Mechanically reconfigurable real-aperture microwave radiometer polarisation-tunable metasurface reflectarray

Abstract

The application belongs to the technical field of metamaterials, and particularly relates to a mechanically reconfigurable real-aperture microwave radiometer polarization-adjustable metasurface reflection array, which comprises a plurality of periodically arrayed basic units, the basic unit comprises, from top to bottom, a top layer metal patch, a dielectric layer, a bottom layer metal plate and a rotating part which are sequentially stacked and arranged, the dielectric layer comprises a body and a cylinder sleeved in the body, the bottom layer metal plate comprises a substrate and a circular plate in the substrate, the rotating part is connected with the circular plate to drive the whole rotating of the top layer metal patch, the cylinder and the circular plate, the top layer metal patch comprises a spindle-shaped patch, a connecting rod connected with two long shaft ends of the spindle-shaped patch and a metal branch provided at the end of the connecting rod, and the metal branch is arc-shaped and faces the spindle-shaped patch, the application realizes dynamic adjustment of linear polarization mode in the C band, has high polarization conversion rate and narrow beam characteristics, has a wide effective working bandwidth, low loss and high resolution.

Description

Technical Field

[0001] This invention belongs to the field of metamaterials technology, specifically relating to a mechanically reconfigurable real-aperture microwave radiometer with tunable polarization metasurface reflector array. Background Technology

[0002] Sea surface temperature, sea surface wind field, and polar ice and snow parameters are key elements for studying global climate change, ocean dynamics, and the water cycle. Microwave radiometers, through their antennas, receive radiation naturally emitted by observed targets, thereby retrieving the targets' physical parameters. The microwave brightness temperature of a target in the C-band (around 6.9 GHz) is sensitive to changes in sea surface temperature and wind speed; therefore, microwave radiometers can be used for large-area, long-term satellite remote sensing of sea surface temperature and wind speed changes.

[0003] Microwave radiometers require high spatial resolution and high radiation measurement accuracy. To improve the accuracy of inverting parameters such as sea surface temperature and wind field, the system needs to be able to acquire dual-polarized brightness temperature data. Traditional methods for achieving polarization-tunable high-resolution observations use large parabolic antennas and complex dual-polarized feed networks, resulting in bulky, cumbersome systems with insertion loss. In recent years, reconfigurable metasurface reflectors have become a research hotspot due to their simple structure, planar design, and flexible and controllable electromagnetic properties.

[0004] Currently, most polarization-reconfigurable reflector arrays employ electronic control schemes that utilize active devices such as PIN diodes. However, microwave radiometers are highly sensitive to thermal noise, and active devices introduce high ohmic losses in the C-band (around 6.9 GHz). Furthermore, complex bias networks are prone to parasitic coupling, thereby reducing the system's radiation measurement resolution and polarization purity. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a mechanically reconfigurable real aperture microwave radiometer with a polarization-tunable metasurface reflector array, which realizes dynamic adjustment of the linear polarization mode in the C-band, and has high polarization conversion rate and narrow beam characteristics, with a wide effective working bandwidth, low loss and high resolution.

[0006] This invention provides a mechanically reconfigurable real aperture microwave radiometer with a polarization-tunable metasurface reflective array, comprising multiple periodically distributed basic units. Each basic unit includes a top metal patch, a dielectric layer, a bottom metal plate, and a rotating component stacked sequentially from top to bottom. The medium layer includes a body and a cylinder fitted inside the body, with a gap I between the body and the cylinder, and the top metal patch is located on the cylinder; The bottom metal plate includes a substrate and a circular plate located inside the substrate, and a gap II is provided between the substrate and the circular plate; The rotating component is connected to the circular plate to drive the top metal patch, cylinder and circular plate to rotate as a whole; The top metal patch includes a spindle-shaped patch, connecting rods at the two long shaft ends of the spindle-shaped patch, and metal branches at the ends of the connecting rods, wherein the metal branches are arc-shaped and face the spindle-shaped patch.

[0007] Preferably, the basic unit is a rectangle with a side length of 21mm.

[0008] Preferably, the length ratio of the major axis to the minor axis of the spindle-shaped patch is 1.4-2.6:1.

[0009] Preferably, the spindle-shaped patch is symmetrical along both the long axis and the short axis.

[0010] Preferably, the length of the connecting rod is 0.4-0.5 times the semi-major axis of the spindle-shaped patch.

[0011] Preferably, the metal branches are arranged symmetrically around the connecting rod.

[0012] Preferably, the arc shape of the metal branch is part of an arc with the center point of the spindle-shaped patch as the center, and the central angle of the metal branch is 40°-150°.

[0013] Preferably, the widths of gap I and gap II are the same.

[0014] Preferably, the rotating component includes a rotating shaft with a diameter of 1.4-2 mm.

[0015] Preferably, the dielectric layer is made of F4B, with a relative permittivity of 2.65, a loss tangent of 0.001, and a thickness of 7.5 mm.

[0016] The beneficial effects of this invention are that it achieves continuous phase compensation during array deployment by changing the angle of the top metal patch on the surface. By mechanically rotating the top metal patch by a certain angle (e.g., -45° and 45°, 0° and 90°), two different operating modes are formed. Each mode can achieve continuous phase coverage of over 360°. Switching between the two modes via mechanical rotation enables adjustable polarization of the entire reflector array. In the 5.6-8.7 GHz range, the reflection amplitude of the unit in both states is within -2 dB, resulting in low loss. Specifically, a polarization conversion efficiency of over 90% can be achieved in the 5.6-8.3 GHz range. At the target frequency, the maximum gain of the reflector array in both states is 29.7 dBi, and the 3 dB beamwidth in both the E-plane and H-plane is less than 4.3°.

[0017] This invention achieves dynamic adjustment of polarization state in the C-band, enabling the microwave radiometer system to dynamically switch between two polarization detection modes. It features high reflectivity and high polarization conversion rate, and also has the advantages of miniaturization, low cost, and ease of processing, providing a new approach for microwave radiometers to detect sea surface temperature and wind field.

[0018] This invention applies a mechanically reconfigurable reflector array operating in the C-band to a microwave radiometer antenna system. By mechanically controlling the polarization state of the control unit structure, the polarization of the entire reflector array can be adjusted, thereby replacing the high-loss active electronic control structure and complex dual-polarization feed. This enables rapid and low-loss polarization adjustment, allowing for brightness temperature measurements in different sea areas. It has broad application prospects in the future field of marine microwave remote sensing. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the basic unit of the present invention.

[0020] Figure 2 This is a top view of the basic unit of the present invention.

[0021] Figure 3 This is a side view of the basic unit of the present invention.

[0022] Figure 4 This is a rear view of the structure of the basic unit of the present invention.

[0023] Figure 5 This is the polarization conversion rate of the present invention.

[0024] Figure 6 This is the phase shift curve of the entire invention rotated by -45°.

[0025] Figure 7 This is the phase shift curve of the present invention when the entire system is rotated by 0°.

[0026] Figure 8 This is an overall schematic diagram of the present invention in working mode 1.

[0027] Figure 9 This is an overall schematic diagram of the second working mode of the present invention.

[0028] Figure 10 This is the radiation pattern of the present invention in working mode 1.

[0029] Figure 11 This is the radiation pattern of the present invention in working mode 2.

[0030] Figure 12 This is a top view of a unit in Comparative Example 1 of the present invention.

[0031] Figure 13 This is a comparison of the polarization conversion rates of Comparative Example 1 and Example 1.

[0032] Figure 14 This is a top view of a unit in Comparative Example 2 of the present invention.

[0033] Figure 15 This is a comparison of the polarization conversion rates of Comparative Example 2 and Example 1 of the present invention.

[0034] Figure 16 This is a comparison of the beam pattern of Comparative Example 3 of the present invention.

[0035] Figure 17 This is a top view of the basic unit in Comparative Example 4.

[0036] Figure 18 For comparison of polarization conversion rates between Comparative Example 4 and Example 1.

[0037] Figure 19 This is a top view of the basic unit of Comparative Example 5.

[0038] Figure 20 For comparison of polarization conversion rates between Comparative Example 5 and Example 1.

[0039] In the diagram, 1. Top metal patch; 2. Dielectric layer; 3. Bottom metal plate; 4. Rotating component; 11. Spindle-shaped patch; 12. Connecting rod; 13. Metal branch; 21. Main body; 22. Cylinder; 23. Gap I; 31. Substrate; 32. Circular plate; 33. Gap II. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention.

[0042] Example 1 A mechanically reconfigurable real-aperture microwave radiometer with a polarization-tunable metasurface reflector array, comprising multiple periodically arrayed basic units (such as... Figure 1 As shown in the figure, the basic unit includes a top metal patch 1, a dielectric layer 2, a bottom metal plate 3, and a rotating component 4, which are stacked from top to bottom. The medium layer 2 includes a body 21 and a cylinder 22 fitted inside the body 21. A gap I 23 is provided between the body 21 and the cylinder 22. The top metal patch 1 is located on the cylinder 22. The bottom metal plate 3 includes a substrate 31 and a circular plate 32 located within the substrate 31, and a gap II 33 is provided between the substrate 31 and the circular plate 32. The rotating component 4 is connected to the circular plate 32 to drive the top metal patch 1, the cylinder 22 and the circular plate 32 to rotate as a whole; The top metal patch 1 includes a spindle-shaped patch 11, a connecting rod 12 connected to the two long shaft ends of the spindle-shaped patch 11, and a metal branch 13 disposed at the end of the connecting rod 12. The metal branch 13 is arc-shaped and faces the spindle-shaped patch 11.

[0043] The basic unit is a rectangle, and the side length of the rectangle is... p It is 21mm.

[0044] The number of metal branches 13 is two, and their length and overall angle can be changed according to phase compensation requirements. The length ratio of the major axis to the minor axis of the spindle-shaped patch 11 is 1.4-2.6:1 (1.4:1 in Example 1). The spindle-shaped patch 11 is symmetrical along both its major and minor axes. The length of the connecting rod 12 is 0.4-0.5 times the semi-major axis (i.e., half of the major axis) of the spindle-shaped patch 11 (2.1 / 4.9=0.43:1 in Example 1). The arc of the metal branch 13 is part of the arc centered on the center point of the spindle-shaped patch 11, and the central angle of the metal branch 13 is 40°-150° (100° in Example 1).

[0045] like Figure 2 As shown, the top metal patch 1 includes a spindle-shaped patch 11 and two arc-shaped metal branches 13. The outer periphery of the top metal patch 1 is an air gap that runs through the entire unit structure, providing space for the rotation of the unit structure. After simulation optimization, the dimensions are determined as follows: rc (radius of the cross-section of the cylinder 22) = 9mm, r (distance between the inner arc of the metal branch 13 and the center of the spindle-shaped patch 11) = 7mm, W2 (width of the metal branch 13) = 1.4mm, and the distance from the outer arc of the metal branch 13 to the edge of the cylinder 22 is 0.6mm. W1 (width of the connecting rod 12) = 1mm, W (semi-minor axis of the spindle-shaped patch 11, i.e., half the total width of the narrowest part of the spindle-shaped patch 11) = 3.5mm, the length of the connecting rod 12 is 2.1mm, and the semi-major axis of the spindle-shaped patch 11, i.e., half the total width of the longest part of the spindle-shaped patch 11, is 4.9mm.

[0046] The metal branches 13 of the top metal patch 1 have an angular angle of 40°-150° (the angular angle is the central angle corresponding to the two edges of the metal branch 13, specifically 100° in embodiment 1), which provides continuous phase compensation for the reflective array, and the metal patch as a whole can be rotated to -45°, 0°, 45°, and 90°.

[0047] The dielectric layer 2 is made of F4B, with a relative permittivity of 2.65, a loss tangent of 0.001, and a thickness of [missing information]. h The width is 7.5 mm. The width of the gap I23 is 0.1-0.25 mm (0.2 mm in Example 1).

[0048] The bottom metal plate 3 is rectangular with a side length of 21mm, the circular plate 32 has a radius of 7mm, and the width of gap II 33 is the same as the width of gap I 23.

[0049] The rotating component 4 includes a rotating shaft with a diameter rb of 1.4-2 mm (1.4 mm in Example 1) and a length hb of 15 mm.

[0050] The rotating component 4 of the present invention also includes a power device such as a motor (e.g., a brushed / brushless DC micro motor, a micro planetary gearbox motor, or a piezoelectric / ultrasonic motor, etc.), which drives the rotating shaft to rotate by driving the power device, thereby driving the top metal patch 1, the cylinder 22 and the circular plate 32 to rotate as a whole.

[0051] This invention achieves the switching of the unit structure polarization conversion function by mechanically rotating the top metal patch 1 of the overall base unit. When the top metal patch 1 is mechanically rotated to 45° and -45° (adjustable within ±5°, i.e., 40°-50° and -40°-50° are both possible; when the angle of top metal patch A is 40°, the angle of top metal patch B is either 40° or -50°, meaning different top metal patches 1 have the same angle or are 90°, allowing for some error; the rotation angle of top metal patch 1 refers to the angle between the connecting rod 12 and the direction x, with a certain direction x (e.g., vertical direction) as 0°), the polarization conversion function is activated, defined as working mode 1, and the polarization conversion rate is as follows. Figure 5As shown, a polarization conversion efficiency of over 90% can be achieved within the 5.6-8.3 GHz range. When the overall mechanical rotation of the patch is 0° or 90° (adjustable within ±5°, i.e., -5°-5° and 85°-95°; when the angle of top metal patch A is 5°, the angle of top metal patch B 1 is either 5° or 95°, meaning different top metal patches 1 have the same angle or are at 90°, allowing for some error; the rotation angle of top metal patch 1 refers to the angle between the connecting rod 12 and the x-direction, with a certain direction x (e.g., vertical) as 0°), the polarization conversion function is turned off, defined as operating mode 2. In both operating modes, the unit reflection amplitude is within -2dB within the 5.6-8.7 GHz range, resulting in low loss. Simultaneously, continuous phase compensation can be achieved by continuously changing the extension angle of the surface metal extension line. When the entire system rotates by a single angle, phase coverage of over 180° can be achieved by changing the length of the extension line. According to the electromagnetic mirror principle, another angle under the same operating mode, together with this angle, can achieve phase coverage of over 360°. The phase shift curve is as follows: Figure 6 , Figure 7 As shown, it provides continuous phase compensation for the reflection array.

[0052] The rotation angle of the top metal patch 1 in different base units depends on the phase distribution. The specific calculation process of the actual target phase of each base unit is as follows: The mechanically reconfigurable reflector array system is laid out in a positive feed configuration. In order to convert the spherical wave radiated by the single-polarized feed source into a beam in the desired direction, each metasurface unit on the array surface must provide a specific compensation phase to cancel out the phase difference generated by the electromagnetic wave propagating in free space.

[0053] Establish a rectangular coordinate system, with the reflecting array located at... On the plane, the center of the array is the origin. The coordinates of the feed's phase center are set as (…). For the ( ) on the array surface There are ) metasurface units, whose physical center coordinates are ( ).

[0054] According to the electromagnetic wave propagation theory, the reference geometric distance from the feed phase center to the origin of the array surface is: , reaching the ( The geometric distance of the units is , respectively represented as:

[0055]

[0056] The direction of the antenna's main beam is defined in space as the elevation angle. and azimuth Then the ( The theoretical space relative phase difference required for each unit The calculation formula is:

[0057] in, For free space wavenumber, The operating wavelength corresponds to the center frequency.

[0058] The right side of the above equation consists of two physical mechanisms: the first term This is a spatial delay compensation term, used to accurately compensate for the phase delay caused by the path difference in the radiation from the feed to each unit.

[0059] Second item This is the linear phase gradient term. The physical essence of this term is based on phased array theory and the generalized Snell's law, by artificially introducing a phase gradient term that varies with the physical position coordinates within the two-dimensional plane of the array. The linearly varying phase accumulation forces a change in the normal direction of the isophase surface of the reflected wave, thereby enabling the beam to be positioned at a specified angle in space. The convergence and scanning of data.

[0060] The electromagnetic reflection phase of the metasurface unit has The periodic physical characteristics of the theoretical phase obtained from the above calculations require modeling. The phase is truncated and normalized to eliminate phase ambiguity. The normalized compensated phase... Represented as:

[0061] Metasurface units possess an inherent electromagnetic reflection reference phase under specific initial physical conditions. Finally assigned to the ( The true target phase of each unit for:

[0062] Based on this The two-dimensional spatial distribution is used to perform minimum error matching inversion on the continuous phase shift curve of the unit to complete the final array layout design.

[0063] like Figure 8 , Figure 9As shown, based on the phase compensation calculation results, the unit structures form a 29×29 reflective array. In operating mode 1, the array surface metal patches are rotated at angles of 45° and -45°, and the polarization conversion function is enabled, enabling linear polarization conversion. Mechanical rotation is performed on the metal patches of each unit structure in operating mode 1, rotating the patch with an overall rotation angle of -45° to 0° and the patch with an angle of 45° to 90°. At this point, each unit structure, after optimization of the surface metal patch size, can still provide the required compensation phase for the reflective array. The reflective array switches from operating mode 1 to operating mode 2, and the polarization conversion function of the reflective array is disabled. By mechanically rotating the surface metal patches of the unit structure, the polarization function of the reflective array is dynamically adjusted, thereby allowing for the measurement of brightness temperature data under different polarization states of the target.

[0064] like Figure 10 , Figure 11 The reflector array shown has a maximum gain of 29.7 dBi in both operating modes 1 and 2, and the 3 dB beamwidths in the E and H planes are both less than 4.3°, exhibiting narrow beam characteristics and low sidelobe levels, which can meet the high spatial resolution requirements of microwave radiometers.

[0065] Microwave radiometers detect sea surface temperature and wind fields at frequencies including 6.9 GHz. The mechanically reconfigurable polarization-tunable reflector array proposed in this invention achieves a polarization conversion rate of 95% at 6.9 GHz, and its operating mode can be switched by mechanically rotating the unit structure, achieving polarization tunability. This allows for flexible switching of polarization states and reception of target brightness and temperature data from different polarization states. It also features a narrow beam and low sidelobe level, meeting the requirements for high-resolution remote sensing of sea surface physical parameters. The mechanically reconfigurable polarization-tunable reflector array designed in this invention achieves dynamic adjustment of the linear polarization mode in the C-band, while possessing high polarization conversion rate and narrow beam characteristics. It also boasts advantages such as planar structure, low insertion loss, and easy system integration, providing a new approach for high-precision sea surface temperature detection with microwave radiometers and showing broad application prospects in the future field of marine microwave remote sensing.

[0066] Comparative Example 1 Based on Example 1, the structure of the central patch of the unit is modified, such as... Figure 12 As shown, the center of the unit is no longer a spindle-shaped patch, but is modified to two fan-shaped patches (made of metal). The radius of the fan-shaped patches is 3.5mm, the angle is 90°, and the two fan-shaped patches are symmetrical about the origin. Everything else is the same as in Example 1.

[0067] Figure 13The comparison of polarization conversion rates between Comparative Example 1 and Example 1 is shown. Original patch structure 1 corresponds to Example 1, while modified patch structure 2 corresponds to Comparative Example 1. As can be seen from the figure, the polarization conversion bandwidth of the unit structure after changing the shape of the central patch is significantly smaller in the C-band than the original structure. This indicates that the original structure is difficult to meet practical application requirements and has a low actual processing tolerance. Therefore, compared to the modified unit structure, the central patch design of the unit structure in this invention is preferred, as it can effectively broaden the polarization conversion bandwidth.

[0068] Comparative Example 2 Based on Example 1, the metal branches of the top metal patch are changed, such as... Figure 14 As shown, the metal branches of the unit structure are no longer arc-shaped, but arrow-shaped. The width of the arrow-shaped metal branch is 1.4 mm, the arrow angle is 90°, and the length of the arrow branch is 8 mm. Everything else is the same as in Example 1.

[0069] Figure 15 The diagram illustrates a comparison of polarization conversion between Example 1 and Comparative Example 2. Example 1 uses the original metal branch structure 1, while Comparative Example 2 uses a modified metal branch structure 2. As shown in the figure, the polarization conversion bandwidth of the unit structure after modifying the upper and lower metal branch structures is extremely narrow, and the polarization conversion rate at the target frequency is significantly lower than that of the original structure. Therefore, the top layer patch of this invention using the metal branch structure shown in Example 1 exhibits optimal performance, achieving a 95% polarization conversion rate at the target frequency, demonstrating broadband stability, and showing high tolerance for errors introduced during actual manufacturing.

[0070] Comparative Example 3 Based on Example 1, a 1-bit discrete phase compensation array is performed on the basic unit. A metal stub angle of 120° is selected as the discrete array unit structure. A 45° rotation of the metal patch is defined as state "0", and a -45° rotation is defined as state "1", with a 180° phase difference between the two. The "0" and "1" values ​​of the metasurface unit structure are used for 1-bit encoding arraying. Based on the phase compensation calculation results mentioned above, a proximity-based phase compensation strategy is adopted to achieve a discretized approximation of the ideal phase distribution. The required compensation amount within the range of -90° to 90° is replaced by state "0", and the required compensation amount within the range of 90° to 180° and -180° to -90° is replaced by state "1".

[0071]

[0072] Everything else is the same as in Example 1, and the array beam pattern is as follows: Figure 16 As shown.

[0073] Depend on Figure 16It can be seen that when a 1-bit discrete phase compensation array is used, the maximum gain of the reflection array decreases from 29.7 dBi to 25.6 dBi, while the sidelobe level increases significantly, and the beamwidth increases from 4.3° to 4.9°, resulting in obvious phase quantization errors. The results indicate that the continuous phase compensation array design of this invention is preferred, achieving high gain, narrow beam, and low sidelobe level characteristics, thereby meeting the high spatial resolution and high measurement accuracy requirements of microwave radiometers for detecting the physical parameters of sea surface targets.

[0074] Comparative Example 4 Based on Example 1, the metal branches of the top metal patch are changed, such as... Figure 17 As shown, the spindle-shaped patch 11 of the unit structure is no longer spindle-shaped, but square (with a side length of 7mm). The vertices of the square are connected to the connecting rods, and everything else is the same as in Embodiment 1.

[0075] Figure 18 The polarization conversion comparison between Example 1 and Comparative Example 4 is shown. Spindle-shaped patch structure 1 is Example 1, and square patch structure 2 is Comparative Example 4. The comparison shows that when the structure is changed to a square patch structure, the operating bandwidth of the unit structure is significantly reduced. At the same time, the polarization conversion rate decreases to a certain extent at the target frequency, resulting in a low actual processing tolerance. Furthermore, the original structure is less prone to performance fluctuations in the target frequency band, effectively broadening the polarization conversion bandwidth.

[0076] Comparative Example 5 Comparative Example 5, based on Example 1, modifies the metal branches of the top metal patch, such as... Figure 19 As shown, the spindle-shaped patch 11 of the unit structure is no longer a biaxially symmetrical spindle shape, but a uniaxially symmetrical eccentric spindle-shaped patch with a major axis of 10 mm and a minor axis of 6 mm. The position of the minor axis (the line connecting the widest points in the middle) is located at 1 / 3 of the major axis, and the opening angle of the metal branch 13 is set to 70°. Everything else is the same as in Example 1.

[0077] Figure 20 To compare the polarization conversion rates of the two structures at the same extension angle, based on Example 1, the angle of the metal branch 13 of the top metal patch 1 was changed to 70°, i.e. Figure 20The symmetrical spindle-shaped patch structure at both ends is Example 1 after changing the opening angle to 70°, while the asymmetrical spindle-shaped patch structure at both ends is Comparative Example 5. Simulation results show that when the central patch loses its geometric symmetry, the impedance characteristics of the structure on the orthogonal principal axes become mismatched within the range of 40°-80° metal branch extension angles. This leads to distortion of the surface current distribution and causes energy trapping at specific frequencies, resulting in the fragmentation of the polarization conversion band and a narrowing of the effective working bandwidth. In comparison, the symmetrical spindle-shaped patch used in this invention avoids the aforementioned trapping, ensuring efficient and continuous polarization conversion, making it the preferred design.

[0078] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0079] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A mechanically reconfigurable real-aperture microwave radiometer with tunable polarization metasurface reflective array, characterized in that, It includes multiple periodically arrayed basic units, which include a top metal patch (1), a dielectric layer (2), a bottom metal plate (3), and a rotating component (4) arranged in a stacked manner from top to bottom. The medium layer (2) includes a body (21) and a cylinder (22) fitted inside the body (21). A gap I (23) is provided between the body (21) and the cylinder (22). The top metal patch (1) is located on the cylinder (22). The bottom metal plate (3) includes a substrate (31) and a circular plate (32) located inside the substrate (31), and a gap II (33) is provided between the substrate (31) and the circular plate (32). The rotating component (4) is connected to the circular plate (32) to drive the top metal patch (1), cylinder (22) and circular plate (32) to rotate as a whole; The top metal patch (1) includes a spindle-shaped patch (11), a connecting rod (12) connected to the two long shaft ends of the spindle-shaped patch (11), and a metal branch (13) disposed at the end of the connecting rod (12), wherein the metal branch (13) is arc-shaped toward the spindle-shaped patch (11).

2. The metasurface reflection array as described in claim 1, characterized in that, The basic unit is a rectangle with a side length of 21mm.

3. The metasurface reflection array as described in claim 1, characterized in that, The length ratio of the major axis to the minor axis of the spindle-shaped patch (11) is 1.4-2.6:

1.

4. The metasurface reflective array as described in claim 3, characterized in that, The spindle-shaped patch (11) is symmetrical along both the long axis and the short axis.

5. The metasurface reflective array as described in claim 1, characterized in that, The length of the connecting rod (12) is 0.4-0.5 times the semi-major axis of the spindle-shaped patch (11).

6. The metasurface reflective array as described in claim 1, characterized in that, The metal branch (13) is symmetrically arranged with the connecting rod (12) as the center.

7. The metasurface reflective array as described in claim 1, characterized in that, The arc of the metal branch (13) is part of the arc centered on the center point of the spindle patch (11), and the central angle of the metal branch (13) is 40°-150°.

8. The metasurface reflective array as described in any one of claims 1-7, characterized in that, The widths of gap I (23) and gap II (33) are the same.

9. The metasurface reflective array as described in any one of claims 1-7, characterized in that, The rotating component (4) includes a rotating shaft with a diameter of 1.4-2 mm.

10. The metasurface reflective array according to any one of claims 1-7, characterized in that, The dielectric layer (2) is made of F4B, with a relative permittivity of 2.65, a loss tangent of 0.001, and a thickness of 7.5 mm.

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