A six-element rotating circularly polarized antenna array with high port isolation

Abstract

This invention discloses a six-element rotating circularly polarized antenna array with high port isolation, comprising a dielectric substrate (1), six radiating patches (2) located above the dielectric substrate, and a metal ground (3) located below the dielectric substrate; each of the radiating patches (2) is a regular hexagonal metal patch, and the six radiating patches (2) are rotationally symmetrical about the center of the dielectric substrate; a decoupling dual-line structure is provided between any two adjacent radiating patches (2); the decoupling dual-line structure includes two mutually coupled microstrip lines, each microstrip line comprising two segments, and the two segments forming a 120-degree angle. This invention effectively improves the isolation between antenna ports by placing the dual decoupling line structure between antenna elements, thus achieving a decoupling design.

Description

Technical Field

[0001] This invention relates to circularly polarized antenna arrays, and more particularly to a six-element rotating circularly polarized antenna array with high port isolation. Background Technology

[0002] Circularly polarized antenna arrays play a crucial role in satellite navigation systems. Compared to linearly polarized antenna arrays, circularly polarized arrays offer superior anti-interference and multipath resistance, which is essential for ensuring stable satellite signal transmission in complex environments. In practical applications, the use of circularly polarized antenna arrays enables satellite navigation systems to provide more accurate positioning information, playing an irreplaceable role in numerous fields such as vehicle navigation, aviation navigation, and military applications. However, to meet the high integration requirements of satellite navigation systems, the layout space of circularly polarized antenna arrays is compressed, and the size of the antenna array is reduced. This leads to a compression of the spacing between antenna array elements and causes strong coupling effects between array elements. The coupling effect between antenna elements causes a serious deterioration in the antenna's radiation performance, specifically manifested as a deterioration in the axial ratio performance of the circularly polarized antenna, an increase in the cross-polarization level, and a degradation in the achievable gain.

[0003] Compared to linearly polarized antenna arrays, decoupling circularly polarized antenna arrays is more challenging because maintaining the low axial ratio of the circularly polarized antenna is necessary during decoupling. Furthermore, for compactly arranged circularly polarized antennas, traditional decoupling structures are generally difficult to integrate coplanarly, and loading traditional decoupling structures increases the antenna array's profile. Therefore, the design of decoupling structures for circularly polarized antennas has always been a key challenge in this field. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a six-element rotating circularly polarized antenna array with high port isolation. By placing a dual decoupling line structure between the antenna elements, the isolation between the antenna ports can be effectively improved, thus achieving a decoupling design.

[0005] The objective of this invention is achieved through the following technical solution: a six-element rotating circularly polarized antenna array with high port isolation, comprising a dielectric substrate, six radiating patches located above the dielectric substrate, and a metal ground located below the dielectric substrate.

[0006] Each of the aforementioned radiating patches is a regular hexagonal metal patch, and the six aforementioned radiating patches are rotated symmetrically around the center of the dielectric substrate;

[0007] A decoupling bilinear structure is provided between any two adjacent radiating patches; the decoupling bilinear structure includes two mutually coupled microstrip lines, each microstrip line comprising two segments, with the two segments forming a 120-degree angle;

[0008] For any two adjacent radiating patches, the first segment of the first microstrip line is parallel to the first segment of the second microstrip line, and the first segment of the first microstrip line and the first segment of the second microstrip line are located between the adjacent edges of the two radiating patches; the second segment of the first microstrip line extends in opposite directions to the second segment of the second microstrip line.

[0009] The center-to-center spacing between any two adjacent antenna array elements is a fixed value. Preferably, the center-to-center spacing between any two adjacent antenna array elements is a fixed value of 75.5 mm. Each radiating patch is rotated symmetrically around the center of the dielectric substrate at an angle of 60°.

[0010] The dielectric substrate is provided with a power supply probe corresponding to each radiating patch; the metal ground is provided with multiple openings, each opening is equipped with an SMA connector, and the number of SMA connectors is the same as the number of power supply probes and they correspond one-to-one.

[0011] One end of the power supply probe is connected to the corresponding radiating patch, and the other end of the power supply probe is connected to the corresponding SMA connector.

[0012] The radiating patch has four rectangular slots; two of the rectangular slots are located at opposite vertices of the radiating patch, and the other two rectangular slots are located on the two opposite sides of the radiating patch, and the line connecting the rectangular slots on the sides to the center of the radiating patch is perpendicular to the line connecting the rectangular slots at the vertices to the center of the radiating patch.

[0013] Each radiating patch, along with the dielectric substrate, metal ground, and corresponding feed probe and SMA connector, constitutes an array antenna unit.

[0014] The beneficial effects of this invention are as follows: The antenna element of this invention adopts the form of a hexagonal circularly polarized microstrip patch antenna, and the six antenna elements are arranged in a rotationally symmetrical manner around the array center, ensuring that the coupling of each antenna element is consistent. Furthermore, this invention proposes a novel dual decoupling line structure. By placing the dual decoupling line structure between the antenna elements, the isolation between the antenna ports can be effectively improved, achieving decoupling. At the same time, after using this dual decoupling line structure, the axial ratio performance and achievable gain of the circularly polarized antenna element are significantly improved. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the principle of the present invention;

[0016] Figure 2 A schematic diagram of a six-element circularly polarized antenna array with a rotationally symmetric layout;

[0017] Figure 3 This is a top view of the antenna array unit;

[0018] Figure 4 This is a schematic diagram of the coupling coefficient between antenna array element 1 and its adjacent antenna array elements;

[0019] Figure 5 This is a schematic diagram showing the reflection coefficient and axial ratio of antenna array element 1 in the array;

[0020] Figure 6 This diagram illustrates the main polarization gain of antenna array element 1 in the array and the main polarization gain when the antenna array element exists alone.

[0021] Figure 7 This is a schematic diagram of a decoupled bilinear structure;

[0022] Figure 8 This is a schematic diagram of using a decoupled dual-line structure in a circularly polarized antenna array with a six-element rotational symmetry layout.

[0023] Figure 9 A schematic diagram illustrating the principle of achieving coupling suppression between antenna array elements using a decoupled dual-wire structure;

[0024] Figure 10 A schematic diagram of simulation and test results for the reflection coefficient of antenna array element 1 before and after the decoupled dual-line structure;

[0025] Figure 11 A schematic diagram illustrating the simulation and test results of increasing the coupling coefficient between antenna array element 1 and its adjacent elements in the decoupled dual-line structure.

[0026] Figure 12 A schematic diagram of the simulation and test results of the axial ratio of antenna array element 1 before and after increasing the decoupled dual-line structure;

[0027] Figure 13 A schematic diagram of simulation and test results of the radiation patterns of the antenna array unit 1 in the XOZ and YOZ planes with the main polarization and cross polarization of the decoupled dual-line structure. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0029] like Figure 1As shown, a six-element rotating circularly polarized antenna array with high port isolation includes a dielectric substrate 1, six radiating patches 2 located above the dielectric substrate, and a metal ground 3 located below the dielectric substrate.

[0030] Each of the aforementioned radiating patches 2 is a regular hexagonal metal patch, and the six aforementioned radiating patches 2 are rotated symmetrically around the center of the dielectric substrate;

[0031] A decoupling bilinear structure is provided between any two adjacent radiating patches 2; the decoupling bilinear structure includes two mutually coupled microstrip lines, each microstrip line includes two segments, and the two segments form a 120-degree angle;

[0032] For any two adjacent radiating patches 2, the first segment 6 of the first microstrip line is parallel to the first segment 8 of the second microstrip line, and the first segment 6 of the first microstrip line and the first segment 8 of the second microstrip line are located between the adjacent edges of the two radiating patches 2; the second segment 7 of the first microstrip line and the second segment 9 of the second microstrip line extend in opposite directions.

[0033] like Figure 2 As shown, each radiating patch, together with the dielectric substrate, the metal ground, and the corresponding feed probe and SMA connector, constitutes an array antenna element.

[0034] like Figure 3 The image shows a top view of the antenna array element. The radiating patch element adopts the form of a hexagonal patch antenna; the dielectric substrate has a relative permittivity of 5.9 and a thickness of 1.6 mm. The radiating patch is made of copper, and the feed point is connected to the inner conductor of the SMA connector used for coaxial feeding via a feed probe. The center frequency of the antenna array element is 1.265 GHz, and the polarization is left-hand circular polarization. Specific structural parameters are shown in Table 1.

[0035] Table 1 Specific structural parameters of the antenna array unit

[0036]

[0037] When the antenna array element exists independently, its reflection coefficient is below -20dB at 1.265GHz. Furthermore, at 1.265GHz, the axial ratio of the antenna array element is approximately 0.8dB, exhibiting excellent circularly polarized radiation characteristics.

[0038] A six-element circularly polarized antenna array is constructed using the aforementioned antenna array elements. The center-to-center spacing between the antenna array elements is 75.5 mm, and each element rotates 60° around the array's geometric center, resulting in a rotationally symmetric layout. The dielectric substrate of the six-element circularly polarized antenna array has a relative permittivity of 5.9 and a thickness of 1.6 mm. A key characteristic of this rotationally symmetric six-element circularly polarized antenna array is that the relative positional relationship between each antenna array element and all other antenna array elements is consistent. For example, the relative positional relationship between antenna array element 1 and antenna array elements 2 and 6 is consistent with the relative positional relationship between antenna array element 3 and antenna array elements 2 and 4. Therefore, the coupling influence of other elements on each antenna array element is essentially the same.

[0039] Taking antenna array element 1 as an example, the coupling coefficient between antenna array element 1 and its adjacent antenna array elements (antenna array element 2 and antenna array element 6) is as follows: Figure 4 As shown, at a center frequency of 1.265 GHz, the coupling coefficients between antenna array element 1 and antenna array element 2, as well as antenna array element 6, are all approximately -12.5 dB. Due to the coupling effect, the performance of antenna array element 1 deteriorates, with its reflection coefficient and aspect ratio as follows: Figure 5 As shown in the diagram, due to coupling within the array, the axial ratio of antenna array element 1 deteriorates from 0.8 dB to 2.6 dB compared to when it exists independently. Furthermore, due to coupling, the main polarization gain of antenna array element 1 is severely degraded, as follows: Figure 6 As shown, the gain of the main polarization of antenna array element 1 when it exists alone is approximately 4.6 dBic. However, in the six-element rotationally symmetric antenna array, the gain of the main polarization of antenna array element 1 is degraded to 2 dBic due to coupling effects.

[0040] To suppress coupling between adjacent antenna array elements in a six-element rotationally symmetric circularly polarized antenna array, this invention proposes a novel decoupling dual-line structure, the structure of which is as follows: Figure 7 As shown. The antenna array element is a regular hexagon, and a decoupling dual-line structure is provided between any two adjacent antenna array elements; the decoupling dual-line structure includes two mutually coupled microstrip lines, each microstrip line including two segments, and the two segments are at a 120-degree angle;

[0041] For any two adjacent antenna array elements, the first segment 6 of the first microstrip line is parallel to the first segment 8 of the second microstrip line and is located between the adjacent sides of the two antenna array elements; the second segment 7 of the first microstrip line and the second segment 9 of the second microstrip line extend in opposite directions.

[0042] The decoupling dual-wire structure is made of metallic copper. Placing the decoupling dual-wire structure between adjacent antenna array elements in a six-element rotationally symmetric circularly polarized antenna array can effectively suppress coupling effects. A schematic diagram is shown below. Figure 8 As shown in Table 2, the physical structural parameters of the decoupled bilinear structure are as follows.

[0043] Table 2 Physical structural parameters of the decoupled bilinear structure

[0044]

[0045]

[0046] The decoupling dual-line structure proposed in this invention is arranged between adjacent antenna array elements in a six-element rotationally symmetric circularly polarized antenna array (without being connected to the antenna array elements), thereby suppressing coupling between adjacent antenna array elements and improving the radiation performance of the antenna array elements in the array. The working principle is explained using antenna array element 1 and antenna array element 2 as examples, as follows: Figure 9 As shown, in a six-element rotationally symmetric circularly polarized antenna array, the scattered field generated by the decoupling dual-line structure has the same amplitude and a 180° phase difference with the original spatial coupling field of the adjacent antenna array elements. Their superposition cancels each other out, thus achieving cancellation of the spatial coupling fields of adjacent array antenna elements. Furthermore, the decoupling dual-line structure can perturb the surface field of the metal ground, thereby blocking the propagation of coupled surface waves formed by the metal ground through adjacent antenna array elements. In summary, the decoupling dual-line structure can cancel the original spatial coupling fields of adjacent antenna array elements and block the propagation of coupled surface waves formed by the metal ground, thus achieving coupling suppression between adjacent antenna array elements in a six-element rotationally symmetric circularly polarized antenna array.

[0047] The simulation and test results of the reflection coefficient of antenna array element 1 in a six-element rotationally symmetric circularly polarized antenna array before and after adding the decoupled dual-wire structure are as follows: Figure 10 As shown. After adding the decoupled dual-wire structure, the impedance matching bandwidth (S11 < -10dB) of antenna array element 1 can cover 1.26-1.27GHz. The simulation and test results of the coupling coefficient between antenna array element 1 and its adjacent elements before and after adding the decoupled dual-wire structure are as follows. Figure 11As shown, under the effect of the decoupled dual-line structure, at 1.265 GHz, the coupling coefficient between antenna array element 1 and antenna array element 2 decreases from -12.5 dB to -48 dB, and the coupling coefficient between antenna array element 1 and antenna array element 6 decreases from -12.5 dB to -38 dB. In the 1.265 GHz six-element rotationally symmetric circularly polarized antenna array, the isolation between adjacent elements is improved by more than 25.5 dB, and the isolation is maintained above 30 dB.

[0048] The simulation and test results of the axial ratio of antenna array element 1 before and after adding the decoupled dual-wire structure are as follows: Figure 12 As shown. At 1.265 GHz, after using the decoupled dual-wire structure, the axial ratio of antenna array element 1 decreased from 2.6 dB to 1.5 dB, and the circular polarization radiation characteristics were effectively improved.

[0049] The radiation patterns of antenna array element 1 before and after adding the decoupled dual-wire structure in the XOZ and YOZ planes with the main polarization (left-hand circular polarization, LHCP) and cross polarization (right-hand circular polarization, RHCP) are as follows. Figure 13 As shown, at a center frequency of 1.265 GHz, the peak gain achievable by the main polarization (LHCP) of antenna array element 1 after using the decoupled dual-wire structure is 4.1 dBic, which is more than 2 dB higher than the result before decoupling. Furthermore, the achievable gain of the cross polarization (RHCP) is effectively reduced, with the peak value decreasing from 0.5 dBic to -13 dBic.

[0050] The six-element circularly polarized antenna array proposed in this invention adopts a rotationally symmetric layout, which ensures that the influence of coupling between each antenna array element and other antenna array elements is basically consistent.

[0051] (1) The six-element rotationally symmetric circularly polarized antenna array designed in this invention adopts a novel decoupled dual-line structure. The decoupled dual-line structure can be placed between adjacent antenna array elements in the six-element rotationally symmetric circularly polarized antenna array to achieve excellent coupling suppression and improve the isolation between adjacent antenna array elements. It has been verified that the isolation between adjacent antenna array elements at a center frequency of 1.265 GHz can be improved by 25.5 dB.

[0052] (2) After using the decoupled dual-line structure in this invention, the isolation of adjacent antenna array elements can be improved, the axial ratio performance of the antenna array elements can be improved, the main polarization achievable gain of the antenna array elements can be greatly improved, and the cross-polarization achievable gain can be suppressed.

[0053] The above description represents preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technical or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A six-element rotating circularly polarized antenna array with high port isolation, characterized in that: It includes a dielectric substrate (1), six radiating patches (2) located above the dielectric substrate, and a metal ground (3) located below the dielectric substrate. Each of the aforementioned radiating patches (2) is a regular hexagonal metal patch, and the six aforementioned radiating patches (2) are rotationally symmetrical around the center of the dielectric substrate; A decoupling double-line structure is provided between any two adjacent radiating patches (2); the decoupling double-line structure includes two microstrip lines coupled to each other, each microstrip line includes two segments, and the two segments form a 120-degree angle; For any adjacent radiating patch (2), the first segment (6) of the first microstrip line is parallel to the first segment (8) of the second microstrip line, and the first segment (6) of the first microstrip line and the first segment (8) of the second microstrip line are located between the adjacent edges of the two radiating patches (2); the second segment (7) of the first microstrip line and the second segment (9) of the second microstrip line extend in opposite directions.

2. A six-element rotating circularly polarized antenna array with high port isolation according to claim 1, characterized in that: Each radiating patch, together with a dielectric substrate, a metal ground, and a corresponding feed probe and SMA connector, constitutes an antenna array unit. The center-to-center distance between any two adjacent antenna array units is a fixed value.

3. A six-element rotating circularly polarized antenna array with high port isolation according to claim 2, characterized in that: Each radiating patch is rotated symmetrically around the center of the dielectric substrate at an angle of 60°.

4. A six-element rotating circularly polarized antenna array with high port isolation according to claim 2, characterized in that: The center-to-center distance between any two adjacent antenna array elements is a fixed value of 75.5 mm.

5. A six-element rotating circularly polarized antenna array with high port isolation according to claim 1, characterized in that: The dielectric substrate (1) is provided with a feed probe (5) corresponding to each radiation patch (2); the metal ground (3) is provided with multiple openings, each opening is equipped with an SMA connector (4), and the number of SMA connectors (4) is the same as that of the feed probes (5) and they correspond one-to-one; One end of the power supply probe (5) is connected to the corresponding radiation patch (2), and the other end of the power supply probe (5) is connected to the corresponding SMA connector (4).

6. A six-element rotating circularly polarized antenna array with high port isolation according to claim 4, characterized in that: The radiating patch (2) has four rectangular slots; two of the rectangular slots are located at opposite vertices of the radiating patch, and the other two rectangular slots are located on the two opposite sides of the radiating patch. The line connecting the rectangular slots on the sides to the center of the radiating patch (2) is perpendicular to the line connecting the rectangular slots at the vertices to the center of the radiating patch (2).

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