Low-mutual-coupling Beidou antenna array

Abstract

The invention discloses a low-mutual-coupling Beidou antenna array which comprises an antenna array, a multifunctional metasurface and an antenna cover. The multifunctional metasurface is located between the antenna array and the antenna housing, the antenna array comprises a plurality of antenna array elements and a plurality of metal grounding columns, the plurality of metal grounding columns are arranged around the antenna array elements, and the plurality of antenna array elements are arranged and printed on a whole PCB to form the antenna array; the multifunctional metasurface comprises a plurality of interdigital-like units arranged periodically, each interdigital-like unit comprises a closed-loop gap structure arranged on the PCB, the closed-loop gap structure comprises a plurality of protrusions and recesses, and the protrusions and the recesses are alternately arranged on the inner side and the outer side of the closed-loop gap structure. According to the invention, the characteristic that the metasurface suppresses the propagation of specific frequency in the direction of an array plane is utilized, the mutual coupling between the antenna array elements is reduced, the signal-to-noise ratio of each array element is improved, and the same-frequency interference resistance of the Beidou anti-interference antenna array under the same size is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of satellite navigation systems and relates to a low mutual coupling Beidou antenna array. Background Art

[0002] With the continuous improvement of the domestic Beidou satellite navigation system and the increasing maturity of satellite application technology, the application of anti-interference antenna array technology has become more and more extensive, and the application scenarios have become more diversified, complex and miniaturized, which has also brought huge challenges to the realization of anti-interference antenna array performance. At the same time, with the increase in the complexity of the installation application scenario, the impact of a single antenna element on the anti-interference antenna performance has gradually deepened. Therefore, the anti-interference performance in compact, asymmetric and other unconventional environments (compact, asymmetric environments are prone to deterioration of the performance of single antenna elements, beam distortion, etc.) and reducing the mutual coupling between antenna elements have become increasingly important. Summary of the invention

[0003] The purpose of the present invention is to provide a low mutual coupling Beidou antenna array, which utilizes the property of a metasurface to suppress the propagation of specific frequencies in the direction of the array plane, reduces the mutual coupling between antenna elements, and improves the signal-to-noise ratio of each element, thereby improving the anti-same-frequency interference performance of the Beidou anti-interference antenna array of the same size.

[0004] In order to solve the above technical problems, the technical solution of the present invention is:

[0005] A low mutual coupling Beidou antenna array, comprising an antenna array, a multifunctional metasurface, and a radome;

[0006] The multifunctional metasurface is located between the antenna array and the antenna cover. The antenna array includes multiple antenna elements and multiple metal grounding posts. The multiple metal grounding posts are arranged around the antenna elements using a PCB metallization via process. The multiple antenna elements are arranged and printed on a whole PCB board to form the antenna array; the multifunctional metasurface includes multiple periodically arranged quasi-interdigitated units, each of which includes a closed-loop gap structure opened on the PCB board, and the closed-loop gap structure includes multiple protrusions and recesses, and the protrusions and recesses are alternately arranged on the inner and outer sides of the closed-loop gap structure.

[0007] Furthermore, the recess is arranged on the inner side of the closed-loop gap structure, and the protrusion is arranged on the outer side.

[0008] Furthermore, the closed-loop gap structure is a quadrilateral structure, and each side of the quadrilateral structure includes a protrusion and a recess.

[0009] Furthermore, each of the protrusions is correspondingly provided with a recess on the inner side of the closed-loop gap structure.

[0010] Furthermore, in the periodically arranged cross-finger-like units of a single antenna element, the recess lengths of the cross-finger-like units in the same column or the same row are the same, while the recess lengths of the cross-finger-like units in different columns or different rows are different.

[0011] Furthermore, the length of the closed-loop slot structure of the cross-finger-like unit is one-quarter of the dielectric wavelength.

[0012] Furthermore, the antenna element includes a dielectric substrate, a radiation patch, and a coaxial feeding probe. The bottom layer of the dielectric substrate is printed copper foil, and the upper layer of the dielectric substrate is the radiation patch. The antenna element receives a right-handed circularly polarized wave through the coaxial feeding probe and converts the free-space wave into a guided wave.

[0013] Furthermore, the antenna element adopts a chamfered single-feed microstrip antenna design, and the right-handed circular polarization characteristic of the element is realized through chamfering perturbation.

[0014] Furthermore, the number of antenna elements is four, and the four antenna elements are rotationally arranged and printed on a whole PCB board.

[0015] Compared with the prior art, the technical effects achieved by the present invention are as follows:

[0016] Through the composite integrated design of the decoupling metasurface, the performance of the Beidou anti-jamming antenna array system is improved, the anti-jamming ability is enhanced, the miniaturization of the antenna array is promoted, and thus the application scenarios of the Beidou anti-jamming antenna array are expanded.

[0017] 1. The present invention reduces the mutual coupling between the elements of the miniaturized Beidou anti-jamming antenna array through the design of the cross-finger-like units, and realizes the improvement of the isolation degree between the elements of the Beidou anti-jamming antenna array.

[0018] 2. It improves the problem of pattern deflection of the miniaturized Beidou anti-jamming antenna array caused by the asymmetry of the antenna element feeding structure, boundary, etc.

[0019] 3. By adjusting the beam direction of a single antenna element through the multifunctional metasurface (controlling the specific phase change of the metasurface can realize the beam adjustment of the antenna element), the problem of beam deflection of the element caused by the asymmetry of the antenna element boundary is solved, and better anti-jamming performance is achieved under the same array factor. The anti-jamming performance of the Beidou anti-jamming antenna array is greatly improved under the same antenna array size.

[0020] 4. It provides a new solution for the miniaturization of the Beidou anti-jamming antenna array, realizes a smaller antenna array size under the same anti-jamming performance index, and makes it adapt to the needs of more carriers. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG Figure 1 is a three-dimensional structural schematic diagram of a low-mutual-coupling Beidou antenna array;

[0022] Appendix Figure 2 Side view of the low mutual coupling Beidou antenna array;

[0023] Appendix Figure 3 Perspective view of the low mutual coupling Beidou antenna array;

[0024] Appendix Figure 4 Exploded view of the low mutual coupling Beidou antenna array;

[0025] Appendix Figure 5 Basic structure diagram of the conventional band - pass type metasurface unit;

[0026] Appendix Figure 6 Schematic diagram of the integrated multi - functional metasurface cladding;

[0027] Appendix Figure 7 Schematic diagram of the 3×3 multi - functional metasurface cladding;

[0028] Appendix Figure 8 For Figure 7 Schematic diagram showing that the slot structures in three states of [[ ]] become shorter from left to right;

[0029] Appendix Figure 9 Schematic diagram of the four - element antenna array

[0030] Appendix Figure 10 Front view of the antenna element;

[0031] Appendix Figure 11 Side view of the antenna element;

[0032] Appendix Figure 12 Schematic diagram of beam deviation correction of the beam before and after adding the multi - functional metasurface to a single antenna element;

[0033] Appendix Figure 13 Frequency on - off characteristic diagram of the metasurface in three states;

[0034] Appendix Figure 14 Transmission amplitude curve diagram of the multi - functional metasurface in three states;

[0035] Appendix Figure 15 Typical isolation degree change diagram without adding the multi - functional metasurface;

[0036] Appendix Figure 16 Typical isolation degree change diagram after adding the multi - functional metasurface;

[0037] Appendix Figure 17 Comparison diagram of anti - interference nulls of the antenna array with typical azimuth 0 and elevation 10° before and after adding the multi - functional metasurface. Detailed implementation manners

[0038] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] As shown Figure 1-9 in the figure, a low mutual coupling Beidou antenna array includes an antenna array, a multifunctional metasurface, and an antenna radome;

[0040] The multifunctional metasurface is located between the antenna array and the antenna radome. The antenna array includes four antenna elements and a plurality of metal ground posts. The plurality of metal ground posts are arranged around the antenna elements by means of PCB metallized vias to block the transmission path of induced current and improve the isolation between elements. The four antenna elements are arranged and printed on a whole PCB board to form the antenna array. The antenna elements adopt the design of a conventional chamfered single-fed microstrip antenna, and the right-handed circular polarization characteristic of the element is realized through chamfer perturbation. This scheme has a simple structure and is basically not affected by the assembly process, with stable performance and high product consistency; The multifunctional metasurface includes a plurality of periodically arranged cross-finger-like units. Each cross-finger-like unit includes a closed-loop slot structure ( Figure 6-8 the green slot in the figure) opened on the PCB board. The closed-loop slot structure includes a plurality of protrusions and depressions, and the protrusions and depressions are alternately arranged on the inner and outer sides of the closed-loop slot structure. The multifunctional metasurface is printed by single-sided PCB, and mature PCB printing technology is used to realize the adjustment of the metasurface structure details and efficient and stable production.

[0041] Figure 5 Based on the basic structure of a conventional band-pass metasurface unit, through the cross-finger-like slot design, the present invention can effectively adjust the slot length (the side length of the slot is generally about one-quarter of the dielectric wavelength) under the condition that the unit period size remains unchanged and the slot width is basically unchanged, so as to achieve a lower passband frequency, thereby realizing the miniaturization design of the metasurface unit (compared with the prior art, the slot length is increased under the same size, and the size of the metasurface is reduced), and then improving the adaptability between the metasurface and the element antenna (the miniaturization of the anti-interference element antenna requires the miniaturization of the adapted metasurface design). By designing a multifunctional metasurface with band-pass characteristics (band-pass means that only specific frequencies can pass in the spatial wave direction, that is, improving the out-of-band anti-interference ability), the anti-out-of-band (heterogeneous frequency) interference ability of the Beidou anti-interference antenna array is improved.

[0042] Preferably, the depressions are arranged on the inner side of the closed-loop slot structure, and the protrusions are arranged on the outer side.

[0043] Preferably, the closed-loop slot structure is a quasi-square quadrilateral structure, and each side of the quasi-square quadrilateral structure includes protrusions and depressions.

[0044] Preferably, a depression is correspondingly arranged on the inner side of each protrusion in the closed-loop slot structure.

[0045] Preferably, in the periodically arranged cross-finger-like units in a single antenna element, the recess lengths of the cross-finger-like units in the same column or the same row are the same, and the recess lengths of the cross-finger-like units in different columns or different rows are different. Figure 7-8 An example is shown where the recess lengths of the cross-finger-like units in the same column in the periodically arranged cross-finger-like units in a single antenna element are the same, and the recess lengths of the cross-finger-like units in different columns are different.

[0046] Preferably, in combination with Figure 9-11 , the antenna element adopts a microstrip antenna solution and uses Rogers RO3210 board with a relative dielectric constant of about 10.2, including a dielectric substrate, a radiation patch, and a coaxial feeding probe. The bottom layer of the dielectric substrate is a printed copper foil, and the upper layer of the dielectric substrate is a radiation patch. The antenna element receives a right-handed circularly polarized wave through the coaxial feeding probe and converts the free-space wave into a guided wave. The external feeding interface of the antenna element uses a standard 50Ω coaxial line / connector.

[0047] Preferably, the number of the antenna elements is four, and the four antenna elements are rotationally arranged and printed on a whole PCB board.

[0048] The multifunctional metasurface is located above the antenna array and integrated with the top surface of the radome. FR4 board with a dielectric constant of about 4.4 is used as the supporting dielectric substrate. The multifunctional metasurface is printed on the upper layer of the FR4 dielectric substrate. The radome uses a conventional fiberglass material and is located on the outermost layer of the antenna array to play a role in protecting components. The radome and the multifunctional metasurface are compositely integrated, effectively reducing the structural size of the multifunctional metasurface while covering the metasurface printed circuit in the dielectric, improving the environmental adaptability (corrosion resistance) of the metasurface.

[0049] By printing the multifunctional metasurface structure on a single-sided PCB and changing the length dimension of the cross-finger-like slot structure, the transmission phase of the multifunctional metasurface can be effectively changed. By using a combination of multifunctional metasurfaces, a specific phase change can be achieved, thereby realizing the beam adjustment of the antenna elements and solving the problem of beam deflection of the antenna elements caused by factors such as the feeding structure and boundary asymmetry of the antenna elements. Figure 7 A schematic diagram of the 3*3 multifunctional metasurface cladding is given. Figure 8 For Figure 7 a schematic diagram showing that the slot structures of the three states become shorter from left to right in Figure 8 The recess lengths from left to right in are 1.2mm, 0.7mm, and 0.3mm respectively. Figure 13 It is a frequency on-off characteristic diagram of the metasurface in three states. The recess length of 0.3mm corresponds to the red line, 0.7mm corresponds to the green line, and 1.2mm corresponds to the blue line. All can pass through the frequencies near B3 of Beidou with low loss and play a certain blocking role for out-of-band frequencies. Figure 14It is the transmission amplitude curve graph of the multifunctional metasurface in three states. By controlling the length dimensions of the depressions and protrusions, the depression length at the center frequency of B3 is 1.2 mm to achieve a phase of -35°, 0.7 mm to achieve a phase of -9°, and 0.3 mm to achieve a phase of 18°. (The normalized phases are -26°, 0°, and 27° for an equal-phase arrangement to achieve beam pointing adjustment).

[0050] Figure 12 It is a schematic diagram of beam correction before and after adding a multifunctional metasurface to a single antenna element. The red color represents the case without the multifunctional metasurface structure, and the blue color represents the case after adding the multifunctional metasurface. The problem of pattern deflection caused by current asymmetry in the single-feed structure is significantly improved after adding a multifunctional metasurface with a specific phase arrangement.

[0051] Figure 15 It is a typical isolation degree change graph without adding a multifunctional metasurface and isolation posts; Figure 16 It is a typical isolation degree change graph after adding a multifunctional metasurface and isolation posts. It can be seen that the present invention can reduce the mutual coupling between the elements of the miniaturized Beidou anti-jamming antenna array and achieve an improvement in the isolation degree between the elements of the Beidou anti-jamming antenna array.

[0052] Figure 17 It is a comparison graph of the anti-jamming nulls of the antenna array at a typical angle azimuth of 0 and elevation of 10° before and after adding a multifunctional metasurface and isolation posts. Taking the center frequency of Beidou B3 as an example, the mutual coupling between elements is significantly reduced, and the isolation degree is increased by more than 15 dB. Taking the center frequency of Beidou B3 as an example, in the case of ideal anti-jamming amplitude and phase, the null is increased by about 5 dB after adding the multifunctional metasurface. Combining the improvement of the isolation degree between channels (signal-to-noise ratio improvement), the design of the multifunctional metasurface will greatly improve the anti-jamming performance of the Beidou anti-jamming antenna array.

[0053] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low mutual coupling Beidou antenna array, characterized in that: Including antenna arrays, multifunctional metasurfaces, and radomes; The multifunctional metasurface is located between the antenna array and the antenna cover. The antenna array includes multiple antenna elements and multiple metal grounding posts. The multiple metal grounding posts are arranged around the antenna elements using a PCB metallization via process. The multiple antenna elements are arranged and printed on a whole PCB board to form the antenna array; the multifunctional metasurface includes multiple periodically arranged quasi-interdigitated units, each of which includes a closed-loop gap structure opened on the PCB board, and the closed-loop gap structure includes multiple protrusions and recesses, and the protrusions and recesses are alternately arranged on the inner and outer sides of the closed-loop gap structure.

2. The low mutual coupling Beidou antenna array according to claim 1, characterized in that: The recess is arranged on the inner side of the closed-loop gap structure, and the protrusion is arranged on the outer side.

3. The low mutual coupling Beidou antenna array according to claim 2, characterized in that: The closed-loop gap structure is a quadrilateral structure, and each side of the quadrilateral structure includes a protrusion and a recess.

4. The low mutual coupling Beidou antenna array according to claim 3, characterized in that: Each of the protrusions is correspondingly provided with a recess on the inner side of the closed-loop gap structure.

5. The low mutual coupling Beidou antenna array according to claim 3, characterized in that: Among the periodically arranged quasi-interdigital units in a single antenna array element, the quasi-interdigital units in the same column or row have the same concave length, and the quasi-interdigital units in different columns or rows have different concave lengths.

6. The low mutual coupling Beidou antenna array according to any one of claims 1 to 5, characterized in that: The length of the closed loop gap structure of the quasi-interdigitated unit is one quarter of the medium wavelength.

7. The low mutual coupling Beidou antenna array according to claim 6, characterized in that: The antenna array element comprises a dielectric substrate, a radiation patch, and a coaxial feeding probe. The bottom layer of the dielectric substrate is a printed copper sheet, and the upper layer of the dielectric substrate is a radiation patch. The antenna array element receives right-hand circularly polarized waves through the coaxial feeding probe to convert free space waves into guided waves.

8. The low mutual coupling Beidou antenna array according to claim 7, characterized in that: The antenna array element adopts a cut-angle single-fed microstrip antenna design, and realizes the right-hand circular polarization characteristic of the array element through cut-angle perturbation.

9. The low mutual coupling Beidou antenna array according to claim 8, characterized in that: The number of the antenna array elements is four, and the four antenna array elements are rotated and arranged and printed on a whole PCB board.

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