Large-frequency-ratio common-caliber tight coupling array antenna

Abstract

The invention provides a large-frequency-ratio common-caliber tight coupling array antenna which comprises a plurality of antenna units arranged periodically. The antenna unit comprises a high-frequency array antenna composed of a plurality of high-frequency array units and a low-frequency antenna; the low-frequency antenna comprises a second dielectric substrate and a low-frequency dipole formed by two declination low-frequency dipole arms printed on the front and back plate surfaces of the second dielectric substrate; and two U-shaped gaps and two rectangular gaps with different lengths are etched on the low-frequency dipole arm. When the high-frequency array antenna radiates, a part of incident electromagnetic waves are reflected by the declination structure and return to the high-frequency array antenna in different directions and phases, the electromagnetic waves in different directions and phases are mutually superposed and counteracted, and the other incident electromagnetic waves pass through the two U-shaped gaps and the two rectangular gaps and are radiated out. The coupling between the high-frequency array antenna and the low-frequency antenna is reduced, and compared with the prior art, the radiation performance under the condition of a large frequency ratio is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave antennas and relates to a tightly coupled array antenna, in particular to a large frequency ratio common aperture tightly coupled array antenna, which can be used in radar systems and point-to-point communication systems. Background Art

[0002] The tightly coupled array antenna is an ultra-wideband antenna that utilizes the mutual coupling effect between units by closely arranging antenna units, thereby expanding the working bandwidth of the antenna. This design concept is different from the method of avoiding the mutual coupling effect between array elements in traditional array antennas. Its working principle is based on the continuous current sheet array theory proposed by Wheeler. A continuous current can be formed on the array surface, and ultra-wideband matching is achieved through the dynamic balance of the coupling capacitance between dipoles and the inductance between dipoles and reflectors in the entire frequency band. The tightly coupled antenna consists of several structures such as short dipoles, metal reflectors, broadband baluns, and wide-angle matching layers. These components work together to achieve ultra-wideband and high-gain characteristics.

[0003] A co-aperture antenna is an antenna that allows multiple antennas of different frequency bands and polarizations to work simultaneously within the same aperture. Co-aperture antennas can achieve signal transmission in multiple frequency bands while using the same aperture. Its core advantage lies in aperture reuse, that is, it achieves coverage of multiple frequency bands without adding additional space. Combining co-aperture antennas with tightly coupled array antennas, i.e. co-aperture tightly coupled array antennas, achieves the ability to work in multiple frequency bands within the same aperture while maintaining the miniaturization and wide bandwidth characteristics of the antenna.

[0004] In 2023, S. Zhang et al. proposed a co-aperture tightly coupled array in "An Extremely Wideband Tightly Coupled Dipole Array With Shared-Aperture Configuration" published in IEEE ANTENNAS AND WIRELESS PROPAGATION. The invention adopts a structure in which the high-frequency band antenna array is deployed below the low-frequency band antenna array, achieving the same cross-sectional height characteristic of the co-aperture tightly coupled array as that of an independent low-frequency band antenna array, and a zigzag structure is designed on the low-frequency band antenna dipole arm to achieve "electromagnetic transparency" of the low-frequency band antenna array to the high-frequency band antenna, avoiding cross-band interference between antennas of the two frequency bands, and can work normally in the 0.24-0.93 GHz and 0.9-5.1 GHz frequency bands. If the frequency ratio of the high and low frequency bands is to be improved, due to the zigzag structure on the low-frequency band antenna dipole arm, a strong coupling will be generated between the low-frequency array antenna and the high-frequency array antenna, thereby affecting the radiation characteristics of the high-frequency array antenna. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to propose a large frequency ratio co-aperture tightly coupled array antenna, aiming to ensure a large frequency ratio while improving the radiation characteristics of the high frequency array antenna.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention includes a plurality of antenna units arranged periodically; the antenna unit includes a high-frequency array antenna and a low-frequency antenna composed of a plurality of high-frequency array units 1 arranged periodically; the low-frequency antenna includes a second dielectric substrate 2 and a low-frequency dipole 4 composed of two downward-tilted low-frequency dipole arms printed on the front and back surfaces of the second dielectric substrate, and a second feeding balun 5 connected to the low-frequency dipole 4; two U-shaped gaps 6 and a first rectangular notch 7 and a second rectangular notch 8 of unequal lengths are etched on the low-frequency dipole arm, and a low-frequency coupling patch 3 is printed on the back of each of the two low-frequency dipole arms to form an overlapping structure with the low-frequency dipole 4.

[0007] As an optimization, the high-frequency array unit 1 includes a metal floor 11 and a first dielectric substrate 12 fixed vertically thereto, and a first feeding balun 16; a high-frequency dipole arm is printed on the front and back surfaces of the first dielectric substrate 12 to form a high-frequency dipole 13, and a high-frequency coupling patch 14 is printed on the back of each of the two high-frequency dipole arms, and the high-frequency coupling patch 14 is connected to the metal floor 11 through a metal short-circuit line 15; the first feeding balun 16 adopts a conical structure, whose ground layer is connected to one high-frequency dipole arm, and the inner core is connected to the other high-frequency dipole arm.

[0008] As an optimization, the surface of the first dielectric substrate 12 is parallel to the second dielectric substrate 2 .

[0009] As an optimization, in the low-frequency dipole 4, the length of the first rectangular notch 7 etched on each low-frequency dipole arm is smaller than the length of the second rectangular notch 8, and the first rectangular notch 7 is close to one side of the starting end of the low-frequency dipole arm.

[0010] As an optimization, in the low-frequency dipole 4 , the first rectangular notch 7 and the second rectangular notch 8 etched on each low-frequency dipole arm are parallel, and the first rectangular notch 7 and the second rectangular notch 8 are parallel to the first dielectric substrate 12 .

[0011] As an optimization, the second feeding balun 5 adopts a conical structure, wherein the ground layer is connected to one low-frequency dipole arm, and the inner core is connected to another low-frequency dipole arm.

[0012] As an optimization, in the low-frequency dipole 4, the two U-shaped slots 6 etched on each low-frequency dipole arm have their opening directions facing one side of the end of the low-frequency dipole arm.

[0013] As an optimization, the first rectangular notch 7 is located at the upper edge of the dipole arm.

[0014] As an optimization, the second rectangular notch 8 is located at the lower edge of the dipole arm.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The two dipole arms of the low-frequency dipole on the low-frequency antenna parallel to the high-frequency array antenna of the present invention adopt a downtilt structure. When the high-frequency array antenna radiates, a portion of the incident electromagnetic waves is reflected by the downtilt structure and returns to the high-frequency array antenna in different directions and phases. These electromagnetic waves in different directions and phases are superimposed and cancel each other out, and the remaining incident electromagnetic waves are radiated through two U-shaped gaps and a first rectangular notch and a second rectangular notch of unequal lengths, thereby reducing the coupling between the high-frequency array antenna and the low-frequency antenna, and effectively improving the radiation performance under large frequency ratio conditions compared with the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 It is a structural schematic diagram of the high-frequency array unit of the present invention;

[0019] Figure 3 A comparison diagram of the active standing wave ratio of the high-frequency array antenna of the down-tilt low-frequency dipole arm of the present invention and the existing low-frequency dipole arm;

[0020] Figure 4 A comparison diagram of the active standing wave ratio of a high-frequency array antenna of the present invention between a downward-tilted low-frequency dipole arm with a slotted structure and a downward-tilted low-frequency dipole arm without a slotted structure; DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] Reference Figure 1 to Figure 3The present invention includes a plurality of antenna units arranged periodically; the antenna unit includes a high-frequency array antenna and a low-frequency antenna composed of a plurality of high-frequency array units 1 arranged periodically; the low-frequency antenna includes a second dielectric substrate 2 and a low-frequency dipole 4 composed of two downward-tilted low-frequency dipole arms printed on the front and back surfaces of the second dielectric substrate, and a second feeding balun 5 connected to the low-frequency dipole 4; two U-shaped gaps 6 and a first rectangular notch 7 and a second rectangular notch 8 of unequal lengths are etched on the low-frequency dipole arm, and a low-frequency coupling patch 3 is printed on the back of each of the two low-frequency dipole arms to form an overlapping structure with the low-frequency dipole 4. The second dielectric substrate 2 is a Rogers RT5880 dielectric plate with a thickness of 0.8 mm, a relative dielectric constant of 2.2, and a loss tangent of 0.0009; the low-frequency coupling patch 3 provides the coupling capacitance required for tight coupling; the second feeding balun 5 is a conical feeding balun to achieve impedance transformation and balanced feeding.

[0023] The high-frequency array unit 1 includes a metal floor 11 and a first dielectric substrate 12 vertically fixed thereto, and a first feeding balun 16; a high-frequency dipole arm is printed on the front and back surfaces of the first dielectric substrate 12 to form a high-frequency dipole 13, and a high-frequency coupling patch 14 is printed on the back of each of the two high-frequency dipole arms, and the high-frequency coupling patch 14 is connected to the metal floor 11 through a metal short-circuit line 15; the first feeding balun 16 adopts a conical structure, and its ground layer is connected to one high-frequency dipole arm, and the inner core is connected to the other high-frequency dipole arm. The first dielectric substrate 12 is a Rogers RT5880 dielectric plate with a thickness of 1mm, a relative dielectric constant of 2.2, and a loss tangent of 0.0009; the high-frequency coupling patch 14 provides the coupling capacitance required for tight coupling; the first feeding balun 16 is a conical feeding balun to achieve impedance transformation and balanced feeding. The metal short-circuit line 15 effectively suppresses the common-mode resonance brought by the first feeding balun 16 and broadens the bandwidth.

[0024] The first dielectric substrate 12 has a surface parallel to the second dielectric substrate 2 .

[0025] In the low-frequency dipole 4, the length of the first rectangular notch 7 etched on each low-frequency dipole arm is smaller than the length of the second rectangular notch 8, and the first rectangular notch 7 is close to one side of the starting end of the low-frequency dipole arm.

[0026] In the low-frequency dipole 4 , the first rectangular notch 7 and the second rectangular notch 8 etched on each low-frequency dipole arm are parallel, and the first rectangular notch 7 and the second rectangular notch 8 are parallel to the first dielectric substrate 12 .

[0027] The second feeding balun 5 adopts a conical structure, wherein the ground layer is connected to one low-frequency dipole arm, and the inner core is connected to another low-frequency dipole arm.

[0028] The low-frequency dipole 4 has two U-shaped slots 6 etched on each low-frequency dipole arm, and its opening direction faces one side of the end of the low-frequency dipole arm.

[0029] The first rectangular notch 7 is located at the upper edge of the dipole arm. The second rectangular notch 8 is upward along the lower edge of the dipole arm.

[0030] The second rectangular notch 8 is located at the lower edge of the dipole arm.

[0031] The following is a further description of the technical effects of the present invention in conjunction with simulation experiments:

[0032] 1. Simulation conditions and contents:

[0033] The present invention uses the simulation software ANSYS Electronics Desktop v21 to compare and simulate the active standing waves of the high-frequency array antenna of the down-tilt low-frequency dipole arm of the present invention and the existing low-frequency dipole arm, and the active standing waves of the high-frequency array antenna of the down-tilt low-frequency dipole arm with a slot structure and the down-tilt low-frequency dipole arm without a slot structure. The results are as follows: Figure 3 and 4 shown.

[0034] 2. Analysis of simulation results:

[0035] Reference Figure 3 The active standing wave ratio of the high-frequency array antenna with the existing straight low-frequency dipole arm deteriorates significantly at 3.5GHz, 6.7GHz and 8GHz, and reaches about 8 at 6.7GHz; the active standing wave ratio of the high-frequency array antenna with the existing upward low-frequency dipole arm deteriorates significantly at 3.2GHz, 4.2GHz and 8GHz, and exceeds 8 at 3.2GHz and 8GHz. The active standing wave ratio of the high-frequency array antenna with the downward-tilted low-frequency dipole arm of the present invention is significantly improved, reaching only about 4 at 2.5GHz, which indicates that the coupling between the low-frequency antenna and the high-frequency antenna array is minimal, and the radiation performance of the high-frequency antenna array is the best.

[0036] Reference Figure 4 In order to further optimize the radiation performance of the high-frequency array antenna, a slotted structure is used on the down-tilted low-frequency dipole arm. Compared with the down-tilted low-frequency dipole arm without the slotted structure, the active standing wave ratio of the high-frequency array antenna provided with the down-tilted low-frequency dipole arm of the present invention is significantly improved, the high points at 2.7GHz, 3.6GHz and 6GHz are eliminated, and it is kept below 3 in the range of 2.17-10.22GHz.

Claims

1. A high-frequency ratio common-aperture tightly coupled array antenna, comprising a plurality of periodically arranged antenna units; the antenna units comprise a high-frequency array antenna and a low-frequency antenna composed of a plurality of periodically arranged high-frequency array units (1); characterized in that; The low-frequency antenna comprises a second dielectric substrate (2), a low-frequency dipole (4) composed of two downward-tilted low-frequency dipole arms printed on the front and back surfaces of the second dielectric substrate, and a second feeding balun (5) connected to the low-frequency dipole (4); two U-shaped gaps (6) and a first rectangular notch (7) and a second rectangular notch (8) of unequal lengths are etched on the low-frequency dipole arms, and a low-frequency coupling patch (3) is printed on the back of each of the two low-frequency dipole arms to form an overlapping structure with the low-frequency dipole (4).

2. The antenna according to claim 1, characterized in that The high-frequency array unit (1) comprises a metal floor (11) and a first dielectric substrate (12) vertically fixed thereto, and a first feeding balun (16); a high-frequency dipole arm is printed on each of the front and back surfaces of the first dielectric substrate (12) to form a high-frequency dipole (13); a high-frequency coupling patch (14) is printed on each of the back surfaces of the two high-frequency dipole arms; the high-frequency coupling patch (14) is connected to the metal floor (11) via a metal short-circuit line (15); the first feeding balun (16) adopts a conical structure, wherein the grounding layer is connected to one high-frequency dipole arm, and the inner core is connected to the other high-frequency dipole arm.

3. The antenna according to claim 2, characterized in that: The first dielectric substrate (12) has a plate surface parallel to the second dielectric substrate (2).

4. The antenna according to claim 1, characterized in that: The low-frequency dipole (4), wherein the length of the first rectangular notch (7) etched on each low-frequency dipole arm is smaller than the length of the second rectangular notch (8), and the first rectangular notch (7) is close to one side of the starting end of the low-frequency dipole arm.

5. The antenna according to claim 4, characterized in that: The low-frequency dipole (4) is characterized in that the first rectangular notch (7) and the second rectangular notch (8) etched on each low-frequency dipole arm are parallel, and the first rectangular notch (7) and the second rectangular notch (8) are parallel to the first dielectric substrate (12).

6. The antenna according to claim 4, characterized in that: The second feeding balun (5) adopts a conical structure, wherein the ground layer is connected to one low-frequency dipole arm, and the inner core is connected to another low-frequency dipole arm.

7. The antenna according to claim 4, characterized in that: The low-frequency dipole (4) has two U-shaped slots (6) etched on each low-frequency dipole arm, and its opening direction faces one side of the end of the low-frequency dipole arm.

8. The antenna according to claim 4, characterized in that: The first rectangular notch (7) is located at the upper edge of the dipole arm.

9. The antenna according to claim 4, characterized in that: The second rectangular notch (8) is located at the lower edge of the dipole arm.

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