Six-element rotation layout circularly polarized antenna array with high port isolation

Abstract

The invention discloses a six-element rotary layout circularly polarized antenna array with high port isolation. The six-element rotary layout circularly polarized antenna array comprises a dielectric substrate (1), six radiation patches (2) located above the dielectric substrate, and a metal ground (3) located below the dielectric substrate, each radiation patch (2) is a regular hexagonal metal patch, and the six radiation patches (2) are rotationally symmetrical around the center of the dielectric substrate; a decoupling double-line structure is arranged between any two adjacent radiation patches (2); the decoupling double-line structure comprises two microstrip lines which are coupled with each other, each microstrip line comprises two sections, and an included angle of 120 degrees is formed between the two sections. According to the invention, the double-decoupling-line structure is arranged between the antenna units, so that the isolation degree between antenna ports can be effectively improved, and the decoupling design is realized.

Description

Technical Field

[0001] The present invention relates to a circularly polarized antenna array, and particularly to a six - element rotating layout circularly polarized antenna array with high port isolation. Background Art

[0002] Circularly polarized antenna arrays play a crucial role in satellite navigation systems. Compared with linearly polarized antenna arrays, circularly polarized antenna arrays have excellent anti - interference performance and anti - multipath effect performance, which is crucial for ensuring the stable transmission of satellite signals in complex environments. In practical applications, the application of circularly polarized antenna arrays enables satellite navigation systems to provide more accurate positioning information and has an irreplaceable role in many fields such as vehicle navigation, aviation navigation, and military applications. However, in order to meet the requirements of high integration of satellite navigation systems, the layout space of circularly polarized antenna arrays is compressed, the size of the antenna array becomes smaller, resulting in the compression of the antenna array element spacing and causing strong coupling effects among the array elements. The coupling effect between antenna elements will cause serious deterioration of the radiation performance of the antenna, specifically manifested as the deterioration of the axial ratio performance of the circularly polarized antenna, the increase of the cross - polarization level, and the deterioration of the achievable gain.

[0003] Compared with linearly polarized antenna arrays, it is more difficult to decouple circularly polarized antenna arrays because it is necessary to maintain a low axial ratio level of the circularly polarized antenna while decoupling. In addition, for tightly arranged circularly polarized antennas, traditional decoupling structures are generally difficult to be integrated coplanarly, and the loading of traditional decoupling structures will lead to an increase in the profile of the antenna array. Therefore, the design of the decoupling structure for circularly polarized antennas has always been a key difficulty in the related field. Summary of the Invention

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

[0005] The purpose of the present invention is achieved by the following technical solutions: A six - element rotating layout circularly polarized antenna array with high port isolation, including a dielectric substrate, six radiation patches located above the dielectric substrate, and a metal ground located below the dielectric substrate;

[0006] Each of the radiation patches is a regular hexagonal metal patch, and the six radiation patches are rotationally symmetric around the center of the dielectric substrate;

[0007] A decoupling two - line structure is provided between any two adjacent radiation patches; the decoupling two - line structure includes two mutually coupled microstrip lines, each microstrip line includes two segments, and the angle between the two segments is 120 degrees;

[0008] For any two adjacent radiation 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 sides of the two radiation patches; the second segment of the first microstrip line and the extension direction of the second segment of the second microstrip line are opposite.

[0009] Among them, the center - to - center spacing of any two adjacent antenna array units is a fixed value. Preferably, the center - to - center spacing of any two adjacent antenna array units is a fixed value of 75.5 mm. The angle of rotational symmetry of each radiation patch around the center of the dielectric substrate is 60°.

[0010] A feeding probe corresponding to each radiation patch is provided in the dielectric substrate; a plurality of openings are provided in the metal ground, and each opening is equipped with an SMA connector, and the number of SMA connectors is the same as and corresponds one - to - one with the number of feeding probes.

[0011] One end of the feeding probe is connected to the corresponding radiation patch, and the other end of the feeding probe is connected to the corresponding SMA connector.

[0012] Four rectangular slots are provided on the radiation patch; two of the rectangular slots are located at the opposite vertices of the radiation patch, and the other two rectangular slots are located on the two opposite sides of the radiation patch, and the line connecting the rectangular slot on the side to the center of the radiation patch is perpendicular to the line connecting the rectangular slot at the vertex to the center of the radiation patch.

[0013] Each radiation patch, together with the dielectric substrate, the metal ground, and the corresponding feeding probe and SMA connector, constitutes an array antenna unit.

[0014] The beneficial effects of the present invention are as follows: The antenna unit of the present invention adopts the form of a hexagonal circularly polarized microstrip patch antenna, and six antenna units adopt a rotationally symmetric layout form around the array center, ensuring that the coupling situation of each antenna unit is the same. In addition, the present invention proposes a new type of double - decoupling line structure. By placing the double - decoupling line structure between antenna units, the isolation degree between antenna ports can be effectively improved to achieve decoupling. At the same time, after using this double - decoupling line structure, the axial ratio performance and achievable gain of the circularly polarized antenna unit are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0017] Figure 3 Top view of the antenna array element;

[0018] Figure 4 Schematic diagram of the coupling coefficient between antenna array element 1 and adjacent antenna array elements;

[0019] Figure 5 Schematic diagram of the reflection coefficient and axial ratio of antenna array element 1 in the array;

[0020] Figure 6 Schematic diagram of 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 Schematic diagram of the decoupling two - wire structure;

[0022] Figure 8 Schematic diagram of applying the decoupling two - wire structure to a circularly polarized antenna array with a six - element rotationally symmetric layout;

[0023] Figure 9 Schematic diagram of the principle of the decoupling two - wire structure to achieve coupling suppression between antenna array elements;

[0024] Figure 10 Schematic diagram of the simulation and test results of the reflection coefficient of antenna array element 1 before and after adding the decoupling two - wire structure;

[0025] Figure 11 Schematic diagram of the simulation and test results of the coupling coefficient between antenna array element 1 and its adjacent elements before and after adding the decoupling two - wire structure;

[0026] Figure 12 Schematic diagram of the simulation and test results of the axial ratio of antenna array element 1 before and after adding the decoupling two - wire structure;

[0027] Figure 13 Schematic diagram of the simulation and test results of the main polarization and cross - polarization radiation patterns of antenna array element 1 in the XOZ and YOZ planes before and after adding the decoupling two - wire structure. Specific implementation mode

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

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

[0030] Each of the radiation patches 2 is a regular hexagonal metal patch, and the six radiation patches 2 are rotationally symmetric about the center of the dielectric substrate;

[0031] A decoupling double - line structure is provided between any two adjacent radiation patches 2; the decoupling double - line structure includes two mutually coupled microstrip lines, and each microstrip line includes two segments, and the angle between the two segments is 120 degrees;

[0032] For any two adjacent radiation 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 sides of the two radiation patches 2; the extension directions of the second segment 7 of the first microstrip line and the second segment 9 of the second microstrip line are opposite.

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

[0034] As Figure 3 shown, it is a top view of the antenna array element. The radiation patch unit adopts the form of a hexagonal patch antenna; the relative dielectric constant of the dielectric substrate is 5.9, and the thickness is 1.6 mm. The material of the radiation patch is copper, and the feeding point is connected to the inner conductor of the SMA connector for coaxial feeding through a feeding probe. The center frequency of the antenna array element is 1.265 GHz, and the polarization mode is left - hand circular polarization. The specific structure parameters are shown in Table 1.

[0035] Table 1 Specific structure parameters of the antenna array element

[0036]

[0037] When the antenna array element exists independently, at 1.265 GHz, the reflection coefficient of the antenna array element is below - 20 dB. In addition, at 1.265 GHz, the axial ratio of the antenna array element is about 0.8 dB, having excellent circularly polarized radiation characteristics.

[0038] The above-mentioned antenna array units are used to form a six-element circularly polarized antenna array. The center spacing between the antenna array units in the six-element circularly polarized antenna array is 75.5 mm, and the angle by which each antenna array unit rotates around the geometric center of the array is 60°, so that the six antenna elements form a rotationally symmetric layout. The relative dielectric constant of the dielectric substrate of the six-element circularly polarized antenna array is 5.9, and the thickness is 1.6 mm. The characteristic of the circularly polarized antenna array with a six-element rotationally symmetric layout is that the relative positional relationship between each antenna array unit in the array and other antenna array units except itself is the same. Taking antenna array unit 1 as an example, the relative positional relationship between antenna array unit 1 and antenna array unit 2 and antenna array unit 6 is the same as the relative positional relationship between antenna array unit 3 and antenna array unit 2 and antenna array unit 4. Therefore, the coupling influence of each antenna array unit by other units is basically the same.

[0039] Here, taking antenna array unit 1 as an example, the coupling coefficients between antenna array unit 1 and its adjacent antenna array units (antenna array unit 2 and antenna array unit 6) are as follows Figure 4 As shown, at the center frequency of 1.265 GHz, the coupling coefficients between antenna array unit 1 and antenna array unit 2 and antenna array unit 6 are both about -12.5 dB. Affected by the coupling, the performance of antenna array unit 1 will deteriorate, and its reflection coefficient and axial ratio are as follows Figure 5 As shown. It can be seen that in the array, affected by the coupling, the axial ratio of antenna array unit 1 deteriorates from 0.8 dB to 2.6 dB compared with when it exists independently. In addition, affected by the coupling, the main polarization gain of antenna array unit 1 will deteriorate severely, as follows Figure 6 As shown. It can be seen that the achievable main polarization gain of antenna array unit when it exists alone is about 4.6 dBic. In the antenna array with a six-element rotationally symmetric layout, the achievable main polarization gain of antenna array unit 1 deteriorates to 2 dBic due to the coupling influence.

[0040] In order to suppress the coupling between adjacent antenna array units in the circularly polarized antenna array with a six-element rotationally symmetric layout, the present invention proposes a novel decoupling double-line structure, and its structure is as follows Figure 7 As shown. The antenna array unit is a regular hexagon, and a decoupling double-line structure is provided between any two adjacent antenna array units; the decoupling double-line structure includes two mutually coupled microstrip lines, and each microstrip line includes two segments, and the angle between the two segments is 120 degrees;

[0041] For any two adjacent antenna array elements, the first section 6 of the first microstrip line is parallel to the first section 8 of the second microstrip line and is located between the adjacent sides of the two antenna array elements; the second section 7 of the first microstrip line has an extension direction opposite to that of the second section 9 of the second microstrip line.

[0042] The material of the decoupling two-wire structure is copper. Placing the decoupling two-wire structure between adjacent antenna array elements in a six-element rotationally symmetric circularly polarized antenna array can effectively suppress the coupling effect. The schematic diagram is as follows Figure 8 shown. The physical structure parameters of the decoupling two-wire structure are shown in Table 2 below.

[0043] Table 2 Physical structure parameters of the decoupling two-wire structure

[0044]

[0045]

[0046] The proposed decoupling two-wire structure of the present invention is arranged between adjacent antenna array elements of a six-element rotationally symmetric circularly polarized antenna array (not connected to the antenna array elements), realizing the coupling suppression between adjacent antenna array elements and improving the radiation performance of the antenna array elements in the array. Taking antenna array element 1 and antenna array element 2 as examples, the principle of its action is described as follows Figure 9 shown. In a six-element rotationally symmetric circularly polarized antenna array, the scattering field generated by the decoupling two-wire structure has the same amplitude and a phase difference of 180° from the original spatial coupling field of the adjacent antenna array element. After the two are superimposed, they cancel each other out, thus realizing the cancellation of the spatial coupling field of the adjacent array antenna elements. In addition, the decoupling two-wire structure can produce a perturbation effect on the surface field of the metal ground, thereby blocking the propagation of the coupled surface wave formed by the adjacent antenna array elements through the metal ground. To sum up, the decoupling two-wire structure can realize the cancellation of the original spatial coupling field between adjacent antenna array elements and block the propagation of the coupled surface wave formed by the metal ground, thereby realizing the coupling suppression between adjacent antenna array elements of 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 decoupling two-wire structure are as follows Figure 10 shown. After adding the decoupling two-wire structure, the impedance matching bandwidth (S11 < -10 dB) of antenna array element 1 can cover 1.26 - 1.27 GHz. The simulation and test results of the coupling coefficient between antenna array element 1 and its adjacent element before and after adding the decoupling two-wire structure are as follows Figure 11As shown, under the action of the decoupling two-wire structure, at 1.265 GHz, the coupling coefficient between antenna array element 1 and antenna array element 2 drops from -12.5 dB to -48 dB, and the coupling coefficient between antenna array element 1 and antenna array element 6 drops from -12.5 dB to -38 dB. In the six-element rotationally symmetric circularly polarized antenna array at 1.265 GHz, the isolation between adjacent array elements is improved by more than 25.5 dB, and the isolation remains above 30 dB.

[0048] The simulation and test results of the axial ratio of antenna array element 1 before and after adding the decoupling two-wire structure are as follows Figure 12 As shown. At 1.265 GHz, after using the decoupling two-wire structure, the axial ratio of antenna array element 1 drops from 2.6 dB to 1.5 dB, and the circularly polarized radiation characteristics are effectively improved.

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

[0050] The six-element circularly polarized antenna array proposed by the present invention adopts a rotationally symmetric layout, ensuring that the influence of the coupling of each antenna array element in the antenna array by other antenna array elements is basically the same;

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

[0052] (2) After using the decoupling two-wire structure of the present invention, while improving the isolation between adjacent antenna array elements, the axial ratio performance of the antenna array elements can be improved, the achievable gain of the main polarization of the antenna array elements can be greatly improved, and the achievable gain of the cross-polarization can be suppressed.

[0053] The above are the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein, should not be regarded as excluding other embodiments, but can be used in other combinations, modifications and environments, and can be changed within the scope of the concept described herein through the above teachings or the techniques or knowledge in the relevant field. Any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A six-element rotation layout circularly polarized antenna array with high port isolation, characterized in that: It comprises a dielectric substrate (1), six radiation patches (2) located above the dielectric substrate, and a metal ground (3) located below the dielectric substrate; Each of the radiation patches (2) is a regular hexagonal metal patch, and the six radiation patches (2) are rotationally symmetrical around the center of the dielectric substrate; A decoupling double-line structure is provided between any two adjacent radiation patches (2); the decoupling double-line structure comprises two mutually coupled microstrip lines, each microstrip line comprises two sections, and the two sections form an angle of 120 degrees; For any adjacent radiation 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 adjacent edges of the two radiation patches (2); and the second segment (7) of the first microstrip line and the second segment (9) of the second microstrip line extend in opposite directions.

2. The six-element rotated layout circularly polarized antenna array with high port isolation according to claim 1, characterized in that: The center distance between any two adjacent antenna array units is a fixed value.

3. The six-element rotated layout circularly polarized antenna array with high port isolation according to claim 2, characterized in that: The rotational symmetry angle of each radiation patch around the center of the dielectric substrate is 60°.

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

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

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

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