A broadband circularly polarized integrated feed transmissive array antenna covering the entire Ka band

Abstract

This invention discloses a broadband circularly polarized integrated feed transmission array antenna covering the entire Ka-band, comprising an array surface and an integrated feed. The phase center of the integrated feed coincides with the focal point of the array surface, illuminating the array surface perpendicularly and forming a 45-degree angle with the array surface in the horizontal direction. The array surface comprises multiple array elements of different sizes arranged linearly. Each array element includes two orthogonally arranged first and second dielectric substrates, which have the same height but different thicknesses. The integrated feed comprises a stacked first and second PCB board. A substrate integrated waveguide is disposed on the first PCB board with coupling slots, and a substrate integrated waveguide cavity and annular metal patches surrounding the substrate integrated waveguide cavity are disposed on the second PCB board. This invention achieves a wide axial ratio bandwidth and gain bandwidth, and has the advantages of low profile, light weight, easy fabrication, and low cost.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a broadband circularly polarized integrated feed transmission array antenna covering the entire Ka band. Background Technology

[0002] In recent years, 5G millimeter-wave communication has attracted widespread attention from academia and industry due to its advantages such as high speed, low latency, and massive connectivity. Compared to microwave communication, the increased operating frequency leads to higher losses in electromagnetic wave propagation through the air, thus requiring millimeter-wave antennas to possess high gain. Simultaneously, the increased frequency results in smaller antenna dimensions, increasing the difficulty of antenna fabrication, especially for antenna arrays involving complex feeding networks, significantly increasing both design and manufacturing complexity. Transmissive array antennas undoubtedly offer a good solution to these problems. Their feeding method is space-based, eliminating the need for complex feeding networks, thus reducing design and manufacturing complexity while offering low feeding losses. Furthermore, because their operating principle is similar to that of prism antennas, they naturally possess high gain characteristics.

[0003] Currently, research on transmission array antennas still has some aspects that need improvement. First, regarding polarization, research on circularly polarized transmission array antennas is relatively limited, and the reported designs generally suffer from narrow bandwidth, primarily in terms of axial ratio bandwidth and gain bandwidth. The axial ratio bandwidth in currently reported designs typically does not exceed 25%, and the 3-dB gain bandwidth is even narrower (C. Tian, ​​Y. Jiao and G. Zhao, "Circularly polarized transmitter array antenna using low-profile dual-linearly polarized elements," IEEE An tennas Wireless Propag. Lett., vol. 16, pp. 465-468, 2017). Second, traditional transmission array antennas generally use horn antennas as feed sources; however, horn antennas generally suffer from drawbacks such as large size, heavy weight, high manufacturing difficulty, and high cost, which are very unfavorable for practical engineering applications. Summary of the Invention

[0004] To address the problems of narrow axial ratio and gain bandwidth in traditional circularly polarized transmission array antennas, as well as the large size, heavy weight, high manufacturing difficulty, and high cost of the feed section in traditional circularly polarized transmission array antennas, this invention proposes a broadband circularly polarized integrated feed transmission array antenna covering the entire Ka-band. The array element adopts a cross-shaped dielectric transmission line as the basic unit structure, which can ensure the stability of phase shift of the array element in the broadband range, thereby achieving a wider axial ratio and gain bandwidth. The integrated feed replaces the traditional horn feed, and its operating bandwidth can be matched with the broadband array. It has the advantages of low profile, light weight, easy manufacturing, and low cost.

[0005] To achieve the objective of this invention, a broadband circularly polarized integrated feed transmission array antenna covering the entire Ka-band is provided, comprising an array surface and an integrated feed. The phase center of the integrated feed coincides with the focal point of the array surface, perpendicularly illuminating the array surface and forming a 45-degree angle with the array surface in the horizontal direction, wherein:

[0006] The array consists of multiple array elements of different sizes arranged in a linear form. Each array element includes two orthogonally arranged first and second dielectric plates. The first and second dielectric plates have the same height but different thicknesses.

[0007] The integrated feed includes a stacked first PCB board and a second PCB board. The first PCB board is provided with a substrate integrated waveguide and has a coupling slot. The second PCB board is provided with a substrate integrated waveguide cavity and an annular metal patch disposed around the substrate integrated waveguide cavity.

[0008] Furthermore, it also includes an adapter for powering the integrated feed.

[0009] Furthermore, the thicknesses W1 and W2 of the first and second dielectric substrates must be selected according to Fermat's principle and the principle of circularly polarized radiation, wherein:

[0010] According to Fermat's principle, the electromagnetic wave radiated by the integrated feed must have a plane wavefront after passing through the array. Therefore, the required phase shift for each array element is:

[0011]

[0012] In the formula, x and y represent the coordinates of a point on the array surface in the x and y directions, f represents the focal length of the array surface, and λ represents the free-space wavelength. Indicates any initial phase; Let represent the phase shift at point (x, y). There are two orthogonal electric field modes within a single element of the array, and their phase shifts within the element can be expressed as follows: and To satisfy Fermat's principle, we need to let or One of the two equals

[0013] To satisfy the principle of circular polarization radiation, and Simultaneously satisfy

[0014] The thicknesses W1 and W2 that satisfy the above two conditions can be obtained by using full-wave simulation software to perform parameter scanning.

[0015] Furthermore, the array surface is integrally formed using 3D printing technology.

[0016] Furthermore, the coupling slot is located at the short-circuit end of the waveguide.

[0017] Furthermore, the substrate-integrated waveguide cavity is rectangular.

[0018] Furthermore, adjusting the thickness parameter of the dielectric substrate in each array element can change the phase shift magnitude of the corresponding component within each array element.

[0019] Furthermore, the annular metal patch is a rectangular ring.

[0020] Compared with the prior art, the present invention can achieve at least the following beneficial effects:

[0021] This invention achieves a broadband transmission array design by employing a cross-shaped dielectric substrate unit structure and utilizing the true time delay characteristics of dielectric transmission lines. Simultaneously, based on substrate integrated waveguide technology, a broadband integrated feed design is proposed. Compared to traditional horn feeds, the integrated feed offers advantages such as low profile, light weight, ease of fabrication, and low cost. In terms of performance, this invention features broadband coverage (covering the entire Ka-band), high gain, and stable performance within the operating frequency band. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0023] Figure 1 This is a schematic diagram of the structure of a broadband circularly polarized integrated feed transmission array antenna covering the entire Ka band, provided by an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the array element in an embodiment of the present invention.

[0025] Figure 3This is a schematic diagram of the integrated feed source in an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of the structure of the first PCB board in the integrated feed source of this invention.

[0027] Figure 5 This is a schematic diagram of the structure of the second PCB board in the integrated feed source of this invention.

[0028] Figure 6 This is a schematic diagram showing the relationship between the S-parameters and frequency of the integrated feed in an embodiment of the present invention.

[0029] Figure 7 This is a schematic diagram of the gain performance of the integrated feed source in an embodiment of the present invention.

[0030] Figure 8 This is the radiation pattern of the integrated feed at the center frequencies of the E-plane and H-plane in this embodiment of the invention.

[0031] Figure 9 This is a schematic diagram showing the relationship between the S-parameters and frequency of the transmission array antenna in an embodiment of the present invention.

[0032] Figure 10 This is a schematic diagram of the axial ratio performance of the transmission array antenna in an embodiment of the present invention.

[0033] Figure 11 This is a schematic diagram of the gain performance of the transmission array antenna in an embodiment of the present invention.

[0034] Figure 12 This is the radiation pattern of the transmission array antenna in the embodiment of the present invention at the center frequencies of the E-plane and H-plane. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Furthermore, in this invention, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the invention. They are merely used to distinguish components or operations described using the same technical terms, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If a combination of technical solutions is contradictory or impossible to implement, such a combination should be considered nonexistent and not within the scope of protection claimed by this invention.

[0037] This invention provides a broadband circularly polarized integrated feed transmission array antenna covering the entire Ka-band, such as... Figure 1 As shown, the antenna includes an array 11 and an integrated feed 13. The phase center of the integrated feed 13 coincides with the focal point of the array 11, illuminating the array 11 perpendicularly, and forming a 45-degree angle with the array 11 in the horizontal direction. The integrated feed 13 is fed by an adapter 14. The establishment of the rectangular coordinate system is as follows: Figures 1 to 5 As shown, the coordinate system xy plane is parallel to the array surface 11, the x-axis and y-axis are parallel to the two sides of the array surface 11 respectively, and the z-axis points in the direction in which the electromagnetic wave is perpendicularly incident on the array surface.

[0038] In some embodiments of the present invention, the adapter 14 is a conversion structure between a standard waveguide and a substrate integrated waveguide.

[0039] The array 11 comprises multiple array elements 12 of different sizes arranged in a linear fashion. (See also...) Figure 2 Each array element 12 includes two orthogonally placed first dielectric plates 21 and second dielectric plates 22. They have the same height, H, but different thicknesses, W1 and W2, respectively.

[0040] The height H of each element can be an empirical value, generally three free-space wavelengths. The thicknesses W1 and W2 of the first dielectric substrate 21 and the second dielectric substrate 22 must be selected according to: 1) Fermat's principle; 2) the principle of circularly polarized radiation. First, according to Fermat's principle, the electromagnetic wave radiated by the integrated feed 13 must have a plane wavefront after passing through the array 11. Therefore, the required phase shift for each array element 12 is:

[0041]

[0042] Where x and y represent the coordinates of a point on array 11 in the x and y directions, f represents the focal length of array 11, and λ represents the free-space wavelength. Indicates any initial phase; This represents the phase shift magnitude at point (x, y), which is the phase shift magnitude required for each array element 12. There are two orthogonal electric field modes within the array element 12, and their phase shift magnitudes within the element can be expressed as follows: and To satisfy Fermat's principle, we need to let or One of the two equals On the other hand, in order to satisfy the principle of circular polarization radiation, these two phases must also simultaneously satisfy the following equation:

[0043]

[0044] By using the full-wave simulation software Ansys HFSS to perform a parameter scan, W1 and W2 that satisfy the above two conditions can be obtained.

[0045] In some embodiments of the present invention, the array surface 11 is integrally formed using 3D printing technology, and the dielectric material has a relative permittivity of 2.9 and a loss tangent of 0.01.

[0046] The integrated feed 13 has a double-layer PCB structure, including a stacked first PCB 32 and a second PCB 33, and is powered by port 31, such as... Figure 3 As shown. A substrate integrated waveguide is disposed on the first PCB board 32, and a coupling slot 41 is opened at the short-circuit end of the waveguide, as shown. Figure 4 As shown. A rectangular substrate integrated waveguide cavity 52 is provided on the second PCB board 33, and annular metal patches 51 are provided around the substrate integrated waveguide cavity 52, as shown. Figure 5 As shown. The coupling slot 41 couples electromagnetic waves into the substrate integrated waveguide cavity 52, where they are radiated. The beamwidth of the feed can be adjusted by changing the ring width of the annular metal patch 51.

[0047] In some embodiments of the present invention, the thicknesses of the first PCB board 32 and the second PCB board 33 are 1.295 mm and 1.575 mm, respectively. The dielectric constant of the substrate material is 2.2, and the loss tangent is 0.0009.

[0048] When the integrated feed transmission array antenna provided in the aforementioned embodiment is in operation, the electromagnetic signal is fed into the integrated feed 13 through the adapter 14, and then the integrated feed 13 generates a 45-degree linearly polarized electromagnetic wave that is incident on the array surface 11. This linearly polarized wave can be decomposed into two orthogonal, equal-amplitude, in-phase components. Since the first dielectric plate 21 and the second dielectric plate 22 in the array element 12 have different thicknesses, the array element 12 can be regarded as an anisotropic structure, which allows the two components of the incident wave to have different phase constants during propagation. After a certain propagation distance, the phase difference between the two components of the incident wave can reach 90 degrees, thereby achieving circularly polarized radiation. Similarly, by adjusting the thickness parameter of the dielectric plate in each array element 12, the phase shift of the corresponding component in each array element 12 can be changed, so that the electromagnetic wave satisfies Fermat's principle when emitted, achieving focused beam.

[0049] In some embodiments of the present invention, a commonly used 3-bit scheme is employed to quantize the required phase shift size for each cell in the array 11, that is, to discretize 0-360° into eight phases: 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, and to design eight different cell sizes accordingly. The thicknesses W1 and W2 of the first dielectric substrate 21 and the second dielectric substrate 22 in these cells are shown in Table 1.

[0050]

[0051]

[0052] Figures 6 to 8 The figures shown illustrate the performance results of the integrated feed 13 in this embodiment of the invention. This integrated feed 13 can achieve impedance matching below -10dB in a frequency band ranging from 26.5GHz to 40GHz, such as... Figure 6 As shown, the impedance bandwidth is greater than 40.6%, indicating a wide operating bandwidth. Figure 7 The figure shows the gain performance of the integrated feed 13 in this embodiment of the invention. The average gain is 9.2dB within the impedance bandwidth (26.5-40GHz), and the gain fluctuation is ±0.75dB, indicating that the integrated feed 13 has stable radiation performance. Figure 8 The diagram shown is the radiation pattern of the integrated feed 13 at the center frequency in an embodiment of the present invention. It can be seen that the integrated feed 13 has a low cross-polarization level and good unidirectional radiation performance.

[0053] Figures 9 to 12 The figures show the performance results of the transmission array antenna in the entire embodiment of the present invention. Figure 9The impedance bandwidth of the transmission array antenna is shown. This antenna achieves impedance matching below -10dB within the 26.5GHz to 40GHz frequency range, indicating that it has a wide impedance bandwidth. Axial ratio performance is as follows... Figure 10 As shown, the axial ratio is less than 3dB and the axial ratio bandwidth is greater than 40.6% in the frequency band from 26.5GHz to 40GHz, covering the entire Ka band, which is far higher than the current technical level. Gain characteristics are as follows... Figure 11 As shown, within the operating frequency band (26.5GHz-40GHz), the maximum gain is 22.8dBic, and the gain fluctuation is less than 3dB, indicating that the antenna has stable gain performance within the band, and the 3-dB gain bandwidth can also cover the entire Ka band. Figure 12 The radiation pattern at the center frequency shows that the antenna sidelobes are below -15dB, indicating that this transmission array antenna can achieve beam focusing and has low sidelobes. In summary, this antenna has the advantages of wide bandwidth, high gain, and stable radiation performance within its operating frequency band.

[0054] The broadband circularly polarized integrated feed projection array antenna covering the entire Ka band provided in the foregoing embodiments of this invention uses cross-shaped dielectric transmission lines as the basic unit structure for its array elements. Since the dielectric transmission lines have true time delay characteristics, the phase shift stability of the array elements can be guaranteed within the broadband range, thereby achieving a wider axial ratio bandwidth and gain bandwidth. Secondly, this invention proposes a broadband planar feed whose operating bandwidth can match that of the broadband array, replacing traditional horn feeds and offering advantages such as low profile, light weight, ease of fabrication, and low cost. Furthermore, according to the 5G millimeter-wave frequency bands defined by the 3GPP organization, bands such as n257, n260, and n261 are all located within the Ka band; therefore, operating bandwidth covering the entire Ka band increases the flexibility of the antenna in practical applications.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A broadband circularly polarized integrated feed transmission array antenna covering the entire Ka band, comprising an array surface (11) and an integrated feed (13), wherein the phase center of the integrated feed (13) coincides with the focal point of the array surface (11), vertically illuminating the array surface (11), and forming a 45-degree angle with the array surface (11) in the horizontal direction, characterized in that: The array (11) includes multiple array elements (12) of different sizes arranged in a linear form. Each array element (12) includes two orthogonally arranged first dielectric plates (21) and second dielectric plates (22). The first dielectric plates (21) and second dielectric plates (22) have the same height but different thicknesses. The thicknesses W1 and W2 must be selected to satisfy both Fermat's principle and the principle of circular polarization radiation. The phase shift of the two orthogonal electric field modes in each array element (12) is... and Simultaneously satisfy ; The integrated feed (13) includes a stacked first PCB board (32) and a second PCB board (33). The first PCB board (32) is provided with a substrate integrated waveguide and has a coupling slot (41). The second PCB board (33) is provided with a rectangular substrate integrated waveguide cavity (52) and an annular metal patch (51) disposed around the substrate integrated waveguide cavity (52). The annular metal patch (51) is a rectangular ring. The antenna operates in the full Ka band: 26.5 GHz–40 GHz, with an axial ratio bandwidth greater than 40.6%, and a 3-dB gain bandwidth covering the entire Ka band.

2. The broadband circularly polarized integrated feed transmission array antenna covering the entire Ka-band according to claim 1, characterized in that, It also includes an adapter (14) for powering the integrated feed (13).

3. A broadband circularly polarized integrated feed transmission array antenna covering the entire Ka-band as described in claim 1, characterized in that, The thicknesses W1 and W2 of the first dielectric plate (21) and the second dielectric plate (22) must be selected according to Fermat's principle and the principle of circularly polarized radiation. According to Fermat's principle, the electromagnetic wave radiated by the integrated feed (13) must have a plane wavefront after passing through the array (11). Therefore, the phase shift required for each array element (12) is: In the formula, and This represents the coordinates of a point on the array (11) in the x and y directions. Let λ represent the focal length of the array (11) and λ represent the wavelength in free space. Indicates any initial phase; Point The phase shift magnitude at the point is given by the fact that there are two orthogonal electric field modes within the array element (12), and their phase shift magnitudes within the element are expressed as follows: and , or One of the two equals ; To satisfy the principle of circular polarization radiation, and Simultaneously satisfy ; The thicknesses W1 and W2 that satisfy the above two conditions can be obtained by using full-wave simulation software to perform parameter scanning.

4. A broadband circularly polarized integrated feed transmission array antenna covering the entire Ka-band as described in claim 1, characterized in that, The array (11) is formed in one piece using 3D printing technology.

5. A broadband circularly polarized integrated feed transmission array antenna covering the entire Ka-band according to claim 1, characterized in that, The coupling slot (41) is located at the short-circuit end of the waveguide.

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