CN210576457U

CN210576457U - Broadband antenna isolator based on metamaterial

Info

Publication number: CN210576457U
Application number: CN201921179101.4U
Authority: CN
Inventors: 蔡伟奇; 张富利; 樊元成; 付全红; 朱维; 杨蕤生
Original assignee: Northwestern Polytechnical University
Current assignee: Northwestern Polytechnical University
Priority date: 2019-07-25
Filing date: 2019-07-25
Publication date: 2020-05-19
Anticipated expiration: 2029-07-25

Abstract

The utility model relates to a broadband antenna isolator based on metamaterial, which is positioned between two antennas, is placed on an antenna floor, and comprises a metamaterial resonance unit and a dielectric substrate when the antenna isolator is vertical to the direction of the antenna substrate, wherein the metamaterial resonance unit is printed on the surface of the dielectric substrate; the metamaterial resonance unit is in the shape of an open ring, the position of the open ring is arranged at the center of the bottom edge of the ring, the direction of the open ring points to the antenna floor, the total length of the open ring is one wavelength, the width of the open ring is 1mm, and the length of the open ring is 1 mm. The utility model discloses utilize the metal resonance unit to fix on the medium base plate, based on the polarization mode of antenna, put the antenna division board, utilize resonance unit to realize the improvement more than 5dB to near field radiation's the effectual improvement at 4G (1.8GHz-2.6GHz) frequency channel. The distance between the antennas can be reduced, and simultaneously, the high isolation between the antennas can be kept, so that the antennas can be miniaturized.

Description

Broadband antenna isolator based on metamaterial

Technical Field

The invention belongs to the technical field of antennas, relates to a metamaterial electromagnetic resonance antenna isolation method for broadband work, and particularly relates to an antenna isolation device for broadband work.

Background

The metamaterial is a new field at present, and refers to artificial composite structures or composite materials with extraordinary physical properties which are not possessed by natural materials, and the extraordinary physical properties which are not possessed by the natural materials can be realized through the periodically arranged sub-wavelength structure arrays, so that the metamaterial provides a new breakthrough in the scientific fields of physics, electronics, food, biology, medicine and the like.

With the rapid development of electronic technology, people have raised higher requirements on radar, wireless communication technology, and communication system miniaturization and communication quality. In the field of vehicle-mounted antennas, intelligentization and informatization are deepened continuously, the number and the types of the vehicle-mounted antennas are increased continuously, the requirement on electromagnetic isolation among multiple antenna systems is improved continuously in order to ensure that mutual interference among the antennas is small enough, and how to ensure the isolation among the antennas becomes an important subject under the condition that the size of an original antenna system is kept unchanged or reduced.

The coupling between closely spaced vehicle antennas (near-field coupling) is inversely proportional to the third power of the distance (far field is quadratic), and the operating state of any device is affected by this mutual coupling. This effect is more pronounced for antennas that are sensitive to electromagnetic field transmission and reception, and in general, for two antennas that are close and operate independently, this strong coupling is considered as a noise that needs to be suppressed by means of isolation or the like.

The antenna isolation mode mainly comprises polarization isolation, filling structure isolation, feed network isolation and the like, in addition, the rapid development of the metamaterial in the last two decades shows the unique characteristics which are not possessed by the traditional material through the artificially and delicately designed periodic structure, and a new thought of material and structure research is given, so that a series of Metamaterials (Metamaterials) with unique performance are developed. The novel materials are characterized in that the unusual macroscopic properties thereof are derived from the elaborate design of the microstructure configuration rather than the material properties of the structure itself. The metal or dielectric-based artificial microstructure can show negative electromagnetic parameters (negative dielectric constant, negative refractive index, negative magnetic permeability and the like) under the excitation of electromagnetic waves/light waves, so that the understanding range of the electromagnetic waves/light waves regulation and control mode is greatly expanded, and the development of novel electromagnetic functional devices such as superlenses, cloaks and the like is promoted. The field where the metamaterial is most applied is antennas, the radiation characteristics of the antennas are regulated and controlled by using near-zero refraction materials, and the miniaturization research of the antennas is realized by using electromagnetic super surfaces. The uniqueness and tailorability of equivalent parameters make metamaterials play an important role in the modulation of various types of waves (fields).

The size and the spatial position of the metamaterial resonance unit are reasonably regulated and controlled based on the radiation mode of the antenna array by combining the unique electromagnetic corresponding behaviors of the metamaterial, so that the mutual coupling between the antenna arrays can be effectively weakened in a frequency band with specific requirements, the antenna isolation can be effectively improved, or the distance between the antenna arrays can be reduced.

Aiming at the problem of mutual coupling in further miniaturization of a 4G multi-antenna system, based on the research foundation of earlier application of a research team on functional metamaterials, super surfaces and electromagnetic mutual coupling of the functional metamaterials, the super surfaces and the electromagnetic mutual coupling in an electromagnetic radiation control and complex structure, the invention designs and prepares the broadband metamaterial isolator of the LTE antenna aiming at 4G signals, places a metamaterial isolation layer between LTE antenna arrays so that the metamaterial isolation layer obviously weakens the mutual coupling between the antennas in a wide frequency band in which the antennas work, improves the isolation degree, and realizes the miniaturization of the antenna arrays under the condition of not influencing the basic performance of the antennas.

Disclosure of Invention

Technical problem to be solved

In order to solve the problems that the isolation frequency band is narrow, the isolation effect is poor and the radiation performance of an original antenna can be affected in the prior art, the invention provides a metamaterial-based broadband antenna isolator, the radiation mode of an antenna array is considered, the structure of a metamaterial resonance unit is selected and printed on an isolator substrate, the placement direction of the metamaterial resonance unit is perpendicular to the direction of a radiation electric field (namely perpendicular to the placement plane of the antenna array) and is placed on the antenna substrate, and the isolation improvement of improving the isolation by more than 5dB at the frequency band of 1.8GHz-2.6GHz can be realized (the effective isolation at other frequency bands can be realized by reasonably changing the size of a split ring).

Technical scheme

A broadband antenna isolator based on a metamaterial is characterized in that the broadband antenna isolator is arranged between two antennas and placed on an antenna floor, and when the broadband antenna isolator is perpendicular to the direction of an antenna substrate, the broadband antenna isolator comprises a metamaterial resonance unit and a dielectric substrate, wherein the metamaterial resonance unit is printed on the surface of the dielectric substrate; the metamaterial resonance unit is in the shape of an open ring, the position of the open ring is arranged at the center of the bottom edge of the ring, the direction of the open ring points to the antenna floor, the total length of the open ring is one wavelength, the width of the open ring is 1mm, and the length of the open ring is 1 mm.

The split ring is triangular, circular, rectangular, rhombic or oval.

The metamaterial resonance unit is made of metal materials.

The dielectric substrate is made of teflon, FR4 or F4B.

Advantageous effects

The invention provides a broadband antenna isolator based on a metamaterial, which is not used for inhibiting the transmission of surface waves by designing on a dielectric plate in the prior art, but mainly plays a role in inhibiting electromagnetic interference among antennas in space, and utilizes the unique singular physical characteristics of the metamaterial to improve the isolation among the antennas and simultaneously influence the feed performance of the antennas to the minimum extent. The beneficial effects are as follows:

1. the characteristic of near-field regulation and control is realized based on metal structure resonance, the isolation degree of more than 5dB of 1.8-2.6GHz is improved by utilizing the electromagnetic field coupling between the metamaterial resonance unit and the antenna array and the resonance characteristic of the metamaterial isolation plate.

2. The invention needs to prepare samples with corresponding sizes and structures, has mature processing technology, controllable cost, can realize high-efficiency microwave modulation and stable performance.

3. After the metamaterial isolation plates are added, the distance between the antenna arrays is reduced, the high-efficiency isolation of a wide frequency band (1.8-2.6GHz) can be still realized, and the mutual interference between the antenna arrays is weakened.

Drawings

Fig. 1 is a structural diagram of a metamaterial-based antenna isolator according to the present invention.

Fig. 2 is a schematic diagram of the placement of the metamaterial antenna isolator in a 4G antenna array according to the present invention.

FIG. 3 is a schematic diagram of the resonance characteristics of the metamaterial isolator in accordance with the present invention.

Fig. 4 is a schematic diagram of the true isolation variation of the antenna after the metamaterial isolator is added in the invention.

Detailed Description

The invention will now be further described with reference to the following examples and drawings:

researches find that the metamaterial, the metamaterial surface and the research foundation of the metamaterial, the metamaterial surface and the application of the metamaterial in the aspects of electromagnetic radiation control and electromagnetic mutual coupling in a complex structure, and the metamaterial isolation layer is arranged between the antennas, so that the mutual coupling between the antennas is obviously weakened in a plurality of frequency bands of the work of the antennas, the isolation degree is improved, and the reduction of the whole physical size of the antenna group is realized. According to the invention, the metamaterial electromagnetic resonance unit isolator with the corresponding shape and size is designed by utilizing the electromagnetic resonance of the metal structure according to the field distribution condition of the antenna near field, so that the working frequency of the metamaterial electromagnetic resonance unit is close to that of the antenna array, thereby inhibiting the near field coupling between the antenna arrays, improving the isolation of the antenna and reducing the broadband mutual interference between the antenna arrays.

The principle structure of the invention is realized as the attached figure 2: the antenna array is a double-antenna unit array, the antenna array is selected from a common 4G vehicle-mounted antenna on the market, the working frequency of the antenna array is mainly in a 4G frequency band, wherein the frequency range is 1.8-2.6GHz, simulation modeling calculation and experimental test are respectively carried out on the antenna, and the isolation between the antenna arrays is found to be about-15 dBi at the frequency band of 1.8-2.6GHz, and the structure is as shown in the attached figure 1: the metamaterial isolation plate is schematically shown in the drawing, split ring metal is printed on a teflon substrate, the near-field electric field distribution of a 4G antenna array is considered, the opening of the split resonant ring of the isolation plate is selected to be placed towards the direction of an antenna floor, and based on the resonance characteristics of the metamaterial units in the isolation plate, mutual coupling between antennas can be effectively inhibited, and the isolation degree between the antenna arrays is improved. The performance is shown in figure 3, the resonance characteristic of the metamaterial isolation plate is based on the required working frequency requirement, and the resonance unit capable of effectively working near the 4G frequency band is optimally designed according to the structural parameters. Considering the mutual coupling between the metamaterial isolation plate and the antenna array, as shown in fig. 4, the metamaterial isolation plate is placed between the antenna arrays, and comparing the resonance characteristic change of the antenna arrays, it can be seen that the isolation degree is improved by more than 5dB in the frequency band of 1.8-2.6 GHz. The metamaterial isolation plate effectively reduces the isolation degree between the antenna arrays, and provides an efficient method for the development trend of miniaturization of the antenna arrays at present.

Referring to fig. 1-4, the broadband metamaterial antenna isolator of the present invention is characterized in that a metamaterial resonance unit 1 is fixed on a dielectric substrate 2, and the dielectric substrate 2 is vertically disposed on an antenna floor.

The invention is applied to reducing the mutual coupling of a multi-antenna system. In a multi-antenna system, due to the reason of near-field radiation, mutual coupling exists between the antennas, and the isolation degree between the antennas can be effectively reduced by designing the isolation board of the electromagnetic resonance unit based on the design. The electromagnetic resonance unit 1 is fixed on the dielectric substrate 2, when the opening of the electromagnetic resonance unit 1 is parallel to the polarization direction of the antenna, single-frequency-band ultrahigh isolation can be realized, and when the opening of the electromagnetic resonance unit 1 is vertical to an electric field, broadband isolation can be realized. The antenna can be an antenna array with any linear polarization, and the size of the electromagnetic resonance unit can be properly adjusted based on the working frequency of the antenna.

The specific design method comprises the following steps: selecting a substrate, determining the size of a unit, determining the shape, researching a metamaterial isolator and an antenna coupling mechanism, and preparing the metamaterial-based isolator.

Example 1: (1) selecting a substrate: the material of the printed circuit board with low dielectric loss and low dielectric constant is selected from low-loss dielectric base materials such as teflon, FR4, F4B and the like.

(2) Determining the cell size: determining the total length of the metamaterial structure as one wavelength of an operating frequency band according to the operating frequency of the antenna;

(3) determining the shape: the metamaterial microstructure has more optional figures, such as a triangular shape, a circular shape, a rectangular shape, a rhombic shape and an oval shape, but the figures are different from each other, and a proper figure is selected according to the actual shape of the radome, so that the working area and strength of the metamaterial isolator can meet the expected requirements.

(4) Researching a coupling mechanism of the metamaterial isolator and the antenna: the radiation field of a single antenna can be roughly analyzed through a directional diagram and a field diagram, but the radiation diagram of a plurality of antennas coupled together is complex, and after the metamaterial isolator is added, the radiation diagram has certain influence on the original radiation diagram.

(5) Preparing a metamaterial-based isolator: after the substrate is selected and the patterns and dimensions of the metamaterial structures are determined, the desired metamaterial structures are printed on the printed circuit board material and placed as described in (4).

Because the isolator based on the metamaterial is adopted, the isolation between the antenna pairs is increased only by inhibiting the surface wave in the traditional mode, and the isolation between the antenna pairs is improved in space by adding the metamaterial isolator between the antenna pairs. Because the isolator is based on the metamaterial, the subwavelength characteristic of the isolator enables the original size not to be enlarged after the metamaterial isolator is added between the antenna pairs, and the distance between the antenna pairs can be smaller under the condition of the same isolation degree. By researching the coupling mechanism between the metamaterial isolator and the antenna pair, the parameters of the metamaterial isolator are changed to play a role in improving the isolation between the antenna pair.

As shown in fig. 1, where the corresponding metamaterial structure is a square split ring, where l is 44mm, w is 40mm, d is 1mm, and g is 1mm, when it is placed on the antenna floor between two antennas in fig. 2, and is perpendicular to the direction of the antenna substrate, the antenna isolation is significantly improved as shown in fig. 4.

Claims

1. A broadband antenna isolator based on a metamaterial is characterized in that the broadband antenna isolator is arranged between two antennas and placed on an antenna floor, and when the broadband antenna isolator is perpendicular to the direction of an antenna substrate, the broadband antenna isolator comprises a metamaterial resonance unit (1) and a dielectric substrate (2), wherein the metamaterial resonance unit (1) is printed on the surface of the dielectric substrate (2); the metamaterial resonant unit (1) is in the shape of an open ring, the position of the open ring is arranged at the center of the bottom edge of the ring, the opening direction points to the antenna floor, the total length of the open ring is one wavelength, the width of the open ring is 1mm, and the length of the open ring is 1 mm.

2. The metamaterial-based wideband antenna isolator as claimed in claim 1, wherein the split ring is triangular, circular, rectangular, diamond-shaped or oval in shape.

3. A metamaterial based wideband antenna isolator as claimed in claim 1, wherein the metamaterial resonant unit (1) is a metal material.

4. A metamaterial based wideband antenna isolator as claimed in claim 1, wherein the dielectric substrate (2) is teflon, FR4 or F4B.