A 1-bit transmission phase-modulated metasurface unit for millimeter waves

Abstract

The invention discloses a millimeter-wave oriented 1-bit transmission phase modulation metasurface unit, comprising an upper substrate and a lower substrate; the upper substrate has a top patch, and the lower substrate has a bottom patch; both patches are rectangular ring structures; the center of the top patch has a connection patch, and a PIN radio frequency switch is connected between the short side line of the top patch and the connection patch; the short side line of the bottom patch is connected to the rectangular patch; a metal stratum is provided between the two substrates, and a narrow gap with a through hole is provided on the stratum; one side line of the two patches is connected to the stratum through a first metal via hole, and the other side lines are connected to the stratum through a second metal via hole, and the connection patch is connected to the rectangular patch through a third metal via hole passing through the stratum through hole. The relative DC bias voltages of the via holes on both sides and the middle via hole are adjusted, and the two PIN radio frequency switches are controlled to be in opposite states, respectively, so that the metasurface unit presents two states, which is equivalent to the top patch being physically rotated 180°, thereby realizing 1-bit transmission phase modulation.

Description

Technical Field

[0001] The invention belongs to the field of radio frequency control of wireless communications and relates to a 1-bit transmission phase modulation metasurface unit for millimeter waves. Background Art

[0002] The ability of metasurface antennas to arbitrarily control electromagnetic waves has attracted widespread attention in many fields, especially in the fields of communications and radar. Compared with traditional parabolic antennas, metasurface antennas have a simple structure, flexible design, and can be electronically scanned, getting rid of the various disadvantages brought by mechanical servos. Although there is still a large gap in performance compared to phased array antennas, the simple feeding method and extremely low cost have made metasurface antennas widely used.

[0003] The metasurface antenna unit is one of the keys to designing a metasurface antenna. By rationally designing the unit structure, functions such as broadband, multi-frequency, and beam scanning can be realized. However, for the millimeter wave band of future 6G wireless communications, its wavelength is short and the loss is large. The existing transmissive metasurface is difficult to apply to high-frequency electromagnetic waves due to its large insertion loss. Summary of the invention

[0004] In view of the shortcomings of existing transmission metasurfaces, such as large insertion loss and difficulty in use for millimeter-wave transmission regulation, the present invention proposes a 1-bit transmission phase-modulation metasurface unit for millimeter waves.

[0005] The object of the present invention is achieved through the following technical solutions: A 1-bit transmission phase modulation metasurface unit for millimeter waves, comprising an upper substrate and a lower substrate;

[0006] The upper substrate has a top layer patch, and the lower substrate has a bottom layer patch;

[0007] The top patch and the bottom patch are both metal rectangular ring structures consisting of two long side lines and two short side lines;

[0008] A connecting patch is provided at the center of the top patch, and a first PIN radio frequency switch and a second PIN radio frequency switch are respectively connected between two short sides of the top patch and the connecting patch;

[0009] A rectangular patch facing the center is connected to the middle of the short side line of the bottom patch;

[0010] A metal layer is provided between the upper substrate and the lower substrate, and the metal layer has a narrow gap capable of transmitting millimeter waves and having a through hole;

[0011] One side long side line of the top patch and the bottom patch is connected to the metal layer through a first metal via, and the other side long side line is connected to the metal layer through a second metal via. The connecting patch of the top patch and the rectangular patch of the bottom patch are connected through a third metal via that passes through a gap through the metal layer.

[0012] Furthermore, the outer contour and the inner contour of the metal rectangular ring structure of the top patch and the bottom patch are the same.

[0013] Furthermore, the length and width of the upper substrate and the lower substrate are equal, denoted as W, satisfying Where λ is the wavelength of the millimeter wave.

[0014] Furthermore, the upper substrate and the lower substrate are both made of low-loss non-conductive dielectric material and have the same thickness.

[0015] Furthermore, the metal stratum is realized by copper plating of a polypropylene layer, and has a narrow gap without copper plating in the middle, the width of the narrow gap is equal to the width of the inner contour of the top patch and the bottom patch, and the length of the narrow gap is greater than or equal to the length of the inner contour of the top patch and the bottom patch.

[0016] Further, the positive pole / negative pole of the first PIN RF switch and the second PIN RF switch are oriented in the same direction, that is, the positive pole of the first PIN RF switch, the negative pole of the second PIN RF switch and the third metal via are electrically connected.

[0017] Furthermore, the diameters of the first metal via, the second metal via and the third metal via are the same.

[0018] Furthermore, the length and width of the metasurface unit are the same, W=2.43mm; the outer contour size of the top patch and the bottom patch is the same, the length is L1=1.52mm, and the width is W1=0.52mm; the inner contour size of the top patch and the bottom patch is the same, the length is L2=1.48mm, and the width is W2=0.33mm; the width of the rectangular patch is t=0.10mm; the thickness of the upper substrate and the lower substrate is the same, h1=0.50mm, the material is TLY-5, the phase dielectric constant is 2.2, and the loss tangent is 0.0009; the diameters of the three metal vias are d bias =0.10mm; the width of the narrow gap in the metal stratum is d h =0.33mm.

[0019] Furthermore, the first metal via and the second metal via are both grounded by the metal ground layer, the first metal via and the second metal via passing through the upper substrate are controlled by the same DC bias voltage U1, the third metal via is controlled by another DC bias voltage U2, and the third metal via is electrically connected to the first metal via and the second metal via passing through the lower substrate.

[0020] Furthermore, the 1-bit transmission phase modulation of the surface unit is achieved by controlling U1 and U2, specifically:

[0021] The voltage difference ΔU=|U1-U2| between the DC bias voltages U1 and U2 needs to be greater than the on-voltage of the PIN RF switch; by controlling the values ​​of U1 and U2, the first PIN RF switch and the second PIN RF switch are in opposite states respectively;

[0022] When one of the PIN RF switches is turned on, the circuit of the turned-on PIN RF switch is equivalent to the rectangular patch of the bottom patch, and the circuit of the turned-off PIN RF switch is equivalent to an open circuit;

[0023] When the conduction state of the two PIN RF switches changes, the top patch is equivalent to physically rotating 180°, so that the metasurface unit presents two states, thereby realizing 1-bit transmission phase modulation.

[0024] The beneficial effects of the present invention are as follows: the present invention provides a 1-bit transmission phase modulation metasurface unit for millimeter waves, which solves the problems of difficult transmission phase modulation and low transmission efficiency of existing high-frequency electromagnetic waves. The present invention designs a two-layer substrate structure, the upper substrate has a top-layer patch, and the lower substrate has a bottom-layer patch; both layers of patches are rectangular ring structures; the center of the top-layer patch has a connecting patch, and a PIN radio frequency switch is connected between the short side line of the top-layer patch and the connecting patch; the short side line of the bottom-layer patch is connected to the rectangular patch; there is a metal stratum between the two layers of substrates, and there is a narrow gap with a through hole on the stratum; one side line of the two layers of patches is connected to the stratum through the first metal via hole, and the other side line is connected to the stratum through the second metal via hole, and the connecting patch and the rectangular patch are connected through the third metal via hole through the stratum through hole. Adjust the relative DC bias voltage of the via holes on both sides and the middle via hole, control the two PIN radio frequency switches to be in opposite states, so that the metasurface unit presents two states, which is equivalent to the top patch physically rotating 180°, thereby realizing 1-bit transmission phase modulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. 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 paying creative labor.

[0026] Figure 1 It is a schematic structural diagram of a 1-bit transmission phase modulation metasurface unit for millimeter waves of the present invention;

[0027] Figure 2 It is a top view of a 1-bit transmission phase modulation metasurface unit facing millimeter waves of the present invention;

[0028] Figure 3 It is a bottom view of a 1-bit transmission phase modulation metasurface unit for millimeter waves of the present invention;

[0029] Figure 4 is a transmission amplitude curve of state 1 and state 2 in an embodiment of the present invention;

[0030] Figure 5 is a transmission amplitude difference curve between state 1 and state 2 in an embodiment of the present invention;

[0031] Figure 6 are transmission phase curves of state 1 and state 2 in an embodiment of the present invention;

[0032] Figure 7 is a transmission phase difference curve between state 1 and state 2 in an embodiment of the present invention;

[0033] In the figure: 1-top patch; 2-bottom patch; 3-first PIN RF switch; 4-second PIN RF switch; 5-first metal via; 6-second metal via; 7-third metal via; 8-upper substrate; 9-lower substrate; 10-metal ground layer. DETAILED DESCRIPTION

[0034] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0035] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0036] The embodiment of the present invention provides a 1-bit transmission phase modulation metasurface unit for millimeter waves, such as Figure 1-Figure 3 As shown, it includes a top patch 1, a bottom patch 2, a first PIN RF switch 3, a second PIN RF switch 4, a metal via, an upper substrate 8, a lower substrate 9 and other structures. The operating frequency of the metasurface unit is 55GHz to 65GHz. The spatial position relationship of different structures of the metasurface unit is:

[0037] The upper surface of the upper substrate 8 has a top patch 1 , and the lower surface of the lower substrate 9 has a bottom patch 2 .

[0038] The top patch 1 and the bottom patch 2 have the same outer contour, both of which are metal rectangular ring structures composed of two long sides and two short sides. The inner contours of the metal rectangular ring structures are the same. This symmetrical structure of the inner and outer contours helps to achieve a more ideal 1-bit phase modulation function and helps to reduce the adverse effects of the DC bias voltage. The center of the top patch 1 has a connecting patch, and the first PIN RF switch 3 and the second PIN RF switch 4 are respectively connected between the two short sides of the top patch 1 and the connecting patch. The middle of the short side of the bottom patch 2 is connected to a rectangular patch toward the center.

[0039] A metal layer 10 is provided between the lower surface of the upper substrate 8 and the upper surface of the lower substrate 9 , and the metal layer 10 has a narrow gap capable of transmitting millimeter waves and having a through hole.

[0040] The middle of one side long side line of the top patch 1 and the bottom patch 2 is connected to the metal layer 10 through the first metal via 5, and the middle of the other side long side line is connected to the metal layer 10 through the second metal via 6. The central connecting patch of the top patch 1 is connected to the rectangular patch of the bottom patch 2 through the third metal via 7 that passes through the gap through the metal layer.

[0041] Furthermore, in order to maximize the beam energy in a specified direction, the length and width of the upper substrate 8 and the lower substrate 9 are equal, and the length and width are denoted as W, and the following conditions are satisfied:

[0042]

[0043] Here, λ is the wavelength of the millimeter wave. In this embodiment, the wavelength of the millimeter wave with a center frequency of 60 GHz is λ=5 mm, and the length and width W of the upper substrate 8 and the lower substrate 9 are W=2.43 mm, which meets the above conditions.

[0044] Furthermore, the metal layer 10 is realized by copper plating of a polypropylene (pp) layer, and has a narrow gap without copper plating in the middle, the width of the narrow gap is equal to the width of the inner contour of the top patch 1 and the bottom patch 2, and the length of the narrow gap is greater than or equal to the length of the inner contour of the top patch 1 and the bottom patch 2, so that the millimeter wave of the incident metasurface unit can effectively pass through the upper substrate 8 and the lower substrate 9. At the same time, the microwave transmission line equivalent to the top patch 1 and the bottom patch 2 is used to change the phase of the millimeter wave output wave.

[0045] Furthermore, the positive / negative poles of the first PIN RF switch 3 and the second PIN RF switch 4 are oriented in the same direction, that is, the positive pole of the first PIN RF switch 3, the negative pole of the second PIN RF switch 4 and the third metal via 7 are electrically connected; in this embodiment, the first PIN RF switch 3 and the second PIN RF switch 4 adopt MACOM's MA4GP907.

[0046] Furthermore, the diameters of the three metal vias are the same; the first metal via 5 and the second metal via 6 are both grounded by the metal ground layer 10, the first metal via 5 and the second metal via 6 passing through the upper substrate 8 are controlled by the same DC bias voltage U1, and the third metal via 7 is controlled by another DC bias voltage U2, and the third metal via 7 is electrically connected to the first metal via 5 and the second metal via 6 passing through the lower substrate 9.

[0047] Furthermore, the upper substrate 8 and the lower substrate 9 are both made of low-loss non-conductive dielectric material with the same thickness. In this embodiment, the thickness h1=0.50 mm, the material is TLY-5, the relative dielectric constant is 2.2, and the loss tangent is 0.0009.

[0048] The 1-bit transmission phase modulation of the transmission phase modulation metasurface unit designed in the present invention is achieved by controlling U1 and U2, specifically:

[0049] The voltage difference ΔU=|U1-U2| between the DC bias voltages U1 and U2 needs to be greater than the turn-on voltage of the PIN RF switch.

[0050] When U1>U2, the first PIN RF switch 3 is turned on, which is equivalent to a small resistor, and the branch where it is located is in a low-resistance state. The second PIN RF switch 4 is turned off, which is equivalent to a large capacitor, and the branch where it is located is in a high-resistance state; when U1<U2, the first PIN RF switch 3 is turned off, which is equivalent to a large capacitor, and the branch where it is located is in a high-resistance state. The second PIN RF switch 4 is turned on, which is equivalent to a small resistor, and the branch where it is located is in a low-resistance state; that is, by controlling the size of U1 and U2, the first PIN RF switch 3 and the second PIN RF switch 4 are in opposite states respectively.

[0051] When one of the PIN RF switches is turned on, the circuit of the turned-on PIN RF switch is equivalent to the rectangular patch of the bottom patch 2, and the circuit of the turned-off PIN RF switch is equivalent to an open circuit.

[0052] When the conduction state of the two PIN RF switches changes, the top-layer patch 1 is equivalent to physically rotating 180°, so that the metasurface unit presents two states. In these two states, the amplitude of the transmitted wave is approximately equal and the phase difference is approximately 180°, thereby realizing 1-bit transmission phase modulation.

[0053] In one embodiment, the size constraints of different structures are as follows: the length and width of the metasurface unit are the same, W=2.43mm; the outer contours of the top patch 1 and the bottom patch 2 are the same, with a length of L1=1.52mm and a width of W1=0.52mm; the inner contours of the top patch 1 and the bottom patch 2 are the same, with a length of L2=1.48mm and a width of W2=0.33mm; the width of the rectangular patch is t=0.10mm; the thickness of the upper substrate 8 and the lower substrate 9 is the same, h1=0.50mm, the material is TLY-5, the phase dielectric constant is 2.2, and the loss tangent is 0.0009; the size of the three metal vias is the same, with a diameter of d bias =0.10mm; the width of the narrow gap of the metal layer 10 is d h =0.33mm.

[0054] In this embodiment, state 1 is that the first PIN RF switch 3 is turned on and the second PIN RF switch 4 is turned off; state 2 is that the first PIN RF switch 3 is turned off and the second PIN RF switch 4 is turned on. Figure 4 It is the transmission amplitude curve of state 1 and state 2 of the present invention. It can be seen from the figure that the transmission amplitude loss of state 1 and state 2 is about -4dB near the center frequency of 60GHz, indicating that the designed metasurface unit has a small insertion loss for millimeter waves and a high transmission efficiency. Figure 5 It is the transmission amplitude difference curve of state 1 and state 2 of the present invention. It can be seen from the figure that when the center frequency of the millimeter wave is around 60GHz, the transmission amplitude difference is less than 2dB, which means that the amplitude of the transmitted wave is approximately equal in these two states.

[0055] Figure 6 is the transmission phase curve of state 1 and state 2 of the present invention, Figure 7 It is the transmission phase difference curve of the present invention between state 1 and state 2. It can be seen from the figure that when the center frequency of the millimeter wave is around 60GHz, the phase difference is approximately 180°, which shows that the metasurface unit designed by the present invention can achieve 1-bit transmission phase modulation in a relatively ideal way.

[0056] The above description is merely a preferred embodiment of one or more embodiments of the present specification and is not intended to limit one or more embodiments of the present specification. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present specification shall be included in the scope of protection of one or more embodiments of the present specification.

Claims

1. A 1-bit transmission phase-modulation metasurface unit for millimeter waves, characterized in that: The operating frequency of the metasurface unit is 55 GHz to 65 GHz. The metasurface unit includes an upper substrate and a lower substrate. The length and width of the upper substrate and the lower substrate are equal and are recorded as W. Where λ is the wavelength of the millimeter wave; The upper substrate has a top layer patch, and the lower substrate has a bottom layer patch; The top patch and the bottom patch have the same outer contour, both of which are metal rectangular ring structures composed of two long sides and two short sides, and the inner contours of the metal rectangular ring structures are the same; A connecting patch is provided at the center of the top patch, and a first PIN radio frequency switch and a second PIN radio frequency switch are respectively connected between two short sides of the top patch and the connecting patch; A rectangular patch facing the center is connected to the middle of the short side line of the bottom patch; There is a metal stratum between the upper substrate and the lower substrate, and the metal stratum is realized by copper plating of a polypropylene layer. A narrow non-copper-plated slot with a through hole that can transmit millimeter waves is provided in the middle of the metal stratum. The width of the narrow slot is equal to the width of the inner contour of the top patch and the bottom patch, and the length of the narrow slot is greater than or equal to the length of the inner contour of the top patch and the bottom patch, so that the millimeter wave incident on the metasurface unit can effectively pass through the upper substrate and the lower substrate, and at the same time, the phase of the millimeter wave outgoing wave is changed by using the microwave transmission line equivalent to the top patch and the bottom patch; One side long side line of the top patch and the bottom patch is connected to the metal layer through a first metal via, and the other side long side line is connected to the metal layer through a second metal via. The connection patch of the top patch and the rectangular patch of the bottom patch are connected through a third metal via that passes through a gap through the metal layer. The first metal via and the second metal via are both grounded by a metal ground layer, the first metal via and the second metal via penetrating the upper substrate are controlled by the same DC bias voltage U1, the third metal via is controlled by another DC bias voltage U2, and the third metal via is electrically connected to the first metal via and the second metal via penetrating the lower substrate; The positive / negative poles of the first PIN RF switch and the second PIN RF switch are oriented in the same direction, that is, the positive pole of the first PIN RF switch, the negative pole of the second PIN RF switch and the third metal via are electrically connected; the diameters of the first metal via, the second metal via and the third metal via are the same; The 1-bit transmission phase modulation of the metasurface unit is achieved by controlling U1 and U2, specifically: The voltage difference ΔU=|U1-U2| between the DC bias voltages U1 and U2 needs to be greater than the on-voltage of the PIN RF switch; by controlling the values ​​of U1 and U2, the first PIN RF switch and the second PIN RF switch are in opposite states respectively; When one of the PIN RF switches is turned on, the circuit of the turned-on PIN RF switch is equivalent to the rectangular patch of the bottom patch, and the circuit of the turned-off PIN RF switch is equivalent to an open circuit; When the conduction state of the two PIN RF switches changes, the top patch is equivalent to physically rotating 180°, so that the metasurface unit presents two states, thereby realizing 1-bit transmission phase modulation.

2. The 1-bit transmission phase-modulated metasurface unit for millimeter waves according to claim 1, characterized in that: The upper substrate and the lower substrate are both made of low-loss non-conductive dielectric material and have the same thickness.

3. The 1-bit transmission phase-modulated metasurface unit for millimeter waves according to claim 1, characterized in that: The length and width of the metasurface unit are the same, W=2.43mm; the outer contour size of the top patch and the bottom patch is the same, the length is L1=1.52mm, and the width is W1=0.52mm; the inner contour size of the top patch and the bottom patch is the same, the length is L2=1.48mm, and the width is W2=0.33mm; the width of the rectangular patch is t=0.10mm; the thickness of the upper substrate and the lower substrate is the same, h1=0.50mm, the material is TLY-5, the phase dielectric constant is 2.2, and the loss tangent is 0.0009; the diameters of the three metal vias are d bias =0.10mm; the width of the narrow gap in the metal stratum is d h =0.33mm.

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