An omni-directional scanning leaky-wave antenna based on unidirectional edge modes

Abstract

The application belongs to the technical field of antennas, and discloses an omnidirectional scanning leaky-wave antenna based on a unidirectional edge mode, which comprises a unidirectional waveguide composed of a metal layer, an air layer and a photonic crystal which are sequentially spliced, wherein the unidirectional waveguide has a unidirectional edge mode in an air light cone, the photonic crystal is composed of square dielectric columns arranged periodically and embedded in a yttrium iron garnet background, a static magnetic field is applied to the photonic crystal along the z direction, and the metal layer of the unidirectional waveguide is provided with periodic hollow holes. The application has the advantages of simple structure, low photonic crystal band gap, and the ability of full-space scanning from a backward end-fire, lateral radiation and then a forward end-fire.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of antennas, and particularly relates to an omnidirectional scanning leaky-wave antenna based on a unidirectional edge mode. BACKGROUND

[0002] The unidirectional edge mode refers to an electromagnetic wave mode that can only propagate in one direction, and it has an immune function for reverse scattering caused by defects (or bending) because there is no reverse propagation mode in the system.

[0003] Non-reciprocal devices are usually indispensable important elements in optical systems, and ideal non-reciprocal devices can ensure that signals are transmitted in one direction in the system. In addition to eliminating destructive feedback to the transmitting source, they can also greatly simplify the design of optical systems by suppressing multiple-path reflections between devices, and greatly improve the stability of the system to manufacturing defects and environmental changes.

[0004] The frequency characteristics of a photonic crystal are closely related to its unit cell structure (such as hole size and arrangement). For example, changing the period length or porosity of the photonic crystal can adjust its bandgap range and corresponding frequency.

[0005] At present, leaky-wave antennas mainly include leaky-wave antennas based on artificial surface plasmons, traditional periodic microstrip leaky-wave antennas, etc., but photonic crystal leaky-wave antennas based on unidirectional edge modes are rarely mentioned. How to design them to have excellent leaky-wave performance is a challenging problem.

[0006] Chinese patent application No. CN117410692A discloses a "lateral beam scanning leaky-wave antenna based on yttrium iron garnet cylindrical array", which can realize lateral beam scanning, but the beam scanning angle of its structure is very limited, and the leakage mode is not simple enough.

[0007] The photonic crystal leaky-wave antennas proposed in SCI papers "Broadside Radiation From Chern Photonic Topological Insulators" and "Tunable directional radiation and reception based on magneto-optical photonic crystal waveguides" are subject to their photonic crystal structure. The photonic bandgap position is relatively high, and it cannot pass through the entire air light cone, and the scanable angle is very limited. SUMMARY

[0008] The application aims to provide an omni-directional scanning leaky-wave antenna based on a single-direction edge mode, which has simple structure, low photonic band gap, and full-space scanning capability from back end-fire, lateral radiation, and then front end-fire.

[0009] To achieve the above-mentioned purpose, the technical solution adopted by the application is as follows:

[0010] An omni-directional scanning leaky-wave antenna based on a single-direction edge mode comprises a single-direction waveguide composed of a metal layer, an air layer, and a photonic crystal which are sequentially spliced, the single-direction waveguide has a single-direction edge mode in an air light cone, the photonic crystal is composed of square dielectric columns embedded in a yttrium iron garnet background in a periodic arrangement, and the photonic crystal applies a static magnetic field along the z direction, and the metal layer of the single-direction waveguide is provided with periodic hollow holes.

[0011] The following also provides several optional modes, but not as an additional limitation to the above general solution, just a further supplement or preferred, without technical or logical contradiction, each optional mode can be combined with the above general solution alone, and can also be combined between multiple optional modes.

[0012] As preferred, the periodic hollow holes are located in the middle part of the metal layer.

[0013] As preferred, the lattice constant of the photonic crystal is a, and the side length of the square dielectric column is 0.25a-0.45a.

[0014] As preferred, the periodic constant of the periodic hollow holes is a, and the position of each hollow hole corresponds to the position of the square dielectric column.

[0015] As preferred, the thickness of the air layer is 0.85a-1.00a.

[0016] As preferred, the dispersion curve of the single-direction waveguide under the single-direction edge mode passes through the entire air light cone line and is continuous at k=0, k being the wave vector.

[0017] As preferred, the relative dielectric constant of the square dielectric column is relatively high, ranging from 170 to 200.

[0018] As preferred, the edge height of the photonic crystal is h, and h>0.

[0019] As preferred, the omni-directional scanning leaky-wave antenna has a full-space scanning mode from back to front under the condition that the magnetic induction intensity of the static magnetic field is fixed and the working frequency is increased; or has a full-space scanning mode from back to front under the condition that the working frequency is fixed and the magnetic induction intensity of the static magnetic field is decreased.

[0020] The application provides an omni-directional scanning leaky-wave antenna based on a one-way edge mode, which supports the one-way edge mode in an air light cone, and a dispersion curve passes through the whole air light cone line and is continuous at a wave vector k=0. A yttrium-iron-garnet (YIG) photonic crystal has a wide band gap characteristic, and the band gap position is significantly lowered. The leaky-wave antenna is simple to operate, has a full-space scanning capability from a backward end-fire, a lateral radiation and then a forward end-fire, supports a fixed magnetic frequency beam omni-directional scanning and a fixed frequency magnetic field beam omni-directional scanning, and can be applied to the fields of radars, beam controls, space optical communications and the like. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 FIG. 1 is a two-dimensional structure schematic diagram of a two-dimensional structure of the omni-directional scanning leaky-wave antenna based on the one-way edge mode of the application;

[0022] Figure 2 FIG. 2 is a two-dimensional structure schematic diagram of a periodic unit structure of the omni-directional scanning leaky-wave antenna based on the one-way edge mode of the application;

[0023] Figure 3 FIG. 3 is a two-dimensional structure schematic diagram of a photonic crystal unit cell of the application;

[0024] Figure 4 FIG. 4 is an energy band diagram of the photonic crystal of the application without an external magnetic field, wherein (a) in FIG. 4 is the energy band diagram of the photonic crystal of the application without an external magnetic field, Figure 4 FIG. 5 is an energy band diagram of the photonic crystal of the application with an external magnetic field, wherein (b) in FIG. 5 is the energy band diagram of the photonic crystal of the application with an external magnetic field;

[0025] Figure 5 FIG. 6 is a one-way waveguide structure schematic diagram, wherein (a) in FIG. 6 is the one-way waveguide structure schematic diagram, Figure 5 FIG. 7 is a one-way waveguide transmission schematic diagram, wherein (b) in FIG. 7 is the one-way waveguide transmission schematic diagram, Figure 5 FIG. 8 is a one-way waveguide edge mode dispersion curve diagram, wherein (c) in FIG. 8 is the one-way waveguide edge mode dispersion curve diagram;

[0026] Figure 6 FIG. 9 is an edge mode dispersion curve diagram of the omni-directional scanning leaky-wave antenna of the application;

[0027] Figure 7 FIG. 10 is a far-field gain diagram of the omni-directional scanning leaky-wave antenna of the application under different frequencies, wherein (a) in FIG. 10 is the far-field gain diagram of the omni-directional scanning leaky-wave antenna of the application under different frequencies, Figure 7 FIG. 11 is a backward, lateral and forward radiation schematic diagram of the omni-directional scanning leaky-wave antenna of the application under different frequencies, wherein (b) in FIG. 11 is the backward, lateral and forward radiation schematic diagram of the omni-directional scanning leaky-wave antenna of the application under different frequencies;

[0028] Figure 8 FIG. 12 is a far-field gain diagram of the omni-directional scanning leaky-wave antenna of the application under different magnetic fields, wherein (a) in FIG. 12 is the far-field gain diagram of the omni-directional scanning leaky-wave antenna of the application under different magnetic fields, Figure 8 FIG. 13 is a backward, lateral and forward radiation schematic diagram of the omni-directional scanning leaky-wave antenna of the application under different magnetic fields, wherein (b) in FIG. 13 is the backward, lateral and forward radiation schematic diagram of the omni-directional scanning leaky-wave antenna of the application under different magnetic fields. DETAILED DESCRIPTION

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0031] Example 1:

[0032] like Figures 1-2 As shown, the omnidirectional scanning leaky wave antenna based on unidirectional edge mode in this embodiment includes a unidirectional waveguide composed of a metal layer, an air layer, and a photonic crystal sequentially spliced ​​together. The photonic crystal layer of the unidirectional waveguide is composed of a periodic array of square dielectric pillars in a YIG background, and an external magnetic field is applied in the z-direction. The cross-sectional length of the unidirectional waveguide is set in the x-direction, and the width is set in the y-direction; therefore, the z-direction is perpendicular to the xy-plane. Figure 3 As shown, the photonic crystal has a lattice constant of a = 0.00672 mm, a square dielectric pillar side length of 0.35 a, and an operating frequency of 4.28 GHz. The band structure of the photonic crystal in this embodiment is shown below when no external magnetic field is applied. Figure 4 As shown in (a), no obvious photonic bandgap was observed within a certain frequency range. When an external magnetic field (static magnetic field, magnitude 1600 G) was applied, the bandgap diagram of the photonic crystal changed as follows: Figure 4 As shown in (b), a wide photonic bandgap of 9.3% can be generated, and the bandgap position is significantly lower than that of conventional photonic crystals supporting unidirectional edge modes. The air layer thickness is d=0.9288a, and the outermost layer is truncated with a metal sheet.

[0033] In this embodiment, the photonic crystal YIG exhibits gyromagnetic properties under the influence of an external magnetic field, and its relative permeability has the following form:

[0034]

[0035]

[0036] In the formula, The relative permeability, The virtual part, and These are the first parameter and the second parameter, respectively, and in this embodiment... , , characteristic angular frequency of YIG material, precession angular frequency, where gyromagnetic ratio, magnetic field strength of external magnetic field, angular frequency, loss of YIG material.

[0037] In order to have obvious effect, the relative dielectric constant of YIG in the embodiment is , the relative dielectric constant of square medium is .

[0038] As shown in Figure 5 , the embodiment cuts the photonic crystal boundary, so that the YIG edge height h = 0.41275a. At this time, the structure of the single-mode waveguide is shown in Figure 5 (a), and thus the single-mode waveguide supports a single-mode edge mode in the air optical cone, as shown in Figure 5 (b), the single-mode edge mode is at the edge of the photonic crystal and air, and is a leaky mode, as shown in Figure 5 (c), the leaky mode dispersion curve passes through the entire air optical cone line and is continuous at k = 0, so it is very convenient to realize the leakage of the mode by opening holes in the metal sheet, and entering the free space.

[0039] In order to realize the leakage, the embodiment periodically punches the metal layer in the single-mode waveguide, where the period constant is a, and the aperture width w = 0.354a. As shown in Figure 6 , the leaky-wave antenna of the embodiment has a dispersion curve that passes through the entire air optical cone line and is continuous at k = 0 in the leaky mode. The metal layer of the embodiment is simulated as a perfect electric conductor (Perfect Electric Conductor), and the dispersion relationship, far-field amplitude and transmission simulation of the leaky unit structure of the embodiment are obtained by finite element simulation numerical calculation.

[0040] By fixing the external magnetic field (the magnetic induction strength of the external magnetic field is fixed at 1600G) and adjusting the working frequency, the leaky-wave antenna realizes the full-space scanning capability from the backward end-fire, lateral radiation, and then the forward end-fire. The leaky-wave result is shown in Figure 7 . Figure 7 (a) of shows the radiation angle and gain of the leaky-wave antenna at different frequencies. It can be seen that the leaky-wave antenna in the embodiment realizes the full-space omnidirectional (180-degree) scanning from -90 degrees to 90 degrees, and has high gain; Figure 7 (b) shows the schematic of the backward end-fire, lateral radiation, and forward end-fire of the leaky-wave antenna at different frequencies (4.263GHz, 4.275GHz and 4.285GHz).

[0041] Example 2:

[0042] Based on the leaky-wave antenna structure of Example 1, this example adjusts the magnetic induction intensity of the external magnetic field by fixing the operating frequency (the operating frequency is fixed at 4.28 GHz), and the leaky-wave antenna realizes the full-space scanning capability from the backward end-fire, lateral radiation, and then the forward end-fire. The leaky-wave result is shown in Figure 8 Figure 8 (a) in FIG. 6 shows the radiation angle and gain of the omnidirectional scanning leaky-wave antenna under different magnetic fields. It can be seen that the leaky-wave antenna in this example realizes the omnidirectional (180-degree) scanning of the upper half space from -90 degrees to 90 degrees, and the gain is high. Figure 8 (b) in FIG. 6 shows the schematic of the backward end-fire, lateral radiation, and forward end-fire of the leaky-wave antenna under different magnetic fields (1611G, 1600G, and 1592G).

[0043] The technical features of the above-described embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present disclosure.

[0044] The above-described embodiments only express several embodiments of the present disclosure, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the present disclosure. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present disclosure, a number of modifications and improvements can be made, which are all within the scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the appended claims.​

Claims

1. A unidirectional edge mode based omni-directional scanning leaky-wave antenna, characterized in that, The omnidirectional scanning leaky-wave antenna based on the unidirectional edge mode comprises a unidirectional waveguide composed of a metal layer, an air layer and a photonic crystal in sequence, the unidirectional waveguide has a unidirectional edge mode in an air light cone, the photonic crystal is composed of square dielectric columns arranged periodically in a yttrium iron garnet background, and the photonic crystal applies a static magnetic field along the z direction, the metal layer of the unidirectional waveguide is provided with periodic hollow holes, and a dispersion curve of the unidirectional waveguide under the unidirectional edge mode continuously passes through the whole air light cone line and is continuous at k=0, wherein k is a wave vector.

2. The unidirectional edge mode based omni-directional scanning leaky-wave antenna according to claim 1, wherein, The periodic hollow holes are located in the middle part of the metal layer.

3. The unidirectional edge mode based omni-directional scanning leaky-wave antenna according to claim 1, wherein, The lattice constant of the photonic crystal is a, and the side length of the square dielectric column is 0.25a-0.45a.

4. The unidirectional edge mode based omni-directional scanning leaky-wave antenna according to claim 3, wherein, The periodic hollow holes have a period constant a, and the positions of the hollow holes correspond to the positions of the square dielectric columns.

5. The unidirectional edge mode based omni-directional scanning leaky-wave antenna according to claim 3, wherein, The thickness of the air layer is 0.85a-1.00a.

6. The unidirectional edge mode based omni-directional scanning leaky-wave antenna according to claim 1, wherein, The relative dielectric constant of the square dielectric column is 170-200.

7. The unidirectional edge mode based omni-directional scanning leaky-wave antenna according to claim 1, wherein, The edge height of the photonic crystal is h, and h>0.

8. The unidirectional edge mode based omni-directional scanning leaky-wave antenna according to claim 1, wherein, The omnidirectional scanning leaky-wave antenna has a full-space scanning mode from rearward to forward with the increase of the working frequency under the fixed magnetic induction intensity of the static magnetic field, or has a full-space scanning mode from rearward to forward with the decrease of the magnetic induction intensity of the static magnetic field under the fixed working frequency.

Images