Microwave and millimeter wave dual-band circularly polarized common structure antenna

Abstract

The invention discloses a microwave and millimeter wave circularly-polarized dual-band common-structure antenna which is made of full metal and realizes efficient combination of a microwave antenna structure and a millimeter wave antenna structure through a structure multiplexing method. The millimeter wave antenna structure is a 2 * 2 end-fire array antenna, and the one-to-four power divider provides equal-amplitude and equal-phase excitation for an array unit. A radiation structure of the microwave antenna is located at the center of the millimeter wave array, and a feed structure is accessed from a metal hole reserved by penetrating through the antenna floor from the lower part. According to the invention, while compact integration of two frequency band antennas with large frequency ratio is realized, the antenna has the advantages of wide working frequency band, stable circular polarization radiation performance, easy structure processing, high radiation efficiency and the like, and can show competitiveness in a future B5G / 6G communication system.

Description

Technical Field

[0001] This invention discloses a microwave and millimeter-wave dual-band circularly polarized co-structure antenna, which achieves compact integration of two frequency bands using a structure multiplexing method. Background Technology

[0002] The rapid development of mobile communication technology has led to increasing congestion of microwave frequency bands. To address this issue, modern communication systems are gradually expanding their carrier frequencies to the millimeter-wave band. As a core component of wireless communication systems, antennas are essential for meeting the application requirements of communication systems sharing both microwave and millimeter-wave frequency bands. Therefore, research and design of high-ratio integrated antennas are necessary. Compared to linearly polarized antennas, circularly polarized antennas can effectively reduce polarization mismatch loss, allowing for more flexible directional angles between the transmitter and receiver, superior mobility, and effective suppression of the effects of channel multipath distortion and rain attenuation. They are widely used in radar and satellite communication systems. Therefore, research on high-ratio dual-band circularly polarized antennas has significant engineering application value and theoretical research significance.

[0003] Dual-frequency integration technology has proposed several implementation schemes, which can be mainly divided into the following three categories:

[0004] 1. Multimode technology achieves dual-band integrated design by exciting different operating modes in a single radiator. Existing dual-band antennas based on this technology mostly have a frequency ratio of less than 3, and the frequency distance between the two operating frequency bands is relatively close, making it difficult to apply to the design of dual-band integrated antennas with large frequency ratios in microwave and millimeter waves.

[0005] 2. Overlapping topology: This method improves aperture efficiency by vertically embedding an antenna structure of one frequency band into an antenna structure of another frequency band, but it degrades the isolation performance between antennas and limits the range of its operating frequency bands.

[0006] 3. Structure reuse technology: By reusing the radiator structure of different frequency bands, dual-band antenna integration can be achieved. It can realize the high frequency ratio design of dual-band antennas in a compact structural size, effectively reducing antenna volume and design cost. It is suitable for integrated design of microwave and millimeter wave bands. Summary of the Invention

[0007] The purpose of this invention is to provide a microwave and millimeter-wave circularly polarized dual-band co-structure antenna. Through structural multiplexing, the antenna can simultaneously achieve broadband, high-efficiency circularly polarized radiation in both the Sub-6 GHz band and the millimeter-wave band, while also possessing the advantage of a compact structure.

[0008] To achieve the above objectives, the solution of the present invention is:

[0009] A microwave / millimeter-wave circularly polarized dual-band co-structure antenna includes:

[0010] Metal flooring;

[0011] Millimeter-wave radiating structures are symmetrically distributed at the center of the metal floor.

[0012] A microwave radiation structure is located at the center of the millimeter-wave radiation structure;

[0013] A millimeter-wave feeding structure, located below the metal floor, employs a waveguide power divider to provide equal-amplitude and equal-phase excitation to the millimeter-wave radiating array elements;

[0014] A microwave feeding structure is inserted from below the metal floor, and the feeding path is the gap between the millimeter-wave radiation array elements, which feeds the microwave radiation structure.

[0015] Furthermore, the millimeter-wave radiation array element is a stepped septum waveguide, which divides the rectangular waveguide into two cavities of the same size, and the arrangement of the septums is axially symmetrical, in order to achieve circularly polarized radiation in the millimeter-wave band.

[0016] Furthermore, each partition waveguide has an outwardly extending metal plate at its top, and two diagonally opposite metal plates are connected by a metal strip, which is used to reuse the outer wall of the waveguide and the metal plate as a circularly polarized radiation structure for the microwave frequency band.

[0017] Furthermore, the millimeter-wave feeding structure adopts an air-filled rectangular waveguide structure, and achieves four-channel equal-amplitude and in-phase output by cascading multiple 1-to-2 power dividers in the vertical direction.

[0018] Furthermore, the waveguide power divider includes:

[0019] A first-stage 1-to-2 power divider, the input port of which serves as the input port of the millimeter-wave feed structure;

[0020] Two second-stage 1-to-2 power dividers have their input terminals connected to the two output ports of the first-stage 1-to-2 power divider, respectively, and the output ports are connected to the millimeter-wave radiation array element.

[0021] Furthermore, the microwave feeding structure includes a bent metal probe and a coaxial cable; the bent metal probe is disposed within the gap of the millimeter-wave radiation array element, and the probe direction is perpendicular to the direction of the metal partition; the coaxial cable is inserted from a channel reserved in the metal floor, and its inner conductor is connected to the bent metal probe.

[0022] Furthermore, metal fences are installed at the four corners of the metal floor to improve the circular polarization performance of the antenna.

[0023] After adopting the above scheme, the microwave and millimeter-wave radiation structure and feeding structure proposed in this invention are combined to form a microwave and millimeter-wave dual-band circularly polarized co-structure antenna. The microwave radiation structure uses a magnetoelectric dipole composed of a top metal plate and the outer wall of the waveguide, while the feeding structure uses a bent metal probe and a coaxial line. The millimeter-wave radiation structure uses a septum waveguide as the radiating element, and the feeding structure uses a waveguide power divider formed by an air-filled waveguide. The antenna structure of this invention has the advantages of large impedance bandwidth, large axial ratio bandwidth, good isolation, compact structure, and high radiation efficiency in the microwave and millimeter-wave bands, making it a powerful solution for future communication systems.

[0024] Beneficial effects:

[0025] 1. This invention achieves a highly reusable and compact antenna structure by extending a metal plate outward from the top of a millimeter-wave radiating structure and simultaneously reusing horizontal and vertical metal structures to construct a magnetoelectric dipole for the microwave radiating structure. Furthermore, by connecting the top diagonal metal plates with metal strips, a 90° phase shift is achieved without using a phase shifter, realizing circularly polarized radiation in the microwave band while simplifying the complexity of the microwave feeding structure.

[0026] 2. In this invention, the millimeter-wave feeding structure is located directly below the metal floor, and the feeding path is arranged vertically. The microwave feeding structure passes through the through-hole reserved for the gap between the millimeter-wave radiating elements on the metal floor, and its bent metal probe extends horizontally. The feeding paths of the two frequency bands avoid each other in space, thus achieving good port isolation.

[0027] 3. This invention allows for the selective installation of a metal fence around the edge of the microwave radiating structure at the metal floor. The metal fence structure further improves the symmetry and front-to-back ratio of the antenna pattern, thereby enhancing the overall gain of the antenna. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a microwave millimeter-wave circularly polarized co-structure antenna according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of a microwave millimeter-wave circularly polarized co-structure antenna according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the millimeter-wave band feeding structure of a microwave millimeter-wave circularly polarized co-structure antenna according to an embodiment of the present invention;

[0031] Figure 4 The simulated S-parameter curves of the microwave millimeter-wave circularly polarized co-structure antenna in the microwave band are shown in the embodiment of the present invention.

[0032] Figure 5The simulated S-parameter curves of the microwave millimeter-wave circularly polarized co-structure antenna in the millimeter-wave band according to an embodiment of the present invention are shown.

[0033] Figure 6 The simulation curves of gain and axial ratio of the microwave millimeter-wave circularly polarized co-structure antenna in the microwave band are shown in the embodiment of the present invention.

[0034] Figure 7 The simulation curves of gain and axial ratio of the microwave millimeter-wave circularly polarized co-structure antenna in the millimeter-wave band are shown in the embodiment of the present invention.

[0035] Figure 8 The above are simulation results of the radiation pattern of the microwave and millimeter-wave circularly polarized co-structure antenna in the microwave band according to an embodiment of the present invention.

[0036] Figure 9 The simulation results of the radiation pattern of the microwave millimeter-wave circularly polarized co-structure antenna in the millimeter-wave band are shown in the embodiment of the present invention. Detailed Implementation

[0037] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0038] like Figure 1 As shown, the microwave and millimeter-wave dual-band circularly polarized common-structure antenna of this invention includes a millimeter-wave radiating structure 1, a microwave radiating structure 2, a millimeter-wave feeding structure 3, a microwave feeding structure 4, and a metal ground plane 5. The microwave radiating structure 2 is located at the center of the metal ground plane 5, and the millimeter-wave radiating structures 1 are symmetrically distributed around it. The millimeter-wave feeding structure 3 is located directly below the millimeter-wave radiating structure 1, and cascades two stages of equal-amplitude and equal-phase power dividers in the vertical direction, having one input port and four output ports. The microwave feeding structure 4 is inserted from below the metal ground plane 5, passing through a pre-reserved metal hole to feed the microwave radiating structure 2.

[0039] Figure 2The microwave and millimeter-wave dual-band circularly polarized co-structure antenna structure of this invention will be further described below. First, the millimeter-wave band antenna structure is described: the millimeter-wave band radiation structure includes four stepped partition waveguides 6, distributed on a metal floor 5 with fencing at the four corners. The top of each stepped partition waveguide 6 has a horizontally extending metal plate, and two metal plates located diagonally are connected by metal strips. The following explanation uses odd-even mode analysis to illustrate the circularly polarized radiation mechanism of the millimeter-wave band: Assuming the transmission mode at the port of the stepped partition waveguide 6 is TE10, the internal electric field can be considered as a superposition of odd and even modes. The stepped partition can significantly induce a change in the odd-mode electric field distribution, causing the odd-mode transmission mode to change to TE01. The stepped partition does not affect the even-mode electric field distribution, and the even-mode transmission mode remains TE10. Therefore, two orthogonal modes are generated at the top of the stepped septum waveguide 6. By designing the stepped septum parameters, the 90° phase difference generated by the orthogonal modes can be controlled, thereby synthesizing a stable circularly polarized wave.

[0040] Reference Figure 3 The millimeter-wave band feed structure is a waveguide power divider 9 composed of one H-plane T-junction power divider 7 and two E-plane T-junction power dividers 8 cascaded together. After the high-frequency signal is transmitted into the input port of the waveguide power divider 9, it generates an excitation with the same phase and amplitude at the ports of the four stepped partition waveguides 6.

[0041] The following describes the radiation and feeding structures of microwave band antennas: Figure 2 As shown, a bent metal probe 10 with angled bends is placed in the element spacing of a millimeter-wave waveguide array. After the microwave signal enters the coaxial line 11, antiphase surface currents are induced on the outer walls of the stepped partition waveguide 6 located on both sides of the probe. At this time, the outer walls of the stepped partition waveguide 6 in the millimeter-wave band are multiplexed as magnetic dipoles, and the two pairs of horizontal metal plates extending outward from the top are multiplexed as electric dipoles, forming a magnetoelectric dipole as the microwave band radiation structure. The horizontal metal plates at diagonal positions are connected by metal strips to form a 90° phase difference, realizing circularly polarized radiation in the microwave band.

[0042] To verify the feasibility of the microwave / millimeter-wave dual-band circularly polarized co-structure antenna of this invention, an example of a microwave / millimeter-wave dual-band circularly polarized co-structure antenna operating in the Sub-6 GHz and millimeter-wave bands was designed according to the technical solution provided in this invention. In the antenna example, a 50Ω coaxial cable is used as the microwave feed line. In the example antenna, the stepped partition waveguide height is 13mm, the length and width of the metal ground plane are both 40mm, and the height of the metal fence is 5mm. This antenna structure is an all-metal structure, meeting the processing requirements of additive manufacturing, and can be processed using 3D metal printing technology.

[0043] Figures 4 to 9The simulation parameters of the example antenna are presented. Considering both the -10dB impedance bandwidth and the 3dB axial ratio bandwidth, the test results show that the proposed antenna structure exhibits excellent wide impedance bandwidth characteristics and circular polarization radiation performance in both microwave and millimeter-wave bands, and also possesses good isolation between the two band structures. It should be noted that in the microwave band, circular polarization radiation with the opposite rotation direction can be generated by modifying the connection path of the metal strip (e.g., connecting another set of diagonal metal plates). Similarly, in the millimeter-wave band, circular polarization radiation with the opposite rotation direction can be generated by modifying the step direction of the partition.

[0044] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A microwave / millimeter-wave circularly polarized dual-band common-structure antenna, characterized in that, include: Metal floor (5); Millimeter-wave radiation structure (1) is symmetrically distributed at the center of the metal floor (5); The microwave radiation structure (2) is located at the center of the millimeter-wave radiation structure (1); The millimeter-wave feeding structure (3) is located below the metal floor (5) and uses a waveguide power divider to provide equal amplitude and equal phase excitation to the millimeter-wave radiating array elements; The microwave feeding structure (4) is inserted from below the metal floor (5), and the feeding path is the gap between the millimeter-wave radiation array elements, which feeds the microwave radiation structure (2).

2. The antenna according to claim 1, characterized in that, The millimeter-wave radiation array element is a stepped partition waveguide (6). The stepped partition divides the rectangular waveguide into two cavities of the same size, and the partitions are arranged in an axially symmetrical manner to achieve circular polarization radiation in the millimeter-wave band.

3. The antenna according to claim 2, characterized in that, Each stepped septum waveguide has an outwardly extending metal plate at the top, and two diagonally opposite metal plates are connected by a metal strip to achieve circularly polarized radiation in the microwave band.

4. The antenna according to claim 1, characterized in that, The millimeter-wave feed structure adopts an air-filled rectangular waveguide structure, and achieves multiple equal-amplitude and in-phase outputs by cascading multiple 1-to-2 power dividers in the vertical direction.

5. The antenna according to claim 4, characterized in that, The waveguide power divider (9) includes: A first-stage 1-to-2 power divider, the input port of which serves as the input port of the millimeter-wave feed structure; Two second-stage one-to-two power dividers have their input terminals connected to the two output ports of the first-stage one-to-two power divider, and their output ports are connected one-to-one to the millimeter-wave radiation structure (1) unit.

6. The antenna according to claim 1, characterized in that, The microwave feeding structure includes a bent metal probe (10) and a coaxial line (11); the bent metal probe (10) is disposed in the gap between the array elements of the millimeter-wave radiation structure (1), and the probe direction is perpendicular to the direction of the metal partition; the coaxial line (11) is inserted from the channel reserved in the metal floor (5), and its inner conductor is connected to the bent metal probe (10).

7. The antenna according to claim 1, characterized in that, Metal fences (12) are set at the four corners of the metal floor (5) to improve the circular polarization performance of the antenna.

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