A large frequency ratio co-aperture tightly coupled array antenna

Abstract

The application provides a large frequency ratio co-aperture tightly coupled 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 composed of two downwardly-inclined low-frequency dipole arms printed on the front and back surfaces of the low-frequency antenna; and two U-shaped slots and two rectangular notches with different lengths are etched on the low-frequency dipole arms. When the high-frequency array antenna radiates, a part of incident electromagnetic waves is reflected through the downwardly-inclined structure and returns to the high-frequency array antenna in different directions and phases; the electromagnetic waves in different directions and phases are superimposed and cancelled with each other; and the remaining incident electromagnetic waves are radiated out through the two U-shaped slots and the two rectangular notches, so that the coupling between the high-frequency array antenna and the low-frequency antenna is reduced, and the radiation performance under the condition of a large frequency ratio is effectively improved compared with the prior art.

Description

TECHNICAL FIELD

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

[0002] The tightly coupled array antenna is a kind of ultra-wideband antenna, which expands the working bandwidth of the antenna by closely arranging the antenna elements to utilize the mutual coupling effect between the elements. This design idea is different from the method of avoiding mutual coupling effect between the elements in the traditional array antenna. Its working principle is based on the continuous current sheet array theory proposed by Wheeler. The array surface can form a continuous current, and the dynamic balance between the coupling capacitance between the dipoles and the inductance between the dipoles and the reflector plate realizes the ultra-wideband matching in the entire frequency band. The tightly coupled antenna is composed of several structures such as short dipoles, metal reflector, wideband balun, wide-angle matching layer, etc. These components work together to achieve ultra-wideband and high gain characteristics.

[0003] The shared-aperture antenna refers to an antenna that allows multiple antennas of different frequency bands and different polarizations to work simultaneously in the same aperture plane. The shared-aperture antenna can realize signal transmission of multiple frequency bands at the same time using the same aperture. Its core advantage lies in aperture multiplexing, i.e. realizing coverage of multiple frequency bands without increasing additional space. Combining the shared-aperture antenna and the tightly coupled array antenna, i.e. the shared-aperture tightly coupled array antenna, realizes the working ability of multiple frequency bands in the same aperture, while maintaining the miniaturization and wide bandwidth characteristics of the antenna.

[0004] In 2023, S. Zhang et al. published "An Extremely Wideband Tightly Coupled Dipole Array With Shared-Aperture Configuration" in IEEE ANTENNAS AND WIRELESS PROPAGATION. This invention adopts the structure of deploying the high-frequency antenna array below the low-frequency antenna array, realizing the characteristic that the profile height of the shared-aperture tightly coupled array is the same as that of the independent low-frequency antenna array. The low-frequency antenna array is designed with a zigzag structure on the dipole arm, realizing "electromagnetic transparency" of the high-frequency antenna, avoiding cross-band interference between the two frequency band antennas, and enabling normal operation in the 0.24-0.93GHz and 0.9-5.1GHz frequency bands. If the frequency ratio of high and low frequency bands is to be improved, due to the zigzag structure on the low-frequency antenna dipole arm, strong coupling will occur between the low-frequency array antenna and the high-frequency array antenna, thereby affecting the radiation characteristics of the high-frequency array antenna. SUMMARY

[0005] The present application aims to overcome the defects of the prior art, and proposes a large frequency ratio co-aperture tightly coupled array antenna, which aims to ensure a large frequency ratio while improving the radiation characteristics of a high-frequency array antenna.

[0006] To achieve the above object, the technical scheme adopted by the present application comprises a plurality of antenna units arranged periodically; the antenna units comprise a high-frequency array antenna composed of a plurality of high-frequency array units 1 arranged periodically and a low-frequency antenna; the low-frequency antenna comprises a second dielectric substrate 2 and a low-frequency dipole 4 composed of two downwardly inclined low-frequency dipole arms printed on the front and back surfaces of the second dielectric substrate, and a second feed balun 5 connected with the low-frequency dipole 4; the low-frequency dipole arms are etched with two U-shaped slots 6 and first and second rectangular notches 7 and 8 of different lengths, and the back surfaces of the two low-frequency dipole arms are each printed with a low-frequency coupling patch 3, forming an overlapping structure with the low-frequency dipole 4.

[0007] As an optimization, the high-frequency array unit 1 comprises a metal ground plate 11 and a first dielectric substrate 12 fixed vertically thereto, and a first feed balun 16; the front and back surfaces of the first dielectric substrate 12 are each printed with a high-frequency dipole arm, forming a high-frequency dipole 13, and the back surfaces of the two high-frequency dipole arms are each printed with a high-frequency coupling patch 14 connected with the metal ground plate 11 through a metal short-circuit line 15; the first feed balun 16 adopts a tapered structure, with its ground layer connected with one high-frequency dipole arm and its inner core connected with the other high-frequency dipole arm.

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

[0009] As an optimization, 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 beginning end of the low-frequency dipole arm.

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

[0011] As an optimization, the second feed balun 5 adopts a tapered structure, with its ground layer connected with one low-frequency dipole arm and its inner core connected with the other low-frequency dipole arm.

[0012] As an optimization, the low-frequency dipole 4, wherein 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 optimization, the first rectangular notch 7 is located at the upper edge of the dipole arm.

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

[0015] Compared with the prior art, the present application 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 adopt the downward tilt structure, when the high-frequency array antenna radiates, a part of the incident electromagnetic waves is reflected through the downward tilt structure, and returns to the high-frequency array antenna in different directions and phases, the electromagnetic waves in different directions and phases are superimposed and offset, and the remaining incident electromagnetic waves are radiated through the two U-shaped slots and the first rectangular notch and the second rectangular notch with different lengths, thereby reducing the coupling between the high-frequency array antenna and the low-frequency antenna, and effectively improving the radiation performance under the condition of large frequency ratio compared with the prior art. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0019] Figure 3 It is a comparison chart of the active standing wave ratio of the high-frequency array antenna of the downward tilt type low-frequency dipole arm of the present application and the existing low-frequency dipole arm;

[0020] Figure 4 It is a comparison chart of the active standing wave ratio of the high-frequency array antenna of the downward tilt type low-frequency dipole arm provided with a slotted structure of the present application and the downward tilt type low-frequency dipole arm without the slotted structure; DETAILED DESCRIPTION

[0021] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0022] Reference Figures 1-3The application comprises a plurality of antenna units arranged periodically; the antenna units comprise high-frequency array antennas composed of a plurality of high-frequency array units 1 arranged periodically and low-frequency antennas; the low-frequency antennas comprise a second dielectric substrate 2 and low-frequency dipoles 4 composed of two downward low-frequency dipole arms printed on the front and back surfaces of the second dielectric substrate, and a second feed balun 5 connected with the low-frequency dipoles 4; the low-frequency dipole arms are etched with two U-shaped slots 6 and first and second rectangular notches 7 and 8 of different lengths, and the back surfaces of the two low-frequency dipole arms are each printed with a low-frequency coupling patch 3, forming an overlapping structure with the low-frequency dipoles 4. The second dielectric substrate 2 is Rogers RT5880 dielectric plate material 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 coupling capacitance required for tight coupling; and the second feed balun 5 is a tapered feed balun, realizing impedance transformation and balanced feed.

[0023] The high-frequency array unit 1 comprises a metal ground plate 11, a first dielectric substrate 12 fixed vertically with the metal ground plate 11, and a first feed balun 16; the front and back surfaces of the first dielectric substrate 12 are each printed with a high-frequency dipole arm, forming a high-frequency dipole 13, and the back surfaces of the two high-frequency dipole arms are each printed with a high-frequency coupling patch 14 connected with the metal ground plate 11 through a metal short-circuit line 15; the first feed balun 16 adopts a tapered structure, with a ground layer connected with one high-frequency dipole arm and an inner core connected with the other high-frequency dipole arm. The first dielectric substrate 12 is Rogers RT5880 dielectric plate material with a thickness of 1 mm, a relative dielectric constant of 2.2 and a loss tangent of 0.0009; the high-frequency coupling patch 14 provides coupling capacitance required for tight coupling; and the first feed balun 16 is a tapered feed balun, realizing impedance transformation and balanced feed. The metal short-circuit line 15 effectively suppresses common-mode resonance caused by the first feed balun 16, widening the bandwidth.

[0024] The front and back surfaces of the first dielectric substrate 12 are parallel to the second dielectric substrate 2.

[0025] 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 beginning end of the low-frequency dipole arm.

[0026] The low-frequency dipole 4, wherein 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 feed balun 5 adopts a tapered structure, with a ground layer connected with one low-frequency dipole arm and an inner core connected with the other low-frequency dipole arm.

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

[0029] The first rectangular notch 7 is located on 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 on the lower edge of the dipole arm.

[0031] The technical effects of the present application are further described below in combination with simulation experiments:

[0032] 1. Simulation conditions and contents:

[0033] The simulation software ANSYS Electronics Desktop v21 is used to compare and simulate the active standing wave of the high-frequency array antenna of the present application, the active standing wave of the high-frequency array antenna of the existing low-frequency dipole arm, and the active standing wave of the high-frequency array antenna of the low-frequency dipole arm with a slotted structure and the low-frequency dipole arm without a slotted structure, and the results are shown in Figure 3 and 4 .

[0034] 2. Analysis of simulation results:

[0035] Referring to Figure 3 , the active standing wave ratio of the high-frequency array antenna of the existing flat low-frequency dipole arm is significantly deteriorated at 3.5 GHz, 6.7 GHz and 8 GHz, and reaches about 8 at 6.7 GHz; the active standing wave ratio of the high-frequency array antenna of the existing upward low-frequency dipole arm is significantly deteriorated at 3.2 GHz, 4.2 GHz and 8 GHz, and exceeds 8 at 3.2 GHz and 8 GHz. The active standing wave ratio of the high-frequency array antenna of the low-frequency dipole arm of the present application is significantly improved, and only reaches about 4 at 2.5 GHz, 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 best.

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

Claims

1. A high-ratio common-aperture tightly coupled array antenna, comprising a plurality of periodically arranged antenna elements; the antenna elements comprising a high-frequency array antenna and a low-frequency antenna composed of a plurality of periodically arranged high-frequency array elements (1); characterized in that; The low-frequency antenna includes a second dielectric substrate (2) and a low-frequency dipole (4) composed of two downward-sloping low-frequency dipole arms printed on the front and back surfaces of the second dielectric substrate, and a second feed balun (5) connected to the low-frequency dipole (4); two U-shaped slots (6) and a first rectangular notch (7) and a second rectangular notch (8) of unequal length 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, forming 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) includes a metal ground plane (11) and a first dielectric substrate (12) fixed perpendicularly thereto, as well as a first feed 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), and a high-frequency coupling patch (14) is printed on the back of each of the two high-frequency dipole arms. The high-frequency coupling patch (14) is connected to the metal ground plane (11) through a metal short circuit (15); the first feed balun (16) adopts a conical structure, and its ground layer is connected to one high-frequency dipole arm, and its 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 surface parallel to the second dielectric substrate (2).

4. The antenna according to claim 1, characterized in that, The low-frequency dipole (4) has a first rectangular notch (7) etched on each low-frequency dipole arm, the length of which is less than the length of the second rectangular notch (8), and the first rectangular notch (7) is located on one side near the beginning of the low-frequency dipole arm.

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

6. The antenna according to claim 4, characterized in that, The second feed balun (5) adopts a conical structure, with its ground layer connected to one low-frequency dipole arm and its inner core 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 slits (6) etched on each low-frequency dipole arm, with their openings facing 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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