Miniaturized multi-band polarization diversity array antenna device

Abstract

The application relates to the technical field of passive antenna design and manufacturing, in particular to a miniaturized multi-frequency polarized diversity array antenna device suitable for engineering application, characterized in that different-thickness microwave broadband wave-absorbing materials are arranged on the inner and outer sides of a cylindrical carrier platform, a printed monopole antenna array is arranged on the cylindrical carrier and closely arranged along the circumference of the cylindrical carrier, monopole antenna units are arranged in the printed monopole antenna array, and the radiators of the printed monopole antenna array are located in the internal area of the cylindrical metal carrier; a monopole mirror Vivaldi antenna array is arranged along the circumference and arranged in a shape-following mode and located in the outer area of the cylindrical carrier platform, monopole mirror Vivaldi antenna units are arranged in the monopole mirror Vivaldi antenna array, the number of the monopole mirror Vivaldi antenna units is the same as that of the printed monopole antenna units, the antenna units are one-to-one corresponding between the two, and respectively form polarized diversity antenna pairs with approximately orthogonal polarization.

Description

Technical Field

[0001] This invention relates to the field of passive antenna design and manufacturing technology, specifically a miniaturized multi-band polarization diversity array antenna device that achieves miniaturization by compressing the size of antenna elements; while ensuring the polarization isolation and radiation pattern coverage of the polarization diversity antenna, the designed antenna system is relatively stable in electrical performance, easy to install mechanically, and has a reliable structure, making it suitable for engineering applications. Background Technology

[0002] In electronic reconnaissance, passive radar guidance, and electronic jamming systems, broadband passive antenna systems are crucial components. To measure the direction of arrival (DOA) of signals from multiple radiation sources, passive radar systems typically employ antenna arrays to receive the incident signals. On aircraft platforms, due to limited antenna installation space, miniaturization is a critical task to accommodate more antenna elements within a confined space. Currently, there are many common types of passive radar receiving antennas, such as: ultra-wideband log-periodic antennas, ultra-wideband Archimedean spiral antennas, ultra-wideband equiangular spiral antennas, ultra-wideband butterfly antennas, ultra-wideband sinusoidal antennas, ultra-wideband Vivaldi antennas, and ultra-wideband horn antennas. Passive radar antennas receive signals from radiation sources within an ultra-wideband or multi-band environment. Passive radar performs signal detection, information measurement, and target tracking. Typical passive radars employ ultra-wideband antennas with single polarization, such as ultra-wideband log-periodic antennas, ultra-wideband butterfly antennas, ultra-wideband sinusoidal antennas, ultra-wideband Vivaldi antennas, and ultra-wideband horn antennas (linear polarization), and ultra-wideband Archimedean spiral antennas and ultra-wideband equiangular spiral antennas (circular polarization). With the development of electronic information technology, the polarization information of electromagnetic waves has received increasing attention and is being widely applied. In passive radar systems, using polarization-sensitive arrays can obtain the polarization information of radiation source signals, significantly increasing the amount of information the radar system can acquire. This provides valuable resources for radar target detection and identification. Therefore, ultra-wideband or multi-band polarization-sensitive array antennas have been extensively researched and applied. In polarization-sensitive arrays, polarization diversity is an effective method for sensing polarization information. Using polarization diversity antenna arrays, on the one hand, interferometers or spatial spectrum techniques can be used to detect and measure the angle of radiation source signals; on the other hand, radar systems can obtain the polarization parameters of the radiation source signals, thus enabling polarization signal processing algorithms. There are many types of polarization diversity antennas. Currently, common dual-polarization antennas include dual-polarization orthogonal symmetrical dipole antennas, orthogonal dual-polarization magnetoelectric dipole antennas, dual-polarization horn antennas, dual-polarization log-periodic antennas, dual-polarization Vivaldi antennas, and dual-polarization sinusoidal antennas. For limited aircraft platforms, researching miniaturized polarization diversity multi-band antenna array systems has practical application value. Summary of the Invention

[0003] This invention addresses the shortcomings and deficiencies of existing technologies by proposing a miniaturized multi-band polarization diversity array antenna device that compresses the size of antenna elements. While ensuring the polarization isolation and radiation pattern coverage of the polarization diversity antenna, the designed antenna system exhibits stable electrical performance, convenient mechanical installation, and reliable structure, making it suitable for engineering applications.

[0004] This invention achieves its purpose through the following measures: A miniaturized multi-band polarization-diversified cylindrical carrier platform made of metal is characterized by having microwave broadband absorbing materials of different thicknesses disposed on the inner and outer sides of the cylindrical carrier platform. A printed monopole antenna array is arranged closely along the circumference of the cylindrical carrier, with monopole antenna elements within the array. The radiators of the printed monopole antenna array are located in the inner region of the cylindrical metal carrier. A monopole mirror Vivaldi antenna array is arranged in a conformal layout along the circumference and located in the outer region of the cylindrical carrier platform. The monopole mirror Vivaldi antenna array contains monopole mirror Vivaldi antenna elements, the number of which is the same as the number of printed monopole antenna elements. The antenna elements of the two arrays correspond one-to-one, forming polarization diversity antenna pairs with approximately orthogonal polarization. The monopole antenna radiator arm in the printed monopole antenna unit includes a fan-shaped annular portion at the front and a chamfered rectangular portion at the rear. The monopole antenna radiator arm is excited by a coplanar waveguide (CPW). The CPW structure that excites the metal arm of the antenna radiator includes a region connected to the monopole radiator arm, a uniform CPW region connected to the coaxial cable for feeding, and a continuous impedance transformation section between the two. The copper foil ground plane where the CPW feeding structure is located is trapezoidal to facilitate impedance matching with the monopole radiator arm. Multiple monopole radiator units form a circumferentially closely arranged multi-band antenna array, forming a passive radar signal receiving antenna array with polarization. Gaps are left between the monopole radiator arm units. A rectangular coupling plate is set on the other side of the printed dielectric substrate to increase the electromagnetic coupling between the monopole radiator arms and improve the impedance and radiation pattern performance in the low-frequency band. A circular metal reflector structure is placed below the printed dielectric substrate where the monopole radiator array is located to control the radiation pattern of the monopole radiator array.

[0005] In this invention, the characteristic impedance of the uniform CPW connected to the coaxial cable of the monopole antenna element radiator is 50 ohms. The characteristic impedance of the coplanar waveguide can be calculated by the following formula, defining variables. and Their values ​​are respectively (1), (2), In the formula: The thickness of the dielectric substrate; The width of the dielectric substrate; The width of the coplanar waveguide feed line; The gap width between the coplanar waveguide feed and the ground plane; the effective relative permittivity of the dielectric substrate is: (3), In the formula: , , , These are the first-order complete elliptic integral function and its complement, respectively, and their specific expressions are as follows: (4), The characteristic impedance of a coplanar waveguide can be expressed as: (5).

[0006] This invention employs a metal-structured monopole mirror Vivaldi antenna array to achieve a receiving channel that is approximately orthogonal to the monopole radiator, thus creating a polarization diversity effect. A metal ground plane is placed in the center region of the radiating slot of a traditional Vivaldi antenna. This metal ground plane is perpendicular to the metal sheet containing the Vivaldi antenna radiator, eliminating half of the radiator structure while approximately preserving the original radiation effect, achieving excellent miniaturization. Rectangular metal sheet structures, forming an approximate electromagnetic boundary mirror ground plane, are set on the upper and lower sides of the monopole Vivaldi radiator vibrator. These metal sheet structures are perpendicular to the metal sheet region of the Vivaldi antenna radiator, and their heights differ on the upper and lower sides. Dielectric blocks with a dielectric constant are placed on both sides of the metal arm of the radiator to improve the radiation efficiency of the monopole mirror Vivaldi radiator, improve the impedance characteristics at low frequencies, and reduce the return loss at low frequencies. The dielectric blocks on the front and rear sides have different shapes and thicknesses to increase the degree of freedom in impedance tuning. Multiple monopole mirror Vivaldi antenna elements are installed in a circumferential arrangement to form a cylindrical conformal layout of an ultra-wideband miniaturized antenna array, which is used to achieve beam coverage in a certain area in front of the aircraft structure. Microwave absorbing materials are placed on the inner and outer surfaces of the cylindrical metal carrier to reduce the installation height of the monopole mirror Vivaldi antenna, improve the impedance and radiation performance of the antenna array, and improve the electromagnetic isolation performance between polarization diversity antenna composite antenna arrays.

[0007] The exponential curve equation used for the metal radiating arm of the monopole mirror Vivaldi antenna element in this invention is: (6) In the formula, and According to respectively , , , and Confirmed, here. This represents the length of the straight-line slot from the origin, corresponding to the length of a conventional Vivaldi antenna compared to a monopole mirrored Vivaldi antenna. For a straight gap, the width is [value]; for an exponentially gradient gap, the width is [value]. The length of the exponentially gradient gap. The constant of the exponential curve, This refers to the width of a conventional Vivaldi antenna corresponding to a monopole mirrored Vivaldi antenna; here, we use... .

[0008] In this invention, the shape of the dielectric block loaded inside the monopole mirror Vivaldi antenna element is determined by parameters. , , and the thickness of the dielectric block Confirmed; the thickness of the dielectric block loaded on the outside of the monopole mirror Vivaldi antenna is... It is rectangular in shape and fills the entire surface of the metal vibrator arm of the monopole mirror Vivaldi antenna radiator.

[0009] In summary, this invention presents a multi-band polarization diversity passive detection radar antenna system. This antenna design is characterized by ease of design, simple structure, low cost, and miniaturization. While ensuring polarization isolation and radiation pattern coverage of the polarization diversity antenna, the designed antenna system exhibits stable electrical performance, convenient mechanical installation, and reliable structure, making it suitable for engineering applications. The multi-band polarization diversity passive detection radar antenna device of this invention is suitable for use in passive guidance radar, electronic reconnaissance systems, electronic jamming systems, and electronic countermeasures systems, demonstrating significant practical application value. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of the present invention. Figure 1 (a) is a three-dimensional structural model of the polarization diversity multi-band antenna array, 1(b) is a front view of the polarization diversity multi-band antenna array, 1(c) is a rear view of the polarization diversity multi-band antenna array, 1(d) is a left view of the polarization diversity multi-band antenna array, and 1(e) is a right view of the polarization diversity multi-band antenna array.

[0011] Figure 2 This is a schematic diagram of the structure of the CPW-fed monopole antenna elements arranged circumferentially in this invention. In this diagram, 2(a) is a three-dimensional structural model of the CPW-fed monopole antenna array, 2(b) is a front view of the CPW-fed monopole antenna array, 2(c) is a rear view of the CPW-fed monopole antenna array, 2(d) is a top view of the CPW-fed monopole antenna array, 2(e) is a rear view of the CPW-fed monopole antenna array after hiding the annular reflector, and 2(f) is a front view of the CPW-fed monopole antenna element.

[0012] Figure 3 This is a schematic diagram of a circumferentially arranged monopole mirror Vivaldi antenna system. Figure 3 (a) is a three-dimensional structural model of a monopole-mirrored Vivaldi antenna array; 3(b) is a front view of the monopole-mirrored Vivaldi antenna array; 3(c) is a rear view of the monopole-mirrored Vivaldi antenna array; 3(d) is a top view of the monopole-mirrored Vivaldi antenna array; 3(e) is a left view of the monopole-mirrored Vivaldi antenna array; 3(f) is a three-dimensional structural model of a monopole-mirrored Vivaldi antenna element; 3(g) is a front view of a monopole-mirrored Vivaldi antenna element; 3(h) is a rear view of a monopole-mirrored Vivaldi antenna element; 3(i) is a left view of a monopole-mirrored Vivaldi antenna element; 3(j) is a right view of a monopole-mirrored Vivaldi antenna element; 3(k) is a three-dimensional structural model of a monopole-mirrored Vivaldi antenna element with the loaded dielectric structure hidden; 3(l) is a left view of a monopole-mirrored Vivaldi antenna element with the loaded dielectric structure hidden; 3(m) is a right view of a monopole-mirrored Vivaldi antenna element with the loaded dielectric structure hidden.

[0013] Figure 4 These are simulation results of the return loss and port isolation of the antenna port in this embodiment of the invention. Figure 4 (a) is the return loss of port 1, 4(b) is the isolation between antenna port 1 and port 2, 4(c) is the isolation between antenna port 1 and port 3, 4(d) is the isolation between antenna port 3 and port 4, 4(e) is the isolation between antenna port 4 and port 5, 4(f) is the isolation between antenna port 1 and port 10, 4(g) is the return loss of port 10, 4(h) is the isolation between antenna port 10 and port 11, 4(i) is the isolation between antenna port 10 and port 12, 4(j) is the isolation between antenna port 10 and port 13, and 4(i) is the isolation between antenna port 10 and port 14.

[0014] Figure 5These are simulation results of the radiation characteristics of antenna port one at a frequency of 1.35 GHz in this embodiment of the invention. Among them, 5(a) is the gain pattern in the xoz plane, 5(b) is the axial ratio pattern in the xoz plane, 5(c) is the three-dimensional gain pattern, and 5(d) is the three-dimensional axial ratio pattern.

[0015] Figure 6 The following are simulation results of the radiation characteristics of antenna port one at a frequency of 3.5 GHz in this embodiment of the invention. 6(a) is the gain pattern in the xoz plane, 6(b) is the axial ratio pattern in the xoz plane, 6(c) is the three-dimensional gain pattern, and 6(d) is the three-dimensional axial ratio pattern.

[0016] Figure 7 The following are simulation results of the radiation characteristics of antenna port one at a frequency of 4GHz in this embodiment of the invention. 7(a) is the gain pattern in the xoz plane, 7(b) is the axial ratio pattern in the xoz plane, 7(c) is the three-dimensional gain pattern, and 7(d) is the three-dimensional axial ratio pattern.

[0017] Figure 8 These are simulation results of the radiation characteristics of antenna port one at a frequency of 4.5 GHz in this embodiment of the invention. 8(a) is the gain pattern in the xoz plane, and 8(b) is the axial ratio pattern in the xoz plane. 8(c) is the three-dimensional gain pattern, and 8(d) is the three-dimensional axial ratio pattern.

[0018] Figure 9 These are simulation results of the radiation characteristics of the antenna port 10 at a frequency of 1.35 GHz in this embodiment of the invention. 9(a) is the gain pattern in the xoz plane, 9(b) is the axial ratio pattern in the xoz plane, 9(c) is the three-dimensional gain pattern, and 9(d) is the three-dimensional axial ratio pattern.

[0019] Figure 10 The following are simulation results of the radiation characteristics of the antenna port 10 at a frequency of 3.5 GHz in this embodiment of the invention. 10(a) is the gain pattern in the xoz plane, 10(b) is the axial ratio pattern in the xoz plane, 10(c) is the three-dimensional gain pattern, and 10(d) is the three-dimensional axial ratio pattern.

[0020] Figure 11 The following are simulation results of the radiation characteristics of the antenna port 10 at a frequency of 4GHz in this embodiment of the invention: 11(a) gain pattern in the xoz plane, 11(b) axial ratio pattern in the xoz plane, 11(c) three-dimensional gain pattern, and 11(d) three-dimensional axial ratio pattern.

[0021] Figure 12The following are simulation results of the radiation characteristics of the antenna port 10 at a frequency of 4.5 GHz in this embodiment of the invention. 12(a) is the gain pattern in the xoz plane, 12(b) is the axial ratio pattern in the xoz plane, 12(c) is the three-dimensional gain pattern, and 12(d) is the three-dimensional axial ratio pattern.

[0022] Reference numerals: 1 is a monopole antenna element; 2 is the dielectric substrate of the monopole antenna array; 3 is the annular metal reflector ground plane of the monopole antenna array; 4 is the gap between monopole antenna array elements; 5 is the metal coupling plate between monopole antenna array elements; 6 is the radiator of the monopole antenna element; 7 is the notch of the monopole antenna element radiator; 8 is the copper foil ground plane of the feed CPW of the monopole antenna element radiator; 9 is the feed CPW section connected to the monopole antenna element radiator; 10 is the continuously tapered section of the feed CPW of the monopole antenna element radiator; 11 is the uniform structure section of the feed CPW and coaxial line connection of the monopole antenna element radiator; 12 is a monopole mirror Vivaldi antenna element; 13 is the cylindrical metal carrier of the monopole mirror Vivaldi antenna element array; 14 is the absorbing material on the outside of the cylindrical metal carrier of the monopole mirror Vivaldi antenna element array; 15 is the monopole mirror Vivaldi antenna element array. The following structures are listed: 16 is the absorbing material inside the cylindrical metal carrier; 17 is the loading medium structure with a larger thickness; 18 is the pure metal monopole mirror Vivaldi radiator structure with a smaller thickness; 19 is the boundary control structure of the first monopole mirror Vivaldi radiator; 20 is the boundary control structure of the second monopole mirror Vivaldi radiator; 21 is the resonant cavity of the pure metal monopole mirror Vivaldi radiator; 22 is the first cut in the metal arm of the pure metal monopole mirror Vivaldi radiator; 23 is the second cut in the pure metal monopole mirror Vivaldi radiator; 24 is the third cut in the metal arm of the pure metal monopole mirror Vivaldi radiator; 25 is the metal arm of the pure metal monopole mirror Vivaldi radiator; 26 is the coaxial feeding line; and 27 is the edge portion of the exponential curve shape of the pure metal monopole mirror Vivaldi radiator. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] This invention uses an aircraft carrier as a working platform and, based on the technical requirements of a multi-band polarization diversity passive detection radar system, proposes a composite multi-band wideband polarization diversity antenna device that employs a circumferentially closely arranged printed monopole array and a circumferentially arranged miniaturized monopole mirror Vivaldi antenna array, aiming to achieve the goal of sensing the polarization information of radiation source signals and measuring the direction of arrival.

[0025] Figure 1 The diagram shown is a schematic of the overall structure of a polarization diversity multi-band antenna array system. Figure 1 (a) is a three-dimensional structural model of a polarization diversity multi-band antenna array. Figure 1 (b) to Figure 1 (e) are the front, rear, left, and right views of the polarization diversity multi-band antenna array, respectively. It can be seen that the polarization diversity multi-band antenna array system designed in this invention uses a cylindrical carrier platform made of metal. Microwave broadband absorbing materials of different thicknesses are placed on the inner and outer sides of the cylindrical carrier. The printed monopole antenna array is located on a dielectric substrate, with the monopole antenna elements arranged closely along the circumference. The radiator of the printed monopole antenna array is located in the inner region of the cylindrical metal carrier. The miniaturized monopole mirror Vivaldi antenna array is arranged in a conformal layout along the circumference and is located in the outer region of the cylindrical carrier. The number of elements in the monopole mirror Vivaldi is the same as the number of elements in the printed monopole antenna, and the antenna elements of the two correspond one-to-one, forming polarization diversity antenna pairs with approximately orthogonal polarization.

[0026] Figure 2 The diagram shows a schematic of a circumferentially arranged CPW-fed monopole antenna system. Figure 2 (a) is a three-dimensional structural model of a CPW-fed monopole antenna array. Figure 2 (b) to Figure 2 (d) are the front view, rear view, and top view of the CPW-fed monopole antenna array, respectively. Figure 2 (e) is a rear view of the CPW-fed monopole antenna array with the circular reflector floor hidden. Figure 2 (f) is a front view of a CPW-fed monopole antenna element; Figure 2 In the diagram, 1 represents a monopole antenna element, 2 represents the dielectric substrate of the monopole antenna array, 3 represents the annular metal reflector ground plane of the monopole antenna array, 4 represents the gap between monopole antenna array elements, 5 represents the metal coupling sheet between monopole antenna array elements, 6 represents the radiator of the monopole antenna element, 7 represents the cutout of the monopole antenna element radiator, 8 represents the copper foil ground plane of the feed CPW of the monopole antenna element radiator, 9 represents the feed CPW section connected to the monopole antenna element radiator, 10 represents the continuously tapered section of the feed CPW of the monopole antenna element radiator, and 11 represents the uniform structure section of the feed CPW of the monopole antenna element radiator connected to the coaxial line.

[0027] For the installation area of ​​a circular platform antenna, this invention designs a circumferentially closely arranged printed monopole antenna array. The antenna radiator arms adopt a combination of fan-shaped rings and chamfered rectangular elements, making full use of the planar space of the circular printed dielectric substrate. The monopole radiator arms are excited by coplanar waveguides (CPWs). The CPW structure that excites the metal arms of the antenna radiators includes a region connected to the monopole radiator arms, a uniform CPW region connected to the coaxial cable for feeding, and a continuous impedance transformation section between the two. The copper foil ground plane on which the CPW feeding structure is located is trapezoidal to facilitate impedance matching with the monopole radiator arms. Multiple monopole radiator elements form a circumferentially closely arranged multi-band antenna array, forming a passive radar signal receiving antenna array with polarization. Gaps are left between the monopole radiator arm elements, and a rectangular coupling plate is set on the other side of the printed dielectric substrate to increase the electromagnetic coupling between the monopole radiator arms and improve the impedance and radiation pattern performance in the low-frequency band. A circular metal reflector structure is placed below the printed dielectric substrate where the monopole radiator array is located to control the radiation pattern of the monopole radiator array.

[0028] The characteristic impedance of a uniform CPW connected to a coaxial cable is 50 ohms. The characteristic impedance of a coplanar waveguide can be calculated using the following formula, defining variables. and Their values ​​are respectively (1) (2) In the formula: The thickness of the dielectric substrate; The width of the dielectric substrate; The width of the coplanar waveguide feed line; The gap width between the coplanar waveguide feed and the ground plane; the effective relative permittivity of the dielectric substrate is: (3) In the formula: , , , These are the first-order complete elliptic integral function and its complement, respectively, and their specific expressions are as follows: (4) The characteristic impedance of a coplanar waveguide can be expressed as: (5) Figure 3 The diagram shows a schematic of a circumferentially arranged monopole mirror Vivaldi antenna system. Figure 3(a) is a three-dimensional structural model of a single-pole mirrored Vivaldi antenna array. Figure 3 (b) to (e) are the front view, rear view, top view, and left view of a single-pole mirrored Vivaldi antenna array, respectively. Figure 3 (f) is a three-dimensional structural model of a single-pole mirrored Vivaldi antenna element. Figure 3 (g) to Figure 3 (j) are the front view, rear view, left view, and right view of a single-pole mirrored Vivaldi antenna element, respectively. Figure 3 (k) is the three-dimensional structural model of the monopole mirror Vivaldi antenna element after hiding the loaded dielectric structure. Figure 3 (l) to Figure 3 (m) are the left and right views of the monopole mirrored Vivaldi antenna element after the hidden loading dielectric structure is concealed.

[0029] exist Figure 3 In the diagram, 12 is a monopole mirror Vivaldi antenna element, 13 is the cylindrical metal carrier of the monopole mirror Vivaldi antenna element array, 14 is the absorbing material on the outer side of the cylindrical metal carrier of the monopole mirror Vivaldi antenna element array, 15 is the absorbing material on the inner side of the cylindrical metal carrier of the monopole mirror Vivaldi antenna element array, 16 is a thick loading medium structure, 17 is a pure metal monopole mirror Vivaldi radiator structure, 18 is a thin loading medium structure, 19 is the boundary control structure of the first monopole mirror Vivaldi radiator, and 20 is the second monopole mirror. Like the boundary control structure of the Vivaldi radiator, 21 is the resonant cavity of the pure metal monopole mirror Vivaldi radiator, 22 is the first cut of the metal arm of the pure metal monopole mirror Vivaldi radiator, 23 is the second cut of the pure metal monopole mirror Vivaldi radiator, 24 is the third cut of the metal arm of the pure metal monopole mirror Vivaldi radiator, 25 is the metal arm of the pure metal monopole mirror Vivaldi radiator, 26 is the coaxial line for feeding, and 27 is the edge part of the exponential curve shape of the pure metal monopole mirror Vivaldi radiator.

[0030] This invention employs a metal-structured monopole mirror Vivaldi antenna array to achieve a receiving channel approximately orthogonal to the monopole radiator, resulting in polarization diversity. Based on the mirror theory of electromagnetic fields, a metal ground plane is placed in the center region of the traditional Vivaldi antenna radiating slot. This ground plane is perpendicular to the metal sheet containing the Vivaldi antenna radiator, thus eliminating half of the radiator structure while approximately preserving the original radiation effect, achieving excellent miniaturization. In the monopole mirror Vivaldi antenna design, considering the limited installation space, rectangular metal sheet structures forming an approximate electromagnetic boundary mirror ground plane are set on the upper and lower sides of the monopole Vivaldi radiator vibrator. These metal sheet structures are perpendicular to the metal sheet region of the Vivaldi antenna radiator, and their heights differ on the upper and lower sides. Dielectric block structures with a certain dielectric constant are placed on the front and rear sides of the metal arm of the monopole Vivaldi radiator vibrator to improve the radiation efficiency of the monopole mirror Vivaldi radiator, improve impedance characteristics at low frequencies, and reduce return loss at low frequencies. The different shapes and thicknesses of the dielectric blocks on the front and rear sides increase the freedom of impedance tuning. Multiple monopole mirror Vivaldi antenna elements are arranged circumferentially to form a cylindrical conformal layout ultrawideband miniaturized antenna array. This array is used to achieve beam coverage in a specific area in front of the aircraft structure. Microwave absorbing material is placed on the inner and outer surfaces of the cylindrical metal carrier to reduce the installation height of the monopole mirror Vivaldi antennas, improve the impedance and radiation performance of the antenna array, and enhance the electromagnetic isolation performance between the polarization diversity antenna composite array.

[0031] The exponential curve equation used in the metal radiating arm of the monopolar mirror Vivaldi designed in this invention is: (6) In the formula, and According to respectively , , , and Confirmed, here. This represents the length of the straight-line slot from the origin, corresponding to the length of a conventional Vivaldi antenna compared to a monopole mirrored Vivaldi antenna. For a straight gap, the width is [value]; for an exponentially gradient gap, the width is [value]. The length of the exponentially gradient gap. The constant of the exponential curve, This refers to the width of a conventional Vivaldi antenna corresponding to a monopole mirrored Vivaldi antenna; here, we use... .

[0032] exist Figure 3 In (i), the shape of the dielectric block loaded inside the monopole mirror Vivaldi antenna is determined by parameters. , , and the thickness of the dielectric block Confirmed; the thickness of the dielectric block loaded on the outside of the monopole mirror Vivaldi antenna is... It is rectangular in shape and fills the entire surface of the metal vibrator arm of the monopole mirror Vivaldi antenna radiator.

[0033] In summary, this invention presents a multi-band polarization diversity passive detection radar antenna system. This antenna design is characterized by ease of design, simple structure, low cost, and miniaturization. While ensuring polarization isolation and radiation pattern coverage of the polarization diversity antenna, the designed antenna system exhibits stable electrical performance, convenient mechanical installation, and reliable structure, making it suitable for engineering applications. The multi-band polarization diversity passive detection radar antenna device of this invention is suitable for use in passive guidance radar, electronic reconnaissance systems, electronic jamming systems, and electronic countermeasures systems, demonstrating significant practical application value.

[0034] Example: This example designs a polarization diversity multi-band passive radar antenna system. The performance of the antenna was simulated using full-wave electromagnetic simulation software. The simulation results verify the performance of the polarization diversity multi-band passive radar antenna proposed in this invention. The simulation results of the return loss and port isolation of the polarization diversity multi-band passive radar antenna system designed in this invention are as follows: Figure 4 As shown in the figure, port 1 corresponds to one element of a printed monopole antenna, and port 10 corresponds to a monopole mirror Vivaldi antenna element that is approximately orthogonal in polarization to port 1. The designed polarization diversity multi-band composite passive radar antenna system includes 9 printed monopole antenna elements and 9 monopole mirror Vivaldi antenna elements. As can be seen from the figure, in the operating frequency range of 1.35 GHz and 4 GHz, the return loss of ports 1 and 10 of this antenna is low, allowing it to operate in passive reception mode. The isolation between ports 1 and 10 is greater than approximately 30 dB in the operating frequency region, achieving polarization diversity. For the printed monopole antenna array, the coupling between ports is strong due to the close proximity of the monopole antenna elements. The electromagnetic isolation between the monopole mirror Vivaldi antenna elements is relatively large.

[0035] Figures 5 to 8Simulation results of the radiation pattern of port 1 at operating frequencies of 1.35 GHz, 3.5 GHz, 4 GHz and 4.5 GHz are presented respectively. At each frequency, the gain pattern, axial ratio pattern, three-dimensional gain pattern and three-dimensional axial ratio pattern in the xoz plane are presented respectively. Figures 9 to 12 Simulation results of the radiation patterns of the port 10 at operating frequencies of 1.35 GHz, 3.5 GHz, 4 GHz, and 4.5 GHz are presented. For each frequency, the gain pattern, axial ratio pattern, three-dimensional gain pattern, and three-dimensional axial ratio pattern in the xoz plane are given. It can be seen that the Vivaldi antenna size can be compressed by using the monopole mirror principle, and the use of circumferentially arranged monopole antennas effectively utilizes the antenna installation space. The radiation performance of this composite array antenna is improved to a certain extent at low frequencies. The radiation patterns of both antenna polarization ports exhibit approximate linear polarization characteristics, demonstrating good polarization diversity. Near the two operating frequencies, the two polarized antenna elements have a certain beam coverage range, enabling detection of the corresponding spatial regions.

Claims

1. A miniaturized multi-band polarization diversity array antenna device, comprising a cylindrical carrier platform made of metal, characterized in that, Microwave broadband absorbing materials of different thicknesses are set on the inner and outer sides of a cylindrical carrier platform. A printed monopole antenna array is arranged closely along the circumference of the cylindrical carrier. The printed monopole antenna array contains monopole antenna elements. The radiator of the printed monopole antenna array is located in the inner region of the cylindrical metal carrier. A monopole mirror Vivaldi antenna array is arranged in a conformal layout along the circumference and is located in the outer region of the cylindrical carrier platform. The monopole mirror Vivaldi antenna array contains monopole mirror Vivaldi antenna elements. The number of monopole mirror Vivaldi antenna elements is the same as the number of printed monopole antenna elements. The antenna elements of the two are in one-to-one correspondence, forming polarization diversity antenna pairs with approximately orthogonal polarization. The printed monopole antenna unit includes a monopole antenna radiator arm comprising a front fan-shaped annular portion and a rear chamfered rectangular portion. The monopole antenna radiator arm is excited by a coplanar waveguide (CPW). The CPW structure of the excited antenna radiator arm includes a region connected to the monopole radiator arm, a uniform CPW region connected to the coaxial cable for feeding, and a continuous impedance transformation section between the two. The copper foil ground plane where the CPW feeding structure is located is trapezoidal to facilitate impedance matching with the monopole radiator arm. Multiple monopole radiator units form a circumferentially closely arranged multi-band antenna array. A passive radar signal receiving antenna array with polarization is constructed. Gaps are left between the monopole radiator element arms. A rectangular coupling plate is placed on the other side of the printed dielectric substrate to increase electromagnetic coupling between the monopole radiator element arms, improving impedance and radiation pattern performance in the low-frequency band. A circular metal reflector structure is placed below the printed dielectric substrate containing the monopole radiator array to modulate the radiation pattern of the monopole radiator array. In the monopole antenna element radiator, the characteristic impedance of the uniform CPW connected to the coaxial cable being fed is 50 ohms. The characteristic impedance of the coplanar waveguide is calculated using the following formula, defining variables... and Their values ​​are respectively (1)， (2)， In the formula: The thickness of the dielectric substrate; The width of the dielectric substrate; The width of the coplanar waveguide feed line; The gap width between the coplanar waveguide feed and the ground plane; the effective relative permittivity of the dielectric substrate is: (3)， In the formula: , , , These are the first-order complete elliptic integral function and its complement, respectively, and their specific expressions are as follows: (4)， The characteristic impedance of a coplanar waveguide is expressed as: (5)； A metal-structured monopole mirror Vivaldi antenna array achieves a receiving channel that is approximately orthogonal to the monopole radiator, resulting in polarization diversity. A metal floor is placed in the center of the traditional Vivaldi antenna radiating slot, perpendicular to the metal sheet containing the Vivaldi antenna radiator. Rectangular metal sheet structures, acting as an electromagnetic boundary mirror floor, are placed on the upper and lower sides of the monopole Vivaldi radiator. These metal sheet structures are perpendicular to the metal sheet area of ​​the Vivaldi antenna radiator, with different heights on the upper and lower sides. Dielectric blocks with different dielectric constants are placed on the front and rear sides of the metal arm of the monopole Vivaldi radiator. Multiple monopole mirror Vivaldi antenna elements are arranged circumferentially to form a cylindrical conformal layout of an ultra-wideband miniaturized antenna array, used to achieve beam coverage in a certain area in front of the aircraft structure. The exponential curve equation used for the metallic radiating arm of the monopole mirror Vivaldi antenna element is: （6）， In the formula, and according to Sure, It is a constant of the exponential curve; The shape of the dielectric block loaded inside the monopole mirror Vivaldi antenna element is determined by parameters. , , and the thickness of the dielectric block Confirmed; the thickness of the dielectric block loaded on the outside of the monopole mirror Vivaldi antenna is... It is rectangular in shape and fills the entire surface of the metal vibrator arm of the monopole mirror Vivaldi antenna radiator.

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