Circularly polarized log-periodic antenna based on rotation of radiating dipoles

Abstract

The application discloses a circularly polarized logarithmic-periodic antenna based on rotation of radiating oscillators, and belongs to the technical field of antenna engineering, and aims at solving the problem of how to design a circularly polarized logarithmic-periodic antenna with wide bandwidth, low profile and simple structure. The application forms corresponding circularly polarized characteristics by rotating a plurality of groups of radiating oscillators by a certain angle with parallel assembly lines as the shaft. The antenna only has a plurality of radiating oscillators which change according to the logarithmic-periodic antenna rule, and does not have a main oscillator and a sub-oscillator, so that the structure is simpler and easier to realize. Meanwhile, the circularly polarized effect is formed by rotating the radiating oscillators to a certain phase and the phase difference between the electromagnetic waves of each oscillator and the zero point of the antenna, so that the logarithmic-periodic antenna can obtain good impedance bandwidth and 3dB axial ratio bandwidth in the working frequency band.

Description

Technical Field

[0001] This invention belongs to the field of antenna engineering technology and relates to a circularly polarized log-periodic antenna based on the rotation of a radiating dipole. Background Technology

[0002] Log-periodic antennas are a type of non-frequency-variable ultra-wideband antenna with a self-similar structure. Their electrical performance remains essentially unchanged within a 10:1 or even wider frequency band. Conventional log-periodic antennas are fed by coaxial cables with the feed point located on the short-side dipole side. They have advantages such as low profile, small in-band gain fluctuation, symmetrical radiation pattern, simple structure, and ease of fabrication. Therefore, they are widely used in communication, direction finding, electronic warfare, and other fields.

[0003] However, due to the rapid development of modern wireless communication systems and the increasing complexity of the electromagnetic environment, the system has placed more stringent requirements on antenna polarization. Currently, antenna polarization can be divided into three categories: circular polarization, elliptical polarization, and linear polarization. Circularly polarized antennas have better performance than linearly and elliptical polarized antennas. For example, they can suppress multipath fading, can interconnect with any linearly polarized antenna, and can receive or radiate electromagnetic waves of arbitrary polarization. Therefore, they are widely used in positioning, communication, and navigation fields.

[0004] Common circular polarization designs for log-periodic antennas often employ a dual-main-rod structure (corresponding to dual output ports). This typically uses a bridge circuit to convert one signal into two signals with a 90° phase difference, which are then connected to the antenna's dual ports to achieve circular polarization. This approach is complex and bulky, inconvenient to use and operate, and increases manufacturing and operating costs. While some designs utilize phase shifting techniques that eliminate the need for a 90° bridge, they still employ a dual-main-rod structure, resulting in an overall complex and bulky design.

[0005] In the prior art, Chinese invention patent application document "A Circularly Polarized Log-Periodic Antenna" with publication number CN116565517A and publication date August 8, 2023, provides a circularly polarized log-periodic antenna structure. This structure is equivalent to combining two sets of radiating dipoles that change according to a logarithmic periodic law in a perpendicularly intersecting form. The corresponding main and sub-dipole groups have similar lengths, and the perpendicular relationship between the main dipole and the corresponding sub-dipole and the phase difference between the electromagnetic waves radiated to the antenna null point respectively form circular polarization.

[0006] Chinese invention patent application document CN107579338A, published on January 12, 2018, entitled "A Broadband Circularly Polarized Log-Periodic Antenna", provides a broadband circularly polarized log-periodic antenna structure. This structure also adopts a scheme of vertical main and sub-element, but the length variation of its sub-element does not conform to the law of log-periodic antenna. The circular polarization effect is formed by simple mode splitting between adjacent main and sub-element.

[0007] Both of the above structures suffer from problems such as complex and bulky overall structure, difficulty in processing, and complicated operation. Summary of the Invention

[0008] The technical solution of this invention is used to solve the problem of how to design a log-periodic circularly polarized antenna with wide bandwidth, low profile, and simple structure.

[0009] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0010] A circularly polarized log-periodic antenna based on radiating dipole rotation includes: two first radiating dipoles (1), two second radiating dipoles (2), two third radiating dipoles (3), and two parallel convergent lines (4); the two parallel convergent lines (4) are arranged horizontally and parallelly along the y-axis, the two first radiating dipoles (1) are respectively connected to the left ends of the upper and lower parallel convergent lines (4), the axes of the length directions of the two first radiating dipoles (1) are parallel to each other, and the angle between the axes of the length directions of the two first radiating dipoles (1) and the z-axis is 66°; the two second radiating dipoles (2) are respectively connected to the upper and lower parallel convergent lines (4). The two second radiating oscillators (2) are located between the upper and lower parallel convergence lines (4). The axes of the two second radiating oscillators (2) are parallel to each other, and the angle between the axes of the two second radiating oscillators (2) and the z-axis is 30°. The two third radiating oscillators (3) are connected between the upper and lower parallel convergence lines (4). The axes of the two third radiating oscillators (3) are parallel to each other, and the angle between the axes of the two third radiating oscillators (3) and the z-axis is 90°. The length ratio of the first radiating oscillator (1), the second radiating oscillator (2), and the third radiating oscillator (3) is 1:K:K. 2 The ratio of the horizontal spacing between the first radiating oscillator (1), the second radiating oscillator (2), and the third radiating oscillator (3) is 1:K.

[0011] Furthermore, the parallel convergence line (4) is fed at one end near the third radiating element. The cross-feeding of the logarithmic periodic antenna is achieved through the structure of the parallel convergence line (4). The electromagnetic wave energy input from the feeding point is transmitted from the third radiating element end to the first radiating element end along the parallel convergence line (4). During the transmission process, each radiating element is excited in turn to form end-to-end radiation. The maximum radiation direction is from the first radiating element to the third radiating element. During the electromagnetic wave radiation process, there is a phase difference between the electromagnetic waves from the second radiating element (2) and the third radiating element (3) to the antenna null point. At the same time, when the electromagnetic wave propagates from the third radiating element end along the parallel convergence line (4) to each group of radiating elements, the radiating elements are excited and radiate along the air. The radiating elements form the phase of the electromagnetic wave radiation in space by rotating the angle. When the generated electromagnetic wave phases combine to form a phase difference of 90°, the circular polarization characteristic of the antenna is realized.

[0012] Furthermore, the first radiating oscillator (1), the second radiating oscillator (2), the third radiating oscillator (3), and the parallel convergence line (4) are all pre-formed metal columns.

[0013] Preferably, the preformed metal column is made of copper.

[0014] Preferably, the radius of the preformed metal column is 3 mm.

[0015] Preferably, the value of K is in the range of 0.8 to 0.95.

[0016] Preferably, the length of the first radiating oscillator (1) is 100 mm, the length of the second radiating oscillator (2) is 85 mm, the length of the third radiating oscillator (3) is 72.25 mm, and the length of the parallel convergence line (4) is 104.5 mm.

[0017] Preferably, the horizontal axis of each of the parallel assembly lines (4) is 3.8 mm away from the horizontal center symmetry line of the antenna.

[0018] The advantages of this invention are:

[0019] The circularly polarized log-periodic antenna structure proposed in this invention, based on the rotation of radiating dipoles, aims to achieve a simpler and more compact circularly polarized log-periodic antenna. Leveraging the wide bandwidth and low profile advantages of the self-similar structure of traditional log-periodic antennas, this invention achieves circular polarization characteristics by rotating several sets of radiating dipoles at a certain angle around a parallel convergent line. This allows the log-periodic antenna to obtain good impedance bandwidth and 3dB axial ratio bandwidth in the operating frequency band, while being simpler and easier to implement compared to current circularly polarized log-periodic antenna structures. Attached Figure Description

[0020] Figure 1This is a three-dimensional structural schematic diagram of a circularly polarized log-periodic antenna based on the rotation of a radiating oscillator according to Embodiment 1 of the present invention.

[0021] Figure 2 This is a three-dimensional front view of the circularly polarized log-periodic antenna based on the rotation of a radiating oscillator according to Embodiment 1 of the present invention.

[0022] Figure 3 This is a top view of the three-dimensional structure of a circularly polarized log-periodic antenna based on the rotation of a radiating oscillator according to Embodiment 1 of the present invention.

[0023] Figure 4 This is a three-dimensional structural side view of a circularly polarized log-periodic antenna based on radiating oscillator rotation according to Embodiment 1 of the present invention.

[0024] Figure 5 This is a graph of the S11 parameters of a circularly polarized log-periodic antenna based on the rotation of a radiating oscillator according to Embodiment 1 of the present invention.

[0025] Figure 6 The axial ratio curve of the circularly polarized log-periodic antenna based on the rotation of the radiating dipole is shown in Embodiment 1 of the present invention.

[0026] Figure 7 This is a 1.25GHz circularly polarized log-periodic antenna based on radiating dipole rotation, as described in Embodiment 1 of the present invention. Radiation pattern;

[0027] Figure 8 This is a 1.25GHz circularly polarized log-periodic antenna based on radiating dipole rotation, as described in Embodiment 1 of the present invention. Radiation pattern;

[0028] Figure 9 This is a 1.3GHz circularly polarized log-periodic antenna based on radiating dipole rotation, as described in Embodiment 1 of the present invention. Radiation pattern;

[0029] Figure 10 This is a 1.3GHz circularly polarized log-periodic antenna based on radiating dipole rotation, as described in Embodiment 1 of the present invention. Radiation pattern;

[0030] Figure 11 This is a 1.4GHz circularly polarized log-periodic antenna based on radiating dipole rotation, as described in Embodiment 1 of the present invention. Radiation pattern;

[0031] Figure 12 This is a 1.4GHz circularly polarized log-periodic antenna based on radiating dipole rotation, as described in Embodiment 1 of the present invention. Radiation pattern. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0034] Example 1

[0035] like Figures 1 to 4 As shown, the circularly polarized log-periodic antenna based on radiating dipole rotation according to an embodiment of the present invention includes: two first radiating dipoles (1), two second radiating dipoles (2), two third radiating dipoles (3), and two parallel convergent lines (4); the first radiating dipoles (1), the second radiating dipoles (2), the third radiating dipoles (3), and the parallel convergent lines (4) are all preformed metal pillars; preferably, the preformed metal pillars have a radius of 3mm and are made of copper.

[0036] The two parallel convergence lines (4) are set horizontally and parallel along the y-axis. The two first radiating oscillators (1), the two second radiating oscillators (2), and the two third radiating oscillators (3) are arranged alternately from left to right along the y-axis at a certain distance and are connected to the upper and lower parallel convergence lines (4) respectively, as follows:

[0037] Two first radiating oscillators (1) are respectively connected to the left ends of the upper and lower parallel convergence lines (4). The axes of the length direction of the two first radiating oscillators (1) are parallel to each other, and the angle between the axes of the length direction of the two first radiating oscillators (1) and the z-axis is 66°. Two second radiating oscillators (2) are respectively connected to the middle of the upper and lower parallel convergence lines (4). The axes of the length direction of the two second radiating oscillators (2) are parallel to each other, and the angle between the axes of the length direction of the two second radiating oscillators (2) and the z-axis is 30°. Two third radiating oscillators (3) are respectively connected to the middle of the upper and lower parallel convergence lines (4). The axes of the length direction of the two third radiating oscillators (3) are parallel to each other, and the angle between the axes of the length direction of the two third radiating oscillators (3) and the z-axis is 90°.

[0038] The length ratio of the first radiating oscillator (1), the second radiating oscillator (2), and the third radiating oscillator (3) is 1:K:K. 2The horizontal spacing ratio between the first radiating element (1), the second radiating element (2), and the third radiating element (3) is 1:K, and the value of K ranges from 0.8 to 0.95. Preferably, the value of K is 0.85. In this case, the length of the first radiating element (1) is 100mm, the length of the second radiating element (2) is 85mm, the length of the third radiating element (3) is 72.25mm, the length of the parallel convergence line (4) is 104.5mm, and the distance between the horizontal axis of each parallel convergence line (4) and the horizontal center symmetry line of the antenna is 3.8mm.

[0039] The working principle of the antenna is as follows:

[0040] Feeding is provided at one end of the parallel convergence line (4) (near the end of the short radiating element (third radiating element) of the log-periodic antenna). The cross-feeding of the log-periodic antenna is realized through the structure of the parallel convergence line (4). The electromagnetic wave energy input from the feeding point is transmitted along the parallel convergence line (4) from the end of the short radiating element (third radiating element) to the end of the long radiating element (first radiating element). During the transmission process, each radiating element is excited in turn to form end-to-end radiation. The maximum radiation direction is from the long radiating element (first radiating element) to the short radiating element (third radiating element). During the electromagnetic wave radiation process, there is a phase difference between the electromagnetic waves from the second radiating element (2) and the third radiating element (3) to the antenna null point. At the same time, when the electromagnetic wave propagates from the end of the short radiating element (third radiating element) along the parallel convergence line (4) to each group of radiating elements, the radiating elements are excited and radiate along the air. The radiating elements form the phase of the electromagnetic wave radiation in space by rotating a certain angle. When the generated electromagnetic wave phases combine to form a phase difference of 90°, the circular polarization characteristic of the antenna is realized.

[0041] The antenna in this embodiment has only one set of several radiating elements that change in accordance with the logarithmic periodic antenna pattern. There is no distinction between the main and auxiliary elements, making the structure simpler and easier to implement. At the same time, the circular polarization effect is formed by rotating the radiating elements to a certain phase and combining the phase difference between the electromagnetic waves of each element and the antenna null point.

[0042] Figure 5 The image shows the S11 parameter curves of the circularly polarized log-periodic antenna based on radiating dipole rotation in this embodiment after electromagnetic simulation. It can be seen that the reflection coefficient in the 1.19GHz-2.21GHz frequency band... All values ​​were less than -10dB, and the consistency was good.

[0043] Figure 6 The image shows the axial ratio curve of the circularly polarized log-periodic antenna based on the rotation of the radiating dipole in this embodiment after electromagnetic simulation. It can be seen that the axial ratio coefficient is less than 3dB in the 1.23GHz-1.42GHz frequency band, which shows that circular polarization can be achieved in this frequency band and meets the requirements of circular polarization.

[0044] Figures 7 to 8 The radiation pattern at 1.25 GHz of the circularly polarized log-periodic antenna based on the rotation of the radiating dipole in this embodiment is shown after electromagnetic simulation. It can be seen that the antenna forms good left-handed circular polarization.

[0045] Figures 9 to 10 The radiation pattern at 1.3 GHz of the circularly polarized log-periodic antenna based on the rotation of the radiating dipole in this embodiment is shown after electromagnetic simulation. It can be seen that the antenna forms good left-handed circular polarization.

[0046] Figures 11 to 12 The radiation pattern at 1.4 GHz of the circularly polarized log-periodic antenna based on the rotation of the radiating dipole in this embodiment is shown after electromagnetic simulation. It can be seen that the antenna forms good left-handed circular polarization.

[0047] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A circularly polarized log-periodic antenna based on the rotation of a radiating dipole, characterized in that, include: Two first radiating oscillators (1), two second radiating oscillators (2), two third radiating oscillators (3), and two parallel convergent lines (4); the two parallel convergent lines (4) are horizontally and parallelly arranged along the y-axis, and the two first radiating oscillators (1) are respectively connected to the left ends of the upper and lower parallel convergent lines (4). The axes of the two first radiating oscillators (1) in the length direction are parallel to each other, and the angle between the axes of the two first radiating oscillators (1) in the length direction and the z-axis is 66°; the two second radiating oscillators (2) are respectively connected to the upper and lower parallel convergent lines (4). In the middle, the axes of the two second radiating oscillators (2) are parallel to each other in the length direction, and the angle between the axes of the two second radiating oscillators (2) and the z-axis is 30°; the two third radiating oscillators (3) are respectively connected in the middle of the upper and lower parallel convergence lines (4), the axes of the two third radiating oscillators (3) are parallel to each other, and the angle between the axes of the two third radiating oscillators (3) and the z-axis is 90°; the length ratio of the first radiating oscillator (1), the second radiating oscillator (2), and the third radiating oscillator (3) is 1:K:K 2 The ratio of the horizontal spacing between the first radiating oscillator (1), the second radiating oscillator (2), and the third radiating oscillator (3) is 1:K; The parallel line (4) is fed at one end near the third radiating element. The cross-feeding of the logarithmic periodic antenna is achieved through the structure of the parallel line (4). The electromagnetic wave energy input from the feeding point is transmitted from the third radiating element end to the first radiating element end along the parallel line (4). During the transmission process, each radiating element is excited in turn to form end-to-end radiation. The maximum radiation direction is from the first radiating element to the third radiating element. During the electromagnetic wave radiation process, there is a phase difference between the electromagnetic waves from the second radiating element (2) and the third radiating element (3) to the antenna null point. At the same time, when the electromagnetic wave propagates from the third radiating element end along the parallel line (4) to each group of radiating elements, the radiating elements are excited and radiate along the air. The radiating elements form the phase of the electromagnetic wave radiation in space by rotating the angle. When the generated electromagnetic wave phases combine to form a phase difference of 90°, the circular polarization characteristic of the antenna is realized.

2. The circularly polarized log-periodic antenna based on radiating dipole rotation according to claim 1, characterized in that, The first radiating oscillator (1), the second radiating oscillator (2), the third radiating oscillator (3), and the parallel convergence line (4) are all preformed metal columns.

3. The circularly polarized log-periodic antenna based on radiating dipole rotation according to claim 2, characterized in that, The preformed metal column is made of copper.

4. The circularly polarized log-periodic antenna based on radiating dipole rotation according to claim 2, characterized in that, The radius of the preformed metal column is 3mm.

5. The circularly polarized log-periodic antenna based on radiating dipole rotation according to claim 1, characterized in that, The value of K ranges from 0.8 to 0.

95.

6. The circularly polarized log-periodic antenna based on radiating dipole rotation according to claim 5, characterized in that, The length of the first radiating oscillator (1) is 100 mm, the length of the second radiating oscillator (2) is 85 mm, the length of the third radiating oscillator (3) is 72.25 mm, and the length of the parallel convergence line (4) is 104.5 mm.

7. The circularly polarized log-periodic antenna based on radiating dipole rotation according to claim 1, characterized in that, The horizontal axis of each of the parallel assembly lines (4) is 3.8 mm away from the horizontal center symmetry line of the antenna.

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