A broadband reconfigurable antenna based on dipole

Abstract

The present invention discloses a broadband directional pattern reconfigurable antenna based on a dipole, belonging to the technical field of microwave antennas. The antenna of the present invention comprises a dielectric substrate, a central patch, four broadband balun feeding structures, four PIN diode switches, a DC bias circuit, four parasitic metal structures, four folded dipoles and a coaxial line; the PIN diode switch is loaded between the central patch and the corresponding broadband balun feeding structure to stimulate the broadband balun feeding structure in different directions, so that the folded dipole under the dielectric substrate participates in the radiation, and the main radiation patch is switched on and off by loading the DC bias control switch, so that the surface current distribution of the antenna can be changed to achieve different beam pointing directions. The directional pattern reconfigurable antenna of the present invention can realize the switching of four different beam pointing directions in the azimuth plane, and has the advantages of wide working frequency band, fast switching speed, stable performance, simple structure, and easy processing.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave antennas, and in particular relates to a broadband directional pattern reconfigurable antenna based on a dipole. Background Art

[0002] Antennas are terminal devices for sending and receiving electromagnetic wave signals in wireless communication systems and are closely related to the performance of communication systems. With the growing demand for human communication, research on antennas has continued to develop and improve. Currently, antenna design is moving towards miniaturization, large capacity, diversified performance and easy integration. The concept of reconfigurable antennas has also emerged.

[0003] Reconfigurable antennas can dynamically change their operating modes according to environmental requirements to meet the various needs of wireless communication systems, such as changing the antenna's operating frequency band, polarization mode, or radiation pattern. This can effectively solve the problem of multiple antennas in the same communication system, and provides a solution for achieving low cost, miniaturization, multi-functions, and reducing electromagnetic compatibility issues between antennas.

[0004] The reconfigurable antenna can dynamically control the radiation pattern of the antenna according to the external environment to selectively receive signals and reduce noise interference. It can also adapt to applications under various transceiver requirements. It has the advantages of increasing radiation coverage, improving communication quality, and enabling beam scanning for point-to-multipoint communications. It has broad application prospects.

[0005] The Chinese invention patent application entitled "A Miniaturized Multi-Beam Reconfigurable Antenna and Planar Phased Array Antenna" and publication number CN114156661A discloses a reconfigurable antenna, which selects the main radiation beam direction by controlling the annular equivalent magnetic flux gap structure set on the metal floor through a PIN diode switch, and then realizes continuous scanning of the two-dimensional spatial beam by adjusting the feeding phase and amplitude of the array, with an operating bandwidth of about 14%. The prior art "A Low-Profileand Stacked Patch Antenna for Pattern-Reconfigurable Applications" discloses a stacked patch antenna that realizes the reconstruction of omnidirectional and directional patterns. Although the bandwidth of the two working modes of the antenna is more than 20%, the stacking structure and the complex feeding network increase the processing difficulty of the structure. The prior art "Pattern-Reconfigurable Yagi-Uda Antenna Based on Liquid Metal" discloses a pattern-reconfigurable Yagi-Uda antenna based on liquid metal, which reconfigures the radiation pattern through the adjustment of liquid metal, but the working bandwidth is less than 5%. In summary, the design of the prior art reconfigurable pattern antenna generally has technical problems such as narrow working bandwidth and complex structure. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a broadband directional pattern reconfigurable antenna based on a dipole.

[0007] The technical problem proposed by the present invention is solved in this way:

[0008] A broadband directional pattern reconfigurable antenna based on a dipole has a 90° central rotation symmetric structure, comprising a dielectric substrate 1, a central patch 2, four broadband balun feeding structures 3, four PIN diode switches 4, a DC bias circuit 5, four parasitic metal structures 6, four folded dipoles 7 and a coaxial line;

[0009] The central patch 2, four broadband balun feeding structures 3, four PIN diode switches 4 and a DC bias circuit 5 are located on the upper surface of the dielectric substrate 1;

[0010] The central patch 2 is located at the center of the upper surface of the dielectric substrate 1, and includes a circular patch and four short branches, one end of the short branch is connected to the circular patch, and the other end extends in a direction away from the circular patch, and the short branch is parallel to the edge of the dielectric substrate 1; the broadband balun feeding structure 3 includes a first microstrip line, a second microstrip line and a third microstrip line connected in sequence; the short branch of the central patch 2 is connected to the first microstrip line through a PIN diode switch 4; the positive electrode of the PIN diode switch 4 is connected to the first microstrip line, and the negative electrode is connected to the short branch of the central patch 2; the first microstrip line and the third microstrip line are located on the same side of the second microstrip line and are perpendicular to the short branch of the central patch 2; the second microstrip line is parallel to the short branch of the central patch 2; the length of the first microstrip line is greater than that of the third microstrip line; the voltage source of the DC bias circuit 5 is connected to the first microstrip line, and the ground end is connected to the short branch of the central patch 2;

[0011] Four folded dipoles 7 and four parasitic metal structures 6 are located on the lower surface of the dielectric substrate 1;

[0012] The folded dipole 7 includes two symmetrical inwardly folded antenna arms, each of which includes three sections connected in sequence; the first section of the antenna arm extends from the center of the lower surface of the dielectric substrate 1 to the edge, and is parallel to the edge of the dielectric substrate 1; the second section of the antenna arm is perpendicular to the first section of the antenna arm, and extends from the end of the first section of the antenna arm to a direction away from the center of the lower surface of the dielectric substrate 1; the third section of the antenna arm forms an angle of 45° with the second section of the antenna arm, and extends from the end of the second section of the antenna arm to the center of the lower surface of the dielectric substrate 1; the ends of the first sections of the antenna arms of two adjacent antenna arms close to the center of the lower surface of the dielectric substrate 1 are interconnected;

[0013] Four parasitic metal structures 7 are printed on the four corners of the lower surface of the dielectric substrate 1, including three sections of parasitic patches connected in sequence; the first section of the parasitic patch and the third section of the parasitic patch are parallel to the adjacent sides of the dielectric substrate 1 respectively, and the second section of the parasitic patch forms an angle of 45° with the side of the dielectric substrate 1;

[0014] The coaxial line is located at the center of the lower surface of the dielectric substrate 1 , the outer conductor is connected to the folded dipole 7 , and the inner conductor passes through the dielectric substrate 3 and is connected to the central patch 2 .

[0015] Furthermore, the dielectric substrate 1 is made of Rogers-4350b, with a relative dielectric constant of 3.66, a loss tangent value of 0.0037, and a thickness of 0.76 mm.

[0016] Furthermore, the PIN diode switch 4 is of model MACOMs MA4AGBLP912. When the diode is forward-conducting, it is equivalent to a 4Ω resistor connected in series with a 0.7nH inductor. When the diode is reverse-cutoff, it is equivalent to a 3000Ω resistor connected in parallel with a 0.026pFd capacitor and then connected in series with a 0.7nH inductor.

[0017] Furthermore, the line width of the DC bias circuit 5 is 0.3 mm, and a 120 nH choke inductor is embedded in the DC bias circuit 5 to prevent high-frequency coupling current.

[0018] Furthermore, the characteristic impedance of the coaxial line is 50Ω.

[0019] Furthermore, by loading direct current through the direct current bias circuit 5, the on-off control of the PIN diode switch can be realized, thereby feeding the corresponding broadband balun feeding structure 3;

[0020] Furthermore, the working principle of the antenna of the present invention to achieve pattern reconstruction is as follows:

[0021] The PIN diode switch 4 is loaded between the central patch 2 and the corresponding broadband balun feeding structure 3. The central patch 2 is fed by a coaxial line. The DC bias circuit 5 is printed near the PIN diode switch. By loading DC power, the on-off control of the PIN diode switch 4 can be realized, thereby feeding the broadband balun feeding structure 3 in different directions, so that the antenna can switch back and forth between four different beam directions.

[0022] When two adjacent PIN diode switches are turned on and the other PIN diode switches are turned off, the broadband balun feeding structure 3 in the corresponding two directions is stimulated, and the broadband balun feeding structure 3 further stimulates the folded dipole 6 printed on the lower surface 1 of the dielectric substrate. At this time, two groups of folded dipoles participate in radiation, and the other two groups of folded dipoles act as metal grounds to reflect the radiation energy in the direction of the folded dipoles participating in the radiation.

[0023] The beneficial effects of the present invention are:

[0024] The antenna of the present invention operates at 3.5GHz and can realize switching of beam pointing in four directions of 45°, 135°, 225°, and 315° on the azimuth plane, and the radiation range covers a 360° plane; the antenna of the present invention utilizes a broadband balun feeding structure, and enables multiple patches to participate in radiation at the same time, and the impedance matching bandwidth reaches 54%, which is wider than that of the same type of antennas, and has a stable radiation radiation pattern and gain; the antenna of the present invention adopts a folded dipole design, fully utilizes the antenna aperture, has a compact structure, and is smaller in size than the same type of antennas; the antenna of the present invention has a simple structure, is easy to process, and is highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A top view of the antenna of the present invention;

[0026] Figure 2 A bottom view of the antenna of the present invention;

[0027] Figure 3is a cross-sectional view of the antenna of the present invention;

[0028] Figure 4 is a S11 parameter diagram of the antenna in the embodiment working in mode 1;

[0029] Figure 5 is a gain curve diagram of the antenna in the embodiment working in mode 1;

[0030] Figure 6 : is the radiation pattern of the antenna in the embodiment in the azimuth plane at 4 GHz when the antenna operates in mode 1;

[0031] Figure 7 : is the radiation pattern of the antenna in the embodiment in the azimuth plane at 4 GHz when the antenna operates in mode 2;

[0032] Figure 8 : is the radiation pattern of the antenna in the embodiment in the azimuth plane at 4 GHz when the antenna operates in mode 3;

[0033] Fig. 9 Graph 1 is the radiation pattern of the antenna in the embodiment at 4 GHz when operating in mode 4. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] This embodiment provides a dipole-based broadband directional pattern reconfigurable antenna, which has a 90° central rotation symmetric structure, including a dielectric substrate 1, a central patch 2, four broadband balun feeding structures 3, four PIN diode switches 4, a DC bias circuit 5, four parasitic metal structures 6, four folded dipoles 7 and a coaxial line;

[0036] like Figure 1 As shown, the central patch 2, four broadband balun feeding structures 3, four PIN diode switches 4 and a DC bias circuit 5 are located on the upper surface of the dielectric substrate 1;

[0037] The central patch 2 is located at the center of the upper surface of the dielectric substrate 1, including a circular patch and four short branches, one end of the short branch is connected to the circular patch, and the other end extends in the direction away from the circular patch, and the short branch is parallel to the edge of the dielectric substrate 1; the broadband balun feeding structure 3 includes a first microstrip line, a second microstrip line and a third microstrip line connected in sequence; the short branch of the central patch 2 is connected to the first microstrip line through a PIN diode switch 4; the positive electrode of the PIN diode switch 4 is connected to the first microstrip line, and the negative electrode is connected to the short branch of the central patch 2; the first microstrip line and the third microstrip line are located on the same side of the second microstrip line and are perpendicular to the short branch of the central patch 2; the second microstrip line is parallel to the short branch of the central patch 2; the length of the first microstrip line is greater than that of the third microstrip line; the voltage source of the DC bias circuit 5 is connected to the first microstrip line, and the ground end is connected to the short branch of the central patch 2.

[0038] like Figure 2 As shown, four folded dipoles 7 and four parasitic metal structures 6 are located on the lower surface of the dielectric substrate 1;

[0039] The folded dipole 7 includes two symmetrical inwardly folded antenna arms, each of which includes three sections connected in sequence; the first section of the antenna arm extends from the center of the lower surface of the dielectric substrate 1 to the edge, and is parallel to the edge of the dielectric substrate 1; the second section of the antenna arm is perpendicular to the first section of the antenna arm, and extends from the end of the first section of the antenna arm to a direction away from the center of the lower surface of the dielectric substrate 1; the third section of the antenna arm is at an angle of 45° to the second section of the antenna arm, and extends from the end of the second section of the antenna arm to the center of the lower surface of the dielectric substrate 1; the ends of the first sections of the antenna arms of two adjacent antenna arms close to the center of the lower surface of the dielectric substrate 1 are interconnected. The folded dipole 7 can be coupled and excited by a broadband balun feeding structure 3 printed on the upper surface of the dielectric substrate; compared with the existing dipoles, this structure can maximize the use of the antenna aperture and reduce the overall structure volume;

[0040] Four parasitic metal structures 7 are printed on the four corners of the lower surface of the dielectric substrate 1, including three sections of parasitic patches connected in sequence; the first section of the parasitic patch and the third section of the parasitic patch are parallel to the adjacent sides of the dielectric substrate 1, respectively, and the second section of the parasitic patch forms a 45° angle with the side of the dielectric substrate 1. The four parasitic metal structures 7 are used to further widen the impedance bandwidth, act as directors to maintain the directivity of the radiation pattern, and stabilize the gain of the antenna in the entire working frequency band.

[0041] The coaxial line is located at the center of the lower surface of the dielectric substrate 1 , the outer conductor is connected to the folded dipole 7 , and the inner conductor passes through the dielectric substrate 3 and is connected to the central patch 2 .

[0042] In this embodiment, the dielectric substrate 1 is made of Rogers-4350b, with a dielectric constant of 3.66 and a thickness of 0.76 mm.

[0043] In this embodiment, the PIN diode switch 4 is of model MACOMs MA4AGBLP912. When the diode is forward-conducting, it is equivalent to a 4Ω resistor connected in series with a 0.7nH inductor. When the diode is reverse-cutoff, it is equivalent to a 3000Ω resistor connected in parallel with a 0.026pF capacitor and then connected in series with a 0.7nH inductor.

[0044] In this embodiment, the width of the DC bias line is 0.3 mm, and a 120 nH choke inductor is embedded in the DC bias circuit to prevent high-frequency coupling current.

[0045] In this embodiment, the characteristic impedance of the coaxial feeding interface used for feeding is 50Ω.

[0046] The antenna described in this embodiment has a rotationally symmetric structure, which can ensure that other working performances of the antenna remain stable while the directional pattern is reconstructed.

[0047] The working principle of realizing directional pattern reconstruction in this embodiment is as follows:

[0048] The four PIN diode switches 4 are respectively recorded as PIN diode switch 4-1, PIN diode switch 4-2, PIN diode switch 4-3 and PIN diode switch 4-4, which are respectively loaded between the central patch 2 and the corresponding broadband balun feeding structure 3. The central patch 2 is fed by a coaxial line. The DC bias circuit 5 is printed near the PIN diode switch. The on-off control of the switch can be realized by loading DC power, so as to select to feed the broadband balun feeding structure 3 in different directions, so that the antenna can switch back and forth in four different beam directions.

[0049] By turning on two adjacent PIN diode switches and disconnecting other PIN diode switches, the broadband balun feed structure 3 in the corresponding two directions can be stimulated, and the broadband balun feed structure 3 can further stimulate the folded dipole 6 printed on the lower surface 1 of the dielectric substrate. At this time, it is equivalent to two groups of folded dipoles participating in radiation, and the other two groups of folded dipoles can act as metal grounds to reflect the radiation energy to the direction of the folded dipoles participating in radiation, so that the radiation beam has a certain degree of directivity. The capacitance of the PIN diode switch is matched with the broadband balun feed structure 3, and the antenna can operate over a very wide frequency band. The parasitic patches printed at the four corners of the dielectric substrate can generate resonance at high frequencies, further widening the bandwidth, and can also act as a director to maintain the directivity of the radiation pattern and stabilize the gain of the antenna in the entire working frequency band.

[0050] By controlling the on and off of four PIN diode switches, the distribution of current on the antenna surface can be changed, and the switching of beam pointing in four directions of 45°, 135°, 225° and 315° can be realized on the azimuth plane. The radiation range can cover a 360° plane. Since the antenna is a rotationally symmetrical structure, the four working modes have almost the same working parameters except for the change in radiation direction.

[0051] More specifically, in this embodiment, Figure 1 , Figure 2 and Figure 3 The dimensions of the antenna structure shown are given in Table 1:

[0052] Table 1 Structural dimensions of the antenna described in this embodiment

[0053] parameter value parameter value lf1 11.5mm L 45mm lf2 2.9mm w1 2.2mm lf3 3.6mm w2 3.1mm wf 1.2mm w3 7mm l1 16.5mm lp1 13.6mm l2 23mm lp2 8.6mm l3 7.9mm wp1 2.1mm H 0.76mm

[0054] The antenna described in this embodiment is modeled and simulated using electromagnetic full-wave simulation software CST Studio Suite 2020, and it is defined that when the PIN diode switches 4-1 and 4-2 are turned on, the antenna works in mode 1, when the PIN diode switches 4-2 and 4-3 are turned on, the antenna works in mode 2, when the PIN diode switches 4-3 and 4-4 are turned on, the antenna works in mode 3, and when the PIN diode switches 4-4 and 4-1 are turned on, the antenna works in mode 4;

[0055] Figure 4 This is the S11 parameter diagram of the antenna in this embodiment working in mode 1. The simulation bandwidth of the reconstructed antenna reflection coefficient less than -10dB is 2.96GHz-5.15GHz, with 4.05GHz as the center frequency, and its relative working bandwidth is 54%, achieving good broadband performance. Due to the symmetry of the structure, the impedance bandwidth of the antenna overlaps in all working modes.

[0056] Figure 5 is the gain curve of the antenna in this embodiment working in mode 1, Figure 5 It can be seen that the gain fluctuation range of the antenna in the entire working frequency band is 2-4.2dBi, and the gain performance is stable. Due to the symmetry of the structure, the gain of the antenna in other working modes is almost the same as that in mode 1.

[0057] Figure 6 This is the radiation pattern of the antenna in this embodiment in the azimuth plane at 4 GHz when it works in mode 1. The maximum radiation direction points to θ=45°, the front-to-back ratio is greater than 10 dB, and the beam pointing is stable in the entire working frequency band.

[0058] Figure 7This is the radiation pattern of the antenna described in this embodiment in the azimuth plane at 4 GHz when working in mode 2. The maximum radiation direction points to θ=135°, the front-to-back ratio is greater than 10 dB, and the beam pointing is stable in the entire working frequency band.

[0059] Figure 8 This is the radiation pattern of the antenna described in this embodiment in the azimuth plane at 4 GHz when working in mode 3. The maximum radiation direction points to θ=225°, the front-to-back ratio is greater than 10 dB, and the beam pointing is stable in the entire working frequency band.

[0060] Fig. 9 This is the radiation pattern of the antenna in this embodiment in the azimuth plane at 4 GHz when it works in mode 4. The maximum radiation direction points to θ=315°, the front-to-back ratio is greater than 10 dB, and the beam pointing is stable in the entire working frequency band.

[0061] According to the above simulation results, it can be seen that the broadband directional pattern reconfigurable antenna in this embodiment can realize the switching of four beam directions within 2.96GHz-5.15GHz, the working bandwidth reaches 54%, and has stable working performance.

[0062] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A broadband directional pattern reconfigurable antenna based on a dipole, characterized in that: The structure is 90° central rotationally symmetrical, comprising a dielectric substrate (1), a central patch (2), four broadband balun feeding structures (3), four PIN diode switches (4), a DC bias circuit (5), four parasitic metal structures (6), four folded dipoles (7) and a coaxial line; The central patch (2), four broadband balun feeding structures (3), four PIN diode switches (4) and a DC bias circuit (5) are located on the upper surface of the dielectric substrate (1); The central patch (2) is located at the center of the upper surface of the dielectric substrate (1), and comprises a circular patch and four short branches, one end of the short branch is connected to the circular patch, and the other end extends in a direction away from the circular patch, and the short branch is parallel to the edge of the dielectric substrate (1); the broadband balun feeding structure (3) comprises a first microstrip line, a second microstrip line and a third microstrip line connected in sequence; the short branch of the central patch (2) is connected to the first microstrip line through a PIN diode switch (4); the positive electrode of the PIN diode switch (4) is connected to the first microstrip line, and the negative electrode is connected to the short branch of the central patch (2); the first microstrip line and the third microstrip line are located on the same side of the second microstrip line and are perpendicular to the short branch of the central patch (2); The second microstrip line is parallel to the short branch of the central patch (2); the length of the first microstrip line is greater than that of the third microstrip line; the voltage source of the DC bias circuit (5) is connected to the first microstrip line, and the ground end is connected to the short branch of the central patch (2); Four folded dipoles (7) and four parasitic metal structures (6) are located on the lower surface of the dielectric substrate (1); The folded dipole (7) comprises two symmetrical inwardly folded antenna arms, each antenna arm comprising three sections connected in sequence; the first section of the antenna arm extends from the center of the lower surface of the dielectric substrate (1) to the edge, and is parallel to the edge of the dielectric substrate (1); the second section of the antenna arm is perpendicular to the first section of the antenna arm, and extends from the end of the first section of the antenna arm in a direction away from the center of the lower surface of the dielectric substrate (1); the third section of the antenna arm forms an angle of 45° with the second section of the antenna arm, and extends from the end of the second section of the antenna arm in a direction toward the center of the lower surface of the dielectric substrate (1); the ends of the first sections of the antenna arms of two adjacent antenna arms close to the center of the lower surface of the dielectric substrate (1) are interconnected; Four parasitic metal structures (6) are printed on the four corners of the lower surface of the dielectric substrate (1), including three sections of parasitic patches connected in sequence; the first section of the parasitic patch and the third section of the parasitic patch are respectively parallel to the adjacent edges of the dielectric substrate (1), and the second section of the parasitic patch forms an angle of 45° with the edge of the dielectric substrate (1); The coaxial line is located at the center of the lower surface of the dielectric substrate (1), the outer conductor is connected to the folded dipole (7), and the inner conductor passes through the dielectric substrate (1) and is connected to the center patch (2); The working principle of antenna pattern reconstruction is as follows: A PIN diode switch (4) is loaded between the central patch (2) and the corresponding broadband balun feeding structure (3), the central patch (2) is fed by a coaxial line, a DC bias circuit (5) is printed near the PIN diode switch (4), and the on-off control of the PIN diode switch (4) is realized by loading DC power, thereby feeding the broadband balun feeding structure (3) in different directions, so that the antenna switches back and forth among four different beam directions; When two adjacent PIN diode switches (4) are turned on and the other PIN diode switches (4) are turned off, the broadband balun feeding structures (3) in the corresponding two directions are excited, and the broadband balun feeding structures (3) further excite the folded dipoles (7) printed on the lower surface of the dielectric substrate (1). At this time, two groups of folded dipoles (7) participate in radiation, and the other two groups of folded dipoles (7) act as metal grounds to reflect the radiation energy in the direction of the folded dipoles (7) participating in the radiation.

2. The dipole-based broadband reconfigurable directional pattern antenna according to claim 1, characterized in that: The dielectric substrate (1) is made of Rogers-4350b, with a relative dielectric constant of 3.66, a loss tangent value of 0.0037, and a thickness of 0.76 mm.

3. The dipole-based broadband reconfigurable directional pattern antenna according to claim 1, characterized in that: The PIN diode switch (4) is of model MACOMs MA4AGBLP912. When the diode is forward conducting, it is equivalent to a 4Ω resistor connected in series with a 0.7nH inductor. When the diode is reverse conducting, it is equivalent to a 3000Ω resistor connected in parallel with a 0.026pFd capacitor and then connected in series with a 0.7nH inductor.

4. The dipole-based broadband reconfigurable directional pattern antenna according to claim 1, characterized in that: The line width of the DC bias circuit (5) is 0.3 mm, and a 120 nH choke inductor is embedded in the DC bias circuit (5) to prevent high-frequency coupling current.

5. The dipole-based broadband reconfigurable directional pattern antenna according to claim 1, characterized in that: The characteristic impedance of the coaxial cable is 50Ω.

6. The dipole-based broadband reconfigurable directional pattern antenna according to claim 1, characterized in that: The on-off control of the PIN diode switch (4) is achieved by loading direct current through a direct current bias circuit (5), thereby feeding the corresponding broadband balun feeding structure (3).

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