A 1-bit reconfigurable reflective array antenna working in Ku band and a design method thereof

Abstract

The application discloses a 1-bit reconfigurable reflective array antenna working in a Ku band and a design method thereof, relates to the technical field of reconfigurable reflective array antennas, and aims to solve the problems of bandwidth limitation and difficulty in adapting a phase shift structure for a single-layer multi-resonance structure in the prior art. The antenna comprises a reflective array composed of reconfigurable reflective array units and a feed source fixed at a focal point of the reflective array. The reconfigurable reflective array unit comprises a three-layer differential-thickness substrate stacking structure. A rectangular radiation patch is arranged on the upper surface of a first substrate, a fractal slot patch combined with a first-order quasi-Minkowski fractal structure is arranged on the upper surface of a second substrate, and a metal ground plane is arranged on the upper surface of a third substrate, and a first microstrip line and a direct-current bias line are arranged on the lower surface of the third substrate. The direct-current bias line is composed of a quarter-wavelength microstrip line and a second microstrip line connected together. A fan-shaped opening stub is connected to the quarter-wavelength microstrip line. The rectangular radiation patch and the fractal slot patch are connected in series to a PIN diode and the direct-current bias line through a metallized via.

Description

Technical Field

[0001] This application relates to the field of reconfigurable reflective array antenna technology, and in particular to a 1-bit reconfigurable reflective array antenna operating in the Ku band and its design method. Background Technology

[0002] The demand for high-gain, real-time beamforming antennas continues to grow in the satellite communications and 6G mobile communications fields. Reconfigurable reflective array antennas have become an important technical solution due to their advantages such as eliminating the need for T / R components, low loss, and low control complexity. However, bandwidth limitation remains the main bottleneck in the design of such antennas. For small to medium-scale reconfigurable reflective array antennas, the operating bandwidth of the array elements directly limits the overall gain bandwidth.

[0003] Existing methods for extending the bandwidth of array elements mainly include single-layer multi-resonant structures and multi-layer stacked structures. Single-layer multi-resonant structures face difficulties in adapting phase-shifting structures and lumped element connections, increasing design and fabrication complexity. While multi-layer stacked structures can achieve multi-resonance through interlayer coupling, existing solutions often employ equal-thickness substrates for each layer, resulting in suboptimal resonant point distribution and limited bandwidth extension. Furthermore, the higher operating frequency in the Ku band significantly increases insertion loss introduced by lumped elements (such as PIN diodes), further restricting antenna performance. In beam-scanning applications, existing solutions often employ positive feed, which suffers from feed source obstruction, affecting aperture efficiency and gain performance. Therefore, a reconfigurable reflective array antenna technology that achieves wide bandwidth operation, low insertion loss, high aperture efficiency, and a simplified structure in the Ku band is needed. Summary of the Invention

[0004] The purpose of this invention is to provide a 1-bit reconfigurable reflective array antenna operating in the Ku band and its design method, so as to solve the problems of limited bandwidth of reconfigurable reflective array antenna elements, difficulty in adapting single-layer multi-resonant structures to phase-shifting structures and lumped elements, and large reflection loss introduced by lumped elements in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A 1-bit reconfigurable reflective array antenna operating in the Ku-band includes a reflective array and a feed source. The reflective array is composed of M×N periodically arranged reconfigurable reflective array elements, where M≥2 and N≥2. Each reconfigurable reflective array element includes a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate stacked sequentially from top to bottom. The first, second, and third dielectric substrates are designed with differentiated thicknesses, where the thickness of the first dielectric substrate is greater than that of the second dielectric substrate, and the thickness of the second dielectric substrate is greater than that of the third dielectric substrate. The upper part of the first dielectric substrate... The surface of the first substrate is provided with a rectangular radiating patch; the upper surface of the second dielectric substrate is provided with a fractal slotted patch, which adopts a hexagonal slot combined with a first-order quasi-Minkowski fractal structure; the upper surface of the third dielectric substrate is provided with a metal ground plane, and the lower surface is provided with a first microstrip line and a DC bias line. A PIN diode is loaded in the middle gap of the first microstrip line. The DC bias line is composed of a quarter-wavelength microstrip line and a second microstrip line connected together. The DC bias line, radial stub, microstrip line and PIN diode are provided. The radial stub is electrically connected to the DC bias line. The quarter-wavelength microstrip line... The upper part is connected with a short stub with a fan-shaped opening; each of the reconfigurable reflective array units is provided with only one PIN diode, which is placed below the back metal ground plane of the third dielectric substrate, and its two ends are electrically connected to the two ends of the first microstrip line respectively; the reconfigurable reflective array unit is provided with at least two metal vias that penetrate through three dielectric substrates and are connected to the rectangular radiating patch and the fractal slotted patch. The metal vias penetrate the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate, and the top end of one of the metal vias is electrically connected to the rectangular radiating patch and the fractal slotted patch, and the bottom end is electrically connected to the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate. One end is electrically connected to one end of the first microstrip line, and the top end of another metal via is electrically connected to the rectangular radiating patch and the fractal slotted patch, while the bottom end is electrically connected to the DC bias line; the metal ground plane and the other end of the microstrip line are connected through a metallized via; by controlling the on and off states of the PIN diode, the resonant characteristics of the reconfigurable reflective array unit are changed, achieving a 180° phase difference between the two operating states; the feed source uses a linearly polarized standard pyramidal horn antenna for bias feeding, and the biased horn antenna is placed in the XoZ plane with a bias angle relative to the center of the reflective array.

[0006] As a preferred embodiment, the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate can all be made of Arlon AD255 substrate, which has a dielectric constant of 2.55.

[0007] As a preferred embodiment, the thickness of the first dielectric substrate can be 1.225 mm, the thickness of the second dielectric substrate can be 1.056 mm, and the thickness of the third dielectric substrate can be 0.508 mm.

[0008] As a preferred embodiment, an adhesive sheet with a thickness of 0.22 mm can be provided between the first dielectric substrate and the second dielectric substrate, and an adhesive sheet with a thickness of 0.22 mm can be provided between the second dielectric substrate and the third dielectric substrate, and the substrate is fixed by pressing together with the adhesive sheet.

[0009] As a preferred embodiment, the fractal slotted patch includes a hexagonal slot and a first-order quasi-Minkowski fractal structure. The hexagonal slot can be located at the center of the fractal slotted patch, and the first-order quasi-Minkowski fractal structure is distributed along the edge of the fractal slotted patch.

[0010] As a preferred embodiment, the rectangular radiating patch can have a length L1 of 4.5 mm and a width W1 of 4.5 mm, the fractal slotted patch can have a length L2 of 4.5 mm and a width W2 of 4.5 mm, and the radius r3 of the hexagonal slot can be 0.69 mm.

[0011] As a preferred embodiment, the period P of the reconfigurable reflective array unit is 9.89 mm.

[0012] As a preferred embodiment, the width w of the microstrip line s It can be 0.2mm.

[0013] As a preferred embodiment, the diameter r1 of the metal via can be 1 mm, and the diameter r2 of the metal via connecting the microstrip line can be 0.4 mm.

[0014] As a preferred embodiment, M=20, N=20, and the offset angle of the linearly polarized standard pyramidal horn antenna can be 25°.

[0015] A design method for a 1-bit reconfigurable reflective array antenna operating in the Ku band includes the following steps: Step 1, array antenna element structure design: An Arlon AD255 substrate with a dielectric constant of 2.55 is selected as the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate. The thickness of the first dielectric substrate is 1.225 mm, the thickness of the second dielectric substrate is 1.056 mm, and the thickness of the third dielectric substrate is 0 mm.508mm; A rectangular radiating patch is disposed on the upper surface of the first dielectric substrate, and a fractal slotted patch is disposed on the upper surface of the second dielectric substrate. The fractal slotted patch adopts a hexagonal slot combined with a first-order quasi-Minkowski fractal structure. A metal ground plane is disposed on the upper surface of the third dielectric substrate, and a first microstrip line and a DC bias line are disposed on the lower surface. A PIN diode is loaded in the middle gap of the first microstrip line. The DC bias line is composed of a quarter-wavelength microstrip line and a second microstrip line connected together. The DC bias line, radial stub, microstrip line, and PIN diode are present. The radial stub is electrically connected to the DC bias line. A fan-shaped opening stub is connected to the quarter-wavelength microstrip line. Each reconfigurable reflective array unit is provided with only one PIN diode. The PIN diode is placed below the back metal ground plane of the third dielectric substrate, and its two ends are electrically connected to the two ends of the first microstrip line, respectively. Two metal ground planes are disposed on the reconfigurable reflective array unit, penetrating the three dielectric substrates and connected to the rectangular radiating patch and the fractal slotted patch. Vias, the metal vias penetrate the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate. The top end of one metal via is electrically connected to the rectangular radiating patch and the fractal slotted patch, and the bottom end is electrically connected to one end of the first microstrip line. The top end of the other metal via is electrically connected to the rectangular radiating patch and the fractal slotted patch, and the bottom end is electrically connected to the DC bias line. The metal ground plane and the other end of the microstrip line are connected through metallized vias. Step two, construction of the M×N array antenna: The optimized array elements are arranged in an M x N rectangular pattern. The array arrangement follows a 0 / 1 two-dimensional table obtained from phase compensation calculation. The phase compensation calculation is based on the target beam scanning angle. The on or off state of the PIN diode is determined by calculating the required reflection phase of each array element. A linearly polarized standard pyramidal horn antenna is used as the feed source for bias feeding. The biased horn antenna is placed in the XoZ plane with a bias angle of 25° to reduce the blocking effect. Step three, electromagnetic simulation verification: CST is used. Studio Suite models the array elements and reconfigurable reflective array antenna, analyzing the reflection coefficient and radiation pattern. Step four, results analysis and performance summary: The analysis shows that the three-layer differential thickness substrate stacking structure breaks the symmetrical electromagnetic coupling limitation of the traditional equal-thickness stacking structure, promoting resonance fusion of adjacent resonant frequencies, thereby expanding the relative operating bandwidth. The hexagonal slots remove the central region where the current is most concentrated, diverting the surface current to the edge fractal structure. The non-right-angle smooth transition of the edge fractal structure and the obtuse angle characteristics of the hexagon eliminate the abrupt changes in parasitic capacitance and inductance caused by the traditional square right-angle structure, thus making the surface current path of the element highly continuous and ensuring that the curve of the reflection phase changing with frequency exhibits good smoothness.

[0016] As a preferred embodiment, in step one, the length L1 of the rectangular radiating patch can be 4.5 mm and the width W1 can be 4.5 mm, the length L2 of the fractal slotted patch can be 4.5 mm and the width W2 can be 4.5 mm, the radius r3 of the hexagonal slot can be 0.69 mm, and the period P of the reconfigurable reflective array unit can be 9.89 mm.

[0017] As a preferred embodiment, in step two, the array elements are arranged according to the 0 / 1 two-dimensional table obtained by phase compensation calculation using Matlab code, with M=20, N=20, and the overall size is 197.8mm×197.8mm. The offset angle of the offset horn antenna can be 25°.

[0018] The beneficial effects of this invention are: (1) By adopting a three-layer differential thickness substrate stacking structure (first substrate 1.225mm, second substrate 1.056mm, third substrate 0.508mm), the three-layer differential thickness substrate stacking structure breaks the symmetrical electromagnetic coupling limitation of the traditional equal thickness stacking structure, promotes the resonance fusion of adjacent resonant frequencies, thereby expanding the relative working bandwidth. The insertion loss is less than 1dB in both working states. In the working frequency range of 13.1GHz to 17.9GHz, the relative working bandwidth reaches 31%, which is significantly better than the existing technology. (2) The fractal slotted patch on the front side of the second substrate adopts a combination of hexagonal slotting and first-order quasi-Minkowski fractal structure. The hexagonal slotting removes the central area where the current is most concentrated and diverts the surface current to the edge fractal structure. The non-right-angle smooth transition of the edge fractal structure and the obtuse angle characteristics of the hexagon eliminate the abrupt changes in parasitic capacitance and parasitic inductance caused by the traditional square right-angle structure. This makes the surface current path of the unit highly continuous and ensures that the curve of the reflection phase changing with frequency shows good smoothness, thus solving the problem that single-layer multi-resonant structure is difficult to adapt to phase-shifting structure. (3) Each array unit requires only one PIN diode, and the PIN diode is placed below the ground plane of the third substrate. By controlling its on and off states, the unit resonance characteristics are changed, achieving a 180° phase difference between the two states. This simplifies the unit structure, reduces control complexity and cost, and reduces interference to the antenna reflection phase and amplitude without affecting the array arrangement and beam illumination on the front. (4) The linearly polarized standard pyramidal horn antenna is fed by placing the horn in the XoZ plane with an offset angle of 25°, which reduces the blocking effect and improves the antenna radiation efficiency. The 20×20 reconfigurable reflective array antenna designed based on this unit has a beam scanning range of -30° to 60°, a peak aperture efficiency of 24.66% at the center frequency of 15.5GHz, and a maximum gain of 25.11dBi. The Ku-band digital signal transmission stability is better than that of the C-band, making it more suitable for satellite digital broadcasting applications. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the reconfigurable reflective array unit of the present invention.

[0020] Figure 2 This is a side view of the reconfigurable reflective array unit of the present invention.

[0021] Figure 3 This is a schematic diagram of the structure of the 1-bit reconfigurable reflective array antenna of the present invention.

[0022] Figure 4 This is a simulated reflection coefficient curve of the reconfigurable reflective array unit of the present invention under vertical incidence.

[0023] Figure 5 This is a simulated reflection coefficient curve of the reconfigurable reflective array unit of the present invention under oblique incidence.

[0024] Figure 6 This is the normalized radiation pattern of the XOZ plane of the reconfigurable reflective array antenna of the present invention at a center frequency of 15.5 GHz.

[0025] Figure 1 In the middle: 1. Rectangular radiating patch; 2. First substrate; 3. Fractal slotted patch; 4. Second substrate; 5. Ground plane; 6. Third substrate; 7. Metal via; 8. First microstrip line; 9. DC bias line; 10. PIN diode. Detailed Implementation

[0026] This invention provides a single-position reconfigurable reflective array antenna operating in the Ku-band and its design method. By employing a three-layer stacked substrate structure with varying thicknesses, a metal patch with hexagonal slots combined with a first-order quasi-Minkowski fractal structure is placed on the upper surface of the second substrate. Multiple adjacent resonant frequencies are formed through inter-layer coupling, achieving resonance fusion and effectively expanding the operating bandwidth. Simultaneously, PIN diodes are placed on the lower surface of the third substrate. By controlling their on / off states, the resonant characteristics of the unit are altered, achieving a phase difference of 180°±20°. Each unit requires only one PIN diode, simplifying the control structure. This antenna achieves a relative operating bandwidth of 31% in the 13.1GHz to 17.9GHz range, with an insertion loss of less than 1dB, a beam scanning range of -30° to 60°, a peak aperture efficiency of 24.66% at a center frequency of 15.5GHz, and a maximum gain of 25.11dBi. This invention solves the technical problems of limited bandwidth and the difficulty in adapting single-layer multi-resonant structures to phase-shifting structures in existing reconfigurable reflective array antennas.

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1 like Figure 1 and Figure 2 As shown, this embodiment provides a complete structure for a 1-bit reconfigurable reflective array unit operating in the Ku band.

[0029] The unit comprises three dielectric substrates stacked sequentially from top to bottom: a first substrate 2, a second substrate 4, and a third substrate 6. All three substrates are made of Arlon AD255 substrate with a dielectric constant of 2.55.

[0030] Each substrate layer adopts a differentiated thickness design: the thickness h1 of the first substrate 2 is 1.225mm, the thickness h2 of the second substrate 4 is 1.056mm, and the thickness h3 of the third substrate 6 is 0.508mm.

[0031] A 0.22mm thick adhesive sheet is provided between the first substrate 2 and the second substrate 4 for pressing and fixing. Similarly, a 0.22mm thick adhesive sheet is provided between the second substrate 4 and the third substrate 6 for pressing and fixing.

[0032] A rectangular radial patch 1 is disposed on the upper surface of the first substrate 2. The patch has a length L1 of 4.5 mm and a width W1 of 4.5 mm. The rectangular radial patch 1 and the first substrate 2 are integrated together by a printed circuit etching process.

[0033] The upper surface of the second substrate 4 is provided with a fractal slotted patch 3, the patch having a length L2 of 4.5 mm and a width W2 of 4.5 mm. The fractal slotted patch 3 adopts a hexagonal slot combined with a first-order quasi-Minkowski fractal structure.

[0034] The hexagonal slot is located at the center of the fractal slotted patch 3, with a radius r3 of 0.69 mm. The hexagonal slot optimizes the current path and adjusts the resonant parameters.

[0035] The first-order quasi-Minkowski fractal structure is distributed along the edge of the fractal slotted patch 3. The hexagonal slots remove the central region where the current is most concentrated, diverting the surface current to the edge fractal structure. The non-right-angle smooth transition of the edge fractal structure and the obtuse angle characteristics of the hexagon eliminate the abrupt changes in parasitic capacitance and inductance caused by the traditional square right-angle structure. This makes the surface current path of the cell highly continuous, ensuring that the curve of the reflection phase changing with frequency exhibits good smoothness. The fractal slotted patch 3 and the second substrate 4 are integrated into one piece through a printed circuit etching process.

[0036] The upper surface of the third substrate 6 is provided with a metal ground plane 5, and the lower surface is provided with a first microstrip line 8, a DC bias line 9, a fan-shaped stub line and a PIN diode 10.

[0037] The width w of the first microstrip line 8 s The diameter is 0.2mm, and the two ends are connected to the two ends of PIN diode 10 respectively. The fan-shaped stub is electrically connected to DC bias line 9 to isolate DC signals.

[0038] The PIN diode 10 is placed on the lower surface of the third substrate 6 and fixed by a printed circuit process (such as etching followed by soldering). Only one PIN diode 10 is provided in each array unit.

[0039] The unit has three metal vias 7, two of which penetrate the first substrate 2, the second substrate 4, and the third substrate 6. One metal via is electrically connected at its top to the rectangular radiating patch 1 and the fractal slotted patch 3, and at its bottom to one end of the first microstrip line 8. The other metal via is electrically connected at its top to the rectangular radiating patch 1 and the fractal slotted patch 3, and at its bottom to one end of the DC bias line. The diameter r4 of the metal vias is 0.3 mm. Figure 1 In the diagram, r1 and r2 are the diameters of the isolation holes, used to prevent short circuits caused by contact between the metal vias and the metal ground plane.

[0040] Another metal via 7 has its top end electrically connected to the ground plane 5 and its bottom end electrically connected to the other end of the first bias line 8. The diameter r4 of the metal via is 0.3 mm.

[0041] The period P of the element is 9.89 mm, meaning that the length and width of the element are both 9.89 mm.

[0042] The working principle is as follows: When the incident electromagnetic wave irradiates the array unit, the first layer rectangular radiating patch 1 and the second layer fractal slotted patch 3 are coupled to generate multiple resonant frequencies.

[0043] By controlling the on and off states of PIN diode 10, the equivalent circuit resonant frequency of the unit is changed, thereby altering the resonant characteristics of the unit.

[0044] When PIN diode 10 is turned on, the unit exhibits a first resonant state; when PIN diode 10 is turned off, the unit exhibits a second resonant state. The reflection phase difference between the two states reaches 180°±20°.

[0045] Technical effect: Due to the use of a three-layer differential thickness substrate stack structure (h1=1.225mm, h2=1.056mm, h3=0.508mm), multiple resonant points with adjacent resonant frequencies are formed through the coupling between layers, thus achieving resonance fusion.

[0046] Because the second substrate uses a fractal slot patch with a hexagonal slot combined with a first-order quasi-Minkowski fractal structure on the front side, the hexagonal slot optimizes the current path, and the fractal structure excites multiple adjacent resonant frequencies, enhancing the multi-resonance characteristics.

[0047] Because the PIN diodes are placed below the ground plane of the third substrate, interference with the antenna reflection phase and amplitude is reduced, and the array arrangement and beam illumination on the front are not affected.

[0048] Since each unit requires only one PIN diode, the unit structure is simplified, and the control complexity and cost are reduced.

[0049] Based on the above technical features, this unit has an insertion loss of less than 1dB and a relative operating bandwidth of 31% in the operating frequency range of 13.1GHz to 17.9GHz, and the phase difference between the two states is stable at 180°±20°.

[0050] Example 2 like Figure 3 As shown, this embodiment provides a 20×20 reconfigurable reflective array antenna system.

[0051] The system consists of 400 array units as described in Embodiment 1, arranged periodically in a rectangular pattern of 20 rows × 20 columns, with an overall size of 197.8 mm × 197.8 mm.

[0052] The horn feed Figure 3 (2) A 12GHz-18GHz standard linearly polarized pyramidal horn antenna is used, with its equivalent phase center located above the reflector array surface. In this embodiment, the distance from the standard pyramidal horn antenna to the array surface is 196.42mm, the offset angle is 25°, and the corresponding focal diameter ratio is 0.9.

[0053] The array elements are arranged strictly according to the 0 / 1 two-dimensional table obtained from the phase compensation calculation. The phase compensation calculation is based on the target beam scanning angle. By calculating the required reflection phase for each array element, the on or off state of the corresponding element's PIN diode is determined.

[0054] The array is arranged using Matlab code, generating a 0 / 1 two-dimensional table, where "0" indicates that the PIN diode of the corresponding unit is off, and "1" indicates that the PIN diode of the corresponding unit is on.

[0055] The system uses a linearly polarized standard pyramidal horn antenna as its feed source. The feed source is positioned in the XoZ plane and offset at a 25° angle relative to the center of the reflector array to reduce the blocking effect.

[0056] The offset-fed horn antenna operates in the frequency range of 12 GHz to 18 GHz, matching the operating frequency band of the array elements. The distance from the feed to the center of the reflector is determined based on the focal diameter ratio design.

[0057] The main control circuit board controls the on / off state of the PIN diodes in each unit, and adjusts different phase arrangements to achieve beam scanning functions at different angles.

[0058] Technical Results: This 20×20 reconfigurable reflective array antenna achieves a beam scanning range of -30° to 30°. At a center frequency of 15.5 GHz, it achieves a peak aperture efficiency of 24.66% and a maximum gain of 25.11 dBi.

[0059] Because of the offset feeding method, the horn antenna is placed in the XoZ plane with an offset angle of 25°, which effectively reduces the blocking effect and improves the antenna radiation efficiency.

[0060] Example 3 This embodiment describes the electromagnetic simulation verification process.

[0061] Simulation tools: CST Studio Suite was used to model the array element described in Example 1 and the reconfigurable reflective array antenna described in Example 2.

[0062] Simulation boundary conditions: Periodic boundary conditions (Floquet port) are applied to individual array elements to simulate an infinite array environment. The frequency sweep range is 12GHz to 18GHz, with a step of 0.1GHz.

[0063] Simulation results for perpendicular incidence (0°): (e.g.) Figure 4 As shown, within the operating frequency range of 13.1 GHz to 17.9 GHz, the reflection coefficient of the array cells in both the ON state (PIN diode on) and OFF state (PIN diode off) is less than -10 dB.

[0064] The reflection phase difference between the ON and OFF states remains stable at 180°±20°. The insertion loss is less than 1dB, and the relative operating bandwidth reaches 31%.

[0065] Oblique incidence simulation results: such as Figure 5 As shown, the reflection phase difference curves of the array elements highly coincide under the three conditions of incident angles of 0°, 10°, and 20°.

[0066] Within the 13.1 GHz to 17.9 GHz range, the phase difference between the ON and OFF states under all three incident angles remained stable at 180° ± 20°, indicating that the unit has good angular stability.

[0067] Array radiation pattern simulation: such as Figure 6 As shown, the radiation pattern of a 20×20 reconfigurable reflective array antenna at a center frequency of 15.5 GHz is simulated.

[0068] By adjusting the state of the PIN diodes in each unit, normalized XOZ radiation patterns with seven beam scanning angles (θ=0°, θ=15°, θ=-15°, θ=30°, θ=-30°, θ=45°, and θ=60°) were achieved.

[0069] Simulation results show that the beam scanning range of the array antenna is -30° to 60°, and the sidelobe electrical average is less than -10dB at each scanning angle.

[0070] At a center frequency of 15.5 GHz and θ = -15°, the peak aperture efficiency is 24.66% and the maximum gain is 25.11 dBi.

[0071] Example 4 This embodiment compares the performance of the present invention with that of the prior art document CN113113774A.

[0072] Prior art document CN113113774A discloses a broadband beam scanning reflective array antenna, which adopts a three-layer dielectric substrate stacked structure. The first layer is provided with a square radiating patch, the second layer is provided with two circular radiating patches, and the third layer is provided with a reflective ground plane and a DC bias line.

[0073] In comparison document CN113113774A, the first and second substrates have equal thicknesses, employing an equal-thickness design. Both its square radiating patch and the two bilateral annular radiating patches are of regular geometric shapes, without employing a fractal geometric design.

[0074] The performance comparison is as follows: Operating bandwidth: The operating frequency range of this invention is 13.1 GHz to 17.9 GHz, representing a relative operating bandwidth of 31%. The relative bandwidth of prior art document CN113113774A is approximately 24.5%. This invention represents a bandwidth improvement of approximately 27%.

[0075] Peak aperture efficiency: This invention achieves a peak aperture efficiency of 24.66% at a center frequency of 15.5 GHz. The peak aperture efficiency of prior art document CN113113774A is approximately 23.8%. This invention demonstrates a significant improvement in aperture efficiency. It should be noted that there is a certain trade-off between aperture efficiency and performance indicators such as beam scanning range and bandwidth. This invention significantly outperforms the prior art in terms of bandwidth and beam scanning range, while the slightly lower aperture efficiency is within a reasonable range.

[0076] Maximum gain: The maximum gain of this invention is 25.11 dBi at the center frequency of 15.5 GHz. The maximum gain of the comparative document CN113113774A is about 24.31 dBi, so the maximum gain of this invention is slightly improved.

[0077] Number of PIN diodes per unit: This invention requires only one PIN diode per unit, and the PIN diode is placed below the ground plane, which reduces interference with the reflection phase and amplitude.

[0078] Technical Effect Analysis: This invention employs a fractal slotted patch combining hexagonal slots with a first-order quasi-Minkowski fractal structure. The hexagonal slots eliminate the central region where current is most concentrated, diverting surface current to the edge fractal structure. The non-right-angle smooth transition of the edge fractal structure and the obtuse angle of the hexagon eliminate the abrupt changes in parasitic capacitance and inductance caused by traditional square right-angle structures, thus ensuring a highly continuous surface current path for the unit and guaranteeing a smooth curve of the reflection phase changing with frequency. Simultaneously, by using a three-layer differential thickness substrate stack structure (h1=1.225mm, h2=1.056mm, h3=0.508mm), the symmetrical electromagnetic coupling limitation of traditional equal-thickness stack structures is broken, promoting resonance fusion between adjacent resonant frequencies and thus expanding the relative operating bandwidth. The synergistic effect of the fractal structure and differential thickness stack makes the unit's reflection phase curve smoother, effectively expanding the operating bandwidth to 31%, solving the problem of single-layer multi-resonant structures being difficult to adapt to phase-shifting structures.

[0079] The effect of this technology is unexpected and significantly superior to existing technologies.

[0080] Those skilled in the art should understand that the above embodiments are for illustrative purposes only and are not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A 1-bit reconfigurable reflective array antenna operating in the Ku-band, characterized in that, It includes a reflective array and a feed source. The reflective array consists of M×N periodically arranged reconfigurable reflective array units, where M≥2 and N≥2. The reconfigurable reflective array unit includes a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate stacked sequentially from top to bottom. The first, second, and third dielectric substrates employ a differentiated thickness design, with the first substrate being thicker than the second substrate, and the second substrate being thicker than the third substrate. A rectangular radiating patch is disposed on the upper surface of the first substrate. A fractal slotted patch is disposed on the upper surface of the second substrate, employing a hexagonal slot combined with a first-order quasi-Minkowski fractal structure. A metal ground plane is disposed on the upper surface of the third substrate, and a first microstrip line and a DC bias line are disposed on the lower surface. A PIN diode is loaded at the gap in the middle of the first microstrip line. The DC bias line is composed of a quarter-wavelength microstrip line and a second microstrip line connected together, with a fan-shaped stub connected to the quarter-wavelength microstrip line. Each reconfigurable reflective array unit is provided with only one PIN diode, which is placed on the third substrate. The lower surface of the substrate has its two ends electrically connected to the two ends of the first microstrip line, respectively. The reconfigurable reflective array unit has two metal vias penetrating the three dielectric substrates and connected to a rectangular radiating patch and a fractal slotted patch. The top end of one metal via is electrically connected to the rectangular radiating patch and the fractal slotted patch, and the bottom end is electrically connected to one end of the first microstrip line. The top end of the other metal via is electrically connected to the rectangular radiating patch and the fractal slotted patch, and the bottom end is electrically connected to the DC bias line. The metal ground plane and the other end of the microstrip line are connected through a metallized via. By controlling the on and off states of the PIN diode, the resonant characteristics of the reconfigurable reflective array unit are changed, achieving a 180° phase difference between the two operating states. The feed source uses a linearly polarized standard pyramidal horn antenna, which is placed in the XoZ plane and has a bias angle relative to the center of the reflective array.

2. The 1-bit reconfigurable reflective array antenna operating in the Ku-band according to claim 1, characterized in that, The first dielectric substrate, the second dielectric substrate, and the third dielectric substrate are all made of Arlon AD255 substrate with a dielectric constant of 2.

55.

3. The 1-bit reconfigurable reflective array antenna operating in the Ku band according to claim 2, characterized in that, The thickness of the first dielectric substrate is 1.225 mm, the thickness of the second dielectric substrate is 1.056 mm, and the thickness of the third dielectric substrate is 0.508 mm.

4. The 1-bit reconfigurable reflective array antenna operating in the Ku band according to claim 3, characterized in that, An adhesive sheet with a thickness of 0.22 mm is disposed between the first dielectric substrate and the second dielectric substrate, and an adhesive sheet with a thickness of 0.22 mm is disposed between the second dielectric substrate and the third dielectric substrate, and the substrate is fixed by pressing together with the adhesive sheet.

5. The 1-bit reconfigurable reflective array antenna operating in the Ku-band according to claim 1, characterized in that, The fractal slotted patch includes a hexagonal slot and a first-order quasi-Minkowski fractal structure. The hexagonal slot is located at the center of the fractal slotted patch, and the first-order quasi-Minkowski fractal structure is distributed along the edge of the fractal slotted patch.

6. The 1-bit reconfigurable reflective array antenna operating in the Ku-band according to claim 5, characterized in that, The rectangular radiating patch has a length L1 of 4.5 mm and a width W1 of 4.5 mm, the fractal slotted patch has a length L2 of 4.5 mm and a width W2 of 4.5 mm, and the radius r3 of the hexagonal slot is 0.69 mm.

7. The 1-bit reconfigurable reflective array antenna operating in the Ku-band according to claim 6, characterized in that, The period P of the reconfigurable reflective array unit is 9.89 mm.

8. The 1-bit reconfigurable reflective array antenna operating in the Ku-band according to claim 1, characterized in that, The width ws of the microstrip line is 0.2 mm.

9. The 1-bit reconfigurable reflective array antenna operating in the Ku-band according to claim 1, characterized in that, The diameter r1 of the metal via is 1 mm, and the diameter r2 of the metal via connecting the microstrip line is 0.4 mm.

10. The 1-bit reconfigurable reflective array antenna operating in the Ku-band according to claim 1, characterized in that, M=20, N=20, the horn antenna feed adopts a 13.8dBi linearly polarized standard pyramidal horn with a frequency of 12GHz-18GHz, its equivalent phase center is located above the reflector array surface, the distance from the standard pyramidal horn to the array surface is 196.42mm, the corresponding focal diameter ratio is 0.9, and the offset angle of the offset horn antenna is 25°.

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