阅读说明：本技术 基于二氧化钒薄膜的频率可重构超表面天线及通信设备 (Frequency-reconfigurable super-surface antenna based on vanadium dioxide film and communication equipment ) 是由 杨琬琛 李靖豪 车文荃 薛泉 魏立 于 2021-05-11 设计创作，主要内容包括：本发明公开了一种基于二氧化钒薄膜的频率可重构超表面天线及通信设备,包括介质基板,所述介质基板的上表面印制金属超表面结构,介质基板下表面印制金属地板,所述金属地板刻蚀环形缝隙,金属地板与设置在其下方的阶梯状矩形波导连接。该天线能够在低剖面的情况下,实现频率可重构的高增益性能。(The invention discloses a frequency reconfigurable super-surface antenna based on a vanadium dioxide film and communication equipment. The antenna can realize high gain performance with reconfigurable frequency under the condition of low profile.)

1. The frequency-reconfigurable super-surface antenna based on the vanadium dioxide film is characterized by comprising a dielectric substrate, wherein a metal super-surface structure is printed on the upper surface of the dielectric substrate, a metal floor is printed on the lower surface of the dielectric substrate, an annular gap is etched on the metal floor, and the metal floor is connected with a stepped rectangular waveguide arranged below the metal floor.

2. The frequency reconfigurable super-surface antenna according to claim 1, wherein the metal super-surface structure comprises N x M super-surface units arranged in an array, each super-surface unit comprises two rectangular patches, each rectangular patch is plated with a vanadium dioxide film on one side in the vertical dimension, and the two vanadium dioxide films are connected through a microstrip branch; in the horizontal dimension, adjacent super-surface units are connected by microstrip branches.

3. The frequency reconfigurable super-surface antenna according to claim 2, wherein the vanadium dioxide thin film adopts an interdigital structure.

4. The frequency reconfigurable super-surface antenna according to claim 1, further comprising a bias circuit, wherein the bias circuit is arranged on two sides of the metal super-surface structure and comprises a sector branch and a metal rectangular patch, and the metal super-surface structure is connected with the metal rectangular patch through a pair of sector branches.

5. The frequency reconfigurable super surface antenna according to any one of claims 1 to 4, wherein the annular slot is a bone-type slot.

6. The frequency reconfigurable super surface antenna according to any one of claims 1 to 4, wherein the stepped rectangular waveguide is loaded with a double ridge structure.

7. The frequency reconfigurable super surface antenna of claim 2, wherein two rectangular patches are spaced 2 x L apart in the vertical dimension₁，L₁Is 0.0002 lambda to 0.02 lambda, lambda being the free space wavelength.

8. The frequency reconfigurable super-surface antenna according to claim 1, wherein when the vanadium dioxide thin film is a conductor, the antenna operates at 28 GHz: the current flows around the outer side of the annular gap, and the electric fields in the gap are vertical, so that the super-surface antenna is excited; when the vanadium dioxide film is an insulator, the antenna works at 38 GHz: the gap is considered to be a boundary from the midpoint of the vertical dimension, and is divided into an upper gap and a lower gap, current flows around the outer side of each gap, and the upper gap and the lower gap are in the same phase and are in the vertical direction.

9. The frequency reconfigurable super surface antenna according to claim 3, wherein the width W of the interdigital vanadium dioxide thin film₁0.0008 lambda to 0.08 lambda and a length L₃0.0005 lambda-0.05 lambda, 0.000001 lambda-0.001 lambda as free space wavelength.

10. A communication device comprising a frequency reconfigurable super surface antenna according to any of claims 1-9.

Technical Field

The invention relates to the field of antennas, in particular to a frequency reconfigurable super-surface antenna based on a vanadium dioxide film and communication equipment.

Background

With the development of wireless networks, wireless data services are growing explosively, and in order to meet the demands of wireless communication application scenarios, future communication systems need to provide larger bandwidths and higher spectral efficiencies. The millimeter wave frequency band attracts the public attention with the advantages of extremely wide bandwidth, high transmission quality and the like. With the proposal of reconfigurable technology, a new thought and direction are provided for the design of the antenna, and the function of a plurality of antennas can be realized in one antenna aperture by using a mechanical or electrical regulation mode. The antenna has the following advantages:

(1) the multiple antennas share one caliber, so that the size of the system is reduced, the structure is simplified and compact, and the integration on the current wireless communication equipment is facilitated.

(2) The antenna is dynamically adjusted in a mechanical or electric regulation mode, so that the antenna is more flexible and variable.

(3) The electromagnetic interference of the equipment is reduced, and the electromagnetic compatibility between the load and the antenna is improved.

The reconfigurable technology can be divided into polarization reconfigurable, directional diagram reconfigurable and frequency reconfigurable according to different functions. The reconfigurable system needs to load one or more controllable devices to realize function switching, the traditional controllable devices are mostly semiconductor switches such as PIN diodes, varactor diodes and the like, but the applicable frequency is low, the insertion loss in a millimeter wave frequency band is too large, the loss reaches 5dB at 40GHz, and the reconfigurable system cannot be normally used in a millimeter wave band. In recent years, some new controllable devices have been proposed, such as MEMS switches, phase change materials, etc. The MEMS switch has low switching speed, high energy consumption, low reliability and is easily influenced by external factors such as stress, humidity, high temperature and high pressure and the like; performance of germanium telluride (GeTe) and VO₂The films are similar, but the conversion speed is slow, and the power consumption is large; the graphene has extremely high requirements on the preparation process, no mature single-layer graphene film preparation method exists at present, and the regulation and control voltage of the graphene is also higher in requirement. In order to realize a millimeter wave reconfigurable system, it is important to find a switching device applicable to millimeter waves.

Disclosure of Invention

In order to overcome the defects and shortcomings of the prior art, the primary object of the present invention is to provide a frequency reconfigurable super-surface antenna based on a vanadium dioxide thin film, which can realize a frequency reconfigurable high-gain performance under the condition of a low profile.

It is a secondary object of the present invention to provide a communication device.

The invention mainly aims to adopt the following technical scheme:

a frequency reconfigurable super-surface antenna based on a vanadium dioxide film comprises a dielectric substrate, wherein a metal super-surface structure is printed on the upper surface of the dielectric substrate, a metal floor is printed on the lower surface of the dielectric substrate, an annular gap is etched on the metal floor, and the metal floor is connected with a stepped rectangular waveguide arranged below the metal floor.

Furthermore, the metal super-surface structure comprises N x M super-surface units arranged in an array, each super-surface unit comprises two rectangular patches, vanadium dioxide films are plated on opposite sides of the two rectangular patches in the vertical dimension, and the two vanadium dioxide films are connected through microstrip branches; in the horizontal dimension, adjacent super-surface units are connected by microstrip branches.

Further, the vanadium dioxide film adopts an interdigital structure.

The metal super-surface structure is connected with the metal rectangular patch through a pair of fan-shaped branches.

Further, the annular gap is a bone-shaped gap.

Further, the stepped rectangular waveguide is loaded with a double-ridge structure.

Further, the two rectangular patches are spaced 2 x L apart in the vertical dimension₁，L₁Is 0.0002 lambda to 0.02 lambda, lambda being the free space wavelength.

Further, when the vanadium dioxide film is a conductor, the antenna works at 28 GHz: the current flows around the outer side of the annular gap, and the electric fields in the gap are vertical, so that the super-surface antenna is excited; when the vanadium dioxide film is an insulator, the antenna works at 38 GHz: the gap is considered to be a boundary from the midpoint of the vertical dimension, and is divided into an upper gap and a lower gap, current flows around the outer side of each gap, and the upper gap and the lower gap are in the same phase and are in the vertical direction.

Further, the width W of the vanadium dioxide film with the interdigital structure₁0.0008 lambda to 0.08 lambda and a length L₃0.0005 lambda-0.05 lambda, 0.000001 lambda-0.001 lambda as free space wavelength.

The invention has the secondary purpose of adopting the following technical scheme:

a communication device is characterized by comprising the frequency reconfigurable super-surface antenna.

The invention has the beneficial effects that:

(1) according to the frequency tunable super-surface antenna based on the vanadium dioxide film, when the resistivity of the vanadium dioxide film is changed, the frequency tuning from 28G to 38G can be realized;

(2) compared with a semiconductor switch, an MEMS switch and other phase change materials used for a common reconfigurable antenna, the loss of vanadium dioxide is smaller, the switching speed is higher, and the isolation degree is higher;

(3) the frequency tunable super-surface structure based on the vanadium dioxide film has the characteristics of low section and thickness of only 0.14 lambda;

(4) the frequency tunable super-surface based on the vanadium dioxide film has the characteristic of high gain. When the vanadium dioxide film is in an insulating state, the maximum gain in the antenna band is 7.7 dB. When the vanadium dioxide film is in a conductor state, the maximum gain in the antenna band is 7.1 dB;

(5) the frequency-tunable super-surface antenna based on the vanadium dioxide film has the advantages of simple control circuit, strong controllability and very short switching time between two frequencies.

Drawings

FIG. 1 is a top view of a super surface unit of the present invention;

FIG. 2 is a top view of the present invention;

FIG. 3 is a three-dimensional view of the present invention;

FIG. 4 is a side view of the present invention;

FIG. 5 shows that the present invention is at VO₂Characteristic impedance Z in two states of thin film insulation and conduction₀A drawing;

FIG. 6 is a diagram of a coupling slot structure of the present invention;

FIG. 7(a) is a graph showing the current-electric field distribution when the coupling slot of the present invention is operated at 28 GHz;

FIG. 7(b) is a graph showing the current-electric field distribution when the coupling slot of the present invention is operated at 38 GHz;

FIG. 8(a) shows VO of the present invention₂A reflectance curve and a gain curve when the film is on and off;

FIG. 8(b) shows VO of the present invention₂A pattern when the film is on;

FIG. 8(c) shows VO of the present invention₂Pattern when the film is insulating.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited to these examples.

Example 1

As shown in fig. 1-3, the frequency reconfigurable super-surface antenna based on the vanadium dioxide film comprises a dielectric substrate 3, wherein the metal super-surface structure 2 is printed on the upper surface of the dielectric substrate in the center, and a metal floor 4 is arranged on the lower surface of the dielectric substrate 3.

The metal super-surface structure 2 is composed of N M super-surface units arranged in an array, the metal super-surface structure in the embodiment is composed of 6M 8 super-surface units, the super-surface units are identical in structure and are composed of two rectangular patches, the two rectangular patches are arranged in parallel in an up-and-down symmetrical mode, and the vanadium dioxide film 1 is plated on the opposite side of the two rectangular patches. As shown in figure 1, a vanadium dioxide coating film is arranged on one side of two adjacent rectangular patches, and the vanadium dioxide coating films on the two sides are connected through a microstrip branch. In the horizontal dimension, adjacent super-surface units are connected through microstrip branches. The vanadium dioxide film 1 adopts an interdigital structure, the resistance of the structure before phase change is low, and the bearing voltage on a film circuit is consistent under the condition of consistent dissipation powerThe film is low in cost, not easy to break down and more suitable for the condition that a plurality of films are connected in series. Due to VO₂VO is not completely considered as a conductor or insulator when the film is in both conductor and insulation₂The film will introduce resistance, inductance and capacitance when conducting, and resistance and capacitance when insulating. VO (vacuum vapor volume)₂The microstrip branches between the films introduce inductance and the distance between each set of patches is small, thus also forming capacitance. And finally, adding an equivalent inductor formed by current flowing through the metal patch, the metal column and the floor to another metal patch to form a resonant circuit with a super-surface structure.

Further, in the horizontal dimension, adjacent super-surface units 8 are connected through microstrip branches, and because the polarization direction of the antenna is orthogonal to the microstrip branches in the horizontal dimension, the introduction of the microstrip branches does not have obvious influence on the resonant frequency.

Further, as shown in fig. 2, the leftmost side and the rightmost side of the metal super-surface structure 2 are respectively connected with the metal rectangular patch through a microstrip branch, and a pair of metal fan-shaped patches is loaded at the branch close to the metal rectangular patch to form a bias circuit 7 with a filtering function. The fan-shaped branch knot can be equivalent to a capacitor, and can filter out radio frequency signals. The metal floor is engraved with an annular gap 9 and connected to a stepped rectangular waveguide 5 with a double ridge structure 6 underneath. The purpose of changing the standard rectangular waveguide into the stepped rectangular waveguide is to improve impedance matching, and the purpose of adding the double ridges is to widen the bandwidth and improve the impedance matching to a certain extent.

Further, the dielectric constant ε of the dielectric substrate 3_r2-20, length of 0.1-3 lambda, width of 0.5-5 lambda, and thickness of 0.01-0.1 lambda, wherein lambda is the free space wavelength corresponding to the center frequency.

Further, the length of the metal floor 4 is 0.1 λ - λ, and the width thereof is 0.5 λ -5 λ, wherein λ is a free space wavelength corresponding to the center frequency.

Further, as shown in fig. 2, the length W of the microstrip branch connected to the bias circuit and the metal super-surface structure 2₄，L₆，W₅Respectively is 0.05 lambda to lambda, 0.08 lambda to 1.2 lambdaThe width is 0.0005 lambda-0.05 lambda, and lambda is free space wavelength. The radius R of the fan-shaped patch is 0.001 lambda-0.1 lambda, and the angle is 30-135 deg. Length and width L of metal rectangular patch at DC feed₇All are 0.05 lambda-0.5 lambda, and lambda is free space wavelength.

Further, as shown in FIG. 1, the length L of the rectangle in the super surface unit 8₂0.001 lambda to 0.1 lambda, width W0.001 lambda to 0.1 lambda, lambda being the free space wavelength. Interdigital VO₂Width W of film₁0.0008 lambda to 0.08 lambda and a length L₃0.0005 lambda-0.05 lambda and 0.000001 lambda-0.001 lambda, and the specific length and width can be set according to the requirement of tuning frequency. Connecting interdigital VO₂Microstrip branch width W of film₂0.0005 lambda-0.05 lambda and length L₄Is 0.0001 lambda-0.01 lambda. Microstrip branch width W connecting radiation patches in horizontal dimension₃0.0005 lambda-0.05 lambda and length L₅Is 0.0005 lambda-0.05 lambda. The overall length L is 0.005 lambda to 0.5 lambda. Each set of rectangular patches is spaced 2 x L in the vertical dimension₁，L₁Is 0.0002 lambda to 0.02 lambda, lambda being the free space wavelength.

Further, as shown in fig. 6, the annular gap is a bone-type annular gap capable of coupling electromagnetic waves to the metal super-surface structure of the upper surface at two desired frequency points, wherein the width W of the outer side of the gap is₆Is 0.005 lambda-lambda and has a length L₈0.002 lambda-0.2 lambda, and the width W of the two side protruding parts₇Is 0.001 lambda to 0.1 lambda. Length L of convex parts at two sides of inner side of gap₉0.001 lambda-0.1 lambda, width W₈Is 0.001 lambda to 0.1 lambda.

Further, the width of the lower half part of the stepped rectangular waveguide 5 is 0.05 lambda-5 lambda, the length is 0.02 lambda-2 lambda, and the height is 0.2 lambda-2 lambda; the width of the upper half part is 0.05 lambda-5 lambda, the length is 0.01 lambda-1 lambda, and the height is 0.02 lambda-2 lambda, wherein lambda is the free space wavelength corresponding to the central frequency.

Further, the double-ridge structure 6 has a length of 0.01 λ - λ, a width of 0.01 λ - λ, and a height of 0.01 λ -2 λ, where λ is a free space wavelength corresponding to the center frequency.

The specific dimensions in this example are as follows:

the dielectric substrate 3 is made of sapphire (Al)₂O₃) Dielectric constant ε_r10, 0.5mm in thickness, about 0.5 lambda₀Wherein λ is₀Free space wavelength at center frequency 28 GHz; the medium substrate and the metal floor are rectangular, the width of the medium substrate is 14mm, and the length of the medium substrate is 7 mm.

Rectangular patch length L in the super-surface unit₂0.2mm and a width W of 0.5 mm. Width W of interdigital vanadium dioxide film₁Is 0.4mm, and has a length L₃Is 0.1mm, and the specific length and width can be set according to the requirement of tuning frequency. Microstrip branch width W for connecting interdigital vanadium dioxide film₂Is 0.1mm, and has a length L₄0.06mm and 200nm thick. The overall length L is 0.7 mm. The two rectangular patches in each super-surface unit are spaced 2 x L apart in the vertical dimension₁，L₁Is 0.1 mm.

In the horizontal dimension, adjacent super-surface units are connected by microstrip branches with the width W₃Is 0.1mm and has a length L₅Is 0.1 mm.

The integral metal super-surface structure 2 is composed of N × M super-surface units which are arranged periodically, wherein the periodic arrangement of the units means that the super-surface units are distributed according to horizontal rows and vertical columns, and the units in each horizontal row are aligned with the units in the next row.

The length W of the microstrip branch connected with the bias circuit and the metal super-surface structure₄，L₆，W₅1.1mm, 4.1mm and 2.5mm respectively, and the width is 0.1 mm. The radius R of the sector patch is 0.6mm, the angle is 90 degrees, the position of the sector patch can be adjusted according to the actual antenna processing requirement, but the antenna radiation patch is far as possible, and the influence on the radiation characteristic is avoided. Rectangular patch length and width L at DC feed₇Are all 0.5 mm.

The stepped rectangular waveguide 5 with the double-ridge structure has the lower half part of the waveguide with the size of WR28 standard waveguide, the length of 3.556mm, the width of 7.112mm and the height of 2.4 mm. The upper half of the stepped waveguide is 1.6mm long, 7.112mm wide and 6.4mm high. The double ridges in the waveguide are the same size, with a length of 0.65mm, a width of 0.5mm and a height of 2.8mm, located in the center of the rectangular waveguide, and attached to the edges of the annular slot.

When VO is shown in FIG. 5₂When the film is a conductor, the characteristic impedance Z of the super-surface₀At 28GHz, the real part reaches the maximum value, the imaginary part is 0, and resonance occurs; when VO is present₂When the film is an insulator, the characteristic impedance Z of the super-surface₀At 38GHz, the real part reaches a maximum and the imaginary part is 0, resonance occurs and the tuning ratio of the resonance frequency is about 1: 1.36. Shows that under the condition of low profile, the working frequency of the super-surface structure can be according to VO₂The conductivity of the film changes, and frequency tuning is realized.

Referring to fig. 6, the annular gap 9 is a bone-shaped annular gap with left and right symmetry, wherein the width W outside the gap₆Is 1.5mm, and has a length L₈0.6mm, and a width W of the protruding portions at both sides₇Is 0.35 mm. Length L of convex parts at two sides of inner side of gap₉Is 0.4mm, and has a width W₈Is 0.15 mm.

The current electric field distribution when the annular gap operates at the dual frequency is shown in fig. 7(a) and 7(b), in which the solid line arrows represent current and the dotted line arrows represent electric fields. When VO is present₂The film is a conductor, and the antenna works at 28 GHz: the current flows around the outer side of the gap, and the electric fields in the gap are vertical to excite the super-surface antenna; when VO is present₂The film is an insulator, and the antenna works at 38 GHz: in this case, the gap can be regarded as a boundary from the midpoint of the vertical dimension, and is divided into an upper gap and a lower gap, and the current flows around the outer side of each gap, and the upper gap and the lower gap are in the same phase and are both in the vertical direction.

VO-based data are shown in FIGS. 8(a) -8 (c)₂The frequency of the film can reconstruct the bandwidth, the gain and the directional diagram of the super-surface antenna in two frequency bands. FIG. 8(a) shows VO₂When the film is in a conductor state and an insulator state, the reflection coefficient and the gain curve of the antenna show that the working bandwidths with the reflection coefficient lower than-10 dB are respectively 26.8-30.7 GHz and 35.7-38.3 GHz, the relative bandwidths are about 13.5 percent and 7 percent, and the maximum gains are respectively 7.36dBi and 7.2 dBi; VO in FIG. 8(b) and VO in FIG. 8(c), respectively₂The directional diagram of the antenna when the film is in a conductor and insulator state shows that the super-surface antenna of the embodiment has good cross polarization and front-to-back ratio, and the directional diagram is quite symmetrical.

Specifically, the frequency-reconfigurable super-surface antenna based on the vanadium dioxide thin film of the embodiment is formed by adding VO₂The film is applied to a super-surface structure to analyze VO₂Designing a super-surface structure capable of realizing range frequency reconfiguration by the influence of the film on the unit resonant frequency before and after phase change; finally, the structure is used in a millimeter wave antenna, a bias circuit with the minimum influence on radiation characteristics is designed to provide direct current, the dual-frequency reconfigurable high-gain antenna is realized, and the structure is suitable for designing a 5G millimeter wave reconfigurable antenna.

Example 2

A communication device comprising the vanadium dioxide thin film based frequency reconfigurable super-surface antenna of embodiment 1.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.