Low profile dual circularly polarized ka-band phased array antenna

Abstract

This invention discloses a low-profile, dual-circularly polarized Ka-band phased array antenna, primarily addressing the problems of high profile, complex structure, and inability to polarize multiplex traditional circularly polarized phased array antennas. The antenna feeding structure and metal patch structure of this invention are symmetrical. The left and right circularly polarized feed ports are directly connected to the radiating patch, respectively exciting the patch to generate left-hand and right-hand circular polarization, achieving control from single to dual circular polarization. The direct connection of the left and right circularly polarized feed ports to the radiating patch excites the patch to generate left-hand and right-hand circular polarization without introducing any additional structures, simplifying the antenna design process and enabling polarization multiplexing of the circularly polarized antenna. The antenna of this invention consists of two dielectric substrates, eliminating the need for a complex intermediate feed network, resulting in an antenna with advantages of simple structure and low profile.

Description

Technical Field

[0001] This invention belongs to the field of radar communication technology, and more specifically relates to a low-profile, dual-circularly polarized Ka-band phased array antenna in the field of antenna technology. This invention can be used for millimeter-wave antenna communication and high-resolution radar imaging. Background Technology

[0002] In radio communication systems such as satellite positioning, radar detection, and electronic countermeasures, to quickly and accurately acquire weak signals transmitted by satellites, the system's antennas are generally required to have a wide beamwidth and achieve wide-angle circular polarization coverage. Therefore, the application of circularly polarized phased array antennas, which meet these engineering requirements, is becoming increasingly widespread. The polarization mode of circularly polarized phased array antennas can suppress multipath attenuation, reduce system complexity, and solve the shortcomings of linear polarization, such as channel fading and insufficient channel capacity. Dual-circularly polarized array antennas, which can simultaneously achieve left-hand and right-hand circular polarization radiation, have laid the foundation for the multi-functional application of phased arrays. Existing technologies include many wide-bandwidth, wide-angle circularly polarized phased array forms, such as four-arm helical antennas. From the structure of these antennas, their radiation modes can be used to widen the antenna beamwidth. However, these antennas have a high profile and require strict manufacturing processes, thus reducing the antenna's profile height is technically necessary. Traditional microstrip antennas are widely used in phased arrays due to their advantages such as small size, easy conformal integration with the carrier, easy circular polarization, and low profile. However, microstrip antennas are high-Q resonant antennas with narrow bandwidth. Therefore, improving the bandwidth and wide-angle scanning capability of circularly polarized patch antennas has become one of the urgent problems to be solved in circularly polarized phased array antenna technology. Most current circularly polarized phased arrays are single-circularly polarized. The implementation of some dual-circularly polarized phased arrays requires a four-port network loaded with linear polarization, using the characteristics of a microstrip bridge to switch between the two circular polarizations, which increases the complexity and profile height of the antenna structure. In summary, existing circularly polarized phased array antennas have the following problems: high profile; small operating bandwidth; small beamwidth; and mostly single-circular polarization, unable to reuse polarization.

[0003] Chengdu Weixun Technology Co., Ltd. disclosed a Ka dual-circular polarization antenna element and a planar array antenna in its patent application "A Ka Dual-Circular Polarization Antenna Element and Planar Array Antenna" (Application No. 202310399656.4, Publication No. CN 116231330A). The antenna consists of a radiating patch layer, a slot coupling layer, a waveguide transmission layer, and a feed network layer arranged sequentially from top to bottom. The radiating patch layer has several microstrip line structures, including a first microstrip line and a second microstrip line, which form a 90° phase difference between the orthogonal components of the electric field. The slot coupling layer includes a second substrate with corresponding recesses for the microstrip line structures. The slot coupling layer and the radiating patch layer undergo relative displacement under external force, allowing the microstrip line structure corresponding to the recesses to switch between left-hand circular polarization and right-hand circular polarization. However, this antenna still has two shortcomings: First, it requires relative displacement under the action of external force to adjust circular polarization, which is less flexible and prone to causing wear. Second, the antenna has a high profile and complex structure; the two-layer microstrip structure increases the antenna's height and design complexity, raising its cost and manufacturing difficulty.

[0004] Xi'an University of Electronic Science and Technology disclosed a spaceborne Ka-band circularly polarized antenna element and its corresponding phased array antenna in its patent application "A Spaceborne Ka-band Circularly Polarized Antenna Element, Antenna Array and Phased Array" (application number 202211486446.0, publication number CN 115810917 A). The phased array antenna includes an upper radiating structure, a middle parasitic structure, and a lower feeding structure. The radiating structure consists of an upper metal patch, enabling left-hand circularly polarized beam radiation. The feed is provided by the bottom metal probe, which is coupled to the upper metal layer for radiation. A ring of metallized vias is added around the radiating antenna to reduce coupling between antennas. This phased array can achieve left-hand circular polarization and ±55° wide-angle scanning. However, the antenna still has two shortcomings: firstly, the bottom metal probe feed is coupled to the upper metal layer for left-hand circular polarization radiation, making it a single-circular-polarized phased array, unable to achieve dual-circular polarization. Secondly, the antenna has a four-layer structure, which increases the complexity of the antenna design, as well as the cost and manufacturing difficulty. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by proposing a low-profile dual-circularly polarized Ka-band phased array antenna, which aims to solve the problems of high profile, complex structure, and inability to polarize multiplex traditional circularly polarized phased array antennas.

[0006] The technical approach to achieving the objective of this invention is as follows: Addressing the aforementioned problems, the Ka-band phased array antenna of this invention employs a two-layer dielectric substrate structure: an upper parasitic metal patch, a middle metal radiating structure, and a lower feed structure. The feed is provided by the bottom metal probe, which is coupled to the upper metal layer for radiation. Left-hand circularly polarized beam radiation is generated under the excitation of the left-hand circularly polarized port, and right-hand circularly polarized beam radiation is generated under the excitation of the right-hand circularly polarized port. To reduce coupling between antennas, a ring of metallized vias is added around the radiating antenna. By symmetrically designing the port positions and patch shapes, the antenna feed structure and the metal patch structure are symmetrical. The two ports respectively excite the radiating patch to generate left-hand and right-hand circularly polarized radiation, eliminating the need for a complex feed network layer design. Polarization multiplexing of left-hand and right-hand circularly polarized radiation is achieved by directly connecting the left-hand and right-hand circularly polarized feed ports to the radiating patch. The Ka-band phased array achieves dual circular polarization without introducing additional structures, simplifying the antenna design process and solving the design problem that most existing circularly polarized phased array antennas can only achieve single circular polarization and cannot reuse polarization. The antenna consists of two dielectric substrates, eliminating the need for microstrip networks to achieve circular polarization, thus reducing the antenna profile. Polarization switching can be achieved by controlling the feeding mode through the phased array's T / R components, solving the problems of high profile, complex structure, and high manufacturing cost associated with phased array antennas.

[0007] The Ka-band phased array antenna of the present invention comprises N×N antenna arrays arranged in a rectangular shape, each antenna array consisting of 4×4 Ka-band dual circular polarization antenna subarrays, wherein N is an integer greater than or equal to 2; the antenna elements in each antenna subarray are composed of two layers of dielectric substrate, the feeding structure and the metal patch structure are symmetrical, and the left and right circular polarization feeding structures are directly connected to the metal patch structure.

[0008] Furthermore, each antenna subarray consists of four Ka-band dual-circularly polarized antenna elements, arranged in a 90° rotational pattern with the first antenna element as the reference point. A feeding transmission structure is installed below each antenna subarray.

[0009] Furthermore, each power supply transmission structure includes four left-hand circular polarization ports and four right-hand circular polarization ports, with the left-hand and right-hand circular polarization ports arranged in a cross pattern, and each port connected to one phase shifter.

[0010] Furthermore, the rotation angle of the Ka-band dual circularly polarized antenna element is equal to the phase of the phase shifter connected to its corresponding port; when operating at the left-hand circularly polarized port, the rotation angles and phases of the four Ka-band dual circularly polarized antenna elements are 0°, 90°, 180°, and 270°, respectively; when operating at the right-hand circularly polarized port, the rotation angles and phases of the four Ka-band dual circularly polarized antenna elements are 0°, 270°, 180°, and 90°, respectively.

[0011] Furthermore, each antenna element in the antenna subarray consists of two dielectric substrates: a lower dielectric substrate, a middle prepreg layer, and an upper dielectric substrate arranged sequentially from bottom to top. The lower dielectric substrate has mirror-symmetrical left- and right-hand circular polarization feeding structures at its ports, including a first metallized blind via and a second metallized blind via, penetrating the lower dielectric substrate. Left-hand circular polarization is achieved when fed through the first metallized blind via, and right-hand circular polarization is achieved when fed through the second metallized blind via. Metallized vias are provided in the lower dielectric substrate, the middle prepreg layer, and the upper dielectric substrate, penetrating all three layers. These metallized vias are distributed in multiple equally spaced configurations.

[0012] Furthermore, the horizontal cross-sections of the lower dielectric substrate, the intermediate semi-cured layer, and the upper dielectric substrate are regular quadrilaterals, and their areas are equal.

[0013] Furthermore, the sum of the height of the lower dielectric substrate, the height of the intermediate semi-cured layer, and the height of the upper dielectric substrate is less than 2 mm.

[0014] Furthermore, a first upper metal ring and a first upper metal patch are printed on the upper surface of the lower dielectric substrate, and the two metal patches have symmetrical structures. The metal patches are located within the first upper metal ring and are isolated from each other. A second upper metal ring and a second upper metal patch are printed on the upper surface of the upper dielectric substrate, and the two metal patches have symmetrical structures. The second upper metal patch is located within the second upper metal ring and is isolated from each other. Both the first and second upper metal rings are closed quadrilateral frames and are connected through metallized vias.

[0015] Further, the first upper metal patch is composed of a first part, a second part, a third part, and a fourth part. The first and second parts are both arrow-shaped, symmetrically arranged with the arrows pointing away from the center of the first dielectric substrate, and connected at their tails. The width of the connection point is less than the width of the widest part of the arrow. The third and fourth parts are each composed of a rectangle and a semicircular ring. One side of the rectangle is connected to the arrow side of the first part, and the other side is connected to the semicircular ring. The fourth part is symmetrically arranged with the third part. The second upper metal patch is composed of the first and second parts. The first part is an octagon with a hollowed-out center, and the second part is a standard square located in the hollowed-out center of the first part.

[0016] Furthermore, the first upper metal patch is fed through the metallized blind via of the feeding structure, and the second upper metal patch is coupled to the first upper metal patch for radiation. When fed through the first metallized blind via, left-hand circular polarization is achieved, and when fed through the second metallized blind via, right-hand circular polarization is achieved, thus realizing polarization multiplexing.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] First, the antenna of this invention features a symmetrical design of port positions and patch morphology. The antenna feed structure and metal patch structure are symmetrical, with left-hand and right-hand circular polarization feed ports directly connected to the radiating patch, respectively exciting the patch to generate left-hand and right-hand circular polarization. This achieves control from single-circular polarization to dual-circular polarization, overcoming the limitation of existing technologies that can only achieve single-circular polarization and struggle to achieve polarization multiplexing. This invention avoids complex feed network layers, achieving polarization multiplexing of left-hand and right-hand circular polarization by directly connecting the left-hand and right-hand circular polarization feed ports to the radiating patch. The Ka-band phased array achieves dual-circular polarization without introducing any additional structures, simplifying the antenna design process.

[0019] Secondly, the antenna of the present invention is composed of two dielectric substrates, which eliminates the need for the design of a complex feed network layer. This solves the problem of high feed network design complexity and increased antenna profile height. It does not require an intermediate feed network, and polarization switching can be achieved directly by controlling the feed mode through the T / R component of the phased array. This gives the antenna of the present invention the advantages of simple structure and low profile. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a Ka-band dual circularly polarized phased array antenna according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of a Ka-band dual circularly polarized antenna subarray according to an embodiment of the present invention; wherein, Figure 2 (a) is a diagram of the overall structure of the antenna subarray; Figure 2 (b) is a schematic diagram of the left and right rotation ports of the antenna subarray;

[0022] Figure 3 This is a schematic diagram of the Ka-band dual circularly polarized antenna element of the present invention; wherein, Figure 3 (a) is a schematic diagram of the overall structure of the antenna unit; Figure 3 (b) is a side view of the antenna element; Figure 3 (c) is a horizontal schematic diagram of the upper surface of the first dielectric substrate of the antenna element; Figure 3 (d) is a horizontal schematic diagram of the upper surface of the second dielectric substrate of the antenna element;

[0023] Figure 4The image shows the simulation results of a Ka-band dual-circularly polarized antenna element; among them, Figure 4 (a) is the VSWR diagram of a Ka-band dual circularly polarized antenna element; Figure 4 (b) is the axial ratio diagram of the Ka-band dual circularly polarized antenna element; Figure 4 (c) is the radiation pattern of the Ka-band dual circularly polarized antenna element at 29.3 GHz;

[0024] Figure 5 The axial ratio diagram of the Ka-band dual circularly polarized antenna subarray;

[0025] Figure 6 The image shows the simulation results of a Ka-band dual-circularly polarized phased array antenna; among them, Figure 6 (a) is the radiation pattern of the antenna array at 0° at 29.3 GHz; Figure 6 (b) is the axial ratio diagram of the antenna array at 0° at 29.3 GHz; Figure 6 (c) is the radiation pattern of the antenna array at 29.3 GHz and 60°. Figure 6 (d) is the axial ratio diagram of the antenna array at 29.3 GHz and 60°. Detailed Implementation

[0026] The embodiments and effects of the present invention will be further described below with reference to the accompanying drawings.

[0027] The antenna of this invention is a dual-circularly polarized phased array antenna operating in the millimeter-wave band. The number N of Ka-band dual-circularly polarized radiating elements is determined by the actual usage of the antenna. The dual-circularly polarized phased array antenna in this embodiment uses 8×8 Ka-band dual-circularly polarized antenna radiating elements. However, those skilled in the art should understand that millimeter-wave dual-circularly polarized phased array antennas can also be combined with other numbers of dual-circularly polarized antenna elements. For example, 2×2, 4×4, 6×6, 8×8, etc. This embodiment of the invention does not limit this.

[0028] Reference Figure 1 The Ka-band dual circularly polarized phased array antenna structure of the present invention will be further described below.

[0029] The dual-circularly polarized phased array antenna of this invention employs 64 Ka-band dual-circularly polarized antenna radiating elements, arranged in 4×4 Ka-band dual-circularly polarized antenna subarrays, according to... Figure 1 The pattern shown is arranged in a rectangular array, forming a 64-element Ka-band dual circularly polarized phased array. Figure 1 The black box with arrows in the middle indicates a Ka-band dual circularly polarized antenna subarray.

[0030] Reference Figure 2 The following is a further description of a subarray structure of the Ka-band dual circularly polarized antenna according to an embodiment of the present invention.

[0031] Each antenna subarray 1 consists of four Ka-band dual circularly polarized antenna elements 11, 12, 13, and 14, arranged in a 90° rotational array with antenna element 11 as the reference point. A feeding transmission structure 2 is provided below each antenna subarray, such as... Figure 2 As shown in (a).

[0032] The feed transmission structure 2 beneath each antenna subarray consists of four left-hand circularly polarized ports 201 and four right-hand circularly polarized ports 202. The left-hand and right-hand circularly polarized ports are arranged in a cross configuration, and each port is connected to a phase shifter, such as... Figure 2 As shown in (b).

[0033] In the aforementioned Ka-band dual circularly polarized antenna subarray, the rotation angle of each antenna element is equal to the phase of the phase shifter connected to its corresponding port. When the left-hand circularly polarized port 201 is operating, the rotation angles and phases of antenna elements 11, 12, 13, and 14 are 0°, 90°, 180°, and 270°, respectively. When the right-hand circularly polarized port 202 is operating, the rotation angles and phases of antenna elements 11, 12, 13, and 14 are 0°, 270°, 180°, and 90°, respectively. This phase setting causes the cross-polarization component generated by antenna element 11 to cancel out the cross-polarization components coupled to antenna elements 12 and 14, and the cross-polarization component generated by antenna element 12 to cancel out the cross-polarization component coupled to antenna element 13, and the cross-polarization component generated by antenna element 13 to cancel out the cross-polarization component coupled to antenna element 14. Therefore, the 90° sequential rotation array arrangement in the embodiments of the present invention can enable the antenna to obtain better main polarization components when operating in left-hand circular polarization or right-hand circular polarization.

[0034] refer to Figure 3 The structure of the Ka-band dual circularly polarized antenna element in this embodiment of the invention will be further described below.

[0035] The antenna element in each antenna subarray is composed of two dielectric substrates, meaning that from bottom to top, a blue lower dielectric substrate 6 with a height of h1 = 0.508 mm, an intermediate semi-cured layer 7 with a height of h2 = 0.1 mm, and a blue upper dielectric substrate 8 with a height of h3 = 1.016 mm are arranged sequentially. Figure 3 (a) and Figure 3 (b) is indicated by the black arrow.

[0036] Figure 3 In (a), the lower dielectric substrate 6 has a mirror-symmetrical left- and right-hand circular polarization feeding structure at the port position. Metallized blind vias 3 and 4 penetrate the lower dielectric substrate 6. When feeding through the metallized blind via 3, left-hand circular polarization is achieved; when feeding through the metallized blind via 4, right-hand circular polarization is achieved. Figure 3(a) Figure 3 (b) The red short column in the middle Figure 3 (c) shows the red dots with radius r1 = 0.1 mm.

[0037] Metallized vias 5 are provided in the lower dielectric substrate 6, the intermediate semi-cured layer 7, and the upper dielectric substrate 8, penetrating the upper substrate 8, the intermediate semi-cured layer 7, and the lower dielectric substrate 6. Multiple metallized vias 5 are distributed at equal intervals of l2 = 0.43 mm, which can reduce the coupling between antenna elements during array arrangement. Figure 3 (a) and Figure 3 (b) The red column in the middle Figure 3 (c) and Figure 3 (d) shows the pink dot with r0 of 0.1 mm.

[0038] The horizontal cross-sections of the lower dielectric substrate 6, the intermediate semi-cured layer 7, and the upper dielectric substrate 8 are regular quadrilaterals with side length l0 = 4.85 mm, and their areas are equal.

[0039] The sum of the height of the lower dielectric substrate 6, the height of the intermediate semi-cured layer 7, and the height of the upper dielectric substrate 8 is less than 2 mm.

[0040] The Ka-band dual circularly polarized antenna unit has a first upper metal ring 611 and a first upper metal patch 612 printed on the upper surface of the dielectric substrate 6. The two metal patches are symmetrically structured. The first upper metal patch 612 is located within the first upper metal ring 611 and is isolated from it, as shown below. Figure 3 (c) As shown in the pink symmetrical structure and pink box. A second upper metal ring 801 and a second upper metal patch 802 are printed on the upper surface of the upper dielectric substrate 8. The two metal patches have symmetrical structures. The second upper metal patch 802 is located within the second upper metal ring 801 and is isolated from each other, as shown... Figure 3 (d) shows the pink rhomboid ring structure and the pink square frame. The first upper metal ring 611 and the second upper metal ring 801 are both regular quadrilateral closed frames with a width of l2 = 0.2 mm, and are connected by metallized vias 5.

[0041] Reference Figure 3 (c) The structure of the first upper metal patch 612 of the Ka-band dual circularly polarized antenna unit in the embodiment of the present invention will be further described.

[0042] The first upper metal patch 612 consists of a first part 6121, a second part 6122, and a third part 6123, each with a length l6 and l7 of 1.71 mm. The first part 6121 and the second part 6122 are both arrow-shaped, symmetrically arranged with the arrows pointing away from the center of the first dielectric substrate 6, and connected at the tail 6125. The width of the connecting portion 6125 is smaller than the width at the widest point of the arrow, thus forming two symmetrical recesses 6126 at the connection point with a length l8 = 0.45 mm and a width l9 = 0.3 mm. The third part 6123 consists of a length l... 10 =0.87mm, width l 11 The first part 61231 consists of a rectangle 61231 with a radius r2 = 0.8 mm and a semicircular ring 61232 with a radius r2 = 0.25 mm. One side of the rectangle 61231 is connected to the arrow side of the first part 6121, and the semicircular ring 61232 is connected to the opposite side of the rectangle 61231. The metallized blind hole 3 is projected onto the center of the semicircular ring 61232. The fourth part 6124 consists of a rectangle 61241 and a semicircular ring 61242, and has the same structural dimensions as the rectangle 61231 and the semicircular ring 61232 constituting the third part 6123.

[0043] Reference Figure 3 (d) The structure of the second upper metal patch 802 of the Ka-band dual circularly polarized antenna unit in the embodiment of the present invention will be further described.

[0044] The second upper metal patch 802 is a parasitic patch consisting of a first part 8021 and a second part 8022. 8021 is an octagon with a hollowed-out center, with a side length l5 = 2.1 mm and a chamfer length l3 = 0.5 mm. 8022 is the hollowed-out part of 8021, which is a standard square with a side length l4 = 1 mm.

[0045] The Ka-band dual circularly polarized antenna element primarily serves as a radiating structure. The first upper metal patch 612 is coupled and fed through either a metallized blind aperture 3 or a metallized blind aperture 4 to achieve circularly polarized beam radiation. The second upper metal patch 802 is coupled and fed to the first upper metal patch 612 for radiation. Left-hand circular polarization is achieved when fed through the metallized blind aperture 3, and right-hand circular polarization is achieved when fed through the metallized blind aperture 4, thus realizing polarization multiplexing.

[0046] The effects of this invention will be further illustrated below with simulation experiments:

[0047] 1. Simulation experimental conditions.

[0048] The simulation experiment of this invention uses the Ansys Electronics Desktop software platform installed on computer hardware to simulate a Ka-band dual circularly polarized phased array antenna.

[0049] 2. Simulation content and result analysis.

[0050] The simulation experiment of this invention simulates the elements, subarrays, and 8×8 element phased array of the Ka-band dual circularly polarized phased array antenna of this invention in the range of 23GHz to 35GHz. The simulation results are plotted as curves, as shown below. Figure 4 , Figure 5 , Figure 6 As shown. Among them, Figure 4 The image shows the simulation results of the VSWR, axial ratio, and radiation pattern at the center frequency of 29.3 GHz for a Ka-band dual circularly polarized antenna element. Figure 5 The figure shows the simulation results of the axial ratio effect for a Ka-band dual circularly polarized antenna subarray. Figure 6 The radiation scan pattern of gain and axial ratio obtained when simulating an 8×8 Ka-band dual circularly polarized phased array at a center frequency of 29.3 GHz and phi = 0°.

[0051] The effects of the present invention will be further described below with reference to simulation diagrams.

[0052] Figure 4 (a) Figure 4 In (b), the horizontal axis represents the antenna's operating frequency, in GHz. Figure 4 In (a), the vertical axis represents the standing wave ratio. Figure 4 (b) The vertical axis represents the axial ratio, and the unit is GHz. Figure 4 (a) Figure 4 In (b), the curve marked with a black straight line represents the relationship between frequency and standing wave ratio and axial ratio when the simulated antenna element is operating in right-hand circular polarization, and the curve marked with a red dashed line represents the relationship between frequency and standing wave ratio and axial ratio when the simulated antenna element is operating in left-hand circular polarization.

[0053] from Figure 4 (a) and Figure 4 (b) It can be seen that when the Ka-band dual circularly polarized antenna element of this phased array operates in left-hand circular polarization and right-hand circular polarization, the impedance bandwidth with a standing wave ratio of less than 2 is 24.83 to 33.75 GHz, and the axial ratio bandwidth with an axial ratio of less than 3 dB is 29.21 to 33.03 GHz. This proves the consistency of the two circular polarization performances of the dual circularly polarized antenna element of this invention. Polarization multiplexing is achieved through the symmetrical design of the port and patch morphology.

[0054] Figure 4 In (c), the horizontal axis represents the angle of the Theta plane in degrees, and the vertical axis represents the gain in dB. Figure 4In (c), the curve marked with a black straight line represents the curve of gain as a function of the Theta angle in the Phi = 0° plane, and the curve marked with a red dashed line represents the curve of axial ratio as a function of the Theta angle in the Phi = 90° plane.

[0055] from Figure 4 (c) It can be seen that the 3dB beamwidth of the antenna element at 29.3GHz is 109° for both the Phi=0° plane and the Phi=90° plane, indicating that the antenna element is suitable for beam scanning in phased arrays.

[0056] Figure 5 The horizontal axis represents the antenna's operating frequency in GHz, and the vertical axis represents the axial ratio in dB. Figure 5 The curves marked with black straight lines represent the relationship between frequency and axial ratio when the antenna subarray is operating in right-hand circular polarization, while the curves marked with red dashed lines represent the relationship between frequency and axial ratio when the antenna subarray is operating in left-hand circular polarization.

[0057] from Figure 5 It can be seen that when the Ka-band dual circularly polarized antenna subarray of this phased array operates in left-hand circular polarization and right-hand circular polarization, the axial ratio within the operating frequency band is less than 0.2dB. This proves that after the dual circularly polarized antenna elements of this invention are arranged in a 90° sequential rotation, the antenna obtains better main polarization components when operating in left-hand or right-hand circular polarization.

[0058] Figure 6 (a) Figure 6 (b) Figure 6 (c) Figure 6 In (d), the horizontal coordinates all represent the angles of the Theta plane, in degrees (deg). Figure 6 (a) Figure 6 In (c), the vertical axis represents gain. Figure 6 (b) Figure 6 The ordinate of (d) represents the axis ratio, in dB. Figure 6 The curves marked with red straight lines represent the changes in gain or axial ratio as a function of the Theta angle when the beam points to 0°, while the curves marked with blue dashed lines represent the changes in gain or axial ratio as a function of the Theta angle when the beam points to 60°.

[0059] from Figure 6 It can be seen that: when the phased array of the present invention points to 0° at 29.3 GHz, the Ka-band dual circularly polarized phased array antenna has a beamwidth of 13°, a sidelobe level of 9.3 dB, and an axial ratio of less than 3 dB. When the phased array of the present invention scans 60° at 29.3 GHz, the Ka-band circularly polarized phased array antenna has a beamwidth of 24° and an axial ratio of less than 3 dB when the beampoint is 60°.

[0060] The simulation experiments above show that this invention solves the problem of high profile and complex structure that prevents polarization reuse in current circularly polarized phased array antennas by using a double-layer dielectric substrate and a symmetrical design. Because the feed network design is eliminated, and the left-hand and right-hand circular polarization are directly excited by connecting the radiating patches through the left and right-hand circular ports, the overall antenna profile is low. Due to the antenna shape design and the introduction of parasitic patches other than the main radiating patch, circular polarization is formed through the combined action of the two patches. The Ka-band dual-circularly polarized antenna element has consistent left-hand and right-hand circular polarization performance and a wide beamwidth, making it suitable for beam scanning in Ka-band dual-circularly polarized phased arrays.

[0061] The specific embodiments of the present invention do not constitute any limitation on the present invention. Obviously, those skilled in the art, after understanding the content and principles of the present invention, may make various modifications and changes in form and details without departing from the principles and structure of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the protection scope of the claims of the present invention.

Claims

1. A low-profile, dual-circularly polarized Ka-band phased array antenna, comprising N×N antenna arrays arranged in a rectangular, closely spaced configuration, each antenna array consisting of 4×4 Ka-band dual-circularly polarized antenna subarrays, wherein... N is an integer greater than or equal to 2; characterized in that each antenna element in each antenna subarray is composed of two layers of dielectric substrate, the feeding structure and the metal patch structure are symmetrical, and the left and right circularly polarized feeding structure is directly connected to the metal patch structure; each antenna subarray is composed of 4 Ka-band dual circularly polarized antenna elements (11), (12), (13) and (14), arranged in a 90° sequential rotation array with antenna element (11) as the reference point; a feeding transmission structure (2) is provided below each antenna subarray; the antenna elements in each antenna subarray The term "consisting of two dielectric substrates" refers to the following layers arranged sequentially from bottom to top: a lower dielectric substrate (6), a middle prepreg layer (7), and an upper dielectric substrate (8). The lower dielectric substrate (6) has left-hand circular polarization feeding structures mirror-symmetrically arranged at the port positions, with metallized blind vias (3) and (4) penetrating the lower dielectric substrate (6). When fed through the metallized blind via (3), left-hand circular polarization is achieved, and when fed through the metallized blind via (4), right-hand circular polarization is achieved. Multiple equally spaced metallized vias (5) penetrate the lower dielectric substrate. (6) Intermediate semi-cured layer (7) and upper dielectric substrate (8); the upper surface of the lower dielectric substrate (6) is printed with a first upper metal ring (611) and a first upper metal patch (612), the two metal patches having symmetrical structures; the metal patch (612) is located inside the first upper metal ring (611) and is isolated from each other; the upper surface of the upper dielectric substrate (8) is printed with a second upper metal ring (801) and a second upper metal patch (802), the two metal patches having symmetrical structures; the second upper metal patch (802) The first upper metal ring (611) and the second upper metal ring (801) are located inside the second upper metal ring (801) and are isolated from each other; both the first upper metal ring (611) and the second upper metal ring (801) are closed frames of regular quadrilaterals and are connected through the metallized via (5); the second upper metal patch (802) is composed of a first part (8021) and a second part (8022); the first part (8021) is an octagon with a hollowed-out center, and the second part (8022) is the hollowed-out center part of the first part (8022), which is a standard regular quadrilateral.

2. The low-profile dual-circularly polarized Ka-band phased array antenna according to claim 1, characterized in that, The power supply transmission structure (2) includes four left-hand circular polarization ports and four right-hand circular polarization ports. The left-hand and right-hand circular polarization ports are arranged in a cross pattern, and each port is connected to a phase shifter.

3. The low-profile dual-circularly polarized Ka-band phased array antenna according to claim 2, characterized in that, The rotation angle of the Ka-band dual circularly polarized antenna element is equal to the phase of the phase shifter connected to its corresponding port; when working at the left-hand circularly polarized port, the rotation angle and phase of antenna elements (11), (12), (13) and (14) are 0°, 90°, 180° and 270° respectively; when working at the right-hand circularly polarized port, the rotation angle and phase of antenna elements (11), (12), (13) and (14) are 0°, 270°, 180° and 90° respectively.

4. A low-profile, dual-circularly polarized Ka-band phased array antenna according to claim 3, characterized in that, The horizontal cross-sections of the lower dielectric substrate (6), the intermediate semi-cured layer (7), and the upper dielectric substrate (8) are regular quadrilaterals and have equal areas.

5. A low-profile, dual-circularly polarized Ka-band phased array antenna according to claim 4, characterized in that, The sum of the height of the lower dielectric substrate (6), the height of the intermediate semi-cured layer (7), and the height of the upper dielectric substrate (8) is less than 2 mm.

6. A low-profile, dual-circularly polarized Ka-band phased array antenna according to claim 5, characterized in that, The first upper metal patch (612) is composed of a first part (6121), a second part (6122), a third part (6123), and a fourth part (6124). The first part (6121) and the second part (6122) are both arrow-shaped, with the arrows pointing symmetrically away from the center of the first dielectric substrate (6) and connected at the tail. The width of the connection part is less than the width of the widest part of the arrow. The third part (6123) and the fourth part (6124) are both composed of a rectangle and a semicircular ring. One side of the rectangle is connected to the arrow side of the first part, and the other side is connected to the semicircular ring. The fourth part (6124) is symmetrically arranged with the third part (6123).

7. A low-profile, dual-circularly polarized Ka-band phased array antenna according to claim 6, characterized in that, The first upper metal patch (612) is fed through the metallized blind hole (3) or (4) of the feeding structure. The second upper metal patch (802) is coupled to the first upper metal patch (612) for radiation. When fed through the metallized blind hole (3), left-hand circular polarization is achieved. When fed through the metallized blind hole (4), right-hand circular polarization is achieved, thus realizing polarization multiplexing.

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