Four-blade fan-shaped reconfigurable antenna based on characteristic mode theory

Abstract

The present invention discloses a four-blade fan-shaped directional pattern reconfigurable antenna designed based on characteristic mode theory, which relates to the technical field of reconfigurable antennas. The antenna comprises a dielectric disk, a central circular patch, four peripheral arc-shaped patches, four PIN diodes, a coaxial line and a metal floor. The advantage of the present invention is that by adopting a central coaxial line feeding method and loading PIN diodes between the gaps, flexible switching between omnidirectional and directional radiation modes under single-port feeding conditions is achieved. Simulation verification shows that the antenna can achieve directional radiation at four specific angles of 45°, 135°, 225° and 315° in the azimuth plane within the 3.3-3.4GHz frequency band, while having omnidirectional radiation capability and complete coverage of the entire azimuth plane. Such diverse radiation characteristics can flexibly adapt to the antenna performance requirements of different application scenarios, and are particularly suitable for wireless communications and 5G networks in the microwave frequency band. Compared with traditional design methods, the design approach based on characteristic mode theory provides a new perspective for antenna designers.

Description

Technical Field

[0001] The present invention relates to the technical field of reconfigurable antennas, in particular to a four-blade fan-shaped directional pattern reconfigurable antenna designed based on characteristic mode theory. Background Art

[0002] In mobile communication systems, antennas, as signal transmitters and receivers, play an indispensable role. Traditional antenna design often focuses on specific applications or performance metrics. Once their geometry and physical characteristics are determined, they are difficult to adjust, limiting their performance to specific scenarios. This design approach has shown limitations in today's diverse application environments.

[0003] In this context, the concept of reconfigurable antennas has emerged. These antennas aim to meet diverse communication needs by modifying their physical parameters, thereby reducing the number of antennas required. Reconfigurable antennas can be categorized by function as frequency reconfigurable antennas (including those that achieve broadband and multi-band operation), pattern reconfigurable antennas, polarization reconfigurable antennas, and hybrid reconfigurable antennas. Reconfigurable antennas aim to adapt to application scenarios and requirements by adjusting certain antenna radiation characteristics.

[0004] Analytical and numerical methods are two commonly used approaches in traditional antenna design. However, they struggle to intuitively explain the impact of various physical parameters on electromagnetic properties, and lack a clear physical explanation. For antenna designers, attempts without clear guidance waste considerable time and effort, and are more likely to fail to achieve the desired results. Characteristic mode theory provides a physical explanation for the radiation principle of antennas. It decomposes the surface current of an antenna into a series of mutually orthogonal characteristic currents, which are determined solely by the antenna's geometry and material properties and are independent of external excitation sources. Specifically, it can use electromagnetic simulation software to understand the characteristic modes of the designed antenna and analyze its radiation at specific frequencies. This helps designers adjust and optimize the antenna theoretically without having to rely on parameter sweeps, significantly reducing design time and improving efficiency, playing a significant role in antenna design.

[0005] Therefore, how to use the characteristic mode theory to design a reconfigurable antenna so that it can switch between omnidirectional radiation and directional radiation has become a key research direction. To this end, we propose a four-blade fan-shaped reconfigurable antenna based on the characteristic mode theory. Summary of the Invention

[0006] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0007] The present invention adopts the following technical solution to solve the above technical problems: providing a four-blade fan-shaped directional pattern reconfigurable antenna designed based on characteristic mode theory, including a dielectric disk, a central circular patch, four peripheral arc-shaped patches, four PIN diodes, a coaxial line and a metal floor.

[0008] Preferably, the dielectric disk is an insulating low-loss dielectric substrate, the central circular patch is arranged at the center of the upper surface of the dielectric disk, the four outer arc-shaped patches are evenly distributed in a fan shape outside the central circular patch, and a gap is formed between the four outer arc-shaped patches and the central circular patch, the four PIN diodes are respectively loaded in the gaps between the four outer arc-shaped patches and the central circular patch, and the metal floor is arranged on the lower surface of the dielectric disk.

[0009] Preferably, the geometric centers of the dielectric disk, the central circular patch, the peripheral arc-shaped patch and the metal floor coincide with each other to form a centrally symmetrical structure.

[0010] Preferably, the inner core of the coaxial line is connected to the central circular patch, and the outer shell of the coaxial line is connected to the metal floor, so as to realize feeding of the antenna.

[0011] Preferably, the four PIN diodes can be controlled in combination to switch the antenna between omnidirectional radiation and directional radiation in multiple azimuth planes.

[0012] Preferably, the angles of the multiple azimuth planes are 45°, 135°, 225° and 315°.

[0013] Preferably, the dielectric constant of the dielectric disc is 2.94, the loss tangent is 0.0009, the radius is 50 mm, and the thickness is 3 mm; the radius of the central circular patch is 8 mm, the radius of the outer arc patch is 31.5 mm, the central angle is 60°, and the gap width is 0.6 mm.

[0014] Preferably, the PIN diode is of model NSR201MXTG5, which is equivalent to a 1.5Ω resistor and a 0.45nH inductor in series when turned on, and is equivalent to a 0.15pF capacitor when turned off.

[0015] Compared with the existing technology, the present invention provides a four-blade fan-shaped directional pattern reconfigurable antenna designed based on the characteristic mode theory, which has the following beneficial effects: by adopting a central coaxial line feeding method and loading a PIN diode between the gaps, flexible switching between omnidirectional and directional radiation modes under single-port feeding conditions is achieved. After simulation verification, this antenna can achieve directional radiation at four specific angles of 45°, 135°, 225°, and 315° in the azimuth plane within the 3.3-3.4GHz frequency band, and at the same time has omnidirectional radiation capability, completely covering the entire azimuth plane. This diversified radiation characteristic can flexibly adapt to the antenna performance requirements of different application scenarios, and is particularly suitable for wireless communications and 5G networks in the microwave frequency band. Compared with traditional design methods, the design idea based on the characteristic mode theory provides antenna designers with a new perspective, which is clearer and simpler, and significantly improves the efficiency of antenna design. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 3D schematic diagram of the antenna structure with reconfigurable directivity pattern based on characteristic mode theory of the present invention;

[0017] Figure 2 A top view of the antenna structure with reconfigurable directivity pattern based on characteristic mode theory of the present invention;

[0018] Figure 3 The mode significance of the first four characteristic modes of the unloaded PIN diode and the fed PIN diode of the present invention;

[0019] Figure 4 The characteristic current and radiation pattern of the first four characteristic modes of the unloaded PIN diode and the feeding state of the present invention;

[0020] Figure 5 is the S parameter of State 1-5 of the present invention;

[0021] Figure 6 is the maximum gain of State 1-5 of the present invention;

[0022] Figure 7 3D radiation pattern of State 1-5 of the present invention;

[0023] Figure 8 State 1-4 of the present invention is in the azimuth plane 2D radiation pattern of

[0024] Figure 9 State 5 of the present invention is in the elevation plane and 2D radiation pattern when .

[0025] In the figure: 1. Dielectric disk; 2. Central circular patch; 3. Peripheral arc-shaped patch; 4. PIN diode; 5. Coaxial line; 6. Metal floor. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] See also Figure 1-9 The four-blade fan-shaped reconfigurable antenna designed based on the characteristic mode theory includes a dielectric disk 1, a central circular patch 2, four peripheral arc-shaped patches 3, four PIN diodes 4, a coaxial line 5 and a metal floor 6. The dielectric disk 1 has a dielectric constant of 2.94, a loss tangent of 0.0009, a radius of 50 mm, and a thickness of 3 mm. The radius of the central circular patch 2 is 8 mm, the radius of the peripheral arc-shaped patch 3 is 31.5 mm, the central angle is 60°, and the gap width is 0.6 mm. The model of the PIN diode 4 is NSR201MXTG5. When it is turned on, it is equivalent to a 1.5Ω resistor and a 0.45nH inductor in series. When it is turned off, it is equivalent to a 0.15pF capacitor.

[0028] In this embodiment, the dielectric disk 1 is an insulating low-loss dielectric substrate. The central circular patch 2 is located at the center of the upper surface of the dielectric disk 1. Four peripheral arcuate patches 3 are evenly distributed in a fan shape outside the central circular patch 2, forming gaps between the central circular patch 2. Four PIN diodes 4 are respectively loaded in the gaps between the four peripheral arcuate patches 3 and the central circular patch 2. A metal floor 6 is provided on the lower surface of the dielectric disk 1.

[0029] Specifically, the PIN diodes 4 loaded in the gaps between the central circular patch 2 and the four peripheral arc-shaped patches 3 are named PIN1-4 respectively.

[0030] In this embodiment, the geometric centers of the dielectric disk 1 , the central circular patch 2 , the peripheral arc-shaped patch 3 and the metal floor 6 coincide with each other, forming a centrosymmetrical structure.

[0031] In this embodiment, the inner core of the coaxial line 5 is connected to the central circular patch 2 , and the outer shell of the coaxial line 5 is connected to the metal floor 6 , so as to realize power feeding to the antenna.

[0032] Specifically, the characteristic mode analysis is performed on the structure without the PIN diode 4 and when it is fed, and the mode significance of the first four characteristic modes is obtained (such as Figure 3 as shown) and the characteristic current and radiation pattern of the characteristic mode (as shown Figure 4 As shown in the figure, more specifically, Mode 1 and Mode 2 are a set of orthogonal degenerate modes, showing directional radiation with a resonant frequency of 3.47 GHz. Mode 3 and Mode 4 respectively produce beams in four directions, and Mode 4 exhibits good omnidirectional radiation with a resonant frequency of 3.68 GHz.

[0033] In this embodiment, the four PIN diodes 4 can control the on-off combination to switch the antenna between omnidirectional radiation and directional radiation in multiple azimuth planes, and the angles of the multiple azimuth planes are 45°, 135°, 225° and 315°.

[0034] Specifically, this design attempts to simultaneously excite Mode 1, Mode 2, and Mode 4 using a single feed, and by loading a PIN diode (such as Figure 2 By adjusting different switch combinations of the PIN diodes, five feasible operating states (State 1-5) can be obtained. The specific state configurations are detailed in Table 1. Among them, States 1-4 correspond to directional radiation of 315°, 45°, 135° and 225° in the azimuth plane, respectively, while State 5 presents omnidirectional radiation characteristics.

[0035] Table 1

[0036]

[0037] After testing, the S parameters and maximum gain in five states are as follows Figure 5 、 Figure 6 The results show that the operating frequency bands of omnidirectional radiation and directional radiation basically overlap, both concentrated in 3.3GHz-3.4GHz. When the antenna is set to work at 3.35GHz, its 3D radiation pattern is as follows Figure 7 shown.

[0038] From the test data of State 1-4, it can be seen that the main radiation direction of the antenna can achieve precise deflection at four angles of 45°, 135°, 225° and 315° in the azimuth plane. In addition to the different deflection angles, the radiation beam performance in these four directions is basically the same. In the elevation plane, the main beam direction is pointing to The test results of State5 show that the antenna can achieve 360° uniform radiation in the azimuth plane and exhibit good omnidirectional radiation characteristics.

[0039] More specifically, Figure 8 As shown, it is the azimuth plane at the radiation frequency of 3.35GHz 2D far-field radiation pattern when ; Figure 9The corresponding gain data for States 1-5 is intuitively presented. Analysis shows that when in directional radiation states (States 1-4), all four beams achieve approximately 9.5dB of gain at 3.35GHz. In omnidirectional radiation state (State 5), the gain is reduced to approximately 4.5dB due to the uniform dispersion of the signal in all directions. This gain difference is essentially due to the characteristic differences between directional and omnidirectional radiation. Directional radiation focuses signal energy in a specific direction, significantly enhancing signal strength in that direction and thus improving gain performance. Omnidirectional radiation strives for uniform 360° coverage, but the energy dispersion weakens the signal strength in a specific direction.

[0040] In summary, based on the characteristic mode theory, we analyze the radiation mechanism of the antenna from the physical essence, break the limitations of traditional design, and achieve flexible switching between directional radiation and omnidirectional radiation in the 3.3GHz-3.4GHz frequency band, providing a more efficient and innovative solution for antenna design and performance optimization.

[0041] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0042] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A four-blade fan-shaped reconfigurable antenna designed based on characteristic mode theory, characterized by: The invention comprises a dielectric disk (1), a central circular patch (2), four peripheral arc-shaped patches (3), four PIN diodes (4), a coaxial line (5) and a metal floor (6), wherein the dielectric disk (1) is an insulating low-loss dielectric substrate, the central circular patch (2) is arranged at the center of the upper surface of the dielectric disk (1), the four peripheral arc-shaped patches (3) are evenly distributed in a fan shape outside the central circular patch (2), and gaps are formed between the four peripheral arc-shaped patches (3) and the central circular patch (2), and the four PIN diodes (4) are respectively loaded at the gaps between the four outer arc patches (3) and the central circular patch (2); the metal floor (6) is arranged on the lower surface of the dielectric disk (1); the geometric centers of the dielectric disk (1), the central circular patch (2), the outer arc patches (3) and the metal floor (6) coincide with each other, forming a central symmetrical structure; the inner core of the coaxial line (5) is connected to the central circular patch (2), and the outer shell of the coaxial line (5) is connected to the metal floor (6), so as to realize feeding of the antenna.

2. The four-blade fan-shaped reconfigurable antenna designed based on characteristic mode theory according to claim 1, characterized in that: The four PIN diodes (4) can be controlled in combination to switch the antenna between omnidirectional radiation and directional radiation in multiple azimuth planes.

3. The four-blade fan-shaped reconfigurable antenna based on characteristic mode theory design according to claim 2, characterized in that: The angles of the multiple azimuth planes are 45°, 135°, 225° and 315°.

4. The four-blade fan-shaped reconfigurable antenna designed based on characteristic mode theory according to claim 3, characterized in that: The dielectric constant of the dielectric disk (1) is 2.94, the loss tangent is 0.0009, the radius is 50 mm, and the thickness is 3 mm; the radius of the central circular patch (2) is 8 mm, the radius of the peripheral arc-shaped patch (3) is 31.5 mm, the central angle is 60°, and the gap width is 0.6 mm.

5. The four-blade fan-shaped reconfigurable antenna designed based on characteristic mode theory according to claim 1, characterized in that: The PIN diode (4) is of model NSR201MXTG5, which is equivalent to a 1.5Ω resistor and a 0.45nH inductor in series when turned on, and is equivalent to a 0.15pF capacitor when turned off.

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