A broadband polarization-insensitive 1-bit electronically-controlled programmable metasurface antenna

Abstract

The application discloses a broadband polarization-insensitive 1-bit electrically-controlled programmable metasurface antenna, which comprises an electrically-controlled programmable metasurface and a feed horn, and the electrically-controlled programmable metasurface comprises M*N periodically arranged metasurface units, the unit comprises, from top to bottom, a metal layer one, a high-frequency dielectric substrate one, a metal layer two, a prepreg layer, a metal layer three, a high-frequency dielectric substrate two and a metal layer four, which are coaxially stacked in sequence; a metalized through hole is arranged at the center of the metasurface unit, the metalized through hole vertically penetrates through the high-frequency dielectric substrates and the prepreg layer and is connected with all the metal layers except the metal layer two; metalized blind holes are arranged around the metasurface unit, the metalized blind holes vertically penetrate through the high-frequency dielectric substrate one and are connected with the metal layer one and the metal layer two; four parallel PIN diodes are arranged on the metal layer one; the metasurface antenna has the characteristics of wide frequency band, full polarization compatibility, high polarization isolation and simple structure, and is suitable for satellite communication and 5 / 6G mobile communication.

Description

Technical Field

[0001] This invention belongs to the field of metasurface antenna technology, and particularly relates to a broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna. Background Technology

[0002] As wireless communication systems evolve to the 5th / 6th generation, the integration of air, space, and sea, and the Internet of Things are two major trends in current communication technology development. Metasurface antennas, with their high gain, reconfigurable beamforming, fast beam scanning, and multi-beam generation characteristics, can meet the demands of modern communication systems for high speed, high throughput, and low latency. Electrically controlled programmable metasurface antennas integrate semiconductor tuning devices on each unit of the metasurface, dynamically adjusting the phase distribution of the entire array by controlling the phase response of independent or grouped control units. This approach allows for flexible pointing and rapid switching of high-gain beams without altering the physical structure, adapting to diverse communication scenarios and service requirements. Furthermore, space feeding is a commonly used feeding method. Compared to complex and high-loss feeding networks, space feeding significantly simplifies the structure and reduces system losses and manufacturing costs.

[0003] However, the inherent narrowband characteristics of metasurface elements limit the overall operating bandwidth of antennas built upon them. In existing technologies, there are three main approaches to achieving multi-polarized broadband metasurface antennas: The first approach is based on the principle of polarization rotation. It utilizes anisotropic element structures to rotate the polarization of electromagnetic waves incident at a specific angle by 90°, thus making the reflected wave orthogonal to the incident wave and achieving a stable 180° phase difference. For example, Chinese patent CN119275546B discloses a broadband 1-bit reconfigurable circularly polarized reflective array antenna based on a multi-resonant structure. By placing two pairs of PIN diodes in opposite directions, the elements achieve anisotropy and polarization rotation. Combined with composite patterned metal patches, its operating frequency band is 19.0 GHz to 28.8 GHz, with a relative bandwidth of 41.34%. However, this approach requires a specific incident angle, is incompatible with vertical / horizontal polarization, and requires both positive and negative bias voltages for the elements.

[0004] The second type of approach: Based on the tuning principle, a multi-layer stacked structure is designed to excite adjacent resonant points, utilizing the superposition effect of the resonant points to extend the bandwidth. For example, the literature (S.-G. Zhou et al., “A Wideband 1-Bit Reconfigurable Reflectarray Antenna at Ku-Band,” IEEE Antennas and Wireless Propagation Letters, vol. 21, no. 3, pp. 566–570, Mar. 2022, doi: 10.1109 / LAWP.2021.3138438.) uses rectangular patches and slotted square patches printed on the upper and middle dielectric substrates to form a multi-layer stacked structure, with an operating frequency band of 12.9 GHz to 16.5 GHz and a relative bandwidth of 22.5%; however, the multi-layer stacked structure increases the processing complexity, accuracy requirements, and manufacturing cost, and the antenna is only single y-polarized.

[0005] The third approach involves integrating a discrete broadband antenna with a phase shifter. For example, Chinese patent CN119315281B discloses an ultra-wideband amplitude-phase independent reconfigurable metasurface controlled by a single PIN diode. This metasurface uses a vertically tightly coupled antenna array as a resonator in the 0.5-1.5 GHz band, combined with a 1-bit broadband phase shifter based on microstrip circuitry. Only a single PIN diode is needed to achieve ultra-wideband amplitude-phase independent adjustment. However, this vertical structure increases the profile height, complexity, and assembly process, and it only supports single polarization. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide a broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna. By employing a centrally rotationally symmetrical metal radiating patch structure, coupled with four synchronously on / off PIN diodes as RF switches, broadband phase modulation of incident waves with arbitrary polarization is achieved. It possesses a large-angle beam scanning capability of ±60° under various polarizations and high polarization isolation. Based on the tuning principle, the single-layer multi-resonant integrated metal radiating patch structure significantly expands the operating bandwidth, covering 50.0% of the frequency resources in the X-band (10.0-12.0 GHz) and 83.3% of the frequency resources in the Ku-band (12.0-17.0 GHz), while reducing profile height and assembly complexity, and achieving full polarization compatibility. By creating square annular grooves with notches on the square metal patch, not only is the bandwidth increased, but the DC bias network structure of the electrically controlled programmable metasurface is also simplified, reducing manufacturing costs. Therefore, the metasurface antenna proposed in this invention has the characteristics of wide bandwidth, full polarization compatibility, high polarization isolation, simple structure and low manufacturing cost, and is suitable for satellite communication and 5 / 6G mobile communication systems, meeting the requirements of high-speed transmission and large bandwidth.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0008] A broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna includes an electrically controlled programmable metasurface and a fed horn. The electrically controlled programmable metasurface includes M×N periodically arranged metasurface units. Each metasurface unit includes, from top to bottom, a coaxially stacked metal layer 1, a high-frequency dielectric substrate 1, a metal layer 2, a prepreg layer, a metal layer 3, another high-frequency dielectric substrate 2, and a metal layer 4. A metallized via is provided at the center of each metasurface unit, which vertically penetrates all high-frequency dielectric substrates and prepreg layers and connects all metal layers except for metal layer 2. Metallized blind vias are provided around each metasurface unit, which vertically penetrate high-frequency dielectric substrate 1 and connect metal layer 1 and metal layer 2. Four parallel PIN diodes are provided on metal layer 1 for controlling the reflection phase response of the metasurface unit.

[0009] The first metal layer is centrally rotate symmetrically distributed and includes four metal radiating patches located on the first high-frequency dielectric substrate. A cross-shaped metal connecting bridge is provided in the middle of the four metal radiating patches. The metal connecting bridge and the four metal radiating patches are connected through four PIN diodes to form a parallel equivalent circuit structure.

[0010] The metal radiating patch includes a square metal patch and two L-shaped metal branches connected to the edge of the square metal patch. The L-shaped metal branches include long branches and short branches connected vertically. The long branches of the two L-shaped metal branches are connected to each other, and their short branches all face the metal connecting bridge. There is a certain gap between the short branches and the square metal patch. The square metal patch has a square annular groove with a notch facing the metal connecting bridge. The inner side of the square annular groove is connected to four rectangular grooves, and each rectangular groove is located at the center of the corresponding side of the square annular groove.

[0011] The second metal layer is a metal ground layer; the third metal layer is a metal disk radio frequency isolation structure; the fourth metal layer is a DC bias trace located on the back side of the second high-frequency dielectric substrate, and the M×N DC bias traces constitute the DC bias network structure of the electrically controlled programmable metasurface.

[0012] The metal substrate is etched with isolation holes surrounding the metallized vias, the diameter of which is larger than the diameter of the metallized vias.

[0013] The metal radiating patch is connected to the metal ground plane through a metallized blind via. The metal radiating patch is connected to the metal connecting bridge through a PIN diode. The metal connecting bridge is connected to the DC bias trace through a metallized via, providing bias voltage to the four parallel PIN diodes synchronously.

[0014] The period of the metasurface unit does not exceed 9.45 mm.

[0015] The feeding horn is one of the following: WR75 horn antenna, LB-60180 double-ridged horn antenna, or Vivaldi antenna, used as a feed source for space feeding.

[0016] Both the first high-frequency dielectric substrate and the second high-frequency dielectric substrate are either F4B type high-frequency dielectric substrates or Rogers type high-frequency dielectric substrates.

[0017] Calculate the first step according to the phase compensation formula. The compensation phase required by the theory of each metasurface unit is quantized according to the 1-bit phase quantization criterion, and the conduction or cutoff of the PIN diode of the corresponding metasurface unit is controlled based on the discrete phase distribution after quantization.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. This invention employs four metal radiating patches with central rotational symmetry, along with four synchronously turned-on or turned-off PIN diodes as radio frequency switches, enabling the metasurface unit to generate consistent amplitude and phase responses to orthogonal bilinearly polarized incident waves. This allows the metasurface unit to have 1-bit phase modulation capability for incident waves of any polarization, including linear and circular polarization, providing a wideband 180° reflection phase difference, while also possessing a large-angle beam scanning capability of ±60° under each polarization wave and high polarization isolation.

[0020] 2. The metal radiating patch structure provided by this invention is a single-layer multi-resonant structure. It is a square annular groove with a notch structure opened on a traditional square metal patch and loaded with L-shaped metal branches, achieving a working bandwidth of more than 50% and maintaining a reflection loss of ≤1.53dB across the entire frequency band (10.0-17.0GHz), effectively broadening the working bandwidth of the metasurface unit. Compared with the notchless annular groove design, the metal at the notch is used to directly connect the negative terminal of the PIN diode to the overall metal radiating patch, and then connects to the metal ground layer as the negative terminal of the DC circuit through a metallized blind via. This avoids the need for an additional inductor to connect the diode and the metal ground layer in the traditional solution, simplifying the DC bias network structure of the electronically controlled programmable metasurface.

[0021] 3. Compared with the existing polarization rotation scheme which requires both positive and negative bias voltages, each metasurface unit of the present invention only requires a single independent DC bias trace and only needs to apply a 0V or 1.35V bias voltage to synchronously control the conduction or cutoff of four PIN diodes, reducing the amount of wiring and significantly reducing the processing complexity and manufacturing cost.

[0022] 4. The metasurface unit of the present invention integrates the DC bias network with the metasurface unit by setting the DC bias network structure on the back side of the high-frequency dielectric substrate, thereby improving the integration of the antenna and reducing the overall cross-section; and the electronically controllable programmable metasurface is a press-fit structure of metal layer and dielectric substrate, and the entire structure can be manufactured in one piece using standard printed circuit board (PCB) process, which simplifies the manufacturing process.

[0023] In summary, the metasurface antenna proposed in this invention features wide bandwidth, full polarization compatibility, high polarization isolation, simple structure, and low manufacturing cost, making it suitable for satellite communication and 5 / 6G mobile communication systems, and meeting the requirements for high-speed transmission and large bandwidth. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the metasurface antenna of the present invention.

[0025] Figure 2 This is a schematic diagram of the hierarchical structure of the electrically controlled programmable metasurface of the present invention.

[0026] Figure 3 This is a schematic diagram of the 3D layered structure of the metasurface unit of the present invention.

[0027] Figure 4 A top view of the metasurface unit of the present invention.

[0028] Figure 5a This is a top view of the electrically controlled programmable metasurface of the present invention.

[0029] Figure 5b This is a bottom view of the electrically controlled programmable metasurface of the present invention.

[0030] Figure 6a The surface current distribution of the metal radiation patch and the second metal layer in state "1" of the metasurface unit of the present invention when u-polarized electromagnetic wave is incident.

[0031] Figure 6b The surface current distribution of the metal radiation patch and the second metal layer in state "0" of the metasurface unit of the present invention is shown.

[0032] Figure 7a The surface current distribution of the metal radiation patch and the second metal layer in state "1" of the metasurface unit of the present invention when x-polarized electromagnetic waves are incident.

[0033] Figure 7b The surface current distribution of the metal radiation patch and the second metal layer in state "0" of the metasurface unit of the present invention when x-polarized electromagnetic waves are incident.

[0034] Figure 8a The reflection amplitude of the metasurface unit of the present invention when a u-polarized electromagnetic wave is incident.

[0035] Figure 8b This represents the reflection phase of the metasurface unit of the present invention when a u-polarized electromagnetic wave is incident.

[0036] Figure 8c The reflection amplitude of the metasurface unit of the present invention when an x-polarized electromagnetic wave is incident.

[0037] Figure 8d This represents the reflection phase of the metasurface unit of the present invention when an x-polarized electromagnetic wave is incident.

[0038] Figure 9 This is a schematic diagram illustrating the beam modulation and phase compensation principle of the metasurface antenna of the present invention.

[0039] Figure 10 This is a state distribution diagram of the metasurface unit corresponding to the metasurface antenna of the present invention when the beam direction is (15°, 90°).

[0040] Figure 11aThis is the beam scanning pattern of the metasurface antenna of the present invention at 11.0 GHz.

[0041] Figure 11b The image shows the beam pattern of the metasurface antenna of the present invention at 13.0 GHz.

[0042] Figure 11c This is the beam scanning pattern of the metasurface antenna of the present invention at 16.0 GHz.

[0043] Figure 11d This is the beam scanning pattern of the metasurface antenna at 13.0 GHz when a left-handed circularly polarized wave is incident.

[0044] Figure 11e This refers to the axial ratio of the metasurface antenna of the present invention during the left-hand circularly polarized beam scanning process.

[0045] Figure 11f The axial ratio of the left-hand circularly polarized main beam of the metasurface antenna of the present invention is given in the operating frequency band.

[0046] Figure 12a The gain of the metasurface antenna of the present invention is given in the operating frequency band of 10.0-17.0 GHz.

[0047] Figure 12b The aperture efficiency of the metasurface antenna of the present invention is within the operating frequency band of 10.0-17.0 GHz.

[0048] In the diagram: 1. Powered horn, 11. Horn mounting hole, 2. Electronically controlled programmable metasurface, 21. Metasurface mounting hole, 3. Nylon bracket, 4. Metasurface unit, 41. Metal layer 1, 411. Metal radiating patch, 4111. Square metal patch, 4111. L-shaped metal branch, 4112. Square annular groove, 4113. Notch, 4114. Rectangular groove, 4115. Metal radiating patch 1, 411a. Metal radiating patch 2, 411b. Metal radiating patch 3, 411c. Metal radiating patch 4, 411d. Metal connecting bridge, 412. Circular patch, 4121. Rectangular patch, 4122. PIN diode, 413. High-frequency dielectric substrate 1, 42. Metal layer 2, 43. Prepreg layer, 44. Metal layer 3, 45. High-frequency dielectric substrate 2, 46. Metal layer 4, 47. DC bias trace, 471. Slot interface, 472. Metallized through hole, 48. Metallized blind hole, 49. Detailed Implementation

[0049] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0050] like Figure 1As shown, a broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna includes an electrically controlled programmable metasurface 2 and a feed horn 1 that provides incident electromagnetic waves to the electrically controlled programmable metasurface 2. The feed horn 1 is located on one side of the electrically controlled programmable metasurface 2 and faces the center of the positive end face of the electrically controlled programmable metasurface 2. Both the feed horn 1 and the electrically controlled programmable metasurface 2 are fixed by a nylon bracket 3. The feed horn 1 is one of a WR75 horn antenna, an LB-60180 double-ridged horn antenna, or a Vivaldi antenna, and is used as a feed source for space feeding.

[0051] like Figure 2 As shown, the electrically controllable programmable metasurface 2 is composed of a multilayer composite dielectric structure, including M×N periodically arranged metasurface units 4; according to the array antenna's no-grating-lobe scanning condition, i.e., periodic... , For the wavelength corresponding to the frequency, the period P of the metasurface unit 4 does not exceed 9.45 mm to avoid grating lobes when the beam scans to 60°. The metasurface unit 4 includes, from top to bottom, a coaxially stacked metal layer 41, a high-frequency dielectric substrate 42, a metal layer 43, a prepreg layer 44, a metal layer 45, a high-frequency dielectric substrate 46, and a metal layer 47. A metallized via 48 is provided at the center of the metasurface unit 4. The metallized via 48 vertically penetrates all high-frequency dielectric substrates and prepreg layers 44 and connects all metal layers except for metal layer 43. Metallized blind vias 49 are provided around the perimeter of the metasurface unit 4. The metallized blind vias 49 vertically penetrate the high-frequency dielectric substrate 42 and connect metal layer 41 and metal layer 43, and terminate at metal layer 43.

[0052] Both the high-frequency dielectric substrate 42 and the high-frequency dielectric substrate 46 are F4B type high-frequency dielectric substrates or Rogers type high-frequency dielectric substrates, with a relative permittivity of... The relative permittivity is approximately 2.65. Different types of dielectric substrates generally have different relative permittivity. The equivalent electrical size can be maintained by scaling the size of the metasurface unit 21 proportionally, thereby ensuring the working performance of the metasurface unit 4. Specifically, when selecting a relative permittivity... For substrates with higher dielectric constants, the size of the metasurface unit 21 needs to be reduced proportionally; conversely, it needs to be enlarged proportionally. This size compensation method can effectively offset the influence of dielectric constant differences on resonance characteristics and maintain the electromagnetic response characteristics of the electrically controlled programmable metasurface 2 in the target frequency band. The prepreg layer 44 is a Rogers 4450F type prepreg.

[0053] like Figure 3 and Figure 4As shown, the overall structure of the metal layer 41 is centrally rotate symmetrically distributed, including four metal radiating patches 411 located on the high-frequency dielectric substrate 42, namely metal radiating patch 411a, metal radiating patch 411b, metal radiating patch 411c, and metal radiating patch 411d; a cross-shaped metal connecting bridge 412 is provided in the middle of the four metal radiating patches 411, the metal connecting bridge 412 includes a central circular patch 4121 and four rectangular patches 4122 that are cross-connected to the circular patch 4121; a vertically penetrating metallized through-hole 48 is provided at the center point of the circular patch 4121. Because the metal bridge 412 needs to ensure efficient flow of RF current between the four metal radiating patches 411, the diameter D1 of the circular patch 4121 needs to be larger than the diameter D2 of the metallized via 48, and half of the difference between their diameters should be similar to the width W4 of the rectangular patch 4122 to optimize the RF current path, achieve smooth impedance transition, and uniform current distribution. The metal bridge 412 and the four metal radiating patches 411 are connected by four PIN diodes 413, forming a parallel equivalent circuit structure; the positive terminal of the PIN diode 413 is soldered to the rectangular patch 4122 of the metal bridge 412, and its negative terminal is soldered to the corresponding metal radiating patch 411. Each metal radiating patch 411 has a vertically penetrating metallized blind via 49 at its center point. Each of the aforementioned metal radiating patches 411 includes a square metal patch 4111 and two L-shaped metal branches 4112 connected to the edge of the square metal patch 4111; each L-shaped metal branch 4112 includes a long branch and a short branch connected vertically, the long branches of the two L-shaped metal branches 4112 are interconnected, and their short branches both face the metal connecting bridge 412, such as... Figure 4 The dotted arrow points to the area; and there is a certain gap W5 between the short branch and the square metal patch 4111; the square metal patch 4111 has a square annular groove 4113, the square annular groove 4113 is cut with a notch 4114 facing the metal connecting bridge 412, and four rectangular grooves 4115 are connected to the inner side of the square annular groove 4113, and each rectangular groove 4115 is located at the center of the corresponding side of the square annular groove 4113.

[0054] like Figure 3As shown, the second metal layer 43 is a continuous metal ground layer used to reflect electromagnetic waves; the third metal layer 45 is a metal disk radio frequency isolation structure used to isolate DC signals from radio frequency signals; the fourth metal layer 47 is a DC bias trace 471 used to provide an independently controllable 0V (off state) or 1.35V (on state) bias voltage to control the conduction or cutoff of the PIN diode 413; the fourth metal layer 47 is a DC bias trace 471 located on the back of the second high-frequency dielectric substrate 46. Each metasurface unit 4 only needs one DC bias trace 471. Therefore, the DC bias network of the entire electrically controlled programmable metasurface 2 consists of M×N DC bias traces 471. Each DC bias trace 471 is connected to the output port of the programmable DC control circuit board at the back end through the corresponding slot interface 472. Each top-layer metal radiating patch 411 is connected to the metal ground plane through a metallized blind via 49. The metal radiating patch 411 is connected to a metal connecting bridge 412 through a PIN diode 413. The metal connecting bridge 412 is connected to the bottom-layer DC bias trace 471 through a metallized via 48, synchronously providing a bias voltage of 0 or 1.35V to the four parallel PIN diodes 413. To avoid direct conductive contact between the metallized via 48 and the metal ground plane, which could cause a DC short circuit, an isolation via 431 is etched around the metallized via 48 on the metal ground plane, with a diameter larger than the diameter D2 of the metallized via 48.

[0055] like Figure 5a and Figure 5b As shown, in this embodiment, the programmable metasurface 2 has 12 uniformly distributed non-metallic metasurface fixing holes 21 at its four edges. Nylon screws are used to fix the electronically controlled programmable metasurface 2 to the nylon bracket 3 through the metasurface fixing holes 21. The feed horn 1 uses a WR75 horn antenna, which is fixed to the nylon bracket 3 through the positioning holes on its flange and four horn fixing holes 11, completing the assembly of the entire electronically controlled programmable metasurface antenna. The effective central area of ​​the electronically controlled programmable metasurface 2 has a size of 108mm × 108mm, composed of 144 independent metasurface units 4 arranged periodically in a 12×12 pattern. The thickness of the first high-frequency dielectric substrate 42 is 2.5mm, the second high-frequency dielectric substrate 46 is 0.5mm, the prepreg layer 44 is 0.1mm, each metal layer is 0.035mm thick, and the diameter of the third metal layer 45 is 3mm. Figure 4As shown, the length of the long branch is L1, the length of the short branch is L2, the width of the square annular groove 4113 is W1, the length of the rectangular groove 4115 is W2 and its width is W3, the width of the rectangular patch 4122 is W4, the diameter of the metallized blind via 49 is D3, and the detailed structural parameters of the metal layer 41 are shown in Table 1. The DC bias network of the electrically controlled programmable metasurface 2 consists of 144 independent DC bias lines 471. This DC bias network is connected to the output port of the back-end programmable DC control circuit board through 12 slot interfaces 472 arranged around the edge of the effective area of ​​the center of the electrically controlled programmable metasurface 2, providing an independent and controllable bias voltage for each DC bias line 471.

[0056] Table 1 Structural parameters and dimensions of metal layer 41

[0057]

[0058] The working principle of the electronically controlled programmable metasurface antenna is as follows:

[0059] Taking u-polarized incident electromagnetic waves as an example, such as Figure 6a As shown in the figure, the arrows indicate the main induced current flow direction on the surface of the metal radiating patch 411; when the four PIN diodes 413 are simultaneously forward biased and in the ON state, i.e., the metasurface unit 4 is in state "1", strong surface induced current flows through the metal connecting bridge 412 on the metal radiating patches 411b and 411d, which are parallel to the u-polarization direction. The current flow direction is the same as the surface induced current flow direction of the metal layer 43. The entire metasurface unit 4 exhibits an electrical resonant mode, providing approximately 0° of reflection phase compensation; as Figure 6b As shown, when the four PIN diodes 413 are not biased (0V) and are in the OFF state, i.e., the metasurface unit 4 is in state "0", the induced current flowing between the metal radiating patch 411a and 411c parallel to the u-polarization direction is weakened, and the direction of the induced current is opposite to the direction of the surface induced current flow of the metal layer 43. The entire metasurface unit 4 exhibits a magnetic resonance mode, providing approximately 180° of reflection phase compensation. By controlling the four PIN diodes 413 to be synchronously turned on or off, the metasurface unit 4 switches between the two resonance modes, providing a 180° reflection phase difference and achieving 1-bit phase modulation. At the same time, since the main induced current is distributed on the metal radiating patch 411b and 411d parallel to the u-polarization direction, while the induced current on the metal radiating patch 411a and 411c is very small, the metasurface unit has high polarization isolation.

[0060] like Figure 4As shown, due to the high central rotational symmetry of the overall structure of metasurface unit 4, it exhibits consistent amplitude and phase response characteristics to orthogonally u-polarized and v-polarized or x-polarized and y-polarized incident electromagnetic waves. Figure 7a and Figure 7b The distribution of surface induced current in metasurface unit 4 under different states under x-polarized electromagnetic wave incident is shown. The main induced current flows along the x-axis. In state "1", the direction of induced current flow on the surface of metal radiating patch 411 is the same as the direction of induced current flow in metal layer 43; in state "0", the direction of induced current flow on the surface of metal radiating patch 411 is opposite to the direction of induced current flow in metal layer 43. Therefore, the direction of induced current flow is parallel to the polarization direction. In different states, the current flow direction of metal radiating patch 411 and the current flow direction of metal layer 43 are reversed, and metasurface unit 4 is in different resonant modes, realizing different reflection phase responses to incident electromagnetic waves.

[0061] Figure 8a and Figure 8b These represent the reflection amplitude and reflection phase of metasurface unit 4 when a u-polarized electromagnetic wave is incident. Figure 8c and Figure 8d The values ​​represent the reflection amplitude and phase of metasurface unit 4 under x-polarized incident electromagnetic waves, respectively. Under u-polarized and x-polarized electromagnetic wave incident conditions, the reflection coefficient characteristics of metasurface unit 4 show that they have consistent reflection amplitude and phase responses, differing only in cross-polarization, and both remain at extremely low levels. Figure 8a and Figure 8c It can be seen that in state "0", the reflection amplitude loss of u-polarized and x-polarized incident electromagnetic waves in the 10.0-17.0 GHz band is less than 0.06 dB; specifically, under u-polarized incidence, the cross-polarization of this element is below -70 dB; under x-polarized incidence, the cross-polarization of this element is below -43 dB. In state "1", the reflection amplitude loss of u-polarized incident electromagnetic waves does not exceed 1.53 dB and the cross-polarization of this element is below -50 dB; the reflection amplitude loss of x-polarized incident electromagnetic waves does not exceed 1.52 dB and the cross-polarization of this element is below -48 dB. Figure 8b and Figure 8d It can be seen that in the 10.0-17.0 GHz frequency band, the metasurface unit 4 under u-polarized and x-polarized incident electromagnetic waves has achieved a stable phase difference of 180°±30°, with a phase modulation bandwidth of 51.85%, and has a wideband 1-bit phase modulation capability.

[0062] The structure of the metasurface unit 4 exhibits high central rotational symmetry and Figure 8b , Figure 8dIt is known that metasurface unit 4 exhibits completely consistent phase response characteristics for x-polarization, y-polarization, u-polarization, and v-polarization. The reflection amplitude and phase response under the four polarization incident conditions show highly similar and synchronous reflection characteristics. Furthermore, since a circularly polarized wave can be decomposed into two orthogonally linearly polarized wave components with equal amplitude and a 90° phase difference (e.g., x-polarization and y-polarization, or u-polarization and v-polarization), when such orthogonally linearly polarized waves are incident, metasurface unit 4 simultaneously reflects both orthogonally linearly polarized waves. During reflection, the amplitude and phase changes of the two orthogonally linearly polarized waves are identical. That is, metasurface unit 4 maintains equal amplitude and a 90° phase difference during the reflection of the two components, thus reconstructing the original circularly polarized wave. Therefore, this metasurface unit 4 also exhibits identical electromagnetic response characteristics for left-hand circularly polarized (LHCP) and right-hand circularly polarized (RHCP) incident waves, demonstrating full polarization insensitivity.

[0063] Based on the tuning principle, the metal radiating patch structure of the metasurface unit 4 only includes metal layer 41, and the overall structure is a single-layer multi-resonant structure. Therefore, it has two resonant points, one high-frequency and one low-frequency, with a usable frequency band satisfying a 180° phase difference between the two resonant points. In order to expand the operating bandwidth of the metasurface antenna, metal layer 41 is designed as a composite resonant structure with a square annular groove 4113 with a notch 4114 cut into a square metal patch 4111 and an L-shaped metal stub 4112 loaded. The square annular groove 4113 with the notch 4114 effectively extends the metal layer. The surface current path of the radiating patch 411 increases the equivalent electrical size of the metal radiating patch 411 without increasing its physical size, thus achieving antenna miniaturization. Simultaneously, it reserves design space for the L-shaped metal stub 4112. The low-frequency resonant point mainly depends on the overall size of the metal radiating patch 411, while the position of the high-frequency resonant point can be adjusted by changing the length of the L-shaped metal stub 4112 and its distance from the square metal patch 4111, with minimal impact on the low-frequency resonant point. This achieves a wider usable frequency band between the low-frequency and high-frequency resonant points. Figure 8b and Figure 8d As shown.

[0064] The 144 metasurface units 4 of the electrically controlled programmable metasurface 2 can operate independently. The bias voltage of each metasurface unit 4 can be independently set via a programmable DC control circuit board at the rear, controlling the PIN diode 413 to be in a conducting or turning-off state, so that the metasurface unit 4 operates in a phase state with a reflection phase of 0° or 180°. For example... Figure 9 As shown, to achieve beam scanning in a specified direction, a phase compensation formula is derived based on the array antenna beam control calculation formula, and the first phase compensation formula is calculated. The theoretically required compensation phase for each metasurface unit 4 :

[0065]

[0066] in, Indicates the phase center of the feed horn 1 to the... Spatial distance between the centers of the four metasurface units Represents the free space propagation constant. No. The coordinate positions of each metasurface unit 4 on the two-dimensional plane of the electrically controlled programmable metasurface 2. This indicates the elevation and azimuth angles corresponding to the specified beam direction.

[0067] Phase compensation value obtained from theoretical calculation It is continuous, while metasurface unit 4 provides two different phase states, which need to be quantized according to the 1-bit phase quantization criterion. Quantized into one of two discrete values Generally, there are two discrete values, 0° and 180°, corresponding to state "0" and state "1" of metasurface unit 4, respectively; the quantization standard adopted in this invention is as follows:

[0068]

[0069] Quantization phase shift simplifies the control mechanism of metasurface unit 4. By precisely controlling the discrete phase of all metasurface units 4, the required discrete phase distribution is synthesized on the electrically controlled programmable metasurface 2, realizing the modulation of the electromagnetic wavefront and thus achieving the beam scanning function of the metasurface antenna; such as Figure 10 The figure shows the state distribution of the metasurface unit corresponding to the beam pointing direction (15°, 90°) of the metasurface antenna of the present invention.

[0070] Figure 11a , Figure 11b , Figure 11c These are the linearly polarized beam scanning patterns of the metasurface antenna at different frequency points; among them... Figure 11a The beam scanning of the metasurface antenna at 11.0 GHz is shown. The maximum beam gain corresponding to scanning angles of 0°, 15°, 30°, 45°, and 60° are 15.71 dBi, 15.06 dBi, 14.38 dBi, 14.62 dBi, and 12.77 dBi, respectively. The scanning gain loss is 2.94 dB, and the maximum sidelobe level of the scan is below -8.73 dB. Figure 11b The beam scanning of the metasurface antenna at 13.0 GHz is shown. The maximum beam gain corresponding to scanning angles of 0°, 15°, 30°, 45°, and 60° are 17.60 dBi, 16.40 dBi, 17.43 dBi, 16.63 dBi, and 14.70 dBi, respectively. The scanning gain loss is 2.9 dB, and the maximum sidelobe level of the scan is below -9.13 dB. Figure 11cThe beam scanning performance of the metasurface antenna at 16.0 GHz is shown. The maximum beam gain at scanning angles of 0°, 15°, 30°, 45°, and 60° are 18.72 dBi, 19.01 dBi, 18.83 dBi, 18.62 dBi, and 16.25 dBi, respectively, with a scanning gain loss of 2.76 dB. The maximum sidelobe level during scanning is below -9.13 dB. Within a 3 dB scanning loss range, the metasurface antenna can achieve large-angle beam scanning from 0 to 60° with good beam directivity. The results demonstrate that the metasurface antenna exhibits excellent scanning performance at the three characteristic frequency points of 11.0 GHz (low frequency), 13.0 GHz (mid frequency), and 16.0 GHz (high frequency), verifying its excellent wideband beam control capability across the entire operating frequency band.

[0071] Figure 11d The image shows the beam pattern of the metasurface antenna at 13.0 GHz when a left-hand circularly polarized wave is incident. The maximum beam gain corresponding to scanning angles of 0°, 15°, 30°, 45°, and 60° are 17.59 dBic, 17.74 dBic, 17.68 dBic, 16.40 dBic, and 15.35 dBic, respectively. The scanning gain loss is 2.39 dB, and the maximum sidelobe level of the scan is below -10.39 dB. Figure 11e To account for the change in axial ratio during the scanning process of the left-hand circularly polarized beam, the axial ratio of the metasurface antenna is always kept within 3dB within the scanning range of 0~60° of the circularly polarized beam. Its 3dB axial ratio beamwidth is not less than 15° and can be extended to a maximum scanning angle of 75°. Figure 11f The axial ratio of the left-hand circularly polarized main beam is given in the operating frequency band of 10.0-17.0 GHz. Within the 10.5-17.0 GHz band, the axial ratio of the circularly polarized wave is less than 1.5 dB. Figure 11d , Figure 11e as well as Figure 11f It is known that the metasurface antenna proposed in this invention has broadband large-angle beam scanning capability under left-hand circular polarization beam. Combined with the multi-polarization compatibility characteristics of the metasurface antenna, the metasurface antenna proposed in this invention can also achieve broadband large-angle beam scanning under right-hand circular polarization beam.

[0072] Figure 12a and Figure 12bThe figure shows the gain and aperture efficiency of the main beam of the metasurface antenna in the operating frequency band of 10.0-17.0 GHz. As can be seen from the figure, the 3dB gain bandwidth of the metasurface antenna covers 11.0-17.0 GHz, with a relative bandwidth of 42.86%. The aperture efficiency is better than 13% throughout the entire operating frequency band, with a peak aperture efficiency of 21.17% at 12.0 GHz and a peak gain of 18.72 dB at 16.0 GHz. It exhibits high aperture efficiency in a wide frequency band, indicating that the metasurface antenna has good broadband radiation characteristics.

[0073] In summary, the metasurface antenna proposed in this invention achieves a stable phase difference of 180°±30° for the metasurface elements within the 10.0-17.0 GHz range using a simple structure and highly central rotational symmetry design. The phase modulation relative bandwidth reaches 51.85%, and the reflection loss is less than 1.53 dB. Within the ultra-wide operating band, it maintains a 3 dB gain bandwidth of 42.86% (11.0-17.0 GHz) and an aperture efficiency of over 13% across the entire band. Furthermore, it exhibits polarization insensitivity and a 60° large-angle beam scanning capability, achieving a peak aperture efficiency of 21.17%. Simultaneously, it maintains excellent circular polarization characteristics with an axial ratio within 3 dB throughout the circular polarization beam scanning process. The metasurface antenna proposed in this invention demonstrates significant advantages in wideband operation, multi-polarization compatibility, and large-angle beam modulation, providing an ideal technical solution for next-generation intelligent beamforming systems and possessing significant engineering value in high-frequency applications such as satellite communication and radar detection.

Claims

1. A broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna, comprising an electrically controlled programmable metasurface (2) and a fed horn (1), characterized in that: The electronically controlled programmable metasurface (2) includes M×N periodically arranged metasurface units (4). Each metasurface unit (4) includes, from top to bottom, a metal layer 1 (41), a high-frequency dielectric substrate 1 (42), a metal layer 2 (43), a prepreg layer (44), a metal layer 3 (45), a high-frequency dielectric substrate 2 (46), and a metal layer 4 (47) stacked coaxially. A metallized via (48) is provided at the center of each metasurface unit (4). The metallized via (48) vertically penetrates all high-frequency dielectric substrates and prepreg layers (44) and connects all metal layers except for metal layer 2 (43). Metallized blind vias (49) are provided around each of the metasurface units (4). The metallized blind vias (49) vertically penetrate high-frequency dielectric substrate 1 (42) and connect metal layer 1 (41) and metal layer 2 (43). Four parallel PIN diodes (413) are provided on metal layer 1 (41) for controlling the reflection phase response of the metasurface unit (4). The first metal layer (41) is centrally rotationally symmetrically distributed, including four metal radiating patches (411) located on the first high-frequency dielectric substrate (42). A cross-shaped metal connecting bridge (412) is provided at the center of each of the four metal radiating patches (411). The metal connecting bridge (412) is connected to the four metal radiating patches (411) via four PIN diodes (413), forming a parallel equivalent circuit structure. Each metal radiating patch (411) includes a square metal patch (4111) and two L-shaped metal branches (4112) connected to the edge of the square metal patch (4111). 4112) includes vertically connected long branches and short branches. The long branches of the two L-shaped metal branches (4112) are connected to each other, and their short branches all face the metal connecting bridge (412). There is a certain gap between the short branches and the square metal patch (4111). The square metal patch 4111 is provided with a square annular groove (4113). The square annular groove (4113) is provided with a notch (4114) facing the metal connecting bridge (412). The inner side of the square annular groove (4113) is connected to four rectangular grooves (4115), and each rectangular groove (4115) is located at the center of the corresponding side of the square annular groove (4113).

2. The broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna according to claim 1, characterized in that: The second metal layer (43) is a metal ground layer; the third metal layer (45) is a metal disk radio frequency isolation structure; the fourth metal layer (47) is a DC bias trace (471) located on the back of the second high frequency dielectric substrate (46), and the M×N DC bias traces (471) constitute the DC bias network structure of the electrically controlled programmable metasurface (2).

3. The broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna according to claim 2, characterized in that: The metal substrate is etched with an isolation hole (431) surrounding the metallized via (48), the diameter of which is larger than the diameter of the metallized via (48).

4. A broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna according to claim 2, characterized in that: The metal radiating patch (411) is connected to the metal ground plane through a metallized blind via (49). The metal radiating patch (411) is connected to the metal connecting bridge (412) through a PIN diode (413). The metal connecting bridge (412) is connected to the DC bias trace (471) through a metallized via (48) to synchronously provide bias voltage to the four parallel PIN diodes (413).

5. A broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna according to claim 1, characterized in that: The period of the metasurface unit 4 does not exceed 9.45 mm.

6. A broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna according to claim 1, characterized in that: The feeding horn (1) is one of the WR75 horn antenna, LB-60180 double-ridged horn antenna, or Vivaldi antenna, and is used as a feed source for space feeding.

7. A broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna according to claim 1, characterized in that: Both the first high-frequency dielectric substrate (42) and the second high-frequency dielectric substrate (46) are F4B type high-frequency dielectric substrates or Rogers type high-frequency dielectric substrates.

8. A broadband polarization-insensitive 1-bit electrically controlled programmable metasurface antenna according to claim 1, characterized in that: Calculate the first step according to the phase compensation formula. The compensation phase required by the theory of each metasurface unit (4) is quantized according to the 1-bit phase quantization criterion, and the conduction or cutoff of the PIN diode (413) of the corresponding metasurface unit (4) is controlled based on the discrete phase distribution after quantization.

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