and the second diodes (5) are externally connected to a power supply. The magnetic field is used to change the phase of the incident wave. The incident wave on the phase modulation surface is reflected by the base plate layer (1) and the absorbing unit (3). During the absorption process, the resistance of the first diode (4) and the second diode (5) in the absorbing structure is controlled. The change rule is: R=0, R=∞; R=∞, R=0 is repeated so that the reflected wave signal on the base plate layer (1) and the absorbing unit (3) is 180° out of phase. This is used to increase the bandwidth occupancy percentage of the absorbing structure in the incident 6.1-13.7GHz frequency band. Where R=0 represents perfect reflection, and R=∞ represents perfect transparency; The dielectric layer (2) is an FR-4 epoxy glass cloth laminate or an FR-4 epoxy resin board, and its relative permittivity is 4.2-4.

6.

2. The absorbing structure based on a phase modulation surface according to claim 1, characterized in that, The height of the dielectric substrate layer (2) is 3.4-3.8 mm, and the length and width are both 12.0-12.5 mm.

3. The absorbing structure based on a phase modulation surface according to claim 1, characterized in that, The inner diameter of the annular metal patch (30) and the semi-annular metal patch (31) is 2.2-2.7 mm, the outer diameter is 2.7-3.2 mm, and the thickness is no more than 0.05 mm.

4. The absorbing structure based on a phase modulation surface according to claim 1, characterized in that, The annular metal patch (30) and the semi-annular metal patch (31) are made of copper sheets.

5. The absorbing structure based on a phase modulation surface according to claim 1, characterized in that, The base plate (1) is made of copper plate with a thickness of less than 0.15 mm.

6. The absorbing structure based on a phase modulation surface according to claim 1, characterized in that, The first diode (4) has a length of 0.4-1.2 mm and a width of 0.2-0.9 mm; The length of the second diode (5) is half the length of the first diode (4), and the width of the second diode (5) is equal to the width of the first diode (4).

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