1-bit standing wave metasurface programmable antenna

Abstract

The invention discloses a 1-bit standing wave metasurface programmable antenna, and belongs to the technical field of antennas. The antenna comprises a U-shaped groove waveguide and a PCB (Printed Circuit Board), the empty slot surface of the U-shaped slot waveguide is placed upwards, and the PCB is located on the upper surface of the U-shaped slot waveguide and comprises a flexible dielectric substrate, an upper metal layer located on the upper surface of the flexible dielectric substrate and a lower metal layer located on the lower surface of the flexible dielectric substrate. The standing wave metasurface programmable antenna has the advantages of high efficiency, cost reduction, far and near field beam regulation and control capability, small size and circuit complexity reduction, and breaks through the technical difficulty that planar 1-bit standing wave beam scanning has directional diagram normal symmetry. A new waveguide slot-PIN diode metasurface unit is designed, only one PIN diode is adopted, 1-bit phase and amplitude control over the slot metasurface unit is achieved, and cost and branch control circuit design complexity are reduced.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology, and specifically relates to a 1-bit standing wave metasurface programmable antenna. Background Art

[0002] Indoor distributed communication systems are key infrastructure for modern mobile communication networks. In the communication environment of indoor distributed communication systems, antennas must be capable of high-efficiency, wide-angle beam scanning. While existing phased array technology can achieve high-precision beam steering, its high component costs hinder large-scale civilian deployment. Current leaky-wave metasurface antennas can achieve wide-angle scanning through coding, but they all require a large number of PIN diodes and have low efficiency, primarily due to their use of a leaky-wave transmission mode. Furthermore, existing metasurface antenna units require at least two PIN diodes, significantly increasing the cost of the array and making DC control design more difficult. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a 1-bit standing wave metasurface programmable antenna with high efficiency, low cost, small size, reduced circuit design difficulty, and the ability to flexibly and dynamically switch between far-field beam scanning and near-field beam focusing.

[0004] The technical problem proposed by the present invention is solved as follows:

[0005] A 1-bit standing wave metasurface programmable antenna includes a U-shaped slot waveguide 1 and a PCB board 2. The U-shaped slot waveguide 1 is placed with the empty slot facing upward, and the curvature coefficient is less than a set threshold.

[0006] The PCB board 2 is located on the upper surface of the U-shaped slot waveguide 1, and includes a flexible dielectric substrate, an upper metal layer located on the upper surface of the flexible dielectric substrate, and a lower metal layer located on the lower surface of the flexible dielectric substrate;

[0007] The lower metal layer is a rectangular metal strip that completely covers the empty slot of the U-slot waveguide 1. Several groups of radiating slot pairs are periodically formed on the metal strip along the propagation direction of the U-slot waveguide 1. Each group of radiating slot pairs includes two identical radiating slots 3 that are symmetrical about the long axis of the metal strip. Different groups of radiating slot pairs have different lengths and spacings between the radiating slots 3.

[0008] The flexible dielectric substrate has a first metallized through hole 4 on the inner side of each radiation slot 3 and a second metallized through hole 9 on the outer side. The first metallized through hole 4 and the second metallized through hole 9 are symmetrical about the radiation slot 3.

[0009] The upper metal layer includes a resistor pad 5, a rectangular microstrip branch 6, a stepped microstrip branch 8, a metal ring 10, a metal wire pad 7, and an L-shaped microstrip branch 12. The resistor pad 5 includes a metal ring and a microstrip line connected in sequence. The inner diameter of the metal ring is consistent with the first metalized through-hole 4, and the microstrip line extends from the metal ring toward the radiation gap 3. The rectangular microstrip branch 6 serves as both a resistor pad and a PIN diode pad, spanning part of the radiation gap 3. The stepped microstrip branch 8 serves as a PIN diode pad, spanning part of the radiation gap 3, and is connected in series with the metal ring 10 and the L-shaped microstrip branch 12 respectively. The metal ring 10 surrounds the second metalized through-hole 9 and has an inner diameter larger than the second metalized through-hole 9. The microstrip line of the resistor pad 5, the rectangular microstrip branch 6, and the stepped microstrip branch 8 are located on the connecting line between the first metalized through-hole 4 and the second metalized through-hole 9.

[0010] The L-shaped microstrip branch 12 includes a long branch and a short branch cascaded in sequence. The long branch is perpendicular to the connection line between the first metallized through hole 4 and the second metallized through hole 9, and the short branch is perpendicular to the long branch. The short branch serves as an inductor pad. The metal wire pad 7 is parallel to the short branch of the L-shaped microstrip branch 12 and retains a certain distance, and also serves as an inductor pad.

[0011] A resistor is connected between the resistor pad 5 and the rectangular microstrip branch 6 , a PIN diode is connected between the rectangular microstrip branch 6 and the stepped microstrip branch 8 , and an inductor is connected between the metal wire pad 7 and the L-shaped microstrip branch 12 .

[0012] Furthermore, in the U-groove waveguide 1 , the threshold value of the curvature coefficient is set to 350.

[0013] Furthermore, the curvature coefficient p is taken as 225. The U-shaped slot waveguide 1 introduces a pre-phase through the curvature to break the symmetry of the directivity pattern of the standing wave array.

[0014] Furthermore, in the lower metal layer of the PCB board 2, the length and spacing of the radiation slots in each group of radiation slots are determined by performing wave simulation on a U-shaped waveguide with the same size as the U-shaped slot waveguide 1 to extract the mode field distribution; the length and position of the radiation slot 3 are such that it is located at the electric field circle of the mode field distribution.

[0015] Furthermore, the on-off state of each PIN diode is controlled by PFGA, thereby controlling the short-circuit and open-circuit states of the radiation slot 3, and further controlling the beam pointing of the antenna; the flexible dielectric substrate is provided with a plurality of metallized vias 13 above the short-circuit wall of the U-shaped slot waveguide 1, and the metallized vias 13 pass through part of the flexible dielectric substrate; the number of the metallized vias 13 is consistent with the number of the PIN diodes and is arranged in a rectangular shape; the pins of the PFGA circuit are connected to the metal wire pads 7 in sequence through the metallized vias 13 and the metal wires 11.

[0016] Furthermore, the antenna is fed using a coaxial feeding port and a WR90 standard waveguide; the coaxial feeding port is arranged in the WR90 standard waveguide, and the WR90 standard waveguide is arranged at the input end of the U-shaped slot waveguide 1 and connected to the U-shaped slot waveguide 1.

[0017] The beneficial effects of the present invention are:

[0018] In the antenna described in this invention, the pad is no longer directly connected to the plated through-hole. Instead, it is isolated by a metal ring, which is spaced a certain distance from the plated through-hole. Electromagnetic waves pass through the metal through-hole and couple to the metal ring, forming a pathway. This allows the DC voltage derived from the DC control line of the PIN diode to be grounded at only one end through the metal through-hole, while the other end is independently controlled by the FPGA. Consequently, each group of PIN diodes can be independently programmed and controlled by the FPGA, allowing each gap to be controlled by a single diode. Compared to existing technologies, this structure requires fewer PIN diodes and a simpler DC circuit design, reducing system component cost and design difficulty.

[0019] Compared with traditional reflective array metasurface antennas and phased array antennas, the antenna described in the present invention has the advantages of high efficiency, low cost, far-field and near-field beam steering capabilities, and small size, and has good application prospects in modern indoor communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of the PCB board in the antenna of the present invention;

[0021] Figure 2 This is a schematic diagram of the exploded structure of the antenna of the present invention;

[0022] Figure 3 This is a side view of the overall structure of the antenna of the present invention; DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to the accompanying drawings and examples.

[0024] This embodiment provides a 1-bit standing wave metasurface programmable antenna, and its overall structure diagram is shown in FIG. Figure 3 As shown, the U-shaped slot waveguide 1 and the PCB board 2 are included. The U-shaped slot waveguide 1 is placed with the empty slot facing upward, and the curvature coefficient is less than a set threshold value, which is set to 350 in this embodiment. The U-shaped slot waveguide 1 introduces a certain curvature, thereby introducing a pre-phase to break the symmetry of the directivity pattern of the standing wave array.

[0025] The structural diagram of PCB board 2 is as follows Figure 1 As shown, the upper surface of the U-shaped slot waveguide 1 includes a flexible dielectric substrate, an upper metal layer located on the upper surface of the flexible dielectric substrate, and a lower metal layer located on the lower surface of the flexible dielectric substrate.

[0026] The lower metal layer is a metal strip, which is rectangular and can completely cover the empty slot of the U-shaped slot waveguide 1; a number of groups of radiation slot pairs are periodically opened on the metal strip along the propagation direction of the U-shaped slot waveguide 1; each group of radiation slot pairs includes two identical radiation slots 3, and the two radiation slots 3 are symmetrical about the long axis of the metal strip; for different groups of radiation slot pairs, the length and spacing of the radiation slots 3 are different.

[0027] The length and spacing of the radiation slots in each group of radiation slot pairs are determined by performing wave simulation on a U-shaped waveguide with the same size as the U-shaped slot waveguide 1 to extract the mode field distribution; the length and position of the radiation slot 3 are such that it is located at the electric field circle of the mode field distribution.

[0028] The flexible dielectric substrate has a first metallized through hole 4 on the inner side of each radiation slot 3 and a second metallized through hole 9 on the outer side. The first metallized through hole 4 and the second metallized through hole 9 are symmetrical with respect to the radiation slot 3 .

[0029] The upper metal layer includes a resistor pad 5, a rectangular microstrip branch 6, a stepped microstrip branch 8, a metal ring 10, a metal wire pad 7, and an L-shaped microstrip branch 12. The resistor pad 5 includes a metal ring and a microstrip line connected in sequence. The inner diameter of the metal ring is consistent with the first plated through hole 4, so that the resistor pad 5 and the first plated through hole 4 are electrically connected. The microstrip line extends from the metal ring toward the radiation slot 3. The rectangular microstrip branch 6 serves as both a resistor pad and a PIN diode pad, spanning a portion of the radiation slot 3. The stepped microstrip branch 8 serves as a PIN diode pad, spanning a portion of the radiation slot 3 and connected in series with the metal ring 10 and the L-shaped microstrip branch 12, respectively. The metal ring 10 surrounds the second plated through hole 9 and has an inner diameter larger than the second plated through hole 9. The microstrip line of the resistor pad 5, the rectangular microstrip branch 6, and the stepped microstrip branch 8 are located on the connecting line between the first plated through hole 4 and the second plated through hole 9.

[0030] The L-shaped microstrip branch 12 includes long branches and short branches cascaded in sequence. The long branches are perpendicular to the connecting lines of the first metallized through-hole 4 and the second metallized through-hole 9, and the short branches are perpendicular to the long branches. The short branches serve as inductor pads; the metal wire pads 7 are parallel to the short branches of the L-shaped microstrip branch 12 and maintain a certain distance, and also serve as inductor pads.

[0031] A resistor is connected between the resistor pad 5 and the rectangular microstrip branch 6 , a PIN diode is connected between the rectangular microstrip branch 6 and the stepped microstrip branch 8 , and an inductor is connected between the metal wire pad 7 and the L-shaped microstrip branch 12 .

[0032] The PFGA controls the on / off state of each PIN diode, thereby controlling the short-circuit and open-circuit states of the radiating slot 3 and, in turn, the antenna's beam direction. The flexible dielectric substrate has several metallized vias 13 above the short-circuit wall of the U-slot waveguide 1. These vias 13 pass through a portion of the flexible dielectric substrate. The number of vias 13 matches the number of PIN diodes, arranged in a rectangular pattern. The pins of the PFGA circuit are connected to the wire pads 7 via metallized vias 13 and metal wires 11, respectively.

[0033] The on / off state of each slot is calculated based on the target field diagram. The DC signal output by the FPGA is then introduced into the PIN diode corresponding to the calculated result via metal vias 13, metal wires 11, inductors, L-shaped microstrip branches 12, and stepped microstrip branches 8, causing the corresponding PIN diode to be in the on state. The current on the metal layer on the lower surface of the PCB board 2 flows through the first metallized through-hole 4 connected to the PIN diode, through the PIN diode, to the metal ring 10. The current is coupled through the metal ring 10 to the second metallized through-hole 9 and then flows into the metal layer on the lower surface of the PCB board 2, causing the corresponding radiating slot 3 to be in the short-circuit state. Conversely, the radiating slot 3 with the PIN diode in the off state is in the open-circuit state. The different open-circuit and short-circuit states of each radiating slot 3 in the standing wave slot array can change the direction of the antenna's main lobe. Through coded calculation and FPGA control, the antenna's main lobe direction can be moved to the target direction.

[0034] In order to ensure that the curvature is sufficient so that the standing wave guide 1-bit reflective array metasurface antenna of the present invention has the ability of beam scanning, the curvature coefficient p is taken as 225 in this embodiment, and the path phase obtained by each radiation slot 3 can effectively suppress the formation of grating lobes. The radiation slots on the metal layer on the lower surface of the PCB board 2 are all of the same size, and each radiation slot introduces a different pre-phase to break the symmetry of the directional pattern of the standing wave array. In this embodiment, the distance between each slot and the distance between the end slot 3 and the short-circuit wall are determined by the actual electric field distribution inside the waveguide. Each slot is set to a different length, and different offsets are set between adjacent slots, so that each group of slots is opened at the electric field circle inside the waveguide.

[0035] The portion of the rectangular microstrip branch 6 that spans the radiation slot 3 serves as an extension section, and the length of the extension section enables the resonance point to operate within the target frequency band.

[0036] like Figure 3As shown, the 1-bit standing wave metasurface programmable antenna described in this embodiment is fed by a coaxial feeding port and a WR90 standard waveguide; the WR90 standard waveguide is arranged at the input end of the U-shaped slot waveguide and is connected to the U-shaped slot waveguide; a mounting hole is provided on the WR90 standard waveguide, which is aligned with the feeding probe through-hole and passes through the upper layer of the WR90 standard waveguide; the coaxial feeding port is arranged in the mounting hole of the WR90 standard waveguide, and the feeding probe is inserted into the feeding probe through-hole on the WR90 standard waveguide via the coaxial feeding port for feeding.

[0037] In this embodiment, to enhance PCB flexibility, a TLY-5 dielectric sheet with a thickness of 0.254mm is used. The U-slot waveguide is constructed of aluminum; the diode is the MACOM MADP-000907 in a 0201 package; the RF inductor is the Murata LQP02HQ2N7BZ2; and a 0.1kΩ chip resistor is used for circuit stability and protection. The final slot design length is 14mm, the slot offset is 5mm, and the distance from the end of the slot to the short-circuit wall is 28mm. The spacing between the individual elements on the PCB is 17mm. After assembly into the curvature of the U-slot waveguide, the center-to-center spacing between the slots is reduced to approximately 15.5mm, enabling operation at 10.5GHz.

[0038] like Figure 2 As shown, the waveguide in the standing wave metasurface programmable antenna described in this embodiment can also be replaced by a convex waveguide instead of a U-groove waveguide, and the PCB board also adopts a convex shape with the same curvature. This configuration can enable the antenna to have a larger scanning angle and beamwidth, while the other components and connections remain unchanged.

[0039] In summary, the standing wave metasurface programmable antenna described in the present invention has the advantages of high efficiency, reduced cost, far-field and near-field beam control capabilities, small size, and reduced circuit complexity, and has broken through the technical difficulty of the normal symmetry of the directional pattern in planar 1-bit standing wave beam scanning. A new waveguide slot-PIN diode metasurface unit is designed, which only uses one PIN diode to achieve 1-bit phase and amplitude control of the slot metasurface unit, reducing the cost and complexity of the tributary control circuit design. A method of further using a curved waveguide to provide a spatial path phase to each slot breaks through the technical difficulty of the normal symmetry of the directional pattern in planar 1-bit standing wave beam scanning. This embodiment provides a standing wave waveguide metasurface antenna based on two concave and convex shapes. At 10.5GHz, the concave waveguide achieves beam scanning from -40° to 30° with a maximum gain of 16dBi; the convex waveguide achieves beam scanning of ±50° with a maximum gain of 15dBi.

Claims

1. A 1-bit standing wave metasurface programmable antenna, characterized in that: It comprises a U-shaped slot waveguide (1) and a PCB board (2); the U-shaped slot waveguide (1) is placed with the empty slot facing upward, and the curvature coefficient is less than a set threshold; The PCB board (2) is located on the upper surface of the U-shaped slot waveguide (1), and comprises a flexible dielectric substrate, an upper metal layer located on the upper surface of the flexible dielectric substrate, and a lower metal layer located on the lower surface of the flexible dielectric substrate; The lower metal layer is a metal strip, which is rectangular and can completely cover the empty slot of the U-shaped slot waveguide (1); a plurality of groups of radiation slot pairs are periodically opened on the metal strip along the propagation direction of the U-shaped slot waveguide (1); each group of radiation slot pairs includes two identical radiation slots (3), and the two radiation slots (3) are symmetrical about the long axis of the metal strip; for different groups of radiation slot pairs, the length and spacing of the radiation slots (3) are different; The flexible dielectric substrate has a first metallized through hole (4) on the inner side of each radiation slot (3) and a second metallized through hole (9) on the outer side, and the first metallized through hole (4) and the second metallized through hole (9) are symmetrical about the radiation slot (3); The upper metal layer includes a resistance pad (5), a rectangular microstrip branch (6), a stepped microstrip branch (8), a metal ring (10), a metal wire pad (7) and an L-shaped microstrip branch (12); the resistance pad (5) includes a metal ring and a microstrip line connected in sequence, the inner diameter of the metal ring is consistent with the first metallized through hole (4), and the microstrip line extends from the metal ring toward the radiation gap (3); the rectangular microstrip branch (6) serves as a resistance pad and a PIN diode pad at the same time, and crosses the portion The radiation gap (3) is divided; the stepped microstrip branch (8) serves as a PIN diode pad, spans part of the radiation gap (3), and is connected in series with the metal ring (10) and the L-shaped microstrip branch (12); the metal ring (10) surrounds the second metallized through hole (9), and the inner diameter is larger than the second metallized through hole (9); the microstrip line of the resistor pad (5), the rectangular microstrip branch (6), and the stepped microstrip branch (8) are located on the connection line between the first metallized through hole (4) and the second metallized through hole (9); The L-shaped microstrip branch (12) includes a long branch and a short branch that are sequentially cascaded, the long branch is perpendicular to the connection line of the first metallized through hole (4) and the second metallized through hole (9), the short branch is perpendicular to the long branch, and the short branch serves as an inductor pad; the metal wire pad (7) is parallel to the short branch of the L-shaped microstrip branch (12) and retains a certain distance, and also serves as an inductor pad; A resistor is connected between the resistor pad (5) and the rectangular microstrip branch (6), a PIN diode is connected between the rectangular microstrip branch (6) and the stepped microstrip branch (8), and an inductor is connected between the metal wire pad (7) and the L-shaped microstrip branch (12).

2. The 1-bit standing wave metasurface programmable antenna according to claim 1, characterized in that In the U-groove waveguide (1), the threshold value of the curvature coefficient is set to 350.

3. The 1-bit standing wave metasurface programmable antenna according to claim 1, characterized in that Taking the curvature coefficient p=225, the U-shaped slot waveguide (1) introduces a pre-phase through the curvature to break the symmetry of the directivity pattern of the standing wave array.

4. The 1-bit standing wave metasurface programmable antenna according to claim 1, characterized in that In the lower metal layer of the PCB board (2), the length and spacing of the radiation slots in each group of radiation slot pairs are determined by performing wave simulation on a U-shaped waveguide with the same size as the U-shaped slot waveguide (1) to extract the mode field distribution; the length and position of the radiation slot (3) are such that it is located at the electric field circle of the mode field distribution.

5. The 1-bit standing wave metasurface programmable antenna according to claim 1, characterized in that The on-off state of each PIN diode is controlled by PFGA, thereby controlling the short-circuit and open-circuit states of the radiation slot (3), and further controlling the beam direction of the antenna; a plurality of metallized vias (13) are opened on the flexible dielectric substrate at a position above the short-circuit wall of the U-shaped slot waveguide (1), and the metallized vias (13) pass through a portion of the flexible dielectric substrate; the number of the metallized vias (13) is consistent with the number of the PIN diodes and is arranged in a rectangular shape; the pins of the PFGA circuit are connected to the metal wire pads (7) in sequence through the metallized vias (13) and the metal wires (14).

6. The 1-bit standing wave metasurface programmable antenna according to claim 1, characterized in that The antenna is fed by using a coaxial feeding port and a WR90 standard waveguide; the coaxial feeding port is arranged in the WR90 standard waveguide, and the WR90 standard waveguide is arranged at the input end of the U-shaped slot waveguide (1) and is connected to the U-shaped slot waveguide (1).

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