A logarithmic-periodic antenna and an ultra-wideband dual-polarized low-profile conformal array antenna

Abstract

The application discloses a logarithmic-periodic antenna and an ultra-wideband dual-polarized low-profile conformal array antenna, and belongs to the technical field of design and manufacture of ultra-wideband antennas. An array element is composed of two types of antennas, i.e. a miniaturized logarithmic-periodic antenna and a Vivaldi antenna, which are complexly nested and structurally multiplexed. The proposed miniaturized logarithmic-periodic antenna is designed to be broadband, small and conformal through composite loading methods such as loading on the top of the array element, bending part of the array element and loading a dielectric block on part of the array element. On this basis, a design method for forming a dual-polarized antenna by nesting a Vivaldi antenna and a logarithmic-periodic antenna is proposed. The Vivaldi antenna is designed in a left-right block manner, and is spliced to form a radiation slot and an excitation slot. The collection line of the logarithmic-periodic antenna is arranged on the left and right fan plates of the Vivaldi antenna. This dual-polarized array forming mode takes into account the large-curvature conformality in the elevation plane, and can realize wide-beam coverage in the elevation plane and wide-angle scanning in the azimuth plane.

Description

Technical Field

[0001] This invention relates to the field of ultra-wideband antenna design and manufacturing technology, and specifically to an ultra-wideband dual-polarized low-profile conformal array antenna. Background Technology

[0002] On airborne conformal platforms, antenna installation dimensions are limited, and installation locations are often irregular structures. Antenna integration also involves considerations of radar cross section (RCS) and aerodynamics, thus requiring the number of antennas to be as small as possible and the antenna profile to be as low as possible. Therefore, there is a strong demand for broadband low-profile conformal array antennas.

[0003] According to literature review, current ultra-wideband conformal phased array antennas mainly take the form of tightly coupled dipole antennas (TCDA / PUMA) or ultra-wideband end-fire arrays, and the mounting platform is planar or a relatively regular curved surface. Furthermore, the dual-polarization design of low-profile end-fire arrays still needs breakthroughs. Communication capacity can be significantly improved through polarization diversity, frequency diversity, and other methods. Zhang Shaolin et al. proposed a dual-polarization log-periodic antenna in their invention patent "Dual-Polarized Log-Periodic Antenna, Dual-Element Structure Antenna, and Antenna Array" (application number: 201911119825.4). The antenna body consists of four connecting lines and multiple antenna elements arranged alternately and equally spaced parallel on them. This composite structure achieves vertical / horizontal dual polarization of the antenna, reducing signal polarization loss and obtaining good dual-polarization gain and radiation symmetry. However, its additional feeding structure occupies considerable space, and the antenna profile is relatively high. Miao Jungang et al. proposed a dual-polarized Vivaldi array antenna in their invention patent application (application number: 202410454347.7), where the horizontal and vertical sub-arrays are integrally formed, resulting in a relatively simple structure and stable and reliable performance. However, the bandwidth of the Vivaldi antenna is proportional to its vertical profile height, so the profile height becomes excessive when meeting broadband requirements. Furthermore, the consistent width at the front and rear ends of the Vivaldi antenna cannot meet the requirements for large curvature conformal antennas.

[0004] In the miniaturization of log-periodic antennas, researchers have explored various methods to reduce antenna size. For example, loading different shapes onto the dipole element can effectively reduce its length. Wang Zhijuan et al., in their invention patent "A Novel Ultra-Wideband High-Gain Miniaturized Log-Periodic Antenna" (application number: 202010751679.3), proposed that loading a top-hat structure onto the dipole element and adding inductive loads to part of the element can effectively reduce the element length, shortening the lateral dimension of the log-periodic antenna to 0.25. It also takes into account ultra-wideband and high-gain characteristics. However, there is still room for improvement in reducing the lateral size of the antenna in this miniaturization method, because when the number of elements on a log-periodic antenna increases, the radiating arm of the second half of the element is still too long. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings and deficiencies of existing technologies by providing a miniaturized log-periodic antenna design scheme, and to combine this miniaturized log-periodic antenna with a Vivaldi antenna in a composite nested design to form a novel broadband dual-polarized array antenna that can accommodate both wide beam coverage in the elevation plane and wide-angle scanning in the azimuth plane.

[0006] This invention is achieved through the following technical solution: A miniaturized log-periodic antenna includes a dipole element, a duct line, and a dielectric matching block; There are two convergence lines, which are arranged in parallel; there are N pairs of dipole oscillators, where N≥1; the N pairs of dipole oscillators are divided into two groups and connected to the two convergence lines respectively; the dipole oscillators on the same convergence line are staggered from top to bottom; the dipole oscillators at the same height are connected to the two convergence lines respectively. Furthermore, there is a medium strip between the two junction lines.

[0007] Furthermore, each dipole oscillator is loaded with a top-hat structure.

[0008] Furthermore, the top-hat structure is a U-shaped stub, the opening of which is directly opposite the radiating arm of the dipole oscillator it corresponds to; the radiating arm is connected inside the U-shaped stub to form an E-shape.

[0009] Furthermore, the radiating arm of the low-frequency dipole oscillator is in the form of a meandering curve.

[0010] Furthermore, the top-hat structure of the low-frequency dipole oscillator has a bent structure at its end; a dielectric matching block is loaded in the area enclosed by the radiating arm, the top-hat structure, and the bent structure of the low-frequency dipole oscillator.

[0011] An ultrawideband dual-polarized low-profile conformal array antenna includes a Vivaldi antenna and at least two miniaturized log-periodic antennas; the log-periodic antennas are parallel to each other and arrayed along a straight line; The Vivaldi antenna includes a left sector plate and a right sector plate located in the same vertical plane; a radiation slot is formed between the left sector plate and the right sector plate, and the width of the radiation slot gradually decreases from top to bottom; The bottom of the left sector plate is provided with a matching groove, which is rectangular; the radiation groove is connected to the matching groove through the excitation groove. The Vivaldi antenna is located between two adjacent log-periodic antennas, with the left and right sectors connected to the corresponding crossbars.

[0012] Furthermore, it also includes a base plate and a feeding structure; the Vivaldi antenna and the log-periodic antenna are both mounted on the upper surface of the base plate; the vertical plane where the Vivaldi antenna is located and the vertical plane where the log-periodic antenna is located are perpendicular to each other, and both the Vivaldi antenna and the log-periodic antenna are perpendicular to the base plate; The feeding structure includes a feeding coaxial cable and a feeding coaxial probe; the feeding coaxial cable passes through the interior of one of the bundles, with the inner conductor connected to the other bundle; the feeding coaxial probe is connected to the bottom of the Vivaldi antenna.

[0013] Furthermore, the excitation slot is divided into two sections: a first excitation slot and a second excitation slot. One end of the first excitation slot is connected to the radiation slot and extends vertically. The second excitation slot is a horizontal section, with one end connected to the bottom of the matching slot and the other end connected to the first excitation slot.

[0014] Furthermore, right and left sector plates are respectively provided on the log-periodic antenna at the front and rear ends of the linear array. The right sector is connected to the outer convergence line of the front log-periodic antenna; the left sector is connected to the rear log-periodic antenna.

[0015] Compared with the prior art, the beneficial effects of the present invention are: First, a miniaturized log-periodic antenna is proposed, achieving a broadband, miniaturized, conformal design through a combination of three methods: top-hat loading, partial element bending, and partial element loading with dielectric blocks. Second, a design method is proposed to nest a Vivaldi antenna and a log-periodic antenna to form a dual-polarized antenna. The Vivaldi antenna is designed with left and right blocks, which are spliced ​​together to form radiating and excitation slots. The convergence lines of the log-periodic antenna are then deployed on the left and right sectors of the Vivaldi antenna. This dual-polarized array method accommodates the large curvature conformality of the elevation plane, enabling wide beam coverage in the elevation plane and wide-angle scanning applications in the azimuth plane. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural schematic diagram of an ultra-wideband dual-polarized low-profile conformal array antenna according to the present invention; Figure 2 This is a three-dimensional structural schematic diagram of an ultra-wideband dual-polarized low-profile conformal antenna element according to the present invention; Figure 3 This is a three-dimensional structural schematic diagram of a miniaturized log-periodic antenna according to the present invention; Figure 4This is a schematic diagram of the dipole oscillator distribution on a miniaturized log-periodic antenna according to the present invention; Figure 5 This is a schematic diagram of the ductwork section structure of a miniaturized log-periodic antenna according to the present invention; Figure 6 This is a schematic diagram of the structure and feed interface of a Vivaldi antenna according to the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] An ultra-wideband dual-polarized low-profile conformal array antenna includes a high-curvature radome 1, an ultra-wideband dual-polarized low-profile conformal antenna 2, a feeding structure 3, and a base plate 4. The surface of the high-curvature radome 1 is a high-curvature irregular surface adapted to the contour of the conformal platform. The ultra-wideband dual-polarized low-profile conformal antenna 2 consists of multiple miniaturized log-periodic antennas 21 and multiple Vivaldi antennas 22. The feeding structure 3 consists of a feeding coaxial cable and a feeding coaxial probe 32.

[0019] The miniaturized log-periodic antenna 21 includes a top-hat-loaded dipole element 211, a connecting line 212, and a dielectric matching block 213. Dielectric strips 2121 are filled between the connecting lines 212 to prevent short circuits caused by structural deformation.

[0020] The miniaturized log-periodic antenna 21 has a total of N pairs of top-hat loaded dipole elements 211, which are distributed symmetrically in opposite directions on both sides of the convergence line 212. In order to further reduce the antenna profile width, we adopted a meandering design for the radiating arms of some low-frequency dipole elements 211, and adopted a folded and extended design for the top-hat loading.

[0021] The end of the radiating arm of the dipole oscillator 211 is connected to the junction line 212. The dielectric matching block 213 is located inside the region enclosed by part of the low-frequency dipole oscillator 211, and plays a further matching role for the folded oscillator.

[0022] The Vivaldi antenna 22 consists of a left sector plate 221, a right sector plate 222, a radiation slot 223, a first excitation slot 224, a second excitation slot 225, and a matching slot 226. The excitation slot 225 and the matching slot 226 are etched on the left sector plate 221. When the left sector plate 221 and the right sector plate 222 are spliced ​​together, the structural design ensures that the first excitation slot 224 and the radiation slot 223 are formed.

[0023] One end of the radiation slot 223 is connected to the first excitation slot 224, and the other end opens into free space. The radiation slot 223, the first excitation slot 224, the second excitation slot 225, and the matching slot 226 are connected.

[0024] The Vivaldi antenna 22 and the miniaturized log-periodic antenna 21 are both flat antenna elements that are electrically ground planes for each other.

[0025] The Vivaldi antenna 22 and the miniaturized log-periodic antenna 21 are arranged vertically. The miniaturized log-periodic antenna 21 is deployed on the left side of the left sector 221 and the right side of the right sector 222. A pair of convergent lines 212 of the miniaturized log-periodic antenna are distributed on the left sector 221 and the right sector 222 of the Vivaldi antenna.

[0026] When the ultra-wideband dual-polarized low-profile conformal antenna 2 is arrayed with multiple elements, a one-dimensional array is formed by sequentially splicing the left sector plate 221 and the right sector plate 222. Another-dimensional array can be formed along the direction of extension of the logarithmic periodic elements.

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments: The ultra-wideband dual-polarized low-profile conformal array antenna provided in this embodiment contains 16 array elements, and its structure is as follows: Figures 1 to 6 As shown, from top to bottom, it includes a large curvature radome 1, an ultra-wideband dual-polarized low-profile conformal antenna 2, a feeding structure 3, and a base plate 4.

[0028] like Figure 1 As shown, the surface of the large-curvature radome 1 is a large-curvature irregular surface adapted to the contour of the conformal platform. The ultra-wideband dual-polarization low-profile conformal array antenna is an end-fire antenna array, containing 16 vertically polarized elements and 16 horizontally polarized elements. The array antenna structure is based on a base plate, and the 16 antenna elements are fixed to the base plate 4 by screws to the large-curvature radome 1.

[0029] like Figure 2 As shown, the ultra-wideband dual-polarized low-profile conformal antenna 2 consists of a miniaturized log-periodic antenna 21 and a Vivaldi antenna 22. The miniaturized log-periodic antenna 21 is fixed to the Vivaldi antenna 22 by screw connections. Angular domain coverage is achieved through beam coverage in the elevation direction. To achieve a ±60° scanning range in the azimuth plane, the element spacing in the azimuth plane is chosen to be 0.53λ. H .

[0030] like Figure 3 As shown, the miniaturized log-periodic antenna 21 includes a top-hat-loaded dipole element 211, a culminating line 212, and a dielectric matching block 213. The dielectric matching block 213 is partially wrapped by the low-frequency dipole element, providing further matching for the folded dipole element.

[0031] like Figure 4 As shown, the miniaturized log-periodic antenna 21 has a total of N pairs of dipole elements 211 loaded with a top-hat, which are symmetrically distributed on both sides of the assembly line 212. Taking a design with 15 pairs of elements as an example, starting from the top, the elements are numbered in order of length from shortest to longest as follows: 1: 2111, 2: 2112, 3: 2113, 4: 2114, 5: 2115, 6: 2116, 7: 2117, 8: 2118, 9: 2119, 10: 21110, 11: 21111, 12: 21112, 13: 21113, 14: 21114 and 15: 21115. The height of the oscillator from the plane containing the connecting line is 11.02mm, 12.73mm, 14.67mm, 16.88mm, 19.38mm, 22.24mm, 25.47mm, 29.15mm, 33.33mm, 38.08mm, 43.48mm, 49.61mm, 56.85mm, 64.5mm, and 73.5mm, respectively, from number 1 to 15.

[0032] like Figure 4 As shown, to further reduce the antenna profile width, we adopted a meandering design for the radiating arms of dipole elements 13-15, and a folded extension design for the top-hat loading. The lateral dimension of the miniaturized log-periodic antenna 21 can be shortened to 103 mm, approximately 0.12 mm. (The lowest frequency corresponds to the wavelength.)

[0033] like Figure 5 As shown, dielectric strips 2121 are filled between the connecting lines 212 to prevent short circuits caused by structural deformation. The radiating arms of all dipole elements 211 are cuboid in shape, with one end connected to the connecting line 212. The connecting lines are a pair, both cuboids, with an internal perforation on one side through which the feed coaxial cable 31 passes, and the inner conductor connected to the other side. The maximum radiation direction of the miniaturized log-periodic antenna 21 is from the longest element towards the shortest element.

[0034] like Figure 6 As shown, the Vivaldi antenna 22 consists of a left sector plate 221, a right sector plate 222, a radiating slot 223, a first excitation slot 224, a second excitation slot 225, and a matching slot 226. The second excitation slot 225 and the matching slot 226 are etched onto the left sector plate. When the left sector plate 221 and the right sector plate 222 are joined, the structural design ensures the formation of the first excitation slot 224 and the radiating slot 223. One end of the radiating slot 223 is connected to the first excitation slot 224, and the other end opens into free space. The radiating slot 223, the first excitation slot 224, the second excitation slot 225, and the matching slot 226 are interconnected.

[0035] like Figure 6 As shown, the feed coaxial probe 32 is connected to the tail end of the Vivaldi antenna 22 to feed the antenna. The signal starts to propagate forward from the tail end, gradually expanding and radiating out along the exponential feed slot.

[0036] like Figure 6 and Figure 1 As shown, when assembling a multi-element array of the ultra-wideband dual-polarized low-profile conformal antenna 2, a one-dimensional array is formed by sequentially splicing the left sector plate 221 and the right sector plate 222. Alternatively, a other-dimensional array can be formed along the direction of extension of the logarithmic periodic elements.

[0037] The characteristics of the ultra-wideband dual-polarized low-profile conformal array antenna described in this invention were simulated using the electromagnetic simulation software Ansys Electronics Desktop. When the antenna operates at a frequency of 0.35 GHz to 0.5 GHz, the VSWR is ≤6; when it operates at a frequency of 0.5 GHz to 2 GHz, the VSWR is ≤2.5. The scan level drop of the conformal array antenna is less than 6 dB within a range of ±60°.

[0038] It should be noted that the above description is merely a preferred application example of the present invention and is not intended to limit the scope of protection of the present invention. All technical solutions employing equivalent substitutions or equivalent transformations are within the scope of protection of the present invention.

Claims

1. A miniaturized log-periodic antenna, characterized in that, It includes a dipole oscillator (211), a connecting line (212), and a dielectric matching block (213); There are two convergence lines (212), which are arranged in parallel; there are N pairs of dipole oscillators (211), where N≥1; the N pairs of dipole oscillators (211) are divided into two groups and connected to the two convergence lines respectively; the dipole oscillators (211) on the same convergence line are staggered from top to bottom; the dipole oscillators (211) at the same height are connected to the two convergence lines respectively; There is a medium strip (2121) between the two junction lines (212); Each dipole oscillator (211) is loaded with a top-hat structure; The top-hat structure is a U-shaped branch, the opening of which is directly opposite the radial arm of the dipole oscillator (211) it faces; the radial arm is connected inside the U-shaped branch to form an E-shape; The radiating arms of the low-frequency dipole oscillator (211) are in the form of a meandering curve; The top-hat structure of the low-frequency dipole oscillator (211) has a bent structure at its end; a dielectric matching block (213) is loaded in the area enclosed by the radiating arm, the top-hat structure and the bent structure of the low-frequency dipole oscillator (211).

2. An ultra-wideband dual-polarized low-profile conformal array antenna, characterized in that, It includes a Vivaldi antenna (22) and at least two miniaturized log-periodic antennas (21) as described in claim 1; the log-periodic antennas (21) are parallel to each other and arranged in a straight line array; The Vivaldi antenna (22) includes a left sector plate (221) and a right sector plate (222) located in the same vertical plane; a radiation slot (223) is provided between the left sector plate (221) and the right sector plate (222), and the width of the radiation slot (223) gradually decreases from top to bottom; The bottom of the left sector plate (221) is provided with a matching groove (226), which is rectangular; the radiation groove (223) is connected to the matching groove (226) through the excitation groove; The Vivaldi antenna (22) is located between two adjacent log-periodic antennas (21), wherein the left sector (221) and the right sector (222) are respectively connected to the cross line (212) on the corresponding side.

3. The ultra-wideband dual-polarized low-profile conformal array antenna according to claim 2, characterized in that, It also includes a base plate (4) and a feeding structure (3); the Vivaldi antenna (22) and the log-periodic antenna (21) are both mounted on the upper surface of the base plate (4); The vertical plane where the Vivaldi antenna (22) is located is perpendicular to the vertical plane where the log-periodic antenna (21) is located, and both the Vivaldi antenna (22) and the log-periodic antenna (21) are perpendicular to the base plate (4). The feeding structure (3) includes a feeding coaxial cable (31) and a feeding coaxial probe (32); the feeding coaxial cable (31) passes through the interior of one of the bundles (212), and the inner conductor is connected to the other bundle (212); the feeding coaxial probe (32) is connected to the bottom of the Vivaldi antenna (22).

4. The ultra-wideband dual-polarized low-profile conformal array antenna according to claim 2, characterized in that, The excitation slot is divided into two sections: a first excitation slot (224) and a second excitation slot (225). One end of the first excitation slot (224) is connected to the radiation slot (223) and extends vertically. The second excitation slot (225) is a horizontal section, with one end connected to the bottom of the matching slot (226) and the other end connected to the first excitation slot (224). The bottom of the left sector plate (221) and the right sector plate (222) are connected; the second excitation slot (225) and the matching slot (226) are located above the connection part.

5. The ultra-wideband dual-polarized low-profile conformal array antenna according to claim 2, characterized in that, The log-periodic antenna (21) at the head end and the log-periodic antenna (21) at the tail end of the linear array are respectively provided with a right sector plate (222) and a left sector plate (221). The right sector (222) is connected to the outer convergence line (212) of the front log-periodic antenna (21); the left sector (221) is connected to the rear log-periodic antenna (21).

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