A broadband dual-band multimode omnidirectional antenna

Abstract

This invention discloses a broadband dual-band multimode omnidirectional antenna, comprising a circular radiating patch, a dielectric layer, and a metal ground plane stacked sequentially. The upper surface of the dielectric layer is the circular radiating patch, and the lower surface is the metal ground plane. The circular radiating patch is divided into an inner circular radiating patch and an outer annular radiating patch, with an annular slot and an annular metal wall disposed between the inner circular radiating patch and the outer annular radiating patch. A coaxial probe and an arc-shaped slot are disposed at the center of the inner circular radiating patch. The coaxial probe is used to suppress the generation of non-omnidirectional modes while exciting omnidirectional modes. The arc-shaped slot for impedance matching is etched into the inner circular radiating patch. This invention improves the distortion of the higher-order mode radiation pattern and features a simple structure, dual-band broadband, and omnidirectional radiation.

Description

Technical Field

[0001] This invention belongs to the field of indoor mobile communication technology, specifically relating to a broadband dual-band multimode omnidirectional antenna. Background Technology

[0002] In indoor mobile communication systems, passive devices in indoor distributed system terminals are typically omnidirectional antennas, which are usually attached to the ceiling. Considering practical applications, single-frequency omnidirectional antennas are no longer sufficient. Therefore, multi-band, broadband omnidirectional antennas with good radiation characteristics are currently a research hotspot. Microstrip antennas are lightweight, easy to integrate, and easy to fabricate; however, traditional microstrip antennas have narrow bandwidths, which cannot meet their application requirements.

[0003] In the prior art, application document CN 109546335 B discloses a method of achieving wideband antenna by using a stacked two-layer radiating structure; application document CN 114361773 A discloses a method of achieving wideband antenna by introducing gradient grooves at the edges of intersecting substrates. These antennas suffer from problems such as high profile, difficult installation, and complex feeding structures. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the present invention aims to provide a broadband dual-band multimode omnidirectional antenna. Based on cavity theory analysis and the idea of ​​multimode fusion, it improves the distorted high-order mode radiation pattern and has the characteristics of simple structure, dual-band broadband and omnidirectional radiation.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A broadband dual-band multimode omnidirectional antenna includes a circular radiating patch, a dielectric layer, and a metal ground plane stacked sequentially.

[0007] The circular radiating patch includes a concentric inner circular radiating patch and an outer annular radiating patch. There is a gap between the outer edge of the inner circular radiating patch and the inner edge of the outer annular radiating patch. An annular metal wall is disposed within this gap, and there is an annular gap between the annular metal wall and the inner edge of the outer annular radiating patch. A coaxial probe is disposed through the center of the inner circular radiating patch. Several centrally symmetrical arc-shaped gaps are etched on the inner circular radiating patch. The coaxial probe is used to suppress the generation of non-omnidirectional modes while exciting omnidirectional modes. The arc-shaped gaps are used for impedance matching.

[0008] The inner side of the annular metal wall is closely attached to the inner circular radiating patch, and the outer side is separated from the outer annular radiating patch by an annular gap. The bottom is immediately connected to the upper layer of the dielectric layer, and the upper part exceeds the inner circular radiating patch and the outer annular radiating patch by a certain height.

[0009] Four arc-shaped gaps are provided, forming a cross shape; the arc-shaped gaps have a fan-shaped structure.

[0010] An annular metal wall is loaded onto the dielectric layer for impedance matching and pattern improvement.

[0011] The gap between the inner circular radiating patch and the outer annular radiating patch is fitted with an annular slot to broaden the bandwidth; an annular metal wall is loaded on the dielectric layer for impedance matching and pattern improvement.

[0012] The arc-shaped gap and the annular gap are kept on the same horizontal plane, and are rotated and etched sequentially around the center of the inner circular metal patch, with a rotation angle of 90°.

[0013] The coaxial probe is located at the center of the four sets of arc-shaped slits and is used to directly feed electricity to the circular radiating patch.

[0014] The inner circular radiating patch, the outer annular radiating patch, the annular gap, and the annular metal wall all share the same center.

[0015] The width of the annular metal wall is less than the difference between the inner radius of the outer annular radiating patch and the inner radius of the inner circular radiating patch, in order to improve the high-frequency radiation pattern of the antenna.

[0016] The top of the annular metal wall is provided with four mounting holes, which are placed symmetrically on the horizontal and vertical axes respectively.

[0017] The width of the annular gap is equal to the difference between the inner radius of the outer annular radiating patch and the inner radius of the inner circular radiating patch, minus the width of the annular metal wall.

[0018] The outer diameter of the external annular radiant patch is smaller than the outer diameter of the dielectric layer and the metal floor.

[0019] The outer diameters of the dielectric layer and the metal floor are equal.

[0020] The annular metal wall has a height of Hr and is mounted on the dielectric layer. The inner conductor of the coaxial probe is connected to the inner circular radiating patch, and its outer conductor is connected to the metal ground plane. The metal ground plane is circular with a diameter of Rg. The mounting hole is a non-metallized via. The dielectric layer is composed of a dielectric plate with a thickness of H and a relative permittivity of εr, wherein 1.26λ0≤Rg≤1.35λ0, 0.04λ≤R≤0.1λ, 0.02λ0<H<0.03λ0, and 2.7≤εr≤3.2. The center frequency of the antenna operating band has a free space wavelength of λ0. The inner circular radiating patch has a diameter of R1, and the outer annular radiating patch has a diameter of R2, wherein 0.71λ0≤R1≤0.74λ0 and 1.22λ0≤R2≤1.3λ0. The width of the annular gap is Rs, wherein 0.04λ0≤Rs≤0.05λ0.

[0021] The width of the annular metal wall is Rr, and the height is Hr, where 0.04λ0≤Rr≤0.1λ0 and 0.03λ0≤Hr≤0.07λ0.

[0022] The distance from the inner edge of the arc-shaped gap to the center is R3, the distance from the inner edge of the arc-shaped gap to the outer edge is R4, and the opening angle of the arc-shaped gap is α; where 0.018λ0≤R3≤0.027λ0, 0.05λ0≤R4≤0.08λ0, and 25°≤α≤43°.

[0023] The beneficial effects of this invention are:

[0024] This invention suppresses the generation of non-omnidirectional modes by feeding power at the center of a circular patch, exciting only omnidirectional modes; it widens the operating bandwidth by adjusting the resonant point through cutting annular slots; it improves the antenna's impedance and radiation pattern by loading an annular metal wall; and it further improves the antenna's impedance by cutting arc-shaped slots on the radiating patch to achieve impedance matching. Ultimately, the antenna operates in dual-frequency mode and exhibits wideband omnidirectional characteristics. Attached Figure Description

[0025] Figure 1 This is a schematic cross-sectional view of a broadband dual-band omnidirectional microstrip antenna according to the present invention.

[0026] Figure 2 This is a top view of a broadband dual-band omnidirectional microstrip antenna according to the present invention.

[0027] Figure 3 This is a 3D structural diagram of a broadband dual-band omnidirectional microstrip antenna according to the present invention.

[0028] Figure 4 This is a simulation and measured return loss curve of a broadband dual-band omnidirectional microstrip antenna according to the present invention.

[0029] Figure 5 (a) The XOZ radiation pattern of a broadband dual-band omnidirectional microstrip antenna of the present invention, simulated and tested at 2.7 GHz; Figure 5 (b) is the XOY plane radiation pattern of a broadband dual-band omnidirectional microstrip antenna of the present invention, simulated and tested at 2.7 GHz.

[0030] Figure 6 (a) is the simulated and tested XOZ radiation pattern of a broadband dual-band omnidirectional microstrip antenna of the present invention at 5.4 GHz; Figure 6 (b) is the XOY plane radiation pattern of a broadband dual-frequency omnidirectional microstrip antenna of the present invention, simulated and tested at 5.4 GHz.

[0031] Figure 7 This is a simulation and measured peak gain curve of a broadband dual-band omnidirectional microstrip antenna according to the present invention.

[0032] in, Figures 1 to 3 In the diagram, 1-dielectric layer, 2-inner circular radiating patch, 3-outer annular radiating patch, 4-annular gap, 5-annular metal wall, 6-arc-shaped gap, 7-mounting hole, 8-coaxial probe, 9-metal floor. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] Example 1

[0035] Please see Figure 1 , Figure 2 and Figure 3 A broadband dual-band multimode omnidirectional antenna, based on cavity theory analysis and multimode fusion, includes an inner circular radiating patch 2 and an outer annular radiating patch 3, a dielectric layer 1, and a metal ground plane 9 stacked sequentially; it also includes mounting holes 7 and coaxial probes 8; the circular radiating patch 2 and the annular radiating patch 3 are divided by annular gaps 4 and annular metal walls 5; the bottom of the annular metal wall 5 is located on the upper layer of the dielectric layer and is on the same horizontal plane as the radiating patch while exceeding it by a certain height; the inner side of the annular metal wall 5 is close to the edge of the inner circular radiating patch 2, and the outer side is separated from the inner edge of the outer annular radiating patch 3 by a gap, i.e., the annular gap 4; the arc-shaped gaps 6 are evenly distributed around the center; the mounting holes 7 and coaxial probes 8 are both non-metallic through holes.

[0036] A coaxial probe 8 is loaded at the center of the circular radiating patch to suppress the generation of non-omnidirectional modes, sequentially exciting the antenna's omnidirectional modes CM1, CM2, CM3, and CM4 only in the designed low-frequency and high-frequency bands. The electric field direction of these four modes changes only radially from the radiating patch. An annular slot 4 is etched at the electric field zero points of CM2 and CM4 to extend the current paths of CM2 and CM4, thereby lowering the resonant frequencies of these two modes and bringing them closer to CM1 and CM3, thus widening the operating bandwidth in dual-frequency operation. An annular metal wall 5 is used to change the current distribution of the higher-order modes CM3 and CM4, drawing the originally horizontally opposite currents to the vertically mounted annular metal wall, thereby suppressing current cancellation in the horizontal direction and improving the gain of the high-frequency radiation pattern pits. Furthermore, adjusting the height of the annular metal wall 5 can reduce the radiation pits at high frequencies. An arc-shaped slot 6 acts as a small capacitor connected in parallel near the feed point to improve the antenna's capacitive-inductive properties, thus achieving impedance matching.

[0037] Example 2

[0038] Based on the above structure, the coaxial probe 8 is located at the center of the circular radiating patch to excite the omnidirectional mode of the antenna while suppressing the generation of non-omnidirectional modes.

[0039] Example 3

[0040] Based on the above structure, the inner circular radiating patch 2, the outer annular radiating patch 3, the annular gap 4, and the annular metal wall 5 are all concentric, ensuring the symmetry of the antenna structure.

[0041] Example 4

[0042] Based on the above structure, the width of the annular metal wall 5 is less than the difference between the inner radius of the outer annular radiating patch 3 and the inner radius of the inner circular radiating patch 2. The annular metal wall 5 is used to improve the high-frequency radiation pattern.

[0043] Example 5

[0044] Based on the above structure, the width of the annular gap 4 is exactly equal to the difference between the inner radius of the outer annular radiating patch 3 and the inner radius of the inner circular radiating patch 2, minus the width of the annular metal wall 5. The annular gap 4 is used to achieve wideband operation of the antenna.

[0045] Example 6

[0046] Based on the above structure, the outer diameter of the outer annular radiating patch 3 is smaller than the outer diameter of the dielectric layer 1 and the metal floor 9, so that the radiating patch can be printed on the dielectric layer.

[0047] Example 7

[0048] Based on the above structure, the outer diameters of the dielectric layer 1 and the metal floor 9 are equal.

[0049] Example 8

[0050] Based on the above structure, the annular metal wall 5 has a height of Hr and is installed on the medium layer.

[0051] Example 9

[0052] Based on the above structure, the inner conductor of the feed connector of the coaxial probe 8 is connected to the inner circular radiating patch 2, and its outer conductor is connected to the metal ground plate 9; the metal ground plate 9 is circular with a diameter of Rg; the mounting hole 7 is a non-metallized via with a radius of R; the dielectric layer 1 is composed of a dielectric plate with a thickness of H and a relative permittivity of εr, wherein 1.26λ0≤Rg≤1.35λ0, 0.04λ≤R≤0.1λ, 0.02λ0<H<0.03λ0λ, and 2.7≤εr≤3.2.

[0053] Test case

[0054] A broadband dual-band multimode omnidirectional antenna includes, in sequence, circular radiating patches (including an inner circular radiating patch 2 and an outer circular radiating patch 3 separated by an annular slot 4 and an annular metal wall 5), a dielectric layer 1, and a metal ground plane 9; it also includes a coaxial probe 8, an annular metal wall 5, and mounting holes 7. The circular radiating patches 2 are respectively etched with an annular slot 4 for widening the bandwidth and an arc-shaped slot 6 for impedance matching. The annular metal wall 5 for impedance matching and improving the radiation pattern is loaded onto the dielectric layer 1. The dielectric layer 1 is designed with mounting holes 7 for mounting the annular metal wall 5. The circular radiating patches 2 are directly fed by the coaxial probe 8 to excite the desired omnidirectional mode. The metal patch is printed on the upper surface of the dielectric substrate, and the metal floor is printed on the lower surface of the dielectric substrate. The inner circular radiating patch 2 has a diameter of R1, and the outer annular radiating patch 3 has a width of R2. The center of the annular gap is located at the center of the patch, and the width is Rs, dividing the circular radiating patch into two parts: the inner circular radiating patch 2 and the outer annular radiating patch 3. The annular metal wall is located between the gaps of the metal patches, and the width is Rr. The inner side is tightly attached to the circular radiating patch, and the outer side is separated from the annular radiating patch by a certain gap. The bottom layer is immediately adjacent to the upper layer of the dielectric layer, and the upper part exceeds the dielectric substrate by a certain height Hr; the arc-shaped gaps 6 consist of four sets, which are kept on the same horizontal plane as the annular gaps 4, and are sequentially rotated and etched around the center of the circular metal patch at a rotation angle of 90°. The distance from the inner edge of the arc-shaped gap to the center of the circle is R3, and the distance from the inner edge of the arc-shaped gap 6 to the outer edge is R4. The opening angle is α; the annular metal wall 5 has four mounting holes for fixing and is placed symmetrically; the power supply connector is a coaxial connector, with its inner conductor connected to the microstrip and its outer conductor connected to the metal ground plane; the metal ground plane is circular with a diameter of Rg; the thickness of the dielectric substrate is H, and the relative permittivity is εr. Wherein, 0.71λ0≤R1≤0.74λ0, 1.22λ0≤R2≤1.3λ0, 0.04λ0≤Rs≤0.05λ0, 0.04λ0≤Rr≤0.1λ0, 0.03λ0≤Hr≤0.07λ0, 0.018λ0≤R3≤0.027λ0, 0.05λ0≤R4≤0.08λ0, 25°≤α≤43°, and 2.7≤εr≤3.2.

[0055] To further illustrate the beneficial effects of this invention, simulation software and testing methods were used to simulate and test the port reflection coefficient, antenna pattern, and gain of the antennas in the above experimental examples. The test results are as follows: Figures 4 to 7 As shown.

[0056] Figure 4 This is a curve showing the port reflection coefficient as a function of operating frequency, obtained from antenna simulation and testing of the experimental example. From... Figure 4As can be seen, dual resonances occurred at both low and high frequencies, and the port exhibited good broadband characteristics. Simulation results show that the low-frequency band with a port reflection coefficient below -10dB is 2.50GHz-2.90GHz, i.e., an impedance bandwidth of 13.8%, and the high-frequency band with a port reflection coefficient below -10dB is 4.93GHz-5.74GHz, i.e., an impedance bandwidth of 14.1%. Test results show that the low-frequency band with a port reflection coefficient below -10dB is 2.58GHz-2.92GHz, i.e., an impedance bandwidth of 11.9%, and the high-frequency band with a port reflection coefficient below -10dB is 5.10GHz-5.79GHz, i.e., an impedance bandwidth of 12.5%. The measured results agree well with the simulation results, demonstrating the excellent dual-band broadband operation characteristics of the multi-mode fusion omnidirectional antenna.

[0057] Figure 5 The figures show the radiation patterns of the XOZ and XOY planes at low frequencies during simulation and testing of the experimental example. (a) shows the simulation and testing results for the XOZ plane at 2.7 GHz; (b) shows the simulation and testing results for the XOY plane at 2.7 GHz. As can be seen from the figures, the main polarization patterns in the simulation and testing are basically consistent, and good cross-polarization is achieved. The antenna obtains an omnidirectional radiation pattern in the XOY plane at low frequencies.

[0058] Figure 6 The diagrams show the low-frequency XOZ and XOY plane radiation patterns during simulation and testing of the experimental examples. (a) shows the simulation and testing results for the XOZ plane at 5.4 GHz; (b) shows the simulation and testing results for the XOY plane at 5.4 GHz. Figure 6 As can be seen, the main polarization patterns of the simulation and the test are basically the same, and the antenna obtains an omnidirectional radiation pattern in the XOY plane at high frequency.

[0059] Figure 7 As shown in the figure, the simulated and tested gain of the antenna in the 2.63GHz-2.89GHz frequency band is 6.4dBi, and the tested average gain is 5.6dBi; in the 5.18GHz-5.72GHz frequency band, the simulated average peak gain is 3.8dBi, and the tested average gain is 3.7dBi.

[0060] In summary, this invention provides a broadband dual-band multimode omnidirectional antenna. The coaxial feed is located at the center of the patch to suppress the generation of non-omnidirectional modes, and the antenna's omnidirectional modes CM1, CM2, CM3, and CM4 are excited sequentially only in the relevant low-frequency and high-frequency bands. Annular slots 4 are etched at the electric field zeros of CM2 and CM4 to extend the current paths of CM2 and CM4, thereby lowering the resonant frequencies of these two modes and bringing them closer to CM1 and CM3, thus widening the operating bandwidth in dual-band operation. Arc-shaped slots 6 are distributed around the feed point to introduce parallel capacitors for antenna impedance matching. By adjusting the parameters of the arc-shaped slots 6, the antenna can achieve a reflection coefficient below -10dB in the designed dual-band operation. An annular metal wall 5 is used to reduce radiation pits during high-frequency operation. By changing the current distribution of CM3 and CM4, the currents that were originally in opposite directions in the horizontal direction are drawn to the vertically mounted annular metal wall 5, thereby suppressing current cancellation in the horizontal direction and improving the radiation pit gain of higher-order modes.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A broadband dual-band multimode omnidirectional antenna, characterized in that, It includes a circular radiating patch, a dielectric layer (1), and a metal floor (9) stacked in sequence. The circular radiating patch includes a concentric inner circular radiating patch (2) and an outer annular radiating patch (3). There is a gap between the outer edge of the inner circular radiating patch (2) and the inner edge of the outer annular radiating patch (3). An annular metal wall (5) is set in the gap, and there is an annular gap (4) between the annular metal wall (5) and the inner edge of the outer annular radiating patch (3). A coaxial probe (8) is set through the center of the inner circular radiating patch (2). Several centrally symmetrical arc-shaped gaps (6) are etched on the inner circular radiating patch (2). The coaxial probe (8) is used to suppress the generation of non-omnidirectional modes and excite omnidirectional modes. The arc-shaped gaps (6) are used for impedance matching. The inner side of the annular metal wall (5) is closely attached to the inner circular radiation patch (2), and the outer side is separated from the outer annular radiation patch (3) by an annular gap (4). The bottom is closely attached to the upper layer of the dielectric layer (1), and the upper part exceeds the inner circular radiation patch (2) and the outer annular radiation patch (3) by a certain height.

2. The broadband dual-band multimode omnidirectional antenna according to claim 1, characterized in that, Four arc-shaped gaps (6) are provided, and the arc-shaped gaps (6) are fan-shaped structures.

3. A broadband dual-band multimode omnidirectional antenna according to claim 2, characterized in that, The arc-shaped slit (6) and the annular slit (4) are kept on the same horizontal plane and are rotated and etched sequentially around the center of the inner circular radiating patch (2) at a rotation angle of 90°.

4. A broadband dual-band multimode omnidirectional antenna according to claim 3, characterized in that, The coaxial probe (8) is located at the center of the four sets of arc-shaped slits (6) and is used to directly feed electricity to the circular radiation patch.

5. A broadband dual-band multimode omnidirectional antenna according to claim 1, characterized in that, The inner circular radiating patch (2), the outer annular radiating patch (3), the annular gap (4), and the annular metal wall (5) are all concentric.

6. A broadband dual-band multimode omnidirectional antenna according to claim 1, characterized in that, The width of the annular metal wall (5) is less than the difference between the inner radius of the outer annular radiating patch (3) and the inner radius of the inner circular radiating patch (2), in order to improve the high-frequency radiation pattern of the antenna. The top of the annular metal wall (5) is provided with four mounting holes (7), which are placed symmetrically on the horizontal axis and the vertical axis respectively. The width of the annular gap (4) is equal to the difference between the inner radius of the outer annular radiating patch (3) and the inner radius of the inner circular radiating patch (2) minus the width of the annular metal wall (5).

7. A broadband dual-band multimode omnidirectional antenna according to claim 6, characterized in that, The outer diameter of the external annular radiating patch (3) is smaller than the outer diameter of the dielectric layer (1) and the metal floor (9); The outer diameters of the medium layer (1) and the metal floor (9) are equal.

8. A broadband dual-band multimode omnidirectional antenna according to claim 6, characterized in that, The annular metal wall (5) has a height of Hr and is mounted on the dielectric layer (1). The inner conductor of the coaxial probe (8) is connected to the inner circular radiating patch (2), and its outer conductor is connected to the metal floor (9). The metal floor (9) is circular with a diameter of Rg. The mounting hole (7) is a non-metallized via. The dielectric layer (1) is composed of a dielectric plate with a thickness of H and a relative permittivity of εr, where 1.26λ0≤Rg≤1.35λ0, 0.04 λ≤R≤0.1λ, 0.02λ0<H<0.03λ0, 2.7≤εr≤3.2; where the center frequency of the antenna operating band has a free space wavelength of λ0; the diameter of the inner circular radiating patch (2) is R1, and the diameter of the outer annular radiating patch (3) is R2, where 0.71λ0≤R1≤0.74λ0, 1.22λ0≤R2≤1.3λ0; the width of the annular gap (4) is Rs, where 0.04λ0≤Rs≤0.05λ0; The width of the annular metal wall (5) is Rr and the height is Hr, where 0.04λ0≤Rr≤0.1λ0 and 0.03λ0≤Hr≤0.07λ0.

9. A broadband dual-band multimode omnidirectional antenna according to claim 1, characterized in that, The distance from the inner edge of the arc-shaped slit (6) to the center is R3, the distance from the inner edge of the arc-shaped slit (6) to the outer edge is R4, and the opening angle of the arc-shaped slit (6) is α; where 0.018λ0≤R3≤0.027λ0, 0.05λ0≤R4≤0.08λ0, and 25°≤α≤43°.

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