Holographic metasurface leaky-wave antenna with reconfigurable frequency and beam scanning

Abstract

The holographic metasurface leaky-wave antenna comprises a feed structure and a radiation structure which are stacked along the z axis of a three-dimensional coordinate, and the radiation structure comprises a dielectric substrate for radiation and two arrays which are printed on the upper surface of the dielectric substrate, are arranged in parallel and are composed of a plurality of radiation units. Wherein the radiation units in one array and the radiation units in the other array are distributed in a staggered manner; the radiation unit comprises a radiation patch etched with a rectangular annular gap, the radiation patch is divided into a rectangular patch located in the center and a rectangular annular patch nested with the rectangular patch by the rectangular annular gap, and a source device is loaded between the rectangular patch and the rectangular annular patch. According to the invention, the frequency reconfigurable characteristic of the radiation unit is realized by adjusting the voltage at the two ends of the active device; by adjusting the radiation states of the two radiation unit arrays, the beam scanning characteristics of the antenna under different frequencies of the radiation units are realized, and the defect that only fixed-frequency beam scanning can be realized in the prior art is overcome.

Description

Technical Field

[0001] The present invention belongs to the field of microwave technology and relates to a metasurface antenna, in particular to a frequency-reconfigurable metasurface beam scanning antenna, which can be used in the field of wireless communications. Background Art

[0002] Leaky wave antenna is a special antenna structure that realizes radiation based on the traveling wave mode. Its basic principle is to use the electromagnetic traveling wave propagating along the antenna structure to gradually leak part of the energy into the free space to form a radiation beam. Traditional leaky wave antennas have a frequency scanning characteristic when performing beam scanning, that is, its beam pointing angle changes with the different operating frequencies. When the antenna needs to perform beam scanning at a fixed operating frequency, it is often difficult to achieve.

[0003] The active holographic leaky wave antenna combines the holographic metasurface theory with the leaky wave antenna technology. The array distribution state of the leaky wave antenna at different beam pointing directions is determined according to the holographic theory formula, and the active device is controlled to make the array unit reach the corresponding state at different beam pointing directions, so as to realize the beam scanning characteristics of the antenna at a fixed frequency. However, such antennas can usually only achieve good performance in a narrow working frequency band, and the working frequency is often close to the point frequency, which is difficult to effectively meet the needs of multi-band or wide-band applications, limiting its adaptability and flexibility in complex communication environments. For example, the patent application with the application publication number CN 116231305A and the name "Cylindrical conformal active metasurface antenna based on amplitude control" discloses a cylindrical conformal active metasurface antenna based on amplitude control, including a feeding structure and a radiating structure, wherein the radiating structure includes a dielectric substrate and a radiating patch printed on the upper surface of the dielectric substrate, and the radiation intensity of the radiating patch is controlled by a PIN diode to realize the beam scanning of the cylindrical conformal active metasurface. However, since the radiating unit of the antenna can only achieve the switching effect of the radiation state at a fixed operating frequency, the antenna can only achieve beam scanning characteristics at a single frequency point. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies in the above-mentioned technology and to propose a holographic metasurface leaky-wave antenna with frequency reconfigurable beam scanning, which is used to solve the technical problem in the prior art that the application range is narrow due to the fact that only fixed-frequency beam scanning can be achieved.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention includes a feeding structure 1 and a radiation structure 2 stacked along the z-axis of the three-dimensional coordinate. The radiation structure 2 includes a dielectric substrate 21 for radiation and two arrays composed of multiple radiation units 22 arranged in parallel printed on its upper surface, wherein the radiation units 22 in one array are staggered with those in the other array; the radiation unit 22 includes a radiation patch 221 etched with a rectangular annular gap, and the rectangular annular gap divides the radiation patch 221 into a rectangular patch located in the center and a rectangular annular patch nested therewith; an active device 222 is respectively arranged between each side of the rectangular patch and the rectangular annular patch.

[0006] The frequency reconfigurable characteristic of the radiation unit 22 is achieved by adjusting the voltage across the active device 222 ; the beam scanning characteristic of the antenna at different frequencies of the radiation unit 22 is achieved by adjusting the radiation state of the two radiation unit arrays.

[0007] As an optimization, the feeding structure 1 includes a dielectric substrate 11 for feeding and a first metal patch 12 and a second metal patch 13 printed on the upper and lower surfaces thereof; two parallel-arranged coupling slot arrays are etched on the first metal patch 12, wherein one array is staggered with the coupling slots 121 in the other array, and a metallized via array 122 for connecting the first metal patch 12 and the second metal patch 13 is provided on the outer side of each of the two coupling slot arrays; the coupling slots 121 in the two coupling slot arrays correspond to the positions of the radiation units 22 in the two radiation unit arrays.

[0008] As an optimization, the coupling slot 121 adopts an I-shaped coupling slot structure, and its two lateral branches are parallel to the metallized via array 122 .

[0009] As an optimization, the center of the coupling slot 121 and the center of the rectangular patch in the radiation unit 22 corresponding to the position of the coupling slot 121 are both located on an axis parallel to the three-dimensional coordinate z-axis.

[0010] As an optimization, the first metal patch 12 has two ends parallel to the coupling slot array, each of which is spliced ​​with a trapezoidal metal patch 14, which is used for impedance matching with the feed input port and the load port, respectively.

[0011] As an optimization, the radiation dielectric substrate 21 is provided with a second metallized via 224 for feeding the rectangular patch, and a first metallized via 223 and a third metallized via 225 whose lower ends are connected to an external bias circuit, the upper end of the first metallized via 223 is connected to the rectangular ring patch, and the third metallized via 225 is connected to the second metallized via 224.

[0012] As an optimization, the frequency reconfigurable characteristic of the radiation unit 22 is realized by controlling the input voltage of the external bias circuit to change the voltage between the rectangular patch and the rectangular ring patch, thereby changing the voltage across the active device 222 to make it present a different working state, thereby changing the equivalent circuit parameters of the radiation unit 22, and realizing the frequency reconfigurable characteristic of the radiation unit 22.

[0013] As an optimization, the beam scanning characteristics of the antenna at different frequencies of the radiation unit 22 are realized by controlling the input voltage of the external bias circuit to change the working state of the active device 222, thereby changing the radiation intensity of the radiation unit 22, so that the radiation unit array presents different radiation intensity distributions, thereby realizing the beam scanning characteristics of the holographic metasurface leaky wave antenna with frequency reconfigurable beam scanning at different frequencies.

[0014] As an optimization, the radiation unit array, wherein the radiation intensity I of the nth radiation unit n The calculation formula is:

[0015] I n =cos(k g x n -k0sin(θ0))

[0016]

[0017] Where λ0 is the wavelength corresponding to the operating frequency of the holographic metasurface leaky-wave antenna with frequency reconfigurable beam scanning, ε r is the relative dielectric constant of the feed medium substrate, w is the spacing between two rows of metallized via arrays, c is the distance between the centers of two adjacent metallized vias in the metallized via array, d is the diameter of the metallized via in the metallized via array, and x n is the distance of the nth radiating unit relative to the starting radiating patch in the radiating array, θ0 is the beam pointing angle of the holographic metasurface leaky wave antenna with frequency reconfigurable beam scanning, k0 is the propagation constant in free space, I n Represents the radiation intensity of the nth radiation unit, where n∈[1,N], N represents the total number of radiation units, and N≥2.

[0018] As an optimization, the active device 222 is a varactor diode.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] Two arrays consisting of multiple radiation units arranged in parallel are printed on a dielectric substrate in the radiation structure of the present invention, wherein the radiation units in one array are staggered with those in the other array; a rectangular annular gap is etched on the radiation patch in the radiation unit, dividing the radiation patch into a rectangular patch located in the center and a rectangular annular patch nested therewith; the frequency reconfigurable characteristic of the radiation unit is achieved by adjusting the voltage at both ends of the active device; the beam scanning characteristic of the antenna at different frequencies of the radiation unit is achieved by adjusting the radiation state of the two radiation unit arrays, thereby avoiding the defect that the prior art can only achieve fixed-frequency beam scanning, and effectively broadening the scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 It is a schematic diagram of the feeding structure of the present invention;

[0023] Figure 3 is a schematic diagram of the coupling gap structure of the present invention;

[0024] Figure 4 It is a schematic diagram of the structure of the radiation unit of the present invention;

[0025] Figure 5 It is the simulation result of the transmission coefficient of the radiation unit of the present invention at different operating frequencies;

[0026] Figure 6 It is a schematic diagram of array states corresponding to different beam pointing directions when the operating frequencies of the present invention are 2.3 GHz and 2.55 GHz;

[0027] Figure 7 It is the electric field distribution diagram of the radiation unit of the present invention when the operating frequency is 2.3 GHz and 2.55 GHz;

[0028] Figure 8 It is the beam scanning simulation result of the present invention when the working frequency is 2.3GHz;

[0029] Fig. 9 It is the beam scanning simulation result of the present invention when the working frequency is 2.55GHz; DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0031] Embodiment 1: This embodiment realizes the operation of the radiation patch at different frequencies by controlling the voltage across the varactor diode, so as to realize the beam scanning characteristics of the holographic metasurface leaky wave antenna with frequency reconfigurable beam scanning at multiple frequencies.

[0032] Reference Figure 1 The technical solution adopted by the present invention includes a feeding structure 1 and a radiating structure 2 stacked up and down, wherein the radiating structure 2 includes a radiating dielectric substrate 21 and two parallel linear arrays of radiating units printed on its upper surface, the radiating dielectric substrate 21 is 3 mm thick and has a relative dielectric constant of 6.15; the radiating units 22 in one array are staggered with those in another array, each array has 21 radiating units, and the spacing between two adjacent radiating units is 13 mm; the radiating unit 22 includes a radiating patch 221 etched with a rectangular annular gap, and the radiating patch 221 is divided into a central A rectangular patch and a rectangular annular patch nested therewith; an active device 222 is respectively arranged between each side of the rectangular patch and the rectangular annular patch; the rectangular annular patch is connected to the first metallized via through an inductor, and when the first metallized via is energized, the rectangular annular patch will have the same voltage as the first metallized via; the rectangular patch is connected to the second metallized via through an inductor, the second metallized via is connected to the third metallized via through a DC feeder, the third metallized via is connected to an external bias circuit, and when the third metallized via is energized, the rectangular patch will have the same voltage as the third metallized via. By controlling the input voltage of the external bias circuit, the voltage between the rectangular patch and the rectangular annular patch is changed, and then the voltage at both ends of the active device 222 is changed to make it present a different working state, thereby changing the equivalent circuit parameters of the radiation unit 22, and finally realizing the frequency reconfigurable characteristics of the radiation unit 22.

[0033] Reference Figure 2 The feeding structure 1 comprises a feeding dielectric substrate 11 and a first metal patch 12 and a second metal patch 13 printed on the upper and lower surfaces thereof; two parallel coupled slot arrays are etched on the first metal patch 12, wherein the coupling slots 121 in one array are staggered with the coupling slots in the other array, and the spacing between two adjacent coupling slots in each array is 13 mm, and metallized via arrays 122 connecting the first metal patch 12 and the second metal patch 13 are respectively arranged on the outer sides of the two coupling slot arrays, the spacing between the two rows of metallized via arrays 122 is 45 mm, the spacing between two adjacent metallized vias is 2 mm, and the diameter of the metallized via is 1.6 mm; the thickness of the feeding dielectric substrate 11 is 1.5 mm, and the relative dielectric constant is 6.15.

[0034] Reference Figure 3 The structural parameters of the coupling gap 121 are: transverse branch length l1=7mm, transverse branch width w1=1mm, longitudinal branch length l2=3.5mm, and longitudinal branch width w2=8mm.

[0035] Reference Figure 4The structural parameters of the radiation patch 221 are as follows: the length of the rectangular ring patch a1=22mm, the width of the rectangular ring patch b1=25mm, the length of the rectangular patch a2=15mm, the width of the rectangular patch b2=15mm; the spacing between the rectangular ring patch and the rectangular patch g=0.5mm.

[0036] The working principle of the invention is:

[0037] The principle of the frequency reconfiguration of the present invention is as follows: the radiation structure of the frequency reconfigurable beam scanning holographic metasurface leaky wave antenna of the present invention can be regarded as a microstrip antenna array, wherein the equivalent circuit model of the radiating unit determines its operating frequency, and when the voltage across the varactor changes, the capacitance of its equivalent circuit changes, resulting in a change in the equivalent circuit of the radiating unit, and its operating frequency also changes accordingly. At different operating frequencies, for the varactor, there are two sets of capacitance values ​​representing the radiation and cutoff of the radiating unit at the frequency. When the operating frequency is determined, it is only necessary to adjust the working state of the varactor to the corresponding capacitance value, so that the varactor can control the radiation and cutoff of the radiating unit at the new operating frequency, thereby realizing the frequency reconfigurable characteristics of the frequency reconfigurable beam scanning holographic metasurface leaky wave antenna.

[0038] The principle of the beam scanning of the present invention is as follows: the frequency reconfigurable beam scanning holographic metasurface leaky wave antenna of the present invention can be regarded as a traveling wave antenna. For a planar traveling wave antenna, there is an inherent phase difference k between the radiation units. g x n , x n is the spacing between adjacent radiating patches. Therefore, when designing the antenna, the input voltage of the external bias circuit is controlled to control the radiation intensity of the radiating patches at different positions, so that the antenna beam is pointed in the same direction as the desired direction. For a traveling wave antenna, when its beam pointing is θ0, according to the holographic principle, the calculation formula for the radiation intensity of the nth radiating unit is:

[0039] I n =cos(k g x n -k0sin(θ0))

[0040]

[0041] Where λ0 is the operating frequency wavelength of the frequency reconfigurable beam scanning holographic metasurface leaky wave antenna, ε r is the relative dielectric constant of the feed medium substrate, w is the spacing between two rows of metallized via arrays, c is the distance between the centers of two adjacent metallized vias in the metallized via array, d is the diameter of the metallized via in the metallized via array, and x nis the distance of the nth radiating unit relative to the starting radiating patch in the radiating array, θ0 is the beam pointing angle of the holographic metasurface leaky wave antenna with frequency reconfigurable beam scanning, k0 is the propagation constant in free space, I n Represents the radiation intensity of the nth unit, where n∈[1,N], N represents the total number of radiation units, and N≥2.

[0042] The radiation intensity of the radiation patch obtained in the above formula is a continuous value, while the state of the active device in the present invention uses only two states to represent the radiation and cutoff of the radiation unit at each operating frequency, and only simulates two radiation intensities. Therefore, it is necessary to perform discrete processing on the continuous radiation intensity of the radiation unit; therefore, the working state of the varactor diode on the nth radiation unit is:

[0043]

[0044] Among them, m(n) represents the working state of the radiation unit, 1 represents that the varactor diode puts the unit in the radiation state at the working frequency, and 0 represents that the varactor diode puts the radiation unit in the cut-off state at the working frequency.

[0045] The technical effects of the present invention are further illustrated below through simulation experiments.

[0046] 1. Simulation conditions and contents:

[0047] Simulation 1: The transmission coefficient of the radiation unit of Example 1 of the present invention is simulated using the simulation software CST MICROWAVE STUDIO. The results are as follows: Figure 5 As shown;

[0048] Simulation 2, the array radiation intensity distribution state corresponding to the frequency reconfigurable beam scanning holographic metasurface leaky wave antenna in the embodiment of the present invention is simulated at different beam pointing frequencies of 2.3 GHz and 2.55 GHz, and the results are as follows: Figure 6 (a) and Figure 6 (b) as shown.

[0049] Simulation 3 simulates the electric field distribution of the radiation unit in the embodiment of the present invention at frequencies of 2.3 GHz and 2.55 GHz. The results are as follows: Figure 7 (a) and Figure 7 (b) as shown.

[0050] Simulation 4 simulates the beam scanning characteristics of the frequency reconfigurable beam scanning holographic metasurface leaky wave antenna in the embodiment of the present invention at the operating frequency of 2.3 GHz, and the results are as follows: Figure 8 (a) and Figure 8 (b) as shown:

[0051] Simulation 5 simulates the beam scanning characteristics of the frequency reconfigurable beam scanning holographic metasurface leaky wave antenna in the embodiment of the present invention at the operating frequency of 2.55 GHz, and the results are as follows: Fig. 9 (a) and Fig. 9 (b)

[0052] 2. Analysis of simulation results:

[0053] Reference Figure 5 In the embodiment of the present invention, the transmission coefficient of the radiation unit under different working states of the varactor diode is simulated. At different working frequencies, the difference in the transmission coefficients of the two states is greater than 0.7dB, which proves that the varactor diode can achieve control over the radiation patch at multiple working frequencies.

[0054] Reference Figure 6 (a) and Figure 6 (b) In the embodiment of the present invention, the radiation intensity distribution state of the radiation unit array at 2.3 GHz and 2.55 GHz has a corresponding relationship with the beam pointing angle. At different frequencies, different beam pointing angles correspond to different radiation intensity distribution states.

[0055] Reference Figure 7 (a), when the radiating unit in the embodiment of the present invention operates at 2.3 GHz, the electric field is mainly distributed around the rectangular ring patch, which proves that the rectangular ring patch plays a major role in contributing to the antenna radiation at the operating frequency of 2.3 GHz.

[0056] Reference Figure 7 (b) When the radiation unit in the embodiment of the present invention operates at 2.55 GHz, the electric field is mainly distributed around the rectangular patch, which proves that the rectangular patch plays a major role in contributing to the antenna radiation at the operating frequency of 2.55 GHz.

[0057] Reference Figure 8 (a) and Figure 8 (b) In the embodiment of the present invention, a beam scanning simulation is performed on a frequency reconfigurable beam scanning holographic metasurface leaky wave antenna at 2.3 GHz. It can be seen that the antenna can achieve beam scanning characteristics at 2.3 GHz.

[0058] Reference Fig. 9 (a) and Fig. 9 (b) In the embodiment of the present invention, a beam scanning simulation is performed on a frequency reconfigurable beam scanning holographic metasurface leaky wave antenna at 2.55 GHz. It can be seen that the antenna can achieve beam scanning characteristics at 2.55 GHz.

[0059] The above description is only a preferred embodiment of the present invention and does not constitute a limitation to the present invention. A person skilled in the art may make several modifications and improvements without departing from the innovative concept of the present invention, but these changes shall all fall within the scope of protection of the present invention.

Claims

1. A frequency reconfigurable beam scanning holographic metasurface leaky wave antenna, comprising a feeding structure (1) and a radiation structure (2) stacked along a three-dimensional coordinate z-axis; characterized in that: The radiation structure (2) comprises a radiation dielectric substrate (21) and two arrays composed of a plurality of radiation units (22) printed on the upper surface thereof and arranged in parallel, wherein the radiation units (22) in one array are arranged alternately with those in the other array; the radiation units (22) comprise radiation patches (221) etched with rectangular annular gaps, wherein the rectangular annular gaps divide the radiation patches (221) into a rectangular patch located in the center and a rectangular annular patch nested therewith; and an active device (222) is respectively arranged between each side of the rectangular patch and the rectangular annular patch. The frequency reconfigurable characteristic of the radiation unit (22) is achieved by adjusting the voltage at both ends of the active device (222); and the beam scanning characteristic of the antenna at different frequencies of the radiation unit (22) is achieved by adjusting the radiation state of the two radiation unit arrays.

2. The antenna according to claim 1, characterized in that The feeding structure (1) comprises a feeding dielectric substrate (11) and a first metal patch (12) and a second metal patch (13) printed on the upper and lower surfaces thereof; the first metal patch (12) is etched with two parallelly arranged coupling slot arrays, wherein one array is staggered with the coupling slots (121) in the other array, and metallized via arrays (122) for connecting the first metal patch (12) and the second metal patch (13) are respectively arranged on the outer sides of the two coupling slot arrays; the coupling slots (121) in the two coupling slot arrays correspond to the positions of the radiation units (22) in the two radiation unit arrays.

3. The antenna according to claim 2, characterized in that: The coupling slot (121) adopts an I-shaped coupling slot structure, and two lateral branches thereof are parallel to the metallized via array (122).

4. The antenna according to claim 3, characterized in that: The coupling slot (121), the center of which and the center of the rectangular patch in the radiation unit (22) corresponding to the position of the coupling slot (121) are both located on an axis parallel to the three-dimensional coordinate z-axis.

5. The antenna according to claim 2, characterized in that: The first metal patch (12) has two ends parallel to the coupling slot array, each of which is spliced ​​with a trapezoidal metal patch (14), which is used for impedance matching with the feed input port and the load port respectively.

6. The antenna according to claim 1, characterized in that The radiation dielectric substrate (21) is provided with a second metallized via (224) for feeding the rectangular patch, and a first metallized via (223) and a third metallized via (225) whose lower ends are connected to an external bias circuit, the upper end of the first metallized via (223) is connected to the rectangular ring-shaped patch, and the third metallized via (225) is connected to the second metallized via (224).

7. The antenna according to claim 6, characterized in that The frequency reconfigurable characteristic of the radiation unit (22) is realized by controlling the input voltage of the external bias circuit to change the voltage between the rectangular patch and the rectangular ring patch, thereby changing the voltage at both ends of the active device (222) to make it present a different working state, thereby changing the equivalent circuit parameters of the radiation unit (22), thereby realizing the frequency reconfigurable characteristic of the radiation unit (22).

8. The antenna according to claim 7, characterized in that: The antenna has beam scanning characteristics at different frequencies of the radiation unit (22), and its realization principle is that by controlling the input voltage of the external bias circuit, the working state of the active device (222) is changed, thereby changing the radiation intensity of the radiation unit (22), so that the radiation unit array presents different radiation intensity distributions, and realizing the beam scanning characteristics of the holographic metasurface leaky wave antenna with frequency reconfigurable beam scanning at different frequencies.

9. The antenna according to claim 8, characterized in that The radiation unit array, wherein the radiation intensity I of the nth radiation unit n The calculation formula is: I n =cos(k g x n -k0sin(θ0)) Where λ0 is the wavelength corresponding to the operating frequency of the holographic metasurface leaky-wave antenna with frequency reconfigurable beam scanning, ε r is the relative dielectric constant of the feed medium substrate, w is the spacing between two rows of metallized via arrays, c is the distance between the centers of two adjacent metallized vias in the metallized via array, d is the diameter of the metallized via in the metallized via array, and x n is the distance between the nth radiating element and the starting radiating element in the radiating array, θ0 is the beam pointing angle of the holographic metasurface leaky wave antenna with frequency reconfigurable beam scanning, k0 is the propagation constant in free space, I n Represents the radiation intensity of the nth radiation unit, where n∈[1,N], N represents the total number of radiation units, and N≥2.

10. The antenna according to claim 1, characterized in that: The active device (222) is a varactor diode.

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