A dual-frequency circularly polarized common-aperture antenna with broadside and conical radiation patterns

Abstract

The present invention relates to a dual-frequency circularly polarized common-aperture antenna with side-firing and conical radiation patterns, comprising a top metal layer, an intermediate metal layer, a metal backplane, a high-frequency feeding probe, a low-frequency feeding probe, a first substrate, a second substrate and a metal via; the top metal layer is located on the upper surface of the first substrate, the intermediate metal layer is located on the upper surface of the second substrate, and the high-frequency feeding probe penetrates the first substrate and the second substrate for feeding; the metal via penetrates the first substrate to connect the top metal layer and the intermediate metal layer together; the low-frequency feeding probe penetrates the second substrate and is directly connected to the intermediate metal layer. The invention integrates a low-frequency microstrip patch antenna and a high-frequency substrate integrated waveguide slot antenna to realize a microwave millimeter wave common-aperture antenna under the same aperture; the high-frequency antenna adopts a feeding structure and a radiation structure integrated method to achieve size reduction under the premise of ensuring circularly polarized radiation; it has the advantages of small space occupation, high aperture reuse ratio, simple structure and high integration.

Description

Technical Field

[0001] The invention belongs to the technical field of antennas, and in particular relates to a dual-frequency circularly polarized common-aperture antenna with broadside and conical radiation patterns. Background Art

[0002] With the rapid development of communication technology, spectrum resources in the microwave band are becoming increasingly scarce. Millimeter wave communication has the advantages of high data rate, wide spectrum range, high reliability and low latency, and has good application prospects for high-speed data transmission systems. However, millimeter wave transmission has large loss and limited transmission distance. Therefore, it is of great practical significance to design a dual-frequency co-aperture antenna that covers both microwave and millimeter wave bands to make up for the shortcomings of millimeter wave communication and reduce the size and volume of the antenna.

[0003] For moving vehicles or flying drones, in order to meet the communication needs in fast-moving situations, the antenna needs to have different beam patterns. The use of reconfigurable technology can switch different patterns through radio frequency switches, thereby changing the radiation direction of the antenna to meet the communication needs of mobile carriers in different directions. The invention patent of CN 115566431A proposes a multi-diopter electric small antenna with reconfigurable pattern, but the antenna only radiates linearly polarized waves and cannot receive waves from any direction like a circularly polarized antenna. In addition, the use of radio frequency switches to achieve pattern switching will cause problems such as complex structure and increased size. CN 115621712A proposes a dual-frequency circularly polarized common-aperture antenna, but the maximum radiation direction of the antenna in the two frequency bands is in the normal direction, which cannot solve the problem of single beam coverage of mobile carriers. Summary of the invention

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide a dual-frequency circularly polarized common-aperture antenna with both broadside and conical radiation patterns. The invention integrates a low-frequency microstrip patch antenna and a high-frequency substrate integrated waveguide slot antenna together to realize a microwave millimeter wave common-aperture antenna with the same aperture; the high-frequency antenna adopts a feeding structure and a radiation structure integrated method to achieve size reduction while ensuring circularly polarized radiation; the overall antenna does not use additional integrated circuit components to achieve different beam radiation patterns. It is the first time in all publicly reported documents that a dual-frequency circularly polarized common-aperture antenna with both broadside and conical radiation patterns has been proposed, which has the advantages of small footprint, high aperture reuse ratio, simple structure, and high integration.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A dual-frequency circularly polarized common-aperture antenna with side-firing and conical radiation patterns comprises a top metal layer, an intermediate metal layer, a metal back plate, a high-frequency feeding probe, a low-frequency feeding probe, a first substrate, a second substrate and a metal via; the top metal layer is located on the upper surface of the first substrate and serves as a radiation structure of the high-frequency antenna; the intermediate metal layer is located on the upper surface of the second substrate and serves as a metal floor of the high-frequency antenna; the high-frequency antenna is fed by a high-frequency feeding probe that penetrates the first substrate and the second substrate; the metal via penetrates the first substrate to connect the top metal layer and the intermediate metal layer together to form a closed substrate integrated waveguide structure; the low-frequency microstrip patch antenna uses the intermediate metal layer as a radiation structure, the metal back plate serves as a metal floor, and shares the intermediate metal layer structure with the high-frequency antenna; the low-frequency antenna is fed by a low-frequency feeding probe that penetrates the second substrate and is directly connected to the intermediate metal layer.

[0007] Furthermore, the metal vias divide the metal layer into four circular cavities of the same size, and the opening sizes of the circular cavities can be controlled by changing the positions of the metal vias in the horizontal and vertical directions to fine-tune the impedance matching of the high-frequency antenna.

[0008] Furthermore, four circular grooves of the same size and width are etched inside the circular cavity to form a 2×2 high-frequency antenna array, which is fed by a high-frequency feeding probe.

[0009] Furthermore, the circular cavity is additionally provided with a perturbation hole, so that each individual circular cavity realizes circularly polarized radiation in the side-firing direction.

[0010] Furthermore, in order to enable the low-frequency antenna to achieve circularly polarized radiation, a pair of long rectangular grooves and short rectangular grooves of unequal lengths are etched on the metal backplane, and the two types of rectangular grooves are located on the diagonal of the metal backplane. By changing the length and position of the long rectangular grooves and the short rectangular grooves, the low-frequency antenna obtains an orthogonal degenerate mode, and the two modes have equal amplitudes and a phase difference of 90°, so that circularly polarized radiation can be achieved in the side-firing direction, thereby obtaining a side-firing circularly polarized radiation pattern.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] In view of the shortcomings of the current common aperture antenna, which is large in size and has a low aperture reuse rate, the present invention adopts the design concept of structural reuse to achieve a dual-frequency antenna design under the same aperture without increasing the size of the antenna. The antenna occupies a small space and has a high aperture reuse ratio.

[0013] In view of the shortcomings of the current reconfigurable antenna, such as complex structure and low integration, the present invention breaks through the method of realizing different directional patterns with traditional reconfigurable technology, and adopts a design scheme of co-aperture of substrate integrated waveguide antenna and microstrip patch antenna. There is no need to introduce additional integrated circuit components such as RF switch diodes, and the antenna structure is simple and highly integrated.

[0014] In order to solve the problem of signal reception when the mobile carrier moves rapidly, the present invention proposes to integrate microwave and millimeter wave frequency band antennas into one antenna aperture. The frequency ratio of the two bands is large, and both realize circularly polarized radiation, and can receive waves from any direction. The antenna has side-fire and conical radiation patterns in the two frequency bands respectively, which solves the beam coverage problem of the mobile carrier. This is the first time in all public reports that an antenna with this function has been proposed.

[0015] In view of the problem that the current millimeter-wave antenna radiation structure and feeding network are designed separately, resulting in a complex structure and a high profile, the antenna proposed in the present invention uses a substrate-integrated waveguide circular cavity as a radiation structure in the millimeter-wave frequency band, and adopts a central feeding method. The circular cavity also serves as a feeding network for power distribution. Therefore, no additional power divider is required, thereby realizing the multiplexing of the radiation structure and the feeding structure. It has the advantages of compact structure, low profile, simple feeding, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A three-dimensional diagram of the antenna of the present invention.

[0017] Figure 2 It is a side view of the antenna of the present invention.

[0018] Figure 3 It is a front plan view of the antenna of the present invention.

[0019] Figure 4 It is a back plan view of the antenna of the present invention.

[0020] Figure 5 This is the curve of S parameter variation with frequency when the low-frequency microstrip patch antenna works in the microwave frequency band.

[0021] Figure 6 This is the curve of S parameter variation with frequency when the high-frequency substrate integrated waveguide slot antenna works in the millimeter wave frequency band.

[0022] Figure 7 This is the curve of the axial ratio changing with frequency when the low-frequency microstrip patch antenna works in the microwave frequency band.

[0023] Figure 8 This is the curve of the axial ratio changing with frequency when the high-frequency substrate integrated waveguide slot antenna works in the millimeter wave frequency band.

[0024] Fig. 9 This is the far-field radiation pattern of the low-frequency microstrip patch antenna when φ=0° operates at 4.9GHz.

[0025] Fig.10 This is the far-field radiation pattern of the low-frequency microstrip patch antenna with φ=90° working at 4.9GHz.

[0026] Fig.11This is the far-field radiation pattern of the high-frequency substrate integrated waveguide slot antenna when φ=0° operates at 20GHz.

[0027] Fig.12 This is the far-field radiation pattern of the high-frequency substrate integrated waveguide slot antenna when θ=45° operates at 20GHz. DETAILED DESCRIPTION

[0028] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0029] Figure 1 and Figure 2 As shown, the antenna proposed in the present invention includes a top metal layer 100, an intermediate metal layer 200, a metal backplane 300, a high-frequency feeding probe 301, a low-frequency feeding probe 302, a first substrate 400, and a second substrate 401. The high-frequency substrate integrated waveguide slot antenna is composed of a top metal layer 100, an intermediate metal layer 200 and a first substrate 400, and is fed by a high-frequency feeding probe 301 penetrating the first substrate 400 and the second substrate 401. The top metal layer 100 is located on the upper surface of the first substrate 400 as a radiation structure of the high-frequency antenna; the intermediate metal layer 200 is located on the upper surface of the second substrate 401 as a metal floor of the high-frequency antenna. At the same time, the entire high-frequency antenna structure can be regarded as a radiation patch of a low-frequency antenna structure, which is located on the upper surface of the second substrate 401 and constitutes a low-frequency patch antenna structure together with the metal backplane 300 and the second substrate 401. The low-frequency antenna is fed by a low-frequency feeding probe 302 penetrating the second substrate 401. Through this structural reuse method, high aperture utilization is achieved.

[0030] like Figure 3As shown, the metal via 101 divides the top metal layer 100 into four circular cavities 102 of the same size. The opening size of the circular cavity 102 can be controlled by changing the position of the metal via in the horizontal and vertical directions to fine-tune the impedance matching of the high-frequency antenna. Four circular grooves 103 of the same size and width are etched in the circular cavity 102, and by adding a perturbation hole 104, each individual circular cavity 102 can achieve circular polarization radiation in the side-firing direction. The four circular cavities 102 form a 2×2 high-frequency antenna array, and are fed by a high-frequency feeding probe 301 located at the center of the top metal layer 100 that penetrates the first substrate 400 and the second substrate 401. Since the four circular cavities 102 are symmetrical relative to the center of the top metal layer 100, the two circular cavities 102 located in the diagonal direction obtain equal-amplitude and anti-phase feeding signals by rotating the perturbation hole 104 counterclockwise around the center by 0°, 90°, 180°, and 270°. Therefore, although each circular cavity 102 has an edge-firing circular polarization radiation pattern, the 2×2 high-frequency antenna array composed of four circular cavities 102 presents a conical circular polarization radiation pattern.

[0031] Due to the central feeding effect of the high-frequency feeding probe 301, the energy is evenly distributed to the four circular cavities 102 through the feeding probe. At this time, the top metal layer not only serves as a high-frequency radiation structure, but also as a high-frequency feeding structure, realizing structural reuse and effectively reducing the antenna size and cross-section.

[0032] like Figure 4 As shown, the high-frequency substrate integrated waveguide slot antenna is stacked on the upper surface of the second substrate 401, which can be regarded as the radiation structure of the low-frequency antenna. It forms a low-frequency patch antenna together with the metal back plate 300, and is fed through the second substrate 401 through the low-frequency feeding probe 302. In order to make the low-frequency antenna realize circular polarization radiation, a pair of long rectangular grooves 303 and short rectangular grooves 304 of unequal lengths are etched on the metal back plate 300. The two types of rectangular grooves are located on the diagonal of the metal back plate 300. By changing the length and position of the long rectangular grooves 303 and the short rectangular grooves 304, the low-frequency antenna obtains an orthogonal degenerate mode, and the two modes have equal amplitudes and a phase difference of 90°, so that circular polarization radiation can be realized in the broadside direction, thereby obtaining a broadside circular polarization pattern.

[0033] Figure 5 The S parameter curve of the low-frequency microstrip patch antenna working in the microwave frequency band varies with frequency. The antenna works at a frequency of 4.78-5.04GHz in the microwave frequency band, and the impedance bandwidth is 5.3%.

[0034] Figure 6 This is the S parameter variation curve of the high-frequency substrate integrated waveguide slot antenna when working in the millimeter wave band. The antenna works at a frequency of 19.58-20.36GHz in the millimeter wave band, and the impedance bandwidth is 3.9%.

[0035] Figure 7 The curve of the axial ratio value of the low-frequency microstrip patch antenna working in the microwave frequency band varies with frequency. When the antenna is at φ=0°, θ=0°, the frequency range where the axial ratio is lower than 3dB is 4.86-4.94GHz, and the axial ratio bandwidth is 1.6%.

[0036] Figure 8 This is the curve of the axial ratio value of the high-frequency substrate integrated waveguide slot antenna working in the millimeter wave frequency band. When the antenna is at φ=0° and θ=45°, the frequency range where the axial ratio is lower than 3dB is 19.92-20.31GHz, and the axial ratio bandwidth is 1.9%.

[0037] Fig. 9 This is the far-field radiation pattern of the low-frequency microstrip patch antenna when φ=0° when it works at 4.9GHz. At this time, the antenna realizes the side-beam circular polarization radiation mode.

[0038] Fig.10 This is the far-field radiation pattern of the low-frequency microstrip patch antenna when φ=90° is working at 4.9GHz. At this time, the antenna realizes the side-beam circular polarization radiation mode.

[0039] Fig.11 This is the far-field radiation pattern of the high-frequency substrate integrated waveguide slot antenna when φ=0° when operating at 20GHz. At this time, the antenna realizes conical beam circular polarization radiation mode.

[0040] Fig.12 This is the far-field radiation pattern of the high-frequency substrate integrated waveguide slot antenna when θ=45° is working at 20GHz. At this time, the antenna is in the omnidirectional circular polarization radiation mode in the maximum radiation direction of the conical beam.

[0041] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A dual-frequency circularly polarized common aperture antenna with broadside and conical radiation patterns, characterized in that: It includes a top metal layer, an intermediate metal layer, a metal backplane, a high-frequency feeding probe, a low-frequency feeding probe, a first substrate, a second substrate and a metal via; the top metal layer is located on the upper surface of the first substrate and serves as a radiation structure of the high-frequency antenna; the intermediate metal layer is located on the upper surface of the second substrate and serves as a metal floor of the high-frequency antenna; the high-frequency antenna is fed by the high-frequency feeding probe penetrating the first substrate and the second substrate; The metal via penetrates the first substrate to connect the top metal layer and the middle metal layer together to form a closed substrate integrated waveguide structure; the low-frequency microstrip patch antenna uses the middle metal layer as a radiation structure, the metal backplane is used as a metal floor, and the middle metal layer structure is shared with the high-frequency antenna. The low-frequency antenna is fed by a low-frequency feeding probe, and the low-frequency feeding probe penetrates the second substrate and is directly connected to the middle metal layer; the metal via divides the top metal layer into four circular cavities of the same size, and the opening size of the circular cavity is controlled by changing the position of the metal via in the horizontal and vertical directions to provide a good radiation effect on the high-frequency antenna. The impedance matching of the antenna is fine-tuned; four circular grooves of the same size and width are etched inside the circular cavity to form a 2×2 high-frequency antenna array, and are fed by a high-frequency feeding probe; the circular cavity is added with a perturbation hole so that each individual circular cavity can achieve circular polarization radiation in the side-firing direction; the high-frequency feeding probe is located at the center of the top metal layer; the four circular cavities are symmetrical with respect to the center of the top metal layer, and the two circular cavities located in the diagonal direction obtain equal-amplitude and anti-phase feeding signals by rotating the perturbation hole counterclockwise around the center by 0°, 90°, 180°, and 270°.

2. A dual-frequency circularly polarized co-aperture antenna with broadside and conical radiation patterns as claimed in claim 1, characterized in that: The metal back plate is etched with a pair of long rectangular grooves and short rectangular grooves of unequal lengths, and the two types of rectangular grooves are located on the diagonal of the metal back plate. By changing the length and position of the long rectangular grooves and the short rectangular grooves, the low-frequency antenna obtains an orthogonal degenerate mode, and the two modes have equal amplitudes and a phase difference of 90°.

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