Transparent folding reflective array antenna and beam transmission method

Abstract

The invention discloses a transparent folding reflective array antenna and a beam transmission method. The transparent folding reflective array antenna comprises a polarization selection layer and a polarization conversion phase modulation layer which are sequentially arranged from top to bottom, wherein the polarization selection layer is used for reflecting a linear polarization wave and transmitting a cross polarization wave vertical to the polarization direction of the polarization selection layer; the polarization conversion phase modulation layer is used for converting a linear polarization wave into a cross polarization wave vertical to the polarization direction of the polarization conversion phase modulation layer and performing phase regulation and control at the same time; and the feed source is arranged at the center of the polarization conversion phase modulation layer. The wave beam transmission method comprises the following steps: after the feed source emits a y polarized wave, the y polarized wave is reflected by the polarization selection layer to the polarization conversion phase modulation layer and is converted into an x polarized wave at the polarization conversion phase modulation layer, phase regulation is carried out to enable the wave beam to point to a designed direction, and then the wave beam is transmitted through the polarization selection layer. According to the method, the requirements of communication, radar detection and the like can be met while the naked eye observability is ensured.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of antennas, and particularly relates to a transparent folded reflectarray antenna and a beam transmission method. BACKGROUND

[0002] The folded reflectarray antenna is generally composed of a polarization selection layer, a polarization conversion and phase modulation layer, and a feed source. Since the waves emitted by the feed source are reflected inside the folded reflectarray antenna, the profile of the folded reflectarray antenna can be reduced to 1 / 2 of that of a traditional planar reflectarray, which is conducive to the realization of antenna miniaturization. The characteristics of high gain and miniaturization of the folded reflectarray antenna have great development potential in improving the quality of satellite communication and improving the detection accuracy of radar.

[0003] With the increasing complexity of current wireless communication systems and the continuous compression of installation space for various devices, in order to improve the space utilization, the places that originally need to be transparently observed also need to be fully utilized. At present, the existing folded reflectarray antennas cannot be installed in scenarios that need to be transparent, for example, the patent application with the publication number "CN116845579A" proposes "a folded reflectarray antenna based on double metasurfaces", which adopts a folded reflectarray antenna design based on double metasurfaces. By setting a transmissive metasurface on the other side of the polarization grating array, an additional design freedom is provided, and the transmissive phase of the transmissive metasurface unit is optimized to realize secondary adjustment of the electromagnetic wave phase and expand the gain bandwidth of the array. Since the antenna design uses a large area of metal patches, it must result in a very low transmittance of the antenna, which cannot be installed in scenarios that require optical transparency, such as observation windows of vehicles, ships, and aircraft, glasses of buildings, various electronic display screens, and solar panels that require sunlight. SUMMARY

[0004] The purpose of the present application is to solve the problems in the prior art, and to provide a transparent folded reflectarray antenna and a beam transmission method, which realizes the transparency of the folded reflectarray and meets the needs of communication, radar detection, and other requirements while ensuring the observability of the naked eye.

[0005] In order to achieve the above purpose, the present application has the following technical solutions: In a first aspect, a transparent folded reflectarray antenna is provided, which includes a polarization selection layer and a polarization conversion and phase modulation layer arranged in order from top to bottom. The polarization selection layer is used to reflect a linearly polarized wave and transmit a cross-polarized wave perpendicular to the polarization direction of the polarization selection layer. The polarization conversion and phase modulation layer is used to convert a linearly polarized wave into a cross-polarized wave perpendicular to the polarization direction of the polarization conversion and phase modulation layer, while the phase is controlled. The feed source is arranged at the center of the polarization conversion and phase modulation layer.

[0006] As a preferred embodiment, the polarization selective layer includes a first transparent dielectric body and a first metal line etched on the surface of the first transparent dielectric body, the first metal line being periodically arranged on the surface of the first transparent dielectric body.

[0007] As a preferred embodiment, the transmittance of the polarization selective layer is based on the transmittance of the first transparent medium body itself.

[0008] As a preferred embodiment, the polarization conversion phase modulation layer includes a second transparent dielectric body, the upper surface of which is a resonant double-ring structure made of a second metal wire, and the lower surface of which is a shielding film made of metal mesh.

[0009] As a preferred embodiment, the resonant double-ring structure consists of two concentric squares formed by two second metal wires, with equal gaps in the same direction; the center of the two concentric squares coincides with the center of the polarization conversion phase modulation layer.

[0010] As a preferred embodiment, the transmittance of the polarization conversion phase-tuning layer is based on the product of the transmittance of the second transparent medium body and the transmittance of the shielding film.

[0011] As a preferred option, the overall transmittance of the transparent folded reflective array antenna is the product of the transmittance of the polarization selection layer and the polarization conversion phase modulation layer.

[0012] As a preferred option, the feed source uses a standard gain horn antenna of 18GHz~40GHz.

[0013] Secondly, a beam transmission method based on the aforementioned transparent folded reflective array antenna is provided. After a y-polarized wave is emitted by the feed source, the y-polarized wave is reflected by the polarization selection layer to reach the polarization conversion phase modulation layer. In the polarization conversion phase modulation layer, it is converted into an x-polarized wave, and the phase is modulated to make the beam point in the designed direction. Subsequently, the beam is transmitted through the polarization selection layer.

[0014] As a preferred approach, the required phase at each polarization conversion unit in the polarization conversion phase modulation layer is calculated using the phase compensation formula to generate the corresponding array. The required phase at each polarization conversion unit is related to the focal diameter ratio, beam pointing, and feed position of the transparent folded reflective array antenna. After determining the beam pointing and focal diameter ratio, the optimal focal diameter ratio is determined by simulation optimization of different focal diameter ratios.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: This invention proposes a transparent folding reflective array antenna, achieving for the first time a transparent design for a folding reflective array. This innovative breakthrough enables the antenna to be widely used in observation windows of vehicles, ships, and aircraft. In these scenarios, the transparent antenna does not obstruct the line of sight, ensuring clear visibility for operators, while simultaneously enabling communication and radar detection functions, thus enhancing the information and intelligence level of the vehicle. In the construction field, it can be applied to glass surfaces, neither affecting the building's lighting nor its aesthetics, while also meeting internal communication needs. For various electronic displays, the transparent antenna does not obstruct the displayed content, ensuring display quality while enabling signal transmission and reception. Using this antenna on solar panels that require sunlight allows for communication functions without affecting the solar panels' ability to receive sunlight and generate electricity, greatly expanding the antenna's application range. This invention ensures high light transmittance while maintaining visual visibility, allowing light to pass smoothly through the antenna and meeting basic needs such as observation and lighting. Simultaneously, it also enables important functions such as communication and radar detection. In communications, it can efficiently receive and transmit signals, ensuring stable information transmission; in radar detection, it can accurately detect and locate targets. This design, which balances light transmittance and functionality, allows the antenna to adapt to various complex application environments, meeting diverse performance requirements in different scenarios. Compared to other transparent reflective array antennas, this invention effectively reduces the antenna's profile height while maintaining light transmittance. Through a rational structural design, the polarization selection layer, polarization conversion phase modulation layer, and feed source are optimized, reducing the antenna's vertical space footprint. This miniaturization not only reduces manufacturing costs and installation difficulty but also makes the antenna more portable and deployable. In space-constrained scenarios, such as small aircraft and portable electronic devices, miniaturized antennas can be better integrated into the equipment, improving overall performance and portability. The unique structural design of the antenna structure, with the polarization selection layer and polarization conversion phase modulation layer arranged sequentially from top to bottom, and the feed source positioned at the center of the polarization conversion phase modulation layer, provides strong assurance for the antenna's performance stability. The polarization selection layer can precisely reflect a linearly polarized wave while transmitting a cross-polarized wave perpendicular to its polarization direction, achieving effective separation and processing of waves with different polarizations. The polarization conversion phase modulation layer can convert a linearly polarized wave into a cross-polarized wave perpendicular to its own polarization direction and precisely control its phase, thereby optimizing the antenna's radiation characteristics and improving signal transmission quality and detection accuracy. Positioning the feed at the center of the polarization conversion phase modulation layer enables more uniform signal reception and transmission, reducing signal loss and interference, and improving the overall performance and stability of the antenna, demonstrating broad market application prospects and significant practical value. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the technical solutions of this application. The illustrative embodiments and descriptions of this application are only used to explain this application and do not constitute an improper limitation on the scope of protection of this application.

[0017] Figure 1 A schematic diagram of the overall structure of the transparent folding reflective array antenna according to an embodiment of the present invention; Figure 2 A schematic diagram illustrating the working principle of the transparent folding reflective array antenna according to an embodiment of the present invention; Figure 3(a) is a top view of the polarization selection layer in an embodiment of the present invention; Figure 3(b) is a side view of the polarization selection layer in an embodiment of the present invention. Figure 4 The reflection coefficient and transmission coefficient curves of the polarization selection layer in this embodiment of the invention; Figure 5(a) is a top view of the polarization conversion phase modulation layer in an embodiment of the present invention; Figure 5(b) is a side view of the polarization conversion phase modulation layer in an embodiment of the present invention; Figure 6(a) S21 curve of polarization conversion phase modulation layer in an embodiment of the present invention; Figure 6(b) Reflection phase curve of the polarization conversion phase modulation layer in an embodiment of the present invention; Figure 7 Gain curve of the feed antenna in an embodiment of the present invention; Figure 8(a) Phase distribution diagram of the array surface calculated by the phase compensation formula of the present invention; Figure 8(b) shows the array simulation model calculated by the phase compensation formula in the embodiment of the present invention; Figure 9(a) E-plane radiation pattern of the overall simulation center frequency of the transparent folding reflective array antenna of the present invention at 28 GHz; Figure 9(b) H-plane radiation pattern of the overall simulation center frequency of the transparent folding reflective array antenna of the present invention at 28 GHz; Figure 10 Gain curves at different frequencies of the overall simulation of the transparent folding reflective array antenna in this embodiment of the invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] In this invention, the serial numbers assigned to components, such as "first," "second," etc., are merely used to distinguish the described objects and do not have any sequential or technical meaning. Furthermore, the terms "connected" and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. In the description of this invention, it should be understood that the terms "upper," "lower," "center," "vertical," "intersecting," "periodic arrangement," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are merely for the convenience of describing the invention and simplifying the description, not to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0020] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0021] Please see Figure 1 This invention provides a transparent folding reflective array antenna with a center frequency of 28 GHz. It includes a polarization selection layer 101 and a polarization conversion phase modulation layer 102 arranged sequentially from top to bottom. The polarization selection layer 101 reflects a linearly polarized wave while transmitting a cross-polarized wave perpendicular to the polarization direction of the polarization selection layer 101. The polarization conversion phase modulation layer 102 converts a linearly polarized wave into a cross-polarized wave perpendicular to the polarization direction of the polarization conversion phase modulation layer 102, while simultaneously modulating the phase. It also includes a feed 103 disposed at the center of the polarization conversion phase modulation layer 102.

[0022] In one possible implementation, referring to Figures 3(a) and 3(b), the polarization selective layer 101 of this embodiment includes a first transparent dielectric body 1011 and first metal lines 1012 etched on the surface of the first transparent dielectric body 1011. The first metal lines 1012 are periodically arranged on the surface of the first transparent dielectric body 1011. The first metal lines 1012 are fine metal lines with a width of 30 μm, and are located below quartz glass (dielectric constant 3.75, loss tangent 0.004). Wherein, P = 4.5 mm, d = 0.67 mm, and h = 0.5 mm. By simulating and analyzing the S11 and S22 parameters of the polarization selective layer 101, the transmission and reflection performance of the polarization selective layer 101 can be analyzed. Figure 4 The reflection coefficient and transmission coefficient of the polarization selective layer in an embodiment of the present invention are shown, where S11 represents the amplitude of the y-polarized wave being reflected, and S21 represents the amplitude of the x-polarized wave being transmitted. Both are always greater than -1dB, indicating that the y-polarized wave is basically reflected, while the x-polarized wave is basically transmitted.

[0023] In microwave transmission and antenna design, the S11 and S22 parameters, as core components of scattering parameters (S-parameters), are used to describe the reflection characteristics of the input and output ports, respectively, and are key indicators for evaluating antenna performance.

[0024] The S11 (input reflection coefficient / input return loss) parameter represents the ratio of the reflected wave to the incident wave at the input port when the output port is matched. The S11 parameter reflects the degree of impedance matching at the antenna input port. The smaller the S11 parameter value, the less reflected energy, the better the impedance matching, and the lower the energy loss.

[0025] The S22 (output reflection coefficient / output return loss) parameter represents the ratio of the reflected wave to the incident wave at the output port when the input port is matched. The S22 parameter reflects the impedance matching degree of the antenna output port. The smaller the S22 parameter value, the less energy is reflected at the output port, and the higher the transmission efficiency.

[0026] In one possible implementation, referring to Figures 5(a) and 5(b), the polarization conversion phase modulation layer 102 of this embodiment includes a second transparent dielectric body 1022. The upper surface of the second transparent dielectric body 1022 is a resonant double-ring structure made of second metal wires 1021, and the lower surface of the second transparent dielectric body 1022 is a shielding film 1023 made of metal mesh with a sheet resistance of 0.06Ω. The resonant double-ring structure consists of two concentric squares formed by two second metal wires 1021, with equal-sized gaps along the same direction; the centers of the two concentric squares coincide with the center of the polarization conversion phase modulation layer 102. The polarization conversion phase modulation layer 102 of this embodiment is also designed with fine metal wires, which not only achieves polarization conversion but also has good phase modulation capability. The metal wires are etched on the upper surface of the transparent dielectric, and the lower surface of the transparent dielectric is a shielding film made of metal mesh, which has high light transmittance and low sheet resistance, providing excellent shielding effect. By simulating and analyzing the S21 and reflection phase of the polarization conversion phase modulation layer 102, the polarization conversion capability and phase modulation capability of the polarization conversion phase modulation layer 102 in this embodiment of the invention can be analyzed. In the figure, P=4.5mm, L1=2.2mm, L2=1.2mm, L3=L4=0.2mm, h=1.5mm. Referring to Figures 6(a) and 6(b), it can be seen that the reflection coefficient of the polarization conversion phase modulation layer 102 is always above -1.2dB, which indicates that most of the incident y-polarized wave is converted into x-polarized wave and reflected. The polarization conversion phase modulation layer 102 has good polarization conversion capability while having high light transmittance. At the same time, the polarization conversion phase modulation layer 102 can cover 180° of phase by changing the size, and 360° phase modulation can be achieved by mirror flipping the polarization conversion phase modulation layer 102. The full-coverage phase modulation makes the beam control of the antenna more precise and flexible.

[0027] In one possible implementation, please refer to Figure 7 To avoid processing complexity, the feed 103 in this embodiment of the invention uses a standard gain horn antenna of 18GHz~40GHz. The horn antenna has a gain of 15.3dBi at 28GHz, and the 3dB beamwidths of the E-plane and H-plane are 24.77° and 26.77°, respectively.

[0028] In one possible implementation, the upper and lower polarization selection layers 101 and the polarization conversion phase modulation layer 102 of the transparent folding reflective array antenna of this embodiment are both 135mm × 135mm in size, with 30 × 30 elements arranged accordingly. Eight × 8 elements are removed from the center of the polarization conversion phase modulation layer 102, and a 30mm × 35mm notch is provided for placing a horn. The beam points towards the center of the array at an angle of (0°, 0°), and the focal diameter ratio is ultimately determined to be 0.7. Figures 8(a) and 8(b) show the array phase distribution calculated according to the phase compensation formula and the corresponding simulation model.

[0029] The transparent folding reflective array antenna proposed in the embodiment of the present invention is simulated as a whole. Figure 9(a) and Figure 9(b) are the E-plane and H-plane radiation patterns of the center frequency of 28 GHz, respectively. It can be seen that the beam is effectively controlled and points to the center direction, and the sidelobe level is less than -14 dBi and the cross-polarization voltage is less than -25 dBi. Figure 10 The figure shows the gain curves of the transparent folding reflective array antenna at different frequency points in the overall simulation of the present invention. It can be seen that the peak gain of the reflective array is located at the center frequency, with a value of 27 dBi and a 3 dB bandwidth of approximately 28%.

[0030] Because the metal wires used in this invention are extremely fine and have an extremely low duty cycle, the transmittance of the polarization selection layer 101 in this embodiment is based on the transmittance of the first transparent medium body 1011 itself, specifically close to the transmittance of the quartz glass itself, approximately 93%. The transmittance of the polarization conversion phase modulation layer 102 is based on the product of the transmittance of the second transparent medium body 1022 and the transmittance of the shielding film 1023, specifically the product of the transmittance of the quartz glass and the transmittance of the underlying metal mesh shielding film, approximately 71%. The overall transmittance of the transparent folded reflective array antenna is the product of the transmittance of the polarization selection layer 101 and the transmittance of the polarization conversion phase modulation layer 102, approximately 66%. In actual products, the transmittance of the antenna can be further increased by using an anti-reflection coating.

[0031] Another embodiment of the present invention also proposes a beam transmission method for a transparent folded reflective array antenna, comprising: after emitting a y-polarized wave through a feed 103, the y-polarized wave is reflected by a polarization selection layer 101 to a polarization conversion phase modulation layer 102, where it is converted into an x-polarized wave and the phase is modulated to make the beam point in the designed direction, and then the beam is transmitted through the polarization selection layer 101.

[0032] In one possible implementation, when the feed 103 emits a TM-polarized wave, it is reflected by the upper polarization selection layer 101 and converted into a TE-polarized wave by the lower polarization conversion and phasing layer 102. The phase is then modulated to direct the beam in the designed direction before it is transmitted through the polarization selection layer 101. In the waveguide, the TE / TM mode describes the field distribution of the guided electromagnetic wave (e.g., the presence of longitudinal electric or magnetic field components), while the X / Y-polarized wave describes the transverse vibration direction of the electric field vector. TM-polarized waves (Transverse Magnetic Wave) have no magnetic field component in their propagation direction but have an electric field component; TE-polarized waves (Transverse Electric Wave) have no electric field component in their propagation direction but have a magnetic field component. Both TE and TM waves must have an operating frequency higher than the cutoff frequency to propagate in the waveguide; the cutoff frequency is determined by the waveguide dimensions and mode parameters.

[0033] In one possible implementation, the present invention calculates the required phase at each polarization conversion unit in the polarization conversion phase modulation layer 102 using a phase compensation formula to generate the corresponding array. The required phase at each polarization conversion unit is related to the focal diameter ratio, beam pointing, and position of the feed 103 of the transparent folded reflective array antenna. After determining the beam pointing and focal diameter ratio, the optimal focal diameter ratio is determined by simulation optimization of different focal diameter ratios.

[0034] Compared to current research, the transparent folding reflective array antenna of this invention achieves transparency of the folding reflective array for the first time. It is expected to be applied to observation windows of vehicles, ships, aircraft, etc., glass of buildings, various electronic displays, solar panels that require sunlight, etc., while ensuring visual observability and meeting the needs of communication, radar detection, etc.

[0035] Compared to other transparent reflective array antennas, the transparent folded reflective array antenna of this invention can effectively reduce the profile while ensuring light transmittance, thus achieving antenna miniaturization.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of protection involved.

[0037] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A transparent folded reflectarray, characterized in that, The transparent folded reflectarray antenna comprises a polarization selection layer (101) and a polarization conversion phase modulation layer (102) arranged in sequence from top to bottom; the polarization selection layer (101) is used for reflecting one linearly polarized wave and transmitting cross-polarized wave perpendicular to the polarization direction of the polarization selection layer (101); the polarization conversion phase modulation layer (102) is used for converting one linearly polarized wave into cross-polarized wave perpendicular to the polarization direction of the polarization conversion phase modulation layer (102) and simultaneously performing phase modulation; The transparent folded reflectarray antenna further comprises a feed source (103) arranged at the center of the polarization conversion phase modulation layer (102).

2. The transparent folded reflectarray antenna of claim 1, wherein, The polarization selection layer (101) comprises a first transparent medium body (1011) and a first metal wire (1012) etched on the surface of the first transparent medium body (1011), and the first metal wire (1012) is arranged periodically on the surface of the first transparent medium body (1011).

3. The transparent folded reflectarray antenna of claim 1, wherein, The light transmittance of the polarization selection layer (101) depends on the light transmittance of the first transparent medium body (1011).

4. The transparent folded reflectarray antenna of claim 1, wherein, The polarization conversion phase modulation layer (102) comprises a second transparent medium body (1022), and the upper surface of the second transparent medium body (1022) is a resonant double-loop structure made of a second metal wire (1021), and the lower surface of the second transparent medium body (1022) is a shielding film (1023) made of a metal wire mesh.

5. The transparent folded reflectarray antenna of claim 4, wherein, The resonant double-loop structure is composed of two concentric square frames formed by two second metal wires (1021), and the two concentric square frames have equal gaps in the same direction. The centers of the two concentric square frames coincide with the center of the polarization conversion phase modulation layer (102).

6. The transparent folded reflectarray antenna of claim 4, wherein, The light transmittance of the polarization conversion phase modulation layer (102) depends on the product of the light transmittance of the second transparent medium body (1022) and the light transmittance of the shielding film (1023).

7. The transparent folded reflectarray antenna of claim 1, wherein, The light transmittance of the transparent folded reflectarray antenna as a whole is the product of the light transmittances of the polarization selection layer (101) and the polarization conversion phase modulation layer (102).

8. The transparent folded reflectarray antenna of claim 1, wherein, The feed source (103) adopts a standard gain horn antenna with a frequency of 18GHz-40GHz.

9. A method of beam transmission based on the transparent folded reflectarray of any of claims 1 to 8, characterized in that, After the y-polarized wave is emitted by the feed source (103), the y-polarized wave is reflected by the polarization selection layer (101) to the polarization conversion phase modulation layer (102), is converted into an x-polarized wave in the polarization conversion phase modulation layer (102), and is subjected to phase modulation to make the beam point to the designed direction, and then the beam is transmitted through the polarization selection layer (101).

10. The method of claim 9, wherein, The phase required at each polarization conversion unit in the polarization conversion phase modulation layer (102) is calculated by a phase compensation formula to generate a corresponding array, and the phase required at each polarization conversion unit is related to the focal diameter ratio of the transparent folded reflectarray antenna, the beam pointing direction and the position of the feed source (103); after the beam pointing direction and the focal diameter ratio are determined, the optimal focal diameter ratio is determined by simulation optimization of different focal diameter ratios.

Images