A polarisation converter based transmissive array antenna

Abstract

The application discloses a kind of transmission array antennas based on polarization converter, including polarization converter and linear polarization twist reflection surface of up and down arrangement.Polarization converter includes several adjustable phase polarization conversion surface units arranged periodically.Adjustable phase polarization conversion surface unit has polarization selection characteristics, when application frequency band, the incident y polarization electromagnetic wave is reflected, the incident x polarization electromagnetic wave is twisted and transmits out circularly polarized electromagnetic wave.The structure can be applied to folding array, reduce the overall profile of array.The transmission array antenna presented in the application can reduce one third of profile due to its polarization selection characteristics by introducing polarization converter.

Description

Technical Field

[0001] This invention belongs to the field of communication antennas, and specifically relates to a transmission array antenna. Background Technology

[0002] With the rapid development of satellite communication, millimeter-wave radar, and broadband wireless communication technologies, the demand for circularly polarized antennas that combine high gain, low profile, and anti-interference capabilities is becoming increasingly urgent. Traditional reflector antennas are bulky, and phased array antennas have complex feeding networks and high losses. In contrast, transmission array antennas achieve high-gain radiation through spatial feeding and element phase compensation, with a simple structure and easy conformal integration. Building on this, circularly polarized transmission array antennas achieve a 90° phase difference between orthogonal components and equal amplitude output through element structure design. This effectively suppresses multipath fading and polarization mismatch loss. While maintaining the advantages of low profile and lightweight design, it achieves high-efficiency and high-purity circularly polarized beam radiation, making it an important research direction for scenarios such as inter-satellite links, vehicle-mounted radar, and 5G / 6G millimeter-wave terminals.

[0003] Currently, existing technologies mostly employ simple single-layer or double-layer metal patch structures to achieve linear-to-circular polarization conversion, which are then combined with a transmission array to form an antenna. These structures generally suffer from narrow polarization conversion bandwidth, poor circular polarization axial ratio performance, and low transmission efficiency. Furthermore, polarization conversion and phase modulation are coupled, resulting in insufficient freedom in unit phase modulation, making it difficult to achieve good beam focusing performance while maintaining high polarization purity. In addition, existing structures struggle to balance bandwidth, efficiency, and profile, failing to meet the application requirements of broadband, high-efficiency, and high-gain circularly polarized transmission array antennas. Summary of the Invention

[0004] Purpose of the invention: In view of the above-mentioned prior art, a transmission array antenna based on a polarization converter is proposed, which can achieve a wide bandwidth at a low profile and realize polarization conversion, torsion and selection performance.

[0005] Technical solution: A transmission array antenna based on a polarization converter includes a polarization converter and a linearly polarized torsional reflective surface arranged vertically. A linearly polarized feed horn is arranged at the center of the linearly polarized torsional reflective surface. The polarization converter includes several periodically arranged tunable phase polarization conversion surface units.

[0006] Furthermore, the tunable phase polarization conversion surface unit includes, from top to bottom, a top metal layer, a dielectric substrate one, a metal ground layer, a dielectric substrate two, an intermediate metal layer, an upper metal grid layer, a dielectric substrate three, a lower metal layer, a dielectric substrate four, and a lower metal grid layer; it also includes a metal via located at the very center of the tunable phase polarization conversion surface unit for connecting the top metal layer and the intermediate metal layer;

[0007] The top metal layer consists of a set of rectangular metal patches with triangular openings at their diagonals and a C-shaped slit in the center; the upper metal grid layer is a grid structure composed of several parallel rectangular metal strips; the lower metal layer is a bidirectional arrow-shaped metal patch array; the lower metal grid layer is a grid structure composed of several parallel rectangular metal strips, and the strip direction is perpendicular to the strips in the upper metal grid layer.

[0008] Furthermore, the linearly polarized torsional reflective surface includes a metal patch layer, a dielectric substrate layer, and a metal ground layer stacked sequentially from top to bottom; wherein, the metal patch layer is provided with an array of I-shaped patches with arc-shaped ends, which are used to realize the linear polarization torsion of the incident linearly polarized electromagnetic wave.

[0009] Furthermore, the feed horn outputs a y-polarized electromagnetic wave, which is incident on the lower surface of the polarization converter. The y-polarized electromagnetic wave is reflected onto the linearly polarized torsional reflector surface, which then reflects an x-polarized electromagnetic wave back to the lower surface of the polarization converter and transmits a circularly polarized electromagnetic wave from the upper surface.

[0010] Furthermore, in the tunable phase polarization conversion surface unit, the upper metal grid layer and the structure below it jointly achieve a 360° linear phase change, and the middle metal layer and the structure above it jointly achieve a conversion from linear polarization to circular polarization.

[0011] Furthermore, by adjusting the length of the bidirectional arrow-shaped metal patch in the lower metal layer and the direction of the arrow, 360° phase coverage can be achieved.

[0012] Furthermore, by optimizing the chamfer size of the patch in the top metal layer and the size of the C-shaped gap, the circular polarization effect is improved, and the conversion from linear polarization to circular polarization is achieved.

[0013] 8. The transmission array antenna according to claim 2, wherein the intermediate metal layer is a rectangular metal patch.

[0014] Furthermore, the intermediate metal layer is a circular patch with a C-shaped slit in the center.

[0015] Beneficial effects: 1. The tunable phase polarization conversion surface unit proposed in this invention has polarization selectivity characteristics, which can reflect the incident y-polarized electromagnetic wave and twist and transmit the incident x-polarized electromagnetic wave into a circularly polarized electromagnetic wave within the application frequency band.

[0016] 2. The tunable phase polarization conversion surface unit proposed in this invention can achieve 360° phase adjustment by changing the length and direction of the arrow-shaped metal patch in the lower metal layer, and can achieve linear phase in a wide frequency band.

[0017] 3. Due to its polarization selectivity, the profile of the transmission array antenna proposed in this invention can be reduced by one-third by introducing a polarization converter. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural schematic diagram of the transmission array antenna according to an embodiment of the present invention;

[0019] Figure 2 This is a side-view schematic diagram of the working principle of the transmission array antenna according to an embodiment of the present invention;

[0020] Figure 3 This is a top view schematic diagram of the polarization converter structure in an embodiment of the present invention;

[0021] Figure 4 This is a top view schematic diagram of the linearly polarized torsional reflective surface structure in an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the three-dimensional structure of the polarization conversion surface unit in an embodiment of the present invention;

[0023] Figure 6 This is a top view schematic diagram of the top metal layer structure of the polarization conversion surface unit in an embodiment of the present invention;

[0024] Figure 7 This is a top view schematic diagram of the metal stratum structure of the polarization conversion surface unit in an embodiment of the present invention;

[0025] Figure 8 This is a top view schematic diagram of the intermediate metal layer structure of the polarization conversion surface unit in an embodiment of the present invention;

[0026] Figure 9 This is a top view schematic diagram of the upper metal grid layer structure of the polarization conversion surface unit in an embodiment of the present invention;

[0027] Figure 10 This is a top view of the lower metal layer structure of the polarization conversion surface unit in an embodiment of the present invention;

[0028] Figure 11 This is a top view schematic diagram of the lower metal grid layer structure of the polarization conversion surface unit in an embodiment of the present invention;

[0029] Figure 12 This is a top view schematic diagram of the metal patch layer structure of the linearly polarized torsional reflective surface in an embodiment of the present invention;

[0030] Figure 13 This is a transmission coefficient performance diagram of the transmission array antenna in this embodiment;

[0031] Figure 14 This is a phase performance diagram of the transmission array antenna in this embodiment;

[0032] Figure 15 This is a phase compensation performance diagram of the transmission array antenna in this embodiment;

[0033] Figure 16 r is the r of the transmission array antenna in this embodiment. yx Reflectance coefficient performance diagram;

[0034] Figure 17 These are the E-plane and H-plane radiation patterns of the transmission array antenna in this embodiment at the center frequency;

[0035] Figure 18 This is a graph showing the gain and axial ratio of the transmission array antenna in this embodiment as a function of frequency.

[0036] In the figure, the following labels are used: 1-Adjustable phase polarization conversion surface unit; 2-Top metal layer; 3-Dielectric substrate one; 4-Metal ground layer; 5-Dielectric substrate two; 6-Intermediate metal layer; 7-Metal via; 8-Upper metal grid layer; 9-Dielectric substrate three; 10-Lower metal layer; 11-Dielectric substrate four; 12-Lower metal grid layer. Detailed Implementation

[0037] The invention will now be further explained with reference to the accompanying drawings.

[0038] like Figures 1 to 12 As shown, a transmission array antenna based on a polarization converter includes a polarization converter and a linearly polarized torsional reflector arranged vertically. The polarization converter includes several periodically arranged tunable phase polarization conversion surface elements 1. A linearly polarized feed horn is disposed at the central hollowed-out portion of the linearly polarized torsional reflector.

[0039] The tunable phase polarization conversion surface unit 1 includes, from top to bottom, a top metal layer 2, a dielectric substrate 3, a metal ground layer 4, a dielectric substrate 5, an intermediate metal layer 6, an upper metal grid layer 8, a dielectric substrate 9, a lower metal layer 10, a dielectric substrate 11, and a lower metal grid layer 12, and also includes a metal via 7. The metal via 7 is located at the very center of the tunable phase polarization conversion surface unit 1 and is used to connect the top metal layer 2 and the intermediate metal layer 6.

[0040] The top metal layer 2 consists of a set of diagonally etched triangular openings on rectangular metal patches, with a C-shaped slit etched in the center. A circular hole is etched in the center of the metal base layer 4, through which a metal through-hole 7 passes. The middle metal layer 6 consists of rectangular metal patches. Both the upper metal grid layer 8 and the lower metal grid layer 12 are grid structures composed of several parallel rectangular metal strips, with the rectangular metal strips of the upper metal grid layer 8 and the lower metal grid layer 12 perpendicular to each other. The lower metal layer 10 is a 2×2 array of bidirectional arrowhead-shaped metal patches. An air layer is provided between the middle metal layer 6 and the upper metal grid layer 8.

[0041] like Figure 2 As shown, the feed horn outputs a y-polarized electromagnetic wave, which is incident on the lower surface of the polarization converter. Due to the polarization selectivity of the polarization converter, the y-polarized electromagnetic wave cannot pass through the structure and is reflected onto the linearly polarized torsional reflective surface. The linearly polarized torsional reflective surface torsional the y-polarized electromagnetic wave into an x-polarized electromagnetic wave, which is then reflected again onto the lower surface of the tunable phase polarization converter. Due to the polarization selectivity of the tunable phase polarization converter, the x-polarized electromagnetic wave is received by the lower metal grid layer 12 and transmitted to the top metal layer 2. The phase-compensated circularly polarized electromagnetic wave is transmitted from the top metal layer 2 into free space.

[0042] In this process, a 360° linear phase change is achieved through the upper metal grid layer 8 and the structure beneath it. Specifically, under linearly polarized wave incidence, 360° phase coverage is achieved by changing the length and arrow direction of the bidirectional arrow-shaped metal patch in the lower metal layer 10. Specifically, the length of the bidirectional arrow-shaped metal patch can alter the surface current path and resonant characteristics, enabling continuous phase modulation; the arrow direction of the bidirectional arrow-shaped metal patch can change the polarization conversion efficiency and phase response, expanding the phase modulation range.

[0043] The conversion from linear polarization to circular polarization is achieved through the intermediate metal layer 6 and the structure above it. Specifically, the top metal layer 2 introduces anisotropic resonance due to the patch, C-shaped slot, and chamfer, decomposing the incident electric field into two mutually orthogonal linear polarization components. By adjusting the size of the C-shaped slot and the chamfer, these two orthogonal components can produce outputs with approximately equal amplitudes and a phase difference close to 90°. When the condition of equal amplitude and 90° phase difference is met, the synthesized radiation field is a circularly polarized wave, thus achieving the conversion from linear polarization to circular polarization.

[0044] Furthermore, the tunable phase polarization conversion surface unit 1 can filter linearly polarized electromagnetic waves by changing the orientation of the intermediate metal layer 6, the upper metal grid layer 8, and the lower metal grid layer 12, rotating them 90° relative to each other. This satisfies the target polarization's resonant interference enhancement and suppresses radiation caused by orthogonal polarization phase mismatch, thus achieving polarization selection and purification while simultaneously achieving high-gain radiation.

[0045] The linearly polarized torsional reflective surface comprises a metal patch layer, a dielectric substrate layer, and a metal ground layer stacked sequentially from top to bottom. The metal patch layer has an array of I-shaped patches with arc-shaped ends, which can achieve linear polarization torsion after incident linearly polarized electromagnetic waves.

[0046] In the tunable phase polarization conversion surface unit 1, the height h1 of the dielectric substrate is 0.77mm~0.88mm, the air layer height h2 is 0.39mm~0.44mm, the side length p of the dielectric substrate is 4.83mm~5.47mm, the length a1 of the rectangular metal patch in the top metal layer is 2.32mm~2.63mm, the width b1 of the rectangular metal patch in the top metal layer is 2.32mm~2.63mm, the right-angled side length t of the triangular opening chamfer is 0.77mm~0.88mm, and the width Zh of the C-shaped gap is 0.29mm~0.33mm. The diameter d0 of the circular hole on the metal layer is 0.39mm~0.44mm, the length xxx of the middle metal layer is 2.32mm~2.63mm, the width yyy of the metal patch layer is 2.32mm~2.63mm, and the metal grid is 1.26mm~-1.42mm; the length aa of the arrowhead in the bidirectional arrow-shaped metal patch is 1.35mm~1.53mm, the strip width w of the bidirectional arrow-shaped metal patch is 0.19mm~0.22mm, and the strip width L1 of the I-shaped patch with arc ends is 0.48mm~0.55mm.

[0047] In this embodiment, the antenna parameters are shown in the table below:

[0048]

[0049] like Figure 5 As shown, the dielectric substrates 3 and 5 of the tunable phase polarization conversion surface unit 1 are made of the same material and have the same size, with a dielectric constant εr of 3.55 and a loss tangent tanδ of 0.002; the dielectric substrates 9 and 11 have a dielectric constant εr of 2.65 and a loss tangent tanδ of 0.003. Furthermore, the dielectric substrate layer of the linearly polarized torsional reflective surface has a dielectric constant εr of 3.55, a tanδ of 0.0027, and a height of 1.508 mm.

[0050] like Figure 13 , Figure 14 The figure shows the transmission coefficient and phase variation of the transmission array antenna in this embodiment within the frequency range, with the incident x-polarized wave and the transmitted x-polarized wave t. xx and incident x-polarized wave transmitted y-polarized wave t yx At a center frequency of 29 GHz, the amplitudes are -4 dB and the phase difference is 90°.

[0051] like Figure 15 The figure shows the phase change of the transmission position of the transmission array antenna in this embodiment after changing the length of aa within the frequency range, t xx and t yx At a center frequency of 29 GHz, the phase difference is 90°.

[0052] like Figure 16 As shown, the transmission array antenna in this embodiment has polarization torsion in the frequency range of 22GHz to 35GHz, and the reflection amplitude is greater than -1dB.

[0053] Figure 17 As shown, the main polarization of the transmission array antenna in this embodiment is about 15.3 dB at the center frequency of 29 GHz;

[0054] like Figure 18 As shown, in the frequency range of 26.5 GHz to 29 GHz, the transmission array antenna of this embodiment has a gain bandwidth of approximately 10% and a aperture efficiency of 14%.

[0055] In another embodiment, the intermediate metal layer 6 is a circular patch with a C-shaped slit in the center.

[0056] 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 transmission array antenna based on a polarization converter, characterized in that, It includes a polarization converter and a linearly polarized torsional reflector surface arranged vertically, with a linearly polarized feed horn disposed at the center of the linearly polarized torsional reflector surface; the polarization converter includes several tunable phase polarization conversion surface units arranged periodically (1).

2. The transmission array antenna according to claim 1, characterized in that, The tunable phase polarization conversion surface unit (1) includes a top metal layer (2), a dielectric substrate one (3), a metal ground layer (4), a dielectric substrate two (5), an intermediate metal layer (6), an upper metal grid layer (8), a dielectric substrate three (9), a lower metal layer (10), a dielectric substrate four (11), and a lower metal grid layer (12) stacked sequentially from top to bottom; it also includes a metal via (7) located at the center of the tunable phase polarization conversion surface unit (1) for connecting the top metal layer (2) and the intermediate metal layer (6); The top metal layer (2) consists of a set of rectangular metal patches with triangular openings at the diagonal and a C-shaped slit in the middle; the upper metal grid layer (8) consists of a grid structure composed of several parallel rectangular metal strips; the lower metal layer (10) consists of a bidirectional arrow-shaped metal patch array; the lower metal grid layer (12) consists of a grid structure composed of several parallel rectangular metal strips, and the strip direction is perpendicular to the strips in the upper metal grid layer (8).

3. The transmission array antenna according to claim 1, characterized in that, The linearly polarized torsional reflective surface includes a metal patch layer, a dielectric substrate layer, and a metal ground layer stacked sequentially from top to bottom; wherein, the metal patch layer is provided with an array of I-shaped patches with arc-shaped ends, which are used to realize the linear polarization torsion of the incident linearly polarized electromagnetic wave.

4. The transmission array antenna according to claim 2, characterized in that, The feed horn outputs a y-polarized electromagnetic wave, which is incident on the lower surface of the polarization converter. The y-polarized electromagnetic wave is reflected onto the linearly polarized torsional reflector surface, which then reflects an x-polarized electromagnetic wave back to the lower surface of the polarization converter and transmits a circularly polarized electromagnetic wave from the upper surface.

5. The transmission array antenna according to claim 2, characterized in that, In the adjustable phase polarization conversion surface unit (1), the upper metal grid layer (8) and the structure below it jointly realize a 360° linear phase change, and the middle metal layer (6) and the structure above it jointly realize the conversion from linear polarization to circular polarization.

6. The transmission array antenna according to claim 5, characterized in that, 360° phase coverage can be achieved by adjusting the length of the bidirectional arrow-shaped metal patch of the lower metal layer (10) and the direction of the arrow of the patch.

7. The transmission array antenna according to claim 5, characterized in that, By optimizing the chamfer size of the patch in the top metal layer (2) and the size of the C-shaped gap, the circular polarization effect is improved, and the conversion from linear polarization to circular polarization is achieved.

8. The transmission array antenna according to claim 2, characterized in that, The intermediate metal layer (6) is a rectangular metal patch.

9. The transmission array antenna according to claim 2, characterized in that, The intermediate metal layer (6) is a circular patch with a C-shaped slit in the middle.

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