Broadband polarization insensitive 1-bit electrically-controlled programmable metasurface antenna

Abstract

The invention discloses a broadband polarization insensitive 1-bit electrically-controlled programmable metasurface antenna, which comprises an electrically-controlled programmable metasurface and a feed horn, and is characterized in that the electrically-controlled programmable metasurface comprises M * N periodically arranged metasurface units, the unit comprises a first metal layer, a first high-frequency dielectric substrate, a second metal layer, a prepreg layer, a third metal layer, a second high-frequency dielectric substrate and a fourth metal layer which are sequentially and coaxially stacked from top to bottom. A metalized through hole is formed in the center of the metasurface unit; the metalized through hole vertically penetrates through each high-frequency dielectric substrate and the prepreg layer and is connected with all metal layers except the metal layer II; metalized blind holes are formed in the periphery of the metasurface unit, vertically penetrate through the first high-frequency dielectric substrate and are connected with the first metal layer and the second metal layer; four PIN diodes which are connected in parallel are arranged on the metal layer I; the metasurface antenna provided by the invention has the characteristics of wide frequency band, complete polarization compatibility, high polarization isolation and simple structure, and is suitable for satellite communication and 5 / 6G mobile communication.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metasurface antennas, and particularly relates to a wideband polarization-insensitive 1-bit electrically-controlled programmable metasurface antenna. BACKGROUND

[0002] With the evolution of wireless communication systems to the 5th / 6th generation, space-ground-sea integration and Internet of Everything are two major trends in the development of current communication technologies. Metasurface antennas can meet the needs of modern communication systems for high speed, large throughput and low delay, etc. due to their high gain, reconfigurable beamforming, fast beam scanning and multi-beam generation. Electrically-controlled programmable metasurface antennas integrate semiconductor tuning devices on each unit that constitutes the metasurface, and dynamically adjust the phase distribution of the entire array by independently or in groups controlling the phase response of the units. This way can realize flexible pointing and fast switching of high-gain beams without changing the physical structure, to adapt to diversified communication scenarios and business needs. In addition, spatial feeding is a common feeding method, which significantly simplifies the structure, reduces system loss and manufacturing cost compared to complex and high-loss feeding networks.

[0003] However, the inherent narrowband characteristics of metasurface units limit the overall operating bandwidth of the antennas constructed based thereon. There are mainly three kinds of schemes for realizing multi-polarization wideband metasurface antennas in the prior art: the first kind of scheme: based on the principle of polarization rotation, anisotropic unit structure is used to make the polarization of the electromagnetic wave incident at a specific angle rotate by 90°, so that the polarization of the reflected wave is orthogonal to that of the incident wave, and a stable 180° phase difference is realized. For example, the Chinese patent with publication number CN119275546B discloses a wideband 1-bit reconfigurable circularly polarized reflective array antenna based on a multi-resonant structure, two pairs of PIN diodes are placed in opposite directions, so that the unit produces anisotropy to realize polarization rotation, and a composite pattern metal patch is combined to obtain a working frequency band of 19.0GHz to 28.8GHz, with a relative bandwidth of 41.34%; however, this scheme requires a specific angle of incidence and cannot be compatible with vertical / horizontal polarization, and the unit needs to be provided with positive and negative bias voltages.

[0004] The second approach, based on the tuning principle, uses a multilayer stacked structure to excite adjacent resonant points and expand the bandwidth by exploiting the superposition effect of resonant points. For example, the paper (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.) proposes a multilayer stacked structure composed of rectangular patches and slotted square patches printed on upper and middle dielectric substrates, respectively. This structure operates in the 12.9 GHz to 16.5 GHz band with a relative bandwidth of 22.5%. However, the multilayer stacking structure increases processing complexity, precision requirements, and manufacturing costs, and the antenna is only y-polarized.

[0005] The third solution uses a discrete broadband antenna and phase shifter integrated design. For example, Chinese patent publication number CN119315281B discloses an ultra-wideband, amplitude- and phase-independent reconfigurable metasurface based on single-PIN diode control. In the 0.5-1.5 GHz frequency band, a vertical tightly coupled antenna array is used as a resonator, combined with a 1-bit broadband phase shifter based on a microstrip circuit. Using only a single PIN diode, the unit achieves ultra-wideband, amplitude- and phase-independent adjustable characteristics. However, this solution's vertical structure results in an increased profile, increased complexity, and additional assembly steps, and only supports single polarization. Summary of the Invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a broadband polarization-insensitive 1-bit electrically controllable programmable metasurface antenna. By adopting a metal radiating patch structure with a central rotational symmetric distribution and cooperating with four PIN diodes that are synchronously turned on or off as radio frequency switches, broadband phase control of arbitrarily polarized incident waves is achieved, and the antenna has a large-angle beam scanning capability of ±60° and high polarization isolation under each polarization wave. Based on the tuning principle, a single-layer multi-resonant integrated metal radiating patch structure is adopted to significantly expand the operating bandwidth, covering 50.0% of the frequency resources in the X-band (10.0-12.0GHz) and 83.3% of the frequency resources in the Ku-band (12.0-17.0GHz), while reducing the cross-sectional height and assembly complexity, and achieving full polarization compatibility. By opening a square ring groove with a notch structure on the square metal patch, not only can the bandwidth be increased, but the DC bias network structure of the electrically controllable programmable metasurface can also be simplified, reducing manufacturing costs. Therefore, the metasurface antenna proposed in the present invention has the characteristics of wide bandwidth, full polarization compatibility, high polarization isolation, simple structure and low production cost. It is suitable for satellite communication and 5 / 6G mobile communication systems, and meets the requirements of high-speed transmission and large bandwidth.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is: A broadband polarization-insensitive 1-bit electrically programmable metasurface antenna comprises an electrically programmable metasurface and a feed horn; the electrically programmable metasurface comprises M×N periodically arranged metasurface units; the metasurface unit comprises a metal layer 1, a high-frequency dielectric substrate 1, a metal layer 2, a prepreg layer, a metal layer 3, a high-frequency dielectric substrate 2, and a metal layer 4 coaxially stacked from top to bottom; a metallized through-hole is provided at the center of the metasurface unit, the metallized through-hole vertically penetrates all high-frequency dielectric substrates and prepreg layers and connects all metal layers except metal layer 2; metallized blind holes are provided around the periphery of the metasurface unit, the metallized blind holes vertically penetrate the high-frequency dielectric substrate 1 and connect metal layer 1 and metal layer 2; four parallel PIN diodes are provided on the metal layer 1 for regulating the reflection phase response of the metasurface unit.

[0008] The metal layer 1 is distributed in a central rotationally symmetrical manner, including four metal radiation patches located on a high-frequency dielectric substrate 1. A cross-shaped metal connection bridge is provided in the middle position of the four metal radiation patches. The metal connection bridge is connected to the four metal radiation patches through four PIN diodes to form a parallel equivalent circuit structure.

[0009] The metal radiation 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 the short branches are all facing the metal connection bridge, and there is a certain gap between the short branches and the square metal patch; a square ring groove is opened on the square metal patch, and the square ring groove has a notch facing the metal connection bridge; four rectangular grooves are connected to the inner side of the square ring groove, and each rectangular groove is located at the center of the corresponding side of the square ring groove.

[0010] The metal layer 2 is a metal ground layer; the metal layer 3 is a metal disk radio frequency isolation structure; the metal layer 4 is a DC bias line located on the back of the high-frequency dielectric substrate 2, and M×N DC bias lines constitute a DC bias network structure of the electrically controlled programmable metasurface.

[0011] An isolation hole surrounding the metallized through hole is etched on the metal layer, and the diameter of the isolation hole is larger than the diameter of the metallized through hole.

[0012] The metal radiation patch is connected to the metal ground layer through a metalized blind hole, the metal radiation patch is connected to the metal connection bridge through a PIN diode, and the metal connection bridge is connected to the DC bias trace through a metalized through hole to synchronously provide bias voltage to the four parallel PIN diodes.

[0013] The period of the metasurface unit does not exceed 9.45 mm.

[0014] The feeding horn is one of a WR75 horn antenna, a LB-60180 double-ridged horn antenna, and a Vivaldi antenna, and is used as a feed source for space feeding.

[0015] The first high-frequency dielectric substrate and the second high-frequency dielectric substrate are both F4B-type high-frequency dielectric substrates or Rogers-type high-frequency dielectric substrates.

[0016] According to the phase compensation formula, the The compensation phase theoretically required by each metasurface unit is quantized according to the 1-bit phase quantization criterion, and the on / off of the PIN diode of the corresponding metasurface unit is controlled based on the quantized discrete phase distribution.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention adopts four metal radiation patches with central rotational symmetry, and cooperates with four PIN diodes that are synchronously turned on or off as radio frequency switches, so that the metasurface unit produces consistent amplitude and phase responses to orthogonal dual-linear polarization incident waves, thereby enabling the metasurface unit to have 1-bit phase control capability for incident waves of any polarization form, including linear polarization and circular polarization, providing a wide-band 180° reflection phase difference, and at the same time having a large-angle beam scanning capability of ±60° under each polarization wave and high polarization isolation.

[0018] 2. The metal radiation patch structure provided by the present invention is a single-layer multi-resonance structure, in which a square annular groove with a notch structure is opened on a traditional square metal patch and an L-shaped metal branch is loaded, thereby achieving a working bandwidth of more than 50% and maintaining a reflection loss of ≤1.53dB in the full frequency band (10.0-17.0GHz), effectively broadening the working bandwidth of the metasurface unit; compared with the annular groove design without a notch, the metal at the notch is used to directly connect the negative electrode of the PIN diode to the overall metal radiation patch, and then connected to the metal stratum serving as the negative electrode of the DC circuit through a metallized blind hole, avoiding the need for additional inductance to connect the diode and the metal stratum in the traditional solution, and simplifying the DC bias network structure of the electrically controlled programmable metasurface.

[0019] 3. Compared with the polarization rotation scheme in the prior art that requires providing both positive and negative bias voltages, each metasurface unit of the present invention only requires a single independent DC bias line and only needs to apply a 0V or 1.35V bias voltage to synchronously control the conduction or shutdown of four PIN diodes, reducing the amount of wiring and greatly reducing processing complexity and manufacturing costs.

[0020] 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 2, thereby improving the integration of the antenna and reducing the overall cross-section; and the electrically controlled programmable metasurface as a whole is a pressed structure of the metal layer and the dielectric substrate. The entire structure can be integrated and manufactured through the standard printed circuit board (PCB) process, and the manufacturing process is simple.

[0021] In summary, the metasurface antenna proposed in the present invention has the characteristics of wide bandwidth, full polarization compatibility, high polarization isolation, simple structure and low production cost. It is suitable for satellite communication and 5 / 6G mobile communication systems, and meets the requirements of high-speed transmission and large bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of the metasurface antenna of the present invention.

[0023] Figure 2 Schematic diagram of the hierarchical structure of the electrically controlled programmable metasurface of the present invention.

[0024] Figure 3 Schematic diagram of the 3D layered structure of the super surface unit of the present invention.

[0025] Figure 4 A top view of the metasurface unit of the present invention.

[0026] Figure 5a This is a top view of the electrically controlled programmable metasurface of the present invention.

[0027] Figure 5b This is a bottom view of the electrically controlled programmable metasurface of the present invention.

[0028] Figure 6a This is the surface current distribution of the metal radiation patch and metal layer 2 of the metasurface unit of the present invention in state "1" when u-polarized electromagnetic waves are incident.

[0029] Figure 6b This is the surface current distribution of the metal radiation patch and metal layer 2 of the metasurface unit of the present invention in state "0" when u-polarized electromagnetic waves are incident.

[0030] Figure 7a This is the surface current distribution of the metal radiation patch and metal layer 2 of the metasurface unit of the present invention in state "1" when an x-polarized electromagnetic wave is incident.

[0031] Figure 7b This is the surface current distribution of the metal radiation patch and metal layer 2 of the metasurface unit of the present invention in state "0" when an x-polarized electromagnetic wave is incident.

[0032] Figure 8a It is the reflection amplitude of the metasurface unit of the present invention when u-polarized electromagnetic wave is incident.

[0033] Figure 8b It is the reflection phase of the metasurface unit of the present invention when u-polarized electromagnetic wave is incident.

[0034] Figure 8c It is the reflection amplitude of the metasurface unit of the present invention when x-polarized electromagnetic wave is incident.

[0035] Figure 8d It is the reflection phase of the metasurface unit of the present invention when an x-polarized electromagnetic wave is incident.

[0036] Figure 9 This is a schematic diagram of the beam steering phase compensation principle of the metasurface antenna of the present invention.

[0037] Figure 10 This is the metasurface unit state distribution diagram corresponding to the metasurface antenna of the present invention when the beam direction is (15°, 90°).

[0038] Figure 11aThis is the beam scanning pattern of the metasurface antenna of the present invention at 11.0 GHz.

[0039] Figure 11b This is the beam scanning pattern of the metasurface antenna of the present invention at 13.0 GHz.

[0040] Figure 11c This is the beam scanning pattern of the metasurface antenna of the present invention at 16.0 GHz.

[0041] Figure 11d This is the beam scanning pattern of the metasurface antenna at 13.0 GHz when left-handed circularly polarized waves are incident.

[0042] Figure 11e is the axial ratio of the metasurface antenna of the present invention during left-hand circularly polarized beam scanning.

[0043] Figure 11f It is the axial ratio of the left-handed circularly polarized main beam of the metasurface antenna of the present invention within the operating frequency band.

[0044] Figure 12a It is the gain of the metasurface antenna of the present invention in the working frequency band of 10.0-17.0 GHz.

[0045] Figure 12b It is the aperture efficiency of the metasurface antenna of the present invention in the working frequency band of 10.0-17.0 GHz.

[0046] In the figure: feed horn 1, horn fixing hole 11, electrically controllable programmable metasurface 2, metasurface fixing hole 21, nylon bracket 3, metasurface unit 4, metal layer 1 41, metal radiation patch 411, square metal patch 4111, L-shaped metal branch 4112, square ring groove 4113, notch 4114, rectangular groove 4115, metal radiation patch 1 411a, metal radiation patch 2 411b, metal radiation patch 3 411c, metal radiation 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, semi-preg layer 44, metal layer 3 45, high-frequency dielectric substrate 2 46, metal layer 47, DC bias trace 471, slot interface 472, metalized through hole 48, metalized blind hole 49. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0048] like Figure 1As shown, a broadband polarization-insensitive 1-bit electrically controllable programmable metasurface antenna includes an electrically controllable programmable metasurface 2 and a feeding horn 1 for providing incident electromagnetic waves to the electrically controllable programmable metasurface 2. The feeding horn 1 is located on one side of the electrically controllable programmable metasurface 2 and is facing the center of the positive end face of the electrically controllable programmable metasurface 2. The feeding horn 1 and the electrically controllable programmable metasurface 2 are both fixed by a nylon bracket 3. The feeding horn 1 is one of the WR75 horn antenna, LB-60180 double-ridged horn antenna, and Vivaldi antenna, and is used as a feed source for space feeding.

[0049] like Figure 2 As shown, the electrically controlled programmable metasurface 2 is composed of a multi-layer composite dielectric structure, including M×N periodically arranged metasurface units 4; according to the grating lobe-free scanning condition of the array antenna, that is, the period , The period P of the metasurface unit 4 does not exceed 9.45 mm for the wavelength of the corresponding frequency, so as to avoid the occurrence of grating lobes when the beam scans to 60°; the metasurface unit 4 includes a metal layer 1 41, a high-frequency dielectric substrate 1 42, a metal layer 2 43, a semi-cured sheet layer 44, a metal layer 3 45, a high-frequency dielectric substrate 2 46, and a metal layer 4 47 coaxially stacked from top to bottom; a metallized through-hole 48 is provided at the center of the metasurface unit 4, and the metallized through-hole 48 vertically penetrates all high-frequency dielectric substrates and semi-cured sheet layers 44 and connects all metal layers except the metal layer 2 43; metallized blind holes 49 are provided around the metasurface unit 4, and the metallized blind holes 49 vertically penetrate the high-frequency dielectric substrate 1 42 and connect the metal layer 1 41 and the metal layer 2 43, and terminate at the metal layer 2 43.

[0050] The high-frequency dielectric substrate 1 42 and the high-frequency dielectric substrate 2 46 are both F4B type high-frequency dielectric substrates or Rogers type high-frequency dielectric substrates, with a relative dielectric constant of The relative dielectric constant of different types of dielectric substrates is about 2.65. Generally, the relative dielectric constant of different types of dielectric substrates will be different. The size of the metasurface unit 21 can be scaled proportionally to maintain the equivalent electrical size, thereby ensuring the working performance of the metasurface unit 4. Specifically, when the relative dielectric constant is selected For taller dielectric substrates, the size of the metasurface unit 21 needs to be proportionally reduced; otherwise, it needs to be proportionally enlarged. This size compensation method effectively offsets the effect of dielectric constant differences on the resonant characteristics, maintaining the electromagnetic response characteristics of the electrically controllable programmable metasurface 2 in the target frequency band. The prepreg layer 44 is a Rogers 4450F prepreg.

[0051] like Figure 3 and Figure 4As shown, the overall structure of the metal layer 41 is distributed in a central rotational symmetric manner, including four metal radiation patches 411 located on a high-frequency dielectric substrate 42, namely metal radiation patch 1 411a, metal radiation patch 2 411b, metal radiation patch 3 411c, and metal radiation patch 4 411d; a cross-shaped metal connecting bridge 412 is provided in the middle position of the four metal radiation patches 411, and the metal connecting bridge 412 includes a central circular patch 4121 and four rectangular patches 4122 cross-connected to the circular patch 4121; the center point of the circular patch 4121 is provided with a vertically penetrating metalized through-hole 48. Because the metal bridge 412 must ensure efficient flow of RF current between the four metal radiating patches 411, the diameter D1 of the circular patch 4121 must be larger than the diameter D2 of the metalized through-hole 48, and half of the difference between the two diameters should be close to the width W4 of the rectangular patch 4122 to optimize the RF current path, achieve a smooth impedance transition, and uniform current distribution. The metal bridge 412 and the four metal radiating patches 411 are connected via four PIN diodes 413 to form a parallel equivalent circuit structure; the positive electrode of the PIN diode 413 is welded to the rectangular patch 4122 of the metal bridge 412, and its negative electrode is welded to the corresponding metal radiating patch 411. A metalized blind via 49 is provided vertically through the center point of each metal radiating patch 411. Each of the metal radiation patches 411 includes a square metal patch 4111 and two L-shaped metal branches 4112 connected to the edges of the square metal patch 4111; the L-shaped metal branches 4112 include long branches and short branches connected vertically, the long branches of the two L-shaped metal branches 4112 are connected to each other, and the short branches are all facing the metal connection bridge 412. Figure 4 As indicated by the dotted arrow; and there is a certain interval W5 between the short branch and the square metal patch 4111; a square ring groove 4113 is opened on the square metal patch 4111, and the square ring groove 4113 is cut with a notch 4114 facing the metal connecting bridge 412, and four rectangular grooves 4115 are connected to the inside of the square ring groove 4113, and each rectangular groove 4115 is located at the center of the corresponding side of the square ring groove 4113.

[0052] like Figure 3As shown, the metal layer 2 43 is a continuous metal stratum for reflecting electromagnetic waves; the metal layer 3 45 is a metal disk RF isolation structure for isolating DC signals from RF signals; the metal layer 47 is a DC bias trace 471 for providing an independently controllable bias voltage of 0V (off state) or 1.35V (on state) to control the conduction or shutdown of the PIN diode 413; the metal layer 47 is a DC bias trace 471 located on the back of the high-frequency dielectric substrate 2 46. Each metasurface unit 4 only requires one DC bias trace 471. Therefore, the DC bias network of the entire electrically controlled programmable metasurface 2 is composed 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 rear end through the corresponding slot interface 472. Each top-layer metal radiating patch 411 is connected to the metal ground layer via a metalized blind via 49. Metal radiating patch 411 is connected to a metal bridge 412 via a PIN diode 413. Metal bridge 412 is connected to a DC bias trace 471 on the bottom layer via a metalized through-hole 48, synchronously providing a bias voltage of 0 or 1.35V to the four parallel-connected PIN diodes 413. To prevent direct conductive contact between the metalized through-hole 48 and the metal ground layer, which could cause a DC short circuit, an isolation hole 431 is etched in the metal ground layer, surrounding the metalized through-hole 48. Its diameter is larger than the diameter D2 of the metalized through-hole 48.

[0053] like Figure 5a and Figure 5b As shown, in this embodiment, 12 evenly distributed non-metallized metasurface fixing holes 21 are provided on the four edges of the programmable metasurface 2. Nylon screws are used to fix the electrically controlled programmable metasurface 2 to the nylon bracket 3 through the metasurface fixing holes 21. The feed horn 1 adopts a WR75 horn antenna. The feed horn 1 is fixed to the nylon bracket 3 through the positioning holes on its flange and the four horn fixing holes 11, completing the assembly of the entire electrically controlled programmable metasurface antenna. The central effective area size of the electrically controlled programmable metasurface 2 is 108mm × 108mm, and it is composed of 144 independent metasurface units 4 arranged in a 12×12 periodic pattern. Among them, the thickness of the high-frequency dielectric substrate 1 42 is 2.5mm, the thickness of the high-frequency dielectric substrate 2 46 is 0.5mm, the thickness of the semi-cured sheet layer 44 is 0.1mm, the thickness of each metal layer is 0.035mm, and the diameter of the metal layer 3 45 is 3mm. Figure 4As shown in FIG1 , the length of the long branch is L1, the length of the short branch is L2, the width of the square ring 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 hole 49 is D3, and the detailed structural parameter dimensions of the metal layer 41 are shown in Table 1; the DC bias network of the electrically-controlled programmable metasurface 2 is composed of 144 independent DC bias traces 471, which are 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 central effective area of ​​the electrically-controlled programmable metasurface 2, providing each DC bias trace 471 with an independently controllable bias voltage.

[0054] Table 1 Structural parameters and dimensions of metal layer 41 The working principle of the electrically controlled programmable metasurface antenna is: Take u-polarized incident electromagnetic wave as an example, Figure 6a As shown in the figure, the arrows indicate the direction of the main induced current flow on the surface of the metal radiation patch 411; when the four PIN diodes 413 are synchronously applied with a forward bias voltage and are in the on state, that is, the metasurface unit 4 is in state "1", the metal radiation patch 2 411b and the metal radiation patch 4 411d parallel to the u polarization direction have strong surface induced currents flowing through the metal connecting bridge 412, and the current flow direction is the same as the surface induced current flow direction of the metal layer 2 43. The entire metasurface unit 4 exhibits an electric resonance mode, providing a reflection phase compensation of about 0°; as shown in FIG. Figure 6b As shown, when the four PIN diodes 413 are not biased (0V) and are in the off state, that is, the metasurface unit 4 is in state "0," the induced current flowing between the metal radiating patch 1 411a and the metal radiating patch 3 411c, which are 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 flowing in the metal layer 2 43. The entire metasurface unit 4 exhibits a magnetic resonance mode, providing approximately 180° of reflection phase compensation. By controlling the synchronous conduction or shutdown of the four PIN diodes 413, the metasurface unit 4 switches between the two resonance modes, providing a 180° reflection phase difference and achieving 1-bit phase control. At the same time, because the primary induced current is distributed in the metal radiating patch 2 411b and the metal radiating patch 4 411d, which are parallel to the u polarization direction, while the induced current in the metal radiating patch 1 411a and the metal radiating patch 3 411c is very small, the metasurface unit has high polarization isolation.

[0055] like Figure 4As shown, since the overall structure of the metasurface unit 4 presents a high degree of central rotational symmetry, it has consistent amplitude and phase response characteristics to orthogonal u-polarized and v-polarized or x-polarized and y-polarized incident electromagnetic waves. Figure 7a and Figure 7b The distribution of the surface induced current of the metasurface unit 4 in different states under the incident x-polarized electromagnetic wave is shown. The main induced current flows along the x-axis. In state "1", the direction of the induced current on the surface of the metal radiation patch 411 is the same as the direction of the induced current in the second metal layer 43. In state "0", the direction of the induced current on the surface of the metal radiation patch 411 is opposite to the direction of the induced current in the second metal layer 43. Therefore, the direction of the induced current flow is parallel to the polarization direction. In different states, the current flow direction of the metal radiation patch 411 and the current flow direction of the second metal layer 43 are reversed. The metasurface unit 4 is in different resonant modes, achieving different reflection phase responses to the incident electromagnetic wave.

[0056] Figure 8a and Figure 8b are respectively the reflection amplitude and reflection phase of the metasurface unit 4 when the u-polarized electromagnetic wave is incident, Figure 8c and Figure 8d They are respectively the reflection amplitude and reflection phase of the metasurface unit 4 when the incident electromagnetic wave is x-polarized; under the conditions of u-polarized and x-polarized electromagnetic wave incidence, the reflection coefficient characteristics of the metasurface unit 4 show that the two have consistent reflection amplitude and reflection phase responses, and only the cross-polarization has differences and both are maintained 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 10.0-17.0GHz frequency band is less than 0.06dB; among them, under u-polarized incidence, the cross-polarization of the unit is less than -70dB; under x-polarized incidence, the cross-polarization of the unit is less than -43dB. In state "1", the reflection amplitude loss of u-polarized incident electromagnetic waves does not exceed 1.53dB and the cross-polarization of the unit is less than -50dB, and the reflection amplitude loss of x-polarized incident electromagnetic waves does not exceed 1.52dB and the cross-polarization of the unit is less than -48dB. Figure 8b and Figure 8d It can be seen that in the 10.0-17.0 GHz frequency band, the metasurface unit 4 achieved a stable phase difference of 180°±30° under both u-polarized and x-polarized incident electromagnetic waves, with a phase control bandwidth of 51.85%, and has a wide-band 1-bit phase control capability.

[0057] The structure of the metasurface unit 4 with high central rotational symmetry and Figure 8b 、 Figure 8dIt can be seen that the metasurface unit 4 has completely consistent phase response characteristics for x-polarization, y-polarization, u-polarization, or v-polarization. The reflection amplitude and phase responses under the four polarization incident conditions show highly similar and synchronous reflection characteristics, and the circularly polarized wave can be decomposed into two orthogonal linearly polarized wave components with equal amplitudes and a phase difference of 90°, such as x-polarization and y-polarization, or u-polarization and v-polarization. When such an orthogonal linearly polarized wave is incident, the metasurface unit 4 will simultaneously reflect the two orthogonal linearly polarized waves, and the amplitude and phase changes of the two orthogonal linearly polarized waves during the reflection process are the same, that is, the metasurface unit 4 maintains the same amplitude and 90° phase difference in the reflection process of the two components, thereby reconstructing the original circularly polarized wave. Therefore, the metasurface unit 4 also exhibits equivalent electromagnetic response characteristics to left-hand circularly polarized (LHCP) and right-hand circularly polarized (RHCP) incident waves, that is, it has a fully polarization-insensitive characteristic.

[0058] Based on the tuning principle, the metal radiation patch structure of the metasurface unit 4 only includes a metal layer 41. The overall structure is a single-layer multi-resonance structure, so there are two resonance points, high frequency and low frequency, and there is an available frequency band with a 180° phase difference between the two resonance points. In order to expand the working bandwidth of the metasurface antenna, the metal layer 41 is designed to be a composite resonant structure with a square ring groove 4113 with a notch 4114 cut out on the square metal patch 4111 and loaded with an L-shaped metal branch 4112. The square ring groove 4113 with a notch 4114 is designed to effectively extend the metal The surface current path of the radiation patch 411 is formed, thereby increasing the equivalent electrical size of the metal radiation patch 411 without increasing the physical size, realizing the miniaturization of the antenna, and at the same time reserving design space for the L-shaped metal branch 4112; the low-frequency resonance point mainly depends on the overall size of the metal radiation patch 411, and by adjusting the length of the L-shaped metal branch 4112 and the distance between it and the square metal patch 4111, the position of the high-frequency resonance point can be adjusted, and the influence on the low-frequency resonance point is small, thereby achieving a wider available frequency band between the low-frequency and high-frequency resonance points, such as Figure 8b and Figure 8d shown.

[0059] The 144 metasurface units 4 of the electrically controlled programmable metasurface 2 can work independently. The bias voltage of each metasurface unit 4 is independently set by the programmable DC control circuit board at the rear end, and the PIN diode 413 is controlled to be in the on or off state, so that the metasurface unit 4 works in a phase state with a reflection phase of 0° or 180°. Figure 9 As shown in the figure, in order to realize the beam scanning in the specified direction, the phase compensation formula is derived according to the array antenna beam control calculation formula, and the first Theoretical compensation phase required for 4 metasurface units : in, Indicates the phase center of the feed horn 1 to the The spatial distance between the centers of the metasurface units 4, represents the free space propagation constant, No. The coordinate position of each metasurface unit 4 on the two-dimensional plane of the electrically controlled programmable metasurface 2, Indicates the elevation and azimuth angles corresponding to the specified beam direction.

[0060] Theoretically calculated phase compensation value is continuous, and the metasurface unit 4 provides two different phase states, which need to be quantized according to the 1-bit phase quantization criterion. Quantized to one of two discrete values , which is generally two discrete values ​​of 0° and 180°, corresponding to the states "0" and "1" of the metasurface unit 4, respectively; the quantization standard adopted by the present invention is as follows: The quantized phase shift simplifies the control mechanism of the metasurface unit 4. By precisely controlling the discrete phases of all metasurface units 4, the required discrete phase distribution is synthesized on the electrically controllable programmable metasurface 2 to achieve the control of the electromagnetic wavefront, thereby realizing the beam scanning function of the metasurface antenna. Figure 10 As shown in the figure, the metasurface unit state distribution diagram corresponding to the metasurface antenna of the present invention when the beam pointing is (15°, 90°).

[0061] Figure 11a 、 Figure 11b 、 Figure 11c are the linear polarization beam scanning patterns of the metasurface antenna at different frequencies; Figure 11a This is the beam scanning of the metasurface antenna at the 11.0 GHz frequency. When the scanning angles are 0°, 15°, 30°, 45°, and 60°, the corresponding maximum beam gains 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 lower than -8.73 dB. Figure 11b This is the beam scanning of the metasurface antenna at the 13.0 GHz frequency. When the scanning angles are 0°, 15°, 30°, 45°, and 60°, the corresponding maximum beam gains 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 lower than -9.13 dB. Figure 11cFor the beam scanning case of the metasurface antenna at 16.0 GHz frequency point, the corresponding maximum beam gains of the 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, the scanning gain loss is 2.76 dB, and the maximum sidelobe level of scanning is lower than -9.13 dB; within the 3 dB scanning loss range, the metasurface antenna can realize large-angle beam scanning of 0-60° and has good beam directivity. The results show that at 11.0 GHz (low frequency), 13.0 GHz (medium frequency) and 16.0 GHz (high frequency) three characteristic frequency points, the metasurface antenna all exhibits good scanning performance, verifying that it has excellent wideband beam steering ability within the entire working frequency band.

[0062] Figure 11d For the beam scanning pattern of the metasurface antenna at 13.0 GHz when the left-handed circularly polarized wave is incident, the corresponding maximum beam gains of the 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, the scanning gain loss is 2.39 dB, and the maximum sidelobe level of scanning is lower than -10.39 dB; Figure 11e For the change of the axial ratio in the left-handed circularly polarized beam scanning process, within the 0-60° scanning range of the circularly polarized beam, the axial ratio of the metasurface antenna always remains within 3 dB, the 3 dB axial ratio beam width is not less than 15°, and the maximum can be expanded to a scanning angle of 75°; Figure 11f For the axial ratio of the left-handed circularly polarized main beam in the working frequency band of 10.0-17.0 GHz, the axial ratio of the circularly polarized wave within the frequency band of 10.5-17.0 GHz is less than 1.5 dB; Figure 11d , Figure 11e and Figure 11f It can be seen that the metasurface antenna proposed in the application has wideband large-angle beam scanning capability under the left-handed circularly polarized beam, and combined with the multi-polarization compatible characteristics of the metasurface antenna, the metasurface antenna proposed in the application can also realize wideband large-angle beam scanning under the right-handed circularly polarized beam.

[0063] Figure 12a and Figure 12bThe gain and aperture efficiency of the main beam of the metasurface antenna in the working frequency band of 10.0-17.0 GHz are shown in the figure. As can be seen from the figure, the 3dB gain bandwidth of the metasurface antenna covers 11.0-17.0 GHz, and the relative bandwidth reaches 42.86%. The aperture efficiency is better than 13% in the entire working frequency band, and the aperture efficiency peak of 21.17% is obtained at 12.0 GHz, and the gain peak of 18.72 dB is reached at 16.0 GHz. It shows a high aperture efficiency in a wide frequency band, indicating that the metasurface antenna has good wide-band radiation characteristics.

[0064] In summary, the metasurface antenna proposed in this invention utilizes a simple structure and a highly central rotationally symmetric design to achieve a stable phase difference of 180°±30° within the metasurface unit within the 10.0-17.0 GHz range. The phase control relative bandwidth reaches up to 51.85%, and the reflection loss is less than 1.53 dB. Within the ultra-wide operating frequency band, it not only maintains a 3dB gain bandwidth of 42.86% (11.0-17.0 GHz) and an aperture efficiency exceeding 13% across the entire frequency band, but also exhibits polarization insensitivity and 60° wide-angle beam scanning capability, achieving a peak aperture efficiency of 21.17%. Furthermore, it consistently maintains excellent circular polarization characteristics with an axial ratio within 3dB during circularly polarized beam scanning. The proposed metasurface antenna exhibits significant advantages in wideband operation, multi-polarization compatibility, and wide-angle beam steering, providing an ideal technical solution for the next generation of intelligent beamforming systems. It holds significant engineering value in high-frequency applications such as satellite communications and radar detection.

Claims

1. A broadband polarization-insensitive 1-bit electrically programmable metasurface antenna, comprising an electrically programmable metasurface (2) and a feed horn (1), characterized in that: The electrically controlled programmable metasurface (2) comprises M×N periodically arranged metasurface units (4), wherein the metasurface unit (4) comprises 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) coaxially stacked from top to bottom; a metallized through hole (48) is provided at the center of the metasurface unit (4), the metallized through hole (48) vertically penetrates all high-frequency dielectric substrates and prepreg layers (44) and connects all metal layers except the metal layer 2 (43); metallized blind holes (49) are provided around the periphery of the metasurface unit (4), the metallized blind holes (49) vertically penetrate the high-frequency dielectric substrate 1 (42) and connect the metal layer 1 (41) and the metal layer 2 (43); and four parallel PIN diodes (413) are provided on the metal layer 1 (41) for regulating the reflection phase response of the metasurface unit (4).

2. The broadband polarization-insensitive 1-bit electrically programmable metasurface antenna according to claim 1, characterized in that: The metal layer (41) is distributed in a central rotationally symmetrical manner and includes four metal radiation patches (411) located on a high-frequency dielectric substrate (42). A cross-shaped metal connection bridge (412) is provided in the middle of the four metal radiation patches (411). The metal connection bridge (412) is connected to the four metal radiation patches (411) through four PIN diodes (413) to form a parallel equivalent circuit structure.

3. The broadband polarization-insensitive 1-bit electrically programmable metasurface antenna according to claim 2, characterized in that: The metal radiation patch (411) comprises a square metal patch (4111) and two L-shaped metal branches (4112) connected to the edge of the square metal patch (4111), the L-shaped metal branches (4112) comprising long branches and short branches connected vertically, the long branches of the two L-shaped metal branches (4112) being connected to each other, the short branches both facing the metal connection bridge (412), and a certain interval being provided between the short branches and the square metal patch (4111); a square annular groove (4113) is provided on the square metal patch 4111, the square annular groove (4113) being provided with a notch (4114) facing the metal connection bridge (412); 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 a corresponding side of the square annular groove (4113).

4. The broadband polarization-insensitive 1-bit electrically programmable metasurface antenna according to claim 2, 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); M×N DC bias traces (471) constitute a DC bias network structure of the electrically controlled programmable metasurface (2).

5. The broadband polarization-insensitive 1-bit electrically programmable metasurface antenna according to claim 4, characterized in that: An isolation hole (431) surrounding the metallized through hole (48) is etched on the metal layer, and the isolation hole (431) has a diameter greater than the diameter of the metallized through hole (48).

6. The broadband polarization-insensitive 1-bit electrically programmable metasurface antenna according to claim 4, characterized in that: The metal radiation patch (411) is connected to the metal ground layer via a metalized blind hole (49), the metal radiation patch (411) is connected to the metal connection bridge (412) via a PIN diode (413), and the metal connection bridge (412) is connected to a DC bias trace (471) via a metalized through hole (48), synchronously providing a bias voltage to the four parallel PIN diodes (413).

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

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

9. The broadband polarization-insensitive 1-bit electrically programmable metasurface antenna according to claim 1, characterized in that: The high-frequency dielectric substrate 1 (42) and the high-frequency dielectric substrate 2 (46) are both F4B type high-frequency dielectric substrates or Rogers type high-frequency dielectric substrates.

10. The broadband polarization-insensitive 1-bit electrically programmable metasurface antenna according to claim 1, characterized in that: According to the phase compensation formula, the The compensation phase theoretically required by each metasurface unit (4) is quantized according to a 1-bit phase quantization criterion, and the on / off of the PIN diode (413) corresponding to the metasurface unit (4) is controlled based on the discrete phase distribution after quantization.

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