A double-layer differentially fed circularly polarized antenna

Abstract

The present invention discloses a double-layer differential feed circularly polarized antenna, which belongs to the field of wireless communication technology, and includes a metal cover plate, a dielectric substrate, a strip differential feed line pair, a parasitic structure, and a circularly polarized radiator. The metal cover plate is arranged on the dielectric substrate, and the circularly polarized radiator is arranged through the metal cover plate. The strip differential feed line pair and the parasitic structure are both arranged on the dielectric substrate, and are located between the metal cover plate and the dielectric substrate. The present invention adopts a double-layer plate structure, which will not cause lamination deviation problems, and can also greatly reduce production costs; and directly utilizes the two radiation arms and parasitic structures of the differential feed pair, and radiates the signal with the help of a circularly polarized radiator of a special shape, which simplifies the signal transmission process and greatly reduces the complexity of the antenna; the position of the differential feed line pair facilitates the automatic surface mounting of the chip, which can meet the chip integration requirements and is conducive to the integration and large-scale production of system boards.

Description

Technical Field

[0001] The invention relates to the technical field of wireless communications, and in particular to a double-layer differentially fed circularly polarized antenna. Background Art

[0002] With the development of science and technology, the millimeter wave frequency band has received more and more attention. Due to its advantages such as wide absolute bandwidth, short wavelength, and special atmospheric propagation characteristics, it has great potential for application in future communication, radar and other systems. At the same time, differential signal operation is more suitable for high-level integration of the system, improving the system's anti-interference ability and reducing the system's high-order harmonic interference, improving the system's dynamic range, and using differential signal systems. If the antenna adopts differential feeding, it can be directly connected to the back-end system, thereby getting rid of the use of large lossy baluns and improving the receiving noise performance and transmission power efficiency. On the other hand, compared with linear polarization, circularly polarized antennas can provide more potential channel capabilities. Circularly polarized signals are conducive to suppressing multipath interference and suppressing the influence of weather such as rain and fog.

[0003] At present, most circular polarization feeding methods are non-differential feeding, and the more common ones are waveguide feeding, coaxial feeding, single-ended feeding, etc., which are not easy to integrate into the system. In addition, due to the relatively small physical size of millimeter wave antennas, difficulties in design and processing have seriously limited the implementation of circular polarization antennas. There are also a few circular polarization feeding methods that use differential feeding, but their structures are relatively complex, difficult to process, and it is difficult to ensure the design performance of the antenna. Therefore, a double-layer differentially fed circularly polarized antenna is proposed. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to solve the problems of complex structure, difficult processing and difficulty in ensuring antenna design performance of existing circularly polarized antennas under differential feeding mode, and provide a double-layer differential feeding circularly polarized antenna.

[0005] The present invention solves the above technical problems through the following technical solutions. The present invention includes a metal cover plate, a dielectric substrate, a strip differential feed line pair, a parasitic structure, and a circularly polarized radiator. The metal cover plate is arranged on the dielectric substrate, the circularly polarized radiator is arranged through the metal cover plate, and the strip differential feed line pair and the parasitic structure are both arranged on the dielectric substrate and located between the metal cover plate and the dielectric substrate.

[0006] Furthermore, an upper metal film is disposed on the upper surface of the dielectric substrate, and a lower metal film is disposed on the lower surface, and the strip differential feed line pair and the parasitic structure are coplanar with the upper metal film.

[0007] Furthermore, the circularly polarized radiator is a tubular structure, including an alternating section, the bottom aperture shape of the alternating section is a circle, the aperture shape upward from the bottom is the intersection of a circle and a rectangle whose geometric centers coincide, and the circular size of the upper aperture shape of the alternating section gradually increases based on the circular size of the bottom aperture shape.

[0008] Furthermore, the center of the circle of the upper aperture shape and the center of the circle of the bottom aperture shape are on the same straight line.

[0009] Furthermore, the circularly polarized radiator also includes a transition section, the top of the transition section is connected to the bottom of the alternating section, and the bottom of the transition section and the bottom of the alternating section have the same diameter and shape as a circle.

[0010] Furthermore, a circular opening matching the bottom diameter and position of the alternating segment is formed on the upper metal film, and the center of the circular opening is in a straight line with the center of the bottom diameter of the alternating segment.

[0011] Furthermore, the circular opening is provided with a reserved opening for arranging the strip differential feeder line pair.

[0012] Furthermore, the strip differential feed line pair includes two metal strip lines arranged in parallel on the upper surface of the dielectric substrate, a radiation arm is arranged at the end of the metal strip line, the metal strip line and the radiation arm are integrally formed, the angle between the radiation arms of the two metal strip lines is 180°, and the radiation arm has a certain angle with the long side of the metal cover plate.

[0013] Furthermore, a plurality of stepped impedance lines for ensuring that the electrical lengths of the two metal strip lines are the same are arranged on the shorter metal strip line in the strip differential feed line, and the metal strip line and the stepped impedance line are integrally formed.

[0014] Furthermore, the width of the parasitic structure is not kept consistent, and the long side of the parasitic structure is arranged in parallel with the radiation arm at an interval.

[0015] Compared with the prior art, the present invention has the following advantages: the double-layer differentially fed circularly polarized antenna adopts a double-layer board structure, which will not cause lamination deviation problems and can also greatly reduce production costs; and directly utilizes the two radiation arms and parasitic structures of the differential feed pair, and radiates the signal with the help of a circularly polarized radiator of a special shape, which simplifies the signal transmission process and greatly reduces the complexity of the antenna; the position of the differential feed line pair facilitates the automatic surface mounting of the chip, can meet the chip integration requirements, is conducive to the integration and large-scale production of system boards, and is worthy of being promoted and used. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1is a schematic structural diagram of a circularly polarized antenna in Embodiment 1 of the present invention;

[0017] Figure 2 is a schematic diagram of a top view of the structure of a strip differential feeder pair in the first embodiment of the present invention;

[0018] Figure 3 is a schematic diagram of a receiving and transmitting linear array in the same plane in the second embodiment of the present invention;

[0019] Figure 4 It is a schematic diagram of a transmitting and receiving array in the same plane in the third embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0021] Embodiment 1

[0022] like Figure 1 As shown, this embodiment provides a technical solution: a double-layer differentially fed circularly polarized antenna applied to the millimeter wave frequency band, mainly including a metal cover plate 101, a dielectric substrate 105, a strip differential feed line pair 106, and a parasitic structure 103.

[0023] A circularly polarized radiator 102 is disposed inside the metal cover plate 101 . The circularly polarized radiator 102 is a hollow metal tubular structure with a diameter gradually increasing from bottom to top.

[0024] The metal cover plate 101 is cut along the length direction of the strip differential feed line pair 106 to meet the chip integration requirements; the dielectric substrate 105 has the same width as the metal cover plate 101; an upper metal film is printed on the lower surface of the dielectric substrate 105, and a lower metal film is printed on the upper surface of the dielectric substrate 105; a circular opening 104, a strip differential feed line pair 106 and a parasitic structure 103 are arranged on the upper metal film, and a number of metallized vias 107 are arranged around the circular opening 104.

[0025] The strip differential feed line pair 106 includes two metal strip lines arranged parallel to each other; the ends of the strip differential feed line pair 106 are bent and opened 180 degrees to form a radiating arm similar to a dipole antenna, which is used to achieve coupled feeding of the parasitic structure 103; the long side of the radiating arm is parallel to the parasitic structure 103; the strip differential feed line pair 106 forms an angle of a certain size with the long side of the metal cover plate 101, and a number of metalized vias 107 are arranged on both sides of the strip differential feed line.

[0026] The width of the strip differential feed line pair 106 and the distance between the two metal strip lines are designed and adjusted according to the transmission line theory.

[0027] The dielectric substrate 105 has a thickness of h1 and a relative dielectric constant of ε r .

[0028] The size of the radiating arm is about 0.8λ, where λ is the wavelength corresponding to the center frequency.

[0029] The long side dimension of the parasitic structure is about 0.4λ, where λ is the wavelength corresponding to the center frequency.

[0030] The height of the metal cover plate 101 is h2.

[0031] like Figure 2 As shown, a plurality of stepped impedance lines are arranged on one metal strip line of the strip differential feed line pair 106 of this embodiment to ensure that the electrical lengths of the two metal strip lines are the same.

[0032] The working principle of this embodiment is: when the antenna is working, the signal is fed from one end of the strip differential feed line pair 106, and coupled to the parasitic structure 103 through the radiating arm at the end thereof, causing the radiating arm and the parasitic structure 103 to resonate and radiate together. The radiated linear polarization signal can be decomposed into a polarization component parallel to the short side of the metal cover plate 101 and a polarization component parallel to the long side of the metal cover plate 101 when passing through the circularly polarized radiator 102. Since the sizes of the long side and the short side of the circularly polarized radiator 102 are different, the propagation constants of the two polarization components are different. Therefore, when the two polarization components propagate along the circularly polarized radiator 102 to the radiation aperture, the phase difference is close to 90°. According to the formation mechanism of circularly polarized electromagnetic waves, the two polarization components are superimposed to finally form a circularly polarized electromagnetic wave that radiates into space.

[0033] Embodiment 2

[0034] like Figure 3 As shown, Figure 3 This is a double-layer differentially fed circularly polarized antenna linear array of this embodiment, and the array size is 8×8. The antenna units in the linear array adopt the double-layer differentially fed circularly polarized antenna in the first embodiment.

[0035] Embodiment 3

[0036] like Figure 4 As shown, Figure 4 This is a double-layer differentially fed circularly polarized antenna array of this embodiment, with an array size of 8×8. The antenna units in the array adopt the double-layer differentially fed circularly polarized antenna in the first embodiment.

[0037] In summary, the double-layer differentially fed circularly polarized antenna applied to the millimeter wave frequency band of this embodiment adopts a double-layer board structure, which will not cause lamination deviation problems and can also greatly reduce production costs; and directly utilizes the two radiation arms and parasitic structures of the differential feed pair, and radiates the signal with the help of a specially shaped circularly polarized radiator, which simplifies the signal transmission process and greatly reduces the complexity of the antenna; the position of the differential feed line pair facilitates the automatic surface mounting of the chip, which can meet the chip integration requirements and is conducive to the integration and large-scale production of system boards.

[0038] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A double-layer differentially fed circularly polarized antenna, characterized in that: It comprises a metal cover plate, a dielectric substrate, a strip differential feed line pair, a parasitic structure, and a circularly polarized radiator, wherein the metal cover plate is arranged on the dielectric substrate, the circularly polarized radiator is arranged through the metal cover plate, and the strip differential feed line pair and the parasitic structure are both arranged on the dielectric substrate and located between the metal cover plate and the dielectric substrate; An upper metal film is disposed on the upper surface of the dielectric substrate, and a lower metal film is disposed on the lower surface, and the strip differential feed line pair and the parasitic structure are coplanar with the upper metal film; The circularly polarized radiator is a tubular structure, comprising an alternating section, wherein the bottom aperture shape of the alternating section is a circle, and the aperture shape upward from the bottom is the intersection of a circle and a rectangle whose geometric centers coincide, and the circular size of the upper aperture shape of the alternating section gradually increases based on the circular size of the bottom aperture shape; The center of the circle of the upper aperture shape is in the same straight line as the center of the circle of the bottom aperture shape; The circularly polarized radiator further comprises a transition section, the top of the transition section is connected to the bottom of the alternating section, and the bottom of the transition section and the bottom of the alternating section are both circular with the same size; The circular opening is provided with a reserved opening for arranging the strip differential feeder pair. The strip differential feeder pair comprises two metal strips arranged in parallel on the upper surface of the dielectric substrate. A radiation arm is arranged at the end of the metal strip. The metal strip and the radiation arm are integrally formed. The angle between the radiation arms of the two metal strips is 180°. The radiation arm has a certain angle with the long side of the metal cover plate. The width of the parasitic structure is not consistent, and the long side of the parasitic structure is arranged in parallel with the radiation arm at an interval; The size of the radiating arm is approximately 0.8 The long side dimension of the parasitic structure is about 0.4 ,in is the center frequency corresponding to the wavelength.

2. A double-layer differentially fed circularly polarized antenna according to claim 1, characterized in that: A plurality of stepped impedance lines are arranged on the shorter metal strip line in the strip differential feed line to ensure that the electrical lengths of the two metal strip lines are the same, and the metal strip line and the stepped impedance line are integrally formed.

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