CN108736154A - A kind of circular polarisation orbital angular momentum antenna - Google Patents

Abstract

The invention proposes a circularly polarized orbital angular momentum antenna, which is used to improve the anti-interference ability of the antenna, including N antenna units, N≥3, the antenna unit includes a dielectric material plate, and is printed on one side of the dielectric material plate The radiation patch and the radiation floor on the other side, wherein the shape of the radiation patch is a square with cut corners on any diagonal, which is connected to the radiation floor through a coaxial line; the N antenna elements are arranged in a hollow column structure, and the side of each antenna unit printed with a radiation patch is located outside the hollow cylindrical structure, forming a conformal array, the excitation signal amplitude of each antenna unit is equal, and adjacent antenna units have continuous phase delay Where l represents the number of modes carrying orbital angular momentum, satisfying -N/2<l<N/2. The invention can generate multiple modal vortex electromagnetic waves with dual characteristics of circular polarization and orbital angular momentum, and effectively improves the anti-interference ability of the antenna.

Description

A Circularly Polarized Orbital Angular Momentum Antenna

technical field

The invention belongs to the technical field of antennas, in particular to a circularly polarized orbital angular momentum antenna, which can be used in the technical field of wireless communication.

Background technique

According to the classical electrodynamic theory, electromagnetic radiation can carry not only energy but also angular momentum. The spin angular momentum SAM describing the polarization state and the orbital angular momentum OAM describing the helical phase structure together constitute the angular momentum. The orbital angular momentum Electromagnetic waves are called vortex electromagnetic waves. OAM multiplexing is a shared frequency spectrum resource technology in a common way. On the same carrier frequency, different orbital angular momentums are modulated and information is transmitted, which greatly improves the spectrum utilization efficiency and can solve the problem of spectrum resource shortage in the wireless communication field.

Due to the complex environment in which the antenna is applied, the traditional linearly polarized antenna sometimes cannot meet the requirements of communication. In contrast, the circularly polarized antenna can receive linearly polarized waves in any The linearly polarized antenna of the polarization direction receives, and has the orthogonality of rotation. Further research on the circular polarization characteristics of electromagnetic waves on the basis of OAM multiplexing technology can effectively improve the system's anti-interference ability, better solve the energy loss caused by different transmitting and receiving antenna angles, and maximize spectrum resources utilization rate.

At present, combined with the research progress of orbital angular momentum in related fields, there are mainly two ways to generate and emit orbital angular momentum vortex electromagnetic waves, namely the helical parabolic antenna and the array antenna. The former generates arbitrary patterns by adjusting the distance between the two ends of the parabolic opening. The orbital angular momentum radio beam; the latter generates the desired orbital angular momentum vortex electromagnetic wave by controlling the phase difference of the radiation field of the array element. However, the orbital angular momentum helical parabolic antenna is expensive and difficult to manufacture, and is not suitable for continuous phase control; in the array antenna, the radius of the dipole antenna array is as high as several meters to tens of meters, and a very small error is required when the array is arranged. To generate the expected modal value, the applicable site conditions are relatively harsh, and the application value in the actual communication system is not high. However, due to its planar structure, the microstrip antenna array has a low profile, small size, and the feeding method is simple and convenient. Controlling the input phase is of great significance in the application of orbital angular momentum antennas.

The key to realizing circularly polarized waves is to generate two linearly polarized waves with orthogonal directions, equal amplitude, and 90° phase difference. Which modes exist in a microstrip antenna depends entirely on the shape of the patch and the excitation model, a square patch fed from a single point on the diagonal, a square patch with diagonally cut corners, a directional patch with slots cut all around, and Two dipoles that are orthogonal to each other can generate circularly polarized radiation beams, but there is no response to how to use the circularly polarized radiation patch as the radiation patch of the orbital angular momentum antenna to generate circularly polarized vortex electromagnetic waves with good performance. Research.

The traditional orbital angular momentum antenna is a circular array composed of multiple radiating patches, by inputting an excitation signal with equal amplitude to each radiating patch, and adjacent radiating patches have a continuous phase delay Thus, vortex electromagnetic waves carrying orbital angular momentum are produced. For example, the application publication number is CN 107134659A, and the patent application titled "High-gain Orbital Angular Momentum Array Based on Multilayer Dielectric Plate" discloses a high-gain orbital angular momentum array based on a multilayer dielectric plate. There are P radiating patches arranged one-dimensionally along the Z axis, p is a positive integer greater than 2, and the spacing between each radiating patch is equal, and the antenna element passes through the feeding metal column and the input on the metal floor The ports are connected. The invention realizes the switching between various modes of orbital angular momentum vortex electromagnetic waves by controlling the input phase, but due to the simple structure of the radiation patch, only linearly polarized orbital angular momentum vortex electromagnetic waves can be realized, and the anti-interference ability Low.

Contents of the invention

The purpose of the present invention is to overcome the defects in the above-mentioned prior art, and propose a circularly polarized orbital angular momentum antenna, which is used to generate vortex electromagnetic waves with dual characteristics of circular polarization and orbital angular momentum, and improve the anti-interference ability of the antenna .

A circularly polarized orbital angular momentum antenna, comprising N antenna units 1, N≥3, said antenna unit 1 comprising a dielectric material plate 12, and a radiation patch 11 printed on one side of the dielectric material plate 12 and another The radiation floor 14 on the side, the shape of the radiation patch 11 is a square with cut corners on any diagonal, which is connected to the radiation floor 14 through the coaxial line 13; the N antenna units 1 are arranged in a hollow columnar structure , and the side of each antenna unit 1 printed with the radiation patch 11 is located outside the hollow columnar structure, forming a conformal array, the amplitude of the excitation signal of each antenna unit 1 is equal, and the adjacent antenna units 1 have a continuous phase delay Where l represents the number of modes carrying orbital angular momentum, and satisfies -N/2<l<N/2.

The above-mentioned circularly polarized orbital angular momentum antenna, the dielectric material plate 12, adopts a square plate with a coaxial 13 via hole at an off-center position, and the geometric center of the dielectric material plate 12 is the same as the geometric center of the radiation patch 11 coaxial.

In the above-mentioned circularly polarized orbital angular momentum antenna, the radiating patch 11 has a cut angle of an isosceles right triangle, and a U-shaped slit 111 is etched in the center of the radiating patch 11, and the U-shaped slit 111 The opening of 111 faces the side of the via hole provided on the dielectric material board 12 .

Compared with the prior art, the present invention has the following advantages:

1. The present invention adopts a hollow columnar structure arranged by multiple antenna units, and the side of each antenna unit printed with a radiation patch is located outside the hollow columnar structure, forming a conformal array, wherein the radiation patch adopts a square structure, And set the cut angle at any diagonal position, by giving each antenna unit an equal input amplitude, and adjacent antenna units have a continuous phase delay The excitation signal generates a vortex electromagnetic wave with dual characteristics of circular polarization and orbital angular momentum with good performance, which maximizes the utilization of spectrum resources and system capacity, and effectively improves the anti-interference ability of the antenna.

2. The present invention adds a U-shaped slit at the center of the radiation patch, and the opening of the U-shaped slit faces the side of the via hole provided on the dielectric material plate, thereby changing the conduction path of the surface current of the radiation patch and increasing multiple The resonance point effectively widens the impedance bandwidth and axial ratio bandwidth of the antenna.

Description of drawings

Fig. 1 is the overall structure schematic diagram of embodiment 1 of the present invention;

Fig. 2 is a structural schematic view of the antenna unit of the present invention;

Fig. 3 is a schematic structural diagram of the radiation patch of the present invention;

Fig. 4 is the S11 simulation result figure of embodiment 1 of the present invention;

Fig. 5 is the axial ratio simulation result figure of embodiment 1 of the present invention;

Fig. 6 is the radiation pattern of embodiment 1 of the present invention;

Fig. 7 is a diagram of electric field phase distribution in Embodiment 1 of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment, the present invention is described in further detail:

Example 1

With reference to Fig. 1, a kind of circular polarization orbital angular momentum antenna that the present invention proposes comprises eight antenna elements 1, and this antenna element 1 comprises a dielectric material plate 12, and a radiation patch 11 printed on one side of the dielectric material plate 12 and the radiant floor 14 on the other side, wherein the radiant patch 11 and the radiant floor 14 are connected by a coaxial line 13 . The antenna units 1 are arranged in a hollow columnar structure, and the side of each antenna unit 1 printed with a radiation patch 11 is located outside the hollow columnar structure, forming a conformal array. This structure can effectively suppress the mutual coupling between the units. The characteristics of the antenna unit 1 are maintained, and the performance of the antenna is improved.

Referring to Fig. 2, the geometric center of the radiation patch 11 is coaxial with the geometric center of the dielectric material plate 12, and the dielectric material plate 12 adopts a square plate with a coaxial 13 via hole located off the center, and a dielectric constant of 10.2 is selected. The overall size of the dielectric material plate is 80mm×80mm×9mm, and the radiant floor 14 is the same size as the dielectric material plate 12, the deviation distance of the coaxial line 13 is 20mm, and its radius is 0.5mm. According to the microstrip antenna formula, the resonant frequency f ₀ of the microstrip antenna is proportional to ε _r - ^1/2 , so for a fixed frequency, the use of a dielectric substrate with a high dielectric constant can effectively reduce the size of the antenna.

Referring to Fig. 3, the radiation patch 11 is a square structure with a side length of 60mm. In order to excite two orthogonally polarized electromagnetic waves with equal amplitude and a phase difference of 90°, the radiation patch 11 is placed in the upper left corner and the lower right corner respectively. Two isosceles right triangles are cut off, and the length of the sides of the triangles is 7.2mm, and the position of the coaxial line 13 is adjusted to generate a circularly polarized radiation beam with good performance. Add a U-shaped slit 111 on the radiation patch 11, the long side e=11mm of the U-shaped slit 111, the short side c=6.5mm, the width w1=1mm, and its opening faces the side of the via hole set on the dielectric material plate , the U-shaped slot 111 can change the conduction path of the current, increase multiple resonance points, and effectively widen the impedance bandwidth and axial ratio bandwidth of the antenna.

The necessary condition for generating vortex electromagnetic waves carrying orbital angular momentum is to input excitation signals with equal amplitudes to each antenna unit 1, and adjacent antenna units 1 have a continuous phase delay thus adding a phase rotation factor to normal electromagnetic waves Where l represents the number of modes carrying orbital angular momentum, satisfying -N/2<l<N/2, N represents the number of antenna units 1, and the number of antenna units 1 determines the maximum value of the modes that can generate orbital angular momentum.

The number N=8 of the antenna unit 1 of the present invention, and the pattern number l=1, according to the necessary condition of producing the vortex electromagnetic wave carrying the orbital angular momentum, the phase delay of the adjacent unit can be obtained Assuming that the initial phase φ=0 of the first antenna unit 1, each unit sequentially inputs excitation signals with phases of 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°, and The amplitudes are equal, and due to the radiation patch 11 with a cut angle and the form of a conformal array, the coupling between the units is effectively avoided, and the circular polarization characteristics of the antenna unit 1 are maintained, and a circle with an orbital angular momentum mode number of 1 can be generated. Polarized vortex electromagnetic waves, due to the phase rotation factor At this time, the electromagnetic wave is no longer a planar structure, but rotates around the propagation direction, presenting a spiral electric field phase distribution, and the divergence characteristics of the vortex electromagnetic wave itself, the electromagnetic wave with the orbital angular momentum mode number l=1 does not It is an omnidirectional radiation pattern, but there is a certain hollow phenomenon.

The structure of the antenna in embodiment 2 is the same as that of embodiment 1, and the following parameters have been adjusted:

The number of antenna elements 1 is N=4, and the number of modes is set to l=1/2. According to the necessary conditions for generating vortex electromagnetic waves carrying orbital angular momentum, the phase delay of adjacent elements can be obtained as Assuming that there is an initial phase φ=0 of the first antenna unit 1, each unit sequentially inputs excitation signals with phases of 0°, 45°, 90°, and 135°, and the amplitudes are equal, and the orbital angular momentum mode number is 2. Circularly polarized vortex electromagnetic waves.

Effect of the present invention can be further explained in conjunction with simulation result:

1. Simulation content

1.1 Using the commercial simulation software HFSS_13.0 to simulate and calculate the S11 parameter of the above-mentioned embodiment 1, the result is shown in FIG. 4 .

1.2 Use the commercial simulation software HFSS_13.0 to simulate and calculate the axial ratio parameters of the above-mentioned embodiment 1, and the results are shown in FIG. 5 .

1.3 Using the commercial simulation software HFSS_13.0 to simulate the radiation pattern of the above-mentioned embodiment 1, the result is shown in FIG. 6 .

1.4 Using the commercial simulation software HFSS_13.0 to simulate and calculate the phase distribution of the electric field in the above-mentioned embodiment 1, the result is shown in FIG. 7 .

2. Simulation results

Referring to FIG. 4 , taking S11<-10dB as the standard, the impedance bandwidth of the antenna in Embodiment 1 is 1.46GHz-1.65GHz, and the relative bandwidth is 12%.

Referring to FIG. 5 , taking the axial ratio AR<3 as the standard, the axial ratio bandwidth of the antenna in Embodiment 1 is 1.46 GHz-1.65 GHz, which meets the requirement of circular polarization within the impedance bandwidth.

Referring to Fig. 6, the maximum radiation direction of the antenna in Embodiment 1 is always perpendicular to the surface of the radiation unit, and there is a certain hollow phenomenon, and the maximum gain is 3.1dB.

Referring to FIG. 7 , the electric field phase of the antenna in Embodiment 1 is distributed in a spiral shape.

The above simulation results show that the antenna of the present invention has ideal impedance bandwidth and axial ratio bandwidth, and meets the requirements of the orbital angular momentum antenna.

Claims (3)

1. A circularly polarized orbital angular momentum antenna is characterized in that, comprises N antenna units (1), N≥3, and said antenna unit (1) comprises a dielectric material plate (12), and is printed on a dielectric material The radiant patch (11) on one side of the board (12) and the radiant floor (14) on the other side, the shape of the radiant patch (11) is a square with chamfered corners on any diagonal, which is consistent with the radiant floor (14) Connected by a coaxial line (13); the N antenna units (1) are arranged in a hollow columnar structure, and the side of each antenna unit (1) printed with a radiation patch (11) is located in the hollow columnar structure , forming a conformal array, the excitation signal amplitude of each antenna element (1) is equal, and the adjacent antenna elements (1) have continuous phase delay Where l represents the number of modes carrying orbital angular momentum, and satisfies -N/2<l<N/2. 2. a kind of circularly polarized orbital angular momentum antenna according to claim 1, is characterized in that, described dielectric material plate (12), adopts the square sheet material that off-centre position is provided with coaxial line (13) via hole, The geometric center of the dielectric material plate (12) is coaxial with the geometric center of the radiation patch (11). 3. a kind of circularly polarized orbital angular momentum antenna according to claim 2, is characterized in that, described radiation patch (11), the cut angle that it cuts off is an isosceles right triangle, and this radiation patch (11 ) is etched with a U-shaped slit (111), and the opening of the U-shaped slit (111) faces the side of the via hole provided on the dielectric material plate (12).