Reconfigurable filter antenna based on directional pattern of origami structure

Abstract

The application discloses a directional pattern reconfigurable filtering antenna based on a paper folding structure, comprising an antenna radiation structure arranged on an antenna floor, wherein the antenna radiation structure comprises a paper folding structure in the shape of a cuboid, a radiation patch, a monopole radiation patch, a metal branch, a filtering feed line, a first dielectric substrate, a second dielectric substrate and a coaxial feed line. The paper folding structure serves as a radiation mode switching structure, realizing switching between an omnidirectional radiation mode and a directional radiation mode. A hairpin microstrip line and a coupling microstrip line structure are adopted as filtering structures, and a feeding structure is composed of the filtering feed line and a rectangular metal branch. The application solves the problems of additional insertion loss caused by switching the radiation mode by using a PIN diode, increased manufacturing cost and complexity caused by introducing a bias circuit and the problem of being unable to suppress out-of-band interference signals.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, and further relates to a pattern-reconfigurable filter antenna based on an origami structure in the field of electromagnetic fields and microwave technology. This invention can operate in both directional and omnidirectional radiation modes, and can be practically applied to disaster relief, geological disasters, and other situations requiring rapid deployment of communication nodes. Background Technology

[0002] With the rapid development of modern communication systems, pattern-reconfigurable antennas have the characteristic of dynamically changing their radiation modes. Filtered antennas are a novel structure in wireless communication technology in recent years, integrating the functions of traditional antennas and filters. By suppressing signals outside the frequency band, signal interference can be reduced and signal quality improved. By changing the radiation mode, antenna performance can be optimized according to the actual communication environment and requirements. Furthermore, optimizing the radiation mode can improve the spectral efficiency of the wireless communication system.

[0003] Nanjing University of Aeronautics and Astronautics proposed a pattern-reconfigurable filter antenna using a microstrip structure in its patent application "A Pattern-Reconfigurable Filter Antenna" (Application No.: 201810023131.X, Publication No.: CN 108258405 A). This antenna includes a dielectric substrate and filter antenna modules and a control module located above and below the substrate, respectively. When both PIN diodes in the control module are in the off state, the radiation direction of the pattern-reconfigurable filter antenna is omnidirectional; when either PIN diode in the control module is in the on state, the radiation direction of the pattern-reconfigurable filter antenna is from the on PIN diode towards the transmitting antenna. Although this antenna structure has filtering characteristics and a wide bandwidth, it still has two shortcomings: First, using PIN diodes to switch the radiation mode introduces additional insertion loss. Second, the antenna fabrication requires the introduction of a bias circuit, increasing manufacturing cost and complexity.

[0004] South China Normal University proposed a pattern-reconfigurable microstrip slot antenna in its patent application "A Pattern-Reconfigurable Microstrip Slot Antenna" (Application No.: 201810047767.8, Publication No.: CN 108232443 A). This antenna consists of a dielectric substrate, a feed network, and a ground plane. The antenna uses digital electronics to control the DC bias voltage, thereby controlling the on / off state of four diode switches to achieve switching between different operating modes. However, this antenna structure and performance have three shortcomings: First, the use of diode switches introduces insertion loss. Second, the use of electronic switches and bias circuits increases manufacturing complexity. Third, the antenna does not use a filtering structure, making it unable to suppress out-of-band interference signals.

[0005] Currently, pattern-reconfigurable antennas face two main challenges: 1. The selection of switching modes. Electronic switching introduces insertion loss, affecting the overall antenna performance and hindering rapid deployment. 2. The introduction of bias circuitry complicates the overall structure and increases manufacturing costs. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the prior art by providing a pattern-reconfigurable filter antenna based on an origami structure. This antenna solves the problems of additional insertion loss caused by using PIN diodes to switch radiation modes, increased manufacturing costs and complexity due to the introduction of bias circuits, and the inability to suppress out-of-band interference signals.

[0007] The technical approach to achieving the objective of this invention is as follows: This invention employs a paper-folding structure as the radiation mode switching structure. Each of the four sides of the paper-folding structure is composed of four isosceles trapezoids and four isosceles right triangles. The edges of the isosceles trapezoids and isosceles right triangles are defined as creases in the paper-folding structure. When not folded, this invention operates in omnidirectional radiation mode; while when folded inwards by 90° along the creases, this invention operates in directional radiation mode. The radiation mode switching method is completed solely within the paper-folding structure and does not involve additional electronic components, thereby solving the problems of existing technologies that use PIN diodes to achieve pattern switching, resulting in complex antenna structures, high manufacturing costs, and insertion losses. This invention uses hairpin-type microstrip lines and coupled microstrip lines as filtering structures. The hairpin-type microstrip lines and coupled microstrip lines generate radiation nulls at the upper and lower edges of the passband, respectively, to suppress out-of-band signals. This invention adopts a fusion design of the filtering structure and antenna structure, eliminating the need for additional filter design, thereby solving the problem of existing technologies that cascade filters at the antenna feed port, resulting in large antenna size. The feeding structure in this invention consists of a filtered feed line connected to a rectangular metal stub. The filtered feed line provides coupled feeding to the square radiating patch, while the rectangular metal stub provides direct feeding to the monopole radiating patch. The filtered feed line structure and the rectangular metal stub share a single coaxial feeding port, eliminating the need for two separate ports to feed the square and monopole radiating patches. This solves the problem of existing technologies requiring additional feeding ports on the antenna, resulting in complex antenna feeding structures and poor practicality.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows.

[0009] The pattern-reconfigurable filter antenna of the present invention includes an antenna radiating structure disposed on an antenna floor. The antenna radiating structure includes a cuboid origami structure, a radiating patch, a monopole radiating patch, a metal stub, a filter feed line, a first dielectric substrate, a second dielectric substrate, and a coaxial feed line. The origami structure includes a first dielectric substrate placed on the left side of its upper surface and a second dielectric substrate placed on the left side of its lower surface, a monopole radiating patch attached to the right side of its right surface, and a metal stub on the right side of its lower surface. The radiating patch is attached to the right side of the upper surface of the first dielectric substrate. The filter feed line includes a hairpin microstrip line and a coupled microstrip line.

[0010] The invention has the following advantages compared to the prior art:

[0011] First, the present invention uses a paper-folding structure as the radiation mode switching structure, which overcomes the shortcomings of the prior art that uses PIN tubes to achieve pattern switching, which makes the antenna structure complex, has high manufacturing cost, and introduces insertion loss. This invention has the advantages of low cost, lightweight and high efficiency.

[0012] Secondly, by employing hairpin-type microstrip lines and coupled microstrip line structures as filtering structures, this invention overcomes the shortcomings of existing technologies that cascade filters at the antenna feed port, resulting in a large antenna size. This gives the invention the advantages of a compact structure and miniaturization.

[0013] Third, the feeding structure in this invention is composed of a filter feed line and a rectangular metal stub, which overcomes the shortcomings of the prior art that adds an extra feed port to the antenna, making the antenna feeding structure complex and impractical. This invention has the advantages of simple design and easy integration. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention in its unfolded state;

[0015] Figure 2 This is a front view of one of the four sides of the origami structure of the present invention;

[0016] Figure 3 This is a schematic diagram of the origami structure in Embodiment 1 of the present invention;

[0017] Figure 4 Front view of Embodiment 2 of the present invention;

[0018] Figure 5 This is a schematic diagram of Embodiment 3 of the present invention;

[0019] Figure 6 This is a schematic diagram of the structure of Embodiment 4 of the present invention in its unfolded state;

[0020] Figure 7 This is a schematic diagram of the structure of Embodiment 5 of the present invention in a folded state;

[0021] Figure 8 This is a simulation diagram of the performance of S11 in the unfolded state of Embodiment 4 of the present invention;

[0022] Figure 9 This is a simulation diagram of the radiation direction at 0.7 GHz in Embodiment 4 of the present invention;

[0023] Figure 10 This is a simulation diagram of the performance of S11 and Realized gain in the folded state of Embodiment 5 of the present invention;

[0024] Figure 11 This is a simulation diagram of the radiation direction at 2.45 GHz in Embodiment 5 of the present invention. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] See attached document Figure 1 The overall structure of the present invention will be described in further detail below.

[0027] This invention provides an antenna radiation structure on an antenna ground plane 7, wherein the antenna ground plane 7 is a metal cube or cuboid. In an embodiment of this invention, the antenna ground plane 7 is a copper cube with dimensions of 120mm × 120mm × 1mm.

[0028] The antenna radiation structure includes a paper-folding structure 1, a radiating patch 2, a monopole radiating patch 3, a metal stub 4, a filter feed line 5, a first dielectric substrate 61, a second dielectric substrate 62, and a coaxial feed line 8.

[0029] The origami structure 1 is made of any one of paper, flexible material, or plastic. In this embodiment, a paper material with dimensions of 145mm × 100mm × 100mm is used, including a first dielectric substrate 61 placed on the left side of its upper surface, a second dielectric substrate 62 placed on the left side of its lower surface, a monopole radiating patch 3 pasted on the right side, and a metal branch 4 on the right side of its lower surface.

[0030] The radiating patch 2 is a square made of metallic material, and is pasted on the right side of the upper surface of the first dielectric substrate 61. The side length of the square is:

[0031]

[0032] Where l is the side length of the square, c is the speed of light in free space, f0 is the center frequency of the directional radiation mode, and ε eThe effective dielectric constant is specified. In the embodiments of the present invention, the radiating patch 2 is a square made of copper metal, with dimensions of 35mm × 35mm, and is located 10.5mm from the right edge of the first dielectric substrate 61.

[0033] The monopole radiating patch 3 is a rectangular piece of metal and is pasted onto the center area of ​​the right surface of the origami structure 1. The longer side of the rectangle is:

[0034]

[0035] Wherein, l0 is the longer side of the rectangle, and f1 is the center frequency of the omnidirectional radiation mode. In the embodiment of the present invention, the monopole radiating patch 3 is a rectangle made of copper metal, with a longer side of 100mm and a shorter side of 30mm.

[0036] In this invention, the first dielectric substrate 61 and the second dielectric substrate 62 are made of the same material and have the same dimensions. The relative permittivity is 3.55, the thickness is 2mm, the dielectric loss is 0.0027, and the dimensions are 100mm×100mm×2mm.

[0037] Example 1: Combination Figure 1 The structural diagram and Figure 2 The origami structure of the present invention is shown in a front view of one of the four sides, which further describes Embodiment 1. Figure 2 The side view described is rectangular, composed of a first isosceles right triangle 11, a second isosceles right triangle 12, a third isosceles right triangle 13, a fourth isosceles right triangle 14, a first isosceles trapezoid 15, a second isosceles trapezoid 16, a third isosceles trapezoid 17, and a fourth isosceles trapezoid 18. The right-angled sides of the isosceles right triangles connect to the hypotenuses of the isosceles trapezoids, forming creases that allow the origami structure 1 to fold and deform along these creases, enabling it to have both fully unfolded and fully folded configurations. Each isosceles right triangle has a right-angled side length of 50 mm and two hypotenuses lengths of 35.4 mm. Each isosceles trapezoid has an upper base length of 95 mm, a lower base length of 145 mm, and two hypotenuses lengths of 35.4 mm. (Refer to...) Figure 3 In this embodiment 1, the origami structure 1 is folded inward at 45° along the crease, and the cuboid origami structure is deformed, proving the feasibility of the origami structure 1 of the present invention.

[0038] Example 2: Combination Figure 1 The structural diagram and Figure 4 The filter feeder structure diagram in the figure further describes Embodiment 2. The filter feeder structure of Embodiment 2 in this invention is similar to... Figure 1 The same. The filter feed line 5 includes a hairpin microstrip line 51 and a coupling microstrip line 52, located in the right-hand region of the upper surface of the second dielectric substrate 62. The total length of the hairpin microstrip line 51 is:

[0039]

[0040] Where l1 is the total length of the hairpin microstrip line, f n1 This is the zero-point frequency of low-frequency radiation. In Example 2, the hairpin-type microstrip line 51 has a total length of 46.6 mm and a width of 2 mm.

[0041] In this embodiment of the invention, the hairpin-type microstrip line 4 has a triangular chamfer at the left end of each of the two microstrip lines placed horizontally to improve frequency selectivity, and a triangular chamfer at the top and bottom ends of the microstrip line placed vertically.

[0042] The length of the coupled microstrip line 52 is:

[0043]

[0044] Where l2 is the length of the coupled microstrip line, f n2 The frequency is the zero-point frequency of high-frequency radiation. In Example 2, the coupling microstrip line 52 is 40 mm long and 2 mm wide, and its right end is 1.2 mm away from the vertical microstrip line of the hairpin-shaped microstrip line 51.

[0045] Example 3: Combination Figure 1 The structural diagram in the figure further describes Example 3. (Refer to...) Figure 5 Metal stub 4 and filter feed line 5 are simultaneously connected to coaxial feed line 8, and are adhered to the right side of the upper surface of the second dielectric substrate 62. When the pattern-reconfigurable filter antenna is folded inward 90° along the crease of the origami structure, filter feed line 5 couples and feeds the radiating patch 2 located above the first dielectric substrate 61, and the antenna operates in directional radiation mode while also possessing filtering characteristics. In embodiment 3, metal stub 4 has a length of 47 mm and a width of 15 mm.

[0046] Example 4: Combination Figure 1 The structural diagram in the figure further describes Embodiment 4. The antenna structure of Embodiment 4 in this invention is similar to... Figure 1 Same. (Refer to...) Figure 5 In Example 4, the pattern-reconfigurable filter antenna is in its deployed operating state. The metal stub 4 located on the right side of the lower surface of the origami structure 1 directly feeds the monopole radiating patch 3 located on the right side of the origami structure 1. The radiating patch 2 is far from the filter feed line 4 and is in an inactive state.

[0047] Example 5: Combination Figure 1 The structural diagram in Figure 2The present invention provides a front view of one of the four sides of the origami structure and Embodiment 1, and further describes Embodiment 5. Referring to Embodiment 1, a schematic diagram is shown demonstrating a cuboid origami structure 1 folded inward at 45° along the creases of the origami structure. (Refer to...) Figure 7 When the pattern-reconfigurable filter antenna is folded inward by 90° along the crease of the origami structure 1, the schematic diagram of Embodiment 5 is obtained. At this time, the filter feed line 5 located on the right side above the second dielectric substrate 62 feeds the radiating patch 2 located on the right side above the first dielectric substrate 61 through coupling feeding, and the antenna operates in directional radiation mode. The monopole radiating patch 3 is folded inward by 90° along the crease of the right-side origami structure 1, and the monopole radiating patch 3 is in a non-operating state.

[0048] The technical effects of this invention will be further explained below with reference to simulation experiments:

[0049] 1. Experimental conditions and contents:

[0050] The S11 performance and radiation pattern of Embodiment 4 of the present invention were simulated using the three-dimensional full-wave electromagnetic field simulation software ANSYS HFSS18.0. The results are as follows: Figure 8 and Figure 9 As shown.

[0051] 2. Simulation Result Analysis of Example 4:

[0052] Figure 8 The image shows the S11 performance simulation of Example 4 with the proposed antenna in its deployed state. The antenna's operating range (S11 < -10dB) is 0.64GHz-0.72GHz, and its bandwidth is 11.8%. Figure 9 Example 4 shows the proposed antenna in its deployed state in the xoz plane at 0.7 GHz. The radiation pattern in the xoy plane (θ = 50°) shows that the antenna is in omnidirectional radiation mode with a maximum gain of over 2 dBi. The maximum radiation direction of the antenna in the xoz plane is θ = 50°. It has good omnidirectional radiation characteristics in the xoy plane and the non-circularity is less than 1 dB.

[0053] The S11 and Realized gain performance and radiation pattern of Embodiment 5 of the present invention were simulated using the three-dimensional full-wave electromagnetic field simulation software ANSYS HFSS18.0. The results are as follows: Figure 10 and Figure 11 As shown.

[0054] 3. Simulation Result Analysis of Example 5:

[0055] Figure 10The simulation graphs show the S11 and Realized gain performance of Example 5 with the proposed antenna in its folded state. The antenna's operating frequency (S11 < -10dB) ranges from 2.43GHz to 2.47GHz, with a relative bandwidth of 1.6%. The Realized gain curves show that the proposed antenna exhibits filtering characteristics in its folded state, with two filtering zeros at 2.18GHz and 2.94GHz, effectively suppressing out-of-band interference. Within the passband of the Realized gain curve, the antenna operates normally, with an average Realized gain exceeding 5dBi. Figure 11 The simulation diagram of the radiation direction of the proposed antenna embodiment 5 at 2.45 GHz shows that the proposed antenna can maintain good directional radiation performance in the passband, and the radiation patterns of the E-plane and H-plane are stable.

[0056] Therefore, the pattern reconfigurable filter antenna based on origami structure proposed in this invention solves the problems of additional insertion loss caused by using PIN diodes to switch radiation modes, increased manufacturing cost and complexity due to the introduction of bias circuits, and inability to suppress out-of-band interference signals.

Claims

1. A direction pattern reconfigurable filtering antenna based on origami structure, comprising an antenna radiation structure arranged on an antenna ground plane (7), characterized in that: The antenna radiating structure includes a cuboid origami structure (1), a radiating patch (2), a monopole radiating patch (3), a metal stub (4), a filter feed line (5), a first dielectric substrate (61), a second dielectric substrate (62), and a coaxial feed line (8); the origami structure (1) includes a first dielectric substrate (61) placed on the left side of its upper surface and a second dielectric substrate (62) placed on the left side of its lower surface, a monopole radiating patch (3) pasted on its right surface, and a metal stub (4) pasted on the right side of its lower surface; the radiating patch (2) is pasted on the right side of the upper surface of the first dielectric substrate (61); the filter feed line (5) includes a hairpin-shaped micro The antenna has a strip line (51) and a coupled microstrip line (52). When the pattern reconfigurable filter antenna is folded inward at 90° along the crease of the origami structure, the antenna structure is compressed downward and is in a fully folded state. The filter feed line (5) couples and feeds the radiating patch (2) located above the first dielectric substrate (61), and the antenna works in directional radiation mode, while the monopole radiating patch is in a non-working state. When the pattern reconfigurable filter antenna is in the unfolded working state, the metal branch (4) located on the right side of the lower surface of the origami structure (1) directly feeds the monopole radiating patch (3) located on the right side of the origami structure (1), and the radiating patch (2) is in a non-working state.

2. The reconfigurable directional pattern filter antenna based on origami structure according to claim 1, wherein, The origami structure (1) is made of any one of paper, flexible material or plastic material.

3. The paper-folding structure based directional pattern reconfigurable filtering antenna according to claim 1, wherein, The origami structure (1) is a cuboid consisting of four sides and two top and bottom surfaces. Each side is composed of four isosceles right triangles and four isosceles trapezoids. The right-angled sides of the isosceles right triangles are connected to the hypotenuses of the isosceles trapezoids, and the connected sides form creases.

4. The paper-folding structure based directional diagram reconfigurable filtering antenna of claim 1, wherein, The radiation patch (2) is a square made of metallic material and is pasted on the right side of the upper surface of the first dielectric substrate (61). The side length of the square is: ； wherein is the side length of the square, is the speed of light in free space, is the center frequency of the directional radiation pattern, is the effective dielectric constant.

5. The reconfigurable filter antenna based on origami structure directional pattern of claim 4, wherein, The monopole radiation patch (3) is a rectangular piece of metal and is pasted on the center area of ​​the right surface of the origami structure (1). The long side of the rectangle is: ； in, The longer side of the rectangle. This is the center frequency of the omnidirectional radiation mode.

6. The paper-folding structure based directional diagram reconfigurable filtering antenna of claim 1, wherein, The metal branch (4) is pasted on the right side of the lower surface of the origami structure (1), and the metal branch (4) is connected in series with the monopole radiating patch (3) to feed the monopole radiating patch (3).

7. The paper-folding structure based directional diagram reconfigurable filtering antenna of claim 1, wherein, The filter feed line (5) is made of copper metal and consists of a hairpin microstrip line (51) and a coupling microstrip line (52). It is attached to the right side of the upper surface of the second dielectric substrate (62). The total length of the hairpin microstrip line (51) is: ； wherein, is the total length of the hairpin microstrip line, is the low frequency radiation zero frequency, is the speed of light in free space; The length of the coupled microstrip line (52) is: ； wherein, is the length of the coupled microstrip line, is the high frequency radiation zero frequency.

8. The paper-folding structure based directional diagram reconfigurable filtering antenna of claim 1, wherein, The metal stub (4) and the filter feed line (5) are simultaneously connected to the coaxial feed line (8), and the metal stub (4) and the filter feed line (5) are pasted on the right side of the upper surface of the second dielectric substrate (62).

9. The paper-folding structure based directional diagram reconfigurable filtering antenna of claim 1, wherein, The relative permittivity of the first dielectric substrate (61) and the second dielectric substrate (62) is 3.55.

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