A broadband dual circularly polarized full-duplex patch antenna

Abstract

The present invention provides a broadband dual-circularly polarized full-duplex patch antenna, comprising a two-port feed network, a 0.762mm thick dielectric plate, a metal floor, an air layer, a 0.508mm thick dielectric plate, a right-handed circularly polarized radiating unit, a left-handed circularly polarized radiating unit, and a grounded metal post. The metal floor is disposed on the upper surface of the 0.762mm thick dielectric plate, and is provided with four rectangular feed slots of equal size, a four-pointed star slot, and three rectangular slots. The air layer is disposed between the metal floor and the 0.508mm thick dielectric plate. The left-handed and right-handed circularly polarized wave radiating patches are stepped radiating patches, symmetrically disposed on the upper surface of the 0.508mm thick dielectric plate. The present invention uses a stepped antenna as an antenna unit and introduces a new circular polarization mode, which greatly improves the axial ratio bandwidth of the antenna. Simultaneously, a decoupling structure consisting of a defective ground and a grounded metal post is used to effectively reduce coupling between the transmitting and receiving antennas. With little change in impedance matching and axial ratio, the antenna 3dB gain bandwidth is widened, while isolation is significantly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of antennas, and in particular relates to a broadband dual-circular polarization full-duplex patch antenna. Background Art

[0002] With the rapid development of wireless communication technology, wireless spectrum resources are becoming increasingly depleted. Simultaneous, full-duplex technology can more effectively utilize limited spectrum resources. Circularly polarized antennas, with their advantages of multipath interference immunity and excellent polarization matching, hold broad application prospects in satellite communication systems, radar systems, and radio frequency identification. Circularly polarized patch antennas have attracted widespread research interest due to their low profile, ease of fabrication, and low cost.

[0003] The operating bandwidth of circularly polarized full-duplex antennas must simultaneously meet requirements such as impedance matching, axial ratio, and gain. Therefore, generally speaking, circularly polarized full-duplex antennas, while achieving a certain degree of isolation, have a relatively narrow operating bandwidth, making them difficult to meet the requirements of broadband wireless communication systems. Wide-bandwidth full-duplex antennas are generally linearly polarized antennas, which are susceptible to multipath interference and cannot meet the operating requirements of some scenarios. Circularly polarized full-duplex patch antennas may also have the problem of low gain. Circularly polarized full-duplex patch antennas that combine broadband, high isolation, and high gain are relatively rare. The following introduces some of the published patents:

[0004] Chinese patent application CN115799827A discloses a circularly polarized compact full-duplex antenna and wireless communication device. This antenna achieves filtering and high isolation by placing shorting pins in a ring around the center of the transmitting antenna's radiating patch and at the edge of the receiving antenna's radiating patch. However, the transmitting and receiving antennas cannot operate at the same frequency, and circular polarization is only available in the high-frequency band.

[0005] Chinese patent application CN113078482A discloses a C-band dual-port circularly polarized, high-isolation antenna array. This antenna connects 16 radiating elements via a full-duplex feed network, achieving dual circular polarization for both the transmit and receive antennas. While the dual-port antennas offer high port isolation, the antenna utilizes a complex feed network, resulting in a narrow impedance bandwidth and a narrow 3dB axial ratio bandwidth.

[0006] Chinese patent application CN113328255A discloses a low-profile, dual-port, high-isolation, dual-circularly polarized antenna array. This antenna utilizes a full-duplex feed network consisting of a 180° hybrid network and a 180° balun, achieving co-directional circular polarization and high isolation at both ports. However, the antenna's dual-port common 3dB axial ratio relative bandwidth is only 0.69% (5.77GHz-5.81GHz), and its 10dB impedance relative bandwidth is only 3.8% (5.66GHz-5.88GHz). Summary of the Invention

[0007] In response to the problems in the background technology, the present invention develops a broadband dual circularly polarized full-duplex patch antenna. The purpose is to use a simple antenna unit, feeding structure and decoupling structure to simultaneously achieve the working requirements of broadband, high gain and dual-port high isolation, so as to meet the simultaneous and co-frequency operation of dual circular polarization.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A broadband dual circularly polarized full-duplex patch antenna comprises a two-port feeding network, a 0.762mm thick dielectric plate, a metal floor, an air layer, a 0.508mm thick dielectric plate, a right-handed circularly polarized radiating unit, a left-handed circularly polarized radiating unit, and a grounded metal column; the two-port feeding network is arranged on both sides of the lower surface of the 0.762mm thick dielectric plate, and the feeding network is respectively connected to an excitation port; the metal floor is arranged on the upper surface of the 0.762mm thick dielectric plate, and the metal floor is provided with four rectangular feeding slots of the same size, a four-pointed star slot, and Three rectangular slots, wherein the rectangular feeding slot is located around the metal floor, the four-pointed star slot is located in the middle of the metal floor, and the rectangular slots are located on the metal floor in sequence along the symmetry axis of the antenna; the air layer is arranged between the metal floor and the 0.508mm thick dielectric plate; the right-handed circularly polarized wave radiation patch and the left-handed circularly polarized wave radiation patch are stepped radiation patches, symmetrically arranged on the upper surface of the 0.508mm thick dielectric plate, and the grounding metal column passes through the 0.762mm dielectric plate, the air layer and the 0.508mm dielectric plate.

[0010] Furthermore, of the four rectangular feeding slots of the same size, two are horizontally arranged on both sides of one end of the metal floor, and the other two are vertically arranged on both sides of the other end of the metal floor.

[0011] Furthermore, two of the rectangular grooves are located on both sides of the symmetry axis, and the other rectangular groove passes through the four-pointed star-shaped groove.

[0012] Furthermore, there are 16 grounding metal pillars, which penetrate the 0.762mm dielectric plate, the air layer and the 0.508mm dielectric plate and are arranged near the four-pointed star groove and the rectangular groove.

[0013] Furthermore, the right-handed circularly polarized radiation unit and the left-handed circularly polarized radiation unit are both composed of two stepped radiation patches rotated by 38°.

[0014] Furthermore, there are two groups of right-handed circularly polarized radiation units, which are respectively located on the upper and lower sides of the right side of the 0.508mm thick dielectric plate, and one group is obtained by rotating the other group 90° around the center of the antenna; there are two groups of left-handed circularly polarized radiation units, which are respectively located on the upper and lower sides of the left side of the 0.508mm thick dielectric plate, and one group is obtained by rotating the other group 90° around the center of the antenna; and the right-handed circularly polarized radiation units and the left-handed circularly polarized radiation units are symmetrically distributed. When the right-handed (left-handed) circularly polarized antenna part is used as a transmitting antenna, the left-handed (right-handed) circularly polarized antenna part is used as a receiving antenna.

[0015] Furthermore, the feeding network is connected to the rectangular feeding slot through microstrip lines.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] Since most of the currently disclosed broadband full-duplex antennas are linearly polarized antennas, the present invention uses a stepped antenna with broadband circular polarization performance as the antenna unit, and utilizes two improved T-shaped power splitters to connect the two antenna units of the transmitting and receiving antennas respectively to realize sequential rotation feeding, thereby achieving broadband operation while meeting circular polarization.

[0018] To address the problems reported in existing circularly polarized full-duplex antennas, such as low port isolation or high isolation only within a narrow band, the present invention utilizes a decoupling structure consisting of a defective ground (composed of a four-pointed star slot and a rectangular slot) and a grounded metal post. This structure effectively reduces coupling between the transmitting and receiving antennas, broadens the antenna's 3dB gain bandwidth while maintaining minimal impedance matching and axial ratio changes, and significantly improves isolation, achieving an isolation greater than 25dB within the operating bandwidth.

[0019] The transmitting and receiving antenna units of the present invention are symmetrical antenna units of the same type, and the transmitting and receiving antennas have high similarity in performance, so that the -10dB impedance matching bandwidth, 3dB axial ratio bandwidth, and 3dB gain bandwidth of the transmitting and receiving antennas are highly overlapped, realizing the same-frequency broadband operation of the circularly polarized full-duplex antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0021] Figure 2 It is a side view of the present invention.

[0022] Figure 3 It is a top view of the present invention.

[0023] Figure 4is the S parameter of the antenna of the present invention.

[0024] Figure 5 This is the axial ratio curve of the antenna of the present invention.

[0025] Figure 6 This is a gain comparison diagram of the present invention with and without a decoupling structure.

[0026] Figure 7 This is the radiation pattern of the XOZ plane at 8.2 GHz when the port 101 of the present invention is excited.

[0027] Figure 8 This is the radiation pattern of the YOZ plane at 8.2 GHz when the port 101 of the present invention is excited.

[0028] Figure 9 This is the radiation pattern of the XOZ plane at 15 GHz when the port 101 of the present invention is excited.

[0029] Figure 10 This is the radiation pattern of the YOZ plane at 15 GHz when the port 101 of the present invention is excited. DETAILED DESCRIPTION

[0030] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0031] like Figures 1 to 3 As shown, the broadband dual circularly polarized full-duplex array antenna proposed in the present invention includes a two-port feeding network 100, an excitation port 101, an excitation port 102, a 0.762 mm thick dielectric plate 200, a metal floor 300, an air layer 400, a 0.508 mm thick dielectric plate 500, a right-handed circularly polarized radiation unit 601, and a left-handed circularly polarized radiation unit 602.

[0032] A two-port feed network 100 is printed on the bottom surface of the dielectric plate 200. The excitation port 101 is connected to the two-port feed network 100. A metal floor 300 is printed on the top surface of the dielectric plate 200. Four rectangular feed slots 301 of equal size are etched on the metal floor 300. A four-pointed star-shaped slot 302 is etched in the center of the metal floor 300. Three rectangular slots 303 are etched sequentially along the antenna's axis of symmetry. An air layer 400 is located between the metal floor 300 and the 0.508 mm thick dielectric plate 500. Sixteen grounded metal posts 701 penetrate the 0.762 mm thick dielectric plate 200, the air layer 400, and the 0.508 mm thick dielectric plate 500 and are arranged near the four-pointed star-shaped slot 302 and the rectangular slot 303. Right-handed circularly polarized radiating elements 601 and left-handed circularly polarized radiating elements 602 are printed on the top surface of the dielectric plate 500.

[0033] The antenna radiates right-hand (left-hand) circularly polarized waves, wherein the right-hand (left-hand) circularly polarized radiating unit 601 (602) is composed of a stepped radiating patch 601a (602a) and a radiating patch 601b (602b) rotated by a certain angle (38°). The right-hand circularly polarized antenna portion and the left-hand circularly polarized antenna portion are symmetrically distributed. When the right-hand (left-hand) circularly polarized antenna portion serves as a transmitting antenna, the left-hand (right-hand) circularly polarized antenna portion serves as a receiving antenna.

[0034] like Figure 3 As shown, when transmitting right-handed (left-handed) circularly polarized waves, the antenna is fed through the excitation port 101 (102), and the energy is transmitted to the two-port feeding network 100. After passing through the feeding network 100, the same power and energy with a phase difference of 90° are transmitted to the two ports. The two ports are then connected to the microstrip line 103, and the energy is coupled to the right-handed (left-handed) circularly polarized radiation unit 601 (602) on the 0.508mm thick dielectric plate through the rectangular feeding slot 301.

[0035] like Figure 4 As shown, the frequency range in which the common impedance matching between the antenna's two ports is below -10dB is 7.02-17.52GHz, with a relative impedance matching bandwidth of 85.6%. Furthermore, isolation is consistently above 25dB within the operating frequency band. The decoupling structure, consisting of a four-pointed star slot, a rectangular slot, and metal pillars, significantly improves dual-port isolation.

[0036] like Figure 5 As shown in the figure, the frequency band in which the common axial ratio of the transmitting and receiving antennas is lower than 3dB is 7.94-16.87GHz, and the axial ratio relative bandwidth reaches 72%.

[0037] like Figure 6As shown in the figure, the antennas for comparison are a dual circular polarization full duplex antenna without a decoupling structure and a dual circular polarization full duplex patch antenna with a decoupling structure. Figure 6 Before the decoupling structure, the gain of the antenna drops significantly in the 12.24GHz-13.73GHz frequency band, affecting the 3dB gain bandwidth. After the decoupling structure is introduced, the 3dB gain frequency band of the dual circularly polarized full-duplex patch antenna is 6.22-16.24GHz, and the 3dB gain relative bandwidth reaches 89.2%.

[0038] like Figure 7 and Figure 8 As shown, it is the radiation pattern of the dual circular polarization full duplex patch antenna port 101 at 8.2GHz in the XOZ plane and the YOZ plane. Figure 9 and Figure 10 As shown, the radiation pattern of the dual circularly polarized full-duplex patch antenna port 101 at 15 GHz in the XOZ plane and the YOZ plane when it is excited.

[0039] This invention uses a stepped radiating patch antenna as the antenna element. Compared to the original rectangular radiating patch, this stepped antenna element introduces a new circular polarization mode, significantly improving the antenna's axial ratio bandwidth and laying the foundation for broadband operation of the entire full-duplex antenna. Furthermore, the antenna element's original right-handed circularly polarized waves can be transformed into left-handed circularly polarized waves through symmetrical manipulation, facilitating the implementation of dual circular polarization in this invention.

[0040] The array antenna of the present invention uses a decoupling structure consisting of a defective ground and metal pillars to reduce the isolation between the two ports, allowing the antenna isolation to be maintained above 25dB within the operating frequency band. At the same time, without affecting the impedance bandwidth and axial ratio bandwidth, the antenna gain is made flat, achieving the effect of widening the gain bandwidth by 3dB.

[0041] The broadband dual-circularly polarized full-duplex array antenna of the present invention has a common impedance matching of less than -10dB at both ports over a frequency range of 7.02-17.52GHz, achieving an impedance matching relative bandwidth of 85.6%. The common axial ratio of the transmitting and receiving antennas is less than 3dB over a frequency range of 7.94-16.87GHz, achieving an axial ratio relative bandwidth of 72%. The common 3dB gain of the transmitting and receiving antennas is also achieved over a frequency range of 6.22-16.24GHz, achieving a 3dB gain relative bandwidth of 89.2%, and reaching a maximum gain of 9.44dBic at 10GHz. In summary, the antenna of the present invention operates over a frequency range of 7.94-16.24GHz, achieving a relative bandwidth of 68.7%.

[0042] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. 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 broadband dual circularly polarized full-duplex patch antenna, characterized by: The antenna comprises a two-port feeding network, a 0.762mm thick dielectric plate, a metal floor, an air layer, a 0.508mm thick dielectric plate, a right-handed circularly polarized radiating unit, a left-handed circularly polarized radiating unit, and a grounded metal column; the two-port feeding network is arranged on both sides of the lower surface of the 0.762mm thick dielectric plate, and the feeding networks are respectively connected to the excitation ports; the metal floor is arranged on the upper surface of the 0.762mm thick dielectric plate, and the metal floor is provided with four rectangular feeding slots of the same size, a four-pointed star slot, and three rectangular slots, wherein the rectangular feeding slots are located around the metal floor, the four-pointed star slot is located in the middle of the metal floor, and the rectangular slots are sequentially located on the metal floor along the symmetry axis of the antenna; the air layer is arranged between the metal floor and the 0.508mm thick dielectric plate; The right-handed circularly polarized radiation unit and the left-handed circularly polarized radiation unit are both composed of two stepped radiation patches rotated 38°. The right-handed circularly polarized radiation unit is divided into two groups, which are respectively located on the upper and lower sides of the right side of the 0.508mm thick dielectric plate, and one group is obtained by rotating the other group 90° around the center of the antenna; the left-handed circularly polarized radiation unit is divided into two groups, which are respectively located on the upper and lower sides of the left side of the 0.508mm thick dielectric plate, and one group is obtained by rotating the other group 90° around the center of the antenna, and the right-handed circularly polarized radiation unit and the left-handed circularly polarized radiation unit are symmetrically distributed; the grounding metal column passes through the 0.762mm dielectric plate, the air layer and the 0.508mm dielectric plate.

2. The broadband dual circularly polarized full-duplex patch antenna according to claim 1, wherein: Two of the four rectangular feeding slots of the same size are horizontally arranged on both sides of one end of the metal floor, and the other two are vertically arranged on both sides of the other end of the metal floor.

3. The broadband dual circularly polarized full-duplex patch antenna according to claim 1, wherein: Two of the rectangular grooves are located on both sides of the symmetry axis, and the other rectangular groove passes through the four-pointed star-shaped groove.

4. A broadband dual circularly polarized full-duplex patch antenna according to claim 1 or 3, characterized in that: There are 16 grounding metal pillars, which penetrate the 0.762mm dielectric plate, the air layer and the 0.508mm dielectric plate and are arranged near the four-pointed star groove and the rectangular groove.

5. The broadband dual circularly polarized full-duplex patch antenna according to claim 1, wherein: The feeding networks are connected to the rectangular feeding slots through microstrip lines.

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