A reconfigurable dual-polarization reflective surface antenna

Abstract

The present invention relates to a reconfigurable dual-polarized reflective surface antenna, which comprises m×n reflective surface units arranged in an array, each reflective surface unit comprising a dielectric substrate, a spiral cross dipole etched on the upper layer of the dielectric substrate, and a metal ground arranged on the lower layer of the dielectric substrate; the spiral cross dipole is used to receive electromagnetic waves and perform phase control on the electromagnetic waves, and finally reflect the electromagnetic waves; branches and PIN tubes are arranged on the spiral cross dipoles, and the miniaturization of the reflective unit is achieved by extending the current path through the branches, and the current path of the reflective surface unit is changed by controlling the cut-off or conduction state of the PIN tube, thereby changing the electrical length of the reflective surface unit to achieve a 180° reflection phase difference and realize beam reconstruction. The reflective surface unit proposed by the present invention adopts a central symmetrical structure, can realize dual-polarized beam reconfiguration, and realizes two-dimensional beam scanning, with a scanning range of up to ±60°.

Description

Technical Field

[0001] The invention relates to the field of communication technology, and in particular to a reconfigurable dual-polarization reflecting surface antenna. Background Art

[0002] With the rapid development of mobile communication technology, the communication environment is becoming more and more complex, and reconfigurable wireless communication has gradually become a key technology. In the millimeter wave frequency band, due to the high frequency and short wavelength, the diffraction ability of electromagnetic waves is poor, and the wireless channel is full of uncertainty and randomness, which seriously affects the communication quality between base stations and users. Therefore, intelligent communication systems based on reconfigurable reflective surfaces are becoming a research hotspot.

[0003] Reflective surface, or reflective array, is a common passive device based on the principle of phase compensation to achieve high-gain directional radiation. Reflective surface is usually a two-dimensional planar array composed of hundreds or thousands of sub-wavelength units, and the electromagnetic properties of each unit, including its amplitude, phase, and polarization, are controllable. For traditional reflective surfaces used to achieve single-beam directional radiation, once indicators such as the radiation direction are determined, the structure of each unit is determined and cannot be adjusted. Therefore, the application scenarios of such reflective surfaces are very limited; and for communication systems such as mobile communications, satellite communications, and radars, traditional reflective surfaces used to achieve single-beam directional radiation are difficult to meet the needs of these communication systems. Therefore, how to design a reflective surface that can meet the needs of communication systems such as mobile communications, satellite communications, and radars is a problem that needs to be considered at this stage. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a reconfigurable dual-polarization reflecting surface antenna to solve the shortcomings of the traditional reflecting surface.

[0005] The objective of the present invention is achieved through the following technical solutions: a reconfigurable dual-polarized reflecting surface antenna, comprising m×n reflecting surface units arranged in an array, each reflecting surface unit comprising a dielectric substrate, a spiral cross dipole etched on the upper layer of the dielectric substrate, and a metal ground arranged on the lower layer of the dielectric substrate; the spiral cross dipole is used to receive electromagnetic waves and perform phase control on the electromagnetic waves, and finally reflect the electromagnetic waves; branches and PIN tubes are arranged on the spiral cross dipoles, and the miniaturization of the reflecting unit is achieved by extending the current path through the branches, and the current path of the reflecting surface unit is changed by controlling the cut-off or conduction state of the PIN tube, thereby changing the electrical length of the reflecting surface unit to achieve a reflection phase difference of 180° and realize beam reconstruction.

[0006] The spiral cross dipole comprises a cross-shaped conductor which is centrally symmetrical. Extended conductors are respectively arranged in four directions of the cross-shaped conductor, and the extending direction of the extended conductors is clockwise.

[0007] The four directions of the cross-shaped conductor are respectively provided with branches of the same size, and the four branches are centrally symmetrical; and a PIN tube is provided on each extension conductor.

[0008] Each reflection surface unit is electrically connected to the control circuit and the FPGA, and the reflection surface is coded and regulated by controlling the cutoff and conductor states of the PIN tube on the reflection surface unit; the PIN tube cutoff state 0 corresponds to 0° phase compensation, and the conductor state 1 corresponds to 180° phase compensation.

[0009] When the feed position is determined, the phase required to be compensated for each reflection surface unit corresponding to different beam pointing angles, that is, the optical path difference from the feed to each reflection surface unit, is calculated using the principle of geometric optics. If the phase required to be compensated for a certain reflection surface unit is calculated to be within the interval of [270°, 360°] and [0°, 90°], the PIN tube of the reflection surface unit is controlled to be in the cut-off state, that is, the 0 state; if the phase required to be compensated for a certain reflection surface unit is calculated to be within the interval of [90°, 270°], the PIN tube of the emission surface unit is in the on state, that is, the 1 state; by controlling the state of the PIN tube on each reflection surface unit, the beam can be reconfigured, that is, the radiation pattern can be reconfigured.

[0010] The dielectric substrate is a F4BME220 dielectric substrate with a relative dielectric constant ε r =2.2, loss tangent is 0.009.

[0011] The present invention has the following advantages: a reconfigurable dual-polarization reflecting surface antenna can be used to achieve signal blindness compensation in millimeter wave communication and enhance the quality of user received signals; the reconfigurable reflecting surface of the present invention can achieve continuous wide-angle scanning of beams, and compared with mechanical scanning that can only achieve discrete beam scanning, the beam scanning of the present invention is more flexible and controllable and can meet wider application requirements; the reflecting surface unit of the present invention adopts a dual-polarization structure, so it can achieve dual-polarization beam scanning, and is more widely used than the reflecting surface of a single-polarization working mode; the reflecting surface unit of the present invention adopts branches to reduce the unit size, which is beneficial to improving the aperture efficiency of the reflecting surface and improving the system performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of a communication system based on smart reflective surfaces.

[0013] Figure 2 It is a structural diagram of the reflective surface unit.

[0014] Figure 3 This is the current distribution diagram of the PIN tube in the cut-off state of the reflection surface unit.

[0015] Figure 4 It is the current distribution diagram of the reflective surface unit PIN tube in the on state.

[0016] Figure 5 is the phase response of the reflecting surface unit in two states with frequency.

[0017] Figure 6 is the response of the reflection coefficient of the reflecting surface unit in two states to frequency.

[0018] Figure 7 is a top view of the reconfigurable reflective surface.

[0019] Figure 8 It is a schematic diagram of beam scanning.

[0020] Fig. 9 is the normalized beam scanning pattern.

[0021] Fig.10 is the peak gain plot, with θ b = 0 degrees and 20 degrees as examples.

[0022] Fig.11 It is a schematic diagram of dual polarization working mode;

[0023] In the figure: 1-base station, 2-obstacle, 3-intelligent reflective surface, 4-first user, 5-second user, 6-spiral cross dipole, 61-cross conductor, 62-extended conductor, 7-branch, 8-PIN tube, 9-dielectric substrate, 10-metal ground. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application provided below in conjunction with the drawings is not intended to limit the scope of protection of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. The present invention is further described below in conjunction with the drawings.

[0025] The present invention can encode and control the reflective surface by introducing a control circuit and a field programmable gate array (FPGA) to realize an intelligent reflective surface. The reflective surface proposed in the present invention can be used as a part of a wireless transmission channel to realize channel controllability, thereby expanding the wireless coverage range, realizing signal blind spot filling and enhancement, and greatly improving system performance. For example, for an application scenario where there is an obstacle between a transmitting end and a receiving end, a virtual line-of-sight link can be established by placing the reflective surface of the present invention to realize blind spot filling, especially for high frequency bands such as millimeter waves. For another example, for millimeter wave communication, the intelligent reflective surface of the present invention can be deployed near an existing base station to realize enhanced mobile broadband (eMBB). In addition, the reflective surface of the present invention can realize interference elimination and encrypted communication. The beam is reconfigurable, and the continuous adjustability of the beam is realized by controlling the on and off states of the PIN tube on the reflective surface unit. The reflective surface unit proposed in the present invention adopts a central symmetric structure, which can realize dual-polarization beam reconfiguration. The present invention realizes two-dimensional beam scanning with a scanning range of up to ±60°.

[0026] like Figure 1 The figure shows an intelligent communication system based on a reconfigurable intelligent reflective surface. Since the diffraction ability of millimeter waves is worse than that of electromagnetic waves in the sub-6G frequency band, when there is an obstacle 2 between the base station 1 and the first user 4 and the second user 5, the quality of the received signal will be seriously affected. By placing an intelligent reflective surface at an appropriate position and regulating the numerical control module at the back end of the reflective surface, the channel can be reconfigured, the signal blind spot can be filled, and the quality of the user's received signal can be enhanced. By controlling the state of each unit of the reflective surface, the beam can be reconfigured for different users (in different directions).

[0027] like Figure 2 The figure shows the reflection surface unit proposed by the present invention. The upper layer of the unit is a spiral cross dipole 6 made of metal, which is used to receive electromagnetic waves and perform phase control on them, and finally reflect electromagnetic waves. The spiral cross dipole 6 includes a cross-shaped conductor 61 that is centrally symmetrical. Extended conductors 62 are respectively arranged in four directions of the cross-shaped conductor 61, and the extending direction of the extended conductor 62 is clockwise. Branches 7 of the same size are respectively arranged in four directions of the cross-shaped conductor 61, and the four branches 7 are centrally symmetrical; a PIN tube 8 is arranged on each extended conductor 62.

[0028] The branch 7 is used to extend the current path to achieve unit miniaturization. The PIN tube 8 is an ideal PIN tube, with 4 in each unit. Cut-off (0 state) or conduction (1 state) corresponds to two phase states (0 degrees and 180 degrees). The middle layer is the F4BME220 dielectric substrate 9, with a relative dielectric constant ε r =2.2, loss tangent is 0.009. The lower layer is metal ground 10.

[0029] like Figure 3 and Figure 4 As shown in the figure, the cross-dipole surface current distribution at 30GHz corresponding to the PIN tube cut-off and on states, that is, the 0 and 1 states corresponding to the reflection surface unit, can be seen that when the PIN tube 8 is cut off, only a small part of the current at the end of the dipole is coupled to the other end, so the electrical length of the reflection surface unit at this time is reduced relative to the PIN tube 8 on state, so the reflection phase is different. By placing the PIN tube 8 at a suitable position, placing the PIN tube at this position can make the reflection surface unit produce two reflection phases of 0 and 180 degrees at the designed center frequency; if it is not placed at this position, it cannot produce two reflection phases of 0 and 180 degrees at the designed center frequency, but our design requires two reflection phases of 0 and 180 degrees, that is, 1 bit phase difference. Figure 5 The figure shows the phase variation with frequency of the reflection surface unit of the present invention in the ANSYS HFSS simulation software. It can be seen that the phase difference of the PIN tube 8 is around 180 degrees when it is in two states, wherein the phase difference is exactly 180 degrees at 30 GHz, and the phase difference changes to 180±20 degrees within the frequency range of 29-32.5 GHz. Figure 6 The reflection loss of the reflecting surface unit is given. The reflection loss can be ignored and the incident electromagnetic wave is almost completely reflected.

[0030] Figure 7 The figure shows a top view of the reflective surface 11 proposed by the present invention. The reflective surface is composed of 400 reflective surface units in 20 rows and 20 columns. The four PIN tubes 8 of each reflective surface unit are initially in the 0 state, that is, cut off. In order to verify the reflective surface proposed by the present invention, a conical horn 12 is placed above the reflective surface in an offset feeding manner as a feed source, as shown in FIG. Figure 8 As shown. The center of the horn aperture is aligned with the center of the reflecting surface. This distance is the focal length. The ratio of the focal length to the surface side length (i.e., the focal diameter ratio) is equal to 1. The angle at which the horn deviates from the normal of the reflecting surface, i.e., the offset angle, is 20 degrees. At this time, the polarization is in the yz plane, and beam scanning can be achieved in the yz plane, i.e., the radiation pattern can be reconstructed. The beam pointing angle is ( θ b ), different reflective surface units (x i ,y j ) can be calculated by the following formula:

[0031]

[0032] in, For the unit (x i ,y j ) is the phase to be compensated, k0 is the propagation constant, F is the focal length, is the initial phase corresponding to the center of the reflecting surface. Set to 0 degrees.

[0033] Fig. 9 The yz plane beam reconfigurable pattern of the reflecting surface at a frequency of 30 GHz is given, and beam scanning from -60 degrees to +60 degrees is realized, that is, the pattern is reconfigurable. Since the state of the PIN tube 8 is adjustable, the scanning beam is continuously adjustable. Here, only the scanning schematic diagram of each interval of 10 degrees is given. Although the beam gain at the edge is somewhat reduced relative to the center beam, there is still a good waveform. In general, the reconfigurable performance of the pattern of the reflecting surface of the present invention has been verified. Fig.10 Given θ b The gain curves for 0 and 20 degrees are shown in Figure 2. It can be seen that the gain is basically higher than 20dBi in the millimeter wave frequency range of 27-33GHz. Fig.11 As shown, the reflecting surface of the present invention can adopt a dual-feed mode, and another feed horn 13 is placed along the x-axis, so that ±60 degree continuous beam scanning can be achieved in the xz plane. At this time, the antenna polarization is in the xz plane. Therefore, the reflecting surface proposed by the present invention supports a dual-polarization working mode and can achieve two-dimensional scanning.

[0034] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A reconfigurable dual-polarized reflective surface antenna, characterized in that: It comprises m×n reflection surface units arranged in an array, each reflection surface unit comprising a dielectric substrate (9), a spiral cross dipole (6) etched on the upper layer of the dielectric substrate (9), and a metal ground (10) arranged on the lower layer of the dielectric substrate (9); the spiral cross dipole (6) is used to receive electromagnetic waves and perform phase control on the electromagnetic waves, and finally reflect the electromagnetic waves; branches (7) and PIN tubes (8) are arranged on the spiral cross dipoles (6), the branch (7) is used to extend the current path to achieve miniaturization of the reflection unit, and the current path of the reflection surface unit is changed by controlling the cut-off or on state of the PIN tube (8), thereby changing the electrical length of the reflection surface unit to achieve a reflection phase difference of 180° and realize beam reconstruction; The spiral cross dipole (6) comprises a centrally symmetrical cross-shaped conductor (61), and extension conductors (62) are respectively arranged in four directions of the cross-shaped conductor (61), and the extension direction of the extension conductor (62) is clockwise; Branches (7) of the same size are respectively arranged in four directions of the cross-shaped conductor (61), and the four branches (7) are centrally symmetrical; and a PIN tube (8) is arranged on each extension conductor (62).

2. The reconfigurable dual-polarized reflective surface antenna according to claim 1, characterized in that: Each reflection surface unit is electrically connected to a control circuit and an FPGA, and the reflection surface is coded and regulated by controlling the cut-off and conductor states of a PIN tube (8) on the reflection surface unit; the cut-off state of the PIN tube (8) is 0, corresponding to 0° phase compensation, and the conductor state is 1, corresponding to 180° phase compensation.

3. The reconfigurable dual-polarized reflective surface antenna according to claim 2, characterized in that: When the position of the feed source is determined, the phase required to be compensated for each reflection surface unit corresponding to different beam pointing angles, that is, the optical path difference from the feed source to each reflection surface unit, is calculated using the principle of geometric optics. If the phase required to be compensated for a certain reflection surface unit is calculated to be within the interval of [270°, 360°] and [0°, 90°], the PIN tube (8) of the reflection surface unit is controlled to be in a cut-off state, that is, a 0 state; if the phase required to be compensated for a certain reflection surface unit is calculated to be within the interval of [90°, 270°], the PIN tube (8) of the reflection surface unit is in a conducting state, that is, a 1 state; by controlling the state of the PIN tube (8) on each reflection surface unit, the beam can be reconfigured, that is, the direction pattern can be reconfigured.

4. A reconfigurable dual-polarization reflective surface antenna according to any one of claims 1 to 3, characterized in that: The dielectric substrate (9) is a F4BME220 dielectric substrate with a relative dielectric constant ε r =2.2, and the loss tangent is 0.009.

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