Dual-wideband linear-to-circular polarization conversion electromagnetic surface

Abstract

The present invention relates to the technical field of wireless communications. Disclosed is a dual-wideband linear-to-circular polarization conversion electromagnetic surface. The linear-to-circular polarization conversion electromagnetic surface comprises three dielectric substrates, wherein an air gap or a foam layer is provided between adjacent dielectric substrates. Front-side metallic patch units and back-side metallic patch units are cyclically printed on front and back surfaces of each dielectric substrate, wherein each front-side metallic patch unit is composed of four fan-shaped patches, which are in mirror symmetry, and two rectangular strips, and each back-side metallic patch unit only comprises a metallic strip that runs through the whole unit. By means of the present invention, the axial ratio bandwidths in a low band and a high band can be optimized by means of adjusting the sizes of units, gaps between dielectric substrates, the widths of metal strips, and the sizes of fan-shaped patches and the sizes of coupling gaps.

Description

A dual-wideband linear-polarized to circular-polarized electromagnetic surface Technical Field

[0001] This invention relates to a broadband linear-to-circular polarization electromagnetic surface (linear-to-circular polarization conversion surface) with low insertion loss in dual frequency bands, belonging to the field of wireless communication technology. Background Technology

[0002] Circularly polarized waves offer advantages such as overcoming Faraday rotation, polarization mismatch, and multipath interference, and are commonly used in satellite communications and communications in complex environments. Compared to traditional communication methods, satellite communications offer unique advantages and application value, including high communication quality, wide coverage, and all-weather capability. K / Ka band satellite communications require the use of orthogonal circular polarization modes in two wide operating bands (17.7-20.2 GHz downlink and 27.5-31 GHz uplink bands), thus necessitating the use of transmit and receive antenna arrays with orthogonal circular polarization rotation. In highly integrated satellite ground equipment, the transmit and receive antenna arrays need to be integrated with a common aperture, and their circular polarization rotation direction needs to be adjusted according to the channel used, typically requiring a complex feed network. Conventional circularly polarized antenna array designs struggle to simultaneously achieve dual wideband, controllable rotation direction, and common aperture integration, while the complexity of the feed network reduces antenna efficiency.

[0003] A relatively simple method for generating circularly polarized waves is to combine a linearly polarized antenna array with a linear-to-circular polarization converter. By controlling the angle between the linear-to-circular polarization converter and the polarization of the incident wave, the polarization of the radiated wave from the linearly polarized antenna array can be effectively modulated, achieving the desired circularly polarized output. Therefore, this scheme is suitable for satellite communications requiring circular polarization control. Compared to traditional circularly polarized antennas, this scheme not only simplifies the design of the linearly polarized antenna but also allows for separate design from the polarization converter. The circular polarization direction can be achieved by rotating the polarization converter, eliminating the need for a complex feed network.

[0004] Linear-circular polarization converters (LCPs) are mainly divided into two types: reflective and transmission types. Reflective LCPs typically have a complete metallic ground structure, achieving complete reflection after polarization modulation of the incident wave. They generally have low reflection loss but cannot achieve forward radiation, resulting in feed obstruction issues. Transmission LCPs require simultaneous control of the amplitude and phase of the transmitted wave, making them sensitive to changes in operating frequency and more difficult to implement. Compared to single-band LCPs, LCPs with dual-band polarization torsion capabilities offer significant advantages in two-way satellite communication systems. Within the same aperture plane, they can modulate two orthogonally linearly polarized incident waves into orthogonally rotating circularly polarized waves for signal reception and transmission in two frequency bands. Achieving dual-band wideband operation, low insertion loss, and suppression of mutual interference between the two bands are key challenges in designing LCPs suitable for K / Ka band satellite communication. Summary of the Invention

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

[0006] Technical solution: The objective of this invention can be achieved through the following technical solution: A dual-bandwidth linear polarization to circular polarization electromagnetic surface, comprising an upper dielectric substrate, a middle dielectric substrate, and a lower dielectric substrate stacked sequentially from top to bottom; an air gap or foam layer is filled between the upper dielectric substrate and the middle dielectric substrate, and an air gap or foam layer is filled between the middle dielectric substrate and the lower dielectric substrate; The upper surface metal layer of the upper dielectric substrate is periodically printed with forward patch metal units. Each forward patch metal unit contains four identical fan-shaped patches and two identical rectangular strips. The four fan-shaped patches are distributed in four quadrants and are mirror-symmetrical vertically and horizontally. The arc edges of the four fan-shaped patches are on the outer side and located on the same circular outline. Each fan-shaped patch has an asymmetrical structure, with its outline consisting of an arc and two mutually perpendicular edges. There is a coupling gap between the fan-shaped patches in the upper half-plane and the two fan-shaped patches in the lower half-plane. A rectangular strip is arranged between the fan-shaped patches in the upper and lower quadrants of the left half-plane, and another rectangular strip is arranged between the two fan-shaped patches in the upper and lower quadrants of the right half-plane. The midpoints of the narrow outer edges of the two rectangular strips are located on the circular outline of the outer arcs of the four asymmetrical fan-shaped patches. The lower surface metal layer of the upper dielectric substrate is periodically printed with backward patch metal units, each backward patch metal unit containing only a metal strip running vertically through the entire unit at its 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 structures of the upper and lower surface metal layers of the middle dielectric substrate, and the upper and lower surface metal layers of the lower dielectric substrate, are the same as the structures of the upper and lower surface metal layers of the upper dielectric substrate.

[0007] Preferably, the axial bandwidth of the electromagnetic surface under normal and oblique incidence is optimized by scaling the size of the forward patch metal units in the upper dielectric substrate, middle dielectric substrate and / or lower dielectric substrate.

[0008] Preferably, the axial ratio bandwidth of the low-frequency band of the electromagnetic surface is optimized by adjusting the width of the metal strip of the backward patch metal unit; the axial ratio bandwidth of the high-frequency band of the electromagnetic surface is optimized by adjusting the size of the four fan-shaped patches and the coupling gap of the forward patch metal unit.

[0009] Preferably, the three dielectric substrates are of the same size, and the lower surface metal layer of the three dielectric substrates is of the same size; the upper surface metal unit of the middle dielectric substrate and the lower dielectric substrate is of the same size; the upper surface metal unit of the upper dielectric substrate is between 0.85 and 0.95 times the upper surface metal unit of the middle dielectric substrate and the lower dielectric substrate.

[0010] Preferably, the upper surface metal layer of the upper dielectric substrate faces the incident and exit directions of the circularly polarized wave, and the lower surface metal layer of the lower dielectric substrate faces the incident and exit directions of the linearly polarized wave.

[0011] Preferably, the dielectric constant of the three-layer dielectric substrate is between 2 and 3.5, and the thickness h ranges from 0.2 mm to h to 1 mm.

[0012] 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 0.50λ0≤p≤0.80λ0, where λ0 is the free space wavelength corresponding to the center frequency of the complete working frequency band (dual frequency band).

[0013] Preferably, the air gap thickness d is in the range of 0.15λ0≤d≤0.35λ0.

[0014] Preferably, the electromagnetic surface operates in the K / Ka frequency band.

[0015] Preferably, the electromagnetic surface is provided with through holes around its perimeter for positioning.

[0016] Beneficial Effects: The linear-polarized to circular-polarized electromagnetic surface proposed in this invention possesses dual-band, low insertion loss, and wide bandwidth characteristics. When a linearly polarized wave at a 45° angle is incident on the lower surface metal layer of the underlying dielectric substrate, the total incident field can be decomposed into two orthogonal linearly polarized components. By adjusting the size and spacing of the fan-shaped patches in the horizontal and vertical directions, transmitted waves with approximately equal amplitudes and a phase difference of about 90° between the horizontal and vertical polarized components can be generated; that is, the polarization mode of the transmitted wave is approximately ideal circularly polarized. The linear-polarized to circular-polarized electromagnetic surface proposed in this invention also has the advantages of simple processing, suitability for mass production, and ease of planar integration, making it suitable for fifth-generation (5G) millimeter-wave and satellite communication applications. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the stacked structure according to an embodiment of the present invention.

[0018] Figure 2 is a schematic diagram of the front-mount metal unit and the back-mount metal unit structure of each layer of dielectric substrate according to an embodiment of the present invention. (a) and (b) correspond to the front-mount metal unit and the back-mount metal unit of the upper dielectric substrate, respectively; (c) and (d) correspond to the front-mount metal unit and the back-mount metal unit of the middle dielectric substrate, respectively; and (e) and (f) correspond to the front-mount metal unit and the back-mount metal unit of the lower dielectric substrate, respectively.

[0019] Figure 3 is a schematic diagram of the front and back patch array structures of the upper dielectric substrate according to an embodiment of the present invention. Wherein (a) corresponds to the front patch array of the upper dielectric substrate; (b) corresponds to the back patch array of the upper dielectric substrate.

[0020] Figure 4 is a schematic diagram of the front and back patch array structures of the intermediate dielectric substrate according to an embodiment of the present invention. Wherein (a) corresponds to the front patch array of the intermediate dielectric substrate; (b) corresponds to the back patch array of the intermediate dielectric substrate.

[0021] Figure 5 is a schematic diagram of the front and rear patch array structures of the lower dielectric substrate according to an embodiment of the present invention. Wherein (a) corresponds to the front patch array of the lower dielectric substrate; (b) corresponds to the rear patch array of the lower dielectric substrate.

[0022] Figure 6 is a schematic diagram of the foam layer structure between the dielectric substrates of each layer in an embodiment of the present invention. Wherein (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.

[0023] Figure 7 shows the test and simulation results of the low-frequency axial ratio in an embodiment of the present invention.

[0024] Figure 8 shows the test and simulation results of the high-frequency axial ratio in an embodiment of the present invention.

[0025] Figure 9 shows the test and simulation results of low-frequency insertion loss in an embodiment of the present invention.

[0026] Figure 10 shows the high-frequency insertion loss test and simulation results of an embodiment of the present invention.

[0027] 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 the upper dielectric substrate; 7: Lower surface metal layer of the upper dielectric substrate; 8: Upper surface metal layer of the middle dielectric substrate; 9: Lower surface metal layer of the middle dielectric substrate; 10: Upper surface metal layer of the lower dielectric substrate; 11: Lower surface metal layer of the lower dielectric substrate; 1-1: First sector patch; 1-3: Second sector patch; 1-4: Third sector patch; 1-6: Fourth sector patch; 1-2: First rectangular strip; 1-5: Second rectangular strip; 1-7: First metal strip; 2-1: Fifth sector patch; 2 -3: Sixth sector patch; 2-4: Seventh sector patch; 2-6: Eighth sector patch; 2-2: Third rectangular strip; 2-5: Fourth rectangular strip; 2-7: Second metal strip; 3-1: Ninth sector patch; 3-3: Tenth sector patch; 3-4: Eleventh sector patch; 3-6: Twelfth sector 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 Implementation

[0028] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0029] This invention discloses a dual-wideband linear-polarized to circular-polarized electromagnetic surface, comprising an upper dielectric substrate, a middle dielectric substrate, and a lower dielectric substrate stacked sequentially from top to bottom. Air gaps are filled between the upper and middle dielectric substrates, and between the middle and lower dielectric substrates. These air gaps can also be replaced by a foam layer with a dielectric constant lower than 1.3. The upper surface metal layer of the upper dielectric substrate is periodically printed with forward patch metal units, each containing four identical fan-shaped patches and two identical rectangular strips. The four fan-shaped patches are distributed in four quadrants and exhibit vertical and horizontal mirror symmetry, with their arc edges on the outer side, located on the same circular outline. Each fan-shaped patch has an asymmetrical structure, its outline consisting of an arc and two mutually perpendicular edges. The fan-shaped patches in the upper half-plane have coupling gaps in the middle of the left and right quadrants, while those in the lower half-plane have coupling gaps in the middle of the left and right quadrants. Two sector patches in each quadrant have the same coupling gap between them; a rectangular strip is arranged between the sector patches in the upper and lower quadrants of the left half-plane, and another rectangular strip is arranged between the two sector patches in the upper and lower quadrants of the right half-plane; the midpoint of the outer narrow side of the two rectangular strips is located on the circular outline of the outer arc of the four asymmetrical sector patches; the lower surface metal layer of the upper dielectric substrate is periodically printed with backward patch metal units, and the backward patch metal unit contains only a metal strip running vertically through the entire unit at its 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 and lower surface metal layers of the middle dielectric substrate, and the structure of the upper and lower surface metal layers of the lower dielectric substrate are the same as the structure of the upper and lower surface metal layers of the upper dielectric substrate.

[0030] In practical implementation, the axial ratio bandwidth of the polarization-conversion electromagnetic surface under normal and oblique incidence conditions can be optimized by scaling the size of the forward-mounted metal units in the upper, middle, and lower dielectric substrates. The axial ratio bandwidth of the electromagnetic surface in the low-frequency band can be optimized by adjusting the width of the metal strips in the backward-mounted metal units. The axial ratio bandwidth 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 size of the forward-mounted metal units.

[0031] For example, in some embodiments, three dielectric substrates of the same size are used, with the lower surface metal layer of the three dielectric substrates having the same size, the upper surface metal unit of the middle dielectric substrate and the lower dielectric substrate having the same size, and the upper surface metal unit of the upper dielectric substrate being between 0.85 and 0.95 times the size of the upper surface metal unit of the middle dielectric substrate and the lower dielectric substrate, which can achieve better axial ratio bandwidth performance.

[0032] Adjusting the overall unit size and the air gap between the three dielectric substrates can adjust the operating frequency range.

[0033] In some embodiments, 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. The size of the forward patch metal unit of the upper surface metal layer of the three-layer dielectric substrate is the same as the array arrangement period value, the arrangement period p ranges from 0.50λ0 ≤ p ≤ 0.80λ0, and the air gap thickness d ranges from 0.15λ0 ≤ d ≤ 0.35λ0.

[0034] For example, in the K / Ka band satellite communication frequency band, this embodiment designs a dual-wideband linear-polarized to circular-polarized electromagnetic surface. As shown in Figure 1, the dual-wideband linear-polarized to circular-polarized electromagnetic surface includes an upper dielectric substrate 1, a middle dielectric substrate 2, and a lower dielectric substrate 3 stacked sequentially from top to bottom. In this embodiment, the upper dielectric substrate 1, the middle dielectric substrate 2, and the lower dielectric substrate 3 have a thickness of 0.254 mm, a relative permittivity of 2.94, and a loss tangent of 0.0012. A first foam layer 4 is filled between the upper dielectric substrate 1 and the middle dielectric substrate 2, and a second foam layer 5 is filled between the middle dielectric substrate 2 and the lower dielectric substrate 3. The aperture sizes of the upper dielectric substrate 1, the middle dielectric substrate 2, and the lower dielectric substrate 3 are exactly the same as those 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 permittivity is 1.04.

[0035] As shown in Figure 2(a), the upper surface metal layer 6 of the upper dielectric substrate is periodically printed with first forward patch metal units 6-1. Each first forward patch metal unit 6-1 contains four identical sector patches: first sector patch 1-1, second sector patch 1-3, third sector patch 1-4, and fourth sector patch 1-6, and two identical horizontal rectangular strips: first rectangular strip 1-2 and second rectangular strip 1-5. The first sector patches 1-1, second sector patches 1-3, third sector patches 1-4, and fourth sector patches 1-6 are distributed counterclockwise in the four quadrants and exhibit vertical and horizontal mirror symmetry, with the arc edges of the four sector patches on the outer side. On the same circular outline; the first sector patch 1-1, the second sector patch 1-3, the third sector patch 1-4 and the fourth sector patch 1-6 have asymmetrical structures. The first sector patch 1-1 and the fourth sector patch 1-6 located in the left and right quadrants of the upper half plane have a coupling narrow gap between them, and the second sector patch 1-3 and the third sector patch 1-4 located in the two quadrants of the lower half plane have the same coupling narrow gap between them; the first rectangular strip 1-2 is arranged between the first sector patch 1-1 and the second sector 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 sector patch 1-4 and the fourth sector 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 outline of the outer arcs of the four asymmetrical sector patches 1-1, 1-3, 1-4 and 1-6.

[0036] As shown in Figure 2(b), a first backward patch metal unit 7-1 is periodically printed in the lower surface metal layer 7 of the upper dielectric substrate. This unit contains only a first metal strip 1-7 running vertically through the entire unit at its center. The first metal strip 1-7 covers the coupling narrow gap between the two symmetrically distributed first sector patches 1-1 and fourth sector 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 sector patches 1-3 and third sector patches 1-4 in the lower half-plane, and is slightly larger than the gap width. The orientation of the first metal strip 1-7 is orthogonal to the orientation 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.

[0037] As shown in Figure 2(c), the upper surface metal layer 8 of the intermediate dielectric substrate is periodically printed with second forward patch metal units 8-1. Each second forward patch metal unit 8-1 contains four identical sector patches: a fifth sector patch 2-1, a sixth sector patch 2-3, a seventh sector patch 2-4, and an eighth sector patch 2-6, and two identical horizontally oriented third rectangular strips 2-2 and fourth rectangular strips 2-5. The fifth sector patch 2-1, the sixth sector patch 2-3, the seventh sector patch 2-4, and the eighth sector patch 2-6 are distributed counterclockwise in the four quadrants and exhibit vertical and horizontal mirror symmetry. Furthermore, the arc edges of the four sector patches are on the outer side, located in the same... On a circular outline; the fifth sector patch 2-1, the sixth sector patch 2-3, the seventh sector patch 2-4, and the eighth sector patch 2-6 have asymmetrical structures. The fifth sector patch 2-1 and the eighth sector patch 2-6, located in the left and right quadrants of the upper half-plane, have a coupling narrow gap between them, and the sixth sector patch 2-3 and the seventh sector patch 2-4, located in the two quadrants of the lower half-plane, have the same coupling narrow gap between them; the third rectangular strip 2-2 is arranged between the fifth sector patch 2-1 and the sixth sector 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 sector patch 2-4 and the eighth sector 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 outline of the outer arcs of the four asymmetrical sector patches 2-1, 2-3, 2-4, and 2-6.

[0038] As shown in Figure 2(d), the lower surface metal layer 9 of the intermediate dielectric substrate is periodically printed with second backward patch metal units 9-1. Each unit contains only a second metal strip 2-7 running vertically through the entire unit at its center. The second metal strip 2-7 covers the coupling narrow gap between the two symmetrically distributed fifth sector patches 2-1 and eighth sector 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 sector patches 2-3 and seventh sector patches 2-4 in the lower half-plane, and is slightly larger than the gap width. The orientation of the second metal strip 2-7 is orthogonal to the orientation of the third rectangular strip 2-2 and 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 fourth rectangular strip 2-5.

[0039] As shown in Figure 2(e), the upper surface metal layer 10 of the lower dielectric substrate is periodically printed with third forward patch metal units 10-1. The third forward patch metal unit 10-1 contains 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 rectangular strips of the same shape in the horizontal direction: 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 a counterclockwise order in the four quadrants and are mirror-symmetrical vertically and horizontally, with the arc edges of the four fan-shaped patches on the outer side. Located on the same circular outline; the ninth sector patch 3-1, the tenth sector patch 3-3, the eleventh sector patch 3-4, and the twelfth sector patch 3-6 have asymmetrical structures. The ninth sector patch 3-1 and the twelfth sector patch 3-6 located in the left and right quadrants of the upper half-plane have a coupling narrow gap between them, and the tenth sector patch 3-3 and the eleventh sector patch 3-4 located in the two quadrants of the lower half-plane have the same coupling narrow gap between them; the fifth rectangular strip 3-2 is arranged between the ninth sector patch 3-1 and the tenth sector 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 sector patch 3-4 and the twelfth sector 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 outline of the outer arcs of the four asymmetrical sector patches 3-1, 3-3, 3-4 and 3-6.

[0040] As shown in Figure 2(f), a third backward patch metal unit 11-1 is periodically printed in the lower surface metal layer 11 of the lower dielectric substrate. This unit contains only a third metal strip 3-7 running vertically through the entire unit at its center. The third metal strip 3-7 covers the coupling narrow gap between the two symmetrically distributed ninth sector patches 3-1 and twelfth sector 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 sector patches 3-3 and eleventh sector 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 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 sixth rectangular strip 3-5.

[0041] In this embodiment, the upper dielectric substrate 1, the middle dielectric substrate 2, and the lower dielectric substrate 3 are of the same size. 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.

[0042] As shown in Figures 3(a) and (b), the upper surface metal layer 6 of the upper dielectric substrate contains 32×32 first forward patch metal units 6-1, and the lower surface metal layer 7 of the upper dielectric substrate contains 32×32 first backward patch metal units 7-1. The arrangement period of the first forward patch metal units 6-1 and the first backward patch metal units 7-1 is 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 circular polarization emission.

[0043] As shown in Figures 4(a) and (b), the upper surface metal layer 8 of the middle dielectric substrate contains 32×32 second forward patch metal units 8-1, and the lower surface metal layer 9 of the middle dielectric substrate contains 32×32 second backward patch metal units 9-1. The arrangement period of the second forward patch metal units 8-1 and the second backward patch metal units 9-1 is 7.8 mm. The dimensions of the single-layer array structure are 249.6 mm × 249.6 mm × 0.254 mm. The array structure has through holes around its perimeter for positioning.

[0044] As shown in Figures 5(a) and (b), the upper surface metal layer 10 of the lower dielectric substrate contains 32×32 third forward patch metal units 10-1, and the lower surface metal layer 11 of the lower dielectric substrate contains 32×32 third backward patch metal units 11-1. The arrangement period of the third forward patch metal units 10-1 and the third backward patch metal units 11-1 is 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 linearly polarized incident light.

[0045] As shown in Figures 6(a) and (b), the thickness of the first foam layer 4 and the second foam layer 5 is 2.5 mm, the relative permittivity 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.

[0046] Figure 7 shows the measured and simulated results of the low-frequency axial ratio of the linear-to-circular polarization electromagnetic surface. The designed linear-to-circular polarization electromagnetic surface has a 3dB axial ratio bandwidth that can cover 18GHz to 26GHz, with a relative bandwidth of 36.4%, covering the downlink frequency band of Ka-band satellite communication from 18.7 to 21.2GHz, and remains stable within the incident angle range of 0-25°.

[0047] Figure 8 shows the measured and simulated results of the high-frequency axial ratio of the linear-to-circular polarization electromagnetic surface. The designed linear-to-circular polarization electromagnetic surface has a 3dB axial ratio bandwidth that can cover 27GHz to 30.9GHz, with a relative bandwidth of 13.5%, which almost covers the uplink frequency band of Ka-band satellite communication, 27.5-31GHz, and remains stable within the incident angle range of 0-25°.

[0048] Figure 9 shows the measured and simulation results of the insertion loss of the linear-to-circular polarization electromagnetic surface in the low-frequency range. The designed linear-to-circular polarization electromagnetic surface has an insertion loss of less than 1.03 dB in the range of 18 to 26 GHz.

[0049] Figure 10 shows the measured and simulation results of the high-frequency insertion loss of the linear-to-circular polarization electromagnetic surface. The designed linear-to-circular polarization electromagnetic surface has an insertion loss of less than 1.66 dB in the range of 27 to 31.5 GHz.

[0050] Figures 1 to 10 show that the linearly polarized to circularly polarized electromagnetic surface designed in the embodiments of the present invention has good broadband characteristics, and the in-band axial ratio and insertion loss meet the design requirements, making it suitable for the needs of millimeter-wave wireless communication represented by low-Earth orbit satellites and Ka-band satellite communication technologies.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A dual-wideband linear-polarized to circular-polarized electromagnetic surface, characterized in that, It includes an upper dielectric substrate, a middle dielectric substrate, and a lower dielectric substrate stacked sequentially from top to bottom; An air gap or foam layer is filled between the upper dielectric substrate and the middle dielectric substrate, and an air gap or foam layer is filled between the middle dielectric substrate and the lower dielectric substrate. The upper surface metal layer of the upper dielectric substrate is periodically printed with forward patch metal units, each of which contains four identical fan-shaped patches and two identical rectangular strips. Four sector patches are distributed in four quadrants and are mirror-symmetrical vertically and horizontally. The arc edges of the four sector patches are on the outside and lie on the same circular outline. Each sector patch has an asymmetrical structure, with its outline consisting of a circular arc and two mutually perpendicular edges. There is a coupling gap between the sector patches in the upper half-plane and the two sector patches in the lower half-plane. There is the same coupling gap between the two sector patches in the lower half-plane and the two sector patches in the upper and lower quadrants. A rectangular strip is arranged between the sector patches in the upper and lower quadrants of the left half-plane, and another rectangular strip is arranged between the two sector patches in the upper and lower quadrants of the right half-plane. The midpoints of the narrow outer edges of the two rectangular strips are located on the circular outline of the outer arcs of the four asymmetrical sector patches. The lower surface metal layer of the upper dielectric substrate is periodically printed with backward patch metal units. Each backward patch metal unit contains only one metal strip running vertically through the entire unit at its 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 structures of the upper and lower surface metal layers of the middle dielectric substrate, and the upper and lower surface metal layers of the lower dielectric substrate, are the same as the structures of the upper and lower surface metal layers of the upper dielectric substrate.

2. The dual-wideband linear-polarized to circular-polarized electromagnetic surface according to claim 1, characterized in that, The axial bandwidth of the electromagnetic surface is optimized for both normal and oblique incidence by scaling the size of the forward patch metal units in the upper, middle, and / or lower dielectric substrates.

3. The dual-wideband linear-polarized to circular-polarized 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-wideband linear-polarized to circular-polarized electromagnetic surface according to claim 1, characterized in that, The three dielectric substrates are all the same size, and the metal layers on the lower surface of the three dielectric substrates are all the same size; the metal units on the upper surface of the middle dielectric substrate and the lower dielectric substrate are all the same size. The size of the upper surface metal unit of the upper dielectric substrate is between 0.85 and 0.95 times the size of the upper surface metal unit of the middle and lower dielectric substrates.

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

6. The dual-wideband linear-polarized to circular-polarized 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 to 1 mm.

7. The dual-wideband linear-polarized to circular-polarized 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. The arrangement period p ranges from 0.50λ0≤p≤0.80λ0, where λ0 is the free space wavelength corresponding to the center frequency of the complete operating frequency band.

8. The dual-wideband linear-polarized to circular-polarized 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 of the complete working frequency band.

9. The dual-wideband linear-polarized to circular-polarized electromagnetic surface according to claim 1, characterized in that, The electromagnetic surface operates in the K / Ka frequency band.

10. The dual-wideband linear-polarized to circular-polarized electromagnetic surface according to claim 1, characterized in that, The electromagnetic surface is provided with through holes around its perimeter for positioning.

Images