A broadband omnidirectional circularly polarized antenna and a wireless communication device

Abstract

The present invention discloses a broadband omnidirectional circularly polarized antenna and a wireless communication device, which include a coaxial feeder, a grounding post, a zero-order resonance radiation unit located on the top-layer substrate, a half-mode substrate integrated waveguide unit located on the middle-layer substrate, and a quasi-circular ring radiation unit located on the bottom-layer substrate; the zero-order resonance radiation unit includes a top-layer circular Patch, a top-layer bent inductor line, and a top-layer outer ring, the half-mode substrate integrated waveguide unit includes a middle-layer circular Patch, a middle-layer bent inductor line, and a middle-layer outer ring, the quasi-circular ring radiation unit includes a bottom-layer circular Patch, four 1 / 4 arcs, and a microstrip arm. The antenna of the present invention realizes omnidirectional coverage of circular polarization in the range of 2.3 - 2.6 GHz, and the axial ratio performance is less than 3 dB in the range of 2.3 - 2.6 GHz.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency communication, and particularly to a broadband omnidirectional circularly polarized antenna and a wireless communication device. Background Art

[0002] Antenna polarization is an important index of antenna performance. In past communication systems, linear polarization was the main choice in antenna design. For example, in the base station communication systems of 2G - 5G, the antenna polarization mode adopted is ±45° linear polarization. However, the performance of linear polarization antennas in resisting multipath fading and interference is poor. Therefore, in fields with high performance requirements such as satellite, ship, broadcast communication, and navigation, the polarization mode of antennas generally adopts circular polarization, and circular polarization antennas have made extremely prominent contributions in the above fields.

[0003] In traditional circularly polarized antennas, the antenna generally adopts a directional design scheme with radiation in a certain direction. In the case where the communication direction is known, by using its narrow beam and high gain characteristics, the communication quality of the system is improved. However, in the vast majority of civilian communication fields, the communication direction is random and unpredictable, which has led to great limitations of directional antennas in civilian communication fields, mainly manifested as poor coverage performance, and the signal cannot cover the communication range omnidirectionally by 360°.

[0004] To solve the above problems, there are design schemes of various types of omnidirectional circularly polarized antennas in the prior art. In more traditional schemes, such as helical omnidirectional circular polarization, circularly polarized patch circular arrays, etc., can all achieve the omnidirectional circular polarization radiation characteristics. However, this type of antenna has a high profile, a large volume, and a heavy weight, and is greatly limited in many communication fields. In recent years, with the development of composite right - hand and left - hand transmission line (CRLH) technology, the development of miniaturized omnidirectional circularly polarized antennas has achieved breakthrough results. The omnidirectional circularly polarized antenna based on CRLH utilizes the characteristic of the zero - order resonator's electric field being vertically uniformly distributed, and uses it to excite the omnidirectional vertically polarized radiation characteristic. At the same time, a quasi - loop antenna is added on the ground of the zero - order resonator to achieve omnidirectional horizontal polarization, and make it have a 90° phase difference with the vertical polarization, thereby achieving the omnidirectional circular polarization characteristic. The CRLH omnidirectional circularly polarized antenna has size advantages such as a low profile and a small volume. However, due to the CRLH being a single - point resonance structure, the bandwidth is narrow. Therefore, in application scenarios with high requirements for bandwidth performance, this type of antenna is still greatly limited. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a broadband omnidirectional circularly polarized antenna and a wireless communication device.

[0006] The antenna of the present invention not only realizes the omnidirectional circular polarization radiation characteristic, but also has the low - profile characteristic of the antenna, and at the same time realizes the broadband and miniaturization of the antenna.

[0007] The present invention adopts the following technical solutions:

[0008] A broadband omnidirectional circularly polarized antenna includes a zero-order resonant radiation unit located on the top-layer substrate, a half-mode substrate integrated waveguide unit located on the middle-layer substrate, and a quasi-circular ring radiation unit located on the bottom-layer substrate;

[0009] The zero-order resonant radiation unit includes a top-layer circular Patch, a top-layer bent inductive line, and a top-layer outer ring. The top-layer circular Patch is connected to the top-layer outer ring through the top-layer bent inductive line, and the top-layer circular Patch is disposed within the top-layer outer ring;

[0010] The half-mode substrate integrated waveguide unit includes a middle-layer circular Patch, a middle-layer bent inductive line, and a middle-layer outer ring. The middle-layer circular Patch is connected to the middle-layer outer ring through the middle-layer bent inductive line, and the middle-layer circular Patch is arranged within the middle-layer outer ring;

[0011] The quasi-circular ring radiation unit includes a bottom-layer circular Patch, four 1 / 4 arcs, and microstrip arms. The four 1 / 4 arcs form a quasi-circular ring. The bottom-layer circular Patch constitutes the electrical ground of the entire antenna. The bottom-layer circular Patch is connected to the four 1 / 4 arcs through four microstrip arms respectively, and the bottom-layer circular Patch is disposed within the quasi-circular ring;

[0012] It further includes a coaxial feeder and ground posts. The inner conductor of the coaxial feeder sequentially passes through the bottom-layer circular Patch, the middle-layer circular Patch and is connected to the top-layer circular Patch. The outer conductor of the coaxial feeder is connected to the bottom-layer circular Patch and the middle-layer circular Patch;

[0013] The top-layer circular Patch is connected to the bottom-layer circular Patch through a ground post passing through the middle-layer circular Patch.

[0014] The top-layer substrate, the middle-layer substrate and the bottom-layer substrate are all connected to the coaxial feeder;

[0015] The centers of the top-layer circular Patch, the middle-layer circular Patch and the bottom-layer circular Patch are respectively at the central positions of the top-layer substrate, the middle-layer substrate and the bottom-layer substrate.

[0016] The top-layer substrate, the middle-layer substrate and the bottom-layer substrate are all circular.

[0017] There are four ground posts. Four metal vias are opened on both the top-layer and bottom-layer substrates for the ground posts to pass through and be connected, and an opening is provided on the middle-layer substrate for the ground posts to pass through.

[0018] The four grounding posts are symmetrically and periodically arranged around the center of the antenna.

[0019] The diameters of the top-layer outer ring, the middle-layer outer ring, and the bottom-layer quasi-ring are 29 mm, 18 mm, and 44 mm respectively.

[0020] A wireless communication device includes an input device and an output device, and both the input device and the output device are composed of the broadband omnidirectional circularly polarized antenna described above.

[0021] The present invention adopts the following technical solutions:

[0022] (1) The present invention improves the VSWR bandwidth of the center-fed structure and greatly broadens the VSWR bandwidth of the center-fed structure;

[0023] (2) The present invention uses the method of loading a half-mode substrate integrated waveguide to maintain the vertical polarization purity of the antenna and broaden the polarization bandwidth of the antenna;

[0024] (3) Compared with the helical or array implementation of the omnidirectional circularly polarized radiation characteristics, the present invention retains the advantages of low profile and small size;

[0025] (4) The present invention uses the outer conductor of the coaxial feeder shared by the half-mode substrate integrated waveguide as the grounding post without additional material cost. Description of the Drawings

[0026] Figure 1 is the overall structural schematic diagram of the present invention;

[0027] Figure 2 is Figure 1 the structural schematic diagram of the zero-order resonant radiation unit in

[0028] Figure 3 is Figure 1 the structural schematic diagram of the half-mode substrate integrated waveguide unit in

[0029] Figure 4 is Figure 1 the structural schematic diagram of the bottom-layer quasi-circular ring radiation unit in

[0030] Figure 5 is the echo loss simulation result diagram of the present invention;

[0031] Figure 6(a) is the result diagram of the main polarization - left-handed circular polarization pattern of the present invention;

[0032] Figure 6(b) is the structural diagram of the cross-polarization - right-handed circular polarization pattern of the present invention;

[0033] Figure 7 is the result diagram of the axial ratio of the present invention at 2.3 - 2.6 GHz. Detailed Embodiments

[0034] The present invention will be further described in detail below in conjunction with embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0035] Embodiment

[0036] As Figures 1-4 shown, a broadband omnidirectional circularly polarized antenna is assembled by a multi-layer PCB board structure. This embodiment is composed of three PCB boards that are spaced a certain distance apart and parallel to each other. The three PCB boards are circular, and their centers are on the same vertical line. The spacing distance between the three boards is determined according to the actual situation. It includes a zero-order resonant radiation unit 1 located on the top-layer substrate, a half-mode substrate integrated waveguide unit 3 located on the middle-layer substrate, and a quasi-circular ring radiation unit 4 located on the bottom-layer substrate.

[0037] The zero-order resonant radiation unit includes a top-layer circular Patch, a top-layer bent inductance line, and a top-layer outer ring. The top-layer circular Patch is connected to the top-layer outer ring through the top-layer bent inductance line, and the top-layer circular Patch is disposed inside the top-layer outer ring; there are four top-layer bent inductance lines, which are arranged at equal intervals between the top-layer circular Patch and the top-layer circular Patch. The introduction of the inductance bent line increases the equivalent inductance of the zero-order resonance, enhances the radiation efficiency of the zero-order resonance, and effectively reduces the area of the top-layer unit.

[0038] The centers of the circular Patch and the outer ring in the zero-order resonant radiation unit coincide with the center of the top-layer substrate.

[0039] The half-mode substrate integrated waveguide unit includes a middle-layer circular Patch, a middle-layer bent inductance line, and a middle-layer outer ring. The middle-layer circular Patch is connected to the middle-layer outer ring through four periodically arranged middle-layer bent inductance lines, and the middle-layer circular Patch is disposed inside the middle-layer outer ring, achieving miniaturization.

[0040] The centers of the middle-layer circular Patch and the middle-layer outer ring of the half-mode substrate integrated waveguide unit coincide with the center of the middle-layer substrate.

[0041] The quasi-circular ring radiation unit includes a bottom-layer circular Patch, four 1 / 4 arcs, and microstrip arms. The bottom-layer circular Patch forms the electrical ground of the entire antenna, and the structures that need to be grounded are all connected to the bottom-layer circular Patch. For example, the four periodically grounded posts of the top-layer zero-order resonant radiation unit and the coaxial outer conductor connected to the circular Patch of the middle-layer half-mode substrate integrated waveguide unit are finally electrically connected to the circular Patch on the bottom-layer quasi-circular ring radiation unit.

[0042] The underlying circular Patch is connected to four 1 / 4 arcs through four microstrip arms. In this embodiment, the microstrip arms are connected to one end of the arcs, and the underlying circular Patch is disposed within a quasi-circular ring;

[0043] The four 1 / 4 arcs form a quasi-circular ring antenna. The four 1 / 4 arcs are spaced at equal distances. This quasi-circular ring antenna is connected to the circular Patch ground through four microstrip arms and radiates an omnidirectional horizontally polarized electric field.

[0044] The center of the quasi-circular ring antenna and the center of the underlying circular Patch both coincide with the center of the underlying substrate.

[0045] This antenna further includes a coaxial feeder 5 and four ground posts 2. The ground posts are made of metal. The top substrate, the middle substrate, and the bottom substrate are each provided with five non-metallized vias, one of which is located at the center of each substrate.

[0046] Both the top substrate and the bottom substrate are provided with four metal vias for the ground posts to pass through and be connected. The middle substrate has openings for the ground posts to pass through.

[0047] The inner conductor of the coaxial feeder is used to feed the omnidirectional circularly polarized antenna. The inner conductor of the coaxial feeder passes through the non-metallized vias of the bottom layer and the middle layer and is connected to the patch center of the top layer zero-order resonance radiation unit. The connection method is welding or other methods such as metal-to-metal contact; the outer conductor of the coaxial feeder is connected to the underlying circular Patch and the middle layer circular Patch to form an omnidirectional vertically polarized radiator.

[0048] In this embodiment, the operating frequency band is 2.3 - 2.6 GHz, and the selected board material is FR-4. The dimension marking diagram of the corresponding omnidirectional circularly polarized antenna is as Figures 2-4 shown, and the specific parameters are as follows:

[0049] D1 = 29mm, D2 = 18mm, D3 = 44mm, d1 = 12mm, d2 = 4mm, d3 = 21mm, DS = 3.8mm,

[0050] H1 = H2 = H3 = 0.8mm.

[0051] For the specific basic dimensions, the dimensions of each layer of circular Patch and the outer circular ring vary with the frequency.

[0052] As Figure 5 shown, it is the S-parameter diagram of a broadband omnidirectional circularly polarized antenna provided by an embodiment of the present invention. The impedance matching within the passband is good, and the typical value of the return loss is above 10 dB.

[0053] As shown in FIGS. 6(a) and 6(b), it is the gain curve graph of a broadband omnidirectional circularly polarized antenna provided by an embodiment of the present invention. The gain is stable within the working frequency band of 2.3 - 2.6 GHz, and the cross-polarization performance is less than 15 dB.

[0054] As Figure 7 shown, it is the axial ratio curve graph of a broadband omnidirectional circularly polarized antenna provided by an example of the present invention. The axial ratio is less than 3 dB within the frequency band of 2.3 - 2.6 GHz

[0055] Embodiment 2

[0056] A wireless communication device includes an input device and an output device, and both the input device and the output device are composed of a broadband omnidirectional circularly polarized antenna of the present invention.

[0057] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent substitution methods and are all included in the protection scope of the present invention.

Claims

1. A broadband omnidirectional circularly polarized antenna, characterized in that It includes a zero-order resonant radiation unit located on the top-layer substrate, a half-mode substrate integrated waveguide unit located on the middle-layer substrate, and a quasi-circular ring radiation unit located on the bottom-layer substrate; The zero-order resonant radiation unit includes a top-layer circular Patch, a top-layer bent inductor line, and a top-layer outer ring. The top-layer circular Patch is connected to the top-layer outer ring through the top-layer bent inductor line. The top-layer circular Patch is arranged inside the top-layer outer ring. There are four top-layer bent inductor lines, which are arranged at equal intervals between the top-layer circular Patch and the top-layer circular Patch. The introduction of the bent inductor line increases the equivalent inductance of the zero-order resonance, enhances the radiation efficiency of the zero-order resonance, and effectively reduces the area of the top-layer unit; The half-mode substrate integrated waveguide unit includes a middle-layer circular Patch, a middle-layer bent inductor line, and a middle-layer outer ring. The middle-layer circular Patch is connected to the middle-layer outer ring through the middle-layer bent inductor line. The middle-layer circular Patch is arranged inside the middle-layer outer ring; The quasi-circular ring radiation unit includes a bottom-layer circular Patch, four 1 / 4 arcs, and microstrip arms. The four 1 / 4 arcs form a quasi-circular ring. The bottom-layer circular Patch constitutes the electrical ground of the entire antenna. The bottom-layer circular Patch is connected to the four 1 / 4 arcs through four microstrip arms respectively. The bottom-layer circular Patch is arranged inside the quasi-circular ring; It also includes a coaxial feeder and a grounding post. The inner conductor of the coaxial feeder sequentially passes through the bottom-layer circular Patch, the middle-layer circular Patch, and is connected to the top-layer circular Patch. The outer conductor of the coaxial feeder is connected to the bottom-layer circular Patch and the middle-layer circular Patch; The top-layer circular Patch is connected to the bottom-layer circular Patch through the grounding post passing through the middle-layer circular Patch.

2. The broadband omnidirectional circularly polarized antenna according to claim 1, wherein The top-layer substrate, the middle-layer substrate, and the bottom-layer substrate are all connected to the coaxial feeder; The centers of the top-layer circular Patch, the middle-layer circular Patch, and the bottom-layer circular Patch are respectively at the central positions of the top-layer substrate, the middle-layer substrate, and the bottom-layer substrate.

3. A broadband omnidirectional circularly polarized antenna according to claim 1, characterized in that, The top-layer substrate, the middle-layer substrate, and the bottom-layer substrate are all circular.

4. A broadband omnidirectional circularly polarized antenna according to claim 1, characterized in that, There are four grounding posts. The top-layer substrate and the bottom-layer substrate are both provided with four metal vias for the grounding posts to pass through and connect. The middle-layer substrate is provided with an opening for the grounding posts to pass through.

5. The omnidirectional broadband circularly polarized antenna according to claim 4, characterized in that, The four grounding posts are symmetrically arranged around the antenna center and periodically.

6. A broadband omnidirectional circularly polarized antenna according to claim 1, characterized in that The diameters of the top-layer outer ring, the middle-layer outer ring, and the bottom-layer quasi-circular ring are 29 mm, 18 mm, and 44 mm respectively.

7. A wireless communication device, characterized in that, It includes an input device and an output device. Both the input device and the output device are composed of the broadband omnidirectional circularly polarized antenna according to any one of claims 1-6.

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