Broadband high-gain circularly polarized filtering array antenna based on stacked circular cross-slot patches

Abstract

The application discloses a kind of wideband high-gain circularly polarized filter array antennas based on stacked circular cross-slot patch, belong to antenna technical field;The antenna includes four stacked circular cross-slot patch circularly polarized array antenna units, four one-to-two power division phase shift feed networks and one one-to-four power division phase shift feed network;In order to improve the impedance bandwidth and radiation gain of antenna, circular patch with cross-shaped slot is provided on the antenna unit;The frequency point of the antenna of the application is 3.5 GHz, and the dielectric substrate adopts Taconic TLX-8;Array antenna is composed of 4 antenna units, the size is 1.51λ×1.51λ×0.15λ, the frequency band range is 2.5GHz-4.5GHz, and the gain at 3.85GHz frequency point is 14.9dBi.The antenna of the application has great advantages in wide frequency band and gain etc..

Description

Technical Field

[0001] This patent belongs to the field of antenna technology and relates to a broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches. Background Technology

[0002] With the trend towards high integration in modern wireless communication systems, RF front-end equipment and antenna systems are also facing higher demands for multifunctionality and miniaturization. Filtered antennas, as a collaborative design of antennas and filters, can suppress interference signals and significantly reduce the load on filters after the transmitting / receiving antennas. Therefore, the development of filtered antennas is of great significance in modern communication engineering.

[0003] With the rapid development of wireless communication technology, circularly polarized antennas have received increasing attention. Compared to linearly polarized antennas, they offer advantages such as reducing polarization mismatch, enhancing multipath interference suppression, and improving system sensitivity between transmitters and receivers. Circularly polarized microstrip patch antennas inherently suffer from narrow bandwidth. To achieve broadband performance, researchers have developed various methods, such as increasing substrate thickness and reducing the dielectric constant of the substrate. This invention utilizes a method of loading stacked parasitic patches and etching cross-shaped slots on the radiating patches to broaden the bandwidth. Furthermore, to obtain higher antenna gain and a wider axial ratio bandwidth, resulting in better antenna radiation directivity, a 2×2 antenna array is fabricated.

[0004] Therefore, this invention proposes a broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches. Summary of the Invention

[0005] The purpose of this invention is to propose a broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches. The use of stacked patches and sequential rotation feeding technology can effectively broaden the axial ratio bandwidth, enhance circular polarization characteristics, and improve the antenna gain.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches, the structure of which includes, from top to bottom: a first layer of metal sheet (1), a first layer of dielectric substrate (2), a second layer of metal sheet (3), a second layer of dielectric substrate (4), a metal pillar (5), a third layer of metal sheet (6), a third layer of dielectric substrate (7), and a fourth layer of metal sheet (8); Furthermore, the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches is characterized in that: the antenna includes four stacked circular cross-slotted patch circularly polarized array antenna elements, four 1-to-2 power-dividing phase-shifting feed networks, and one 1-to-4 power-dividing phase-shifting feed network; the four stacked circular cross-slotted patch circularly polarized array antenna elements serve as a radiating structure to introduce two radiation nulls, thereby achieving filtering functionality without additional circuitry; the four 1-to-2 power-dividing phase-shifting feed networks provide each of the four stacked circular cross-slotted patch circularly polarized array antenna elements with a 90° phase difference and the same amplitude; the 1-to-4 power-dividing phase-shifting feed network provides each of the four 1-to-2 power-dividing phase-shifting feed networks with 90° sequential phase differences and the same amplitude; the stacked patch circularly polarized array antenna is a planar structure and is placed along the xoy plane; Furthermore, the unit structure consists of a stacked patch (12) with a first cross groove (11) etched in the first metal sheet (1), a second metal sheet (3), metal pillars (5), and a third metal sheet (6); the first metal sheet (1) and the second metal sheet (3) have a 7.0 mm air gap to form a magnetic coupling to introduce a high-frequency resonant mode and a radiation null point; the second metal sheet (3) consists of a driving patch (31) and four arc-shaped patches (32) with central openings; the four arc-shaped patches (32) with central openings are evenly distributed around the driving patch (31); the metal pillars (5) are a group with a diameter of 2.0 mm and a height of 4.0 mm. The metal connecting rod is connected to the circular holes of the four arc-shaped patches (32), which can be regarded as a vertically open split ring resonator. They are electrically coupled to the driving patch (31) and introduce a low-frequency resonant mode and a radiation zero, thereby achieving the filtering function without additional circuitry. The third layer metal sheet (6) is set as a square patch (61) and a rectangular patch (62) with metal holes on both sides. The square patch (61) has a second cross groove (63) for aperture coupling. The rectangular patch (62) with metal holes on both sides is located in the second cross groove (63) and is connected to the one-to-two power-division phase-shifting feed network. Furthermore, the four one-to-two power-dividing phase-shifting feed networks are composed of a first polygonal metal line (81), a second polygonal metal line (82), a third polygonal metal line (83), and a fourth polygonal metal line (84). The first polygonal metal line (82) is provided with a first "T"-shaped branch line (811) and a metallized hole (812) to improve impedance matching performance and impedance bandwidth. The first polygonal metal line (81) and the rectangular patch (62) are connected through the metallized hole (812). By adjusting the branch length of the first polygonal metal line (81), two input signals with a phase difference of 90° and the same amplitude are provided. The energy is coupled to the driving patch (31) through the cross slot (63) and then radiates a left-hand circularly polarized wave. The second polygonal metal line (82), the third polygonal metal line (83), the fourth polygonal metal line (84), and the first polygonal metal line (81) have the same structure and function. Furthermore, the one-to-four power-dividing phase-shifting feed network is composed of polygonal metal lines (85); the polygonal metal lines (85) are composed of a fifth “T”-shaped branch line (851), a sixth “T”-shaped branch line (852) and a seventh “T”-shaped branch line (853) to improve impedance matching performance; by adjusting the branch length of the polygonal metal lines (85), four input signals with phase differences of 90° and the same amplitude are provided for the first “T”-shaped branch line (811), the second “T”-shaped branch line (821), the third “T”-shaped branch line (831) and the fourth “T”-shaped branch line (841), so that a sequential rotating feed network with phases increasing by 90° at the four output ports can be obtained. Furthermore, the antenna has four elements arranged in a clockwise rotation. The 1-to-4 power-dividing phase-shifting feed network is connected to four 1-to-2 power-dividing feed networks to provide the four antenna elements with feeds that are sequentially 90° out of phase and have the same amplitude, in order to expand the axial ratio bandwidth, enhance the circular polarization characteristics, and improve the antenna gain. Furthermore, the first dielectric substrate (2) is configured as a circular structure, the second dielectric substrate (4) is configured as a circular structure, and the third dielectric substrate (7) is configured as a square structure; the materials of the first dielectric substrate (2), the second dielectric substrate (4), and the third dielectric substrate (7) are all Taconic TLX-8, with a dielectric constant of 2.55, a loss angle of 0.0017, and a thickness of 1.0 mm for each of the three dielectric substrates; Furthermore, the size of the single-element antenna is 0.75λ × 0.75λ × 0.15λ, and the size of the 4-element array antenna is 1.51λ × 1.51λ × 0.15λ. The frequency range of the single-element antenna with a return loss of less than -10 dB is 3.19 GHz - 4.06 GHz, the frequency range of the 3 dB axial ratio bandwidth is 3.36 GHz - 3.93 GHz, and the highest gain reaches 9.4 dBi. The frequency range of the 4-element array antenna with a return loss of less than -10 dB is 3.18 GHz - 4.12 GHz, the frequency range of the 3 dB axial ratio bandwidth is 3.23 GHz - 4.03 GHz, and the gain at the 3.85 GHz frequency point reaches 14.9 dBi.

[0007] Compared with the prior art, the present invention has the following advantages: (1) The broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches proposed in this invention has wide bandwidth characteristics. The radiation structure adopts stacked circular cross-slotted parasitic patches and vertical split ring structure, realizing a third-order filter gain response with two near-frequency radiation zeros. It can not only broaden the impedance bandwidth, but also achieve the filtering function without additional circuitry. (2) The broadband high-gain circular polarization filter array antenna based on stacked circular cross slotted patches proposed in this invention has high gain characteristics. The antenna adopts a sequential rotation feeding technology, which realizes the feeding of 4 antenna elements with a phase difference of 90° and the same amplitude, improves cross polarization, enhances main polarization, thereby expanding the axial ratio bandwidth, enhancing the circular polarization characteristics, improving the radiation gain, and meeting the high gain design requirements. (3) The broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches proposed in this invention has low loss characteristics. The filtering performance is directly realized through the antenna itself, avoiding the increase in volume and insertion loss caused by introducing filters, and reducing structural complexity.

[0008] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0009] Figure 1 is a structural diagram of the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches according to the present invention; Figure (a) is a structural diagram of a single-element array antenna, and Figure (b) is a structural diagram of a 4-element array antenna. Figure 2 shows the reflection coefficient curve of the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches according to the present invention; Figure (a) shows the reflection coefficient curve of a single-element array, and Figure (b) shows the reflection coefficient curve of a 4-element array antenna. Figure 3 shows the gain curve of the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches according to the present invention; Figure (a) is the gain curve of a single-element array, and Figure (b) is the gain curve of a 4-element array antenna. Figure 4 shows the E-plane radiation pattern of the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches of the present invention at a frequency of 3.5 GHz; wherein Figure (a) is the radiation pattern of a single-element array and Figure (b) is the radiation pattern of a 4-element array. Detailed Implementation

[0010] Figure 1 shows the structure of the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches according to the present invention. The antenna includes four stacked circular cross-slotted patch circularly polarized array antenna elements, four 1-to-2 power-division phase-shifting feed networks, and one 1-to-4 power-division phase-shifting feed network. The four stacked circular cross-slotted patch circularly polarized array antenna elements serve as a radiating structure, introducing two radiation nulls to achieve filtering functionality without additional circuitry. The four 1-to-2 power-division phase-shifting feed networks provide phase distribution to the four stacked circular cross-slotted patch circularly polarized array antenna elements respectively. The RF energy with a phase difference of 90° and the same amplitude is provided by the 1-to-4 power-dividing phase-shifting feed network to provide RF energy with a phase difference of 90° and the same amplitude to the four 1-to-2 power-dividing phase-shifting feed networks; the stacked circular cross-slotted patch circular polarized array antenna includes, from top to bottom, a first layer of metal sheet (1), a first layer of dielectric substrate (2), a second layer of metal sheet (3), a second layer of dielectric substrate (4), a metal pillar (5), a third layer of metal sheet (6), a third layer of dielectric substrate (7), and a fourth layer of metal sheet (8); the stacked patch circular polarized array antenna is a planar structure, and along xoy The unit structure is composed of a stacked patch (12) with a first cross groove (11) etched in the first metal sheet (1), a second metal sheet (3), metal pillars (5), and a third metal sheet (6); the first metal sheet (1) and the second metal sheet (3) have a 7.0 mm air gap to form a magnetic coupling to introduce a high-frequency resonant mode and a radiation null point; the second metal sheet (3) is composed of a driving patch (31) and four arc-shaped patches (32) with central openings; the four arc-shaped patches (32) with central openings are evenly distributed around the driving patch (31); the metal pillars (5) are a set with a diameter of 2.0 mm and a height of 4.0 mm. The metal connecting rods are connected to the circular holes of the four arc-shaped patches (32), which can be regarded as a vertically open split ring resonator. They are electrically coupled to the driving patch (31) and introduce a low-frequency resonant mode and a radiation zero, thereby achieving the filtering function without additional circuitry. The third layer metal sheet (6) is set as a square patch (61) and a rectangular patch (62) with metal holes on both sides. The square patch (61) has a second cross groove (63) for aperture coupling. The rectangular patch (62) with metal holes on both sides is located in the second cross groove (63) and is connected to the one-to-two power-division phase-shifting feed network. The four one-to-two power-division phase-shifting feed networks are composed of a first polygonal metal line (81), a second polygonal metal line (82), a third polygonal metal line (83), and a fourth polygonal metal line (84). The first polygonal metal line (81) is provided with a first "T"-shaped branch line (811) and a metallized hole (812) to improve impedance matching performance and impedance bandwidth.The first polygonal metal line (81) and the rectangular patch (62) are connected through a metallized hole (812). By adjusting the branch length of the first polygonal metal line (81), two input signals with a 90° phase difference and the same amplitude are provided. The energy is coupled to the driving patch (31) through the second cross slot (63) and then radiates a left-hand circularly polarized wave. The second polygonal metal line (82), the third polygonal metal line (83), the fourth polygonal metal line (84) and the first polygonal metal line (81) have the same structure and function. The one-to-four power-dividing phase-shifting feed network is composed of polygonal metal lines (85). (85) Composed of a fifth “T”-shaped branch line (851), a sixth “T”-shaped branch line (852), and a seventh “T”-shaped branch line (853), it is used to improve impedance matching performance; by adjusting the branch length of the polygonal metal wire (85), it is used to provide four input signals with phase differences of 90° and the same amplitude for the first “T”-shaped branch line (811), the second “T”-shaped branch line (821), the third “T”-shaped branch line (831), and the fourth “T”-shaped branch line (841), so that a sequential rotating feed network with phases increasing by 90° for the four output ports can be obtained; the number of antenna elements is 4. The four antenna elements are arranged in a clockwise rotation. The one-to-four power-dividing phase-shifting feed network is connected to four one-to-two power-dividing feed networks to provide the four antenna elements with feeds that are 90° out of phase and have the same amplitude, in order to expand the axial ratio bandwidth, enhance the circular polarization characteristics, and improve the antenna gain. The first layer dielectric substrate (2) of the stacked circular cross-slotted patch circular polarization filter array antenna element is set as a circular structure, the second layer dielectric substrate (4) is set as a circular structure, and the third layer dielectric substrate (7) is set as a square structure. The materials of the first layer dielectric substrate (2), the second layer dielectric substrate (4), and the third layer dielectric substrate (7) are all Taconic TLX-8 with a dielectric constant ε. r The wavelength is 2.55, the loss angle is 0.0017, and the thickness of each of the three dielectric substrates is 1.0 mm; the size of the single antenna is 0.75λ × 0.75λ × 0.15λ, and the size of the 4-element array antenna is 1.51λ × 1.51λ × 0.15λ.

[0011] Figure 2 shows the reflection coefficient curve of the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches according to the present invention. It can be seen that the frequency range of the return loss below -10 dB for the antenna element is 3.19 GHz - 4.06 GHz, and the frequency range of the return loss below -10 dB for the 4-element array antenna is 3.18 GHz - 4.12 GHz. The simulation results verify that the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches has broadband characteristics.

[0012] Figure 3 shows the gain curve of the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches according to the present invention. It can be seen that the peak gains of the single-element antenna and the 4-element array antenna can reach 9.4 dBi and 14.9 dBi, respectively. The simulation results verify that the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches has good radiation gain characteristics.

[0013] Figure 4 shows the E-plane radiation pattern of the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches at 3.5 GHz. As can be seen, the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches has a good gain pattern at the operating frequency.

[0014] As can be seen from the above, the broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches of the present invention has the characteristics of wide bandwidth, high gain and low loss.

Claims

1. A broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches, characterized in that: The antenna includes four stacked circular cross-slotted patch circular polarized filter array antenna elements, four 1-to-2 power-dividing phase-shifting feed networks, and one 1-to-4 power-dividing phase-shifting feed network; the stacked circular cross-slotted patch circular polarized filter array antenna includes, from top to bottom, a first layer metal sheet (1), a first layer dielectric substrate (2), a second layer metal sheet (3), a second layer dielectric substrate (4), a metal pillar (5), a third layer metal sheet (6), a third layer dielectric substrate (7), and a fourth layer metal sheet (8); the antenna element includes a first layer metal sheet (1), a second layer metal sheet (3), a metal pillar (5), and a third layer metal sheet (6); the first layer metal sheet (1) is the upper metal structure of the antenna element, and the first layer metal sheet (1) includes stacked patches (12), which are the patch pattern parts in the first layer metal sheet (1) used for stacking radiation, and are etched with the first cross slot (11); a 7.0 mm gap is provided between the first layer metal sheet (1) and the second layer metal sheet (3). mm air gap; the second layer metal sheet (3) is composed of a driving patch (31) and four arc-shaped patches (32) with central openings; the four arc-shaped patches (32) with central openings are evenly distributed around the driving patch (31); the metal pillar (5) is a set of 2.0 mm in diameter and 4 mm in height.A 0 mm metal connecting rod is connected to the circular holes of four arc-shaped patches (32); the third layer metal sheet (6) is configured as a square patch (61) and a rectangular patch (62) with metal holes on both sides; the square patch (61) has a second cross groove (63); the rectangular patch (62) with metal holes on both sides is located in the second cross groove (63) and is connected to the one-to-two power-division phase-shifting feed network; the antenna unit introduces a radiation null point and forms a filtering response through the cooperation of the stacked patch (12) with the first cross groove (11) etched in the first layer metal sheet (1), the second layer metal sheet (3), the metal pillar (5) and the third layer metal sheet (6); the four one-to-two power-division phase-shifting feed networks are composed of a first polygonal metal line (81), a second polygonal metal line (82), a third polygonal metal line (83) and a fourth polygonal metal line (84); the first polygonal metal line (81) is configured as a square patch (61) and a rectangular patch (62) with metal holes on both sides; the square patch (61) has a second cross groove (63) etched in the first layer metal sheet (1), a second layer metal sheet (3), a metal pillar (5) and a third layer metal sheet (6); the first polygonal metal line (81) is configured as a square patch (61) and a rectangular patch (62) with metal holes on both sides; the rectangular patch (62) with metal holes on both sides is located in the second cross groove (63) and is connected to the circular holes of four arc-shaped patches (32); the third layer metal sheet (6) has a second cross groove (11) etched in the first layer metal sheet (1), a second layer metal sheet (3), a metal pillar (5) and a third layer metal sheet (6); the first polygonal metal line (81) is configured as a square patch (61) and a rectangular patch (62) with metal holes on both sides; the third layer metal sheet (62) has a second cross The system includes a first "T"-shaped branch line (811) and a metallized hole (812); the first polygonal metal line (81) and the rectangular patch (62) are connected through the metallized hole (812); the second polygonal metal line (82), the third polygonal metal line (83), the fourth polygonal metal line (84) and the first polygonal metal line (81) have the same structure; the one-to-two power-dividing phase-shifting feed network provides two input signals with a 90° phase difference and the same amplitude to the rectangular patch (62) through the first polygonal metal line (81), the first "T"-shaped branch line (811) and the metallized hole (812) to achieve circular polarization feeding; the one-to-four power-dividing phase-shifting feed network is composed of polygonal metal lines (85); the polygonal metal lines (85) are composed of a fifth "T"-shaped branch line (851), a sixth "T"-shaped branch line (852) and a seventh "T"-shaped branch line (853).

2. The broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches according to claim 1, characterized in that: The four antenna elements are arranged in a clockwise rotation. By adjusting the branch length of the polygonal metal wire (85), the first "T"-shaped branch line (811), the second "T"-shaped branch line (821), the third "T"-shaped branch line (831), and the fourth "T"-shaped branch line (841) are fed with a phase difference of 90° and the same amplitude, so as to expand the axial ratio bandwidth, enhance the circular polarization characteristics and improve the array antenna gain.

3. The broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches according to claim 1, characterized in that: The first dielectric substrate (2) is set as a circular structure, the second dielectric substrate (4) is set as a circular structure, and the third dielectric substrate (7) is set as a square structure; the first dielectric substrate (2), the second dielectric substrate (4) and the third dielectric substrate (7) are all made of Taconic TLX-8, with a dielectric constant of 2.55, a loss tangent of 0.0017, and a thickness of 1.0 mm for each of the three dielectric substrates.

4. The broadband high-gain circularly polarized filter array antenna based on stacked circular cross-slotted patches according to claim 1, characterized in that: The antenna element size is 0.75λ×0.75λ×0.15λ, and the array antenna composed of four antenna elements has a size of 1.51λ×1.51λ×0.15λ. The antenna element has a return loss below -10 dB in the frequency range of 3.19 GHz-4.06 GHz, a 3 dB axial ratio bandwidth in the frequency range of 3.36 GHz-3.93 GHz, and a maximum gain of 9.4 dBi. The array antenna composed of four antenna elements has a return loss below -10 dB in the frequency range of 3.18 GHz-4.12 GHz, a 3 dB axial ratio bandwidth in the frequency range of 3.23 GHz-4.03 GHz, and a gain of 14.9 dBi at the 3.85 GHz frequency point.

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