A reconfigurable refractive metasurface antenna feed placement method

Abstract

This invention discloses a method for placing a feed source for a reconfigurable refractive metasurface antenna, applicable to communication between a base station and a user equipped with a reconfigurable refractive metasurface, including maintaining the feed source angle T. i‑1 Unchanged, based on the user's received signal-to-noise ratio γ i By defining the coverage, we obtain the optimal coverage S. i and the corresponding feed position Q i Maintain feed position Q i Unchanged, based on the user's received signal-to-noise ratio γ′ i By defining the coverage, we obtain the optimal coverage S′. i and the corresponding feed angle T i When the optimal coverage S′ i With optimal coverage S′ i+1 When the difference is less than a preset threshold, the optimal feed position Q is obtained. i With the optimal feed angle T i Use the optimal feed position Q i With the optimal feed angle T i The invention involves placing the feedhorn. By iteratively selecting the optimal feedhorn position and angle, the coverage area of ​​the base station can be maximized.

Description

Technical Field

[0001] This invention relates to the field of electronics, specifically to a method for placing a feed source for a reconfigurable refractive metasurface antenna. Background Technology

[0002] Massive MIMO is a crucial component of future wireless communication. Existing massive MIMO systems utilize traditional phased array antennas for beamforming. However, traditional phased arrays suffer from high power consumption and high cost. To address this issue, reconfigurable reflective metasurface antennas have recently been proposed. A reconfigurable reflective metasurface antenna consists of a feed and a reflective metasurface. The reflective metasurface is an array of multiple subwavelength elements. Each element has a PIN diode; by adjusting the bias voltage of this diode, the reflection phase shift of the element changes. The beamforming process of this antenna is as follows: the signal emitted by the feed is reflected after hitting each element. During this reflection, the metasurface element applies a certain phase shift to the signal. By adjusting the bias voltage on the diode, the reflection phase shift of the element is appropriately set, thus achieving beamforming. However, this antenna has the following drawback: because the feed can block the reflected wave to some extent, the antenna's radiation efficiency is not high. Summary of the Invention

[0003] To address the issue of low antenna radiation efficiency in existing reconfigurable reflective metasurface antennas due to feed obstruction, this invention proposes a feed placement method for reconfigurable refractive metasurface antennas. This method obtains the feed placement by considering the relationship between the feed position, angle, and optimal coverage.

[0004] To achieve the above technical objectives, the technical solution of the present invention includes:

[0005] A method for placing a feed source for a reconfigurable refractive metasurface antenna, applicable to communication between a base station and a user equipped with a reconfigurable refractive metasurface, the specific steps of the method including:

[0006] 1) Maintain feed angle T i-1 Unchanged, based on the user's received signal-to-noise ratio γ i By defining coverage, we obtain the optimal coverage S. i and the corresponding feed position Q i , where i is the iteration number.

[0007] 2) Maintain feed position Q i Unchanged, based on the user's received signal-to-noise ratio γ′ i By defining the coverage, we obtain the optimal coverage S′. i and the corresponding feed angle T i ;

[0008] 3) When the optimal coverage S′ i With optimal coverage S′ i+1 When the difference is less than a preset threshold, the optimal feed position Qi and the optimal feed angle T are obtained. i ;

[0009] 4) Use the optimal feed position Q i With the optimal feed angle T i Then, place the feed source.

[0010] Furthermore, the feed angles include: pitch angle, azimuth angle, and rotation angle.

[0011] Furthermore, the coordinates of the feed position and the feed angle are obtained through the following steps:

[0012] 1) Construct a Cartesian coordinate system with the center of the reflective metasurface as the origin, the directions of the two sides of the metasurface as the x and y axes respectively, and the direction perpendicular to the metasurface as the z axis;

[0013] 2) Based on the Cartesian coordinate system, obtain the coordinates of the feed position and the feed angle.

[0014] Furthermore, the user-received signal-to-noise ratio γ is obtained through the following steps. i :

[0015] 1) Based on the feed angle T i-1 This yields the product of the antenna gains of the transmitting and receiving antennas in the directions of each radiating element (m,n).

[0016] 2) Obtain the coordinates F of the radiating element (m,n) in the Cartesian coordinate system. m,n ;

[0017] 3) Based on feed position Q i Coordinate F m,n Calculate the distance from the feed source to the radiating element (m,n) based on the user's location. Spacing between the user and the radiation element (m,n)

[0018] 4) Based on the size s of the radiating element (m,n) M,N Antenna gain product spacing Spacing Calculate the channel gain of the radiating element (m,n).

[0019] 5) Based on the gain of each channel With refractive index Obtain the channel h from the feed to the user i ;

[0020] 6) Based on channel h i The variance of the feed power P and the additive white Gaussian noise received by the user Obtain the user's received signal-to-noise ratio γ i .

[0021] Furthermore, the refractive index The calculation methods include: calculations based on refraction amplitude and phase shift.

[0022] Furthermore, the method for calculating the refraction amplitude includes: using the incident angle from the feed source to the radiating element (m,n). get.

[0023] Furthermore, the phase shift is in the range of (0, 2π).

[0024] Furthermore, the definition of coverage includes: γ ≥ γ th =γ s L mar Where γ is the user's received signal-to-noise ratio, γ th For the user's received signal-to-noise ratio threshold, γ s For user sensitivity, L mar This is the penetration loss margin.

[0025] A method for placing a feed source for a reconfigurable refractive metasurface antenna is provided. The application scenarios of this method include communication between a base station equipped with a reconfigurable refractive metasurface and a user. The specific steps of the method include:

[0026] 1) Maintain feed position Q i-1 Unchanged, depending on the user's received signal-to-noise ratio γ i By defining the coverage, we obtain the optimal coverage S. i and the corresponding feed angle T i , where i is the iteration number.

[0027] 2) Maintain feed angle T i Unchanged, based on the user's received signal-to-noise ratio γ′ i By defining the coverage, we obtain the optimal coverage S′. i and the corresponding feed position Q i ;

[0028] 3) When the optimal coverage S′ i With optimal coverage S′ i+1 When the difference is less than a preset threshold, the optimal feed position Q is obtained. i With the optimal feed angle T i ;

[0029] 4) Use the optimal feed position Q i With the optimal feed angle T i Then, place the feed source.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. Since reconfigurable refractive metasurface antennas do not have the problem of feed obstruction, their radiation efficiency is higher than that of traditional reconfigurable reflective metasurface antennas.

[0032] 2. Maximize the coverage of base stations. Attached Figure Description

[0033] Figure 1 A schematic diagram of a reconfigurable refractive metasurface.

[0034] Figure 2 The method flowchart of the present invention.

[0035] Figure 3 A schematic diagram of a narrowband downlink network.

[0036] Figure 4 The Cartesian coordinate system established in this invention. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only specific embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] A reconfigurable refractive metasurface antenna consists of a feed source and a refractive metasurface. For example... Figure 1 As shown, the refractive metasurface is an array of multiple subwavelength elements. Each element has a PIN diode, which can be switched between ON and OFF by adjusting the bias voltage across it. When a signal is incident on each element, it undergoes refraction. By adjusting the state of the diodes on the elements, the phase of the refracted wave can be changed. The beamforming process of this reconfigurable refractive metasurface antenna is as follows: the signal emitted by the feed is refracted when it is incident on each element. During this refraction process, the metasurface elements apply a certain phase shift to the signal. By adjusting the bias voltage on the diodes, the refraction phase shift of the elements can be appropriately set, thereby achieving beamforming.

[0039] This invention optimizes the position (x) of the feed source relative to the transmission metasurface by jointly optimizing the position of the feed source. f ,y f ,z f ) and the direction of the feed (θ) f ,φ f ,α f), to place the reconfigurable refractive metasurface antenna feed, such as Figure 2 As shown, it includes:

[0040] 1) Keep the feed direction unchanged and use mathematical methods to optimize the position of the feed relative to the metasurface;

[0041] 2) Keep the position of the feed source relative to the metasurface unchanged, and optimize the orientation of the feed source using mathematical methods;

[0042] 3) Repeat step 1) until the difference in coverage between two adjacent iterations is less than a preset threshold.

[0043] like Figure 3 As shown, this embodiment is a narrowband downlink network containing one user and one base station. For beamforming, the base station employs a reconfigurable refractive metasurface antenna to effectively serve users within a 120-degree sector directly opposite the antenna. Assume the refractive metasurface contains M*N elements, each element having a size of s. M ×s N Let A denote the refraction amplitude and phase shift of the (m,n)th element. m,n and The refractive index of this unit can then be written as: Where the refraction amplitude A m,n It can be modeled as This represents the angle of incidence from the feed to the element (m,n). We also assume that regardless of the angle of incidence, the phase shift of the element can vary within the range (0, 2π) when the state of the element changes. The position of the feed relative to the metasurface can be described by the coordinates of the feed center and the feed pitch, azimuth, and rotation angles. For ease of description, we construct a Cartesian coordinate system with the center of the metasurface as the origin, the directions of the two sides of the metasurface as the x and y axes respectively, and the direction perpendicular to the metasurface as the z axis, as follows: Figure 4 As shown. The coordinates of the feed center are marked as (x... f ,y f ,z f The pitch angle, azimuth angle, and rotation angle of the feed are denoted as (θ). f ,φ f ,α f ).

[0044] Suppose the channel from the base station feed to the user consists of M×N metasurface-based channels, where the (m,n)th channel represents the channel from the feed through the (m,n)th metasurface unit to the user. The channel gain of the (m,n)th metasurface-based channel can be expressed as:

[0045]

[0046] Where λ represents the wavelength corresponding to the carrier frequency, G m,n This represents the product of the antenna gains of the transmitting and receiving antennas in the (m,n) direction, which is affected by the elevation, azimuth, and rotation angles of the feed. α represents the path loss factor. m,n and d m,n dm and nn represent the distance from the feed to the cell (m,n) and the distance from the user to the cell (m,n), respectively. Since our goal is to derive the coverage within the sector, we focus on finding the edges of the coverage, so we assume the user is in the far field of the metasurface. Therefore, we have dm. m,n =d, where d represents the distance from the user to the center of the metasurface. The distance from the base station to the cell can be further written as...

[0047]

[0048] Among them, (x m,n ,y m,n ) are the coordinates of the (m,n)th metasurface unit.

[0049] In summary, the channel from the feeder to the user can be written as follows:

[0050]

[0051] The user's received signal-to-noise ratio can be expressed as...

[0052]

[0053] Where P and σ 2 These represent the transmit power of the feed and the variance of the additive white Gaussian noise received by the user, respectively.

[0054] We define the coverage of a base station within a specified sector as: the area where the user's received signal-to-noise ratio (SNR) is higher than a certain threshold γ. th ,Right now

[0055] γ≥γ th =γ s L mar ,

[0056] Where, γ s This represents user sensitivity, L mar This represents the penetration loss margin. Based on the expression for signal-to-noise ratio and the definition of coverage, we can derive the relationship between coverage and feed hood deployment.

[0057] In a way that is easy to understand, the present invention can also first keep the position of the feed source relative to the metasurface unchanged, optimize the direction of the feed source using mathematical methods, then keep the direction of the feed source unchanged, optimize the position of the feed source relative to the metasurface using mathematical methods, until the difference in coverage between two adjacent iterations is less than a preset threshold.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for placing a reconfigurable refractive metasurface antenna feed, applicable to communication between a base station equipped with a reconfigurable refractive metasurface and a user, the specific steps of the method including: 1) Maintain feed angle Unchanged, based on the user's received signal-to-noise ratio By defining coverage, we obtain the optimal coverage. and the corresponding feed source location ,in, The coverage definition includes the number of iterations: , For users to receive signal-to-noise ratio, Set the signal-to-noise ratio threshold for user reception. For user sensitivity, This is the penetration loss margin; 2) Maintain the feed position Unchanged, based on the user's received signal-to-noise ratio By defining coverage, we obtain the optimal coverage. and the corresponding feed angle ; 3) When optimal coverage With optimal coverage When the difference is less than a preset threshold, the optimal feed position is obtained. With optimal feed angle ; 4) Use the optimal feed location With optimal feed angle Then, place the feed source.

2. The method as described in claim 1, characterized in that, The feed angles include: pitch angle, azimuth angle, and rotation angle.

3. The method as described in claim 1, characterized in that, The coordinates of the feed location and the feed angle are obtained through the following steps: 1) Construct a Cartesian coordinate system with the center of the reflective metasurface as the origin, the directions of the two sides of the metasurface as the x and y axes respectively, and the direction perpendicular to the metasurface as the z axis; 2) Based on the Cartesian coordinate system, obtain the coordinates of the feed position and the feed angle.

4. The method as described in claim 1, characterized in that, The user-received signal-to-noise ratio is obtained through the following steps. : 1) Based on the feed angle The transmitting and receiving antennas are obtained in each radiating element. Antenna gain product in direction ; 2) Obtaining radiation units Coordinates in the Cartesian coordinate system ; 3) Based on feed location ,coordinate Calculate the feed-to-radiation element based on the user's location. Spacing From user to radiation unit Spacing ; 4) Based on the radiation unit size Antenna gain product ,spacing Spacing Calculate the radiation element Channel gain ; 5) Based on the gain of each channel With refractive index This yields the channel from the feeder to the user. ; 6) Channel-based Feed source transmission power Variance of additive white Gaussian noise received by the user To obtain the user's received signal-to-noise ratio .

5. The method as described in claim 4, characterized in that, refractive index The calculation methods include: calculations based on refraction amplitude and phase shift.

6. The method as described in claim 5, characterized in that, Methods for calculating the refraction amplitude include: utilizing the data from the feed to the radiation element. angle of incidence get.

7. The method as described in claim 5, characterized in that, The phase shift is Within the range.

8. A method for placing a reconfigurable refractive metasurface antenna feed, the application scenario of which includes communication between a base station equipped with a reconfigurable refractive metasurface and a user, the specific steps of which include: 1) Maintain the feed position Unchanged, depending on the user's received signal-to-noise ratio By defining coverage, we obtain the optimal coverage. and the corresponding feed angle ,in, The coverage definition includes the number of iterations: ,in For users to receive signal-to-noise ratio, Set the signal-to-noise ratio threshold for user reception. For user sensitivity, This is the penetration loss margin; 2) Maintain feed angle Unchanged, depending on the user's received signal-to-noise ratio By defining coverage, we obtain the optimal coverage. and the corresponding feed source location ; 3) When optimal coverage With optimal coverage When the difference is less than a preset threshold, the optimal feed position is obtained. With optimal feed angle ; 4) Use the optimal feed location With optimal feed angle Then, place the feed source.

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