A broadband circularly polarized patch antenna with a compact size

Abstract

The present invention discloses a broadband circularly polarized patch antenna with a compact size, comprising: a dielectric substrate; a driven patch, a first coupling patch and a second coupling patch. All three patches are right-angled triangles, and the three are adjacent and arranged at intervals on the dielectric substrate. The driven patch and the first coupling patch are electromagnetically coupled to form a circular polarization axial ratio zero point, and the first coupling patch and the second coupling patch are electromagnetically coupled to form another circular polarization axial ratio zero point. Three rows of metallized vias are formed on the dielectric substrate, and the three rows of metallized vias are respectively electrically connected to the driven patch, the first coupling patch and the second coupling patch; a ground plane, and the ground plane is arranged on the second surface of the dielectric substrate. The technical solution of the present invention can meet the requirements of a compact structure and a large bandwidth for a circularly polarized antenna. Under the same dielectric profile, the circular polarization axial ratio bandwidth is doubled compared with that of a chamfered patch.

Description

Technical Field

[0001] The present invention relates to the field of microwave communication technologies, and particularly to a compact-size broadband circularly polarized patch antenna. Background Art

[0002] Compared with linearly polarized antennas, circularly polarized antennas can overcome problems such as polarization mismatch, multipath effect, and channel crosstalk that occur during signal transmission. Compact-size broadband circularly polarized antennas have been applied in many wireless communication systems. In related technologies, the main methods for implementing a compact and broadband circularly polarized patch antenna are as follows.

[0003] First, a broadband power divider and phase shifter feeding network is adopted. By using a Wilkinson power divider and a Schiffman phase shifter, a broadband phase shifter feeding network is designed to feed rectangular slots radiating vertically polarized and horizontally polarized waves respectively, obtaining a circularly polarized operating bandwidth exceeding 80%. However, there are two drawbacks to achieving broadband circular polarization through the feeding network. On the one hand, the complex feeding network will greatly increase the overall size of the antenna, which is not conducive to miniaturization. On the other hand, the feeding network will generate certain board losses, reducing the radiation efficiency and actual gain of the antenna, and the board losses will increase with the increase of frequency. This limits the application of broadband circularly polarized antennas designed by the feeding network method in mobile terminals and limits the application of such antennas in high-frequency bands.

[0004] Second, circular polarization is achieved in a single-feed form. By using an L-shaped probe feeding technology and a U-shaped slotted slot loading, a circularly polarized bandwidth of 14% can be achieved. However, the profile of this antenna is as high as 0.2 times the free-space wavelength. And through a single-feed circular polarization based on a short-circuit loaded 1 / 4 square patch and a slotted slot loading, an extremely small-size circular polarization is achieved, but the circularly polarized operating bandwidth under the low-profile condition is only 1.1%.

[0005] In view of this, it is necessary to further improve the current compact-size broadband circularly polarized antenna. Summary of the Invention

[0006] To solve the above-mentioned at least one technical problem, the main object of the present invention is to provide a compact-size broadband circularly polarized patch antenna.

[0007] To achieve the above object, a technical solution adopted by the present invention is: providing a compact-size broadband circularly polarized patch antenna, including:

[0008] A dielectric substrate having opposite first and second surfaces;

[0009] A driving patch, a first coupling patch and a second coupling patch, wherein the driving patch, the first coupling patch and the second coupling patch are all right-angled triangles, and the three are adjacent and arranged at intervals on the first surface of the dielectric substrate. The driving patch is electromagnetically coupled with the first coupling patch, and the first coupling patch is electromagnetically coupled with the second coupling patch. A row of metallized vias is provided on one side of the dielectric substrate corresponding to the driving patch, the first coupling patch and the second coupling patch, and the three rows of metallized vias are electrically connected to the driving patch, the first coupling patch and the second coupling patch respectively;

[0010] A ground plane, which is arranged on the second surface of the dielectric substrate.

[0011] Optionally, the driving patch and the first coupling antenna are symmetrically arranged, and the two rows of metallized vias are orthogonally arranged;

[0012] The first coupling antenna and the second coupling antenna are symmetrically arranged, and the two rows of metallized vias are orthogonally arranged;

[0013] The driving patch and the second coupling antenna are centrosymmetrically arranged, and the two rows of metallized vias are arranged side by side.

[0014] Optionally, the distance between the driving patch and the first coupling patch is less than the distance between the first coupling patch and the second coupling patch.

[0015] Optionally, the distance between adjacent metallized vias is equidistant. The distance between adjacent metallized vias in the driving patch is greater than the distance between adjacent metallized vias in the second coupling patch, and the distance between adjacent metallized vias in the second coupling patch is greater than the distance between adjacent metallized vias in the first coupling patch.

[0016] Optionally, it further includes a feeding structure composed of a metal probe and the outer conductor of an SMA connector. The metal probe is arranged on the dielectric substrate, and one end of the metal probe is electrically connected to the driving patch, and the other end is arranged to avoid the ground plane; the outer conductor of the SMA connector is electrically connected to the ground plane.

[0017] Optionally, the thickness of the dielectric substrate is about 0.01 - 0.1 times the vacuum wavelength.

[0018] Optionally, the radiation side lengths of the driving patch and the coupling patch are 1 / 4 of the dielectric wavelength at the resonant frequency.

[0019] The technical solution of the present invention mainly includes a dielectric substrate, a driving patch, a first coupling patch and a second coupling patch. Among them, the driving patch and the two coupling patches are right-angled triangles. Three rows of metallized vias corresponding to the driving patch and the two coupling patches are provided on the dielectric substrate, and the three rows of metallized vias are electrically connected to the driving patch and the two coupling patches respectively. Three modes with equal amplitudes, orthogonal polarization in pairs and a phase difference of 90° in pairs are generated through the electromagnetic coupling of the driving patch and the two coupling patches, forming two circular polarization axial ratio zeros to achieve broadband circular polarization. In addition, the driving patch and the coupling patches are both loaded with metallized vias, and the size of the radiation side length is smaller than that of the traditional square patch antenna. When the driving patch and the first coupling patch and the first coupling patch and the second coupling patch are coupled to form circular polarization, the overall antenna area size is reduced by more than 15% compared with the traditional square patch antenna, meeting the design requirements of miniaturization, and can also expand the axial ratio bandwidth of the antenna. Under the same dielectric profile, the circular polarization axial ratio bandwidth of the antenna is doubled compared with that of the beveled patch antenna. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0021] Figure 1 It is a top view of a compact-size broadband circularly polarized patch antenna according to an embodiment of the present invention;

[0022] Figure 2 It is a front view of a compact-size broadband circularly polarized patch antenna according to an embodiment of the present invention;

[0023] Figure 3 It is an isometric side view of a compact-size broadband circularly polarized patch antenna according to an embodiment of the present invention;

[0024] Figure 4 It is a curve of the axial ratio of a compact-size broadband circularly polarized patch antenna according to an embodiment of the present invention changing with frequency;

[0025] Figure 5 It is a curve of the axial ratio of a compact-size broadband circularly polarized patch antenna according to an embodiment of the present invention changing with frequency;

[0026] Figure 6 It is the cross-sectional pattern of φ = 0° and φ = 90° at the 1.52 GHz frequency point of a compact-size broadband circularly polarized patch antenna according to an embodiment of the present invention;

[0027] Figure 7The cross-sectional radiation patterns at φ = 0° and φ = 90° of the compact-sized broadband circularly polarized patch antenna according to an embodiment of the present invention at the frequency of 1.54 GHz;

[0028] Figure 8 The cross-sectional radiation patterns at φ = 0° and φ = 90° of the compact-sized broadband circularly polarized patch antenna according to an embodiment of the present invention at the frequency of 1.57 GHz.

[0029] The realization of the objectives, functional features, and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] It should be noted that the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments may be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0032] Different from the structural design of small-sized circularly polarized patch antennas in the related art, although it can reduce the size of the antenna to a certain extent, most of them face problems such as large size and narrow axial ratio bandwidth, and it is difficult to meet the design requirements of miniaturization and integration of communication systems. This solution proposes a compact-sized broadband circularly polarized patch antenna, aiming to reduce the antenna size, broaden the axial ratio bandwidth, and improve the antenna performance. The specific structure of the compact-sized broadband circularly polarized patch antenna is as follows in the following embodiments.

[0033] Please refer to Figures 1 to 3 , Figure 1 The top view of the compact-sized broadband circularly polarized patch antenna according to an embodiment of the present invention; Figure 2 The front view of the compact-sized broadband circularly polarized patch antenna according to an embodiment of the present invention; Figure 3Isometric side view of a broadband circularly polarized patch antenna with a compact size according to an embodiment of the present invention. In the embodiment of the present invention, the broadband circularly polarized patch antenna with a compact size is applied to a microwave communication system. The broadband circularly polarized patch antenna with a compact size includes:

[0034] A dielectric substrate 6 having opposite first and second surfaces;

[0035] A driven patch 1, a first coupling patch 2, and a second coupling patch 3. The driven patch 1, the first coupling patch 2, and the second coupling patch 3 are all right-angled triangles. The three are adjacent and spaced apart on the first surface of the dielectric substrate 6. The driven patch 1 is electromagnetically coupled to the first coupling patch 2, and the first coupling patch 2 is electromagnetically coupled to the second coupling patch 3. A row of metallized vias 4 is provided on one side of the dielectric substrate 6 corresponding to the driven patch 1, the first coupling patch 2, and the second coupling patch 3. The three rows of the metallized vias 4 are electrically connected to the driven patch 1, the first coupling patch 2, and the second coupling patch 3 respectively;

[0036] A ground plane 7 provided on the second surface of the dielectric substrate 6.

[0037] Specifically, the dielectric substrate 6 mainly bears the driven patch 1, the first coupling patch 2, and the second coupling patch 3. The metal probe 5 is the inner conductor of an SMA connector, and the ground plane 7 is printed on the second surface of the dielectric substrate 6. The driven patch 1, the first coupling patch 2, and the second coupling patch 3 are specifically isosceles right-angled triangles. The driven patch 1 is adjacent to and spaced apart from the first coupling patch 2, and the first coupling patch 2 is spaced apart from the second coupling patch 3. The electrical coupling between the driven patch 1 and the first coupling patch 2 can generate two orthogonally polarized modes. The coupling model between the two patches can be equivalent to the circuit model of a J-transformer. By changing the patch spacing, patch size, and the number of metallized vias 4, the coupling coefficient can be adjusted. Thus, the two orthogonally polarized modes can be adjusted to have equal amplitude and a phase difference of 90°, forming a circular polarization axial ratio zero point to achieve broadband circular polarization; the first coupling patch 2 is electromagnetically coupled to the second coupling patch 3, and a third mode can be generated through the coupling. These three modes can be regarded as two pairs of orthogonally polarized modes. Similarly, the coupling model between the patches can be equivalent to the circuit model including two J-transformers. By changing the patch spacing, patch size, and the number of metallized vias 4, the coupling coefficient can be adjusted. When these three modes have equal amplitude and a phase difference of 90° in sequence, a circular polarization with two axial ratio zero points can be obtained. The radiation side length of a single patch loaded with metallized vias 4 is reduced by at least half compared to the side length of a traditional square patch antenna, making the overall antenna area size reduced by more than 15% compared to a traditional square patch cut-corner circularly polarized antenna.

[0038] The present invention uses a triangular patch, and the resonant size is smaller than that of a rectangular patch; a short - circuit structure is introduced, and it operates in a half - mode resonance state, and the resonant size is further reduced to half of that of a conventional triangular patch. Compared with a traditional rectangular patch antenna, the size of a single triangular patch unit is reduced by more than 50%. Secondly, the antenna itself simultaneously serves as a power - dividing and phase - shifting network without the need for an external circuit; the phase - shifting mechanism is different from that of a traditional single - fed circular polarization. The phase shift is generated by coupling, and the amount of phase shift is determined by the type and strength of the coupling. Three radiation units can generate two axial - ratio zeros, achieving broadband characteristics at an extreme size.

[0039] Specifically, the driving patch 1 and the first coupled antenna are symmetrically arranged, and two rows of the metallized vias 4 are orthogonally arranged; the first coupled antenna and the second coupled antenna are symmetrically arranged, and two rows of the metallized vias 4 are orthogonally arranged; the driving patch 1 and the second coupled antenna are centrosymmetrically arranged, and two rows of the metallized vias 4 are arranged side by side.

[0040] Specifically, the distance between the driving patch 1 and the first coupled patch 2 is less than the distance between the first coupled patch 2 and the second coupled patch 3.

[0041] Specifically, the distance between adjacent metallized vias 4 is equidistant. The distance between adjacent metallized vias 4 in the driving patch 1 is greater than the distance between adjacent metallized vias 4 in the second coupled patch 3, and the distance between adjacent metallized vias 4 in the second coupled patch 3 is greater than the distance between adjacent metallized vias 4 in the first coupled patch 2.

[0042] In this embodiment, a triangular patch is used, and the resonant size is smaller than that of a rectangular patch; a short - circuit structure is introduced, and it operates in a half - mode resonance state, and the resonant size is further reduced to half of that of a conventional triangular patch. Compared with a traditional rectangular patch antenna, the size is reduced by more than 50%. More specifically, three patches are used. Among them, the driving patch and the first coupled patch form a circular - polarization axial - ratio zero, and the first coupled patch and the second coupled patch form a second circular - polarization axial - ratio zero. Finally, two axial - ratio zeros in the band realize broadband characteristics. In addition, the antenna itself simultaneously serves as a power - dividing and phase - shifting network without the need for an external circuit; the phase - shifting mechanism is different from that of a traditional single - fed circular polarization. The phase shift is generated by coupling, and the amount of phase shift is determined by the type and strength of the coupling.

[0043] Among them, the distance between each row of the metallized vias 4 is equidistant. The number of the metallized vias 4 is multiple, and the specific number can be designed according to actual requirements. The distance between adjacent metallized vias 4 is equal.

[0044] Specifically, it further includes a feeding structure composed of a metal probe 5 and the outer conductor 8 of an SMA connector. The metal probe 5 is disposed on the dielectric substrate 6, and one end of the metal probe 5 is electrically connected to the driving patch 1, while the other end is arranged to avoid the ground plane 7. The outer conductor 8 of the SMA connector is electrically connected to the ground plane 7. Among them, a round hole is formed in the ground plane 7 corresponding to the position of the metal probe 5, and the other end of the metal probe 5 avoids the round hole. In this embodiment, the other end of the metal probe 5 is located in the round hole, but the diameter of the metal probe 5 is smaller than the aperture of the round hole, and the metal probe 5 is insulated from the inner wall of the round hole to prevent short circuit. It can be understood that in order to avoid the contact between the metal probe 5 and the inner wall of the round hole, an insulating layer can also be provided on the inner wall of the round hole to avoid their contact. Further, the other end of the metal probe 5 is coaxially and concentrically arranged with the round hole. When the metal probe 5 is coaxially and concentrically arranged with the round hole, the distance between the metal probe 5 and the inner wall of the round hole is the largest. When the diameter of the metal probe 5 is small enough, contact can be effectively avoided without setting an insulating layer on the inner wall of the round hole. It can be understood that in order to avoid their contact, an insulating layer can also be considered to be provided at the end of the metal probe 5 extending into the round hole.

[0045] The material of the above-mentioned dielectric substrate 6 is Rogers RT5880. This Rogers RT5880 board is a PTFE composite material reinforced with micro glass fiber, which has the characteristics of low dielectric constant and low loss, and is very suitable for high-frequency / broadband applications. The thickness of the dielectric substrate 6 is about 0.01 - 0.1 times the vacuum wavelength. The thickness of the dielectric substrate 6 is 0.01 times the vacuum wavelength, 0.05 times the vacuum wavelength or 0.1 times the vacuum wavelength. The small thickness of the dielectric substrate 6 is beneficial to reducing the occupied area of the entire antenna.

[0046] Specifically, the radiation side lengths of the driving patch 1 and the coupling patch are 1 / 4 of the dielectric wavelength at the resonant frequency, while the side length of the traditional square patch antenna is 1 / 2 of the dielectric wavelength at the resonant frequency. Therefore, compared with the traditional square patch antenna, the size of the antenna in this solution is reduced by half.

[0047] Please refer to Figures 6 to 8 , Figure 6 which are the cross-sectional radiation patterns at φ = 0° and φ = 90° of the compact-sized broadband circularly polarized patch antenna according to an embodiment of the present invention at the frequency point of 1.52 GHz; Figure 7 which are the cross-sectional radiation patterns at φ = 0° and φ = 90° of the compact-sized broadband circularly polarized patch antenna according to an embodiment of the present invention at the frequency point of 1.54 GHz; Figure 8 which are the cross-sectional radiation patterns at φ = 0° and φ = 90° of the compact-sized broadband circularly polarized patch antenna according to an embodiment of the present invention at the frequency point of 1.57 GHz. Figures 6 to 8The cross-sectional radiation patterns of the antenna at φ = 0° and φ = 90° under three frequency points. It can be seen from the figure that the radiation patterns of the antenna can remain stable under the three frequency points.

[0048] In summary, this solution proposes a compact structure-size broadband circularly polarized antenna based on short-circuited triangular patch coupling. The antenna designed in this way adopts a single-feed form, and short-circuited metallized vias 4 are loaded on the triangular patch to reduce the size of the antenna. Circular polarization is generated by the coupling between the patches, without the need for an additional power divider and phase shifter network, further reducing the overall size of the antenna. Two axial ratio zeros are generated by the coupling of three radiators, greatly broadening the axial ratio bandwidth of the antenna.

[0049] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the concept of the technical solution of the present invention by using the content of the specification and drawings of the present invention, or any direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A broadband circularly polarized patch antenna with a compact size, characterized in that, Comprising: A dielectric substrate having opposite first and second surfaces; A driving patch, a first coupling patch, and a second coupling patch. The driving patch, the first coupling patch, and the second coupling patch are all right-angled triangles. The three are adjacent and spaced apart on the first surface of the dielectric substrate. The driving patch and the first coupling patch are electromagnetically coupled to form a circular polarization axial ratio zero point, and the first coupling patch and the second coupling patch are electromagnetically coupled to form another circular polarization axial ratio zero point. A row of metallized vias is provided on one side of the dielectric substrate corresponding to the driving patch, the first coupling patch, and the second coupling patch. The three rows of metallized vias are electrically connected to the driving patch, the first coupling patch, and the second coupling patch respectively. Among them, the driving patch and the first coupling patch are symmetrically arranged, and the two rows of metallized vias are orthogonally arranged; the first coupling patch and the second coupling antenna are symmetrically arranged, and the two rows of metallized vias are orthogonally arranged; the driving patch and the second coupling patch are centrosymmetrically arranged, and the two rows of metallized vias are arranged side by side; the distance between the driving patch and the first coupling patch is less than the distance between the first coupling patch and the second coupling patch; the distance between adjacent metallized vias is equidistant. The distance between adjacent metallized vias in the driving patch is greater than the distance between adjacent metallized vias in the second coupling patch, and the distance between adjacent metallized vias in the second coupling patch is greater than the distance between adjacent metallized vias in the first coupling patch; A ground plane provided on the second surface of the dielectric substrate.

2. The compact-sized broadband circularly polarized patch antenna according to claim 1, characterized in that It further includes a feeding structure composed of a metal probe and the outer conductor of an SMA connector. The metal probe is provided on the dielectric substrate, and one end of the metal probe is electrically connected to the driving patch, and the other end is arranged to avoid the ground plane; the outer conductor of the SMA connector is electrically connected to the ground plane.

3. The compact-size broadband circularly polarized patch antenna according to claim 1, characterized in that, The thickness of the dielectric substrate is 0.01 - 0.1 times the vacuum wavelength.

4. The compact-sized broadband circularly polarized patch antenna according to claim 1, characterized in that, The radiation side lengths of the driving patch and the coupling patch are 1 / 4 of the dielectric wavelength at the resonant frequency.

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