An intelligent reflecting surface unit with wideband low loss and an intelligent reflecting surface

Abstract

The application discloses a kind of intelligent reflecting surface unit with wideband low loss and intelligent reflecting surface, including interval air layer arrangement first dielectric substrate and second dielectric substrate, the first dielectric substrate one side is provided radiation patch, the one side of the second dielectric substrate is provided metal ground plate, the other side of second dielectric substrate is provided direct current control line, the radiation patch includes multiple coplanar metal patches, each metal patch is slotted in vertical direction and is connected using varactor, by controlling the direct current voltage at both ends of multiple varactors, so that the phase shift of intelligent reflecting surface unit continuously changes.The application not only reduces the reflection loss of unit, improves the directivity coefficient bandwidth of intelligent reflecting surface antenna, and the radiation performance has good stability in frequency band.

Description

Technical Field

[0001] This invention relates to the field of antenna design, and in particular to a smart reflector unit and smart reflector with wide bandwidth and low loss. Background Technology

[0002] With the development of wireless communication technology, the operating frequency bands of wireless communication networks are gradually shifting towards higher frequencies. However, high-frequency electromagnetic waves have poor diffraction properties when encountering obstacles, making wireless signals easily blocked and reducing their coverage area. Smart reflective surface technology provides a feasible solution to this problem.

[0003] Smart reflectors are composed of numerous meticulously designed artificial electromagnetic units, offering advantages such as low profile, low cost, low power consumption, and ease of fabrication. In terms of antenna structure, smart reflectors belong to the microstrip structure category. Traditional microstrip reflector antennas, due to their inherent resonant characteristics, have a narrow operating bandwidth, typically less than 5%. Furthermore, because the radiation field of a smart reflector is mainly concentrated in the lossy dielectric region between the top patch and the ground plane, traditional smart reflector antennas suffer from significant reflection losses. These narrow bandwidth and high losses severely limit the development potential of smart reflectors in wireless communication systems.

[0004] The working principle of a smart reflector is similar to that of a large-scale phased array antenna, essentially utilizing the principle of beamforming. When a far-field wireless signal is incident on the smart reflector in the form of a plane wave, each element on the smart reflector receives electromagnetic energy of equal amplitude and in phase. Based on the target deflection angle of the reflected beam and beamforming theory, the theoretical phase shift value of each element on the smart reflector is calculated. By adjusting the operating state of the electronic control devices on each element, the resonant characteristics of each element are adjusted, achieving phase shift of the reflected beam. The operating state of the electronic control devices in the element is assigned according to the theoretically required phase shift value, and the reflected energy of all elements in the array is shaped into a reflected beam, reflected in the target direction. From the above process, it can be seen that the quality of the smart reflector elements plays a decisive role in the system performance of the smart reflector. The key performance indicators of the elements are mainly the element reflection phase shift range, the slope of the reflection phase curve, and the element reflection loss. Summary of the Invention

[0005] In order to overcome the shortcomings of traditional intelligent reflector designs in the prior art, such as narrow bandwidth and high loss, the purpose of this invention is to provide an intelligent reflector unit and intelligent reflector with wide bandwidth and low loss.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A smart reflective surface unit with wide bandwidth and low loss includes a first dielectric substrate and a second dielectric substrate separated by an air layer. A radiating patch is disposed on one side of the first dielectric substrate, a metal ground plane is disposed on one side of the second dielectric substrate, and a DC control circuit is disposed on the other side of the second dielectric substrate. The radiating patch includes multiple coplanar metal patches, each of which has a vertical slot and is connected by a varactor tube. By controlling the DC voltage across the multiple varactor tubes, the phase shift of the smart reflective surface unit changes continuously.

[0008] Furthermore, by adjusting the electrical length of each metal patch to make the resonant frequency of each metal patch the same, the phase shift range of the superimposed smart reflective surface unit is increased.

[0009] Furthermore, adjacent metal patches are connected by microstrip lines, which pass through metal vias to the metal ground plane and connect to the DC control circuitry.

[0010] Furthermore, the arrangement of the multiple coplanar metal patches includes axially symmetric, centrally symmetric, and asymmetrical distributions.

[0011] Furthermore, the shape of the metal patch includes dumbbell shape, open square ring, open circular ring, or strip shape.

[0012] Furthermore, multiple variable capacitance tubes are controlled by the same control circuit to reduce the control complexity of the intelligent reflective surface unit.

[0013] Furthermore, the axisymmetric structure specifically includes a radiating patch comprising a dumbbell-shaped patch and an open-ended resonant ring patch. The dumbbell-shaped patch is disposed within the open-ended resonant ring patch. Both the dumbbell-shaped patch and the open-ended resonant ring patch are vertically slotted and connected by a varactor tube. Microstrip lines are respectively provided at both ends of the varactor tube to connect to the patch.

[0014] Furthermore, the multiple metal patches of the varactor are equivalent to multiple parallel RLC circuits with adjustable capacitance connected in series. When the equivalent capacitance of the varactor is adjusted, the resonant frequency of the equivalent RLC circuit will change, which in turn will change the reflection phase of the intelligent reflective surface unit. By adjusting the strength of the resonant frequency, the phase curves of the multiple resonant circuits can be smoothly connected, increasing the reflection phase shift range of the unit.

[0015] A smart reflective surface includes M×N smart reflective surface units arranged in a periodic manner.

[0016] Furthermore, the spacing between adjacent smart reflective surface units is W, where W is 0.25λ to 0.5λ, and λ is the wavelength of the center frequency.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] (1) Each unit of the intelligent reflective surface of the present invention can achieve 360° full-phase accurate phase assignment. Compared with the digital intelligent reflective surface, the phase quantization loss of the designed intelligent reflective surface is 0°.

[0019] (2) Compared with traditional smart reflectors, the broadband smart reflector proposed in this invention has a frequency range of 4.6GHz-5.2GHz with a phase shift range greater than 360° for each unit, and a phase shift range of 461° for the center frequency unit, resulting in a larger operating bandwidth. Furthermore, within this operating bandwidth, the reflection loss of the unit is relatively small, with an average unit loss of approximately 2.1dB for the center frequency unit.

[0020] (3) The slope of the reflection phase curve of the unit in this invention is small, the phase shift control of the unit is more uniform, and the parallelism of the phase shift curve of the unit at different frequency points is high, which is beneficial to increasing the gain bandwidth of the array.

[0021] (4) The side length of the unit of the present invention is 0.4λ, the array beam scanning range is ±60°, and no grating lobes are generated during scanning. The 3dB bandwidth reaches 17.8%, the sidelobe suppression is good, and the radiation pattern has good stability within the 3dB frequency band. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the broadband intelligent reflective surface of the present invention.

[0023] Figure 2 This is a top view of the broadband intelligent reflective surface unit structure.

[0024] Figure 3 This is a side view of the broadband intelligent reflective surface unit structure.

[0025] Figure 4 The reflection phase response curve of the broadband intelligent reflective surface unit.

[0026] Figure 5 The curves show the relationship between the reflection phase of the broadband smart reflector unit and the magnitude of the reflection voltage applied by the varactor diode when the frequencies are 4.8 GHz, 5 GHz, and 5.2 GHz.

[0027] Figure 6 The curve shows the relationship between the reflection loss of the broadband smart reflector unit and the equivalent capacitance of the varactor tube at a frequency of 5 GHz.

[0028] Figure 7 The curves showing the relationship between the reflection amplitude and frequency of the broadband intelligent reflective surface unit are given when the equivalent capacitance of the variable capacitance tube in the unit is 0.44pF, and the air layer thickness between the dielectric plate and the metal floor is set to 0mm, 1.2mm and 2.4mm respectively.

[0029] Figure 8The curves showing the relationship between the reflection phase and frequency of the broadband intelligent reflective surface unit are given when the equivalent capacitance of the variable capacitance tube in the unit is 0.44pF, and the air layer thickness between the dielectric plate and the metal floor is set to 0mm, 1.2mm and 2.4mm respectively.

[0030] Figure 9 This is a schematic diagram of an intelligent reflective surface structure consisting of 256 units.

[0031] Figure 10 The directional frequency curve of the broadband intelligent reflector.

[0032] Figure 11 The radiation pattern of the broadband intelligent reflector at a frequency of 5 GHz.

[0033] Figure 12 The radiation pattern of the broadband smart reflector at a frequency of 4.6 GHz.

[0034] Figure 13 The radiation pattern of the broadband smart reflector at a frequency of 5.5 GHz.

[0035] Figure 14 The beam scanning pattern of the broadband smart reflector at a frequency of 5 GHz.

[0036] Figures 15(a) and 15(b) are schematic diagrams of the dual-resonant strip symmetrical patch structure of Embodiment 3 of the present invention.

[0037] Figures 16(a) and 16(b) are schematic diagrams of the dual-resonant strip asymmetric patch structure of Embodiment 4 of the present invention.

[0038] Figure 17 This is a schematic diagram of the symmetrical dual-resonant patch structure of Embodiment 5 of the present invention;

[0039] Figure 18 This is a schematic diagram of the asymmetric three-resonant patch structure of Embodiment 6 of the present invention;

[0040] Figures 19(a) and 19(b) are schematic diagrams of the symmetrical three-resonant patch structure of Embodiment 7 of the present invention. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0042] Example 1

[0043] The one side and the other side mentioned in this embodiment 1 are opposite sides of the same dielectric substrate, specifically the upper surface and the lower surface.

[0044] like Figure 2 and Figure 3As shown, a smart reflective surface unit with wide bandwidth and low loss solves the technical problems of large reflection loss, low aperture efficiency, narrow operating bandwidth, and reflection phase not meeting 360-degree full-range modulation in the prior art. It includes a first dielectric substrate 2 and a second dielectric substrate 5 separated by an air layer 3. A radiating patch 1 is disposed on the upper surface of the first dielectric substrate 2, a metal ground plane 4 is disposed on the upper surface of the second dielectric substrate 5, and a DC control circuit 11 is disposed on the lower surface of the second dielectric substrate. The radiating patch includes multiple coplanar metal patches, each metal patch having a vertical slot and connected by a varactor tube. By controlling the DC voltage across the multiple varactor tubes, the phase shift of the smart reflective surface unit changes continuously. Adjacent metal patches are connected by microstrip lines, which pass through the metal ground plane via metal vias and are connected to the DC control circuit.

[0045] Furthermore, the metal patch is slotted in the vertical direction, which means that the metal patch is completely divided in the vertical direction.

[0046] Preferably, the first dielectric substrate 2 is an F4B substrate and the second dielectric substrate 5 is an FR4 substrate, both of which have a square structure and the side length of the unit is 24mm, which is 0.4 times the free space wavelength at the center frequency.

[0047] Preferably, the thickness of the first dielectric substrate 2 is 1.524 mm, the thickness of the air layer 3 is 1.2 mm, and the thickness of the second dielectric substrate 5 is 1.524 mm. The equivalent capacitance of the varactor diode varies from 0.24 pF to 0.64 pF.

[0048] Furthermore, the multiple coplanar metal patches in the radiating patch have their resonant frequencies made the same or similar by adjusting the electrical length of each metal patch. Due to the coupling between the multiple patches, the reflection phase shift curves generated by each patch are connected, and the total phase shift of the unit exceeds 360°.

[0049] Multiple coplanar metal patches can be distributed symmetrically along an axis, centrally symmetrically, or asymmetrically. The metal patches can have the same shape or different shapes, including dumbbell shape, open square ring, circular ring, or strip shape.

[0050] To reduce control complexity, the varactor tubes on multiple metal patches are controlled by the same DC control circuit.

[0051] In this embodiment, the radiating patch includes two coplanar metal patches, specifically adopting a dual-resonant axisymmetric radiating patch structure. The radiating patch includes a dumbbell-shaped patch 6 and an open resonant ring patch 7. The dumbbell-shaped patch is disposed inside the open resonant ring patch. In order to achieve the same or similar resonant frequencies for the two patches, the open resonant ring patch has openings at the top and bottom.

[0052] To ensure continuous phase shift of the intelligent reflective surface unit, slots are cut in the middle of the left and right sides of the open resonant ring patch, and a varactor tube is installed to connect the two parts; a slot is cut in the middle of the dumbbell-shaped metal patch, and a varactor tube is installed to connect the upper and lower parts, and the three varactor tubes are controlled by the same DC control line.

[0053] The dumbbell-shaped patch 6 and the open-loop resonant patch 7 are connected by two microstrip lines 9 with a width of 0.2 mm. The two microstrip lines 9 are connected to the metal ground plane 4 and the DC control circuit 11 via metal vias 10, respectively. The metal ground plane 4 is etched on the upper surface of the second dielectric substrate 5, and the DC control circuit 11 is etched on the lower surface of the second dielectric substrate 5.

[0054] Furthermore, the DC control line 11 is located below the metal floor to shield the DC control line from interference with the radio frequency signal and improve the unit's reflection performance.

[0055] In this embodiment, it is preferable to use a microstrip line with a width of 0.2 mm, which greatly reduces the interference of the microstrip line's radiation on the normal radiation of the metal patch.

[0056] The radiation intensity of a microstrip line in the microwave band is related to its width, while its DC performance only requires connection and is less affected by the microstrip line width. Therefore, the width of the microstrip line can be set to the narrowest linewidth within the processing accuracy range to simultaneously ensure DC connection and minimize radiated interference.

[0057] Alternatively, an inductor can be connected between the microstrip line and the metal patch to suppress interference radiation from the microstrip line. An inductor is a commonly used electronic device; its impedance characteristics are characterized by very low impedance in DC or low-frequency signals and very high impedance in high-frequency signals. Inductors can effectively suppress high-frequency radiation on microstrip lines without affecting the DC connectivity characteristics of the microstrip line.

[0058] Furthermore, an air layer is placed between the two dielectric substrates to reduce the electric field strength in the lossy dielectric region, thereby reducing the unit radiation loss. Specifically:

[0059] This invention introduces an air layer between the first dielectric substrate and the metal ground plane, reducing the equivalent dielectric constant of the hybrid dielectric plate between the upper surface radiating patch and the metal ground plane. This results in a longer wavelength of electromagnetic waves in the hybrid dielectric, while the physical dimensions of the smart reflective surface unit remain unchanged, leading to a reduction in its equivalent electrical length and enhanced mutual coupling between units. The increased electric field strength between array units alters the radiation field distribution of the units, weakening the electric field strength in the lossy dielectric region and thus reducing the unit's reflection loss. This also reduces the maximum reflection slope of the units, resulting in a smoother reflection phase curve, reduced reflection return loss, and a wider operating bandwidth.

[0060] In addition, adding an air layer weakens the electric field strength between the top radiating patch and the ground plane, and weakens the coupling strength between the multi-resonant structures. This reduces the interference on the reflection characteristics of the other resonant structure when adjusting the physical parameters of one resonant structure, which is beneficial for the optimized design of the multi-resonant unit radiating patch size.

[0061] The specific principle is as follows:

[0062] When an air layer is added, the equivalent circuit of the smart reflective surface unit changes (the equivalent circuit of the varactor remains unchanged), which increases the linearity of the phase shift curve of the unit.

[0063] The equivalent circuit of the intelligent reflective surface unit can be represented as a transmission line, and the top layer patch of the unit can be represented as a series RLC (R p ,L p C p The circuit has an impedance of Z. p Based on the measurement parameters in the varactor datasheet, the equivalent circuit of the varactor can be solved. For ease of calculation, the varactor is equivalent to a series RLC (R d ,L d C d The circuit has an impedance of Z. d .

[0064] After adding an air layer, the dielectric impedance Z s It becomes:

[0065]

[0066] The input impedance Z of the unit in The dielectric resistance Zs and the varactor tube resistance Z d , element impedance Z p The sum of parallel:

[0067] Z in =(Z d +Z p )||Z s (2)

[0068] The reflection coefficient of a unit is Γ, and the phase angle of Γ is the reflection angle of the unit.

[0069]

[0070] The circuit model extracted from the air-layer unit was simulated using the circuit simulation software ADS, and compared with the simulation results of the electromagnetic simulation software HFSS. The extracted circuit model is very close to the calculation results of the electromagnetic simulation software HFSS, indicating the accuracy of the model. As the air layer thickness h2 increases, the linearity of the reflection phase curve of the unit increases.

[0071] The working principle of this invention after loading the variable capacitance tube:

[0072] A single-resonant intelligent reflective surface unit with a varactor diode can be equivalent to a parallel RLC circuit with adjustable capacitance. Adjusting the equivalent capacitance of the varactor diode changes the resonant frequency of the equivalent RLC circuit, thus altering the reflection phase of the unit. The reflection phase curve of the single-resonant unit exhibits an "S"-shaped curve with capacitance variation, with a phase shift range of less than 360° and a relatively large slope near the resonant frequency, resulting in a narrow operating bandwidth. Multi-resonant unit designs couple multiple resonant structures with similar resonant frequencies onto a single unit. A multi-resonant unit with a varactor diode can be equivalent to multiple parallel RLC circuits with adjustable capacitance coupled in series. By optimizing the physical parameters of the multi-resonant structures on the unit, adjusting their resonant frequencies and strengths, the phase curves of the multi-resonant circuits are smoothly connected, thereby increasing the reflection phase shift range of the unit.

[0073] The radiation field is mainly concentrated in the lossy dielectric region between the radiating patch and the metal ground plane. The incident electromagnetic wave suffers significant loss in the lossy dielectric region, resulting in a high resonant intensity of the element. At this point, the Q value of the equivalent circuit of the reflecting element is large, and the reflection characteristics of the element are: a steep reflection phase curve, high reflection return loss, and a narrow operating bandwidth.

[0074] like Figure 4 As shown, the designed broadband intelligent reflector unit has broadband characteristics, with an operating frequency band of 4.6GHz-5.2GHz and a relative bandwidth of 12.24%. Within the operating frequency band, the unit's reflection phase shift range is greater than 360 degrees, and the slope of the unit's reflection phase curve is relatively small.

[0075] like Figure 5 As shown, at 4.8GHz, 5GHz, and 5.2GHz, the linearity of the reflection phase of the designed broadband smart reflector unit with the reverse voltage applied by the capacitor tube is high, and the phase shift range of the unit is greater than 360°, with the reflection phase shift range of the unit reaching 481° at the center frequency.

[0076] like Figure 6 As shown, at a frequency of 5GHz, the reflection amplitude loss of the unit is less than 3dB when the equivalent capacitance of the capacitor changes, with an average reflection loss of 2.1dB. Compared with traditional intelligent reflector unit designs, the intelligent reflector unit designed in this paper has lower reflection loss.

[0077] like Figure 7As shown, when the equivalent capacitance of the varactor in the unit is 0.44 pF, and the air layer thickness in the unit is 0 mm, the reflection loss near the resonant frequency is relatively large, and the distance between the two resonant frequencies is relatively large. When an air layer of 1.2 mm is introduced, the reflection loss near the resonant frequency of the unit is significantly reduced, and the distance between the two resonant frequencies is reduced. However, when the air layer thickness is 2.4 mm, the reflection loss of the unit is further reduced, but the two resonants merge into one resonant.

[0078] like Figure 8 As shown, when the equivalent capacitance of the varactor in the cell is 0.44 pF, and the air layer thickness in the cell is 0 mm, the reflection phase curve of the cell is steep near the two resonant frequencies, and the smoothness at the junction of the "S" curves generated by the two resonants is low, resulting in a large variation in the slope of the overall phase curve. When an air layer of 1.2 mm is introduced, the slope of the reflection phase curve of the cell is smaller near the resonant frequency, and the phase curve smoothness is higher, with a more constant overall phase curve slope. However, when the air layer thickness is 2.4 mm, the phase shift range of the cell decreases, and the phase curve smoothness is lower.

[0079] Example 2

[0080] like Figure 1 As shown, a smart reflective surface is composed of M×N smart reflective surface units arranged periodically as described in Example 1, where M and N are both > 1 and are positive integers. The spacing between adjacent smart reflective surface units is W, where W is 0.4λ to 0.5λ, and λ is the wavelength. Figure 1 It consists of 3x3 intelligent reflective surface units.

[0081] In this embodiment 2, the intelligent reflective surface is composed of 16 x 16 intelligent reflective surface units, specifically as follows: Figure 9 As shown.

[0082] To verify the performance of the designed intelligent reflector, an intelligent reflector consisting of M×N units was built in electromagnetic simulation software. Plane wave excitation was used, and the phase distribution of the array on the reflector was calculated based on the target reflection angle. The required reflection phase of each unit was calculated by taking the remainder of 360°, so that the phase shift range of each unit was [0, 360°]. The required capacitance state value was calculated based on the required phase and reflection phase curve of each unit, and the varactor tubes in each unit were assigned values. The array beam scanning performance and array broadband characteristics of the array were then observed.

[0083] like Figure 9 As shown, to verify the broadband and radiation characteristics of the smart reflector, a smart reflector array model consisting of 256 broadband elements was established in the simulation software, i.e., M=N=16.

[0084] like Figure 10It is the directivity frequency curve of the broadband intelligent reflecting surface. The maximum directivity coefficient of the broadband intelligent reflecting surface is 22.86 dBi at the center frequency point of 5 GHz. The 1 dB directivity coefficient bandwidth is 4.6 GHz - 5.5 GHz, and the relative bandwidth is 17.8%, showing good broadband characteristics.

[0085] Figures 11-13 It is the radiation pattern of the broadband intelligent reflecting surface when the frequencies are 5 GHz, 4.6 GHz, and 5.5 GHz. These three frequency points are respectively the boundaries and the center frequency point of the 1 dB bandwidth. The radiation pattern shape remains good, indicating that the intelligent reflecting surface still has good radiation performance within the directivity coefficient bandwidth.

[0086] As Figure 14 shown, when the frequency of the broadband intelligent reflecting surface is 5 GHz, the beam scanning range can reach ±60°. And within the scanning range, the sidelobe suppression is good, and no grating lobes appear. The designed intelligent reflecting surface has strong beam scanning ability.

[0087] Embodiment 3

[0088] The difference between this embodiment and Embodiment 1 lies in the different structures of the radiation patches.

[0089] The radiation patch in this embodiment adopts a dual-resonant strip symmetric patch structure, as shown in Fig. 15(a) and Fig. 15(b). The dual-resonant structure is composed of a strip patch at the center of the unit and a pair of strip patches symmetric about the left and right. Slots are cut in the middle positions of the three strip patches to separate them, and varactor 8 is used for connection. The upper and lower parts after separation are connected to the upper and lower parts of the adjacent strip patches through microstrip line 9. The resonant frequency of the strip patch is related to the length of the patch. According to the resonant frequencies of the center patch and the left and right symmetric patch pairs, the unit can be divided into two types: "low-high-low" and "high-low-high". As shown in Fig. 15(a), for the "low-high-low" type unit, the resonant frequencies of the upper metal patches are f1, f2, f1, the lengths of the left and right symmetric patch pairs are equal, and the resonant frequency is f1; the length of the middle patch is smaller than that of the left and right symmetric patch pairs, and the resonant frequency is f2. Since the patch resonant frequency is negatively correlated with the patch length, the size relationship of the resonant frequencies of the two resonant structures is: f1 < f2, so it is called the "low-high-low" unit. Correspondingly, when the lengths of the left and right patch pairs are less than the center patch, the resonant frequencies of the left and right patch pairs are greater than the resonant frequency of the center patch, and at this time the unit is a "high-low-high" unit. Both of these two types of units are dual-resonant units, but for symmetric placement, a center patch and left and right patch pairs are placed on the unit.

[0090] Three strip-shaped metal patches have a central slot, each housing a varactor diode. These varactor diodes are used to adjust the patch's resonant frequency. To reduce the number of control lines in the cell, two microstrip lines connect the upper and lower parts of the three strip patches, respectively. Due to the limited surface space of the cell, the mutual coupling between patches is significant when they are close together. Therefore, when adjusting the patch positions, the effect of patch spacing on the cell's reflection phase and amplitude must be considered.

[0091] Example 4

[0092] The difference between this embodiment and Embodiment 1 lies in the structure of the radiation patch.

[0093] In this embodiment, the radiating patch adopts a dual-resonant strip asymmetric patch structure, such as... Figure 16(a) and 16(b) As shown, there are two types: high-low and low-high. They are mainly composed of two asymmetrically distributed strip patches. A slot is cut in the middle of the two strip patches, which are connected by a varactor 8. The upper and lower parts after separation are connected by a microstrip line 9. The two strip patches have different lengths; the longer and shorter strip patches correspond to the low-frequency resonant frequency f1 and the high-frequency resonant frequency f2, respectively. As described in Embodiment 1, the asymmetrical dual-resonant patch unit can be divided into two types: "high-low" and "low-high." Here, "high" and "low" refer to the high and low resonant frequencies of each patch, respectively. The arrangement of the microstrip line and varactor is similar to that in Embodiment 1.

[0094] Example 5

[0095] The difference between this embodiment and Embodiment 1 lies in the structure of the radiation patch.

[0096] In this embodiment, the radiating patch is a symmetrical dual-resonant patch structure, specifically an outer circle with an inner strip patch.

[0097] like Figure 17 As shown, the dual-resonant structure consists of symmetrically distributed circular rings and strip patches. The length of the complete circular ring is much longer than the length of the strip patches inside it, therefore the resonant frequency of the complete circular ring is much lower than the frequency of the strip structure inside it. The top and bottom ends of the circular rings are cut off, and the left and right parts are slotted and connected by varactor diodes. The top and bottom parts of the strip patches are connected to the adjacent circular rings by microstrip lines. The resonant frequencies of the two resonant structures differ significantly and do not meet the phase accumulation condition of the dual-resonant unit. Therefore, the top and bottom parts of the circular rings are cut off, so that the resonant frequency of the open circular ring is close to the resonant frequency of the inner strip patch. The open circular ring and the strip patch correspond to the low-frequency and high-frequency resonant structures, respectively. Due to the large spacing between the open ring and the strip patch inside the ring, the coupling between the open ring and the inner patch is small, which facilitates the adjustment of the resonant frequency of the resonant structure while having little impact on the resonant frequency of the other structure.

[0098] Example 6

[0099] The difference between this embodiment and Embodiment 1 lies in the structure of the radiation patch.

[0100] This embodiment employs an asymmetric three-resonant patch structure, with low, medium, and high modes, such as... Figure 18 As shown.

[0101] The asymmetric three-resonant strip patch unit consists of three strip patches of varying lengths, asymmetrically distributed on the left, middle, and right. The three strip patches are connected by a varactor diode (8) through a central slot, and adjacent sections are connected by microstrip lines. The long, middle, and short strip patches correspond to the low-frequency, mid-frequency, and high-frequency resonant frequencies, respectively. The asymmetric three-resonant strip patch unit can be categorized as a "low-mid-high" three-resonant unit, where "low," "mid," and "high" refer to the high and low resonant frequencies of each patch, respectively. The arrangement of the microstrip lines and varactor diodes is similar to that in Embodiment 1.

[0102] Example 7

[0103] The difference between this embodiment and Embodiment 1 lies in the structure of the radiation patch.

[0104] This embodiment adopts a symmetrical three-resonant patch structure, as shown in Figures 19(a) and 19(b).

[0105] The symmetrical three-resonant "low-medium-high" symmetrical three-resonant patch cell consists of two outer rings symmetrically distributed on the left and right, and an inner strip patch. The middle part of the strip patch and the two outer rings are all slotted and separated, connected by a varactor tube 8, and adjacent parts are connected by a microstrip line 9.

[0106] The length of the complete ring is much longer than the length of the strip patch inside it, therefore the resonant frequency of the complete ring is much lower than the frequency of the internal strip structure. The resonant frequencies of the three-resonant structure differ significantly, failing to meet the phase accumulation condition of the three-resonant unit. Therefore, the upper and lower portions of the ring patch are truncated, making the resonant frequency of the open ring close to the resonant frequency of the internal strip patch.

[0107] This invention proposes a design method to enhance the operating bandwidth of a unit by utilizing the principle of multi-resonant structure coupling. The phase shift curve of the coupled multi-resonant structure results in a total phase shift range greater than 360°. The multi-resonant design increases the degree of freedom in unit design and improves the linearity of the unit's phase shift curve. To reduce the loss of the intelligent reflector unit, this invention proposes a design method that adds an air layer to the traditional intelligent reflector to reduce the electric field intensity in the lossy dielectric region, thereby reducing the unit's radiation loss.

[0108] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An intelligent reflecting surface unit with wideband low loss, characterized in that, The first dielectric substrate and the second dielectric substrate are provided with an air layer, the first dielectric substrate is provided with a radiation patch on one side, the second dielectric substrate is provided with a metal ground plate on one side, and the second dielectric substrate is provided with a direct current control line on the other side, the radiation patch comprises a plurality of coplanar metal patches, each metal patch is slotted in the vertical direction and connected by a varactor, by controlling the direct current voltage at both ends of the plurality of varactors, the phase shift of the smart reflectarray unit continuously changes; The arrangement of the plurality of coplanar metal patches comprises axial symmetry; The axial symmetry specifically is that the radiation patch comprises a dumbbell-shaped patch and an open resonant ring patch, the dumbbell-shaped patch is arranged in the open resonant ring patch, and the dumbbell-shaped patch and the open resonant ring patch are both slotted in the vertical direction and connected by a varactor, and the two ends of the varactor are respectively provided with a microstrip line connected patch.

2. The intelligent reflecting surface unit of claim 1, wherein, By adjusting the electrical length of each metal patch, the resonant frequencies of the metal patches are the same, and the phase shift range of the smart reflectarray unit is superimposed.

3. The intelligent reflecting surface unit of claim 1, wherein, The adjacent metal patches are connected by a microstrip line, and the microstrip line passes through the metal via hole to connect the metal ground plate and the direct current control line.

4. The smart reflective surface unit of any of claims 1-3, wherein, The shape of the metal patch comprises a dumbbell shape, an open square ring, an open circular ring or a strip shape.

5. The intelligent reflecting surface unit of claim 1, wherein, The plurality of varactors are controlled by the same control line to reduce the control complexity of the smart reflectarray unit.

6. The intelligent reflecting surface unit of claim 1, wherein, The plurality of metal patches loaded with varactors are equivalent to a plurality of parallel RLC circuits with adjustable capacitances which are coupled together in series, when the equivalent capacitance state of the varactor is adjusted, the resonant frequency of the equivalent RLC circuit changes, and then the reflection phase of the smart reflectarray unit changes, by adjusting the strength of the resonant frequency, the phase curve of the multi-resonant loop is smoothly connected, and the reflection phase shift range of the unit is increased.

7. A smart surface, characterized in that The smart reflectarray unit comprises M×N units arranged in a periodic manner.

8. The smart reflector of claim 7, wherein, The distance between adjacent smart reflectarray units is W, and W is 0.25λ~0.5λ, wherein λ is the wavelength.

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