Waveguide based on gradient metamaterial structure

Abstract

The invention discloses a waveguide based on a tapered metamaterial structure, the waveguide comprises a metamaterial structure and a rectangular opening waveguide, the rectangular opening waveguide is a metal electric wall waveguide and comprises two wide edges and two long edges, the two wide edges are perpendicular to a first direction axis, the two long edges are perpendicular to a second direction axis, and the two long edges are perpendicular to the first direction axis. The through direction of the waveguide is a third direction axis, the electromagnetic waves are transmitted along the third direction axis, the first direction axis, the second direction axis and the third direction axis are perpendicular to one another, and the positive direction of the third direction axis is the through direction of the waveguide; the metamaterial structures are arranged on the sides, facing the interior of the waveguide, of the two wide edges of the waveguide, the thickness of the metamaterial structures changes from thin to thick in the positive direction of the third direction axis, and the metamaterial structures are used for reducing energy loss in the process that the two wide edges of the rectangular opening waveguide are converted from the electric wall state to the magnetic wall state; the electric field transmission direction in the waveguide is perpendicular to the magnetic field transmission direction and is perpendicular to the electromagnetic wave transmission direction, the electric field is transmitted along the second direction axis, and the magnetic field is transmitted along the first direction axis.

Description

Technical Field

[0001] The present invention relates to the field of antenna and microwave technology, and more specifically, to a waveguide based on a gradient metamaterial structure. Background Art

[0002] Waveguides are structures commonly used to transmit electromagnetic waves in the field of microwaves and antennas. Conventional rectangular waveguides are made of a hollow metal, which makes their boundaries electric walls. The main propagation mode of this waveguide is the TE10 mode, and the electric field in its cross section is sinusoidally distributed.

[0003] At present, with the rapid development of metamaterial structures, various metamaterial structures have been widely used in microwave technology design. Existing technology shows that the high impedance characteristics of certain metamaterial structures such as artificial magnetic conductors can change the electromagnetic wave transmission in traditional waveguide structures.

[0004] Since the addition of metamaterials brings about excessive energy loss and is structurally unfavorable for engineering implementation, it has not yet been found that metamaterial structures can be used to improve waveguide efficiency. Summary of the invention

[0005] The present invention provides a waveguide based on a gradient metamaterial structure to solve at least one of the problems existing in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a waveguide based on a gradient metamaterial structure, comprising a metamaterial structure and a rectangular opening waveguide, wherein:

[0008] The rectangular open waveguide is a metal electric wall waveguide, and the rectangular open waveguide includes two wide sides and two long sides, wherein the two wide sides are perpendicular to the first direction axis, the two long sides are perpendicular to the second direction axis, the penetration direction of the rectangular open waveguide is the third direction axis, and the electromagnetic wave is transmitted along the third direction axis, the first direction axis, the second direction axis and the third direction axis are perpendicular to each other, and the positive direction of the third direction axis is the penetration direction of the rectangular open waveguide;

[0009] The metamaterial structure is arranged on one side of the two wide sides of the rectangular open waveguide facing the inside of the waveguide, and the thickness of the metamaterial structure changes from thin to thick along the positive direction of the third axis, so as to reduce the energy loss in the process of converting the two wide sides of the rectangular open waveguide from the electric wall state to the magnetic wall state;

[0010] The electric field transmission direction inside the rectangular open waveguide is perpendicular to the magnetic field transmission direction, and both are perpendicular to the electromagnetic wave transmission direction, wherein the electric field transmission direction is transmitted along the second direction axis, and the magnetic field transmission direction is transmitted along the first direction axis.

[0011] Optionally, the rectangular open waveguide comprises an input feeding port and a radiation port, the input feeding port is arranged at an opening on a side away from the metamaterial structure along the third direction axis, and the radiation port is arranged on a side close to the metamaterial structure along the third direction axis;

[0012] The electromagnetic wave is transmitted from the input feeding port to the radiation port along a third axial direction.

[0013] Optionally, the metamaterial structure includes a dielectric plate and a metal patch.

[0014] The dielectric plates are respectively arranged on one side of the two wide sides of the rectangular open waveguide facing the inside of the waveguide, and the metal patch is attached to the side of the dielectric plate facing the inside of the waveguide. The metal patch is used to convert the propagation mode of the electromagnetic wave inside the waveguide.

[0015] Optionally, the thickness of the dielectric plate changes from thin to thick along the positive direction of the third directional axis, and the size of the metal patch changes from large to small along the positive direction of the third directional axis;

[0016] The thickness of the dielectric plate gradually increases from preset starting and ending positions to a preset cut-off position along the positive direction of the third axial axis, the preset starting position is a position of the dielectric plate close to a feeding port, and the preset cut-off position is a position of one tenth of the length of the long side of the waveguide.

[0017] Optionally, the dielectric plate is arranged on the wide side close to the radiation port of the waveguide, the dielectric plate is arranged opposite to each other along two wide sides of the waveguide, and the length of the dielectric plate is five wavelengths, which is the wavelength of the electromagnetic wave inside the waveguide.

[0018] Optionally, the metal patch is arranged in an array along the positive direction of the third direction axis, the metal patch is rectangular, includes a first side and a second side, the length of the first side along the second direction axis is less than a quarter wavelength, and the length of the second side along the third direction axis is less than or equal to the length of the first side.

[0019] Optionally, the thickness of the metal patch is a preset thickness.

[0020] Optionally, the electric field of the cross section of the waveguide at a wavelength away from the feeding port along the third direction axis is sinusoidally distributed;

[0021] The electric field of the cross section of the waveguide at a distance of three wavelengths from the feeding port along the third direction axis is quasi-uniformly distributed;

[0022] The electric field of the cross section of the waveguide at a distance of five wavelengths from the feeding port along the third direction axis is uniformly distributed.

[0023] Optionally, the material of the dielectric plate is polytetrafluoroethylene, and the material of the metal patch is a copper sheet.

[0024] Optionally, the electromagnetic waves in the waveguide include TEM waves.

[0025] The beneficial effects of the present invention are as follows:

[0026] The present invention provides a waveguide based on a gradient metamaterial structure. By designing a gradient metamaterial structure on two wide sides of a rectangular open waveguide facing the inside of the waveguide, a low-loss metamaterial structure is adopted without adding an external structure, so that a traditional electric wall waveguide is transformed into an electric wall and magnetic wall hybrid waveguide structure, and an electromagnetic wave propagation mode in the waveguide is transformed into a TEM wave, thereby reducing energy loss in the process of converting the two wide sides of the rectangular open waveguide from the electric wall state to the magnetic wall state, thereby improving the efficiency of the waveguide, and solving the problems of energy loss and complex structure to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0028] Figure 1 A schematic diagram of a waveguide based on a gradient metamaterial structure provided by the present invention is shown;

[0029] Figure 2 A schematic diagram showing the structure of a metamaterial structural unit in an embodiment of the present invention is shown;

[0030] FIG3( a ) is a schematic diagram showing the reflection phase of the metamaterial structure at 17 GHz with different dielectric plate thicknesses and different patch sizes;

[0031] FIG3( b ) is a schematic diagram showing the insertion loss of the metamaterial structure at 17 GHz with different dielectric plate thicknesses and different patch sizes;

[0032] Figure 4 A transmission loss comparison diagram of a waveguide based on a gradient metamaterial structure in the present embodiment and a waveguide with a metamaterial structure of fixed thickness within a designed frequency band is shown;

[0033] Figure 5 A schematic diagram showing the change of the electric field in the cross section of the waveguide based on the gradient metamaterial structure during the transmission process in this embodiment;

[0034] Figure 6 A schematic diagram showing a gain comparison between a waveguide based on a gradient metamaterial structure provided by this embodiment and a traditional metal waveguide is shown. DETAILED DESCRIPTION

[0035] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0036] The present invention provides a waveguide based on a gradient metamaterial structure, which transforms a traditional metal electric wall waveguide through a metamaterial structure with low loss and without increasing the external structure of the waveguide, thereby obtaining a high-efficiency waveguide with a metamaterial structure. The waveguide based on a gradient metamaterial structure provided by the present invention not only improves the gain and efficiency of the traditional waveguide, but also expands the overall functionality of the traditional waveguide.

[0037] The present invention provides a waveguide based on a gradient metamaterial structure, comprising a metamaterial structure and a rectangular opening waveguide, wherein the rectangular opening waveguide is a traditional metal electric wall waveguide, and the rectangular opening waveguide comprises two wide sides and two long sides. Figure 1 As shown, the length of the long side of the rectangular open waveguide is greater than the length of the wide side, the two wide sides are perpendicular to the first direction axis, the two long sides are perpendicular to the second direction axis, the electromagnetic wave is transmitted along the third direction axis, the first direction axis, the second direction axis and the third direction axis are perpendicular to each other, and the positive direction of the third direction axis is the through direction of the rectangular open waveguide; the rectangular open waveguide includes an input feeding port and a radiation port, the opening along the third direction axis close to the metamaterial structure is the radiation port, and the opening along the third direction axis away from the metamaterial structure is the input feeding port, and the electromagnetic wave is transmitted from the input feeding port to the radiation port along the third direction axis. The metamaterial structure is arranged on the side of the two wide sides of the rectangular open waveguide facing the inside of the waveguide, and the thickness of the metamaterial structure adopts a gradual design, which changes from thin to thick along the positive direction of the third direction axis, thereby reducing the energy loss in the process of converting the two wide sides of the rectangular open waveguide from the electric wall state to the magnetic wall state; the electric field transmission direction inside the rectangular open waveguide is perpendicular to the magnetic field transmission direction, and both are perpendicular to the electromagnetic wave transmission direction, wherein the electric field transmission direction is transmitted along the second direction axis, and the magnetic field transmission direction is transmitted along the first direction axis.

[0038] The metamaterial structure includes a dielectric plate and a metal patch. The dielectric plate is respectively arranged on two wide sides of the waveguide near the radiation port and the side facing the inside of the waveguide. The length is five wavelengths, and the wavelength is the wavelength of the electromagnetic wave in the waveguide. The thickness of the dielectric plate changes from thin to thick along the positive direction of the third axial axis. Specifically, the thickness of the dielectric plate gradually becomes thicker from a preset starting position to a preset end position along the positive direction of the third axial axis. The preset starting position is the position of the dielectric plate near the input feeding port, and the preset end position is one tenth of the length of the long side of the waveguide. The metal patches are respectively etched and attached to the side of the dielectric plate facing the inside of the waveguide. The metal patches are arranged in an array along the positive direction of the third axial axis, and the propagation mode of the electromagnetic wave in the waveguide is changed to TEM waves. The size of the metal patch changes from large to small along the positive direction of the third axial axis. The thickness of the metal patch is fixed. The metal patch is rectangular and includes a first side and a second side. The length of the first side is less than a quarter of the wavelength along the second axial axis, and the length of the second side is less than or equal to the length of the first side along the third axial axis.

[0039] The metamaterial structure with a gradient design can reduce the energy loss during the mode conversion of electromagnetic waves in a rectangular open waveguide, thereby reducing the transmission loss of the waveguide of the metamaterial structure. The material of the dielectric plate is Teflon, polystyrene foam or other low dielectric constant dielectric plates, and the material of the metal patch is copper sheet, which reduces the insertion loss of the metamaterial structure. The thickness of the dielectric plate changes from thin to thick along the positive direction of the third axis in a gradient manner. During the change of the thickness of the dielectric plate, the size of the metal patch is adjusted so that the metamaterial structure behaves as a magnetic wall. After the gradient part ends, the thickness of the dielectric plate and the size of the metal patch remain fixed, and both behave as magnetic walls with the gradient part.

[0040] The electromagnetic wave propagation mode in the rectangular open waveguide is TEM wave, which is transmitted along the third direction axis. The electric field in the rectangular open waveguide is transmitted along the second direction axis, and the magnetic field is transmitted along the first direction axis. The electric field transmission direction and the magnetic field transmission direction are perpendicular to each other and are both perpendicular to the electromagnetic wave transmission direction.

[0041] The cross-sectional electric field of the rectangular open waveguide changes gradually during the propagation process. When the rectangular open waveguide is one wavelength away from the feeding port along the third axis, its cross-sectional electric field distribution is a sinusoidal distribution; when it is three wavelengths away from the feeding port along the third axis, affected by the metamaterial structure, its cross-sectional electric field distribution gradually changes to a uniform distribution and presents a quasi-uniform distribution; when it is about five wavelengths away from the feeding port along the third axis, its cross-sectional electric field distribution has been converted to a uniform distribution, that is, the cross-sectional electric field at the radiation port of the rectangular open waveguide is uniformly distributed.

[0042] The present invention arranges metamaterial structures on two wide sides inside a rectangular open waveguide, so that the wide sides of the rectangular open waveguide appear in a magnetic wall state, changes the propagation mode of electromagnetic waves in the waveguide, and converts the electromagnetic waves in the waveguide from TE waves to TEM waves. Without enlarging the original electrical aperture outside the rectangular open waveguide, the present invention significantly improves the gain of the original standard rectangular open waveguide, thereby improving the efficiency of the waveguide section. The metamaterial structure adopted by the present invention has lower loss than other metamaterial structures, and is arranged on two wide sides of the waveguide facing the inside of the waveguide, thereby solving the problems of energy loss and structural disadvantages to implementation to a certain extent.

[0043] In a specific embodiment, Figure 1 As shown, a waveguide based on a gradient metamaterial structure provided by the present invention includes a rectangular open waveguide 1 and a metamaterial structure, wherein the metamaterial structure includes a dielectric plate 2 and a metal patch 3, wherein the first direction axis is the X-axis, the second direction axis is the Y-axis, and the third direction axis is the Z-axis. The rectangular open waveguide 1 is a pure metal electric wall waveguide, which works in the Ku-band. The two long sides of the waveguide are perpendicular to the Y-axis, and the two wide sides are perpendicular to the X-axis. The through direction of the rectangular open waveguide is the Z-axis direction, and the rectangular open waveguide 1 meets the national standard BJ140 size, with a long side length of 15.8 mm and a wide side length of 7.9 mm. The rear end of the rectangular open waveguide 1 is an input feeding port, and the front end is a radiation port. The electromagnetic waves in the waveguide are transmitted from the feeding port to the radiation port along the Z-axis. A gradient metamaterial structure is arranged on the two wide sides of the rectangular open waveguide 1 facing the inner side of the waveguide, and the thickness of the metamaterial structure changes from thin to thick along the positive direction of the Z axis, so that the wide sides of the rectangular open waveguide 1 appear in a magnetic wall state, so as to reduce the energy loss in the process of converting the two wide sides of the rectangular open waveguide from the electric wall state to the magnetic wall state.

[0044] The dielectric plate 2 is respectively placed on the side of the rectangular open waveguide 1 near the radiation port, with the two wide sides facing the inside of the waveguide. The thickness of the dielectric plate changes from thin to thick along the positive direction of the Z axis, and gradually becomes thicker from the preset start and end positions to the preset end position, wherein the preset end position is one tenth of the length of the long side of the waveguide; the dielectric plate 2 is arranged on the side of the inside of the waveguide near the radiation port, and the dielectric plate is arranged oppositely along the two wide sides of the waveguide, and its maximum length is five wavelengths. In this embodiment, the length of the dielectric plate 2 is set to five wavelengths. The metal patch 3 is respectively etched on the side of the dielectric plate 2 facing the inside of the waveguide through the PCB process, and the size of the metal patch 3 changes from large to small along the positive direction of the Z axis from the preset start and end positions to the preset end position. Multiple metal patches 3 are arranged in an array along the Z axis. In this embodiment, the metal patch 3 is a square, and its side length is less than a quarter of a wavelength. The thickness of the metal patch 3 can be 0.018 mm, and the thickness of the metal patch 3 is fixed.

[0045] In this embodiment, the long side of the waveguide based on the metamaterial structure is a metal structure, which is in an electric wall state, and the wide side is a metamaterial structure, which is in a magnetic wall state. This boundary condition makes the main mode of transmission in the waveguide TEM wave, and the transmission direction of the electric field and the transmission direction of the magnetic field are perpendicular to each other and are both perpendicular to the transmission direction of the electromagnetic wave, wherein the electric field is transmitted along the Y axis, the magnetic field is transmitted along the X axis, and the electromagnetic wave is transmitted along the Z axis.

[0046] like Figure 2 The schematic diagram of the structure of a metamaterial structural unit in this embodiment is shown. The material of the dielectric plate 2 can be polytetrafluoroethylene (Teflon), polystyrene foam or a dielectric plate 2 with a low dielectric constant. In this embodiment, the material of the dielectric plate 2 is preferably Teflon, and the thickness of the dielectric plate 2 is designed to change from 0.6mm to 1mm along the Z axis in a gradual manner. The metal patch 3 is a square copper sheet. When the thickness of the dielectric plate 2 changes, the size of the metal patch 3 is adjusted to make the reflection phase of the metamaterial unit structure zero, until the thickness of the dielectric plate reaches one tenth of the length of the long side of the waveguide, it is transformed into a dielectric plate of fixed thickness, and the size of the corresponding metal patch no longer changes.

[0047] FIG3(a) is a schematic diagram of the reflection phase of the metamaterial structure at 17 GHz frequency under different dielectric plate thicknesses and different patch sizes, wherein the five curves represent different dielectric plate 2 thicknesses, the horizontal axis represents the size of the metal patch 3, and the vertical axis represents the reflection phase. The thickness of the dielectric plate 2 is fixed to the size of the metal patch 3, wherein the thickness of the dielectric plate 2 is from 0.6 mm to 1 mm, and the size of the metal patch 3 is adjusted according to the thickness of the dielectric plate 2, and the corresponding relationship between the thickness of the dielectric plate 2 and the size of the metal patch 3 when the reflection phase of the metamaterial structure unit is zero is obtained. The corresponding relationship is: when the reflection phase is zero, the greater the thickness of the dielectric plate 2, the smaller the size of the metal patch 3. In this embodiment, the thickness of the dielectric plate 2 gradually increases from 0.6 mm to 1 mm, and is transformed into a dielectric plate of fixed thickness at 1 mm, and the size of the metal patch 3 is reduced from 3.77 mm to 3.48 mm and then transformed into a fixed size.

[0048] Figure 3(b) shows the insertion loss of the metamaterial structure at 17 GHz with different dielectric plate thicknesses and different patch sizes. The five curves represent different dielectric plate 2 thicknesses, the horizontal axis represents the size of the metal patch 3, and the vertical axis represents the insertion loss. m1 represents that when the dielectric plate 2 is 1 mm thick, the side length of the metal patch 3 is 3.4854 mm, and the corresponding insertion loss is 0.0341 dB; m2 represents that when the dielectric plate 2 is 0.9 mm thick, the side length of the metal patch 3 is 3.5651 mm, and the corresponding insertion loss is 0.0341 dB. The corresponding insertion loss is 0.0369dB; m3 means that when the thickness of the dielectric plate 2 is 0.8mm, the side length of the metal patch 3 is 3.6435mm, and the corresponding insertion loss is 0.0400dB; m4 means that when the thickness of the dielectric plate 2 is 0.7mm, the side length of the metal patch 3 is 3.7176mm, and the corresponding insertion loss is 0.0445dB; m5 means that when the thickness of the dielectric plate 2 is 0.6mm, the side length of the metal patch 3 is 3.7760mm, and the corresponding insertion loss is 0.0505dB. It can be seen that the insertion loss of the metamaterial structure unit is about 0.03dB to 0.05dB, which is a low loss state. And when the thickness of the dielectric plate 2 is 1mm and the size of the patch size 3 is about 3.48mm, the insertion loss of the metamaterial structure is the smallest.

[0049] The metamaterial structure is designed in a gradual manner, so that the thickness of the dielectric plate 2 of the metamaterial structure changes from 0.6 mm to 1 mm along the Z axis, and the size of the metal patch 3 changes accordingly from 3.77 mm to 3.48 mm along the Z axis. The thickness of the dielectric plate 2 gradually changes to 1 mm and then maintains the thickness until the radiation port, thereby keeping the reflection phase of the metamaterial structure at zero, so that the periodic surface composed of the metamaterial structure behaves as a high impedance surface with magnetic conductor characteristics.

[0050] Figure 4 The figure shows the transmission loss comparison of the waveguide based on the metamaterial structure in the embodiment within the design frequency band and the waveguide without gradient design. The four curves in the figure respectively represent the metamaterial structure with different thicknesses and the gradient metamaterial structure. The horizontal axis represents the frequency and the vertical axis represents the transmission loss. Figure 4 ,In the frequency band from 16.5GHz to 17.5GHz, the waveguide with a metamaterial structure using a gradient design has the lowest transmission loss, which is better than the waveguide with a metamaterial structure using a fixed thickness.

[0051] Figure 5A schematic diagram showing the change of the cross-sectional electric field of the waveguide based on the metamaterial structure during the transmission process in this embodiment is shown. The cross-sectional electric field of the waveguide during the propagation process gradually changes with the transmission process. At one wavelength away from the feeding port, its cross-sectional electric field distribution is a sinusoidal distribution; at three wavelengths away from the feeding port, affected by the metamaterial structure, its cross-sectional electric field distribution gradually transforms to a uniform distribution, but is still unstable; at the radiation port about five wavelengths away from the feeding port, its cross-sectional electric field distribution has been transformed into a quasi-uniform distribution that is approximately a uniform distribution.

[0052] Figure 6 A schematic diagram showing a gain comparison between the waveguide with a metamaterial structure provided by the present invention and the traditional metal waveguide at a mid-frequency point of 17 GHz is shown, wherein m6 is the normal gain value of the high-efficiency waveguide, and m7 is the normal gain value of the traditional metal waveguide. The gain of the waveguide based on the metamaterial structure in this embodiment is 6.6050 dB, and the gain of the traditional metal waveguide is 6.1995 dB, that is, the normal gain of the waveguide based on the metamaterial structure in this embodiment is improved by approximately 0.4 dB.

[0053] According to the calculation formula of aperture efficiency

[0054]

[0055] Among them, ε is the aperture efficiency, G0 is the actual gain of the antenna, G i is the ideal aperture gain, S is the aperture size, i.e. 124.82mm 2 , λ is the wavelength, and the ideal aperture gain G is calculated i It can be seen that the waveguide provided in this embodiment improves the aperture efficiency of the traditional metal waveguide from 88% to 94%.

[0056] The present invention transforms the wide side boundary in the rectangular open waveguide through a low-loss metamaterial structure without adding an external structure to the rectangular open waveguide, adopts a gradual metamaterial structure to make the wide side of the rectangular open waveguide appear in a magnetic wall state, changes the propagation mode of electromagnetic waves in the rectangular open waveguide, obtains a waveguide in which an electric wall and a magnetic wall coexist, and improves the overall gain and efficiency of the waveguide.

[0057] In the description of the present invention, it should be noted that the terms "upper", "lower", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0058] It should also be noted that, in the description of the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0059] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A waveguide based on a gradient metamaterial structure, characterized in that: It includes a metamaterial structure and a rectangular opening waveguide, wherein: The rectangular open waveguide is a metal electric wall waveguide, and the rectangular open waveguide includes two wide sides and two long sides, wherein the two wide sides are perpendicular to the first direction axis, the two long sides are perpendicular to the second direction axis, the penetration direction of the rectangular open waveguide is the third direction axis, and the electromagnetic wave is transmitted along the third direction axis, the first direction axis, the second direction axis and the third direction axis are perpendicular to each other, and the positive direction of the third direction axis is the penetration direction of the rectangular open waveguide; The metamaterial structure is arranged on one side of the two wide sides of the rectangular open waveguide facing the inside of the waveguide, and the thickness of the metamaterial structure changes from thin to thick along the positive direction of the third axis, so as to reduce the energy loss in the process of converting the two wide sides of the rectangular open waveguide from the electric wall state to the magnetic wall state; The electric field transmission direction inside the rectangular open waveguide is perpendicular to the magnetic field transmission direction, and both are perpendicular to the electromagnetic wave transmission direction, wherein the electric field transmission direction is transmitted along the second direction axis, and the magnetic field transmission direction is transmitted along the first direction axis.

2. The waveguide according to claim 1, characterized in that The rectangular open waveguide comprises an input feeding port and a radiation port, wherein the input feeding port is arranged on a side away from the metamaterial structure along the third direction axis, and the radiation port is arranged on a side close to the metamaterial structure along the third direction axis; The electromagnetic wave is transmitted from the input feeding port to the radiation port along a third axial direction.

3. The waveguide according to claim 1, characterized in that The metamaterial structure includes a dielectric plate and a metal patch. The dielectric plates are respectively arranged on one side of the two wide sides of the rectangular open waveguide facing the inside of the waveguide, and the metal patch is attached to the side of the dielectric plate facing the inside of the waveguide. The metal patch is used to convert the propagation mode of the electromagnetic wave inside the waveguide.

4. The waveguide according to claim 3, characterized in that The thickness of the dielectric plate changes from thin to thick along the positive direction of the third directional axis, and the size of the metal patch changes from large to small along the positive direction of the third directional axis; The thickness of the dielectric plate gradually increases from a preset starting position to a preset end position along the positive direction of the third axial axis, the preset starting position is a position of the dielectric plate close to a feeding port, and the preset end position is a position of one tenth of the length of the long side of the waveguide.

5. The waveguide according to claim 3, characterized in that The dielectric plate is arranged on the wide side close to the radiation port of the waveguide. The dielectric plate is arranged opposite to each other along the two wide sides of the waveguide. The length of the dielectric plate is five wavelengths, which is the wavelength of the electromagnetic wave inside the waveguide.

6. The waveguide according to claim 5, characterized in that The metal patch is arranged in an array along the positive direction of the third direction axis. The metal patch is rectangular and includes a first side and a second side. The length of the first side along the second direction axis is less than a quarter wavelength, and the length of the second side along the third direction axis is less than or equal to the length of the first side.

7. The waveguide according to claim 3, characterized in that The thickness of the metal patch is a preset thickness.

8. The waveguide according to claim 2, characterized in that The electric field of the cross section of the waveguide at a wavelength away from the feeding port along the third axis is sinusoidally distributed; The electric field of the cross section of the waveguide at a distance of three wavelengths from the feeding port along the third direction axis is quasi-uniformly distributed; The electric field of the cross section of the waveguide at a distance of five wavelengths from the feeding port along the third direction axis is uniformly distributed.

9. The waveguide according to claim 2, characterized in that The material of the dielectric plate is polytetrafluoroethylene, and the material of the metal patch is a copper sheet.

10. The waveguide according to claim 1, characterized in that The electromagnetic waves within the waveguide include TEM waves.

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