A dual broadband linear polarization to circular polarization electromagnetic surface

Abstract

The present invention discloses a dual-wideband linear polarization-to-circular polarization electromagnetic surface, which relates to the field of wireless communication technology. The linear polarization-to-circular polarization electromagnetic surface includes three layers of dielectric substrates, and air gaps or foam layers are filled between adjacent dielectric substrates; forward patch metal units and backward patch metal units are periodically printed on the front and back surfaces of each layer of dielectric substrate; the forward patch metal unit is composed of four mirror-symmetrical fan-shaped patches and two rectangular strips, and the backward patch metal unit only includes a metal strip that runs through the entire unit. The present invention can achieve axial ratio bandwidth optimization in low-frequency bands and high-frequency bands by adjusting the unit size, dielectric substrate gap, and metal strip width, fan-shaped patch and coupling gap size. The dual-wideband linear polarization-to-circular polarization electromagnetic surface proposed by the present invention can cover the K / Ka satellite communication band, and has the characteristics of low insertion loss, and can be used for co-aperture dual circularly polarized high-throughput satellite communication applications.

Description

Technical Field

[0001] The invention relates to a broadband linear polarization-circular polarization electromagnetic surface (linear-circular polarization conversion surface) with dual-band low insertion loss, belonging to the technical field of wireless communication. Background Art

[0002] Circularly polarized waves have the advantages of overcoming Faraday rotation, polarization mismatch and multipath interference, and are often used in satellite communications and complex environment communications. Compared with traditional communication methods, satellite communications have unique advantages and application value such as high communication quality, wide coverage and all-weather. K / Ka band satellite communications require the use of orthogonal circular polarization modes in two wide working bands (i.e., the downlink and uplink bands are 17.7-20.2GHz and 27.5-31GHz, respectively), so it is required to be equipped with transmitting and receiving antenna arrays with orthogonal circular polarization rotation. In highly integrated satellite ground equipment, the receiving and transmitting antenna arrays need to be co-aperture integrated, and their circular polarization rotation needs to be controlled according to the channel used, which usually requires a complex feeding network. It is difficult to simultaneously achieve dual wideband, controllable rotation and co-aperture integration based on the conventional circularly polarized antenna array design, and the complexity of the feeding network will reduce the antenna efficiency.

[0003] A relatively simple method to generate circularly polarized waves is to use a linearly polarized antenna array in combination with a linear-circular polarization converter. By controlling the angle between the linear-circular polarization converter and the polarization of the incident wave, the polarization of the radiated wave of the linearly polarized antenna array can be effectively controlled to achieve the required circularly polarized emission. Therefore, this scheme is suitable for satellite communications that require circular polarization control. Compared with traditional circularly polarized antennas, the linearly polarized antenna in this scheme is not only simple to design, but can also be designed separately from the polarization converter. The circular polarization rotation direction can be achieved by rotating the polarization converter without the need for a complex feeding network.

[0004] Linear-circular polarization converters are mainly divided into two types: reflection type and transmission type. The reflection type linear-circular polarization converter usually has a complete metal ground structure, and can achieve complete reflection after polarization control of the incident wave. It usually has low reflection loss, but cannot achieve forward radiation and has the problem of feed source shielding. The transmission type linear-circular polarization converter needs to control the amplitude and phase of the transmitted wave at the same time, and has the problem of sensitivity to changes in the operating frequency, which makes it difficult to implement. Compared with the single-band linear-circular polarization converter, the linear-circular polarization converter with dual-band polarization twisting function has great advantages in two-way satellite communication systems. In the same aperture plane, it can realize the control of two orthogonal linear polarization incident waves into orthogonal circular polarization waves in two frequency bands for signal reception and transmission. How to achieve dual-wideband operation, low insertion loss, and suppress mutual interference between the two frequency bands is the key issue in the design of linear-circular polarization converters suitable for K / Ka band satellite communications. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a dual-wideband linear polarization to circular polarization electromagnetic surface for the needs of millimeter wave wireless communication and satellite communication, which has the advantages of dual frequency bands, wide axial ratio bandwidth (axial ratio <3dB), and low insertion loss, and at the same time has the advantages of simple processing, suitability for mass production, and convenience for planar integration.

[0006] Technical solution: The purpose of the present invention can be achieved through the following technical solution:

[0007] A dual-wideband linear polarization-to-circular polarization electromagnetic surface comprises an upper dielectric substrate, a middle dielectric substrate, and a lower dielectric substrate which are stacked in sequence from top to bottom; an air gap or a foam layer is filled between the upper dielectric substrate and the middle dielectric substrate, and an air gap or a foam layer is filled between the middle dielectric substrate and the lower dielectric substrate;

[0008] The metal layer on the upper surface of the upper dielectric substrate is periodically printed with a forward patch metal unit, and the forward patch metal unit contains four fan-shaped patches of the same shape and two rectangular strips of the same shape; the four fan-shaped patches are distributed in four quadrants and are mirror-symmetrical in the upper and lower directions and in the left and right directions, and the arc edges of the four fan-shaped patches are on the outside and located on the same circular contour line; the structure of each fan-shaped patch itself is asymmetric, and the contour is composed of a circular arc and two mutually perpendicular edges. There is a coupling gap in the middle of the fan-shaped patches in the left and right quadrants of the upper half plane, and there are the same coupling gaps in the middle of the two fan-shaped patches in the two quadrants of the lower half plane; a rectangular strip is arranged in the middle of the fan-shaped patches in the upper and lower quadrants of the left half plane, and the other rectangular strip is arranged in the middle of the two fan-shaped patches in the upper and lower quadrants of the right half plane; the midpoints of the outer narrow edges of the two rectangular strips are located on the circular contour where the outer arcs of the four asymmetric fan-shaped patches are located;

[0009] The lower surface metal layer of the upper dielectric substrate is periodically printed with a backward patch metal unit, and the backward patch metal unit only includes a metal strip running through the entire unit from top to bottom at the center; the metal strip covers the coupling gap in the middle of the forward patch metal unit and has a width greater than the gap width; the direction of the metal strip is orthogonal to the direction of the rectangular strip in the upper surface metal layer and has a width greater than the width of the rectangular strip;

[0010] The structures of the upper and lower metal layers of the middle dielectric substrate and the upper and lower metal layers of the lower dielectric substrate are the same as those of the upper and lower metal layers of the upper dielectric substrate.

[0011] Preferably, the axial ratio bandwidth of the electromagnetic surface at normal incidence and oblique incidence is optimized by scaling the size of the forward patch metal unit in the upper dielectric substrate, the middle dielectric substrate and / or the lower dielectric substrate.

[0012] Preferably, the axial ratio bandwidth of the electromagnetic surface in the low frequency band is optimized by adjusting the width of the metal strip of the backward patch metal unit; the axial ratio bandwidth of the electromagnetic surface in the high frequency band is optimized by adjusting the size of the four fan-shaped patches and the coupling gap size of the forward patch metal unit.

[0013] Preferably, the three-layer dielectric substrates are of the same size, the metal layers on the lower surfaces of the three-layer dielectric substrates are of the same size; the metal units on the upper surfaces of the middle-layer dielectric substrate and the lower-layer dielectric substrate are of the same size; the metal unit size on the upper surface of the upper-layer dielectric substrate is between 0.85 and 0.95 of the metal unit size on the upper surfaces of the middle-layer dielectric substrate and the lower-layer dielectric substrate.

[0014] Preferably, the upper surface metal layer of the upper dielectric substrate faces the incident and emitting directions of the circularly polarized wave, and the lower surface metal layer of the lower dielectric substrate faces the incident and emitting directions of the linearly polarized wave.

[0015] Preferably, the dielectric constant of the three-layer dielectric substrate is between 2 and 3.5, and the thickness h is in the range of 0.2 mm ≤ h ≤ 1 mm.

[0016] Preferably, the size of the forward patch metal unit of the metal layer on the upper surface of the three-layer dielectric substrate is the same as the array arrangement period value, and the range of the arrangement period p is 0.50λ 0 ≤p≤0.80λ 0 , where λ 0 It is the free space wavelength corresponding to the center frequency of the complete operating frequency band (dual band).

[0017] Preferably, the value range of the air gap thickness d is 0.15λ 0 ≤d≤0.35λ 0 .

[0018] Preferably, the electromagnetic surface operates in the K / Ka frequency band.

[0019] Preferably, through holes for positioning are provided around the electromagnetic surface.

[0020] Beneficial effects: The linear polarization-to-circular polarization electromagnetic surface proposed in the present invention has the characteristics of dual-band, low insertion loss and broadband. When the linear polarization-to-circular polarization electromagnetic surface is incident from the lower surface metal layer of the lower dielectric substrate by a 45° oblique linear polarization wave, the total incident field can be decomposed into two orthogonal linear polarization components. By adjusting the size and placement spacing of the fan-shaped patches in the horizontal and vertical directions, a transmission wave with a horizontal polarization component and a vertical polarization component of approximately equal amplitude and a phase difference of about 90° can be generated, that is, the polarization mode of the transmission wave is an approximately ideal circular polarization wave. The linear polarization-to-circular polarization electromagnetic surface proposed in the present invention also has the advantages of simple processing, suitable for mass production, and convenient planar integration, and is suitable for fifth-generation (5G) millimeter wave and satellite communication applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the stacked structure of an embodiment of the present invention.

[0022] Figure 2 The schematic diagram of the structure of the forward patch metal unit and the backward patch metal unit of each layer of dielectric substrate of the embodiment of the present invention. (a) and (b) correspond to the forward patch metal unit and the backward patch metal unit of the upper dielectric substrate respectively; (c) and (d) correspond to the forward patch metal unit and the backward patch metal unit of the middle dielectric substrate respectively; (e) and (f) correspond to the forward patch metal unit and the backward patch metal unit of the lower dielectric substrate respectively.

[0023] Figure 3 Schematic diagram of the structure of the forward patch and the backward patch array of the upper dielectric substrate of the embodiment of the present invention, wherein (a) corresponds to the forward patch array of the upper dielectric substrate; (b) corresponds to the backward patch array of the upper dielectric substrate.

[0024] Figure 4 Schematic diagram of the structure of the forward patch array and the backward patch array of the middle dielectric substrate of the embodiment of the present invention, wherein (a) corresponds to the forward patch array of the middle dielectric substrate; (b) corresponds to the backward patch array of the middle dielectric substrate.

[0025] Figure 5 Schematic diagram of the structure of the forward patch and the backward patch array of the lower dielectric substrate of the embodiment of the present invention, wherein (a) corresponds to the forward patch array of the lower dielectric substrate; (b) corresponds to the backward patch array of the lower dielectric substrate.

[0026] Figure 6 Schematic diagram of the foam layer structure between each dielectric substrate of the embodiment of the present invention. (a) corresponds to the foam layer between the upper dielectric substrate and the middle dielectric substrate; (b) corresponds to the foam layer between the middle dielectric substrate and the lower dielectric substrate.

[0027] Figure 7 Graph showing the low-frequency axial ratio test and simulation results of an embodiment of the present invention.

[0028] Figure 8 Graph showing high frequency axial ratio test and simulation results of an embodiment of the present invention.

[0029] Fig. 9 This is a diagram of the low-frequency band insertion loss test and simulation results of an embodiment of the present invention.

[0030] Fig.10 This is a diagram of the high-frequency band insertion loss test and simulation results of an embodiment of the present invention.

[0031] In the figure: 1: upper dielectric substrate; 2: middle dielectric substrate; 3: lower dielectric substrate; 4: first foam layer; 5: second foam layer; 6: upper surface metal layer of upper dielectric substrate; 7: lower surface metal layer of upper dielectric substrate; 8: upper surface metal layer of middle dielectric substrate; 9: lower surface metal layer of middle dielectric substrate; 10: upper surface metal layer of lower dielectric substrate; 11: lower surface metal layer of lower dielectric substrate; 1-1: first fan-shaped patch; 1-3: second fan-shaped patch; 1-4: third fan-shaped patch; 1-6: fourth Fan-shaped patch; 1-2: first rectangular strip; 1-5: second rectangular strip; 1-7: first metal strip; 2-1: fifth fan-shaped patch; 2-3: sixth fan-shaped patch; 2-4: seventh fan-shaped patch; 2-6: eighth fan-shaped patch; 2-2: third rectangular strip; 2-5: fourth rectangular strip; 2-7: second metal strip; 3-1: ninth fan-shaped patch; 3-3: tenth fan-shaped patch; 3-4: eleventh fan-shaped patch; 3-6: twelfth fan-shaped patch; 3-2: fifth rectangular strip; 3-5: sixth rectangular strip; 3-7: third metal strip; 6-1: first forward patch metal unit; 7-1 first backward patch metal unit; 8-1: second forward patch metal unit; 9-1: second backward patch metal unit; 10-1: third forward patch metal unit; 11-1 third backward patch metal unit. DETAILED DESCRIPTION

[0032] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0033] The embodiment of the present invention discloses a dual-wideband linear polarization-to-circular polarization electromagnetic surface, comprising an upper dielectric substrate, a middle dielectric substrate, and a lower dielectric substrate which are stacked in sequence from top to bottom; air gaps are filled between the upper dielectric substrate and the middle dielectric substrate, and between the middle dielectric substrate and the lower dielectric substrate, and the air gaps between the dielectric substrates can also be replaced by a foam layer with a dielectric constant lower than 1.3; a forward patch metal unit is periodically printed on the upper surface metal layer of the upper dielectric substrate, and the forward patch metal unit includes four fan-shaped patches of the same shape and two rectangular strips of the same shape; the four fan-shaped patches are distributed in four quadrants and present up-down and left-right mirror symmetry, and the arc edges of the four fan-shaped patches are on the outside and located on the same circular contour line; the structure of each fan-shaped patch itself is asymmetrical, and the contour is composed of a circular arc and two mutually perpendicular edges, there is a coupling gap in the middle of the fan-shaped patches in the left and right quadrants of the upper half plane, and there is a coupling gap in the middle of the fan-shaped patches in the two quadrants of the lower half plane. There is an identical coupling gap in the middle of two fan-shaped patches in the upper and lower quadrants of the left half plane; a rectangular strip is arranged in the middle of the fan-shaped patches in the upper and lower quadrants in the left half plane, and another rectangular strip is arranged in the middle of two fan-shaped patches in the upper and lower quadrants in the right half plane; the midpoints of the narrow sides of the two rectangular strips are located on the circular contour where the outer arcs of the four asymmetric fan-shaped patches are located; the lower surface metal layer of the upper dielectric substrate is periodically printed with backward patch metal units, and the backward patch metal unit only contains a metal strip running through the entire unit from top to bottom at the center; the metal strip covers the coupling gap in the middle of the forward patch metal unit and its width is greater than the gap width; the direction of the metal strip is orthogonal to the direction of the rectangular strip in the upper surface metal layer and its width is greater than the width of the rectangular strip; the structure of the upper surface metal layer and the lower surface metal layer of the middle dielectric substrate, as well as the structure of the upper surface metal layer and the lower surface metal layer of the lower dielectric substrate, are the same as the structure of the upper surface metal layer and the lower surface metal layer of the upper dielectric substrate.

[0034] In specific implementation, the axial ratio bandwidth of the polarization conversion electromagnetic surface at normal incidence and oblique incidence can be optimized by scaling the size of the forward patch metal unit in the upper dielectric substrate, the middle dielectric substrate, and the lower dielectric substrate. The axial ratio bandwidth of the electromagnetic surface in the low frequency band can be optimized by adjusting the width of the metal strip of the backward patch metal unit. The axial ratio band of the electromagnetic surface in the high frequency band can be optimized by adjusting the size of the four fan-shaped patches and the coupling gap of the forward patch metal unit.

[0035] For example, in some embodiments, three dielectric substrates of the same size are used, the metal layers on the bottom surfaces of the three dielectric substrates have the same size, the metal units on the top surfaces of the middle dielectric substrate and the bottom dielectric substrate have the same size, and the metal unit size on the top surface of the upper dielectric substrate is between 0.85 and 0.95 of the metal unit size on the top surface of the middle dielectric substrate and the bottom dielectric substrate, thereby achieving better axial ratio bandwidth performance.

[0036] The operating frequency band can be adjusted by adjusting the overall unit size and the air gap between the three-layer dielectric substrate.

[0037] In some embodiments, the dielectric constant of the three-layer dielectric substrate is between 2 and 3.5, and the thickness h is in the range of 0.2 mm ≤ h ≤ 1 mm. The size of the forward patch metal unit of the metal layer on the upper surface of the three-layer dielectric substrate is the same as the array arrangement period value, and the arrangement period p is in the range of 0.50λ 0 ≤p≤0.80λ 0 , the value range of the air gap thickness d is 0.15λ 0 ≤d≤0.35λ 0 .

[0038] For example, in the satellite communication frequency band of the K / Ka band, this embodiment designs a dual broadband linear polarization to circular polarization electromagnetic surface. Figure 1 As shown, the dual-wideband linear polarization to circular polarization electromagnetic surface includes an upper dielectric substrate 1, a middle dielectric substrate 2, and a lower dielectric substrate 3 which are stacked in sequence from top to bottom; in this embodiment, the thickness of the upper dielectric substrate 1, the middle dielectric substrate 2, and the lower dielectric substrate 3 is 0.254 mm, the relative dielectric constant is 2.94, and the loss tangent is 0.0012; the first foam layer 4 is filled between the upper dielectric substrate 1 and the middle dielectric substrate 2, and the second foam layer 5 is filled between the middle dielectric substrate 2 and the lower dielectric substrate 3; the size of the openings of the upper dielectric substrate 1, the middle dielectric substrate 2, and the lower dielectric substrate 3 is exactly the same as that of the first foam layer 4 and the second foam layer 5; the thickness of the first foam layer 4 and the second foam layer 5 is 2.5 mm, and the relative dielectric constant is 1.04.

[0039] like Figure 2As shown in (a), the upper surface metal layer 6 of the upper dielectric substrate is periodically printed with a first forward patch metal unit 6-1, and the first forward patch metal unit 6-1 includes four fan-shaped patches of the same shape: a first fan-shaped patch 1-1, a second fan-shaped patch 1-3, a third fan-shaped patch 1-4 and a fourth fan-shaped patch 1-6 and two horizontal rectangular strips of the same shape: a first rectangular strip 1-2 and a second rectangular strip 1-5; the first fan-shaped patch 1-1, the second fan-shaped patch 1-3, the third fan-shaped patch 1-4 and the fourth fan-shaped patch 1-6 are distributed in four quadrants in a counterclockwise order and are mirror-symmetrical up and down and left and right, and the arc edges of the four fan-shaped patches are on the outside, located On the same circular contour line; the first fan-shaped patch 1-1, the second fan-shaped patch 1-3, the third fan-shaped patch 1-4 and the fourth fan-shaped patch 1-6 have an asymmetric structure. There is a coupling narrow gap between the first fan-shaped patch 1-1 and the fourth fan-shaped patch 1-6 located in the left and right quadrants of the upper half plane, and there is the same coupling narrow gap between the second fan-shaped patch 1-3 and the third fan-shaped patch 1-4 located in the two quadrants of the lower half plane; the first rectangular strip 1-2 is arranged between the first fan-shaped patch 1-1 and the second fan-shaped patch 1-3 in the upper and lower quadrants of the left half plane, and the second rectangular strip 1-5 is arranged between the third fan-shaped patch 1-4 and the fourth fan-shaped patch 1-6 in the upper and lower quadrants of the right half plane. The midpoints of the outer narrow sides of the first rectangular strip 1-2 and the second rectangular strip 1-5 are located on the circular contours of the outer arcs of the four asymmetric first fan-shaped patches 1-1, the second fan-shaped patches 1-3, the third fan-shaped patches 1-4 and the fourth fan-shaped patches 1-6.

[0040] like Figure 2 As shown in (b), the lower surface metal layer 7 of the upper dielectric substrate is periodically printed with a first backward patch metal unit 7-1, which only contains a first metal strip 1-7 running through the entire unit from top to bottom at the center. The first metal strip 1-7 covers the coupling narrow gap between the two symmetrically distributed first fan-shaped patches 1-1 and the fourth fan-shaped patches 1-6 in the upper half plane of the first forward patch metal unit 6-1 and the coupling narrow gap between the two symmetrically distributed second fan-shaped patches 1-3 and the third fan-shaped patches 1-4 in the lower half plane and is slightly larger than the gap width; the direction of the first metal strip 1-7 is orthogonal to the direction of the first rectangular strip 1-2 and the second rectangular strip 1-5 in the upper surface metal layer; the width of the first metal strip 1-7 is slightly larger than the width of the first rectangular strip 1-2 and the second rectangular strip 1-5.

[0041] like Figure 2As shown in (c), the upper surface metal layer 8 of the middle dielectric substrate is periodically printed with a second forward patch metal unit 8-1, and the second forward patch metal unit 8-1 includes four fan-shaped patches of the same shape: the fifth fan-shaped patch 2-1, the sixth fan-shaped patch 2-3, the seventh fan-shaped patch 2-4 and the eighth fan-shaped patch 2-6 and two third rectangular strips 2-2 and the fourth rectangular strip 2-5 in the horizontal direction of the same shape; the fifth fan-shaped patch 2-1, the sixth fan-shaped patch 2-3, the seventh fan-shaped patch 2-4 and the eighth fan-shaped patch 2-6 are distributed in four quadrants in a counterclockwise order and are mirror-symmetrical up and down and left and right, and the arc edges of the four fan-shaped patches are on the outside and located on the same On the circular contour line; the fifth fan-shaped patch 2-1, the sixth fan-shaped patch 2-3, the seventh fan-shaped patch 2-4 and the eighth fan-shaped patch 2-6 have an asymmetric structure. There is a coupling narrow gap between the fifth fan-shaped patch 2-1 and the eighth fan-shaped patch 2-6 located in the left and right quadrants of the upper half plane, and there is the same coupling narrow gap between the sixth fan-shaped patch 2-3 and the seventh fan-shaped patch 2-4 located in the two quadrants of the lower half plane; the third rectangular strip 2-2 is arranged between the fifth fan-shaped patch 2-1 and the sixth fan-shaped patch 2-3 in the upper and lower quadrants of the left half plane, and the fourth rectangular strip 2-5 is arranged between the seventh fan-shaped patch 2-4 and the eighth fan-shaped patch 2-6 in the upper and lower quadrants of the right half plane. The midpoints of the outer narrow sides of the third rectangular strip 2-2 and the fourth rectangular strip 2-5 are located on the circular contour where the outer arcs of the four asymmetric fifth fan-shaped patches 2-1, the sixth fan-shaped patches 2-3, the seventh fan-shaped patches 2-4 and the eighth fan-shaped patches 2-6 are located.

[0042] like Figure 2 As shown in (d), the lower surface metal layer 9 of the middle dielectric substrate is periodically printed with a second backward patch metal unit 9-1, which only contains a second metal strip 2-7 running through the entire unit from top to bottom at the center. The second metal strip 2-7 covers the coupling narrow gap between the two symmetrically distributed fifth fan-shaped patches 2-1 and the eighth fan-shaped patches 2-6 in the upper half plane of the second forward patch metal unit 8-1 and the coupling narrow gap between the two symmetrically distributed sixth fan-shaped patches 2-3 and the seventh fan-shaped patches 2-4 in the lower half plane and is slightly larger than the gap width; the direction of the second metal strip 2-7 is orthogonal to the direction of the third rectangular strip 2-2 and the fourth rectangular strip 2-5 in the upper surface metal layer; the width of the second metal strip 2-7 is slightly larger than the width of the third rectangular strip 2-2 and the fourth rectangular strip 2-5.

[0043] like Figure 2As shown in (e), the upper surface metal layer 10 of the lower dielectric substrate is periodically printed with a third forward patch metal unit 10-1, and the third forward patch metal unit 10-1 includes four fan-shaped patches of the same shape: the ninth fan-shaped patch 3-1, the tenth fan-shaped patch 3-3, the eleventh fan-shaped patch 3-4 and the twelfth fan-shaped patch 3-6 and two horizontal rectangular strips of the same shape: the fifth rectangular strip 3-2 and the sixth rectangular strip 3-5; the ninth fan-shaped patch 3-1, the tenth fan-shaped patch 3-3, the eleventh fan-shaped patch 3-4 and the twelfth fan-shaped patch 3-6 are distributed in four quadrants in a counterclockwise order and are mirror-symmetrical up and down and left and right, and the arc edges of the four fan-shaped patches are on the outside, located On the same circular contour line; the ninth fan-shaped patch 3-1, the tenth fan-shaped patch 3-3, the eleventh fan-shaped patch 3-4 and the twelfth fan-shaped patch 3-6 have an asymmetric structure. There is a coupling narrow gap between the ninth fan-shaped patch 3-1 and the twelfth fan-shaped patch 3-6 located in the left and right quadrants of the upper half plane, and there is the same coupling narrow gap between the tenth fan-shaped patch 3-3 and the eleventh fan-shaped patch 3-4 located in the two quadrants of the lower half plane; the fifth rectangular strip 3-2 is arranged between the ninth fan-shaped patch 3-1 and the tenth fan-shaped patch 3-3 in the upper and lower quadrants of the left half plane, and the sixth rectangular strip 3-5 is arranged between the eleventh fan-shaped patch 3-4 and the twelfth fan-shaped patch 3-6 in the upper and lower quadrants of the right half plane. The midpoints of the outer narrow sides of the fifth rectangular strip 3-2 and the sixth rectangular strip 3-5 are located on the circular contour of the outer arcs of the four asymmetric ninth fan-shaped patches 3-1, the tenth fan-shaped patches 3-3, the eleventh fan-shaped patches 3-4 and the twelfth fan-shaped patches 3-6.

[0044] like Figure 2 As shown in (f), the third backward patch metal unit 11-1 is periodically printed in the lower surface metal layer 11 of the lower dielectric substrate, and the unit only contains a third metal strip 3-7 running through the entire unit from top to bottom at the center. The third metal strip 3-7 covers the coupling narrow gap between the two symmetrically distributed ninth fan-shaped patches 3-1 and the twelfth fan-shaped patches 3-6 in the upper half plane of the third forward patch metal unit 10-1 and the coupling narrow gap between the two symmetrically distributed tenth fan-shaped patches 3-3 and the eleventh fan-shaped patches 3-4 in the lower half plane and is slightly larger than the gap width; the direction of the third metal strip 3-7 is orthogonal to the direction of the fifth rectangular strip 3-2 and the sixth rectangular strip 3-5 in the upper surface metal layer; the width of the third metal strip 3-7 is slightly larger than the width of the fifth rectangular strip 3-2 and the sixth rectangular strip 3-5.

[0045] In this embodiment, the upper dielectric substrate 1, the middle dielectric substrate 2 and the lower dielectric substrate 3 are of the same size, and the lower surface metal layer 7 of the upper dielectric substrate, the lower surface metal layer 9 of the middle dielectric substrate and the lower surface metal layer 11 of the lower dielectric substrate are of the same size. The second forward patch metal unit 8-1 and the third forward patch metal unit 10-1 are of the same size; the size of the first forward patch metal unit 6-1 is nine tenths of the size of the second forward patch metal unit 8-1 and the third forward patch metal unit 10-1.

[0046] like Figure 3 As shown in (a) and (b), the upper surface metal layer 6 of the upper dielectric substrate includes 32×32 first forward patch metal units 6-1, and the lower surface metal layer 7 of the upper dielectric substrate includes 32×32 first backward patch metal units 7-1. The first forward patch metal units 6-1 and the first backward patch metal units 7-1 are arranged at a period of 7.8 mm. The size of the single-layer array structure is 249.6 mm×249.6 mm×0.254 mm. There are through holes around the array structure for positioning; the upper surface metal layer 6 of the upper dielectric substrate faces the emission direction of the circularly polarized wave.

[0047] like Figure 4 As shown in (a) and (b), the upper surface metal layer 8 of the middle dielectric substrate includes 32×32 second forward patch metal units 8-1, and the lower surface metal layer 9 of the middle dielectric substrate includes 32×32 second backward patch metal units 9-1. The second forward patch metal units 8-1 and the second backward patch metal units 9-1 are arranged at a period of 7.8mm. The size of the single-layer array structure is 249.6mm×249.6mm×0.254mm. There are through holes around the array structure for positioning.

[0048] like Figure 5 As shown in (a) and (b), the upper surface metal layer 10 of the lower dielectric substrate includes 32×32 third forward patch metal units 10-1, and the lower surface metal layer 11 of the lower dielectric substrate includes 32×32 third backward patch metal units 11-1. The third forward patch metal units 10-1 and the third backward patch metal units 11-1 are arranged at a period of 7.8 mm. The size of the single-layer array structure is 249.6 mm×249.6 mm×0.254 mm. There are through holes around the array structure for positioning; the lower surface metal layer 11 of the lower dielectric substrate faces the incident direction of the linearly polarized wave.

[0049] like Figure 6 As shown in (a) and (b), the thickness of the first foam layer 4 and the second foam layer 5 is 2.5 mm, the relative dielectric constant of the first foam layer 4 and the second foam layer 5 is 1.04, the loss tangent is 0.0017, and the size is 286 mm×286 mm×2.5 mm.

[0050] Figure 7 The measured and simulated results of the low-frequency axial ratio of the linear polarization-to-circular polarization electromagnetic surface are given. The 3dB axial ratio bandwidth of the designed linear polarization-to-circular polarization electromagnetic surface can cover 18GHz to 26GHz, with a relative bandwidth of 36.4%, covering the downlink frequency band of Ka-band satellite communication of 18.7-21.2GHz, and remains stable in the range of incident angle of 0-25°.

[0051] Figure 8 The measured and simulated results of the high-frequency axial ratio of the linear polarization-to-circular polarization electromagnetic surface are given. The 3dB axial ratio bandwidth of the designed linear polarization-to-circular polarization electromagnetic surface can cover 27GHz to 30.9GHz, with a relative bandwidth of 13.5%, almost covering the uplink frequency band of Ka-band satellite communication of 27.5-31GHz, and remains stable in the range of incident angle of 0-25°.

[0052] Fig. 9 The measured and simulated results of the low-frequency insertion loss of the linearly polarized to circularly polarized electromagnetic surface are given. The insertion loss of the designed linearly polarized to circularly polarized electromagnetic surface is less than 1.03dB in the range of 18 to 26GHz.

[0053] Fig.10 The measured and simulated results of the high-frequency insertion loss of the linearly polarized to circularly polarized electromagnetic surface are given. The insertion loss of the designed linearly polarized to circularly polarized electromagnetic surface is less than 1.66dB in the range of 27 to 31.5GHz.

[0054] Figures 1 to 10 It is shown that the linear polarization-to-circular polarization electromagnetic surface designed in the embodiment of the present invention has good wide-band characteristics, and the axial ratio and insertion loss within the band meet the design requirements, and is suitable for the needs of millimeter-wave wireless communications represented by low-orbit satellites and Ka-band satellite communication technologies.

[0055] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A dual broadband linear polarization to circular polarization electromagnetic surface, characterized in that: It comprises an upper dielectric substrate, a middle dielectric substrate and a lower dielectric substrate which are stacked in sequence from top to bottom; An air gap or a foam layer is filled between the upper dielectric substrate and the middle dielectric substrate, and an air gap or a foam layer is filled between the middle dielectric substrate and the lower dielectric substrate; The metal layer on the upper surface of the upper dielectric substrate is periodically printed with forward patch metal units, and the forward patch metal units include four sector-shaped patches of the same shape and two rectangular strips of the same shape; Four fan-shaped patches are distributed in four quadrants and present up-down and left-right mirror symmetry, and the arc edges of the four fan-shaped patches are on the outside and located on the same circular contour line; the structure of each fan-shaped patch itself is asymmetric, and the contour is composed of a circular arc and two mutually perpendicular edges. There is a coupling gap in the middle of the fan-shaped patches in the left and right quadrants of the upper half plane, and there is the same coupling gap in the middle of the two fan-shaped patches in the two quadrants of the lower half plane; a rectangular strip is arranged in the middle of the fan-shaped patches in the upper and lower quadrants of the left half plane, and another rectangular strip is arranged in the middle of the two fan-shaped patches in the upper and lower quadrants of the right half plane; the midpoints of the outer narrow edges of the two rectangular strips are located on the circular contour where the outer arcs of the four asymmetric fan-shaped patches are located; The lower surface metal layer of the upper dielectric substrate is periodically printed with a backward patch metal unit, and the backward patch metal unit only includes a metal strip running through the entire unit from top to bottom at the center; the metal strip covers the coupling gap in the middle of the forward patch metal unit and has a width greater than the gap width; the direction of the metal strip is orthogonal to the direction of the rectangular strip in the upper surface metal layer and has a width greater than the width of the rectangular strip; The structures of the upper and lower metal layers of the middle dielectric substrate and the upper and lower metal layers of the lower dielectric substrate are the same as those of the upper and lower metal layers of the upper dielectric substrate.

2. The dual broadband linear polarization to circular polarization electromagnetic surface according to claim 1, characterized in that: The axial ratio bandwidth of the electromagnetic surface at normal incidence and oblique incidence is optimized by scaling the size of the forward patch metal unit in the upper dielectric substrate, the middle dielectric substrate and / or the lower dielectric substrate.

3. The dual broadband linear polarization to circular polarization electromagnetic surface according to claim 1, characterized in that: The axial ratio bandwidth of the electromagnetic surface in the low frequency band is optimized by adjusting the width of the metal strip of the backward patch metal unit; the axial ratio bandwidth of the electromagnetic surface in the high frequency band is optimized by adjusting the size of the four fan-shaped patches and the coupling gap size of the forward patch metal unit.

4. The dual broadband linear polarization to circular polarization electromagnetic surface according to claim 1, characterized in that: The three-layer dielectric substrates have the same size, and the metal layers on the lower surfaces of the three-layer dielectric substrates have the same size; the metal units on the upper surfaces of the middle-layer dielectric substrate and the lower-layer dielectric substrate have the same size; The size of the metal unit on the upper surface of the upper dielectric substrate is between 0.85 and 0.95 of the size of the metal unit on the upper surface of the middle dielectric substrate and the lower dielectric substrate.

5. The dual broadband linear polarization to circular polarization electromagnetic surface according to claim 1, characterized in that: The upper surface metal layer of the upper dielectric substrate faces the incident and emitting directions of the circularly polarized wave, and the lower surface metal layer of the lower dielectric substrate faces the incident and emitting directions of the linearly polarized wave.

6. The dual broadband linear polarization to circular polarization electromagnetic surface according to claim 1, characterized in that: The dielectric constant of the three-layer dielectric substrate is between 2 and 3.5, and the thickness h ranges from 0.2 mm ≤ h ≤ 1 mm.

7. The dual broadband linear polarization to circular polarization electromagnetic surface according to claim 1, characterized in that: The size of the forward patch metal unit of the metal layer on the upper surface of the three-layer dielectric substrate is the same as the array arrangement period value, and the value range of the arrangement period p is 0.50λ0≤p≤0.80λ0, where λ0 is the free space wavelength corresponding to the center frequency point of the complete working frequency band.

8. The dual broadband linear polarization to circular polarization electromagnetic surface according to claim 1, characterized in that: The value range of the air gap thickness d is 0.15λ0≤d≤0.35λ0, where λ0 is the free space wavelength corresponding to the center frequency point of the complete working frequency band.

9. The dual broadband linear polarization to circular polarization electromagnetic surface according to claim 1, characterized in that: The electromagnetic surface operates in the K / Ka frequency band.

10. The dual broadband linear polarization to circular polarization electromagnetic surface according to claim 1, characterized in that: Through holes for positioning are arranged around the electromagnetic surface.

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