CN102820552B - A kind of broadband circular polarizer and antenna system - Google Patents

Abstract

The invention discloses a broadband circular polarizer, which comprises a multi-layer substrate, and a plurality of artificial microstructures are periodically arranged between adjacent substrates to form a multi-layer artificial microstructure layer, and the artificial microstructure is rectangular Metal sheet: the topological structure and size of the artificial microstructure of a single artificial microstructure layer are the same, and along the electromagnetic wave propagation direction, the size of the rectangular metal sheet of different layers of artificial microstructure layer gradually increases to the maximum value and then gradually decreases. The present invention designs a broadband circular polarizer by utilizing the principle of metamaterials. The broadband circular polarizer has a simple structure and can achieve a very good circular polarization effect within 30-40GHZ. At the same time, the invention also gradually increases the size of the artificial microstructure along the direction of electromagnetic wave propagation and then gradually decreases it, thereby meeting the requirements of electromagnetic wave propagation impedance matching, reducing electromagnetic wave reflection, and increasing gain.

Description

A Broadband Circular Polarizer and Antenna System

technical field

The invention relates to a circular polarizer, in particular to a broadband circular polarizer and an antenna system.

Background technique

With the development of modern satellite communication, remote control, and telemetry technology, a single polarization form is far from meeting the requirements of modern satellite communication. Circularly polarized waves can resist the interference of clouds, rain, and snow, and can show great advantages in Ka and higher bands. In electronic countermeasures, circularly polarized waves can detect and interfere with various linearly polarized and elliptically polarized electromagnetic waves of the enemy; installing circularly polarized antennas on violently swinging or rolling aircraft can also be used in harsh environments. Capture information, so circularly polarized waves are widely used in astronomy, aerospace communications, and remote sensing equipment.

The existing methods of generating circularly polarized waves include designing a feed source that can directly generate circularly polarized waves, or designing the shape of the patch antenna and the distance between the patch antenna and the feed source to generate circularly polarized waves. The design of the above method is complex and the frequency band of the circularly polarized wave generated is relatively narrow.

Contents of the invention

The technical problem to be solved by the present invention is to propose a broadband circular polarizer with simple structure, good circular polarization effect and wide frequency band, aiming at the above-mentioned shortcomings of the prior art.

The technical solution adopted by the present invention to solve the technical problem is to propose a broadband circular polarizer, which includes a multilayer substrate, and a plurality of artificial microstructures are periodically arranged between adjacent substrates to form a multilayer artificial microstructure. Structural layer, the artificial microstructure is a rectangular metal sheet; the artificial microstructure topology and size of the single-layer artificial microstructure layer are the same, and along the electromagnetic wave propagation direction, the size of the rectangular metal sheet of different artificial microstructure layers gradually increases to the maximum value gradually decreases.

Further, taking the rectangular metal sheet with the largest size as the central metal sheet, the artificial microstructures at the same distance from the central metal sheet have the same size.

Further, the width of the rectangular metal sheets is the same, and along the electromagnetic wave propagation direction, the length of the rectangular metal sheets gradually increases to a maximum value and then gradually decreases.

Further, the length of the rectangular metal sheet gradually increases to a maximum value in an arithmetic increasing manner.

Further, the central axes of the plurality of artificial microstructures coincide.

Further, the broadband circular polarizer includes nine layers of substrates, the minimum length of the rectangular metal sheet is 0.9 mm, the maximum length of the rectangular metal sheet is 1.2 mm, and the width is 0.2 mm.

Further, the thickness of the rectangular metal sheet is 0.01 to 0.02 mm, and the thickness of the substrate is 0.1 to 0.3 mm.

Further, the substrate is FR-4 material, F4B material, PS material, ferroelectric material, ferromagnetic material, ferrite material or ceramic material.

Further, the dielectric constant of the substrate is 3.4 to 4.0 at 34-35GHZ.

The present invention also provides an antenna system, which includes a feed source and the above-mentioned broadband circular polarizer arranged on the transmission path of the radiated electromagnetic wave of the feed source.

The present invention designs a broadband circular polarizer by utilizing the principle of metamaterials. The broadband circular polarizer has a simple structure and can achieve a very good circular polarization effect within 30-40GHZ. At the same time, the invention also gradually increases the size of the artificial microstructure along the propagation direction of the electromagnetic wave and then gradually reduces it, thereby meeting the requirements of electromagnetic wave propagation impedance matching, reducing electromagnetic wave reflection, and increasing gain.

Description of drawings

Figure 1 is a schematic diagram of the three-dimensional structure of the basic unit constituting the metamaterial;

Fig. 2 is the structural representation of the basic unit of a preferred embodiment of the broadband circular polarizer of the present invention;

Fig. 3 is a structural schematic diagram of the periodic arrangement of the first layer of rectangular metal sheets in Fig. 2;

Fig. 4 is the schematic diagram of the axial ratio simulation result of the broadband circular polarizer of the present invention;

Figure 5 is a schematic diagram of the axial ratio simulation results of the 33GHZ frequency point in Figure 4;

FIG. 6 is a schematic diagram of the axial ratio simulation results of the 34GHZ frequency point in FIG. 4 .

Detailed ways

Light, as a kind of electromagnetic wave, when it passes through the glass, because the wavelength of the light is much larger than the size of the atom, the glass can be described by the overall parameters of the glass, such as the refractive index, rather than the detailed parameters of the atoms that make up the glass response to light. Correspondingly, when studying the response of materials to other electromagnetic waves, the response of any structure in the material whose scale is much smaller than the wavelength of the electromagnetic wave to electromagnetic waves can also be described by the overall parameters of the material, such as the dielectric constant ε and magnetic permeability μ. By designing the structure of each point of the material, the dielectric constant and magnetic permeability of each point of the material are the same or different, so that the overall dielectric constant and magnetic permeability of the material are arranged in a certain order, and the regularly arranged magnetic permeability and magnetic permeability The electrical constant can make the material have a macroscopic response to electromagnetic waves, such as converging electromagnetic waves and diverging electromagnetic waves. Such materials with regularly arranged magnetic permeability and permittivity are called metamaterials.

As shown in FIG. 1 , FIG. 1 is a schematic diagram of a three-dimensional structure of a basic unit constituting a metamaterial. A basic unit of a metamaterial includes an artificial microstructure 2 and a substrate 1 to which the artificial microstructure is attached. In the present invention, the artificial microstructure is an artificial metal microstructure, and the artificial metal microstructure has a planar or three-dimensional topological structure that can respond to the electric field and/or magnetic field of the incident electromagnetic wave, and changes the performance of the artificial metal microstructure on each metamaterial basic unit. The pattern and/or size can change the response of each metamaterial elementary unit to incident electromagnetic waves. In a preferred embodiment, the artificial microstructure 2 can also be covered with a covering layer 3 , and the covering layer 3 , the artificial microstructure 2 and the substrate 1 constitute the basic unit of the metamaterial. Multiple basic units of metamaterials can be arranged according to certain rules to make metamaterials have a macroscopic response to electromagnetic waves. Since the metamaterial as a whole needs to have a macroscopic electromagnetic response to the incident electromagnetic wave, the response of each metamaterial basic unit to the incident electromagnetic wave needs to form a continuous response, which requires that the size of each metamaterial basic unit be less than one-fifth of the incident electromagnetic wave wavelength, preferably One tenth of the wavelength of the incident electromagnetic wave. In the description in this paragraph, the overall metamaterial is artificially divided into multiple metamaterial basic units, but it should be known that this division method is only for the convenience of description. Metamaterials can be spliced or assembled from multiple metamaterial basic units, or can be It can be formed by arranging the artificial metal microstructure periodically on the base material, and the process is simple and the cost is low. The periodic arrangement means that the artificial metal microstructures on the above-mentioned artificially divided basic units of metamaterials can generate continuous electromagnetic responses to incident electromagnetic waves.

The present invention uses the above-mentioned metamaterial principle to form a plurality of metamaterial sheets by designing multi-layer substrates and periodically arranging rectangular metal sheets between adjacent substrates, thereby converting the polarization mode of incident electromagnetic waves into circular polarization . In addition, in order to reduce the reflection of the incident electromagnetic wave and meet the requirements of impedance matching, along the propagation direction of the electromagnetic wave, the size of the rectangular metal sheet first gradually increases and then gradually decreases.

In the present invention, the rectangular metal sheet itself can be equivalent to the inductance value in the equivalent circuit, and the charge accumulation formed between adjacent and opposite rectangular metal sheets can be equivalent to the capacitance value in the equivalent circuit. By changing the size of the rectangular metal sheet, the thickness of the substrate, and the material of the substrate, the equivalent inductance and equivalent capacitance can be changed, thereby controlling the propagation characteristics of electromagnetic waves.

Please refer to Fig. 2 and Fig. 3. Fig. 2 is a schematic structural diagram of the basic unit of a preferred embodiment of the broadband circular polarizer of the present invention, and Fig. 3 is a schematic structural diagram of the periodic arrangement of the first layer of rectangular metal sheets in Fig. 2 . To illustrate the structure more clearly, Figure 2 uses a perspective view. In Fig. 2, the broadband circular polarizer includes nine substrates in total, and eight artificial microstructure layers are sandwiched between the nine substrates. The topological shape of each artificial microstructure is a rectangular metal sheet, and the central axes of each artificial microstructure coincide. The monolayer artificial microstructures are of the same topological shape and size. The dimensions of the rectangular metal sheets of different layers first gradually increase and then gradually decrease along the electromagnetic wave propagation direction. Preferably, with the largest rectangular metal sheet as the central metal sheet, the artificial microstructures at the same distance from the central metal sheet have the same size.

In this embodiment, the fifth layer of rectangular metal sheet has the largest size and is the central metal sheet, then the fourth layer of rectangular metal sheet and the sixth layer of rectangular metal sheet have the same size, and the third layer of rectangular metal sheet and the seventh layer of rectangular metal sheet have the same size. Same, the second layer of rectangular metal sheet and the eighth layer of rectangular metal sheet have the same size. It is conceivable that the broadband circular polarizer of the present invention may include other numbers of artificial microstructure layers according to different corresponding electromagnetic wave frequency bands and different requirements for precision of impedance matching performance.

Further, in this embodiment, the width of each rectangular metal sheet is the same, and only the length changes, and the change rule of the length is an arithmetic difference change. It is conceivable that the change rule of the length is also other change rules, such as proportional change, exponential change, and the like. In addition, the size change of the rectangular metal sheet can also be that the length is constant, the width is changed, or both the length and width are changed.

In this embodiment, the length dimension of the first layer of rectangular metal sheets to the fifth layer of rectangular metal sheets increases in an arithmetic progression. The minimum length dimension is 0.9mm and the maximum length dimension is 1.2mm; the width dimension is 0.2mm. The above dimensions can be different according to the frequency of the required response to electromagnetic waves and different requirements for impedance matching performance.

In this embodiment, the thickness of the rectangular metal sheet is 0.01 to 0.02 mm, the thickness of the base material is 0.1 to 0.3 mm, and the overall thickness of the broadband circular polarizer is only 2 to 3 mm, which can be easily applied to various feed sources superior.

The base material can be FR-4 material, F4B material, PS material, ferroelectric material, ferrite material, ferromagnetic material, etc. Preferably, the substrate material has a dielectric constant of 3.4 to 4.0 at 34-35 GHZ. The rectangular metal sheet can be various conductive metals such as copper, aluminum and silver.

Please refer to FIG. 4 , FIG. 5 , and FIG. 6 . FIG. 4 is a schematic diagram of the axial ratio simulation results of the broadband circular polarizer of the present invention. Figure 5 and Figure 6 are schematic diagrams of the axial ratio simulation results of the 33GHZ frequency point and the 34GHZ frequency point in Figure 4 . It can be seen from Fig. 4 that the axial ratio of the broadband circular polarizer of the present invention is below 3.5dB in the range of 30 to 40 GHZ, that is, the broadband circular polarizer of the present invention can achieve circular polarization in the frequency range of 30 to 40 GHZ. It can be seen from Fig. 5 and Fig. 6 that the circular polarization effect of the broadband circular polarizer of the present invention is excellent at 33GHZ and 34GHZ frequency points, the axial ratio at 33GHZ is only about 0.8dB, and the axial ratio at 34GHZ is only 0.74dB.

The present invention also provides an antenna system, which includes a feed source and the above-mentioned broadband circular polarizer. The feed source can be various feed sources that can radiate electromagnetic waves, such as horn antenna, patch antenna, microstrip antenna, etc. The broadband circular polarizer is placed on the path of the electromagnetic wave radiated by the feed source, and converts the electromagnetic wave radiated by the feed source into a circularly polarized electromagnetic wave. Since the broadband circular polarizer has thin thickness, good polarization effect and meets the requirements of impedance matching, it does not need to change the original structure of the feed source and occupies a small space.

Embodiments of the present invention have been described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementations, and the above-mentioned specific implementations are only illustrative, rather than restrictive, and those of ordinary skill in the art will Under the enlightenment of the present invention, many forms can also be made without departing from the gist of the present invention and the protection scope of the claims, and these all belong to the protection of the present invention.

Claims (9)

1. A broadband circular polarizer, characterized in that: it comprises a multilayer base material, and a plurality of artificial microstructures are periodically arranged between adjacent base materials to form a multilayer artificial microstructure layer, and the artificial microstructures is a rectangular metal sheet; the artificial microstructure topology and size of a single artificial microstructure layer are the same, along the direction of electromagnetic wave propagation, the size of rectangular metal sheets of different layers of artificial microstructure layers gradually increases to the maximum value and then gradually decreases, wherein, Taking the largest rectangular metal sheet as the central metal sheet, the artificial microstructures at the same distance from the central metal sheet have the same size. 2 . The broadband circular polarizer according to claim 1 , wherein the rectangular metal sheets have the same width, and along the direction of electromagnetic wave propagation, the length of the rectangular metal sheets gradually increases to a maximum value and then gradually decreases. 3 . 3. The broadband circular polarizer according to claim 2, characterized in that: the length of the rectangular metal sheet gradually increases to a maximum value in a manner of increasing with an equal difference. 4. The broadband circular polarizer according to claim 1, wherein the central axes of the plurality of artificial microstructures coincide. 5. The broadband circular polarizer according to claim 3, characterized in that: the broadband circular polarizer comprises nine layers of substrates, the minimum length of the rectangular metal sheet is 0.9 mm, and the maximum length of the rectangular metal sheet is 0.9 mm. 1.2 mm; width 0.2 mm. 6 . The broadband circular polarizer according to claim 5 , wherein the thickness of the rectangular metal sheet is 0.01 to 0.02 mm, and the thickness of the substrate is 0.1 to 0.3 mm. 7. The broadband circular polarizer according to claim 1, characterized in that: the base material is FR-4 material, F4B material, PS material, ferroelectric material, ferromagnetic material, ferrite material or ceramic material. 8 . The broadband circular polarizer according to claim 1 , wherein the dielectric constant of the substrate is 3.4 to 4.0 at 34-35 GHZ. 9. An antenna system, characterized in that: it includes a feed source and a broadband circular polarizer arranged on the transmission path of the feed source radiation electromagnetic wave, and the broadband circular polarizer is any one of claims 1 to 8 The broadband circular polarizer described in item.