Broadband low-scattering reflection surface based on back-loaded active microstrip network

Abstract

The invention discloses a broadband low-scattering reflection surface based on a back-loaded active microstrip network, which integrates an antenna unit with the back-loaded active microstrip network to control the response of the low-scattering reflection surface to incoming waves. Wherein the antenna unit sequentially comprises a top dielectric matching layer, a dipole patch, a first dielectric substrate, a coupling capacitor metal disc, a second dielectric substrate, a metal floor and a third dielectric substrate from top to bottom; the back-loaded active microstrip network is arranged below the third dielectric substrate; after receiving an incident wave, the antenna unit transmits the incident wave into the back-loaded active microstrip network, and after network processing, the incident wave is radiated to a free space through the antenna unit; the back-loaded active microstrip network realizes phase control of TE polarized reflected waves by adjusting the on-off state of the PIN tube, and realizes absorption of TM polarized incoming waves by loading a resistor in the middle of the short-circuit microstrip line. According to the invention, low profile and miniaturization are ensured, and wave absorbing and active scattering regulation and control functions are realized at the same time.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic metasurfaces, specifically relating to a broadband low-scattering reflection surface based on a back-mounted active microstrip network. Background Technology

[0002] With the rapid development of modern radar detection technology, reducing the probability of friendly equipment being detected by enemy radar over a wide bandwidth has attracted widespread attention. Radar Cross Section (RCS) is a measure of a target's ability to scatter electromagnetic waves in the direction of radar reception; it is characterized as the ratio of the power scattered by the target in the direction of radar reception to the power density incident on the target. Reducing the target's RCS can decrease the power scattered by the target and lower the probability of the target being detected. Therefore, how to reduce the RCS over a wide bandwidth to achieve low detectability has become a key technical challenge.

[0003] Currently, there are two main types of traditional methods for reducing RCS. The first is to absorb incoming wave energy using the principle of wave absorption. This includes designing the surface of an object as an absorbing structure and coating the surface with absorbing materials, essentially using the principle of loss to dissipate the energy of the incident wave. The second is to effectively control electromagnetic scattering using metamaterials or metasurfaces. This involves using phase modulation to achieve phase cancellation between scattered waves, thus achieving a low-scattering effect. Metasurfaces are widely used in the realization of low-scattering devices due to their outstanding advantages such as ultrathinness, conformal design, low loss, and ease of fabrication. However, most traditional low-scattering metasurfaces operate in a passive state. Once designed, their operating characteristics cannot be dynamically controlled, making them unsuitable for variable environments. Furthermore, most traditional low-scattering metasurfaces have a single low-scattering function, using only one of the wave absorption or scattering modulation principles, and have a narrow operating bandwidth, making them unable to adapt to the changing needs of devices.

[0004] Therefore, due to the needs of practical applications, there is an urgent need to explore a design method for a broadband low-scattering reflection surface that is actively dynamically controlled and multifunctionally integrated. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a broadband low-scattering reflection surface based on a back-mounted active microstrip network, which, while ensuring low profile and miniaturization, also has the functions of wave absorption and active scattering control.

[0006] Technical Solution: To achieve the above-mentioned objectives, this invention provides a broadband low-scattering reflection surface based on a back-mounted active microstrip network, comprising an antenna element and a back-mounted active microstrip network. The antenna element, from top to bottom, comprises a top dielectric matching layer, a dipole patch, a first dielectric substrate, a coupling capacitor metal disk, a second dielectric substrate, a metal ground plane, and a third dielectric substrate. The back-mounted active microstrip network is disposed below the third dielectric substrate. After receiving an incident wave, the antenna element transmits it to the back-mounted active microstrip network. After network processing, the wave is radiated into free space through the antenna element. The back-mounted active microstrip network achieves phase control of the TE-polarized reflected wave by adjusting the on / off state of the PIN diode, and absorbs the TM-polarized incoming wave by loading a resistor in the middle of the short-circuited microstrip line.

[0007] Preferably, the four adjacent dipoles in the dipole patch form a cross-coupled structure. For each polarization of the antenna element, the dipole is unbalancedly fed by a pair of internal metal vias. One dipole arm is directly grounded through an internal metal via, and the other dipole arm is excited by another internal metal via.

[0008] Preferably, the back-mounted active microstrip network includes a TE polarization network and a TM polarization network, wherein the TE polarization network is used for broadband scattering modulation of TE polarized waves, and the TM polarization network is used for broadband absorption of TM polarized waves.

[0009] Preferably, the TE polarization network of the back-mounted active microstrip network includes a short-circuited microstrip line with a PIN diode and an open-circuited stub connected in series with the short-circuited microstrip line; the back-mounted active microstrip network controls the phase of the TE polarization reflected wave by controlling the on / off state of the PIN diode; wherein, the reflected wave corresponding to the PIN on state and the PIN off state has a 1-bit phase difference, ensuring that the phase of the reflected wave in the two states cancels out.

[0010] Preferably, the short-circuited microstrip line with a PIN diode in the TE polarization network consists of two first microstrip lines and a second microstrip line with different widths, and a PIN diode in the middle; one end of the first microstrip line is connected to the metal ground plane through a metal via, and the other end is connected to the PIN diode; one end of the second microstrip line is connected to the antenna element through a metal via, and the other end is connected to the PIN diode.

[0011] Preferably, when the PIN diode is in the on state, it is equivalent to an inductor and a resistor connected in series; when the PIN diode is in the off state, it is equivalent to an inductor and a capacitor connected in series.

[0012] Preferably, the TM polarization network of the back-mounted active microstrip network includes a short-circuited microstrip line with a resistor. One end of the short-circuited microstrip line is connected to a metal ground plane through a metal via, and the other end is connected to an antenna element through a metal via. The back-mounted active microstrip network achieves loss of incoming waves through the applied resistor.

[0013] Preferably, the broadband low-scattering reflective surface is an array structure, and the back-mounted active microstrip network is encoded in a checkerboard pattern, with the cell adjacent to the cell encoded as 0 being encoded as 1.

[0014] Preferably, the broadband low-scattering reflective surface is an array structure, and the antenna elements form a crisscrossing hollow structure.

[0015] Beneficial effects: Compared with the prior art, the significant advantages of this invention are:

[0016] (1) The designed broadband low-scattering reflective surface integrates the antenna element with the back-mounted active microstrip network. It utilizes the broadband characteristics of the antenna element and controls the back-mounted active microstrip network to realize the broadband response of the broadband low-scattering reflective surface to the incoming wave.

[0017] (2) The designed broadband low-scattering reflective surface breaks through the previous single-function low scattering, integrates the two mechanisms of wave absorption and scattering control, and realizes multi-functional dual-polarization low scattering.

[0018] (3) The designed broadband low-scattering reflection surface has the characteristics of low profile, miniaturization and high integration. It can achieve dynamic control of the scattering of a certain polarized electromagnetic wave by controlling the on and off of a single PIN tube. Attached Figure Description

[0019] Figure 1 This is a three-dimensional exploded view of a unit in an embodiment of the present invention.

[0020] Figure 2 This is a top view of a unit according to an embodiment of the present invention.

[0021] Figure 3 This is a side view of a unit according to an embodiment of the present invention.

[0022] Figure 4 This is a bottom view of a unit according to an embodiment of the present invention.

[0023] Figure 5 This is an active VSWR curve of the dipole antenna element used in the embodiments of the present invention.

[0024] Figure 6 The following are simulation results of the back-mounted active microstrip network in the embodiments of the present invention, wherein: (a) TE polarization reflection coefficient curve, (b) TE polarization reflection phase curve, and (c) TM polarization reflection coefficient curve.

[0025] Figure 7 In this embodiment of the invention, the TE polarized microstrip network is configured according to 10... A diagram illustrating the 1-bit encoding corresponding to the 10-grid pattern.

[0026] Figure 8 To implement the broadband low-scattering reflective surface unit of the present invention according to 10 The array diagram after assembling 10 chessboard grid codes.

[0027] Figure 9 To make the broadband low-scattering reflective surface of the present invention undergo 10 The diagram shows the RCS reduction of the corresponding equally sized metal plates after 10 arrays, where: (a) 10 (b) RCS reduction of 10-array TE polarization relative to a metal plate of the same size. RCS reduction of 10-array TM polarization relative to a metal plate of the same size. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and modifications without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0029] It should be noted that relational terms such as "first" and "second" in this text are used merely 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.

[0030] Figure 1 This illustration shows a unit structure diagram of a broadband low-scattering reflection surface based on a back-mounted active microstrip network provided by an embodiment of the present invention. Figure 1As shown, the broadband low-scattering reflective surface structure integrates an antenna element with a back-mounted active microstrip network 13 to control the low-scattering reflective surface's response to incoming waves. The antenna element structure, from top to bottom, includes a top dielectric matching layer 1, a dipole patch 2, a first dielectric substrate 3, a coupling capacitor metal disk 4, a second dielectric substrate 5, a metal ground plane 6, a third dielectric substrate 7, and internal vias 8, 9, 10, 11, and 12. The antenna element is located above the third dielectric substrate 7, and the back-mounted active microstrip network 13 is located below it. After receiving the incident wave, the antenna element transmits it to the back-mounted active microstrip network 13. After network processing, the wave is radiated into free space through the antenna element. The back-mounted active microstrip network 13 achieves phase control of the TE-polarized reflected wave by adjusting the on / off state of the PIN diode, and absorbs the TM-polarized incoming wave by loading a resistor in the middle of the short-circuited microstrip line.

[0031] In practical applications, the antenna unit can be designed independently, consisting of a top dielectric matching layer 1, a dipole patch 2, a first dielectric substrate 3, a coupling capacitor metal disk 4, a second dielectric substrate 5, a metal ground plane 6, a third dielectric substrate 7, and internal vias 8, 9, 10, 11, and 12, from top to bottom.

[0032] In this embodiment, the dielectric matching layer, the first dielectric substrate, and the second dielectric substrate are all made of dielectric substrates with a relative permittivity of 2.2, and the third dielectric substrate is made of dielectric substrates with a relative permittivity of 3.0.

[0033] In this embodiment, a cross-coupled structure is formed between four adjacent dipoles in the dipole patch 2. This structure provides the necessary capacitive coupling to counteract the inductive effect of the ground plane at low frequencies and broaden the operating bandwidth of the antenna. For each polarization of the antenna element, the dipole is unbalancedly fed by a pair of internal metal vias (8, 9 or 10, 11). One dipole arm is directly grounded through one internal metal via (8 or 10), and the other dipole arm is excited by the other internal metal via (9 or 11).

[0034] In this embodiment, the antenna element is directly connected to the back-mounted active microstrip network through an internal metal via, and the antenna element transmits electromagnetic waves to the back-mounted active microstrip network through the internal metal via.

[0035] In this embodiment, the coupling capacitor disk 4 can enhance the capacitive coupling between dipoles, effectively counteract the inductive effect of the ground at low frequencies, and further reduce the minimum operating bandwidth of the antenna element.

[0036] In this embodiment, the TE polarization network of the back-mounted active microstrip network 13 is a short-circuited microstrip line with a PIN diode, connected in series with an open-circuit stub to achieve wideband impedance matching. The short-circuited microstrip line with the PIN diode consists of two first microstrip lines and a second microstrip line with different widths, and a PIN diode in between. One end of the first microstrip line is connected to a metal ground plane through a metal via, and the other end is connected to the PIN diode. One end of the second microstrip line is connected to the antenna element through a metal via, and the other end is connected to the PIN diode. The TE polarization network can receive and process the electromagnetic waves received by the antenna element. By controlling the on / off state of the PIN diode, the microstrip network can achieve phase control of the TE polarized reflected wave. The reflected wave corresponding to the PIN on state and the PIN off state has a 1-bit phase difference, ensuring that the phases of the reflected waves in the two states cancel each other out, achieving a wideband low-scattering effect. The switching on and off of the PIN diode can be controlled at the unit level by an active DC bias line laid above the third dielectric substrate 7. The negative terminal of the PIN diode is directly connected to the first microstrip line, which is equivalent to being grounded. The switching on and off of the PIN diode can be controlled by adding an active DC bias line to the positive terminal of the PIN diode.

[0037] In this embodiment, the TM polarization network of the back-mounted active microstrip network 13 is a short-circuited microstrip line with a characteristic impedance of 50Ω. One end of the short-circuited microstrip line is connected to a metal ground plane through a metal via, and the other end is connected to an antenna element through a metal via. It can receive and process the electromagnetic waves received by the antenna element. A 50Ω resistor is loaded in the middle of the microstrip short line to achieve loss of incoming waves, thereby achieving broadband wave absorption.

[0038] Specifically, the TE polarization network enables broadband scattering control of TE polarized waves, and the TM polarization network enables broadband absorption of TM polarized waves, thereby achieving dual-polarization broadband low scattering.

[0039] In practical applications, the PIN diode model can be MADP-000907-14020P. When the PIN diode is in the conducting state, it is equivalent to a 30pH inductor connected in series with a 7.8Ω resistor; when the PIN diode is in the off state, it is equivalent to a 30pH inductor connected in series with a 0.025pF capacitor.

[0040] This invention integrates an upper-layer broadband antenna element with a lower-layer back-mounted active microstrip network. While ensuring the broadband characteristics of the upper-layer antenna element, it proposes a broadband low-scattering reflection surface based on the lower-layer back-mounted active microstrip network through design and optimization. The effects of this invention are illustrated below with a specific application example.

[0041] like Figure 2As shown, the broadband low-scattering reflection surface unit structure provided in this embodiment has a period p=10mm, and the period of the top dielectric matching layer is also 10mm.

[0042] like Figure 3 The side view of the broadband low-scattering reflective surface shown, with the thickness of the top dielectric matching layer. The thickness of the first dielectric substrate is The thickness of the second dielectric substrate The thickness of the third dielectric substrate is The overall thickness is 0.14. ( It has a low profile and operates at a minimum frequency of 6 GHz (vacuum wavelength).

[0043] like Figure 4 As shown, the back-loaded active microstrip network can be divided into two polarizations. The TE polarization network shown is a short-circuited microstrip line with an open-circuit stub connected in series to achieve wideband impedance matching. The first segment of the short-circuited microstrip line is... The second segment width Width of the open branch When the electromagnetic wave received by the antenna element enters the TE polarization network, the TE polarization network can actively process the electromagnetic wave. By controlling the on / off state of the PIN diode, the phase control of the TE polarization reflected wave can be achieved. Specifically, the reflected wave corresponding to the PIN on state and the PIN off state has a 1-bit phase difference, ensuring that the phases of the reflected waves in the two states cancel each other out, achieving a broadband low-scattering effect. The TM polarization network shown is a short-circuited microstrip line with a characteristic impedance of 50Ω, and a 50Ω resistor is loaded in the middle of the microstrip short-circuit line. When the electromagnetic wave received by the antenna element enters the TM polarization network, the TM polarization network can dissipate the electromagnetic wave over a wide range, achieving a broadband low-scattering effect.

[0044] In practical applications, the first step is to design the upper-layer dipole antenna element and obtain its active VSWR curve, such as... Figure 5 As shown, within the broadband range of 5.8-14.3 GHz, the active standing wave ratio of the dipole antenna is below 1.5, exhibiting good broadband radiation performance.

[0045] Next, the back-mounted active microstrip network was designed, and the overall structure of the broadband low-scattering reflective surface was simulated in CST software. The reflection coefficients for the two states of TE polarization were obtained as follows: Figure 6 As shown in (a), the phase difference of the reflected waves corresponding to the two states of TE polarization is as follows: Figure 6As shown in (b), by controlling the on / off state of the PIN diode, the reflected waves corresponding to the PIN on-state and PIN off-state can achieve a phase difference of 180°±30° in the range of 7.75-14.25GHz, and from... Figure 6 As can be seen from (a), the amplitudes of the reflected waves in the two states are similar, meaning that low scattering of TE-polarized reflected waves over a wide bandwidth can be achieved through 1-bit encoding. The reflection coefficient of TM-polarized waves is as follows... Figure 6 As shown in (c), the TM polarization reflection coefficient is below -10dB in the range of 5.58-14.54GHz, which can also achieve the low scattering effect of TM reflected waves in the broadband range.

[0046] Furthermore, the designed broadband low-scattering reflection surface is configured according to 10 Encode using a 10-grid layout, 10 A diagram illustrating the 1-bit encoding corresponding to the 10-grid pattern is shown below. Figure 7 As shown, Figure 8 To implement the broadband low-scattering reflective surface unit of the present invention according to 10 An array diagram after 10 checkerboard grids are encoded with 1 bit.

[0047] Finally, the broadband low-scattering reflective surface unit of the present invention is arranged according to 10 The array, after being 1-bit encoded using a 10-grid pattern, underwent full-wave simulation in CST. Simultaneously, a metal plate of the same size as the array was also subjected to full-wave simulation, and the 10... RCS reduction of a 10-grid array relative to a metal plate of the same size. Figure 9 (a) shows 10 The reduction in TE polarization of a 10-grid array relative to the RCS of a metal plate of the same size. Figure 9 (b) shows 10 The reduction in RCS of the TM polarization of the 10-grid array compared to the same-sized metal plate shows that both polarizations achieve a reduction of more than 10 dB over the broadband range, demonstrating good broadband low scattering performance.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A broadband low-scattering reflection surface based on a back-mounted active microstrip network, characterized in that, The device includes an antenna element and a back-mounted active microstrip network. The antenna element, from top to bottom, includes a top dielectric matching layer, a dipole patch, a first dielectric substrate, a coupling capacitor metal disk, a second dielectric substrate, a metal ground plane, and a third dielectric substrate. The back-mounted active microstrip network is located below the third dielectric substrate. After receiving an incident wave, the antenna element transmits it to the back-mounted active microstrip network. After processing by the network, the wave is radiated into free space through the antenna element. The back-mounted active microstrip network achieves phase control of the TE-polarized reflected wave by adjusting the on / off state of the PIN diode and absorbs the TM-polarized incoming wave by loading a resistor in the middle of the short-circuited microstrip line.

2. The broadband low-scattering reflection surface based on a back-mounted active microstrip network according to claim 1, characterized in that, The four adjacent dipoles in the dipole patch form a cross-coupled structure. For each polarization of the antenna element, the dipole is unbalancedly fed by a pair of internal metal vias. One dipole arm is directly grounded through an internal metal via, and the other dipole arm is excited by another internal metal via.

3. The broadband low-scattering reflection surface based on a back-mounted active microstrip network according to claim 1, characterized in that, The antenna element is directly connected to the back-mounted active microstrip network through an internal metal via, and the antenna element transmits electromagnetic waves to the back-mounted active microstrip network through the internal metal via.

4. The broadband low-scattering reflection surface based on a back-mounted active microstrip network according to claim 1, characterized in that, The back-mounted active microstrip network includes a TE polarization network and a TM polarization network. The TE polarization network is used for broadband scattering modulation of TE polarized waves, and the TM polarization network is used for broadband absorption of TM polarized waves.

5. The broadband low-scattering reflection surface based on a back-mounted active microstrip network according to claim 4, characterized in that, The TE polarization network of the back-mounted active microstrip network includes a short-circuited microstrip line with a PIN diode and an open-circuited stub connected in series with the short-circuited microstrip line. The back-mounted active microstrip network controls the phase of the TE polarization reflected wave by controlling the on / off state of the PIN diode. The reflected wave corresponding to the PIN on state and the PIN off state has a 1-bit phase difference, ensuring that the phases of the reflected waves in the two states cancel each other out.

6. The broadband low-scattering reflection surface based on a back-mounted active microstrip network according to claim 5, characterized in that, The short-circuit microstrip line with a PIN diode in the TE polarization network consists of two first microstrip lines and a second microstrip line with different widths, and a PIN diode in the middle; one end of the first microstrip line is connected to the metal ground plane through a metal via, and the other end is connected to the PIN diode; one end of the second microstrip line is connected to the antenna element through a metal via, and the other end is connected to the PIN diode.

7. The broadband low-scattering reflection surface based on a back-mounted active microstrip network according to claim 5, characterized in that, When the PIN diode is in the ON state, it is equivalent to an inductor and a resistor connected in series; when the PIN diode is in the OFF state, it is equivalent to an inductor and a capacitor connected in series.

8. The broadband low-scattering reflection surface based on a back-mounted active microstrip network according to claim 4, characterized in that, The TM polarization network of the back-mounted active microstrip network includes a short-circuited microstrip line with a resistor. One end of the short-circuited microstrip line is connected to a metal ground plane through a metal via, and the other end is connected to an antenna element through a metal via. The back-mounted active microstrip network achieves loss of incoming waves through the applied resistor.

9. The broadband low-scattering reflection surface based on a back-mounted active microstrip network according to claim 1, characterized in that, The broadband low-scattering reflective surface is an array structure, and the back-mounted active microstrip network is coded in a checkerboard pattern, with the unit adjacent to the unit coded as 0 being coded as 1; the antenna unit forms a crisscrossing hollow structure.

10. The broadband low-scattering reflection surface based on a back-mounted active microstrip network according to claim 1, characterized in that, The broadband low-scattering reflective surface is an array structure, and the antenna elements form a crisscrossing hollow structure.

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