CN103414029A - Rectangular frame fractal antenna with both near-zero refractive index effect and left-handed effect - Google Patents

Abstract

The invention relates to a rectangular frame fractal antenna based on the left-hand material of a rectangular split ring. The patch antenna includes a three-layer dielectric substrate, a metal ground plate, a rectangular frame fractal metal radiation sheet, a microstrip feeder, and a rectangular metal resonant ring. The dielectric substrate of the composite structure has three layers, the relative permittivity of the first and third layers is 10, and the relative permittivity of the second layer is 2.2. The excitation source adopts Gaussian discrete source, and feeds the patch antenna through the microstrip feeder. In the invention, the antenna formed by adding a rectangular split ring left-handed material to the fractal structure of a rectangular frame has a left-handed effect and a near-zero refractive index effect at different frequencies, which significantly improves the localization degree of electromagnetic energy and improves the beam Convergence is generated, resulting in a significant increase in antenna gain, and a lower return loss, which improves the performance of the antenna and can be widely used in mobile communications, satellite communications, aerospace and other fields.

Description

A Rectangular Frame Fractal Antenna with Near-Zero Refractive Index Effect and Left-Handed Effect Simultaneously

technical field

The invention belongs to the technical field of communication, and in particular relates to a rectangular frame fractal antenna based on a rectangular split ring left-hand material.

Background technique

Recently, as another branch of artificial electromagnetic metamaterials, the research on zero-refractive-index metamaterials has attracted widespread attention. Many teams have confirmed the existence of zero-refractive materials and near-zero-refractive materials through experiments. For the first time, ENOCH and others confirmed that when the radiation source is embedded in a zero-refractive-index substrate, the energy of the radiation will be confined in a narrow conical region of the surrounding medium, that is, by utilizing the characteristics of the zero-refractive-index material, the direction of energy radiation Sex has been greatly improved.

The concept of fractal was first proposed by a French mathematician named Mandelbrot in 1983 in the book "Fractal Geometry in Nature". Fractal geometry is the geometry of self-similar graphics and structures that are infinitely complex and have specific meanings. Self-similarity is the similarity between the local shape and the overall shape. The so-called fractal antenna refers to an antenna with fractal geometric characteristics in terms of geometric properties. It is a new type of antenna designed by combining antenna design theory with fractal geometry. The self-filling characteristic of fractal geometry makes it easier to miniaturize the antenna unit. On the other hand, due to the self-similarity characteristic of fractal geometry, the antenna can obtain multi-band characteristics.

Left-handed material (LHM) is a new type of artificial electromagnetic medium with periodic structure. Its permittivity and magnetic permeability are negative at the same time. Therefore, when the electromagnetic wave propagates in this double negative dielectric material, the electric vector, magnetic The three vectors and wave vectors satisfy the left-hand rule, so they are called left-handed materials (or negative refraction materials). As a new type of artificial electromagnetic material, it has aroused great research interest. As early as 1968, V.G. Veselageo theoretically studied the abnormal electromagnetic phenomena in LHM; in 2000, Smith et al. discovered for the first time that a composite medium with a special microstructure periodically arranged can simultaneously obtain negative dielectric constant and negative The magnetic permeability, thus experimentally verified that this material can be prepared by artificial methods. The anomalous electromagnetic special of LHM makes it have important application value in the fields of light and electromagnetic waves.

The present invention obtains the corresponding performance parameters through the research of a rectangular frame fractal antenna system based on the left-hand material of the rectangular split ring, and uses the Nicolson-Ross-Weir (NRW) method to calculate the equivalent of the fractal antenna based on the rectangular frame left-hand material. refractive index.

Contents of the invention

The technical problem to be solved by the present invention is to provide a left-handed material rectangular frame fractal antenna with near-zero refractive index effect and left-handed effect at the same time. The degree of energy localization reduces the return loss of the antenna and increases the gain; at the same time, in another frequency range, it has a near-zero refractive index effect, which further improves the directional gain of the antenna.

In order to solve the above technical problems, a rectangular frame fractal antenna based on a rectangular split ring left-handed material of the present invention includes a first layer of dielectric substrate 1, a second layer of dielectric substrate 2, a third layer of dielectric substrate 3, a metal ground plate 4, micro Belt feeder 5, rectangular frame fractal metal radiation patch 6, rectangular metal resonant ring 7. The first layer of dielectric substrate 1, the second layer of dielectric substrate 2, the third layer of dielectric substrate 3, and the metal ground plate 4 are stacked in sequence. The left-hand material fractal antenna with a rectangular frame is composed of a rectangular frame fractal metal radiation patch 6 and a microstrip feeder 5. The microstrip feeder 5 is connected to the excitation source through a metal wire, and is used to feed the rectangular frame fractal antenna based on the left-hand material of the rectangular split ring. The front surfaces of the first dielectric substrate 1 , the second dielectric substrate 2 and the third dielectric substrate 3 all adopt circuit board etching technology. The front of the first layer of dielectric substrate 1 adopts circuit board etching technology to etch a rectangular frame fractal patch antenna and periodically arranged rectangular metal resonant rings 7; the front of the second layer of dielectric substrate 2 and the third layer of dielectric substrate 3 are both Rectangular metal resonant rings 7 arranged periodically are etched out by circuit board etching technology, and a metal ground plate 4 is pasted on the reverse side of the third dielectric substrate 3, which is connected to the excitation source through metal wires.

A total of 36 rectangular metal resonant rings 7 are periodically arranged on the front side of the third layer of dielectric substrate 3, and are evenly arranged in a 6×6 structure. The second layer of dielectric substrate 2 is in phase with the third layer of dielectric substrate 3 Compared with the front, except for the lack of four rectangular metal resonant rings 7 in the middle, the arrangement is the same as that of the third layer of dielectric substrate 3, and a total of 32 rectangular metal resonant rings 7 are arranged. The front of the first layer of dielectric substrate 1 The arrangement of the rectangular metal resonant rings 7 is the same as that of the rectangular metal resonant rings 7 on the front of the second dielectric substrate 2, and a rectangular frame fractal patch antenna is etched in the center by circuit board etching technology.

The composition structure of the rectangular frame fractal antenna based on the left-handed material of the rectangular split ring can be selected as follows: the size of the first layer of dielectric substrate 1, the second layer of dielectric substrate 2, and the third layer of dielectric substrate 3 is 80mm×80mm ×7mm; the first layer of dielectric substrate 1, the second layer of dielectric substrate 2 and the third layer of dielectric substrate 3 have the same size, and the length and width are both 80mm×80mm; the first layer of dielectric substrate 1 and the third layer of dielectric substrate 3 The relative permittivity is 10, the thickness is D ₁ =2mm, the relative permittivity of the second layer of dielectric substrate 2 is 2.2, and the thickness is D ₂ =3mm; the front of the first layer of dielectric substrate 1 is fixed with a width W ₇ = 27mm rectangular frame fractal metal radiation patch 6, wherein the rectangular frame fractal metal radiation patch 6 is composed of 25 rectangular frames whose length and width are both W ₈ =3mm; the rectangular metal resonant ring 7 consists of two layers of rectangular split rings inside and outside Composition, the length and width of the outer rectangular split ring are both W ₂ =9mm, the length and width of the inner rectangular split ring are both W ₃ =7mm, the width of the rectangular metal resonant ring 7 is W ₉ =0.5mm, and the inner and outer rectangular openings The widths are all W ₅ =1 mm, the left and right intervals of adjacent rectangular metal resonant rings 7 are S ₁ =4 mm, and the upper and lower intervals are also S ₁ =4 mm. The distance W ₄ between the rectangular metal resonant ring 7 and the edge of the dielectric substrate is 3mm. The length L ₂ =38.5 mm and the width W ₆ =1 mm of the microstrip feeder 5 . The reverse side of the dielectric substrate 3 of the third layer is attached with an 80mm×80mm metal grounding plate 4. One end of the excitation source is connected to the microstrip feeder 5 through a metal wire, and the other end is connected to the metal grounding plate 4. The excitation source adopts a Gaussian discrete source and passes through the microstrip feeder 5 Feed power to the rectangular frame fractal metal radiator 6.

In order to verify the effectiveness of the present invention, the above-mentioned rectangular frame fractal antenna structure based on the left-hand material of the rectangular split ring is tested by the simulation software XFDTD, which is based on the electromagnetic numerical calculation method FDTD (finite difference method in time domain) developed by the U.S. REMCOM company The full-wave 3D electromagnetic simulation software has high reliability of simulation results. Through the simulation test of the software, the performance parameter values corresponding to the antenna performance can be obtained, such as return loss (s11, also known as reflection coefficient), transmission coefficient (s21), voltage standing wave ratio (VSWR) and gain (Gain), etc. . By analyzing these values, you can compare the pros and cons of the antenna performance.

The present invention forms a rectangular frame fractal antenna based on the left-hand material of the rectangular split ring by adding the left-hand material structure of the rectangular split ring to the ordinary rectangular frame fractal antenna. Comparing the effect of the antenna at two frequencies, it is found that the left-hand effect has a smaller return loss, and the near-zero refractive index effect has a higher directional gain; and the rectangular frame fractal antenna with a rectangular resonant ring is compared with the ordinary rectangular Compared with the frame fractal antenna, it is found that it has smaller return loss and higher gain than the latter. From a theoretical point of view, the reasons are as follows: On the one hand, the resonance state of electromagnetic waves generated at the frequency of f=15.9098GHz makes the overall relative permittivity and permeability of the structure negative, forming a "tunnel" effect of electromagnetic waves And the amplification effect of the evanescent wave, thereby greatly enhancing the electromagnetic wave resonance intensity. On the other hand, at f=23.2309GHz, the near-zero refractive index effect produces a converging effect on the electromagnetic beam, resulting in a significant increase in antenna gain, which is manifested as a lower return loss, which improves the performance of the antenna.

Description of drawings

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

Fig. 1 is a schematic diagram of the front structure of a rectangular frame fractal antenna based on a rectangular split ring left-hand material according to the present invention, wherein: 1-the first layer of dielectric substrate; 2-the second layer of dielectric substrate; 3-the third layer of dielectric substrate; 4- Metal ground plate; 5-microstrip feeder; 6-fractal metal radiation patch with rectangular frame; 7-rectangular metal resonant ring.

Fig. 2 is a schematic structural diagram of a second-layer dielectric substrate of a rectangular frame fractal antenna based on a rectangular split ring left-handed material in the present invention;

Fig. 3 is a schematic structural diagram of a third-layer dielectric substrate of a rectangular frame fractal antenna based on a rectangular split ring left-hand material according to the present invention;

Fig. 4 is a schematic diagram of the structure of a rectangular metal resonant ring of a rectangular frame fractal antenna based on a rectangular split ring left-hand material of the present invention;

Fig. 5 is a schematic diagram of the structure combination of each layer of a rectangular frame fractal antenna based on a rectangular split ring left-hand material according to the present invention;

Fig. 6 is the relative permittivity, magnetic permeability and refractive index n of a kind of rectangular frame fractal antenna overall structure based on rectangular split ring left-hand material of the present invention, wherein (a) the rectangular frame fractal antenna that is embedded with resonant ring is at f= Refractive index n at 23.2309Ghz, magnetic permeability μ _r , dielectric constant ε _r ; (b) Refractive index n at f=15.9098Ghz, magnetic permeability μ r , dielectric constant _{ε r} of a rectangular frame fractal antenna embedded with a resonant ring Electrical constant ε _r ;

Fig. 7 is a schematic diagram of the return loss s11 of a rectangular frame fractal antenna based on the left-hand material of a rectangular split ring according to the present invention, wherein (a) s11 of the rectangular frame fractal antenna embedded with a resonant ring at a frequency f=23.2309GHz; (b) The s11 of the rectangular frame fractal antenna embedded with resonant ring at frequency f=15.9098GHz;

Fig. 8 is a schematic diagram of voltage standing wave ratio VSWR of a rectangular frame fractal antenna based on a rectangular split ring left-hand material in the present invention, wherein (a) the VSWR of the rectangular frame fractal antenna embedded with a resonant ring at frequency f=23.2309GHz; (b ) VSWR of a rectangular frame fractal antenna with a resonant ring embedded at frequency f=15.9098GHz;

Fig. 9 is a schematic diagram of the gain of a rectangular frame fractal antenna based on a rectangular split ring left-handed material in the present invention, wherein (a) the gain polarization diagram of the rectangular frame fractal antenna embedded with a resonant ring at a frequency f=23.2309GHz; (b) The gain polarization diagram of the rectangular frame fractal antenna embedded with resonant ring at frequency f=15.9098GHz.

specific implementation plan

Using circuit board etching technology, as shown in Figure 1, the rectangular frame fractal antenna 6 and rectangular metal resonant ring are etched on the first layer of dielectric substrate 1 based on the near-zero refractive index left-handed material patch antenna structure. 7. 32 rectangular metal resonance rings 7 are periodically etched on the second dielectric substrate 2 , and 36 rectangular metal resonance rings 7 are periodically arranged on the third dielectric substrate 3 . The microstrip feeder 5 is connected to the rectangular frame fractal metal radiator 6 as the feed source of the electric wave signal.

The present invention is a rectangular frame fractal antenna based on the left-hand material of the rectangular split ring. As shown in Figure 1, the fractal antenna of the left-hand material of the rectangular frame has three layers of dielectric substrates with the same size, and the superimposed size is 80mm×80mm× 7mm. The relative permittivity of the first dielectric substrate 1 and the third dielectric substrate 3 is 10, and the thickness D ₁ =2mm. The relative permittivity of the second dielectric substrate 2 is 2.2, and the thickness D ₂ =2mm.

The size of the first layer of dielectric substrate 1, the second layer of dielectric substrate 2, and the third layer of dielectric substrate 3 is 80mm×80mm×7mm; the first layer of dielectric substrate 1, the second layer of dielectric substrate 2 and the third layer of dielectric substrate 3 have the same size, the length and width are both 80mm×80mm; the relative permittivity of the first layer of dielectric substrate 1 and the third layer of dielectric substrate 3 are both 10, and the thickness is D ₁ =2mm, and the second layer of dielectric substrate 2 The relative permittivity of each is 2.2, and the thickness D ₂ =3mm; the front of the first dielectric substrate 1 is fixed with a rectangular frame fractal metal radiation patch 6 with a width W ₇ =27mm, wherein the rectangular frame fractal metal radiation patch 6 consists of 25 It is composed of a rectangular frame whose length and width are both W ₈ =3 mm; 32 rectangular metal resonant rings 7 are embedded on the first dielectric substrate 1, and the rectangular metal resonant ring 7 is composed of two inner and outer rectangular split rings, and the outer rectangular split ring The length and width are both W ₂ =9mm, the length and width of the inner rectangular opening ring are both W ₃ =7mm, the width of the rectangular metal resonant ring 7 is W ₉ =0.5mm, and the opening width of the inner and outer rectangles is W ₅ =1mm , the adjacent rectangular metal resonant rings 7 have a left and right interval of S ₁ =4 mm, and an upper and lower interval of S ₁ =4 mm. The distance W ₄ between the rectangular metal resonant ring 7 and the edge of the dielectric substrate is 3mm. The length L ₂ =38.5 mm and the width W ₆ =1 mm of the microstrip feeder 5 . 32 rectangular metal vibration rings 7 are periodically arranged on the second dielectric substrate 2 , and 36 rectangular metal resonance rings 7 are periodically arranged on the third dielectric substrate 3 . The reverse side of the dielectric substrate 3 of the third layer is attached with an 80mm×80mm metal grounding plate 4. One end of the excitation source is connected to the microstrip feeder 5 through a metal wire, and the other end is connected to the metal grounding plate 4. The excitation source adopts a Gaussian discrete source and passes through the microstrip feeder 5 Feed power to the rectangular frame fractal metal radiator 6.

In order to verify whether the designed structure has the near-zero refractive index effect and the left-hand effect, the XFDTD electromagnetic simulation software is used to simulate the rectangular frame fractal antenna based on the rectangular split ring left-hand material, and the overall scattering parameters of the structure are obtained, that is, the reflection Coefficient (s11) and transmission coefficient (s21), through the NRW transmission/reflection algorithm, the effective permittivity and effective permeability electromagnetic parameters of the composite structure are extracted. Figure 4 shows the parameters extracted from the simulation The effective permeability μ _r , effective permittivity ε _r and refractive index n of the composite structure. At the frequency of f=23.2309GHZ near the antenna resonance point, the overall refractive index of the antenna dielectric plate is less than zero and close to zero, where the effective permeability μ _r =-0.156, the effective permittivity ε _r =-0.3107, which is equivalent to Refractive index n=-0.2201, its value is close to zero. In the vicinity of the resonance point f=15.9098Ghz, the effective permeability μ _r =-0.5009, the effective permittivity ε _r =-2.406, and the equivalent refractive index n=-1.098, which are non-near zero. As shown in Figure 5, the return loss s11 characteristic diagram of the rectangular frame fractal antenna based on the left-hand material of the rectangular split ring, the minimum return loss s11=-31.6528dB at the frequency f=23.2309GHZ, and the resonance point f=15.9098 Near Ghz, the minimum return loss s11=-37.8794dB, indicating that the left-hand effect has a smaller return loss.

Figure 6 shows the VSWR characteristic diagram. At the frequency f=23.2309GHZ, the minimum VSWR is 1.05, which is very close to the ideal value of 1. Near the resonance point f=15.9098Ghz, the minimum VSWR is 1.026.

Figure 7 shows the gain characteristic diagram. After adding the left-handed material structure of the rectangular metal resonant ring, this multilayer composite left-handed material rectangular frame fractal antenna has a maximum forward gain of about 10.8dB at the frequency f=23.2309GHZ, and at the resonance point The maximum positive gain near f=15.9098Ghz is 6.3dB. It shows that the near-zero refractive index effect has higher directional gain.

Through the study of the rectangular frame fractal antenna based on the left-handed material of the rectangular split ring, it is found that its characteristic is that the antenna has a left-handed effect and a near-zero refractive index effect. Comparing the effects of the antenna at two frequencies, it is found that the left-handed effect has Smaller return loss, and the near-zero refractive index effect has higher directional gain; and compared the rectangular frame fractal antenna with the rectangular resonant ring with the ordinary rectangular frame fractal antenna, it is found that it has a smaller return loss and higher gain. From a theoretical point of view, the reasons are as follows: on the one hand, after the left-handed material is added to the base medium of the patch antenna, an electromagnetic (photonic) forbidden band will be formed, which will suppress the surface wave propagating along the base plate medium, thereby increasing the direction of electromagnetic waves. The reflected energy of free space; on the other hand, the electromagnetic wave resonance state generated at f=15.9098GHz frequency makes the overall relative permittivity and magnetic permeability of the structure both negative, forming the "tunnel" effect and evanescence of electromagnetic waves The amplification effect of the evanescent wave greatly enhances the resonance intensity of the electromagnetic wave. In addition, at f=23.2309GHz, the near-zero refractive index effect has a converging effect on the electromagnetic beam, resulting in a significant increase in the antenna gain and a lower echo Loss, better to improve the performance of the antenna.

So far, the fabrication of the fractal antenna based on the left-hand material of the rectangular frame has been completed.

Claims (3)

1. A rectangular frame fractal antenna based on the left-hand material of a rectangular split ring, characterized in that it includes a first layer of dielectric substrate (1), a second layer of dielectric substrate (2), a third layer of dielectric substrate (3), a metal junction Floor (4), microstrip feeder (5), rectangular frame fractal metal radiation patch (6), rectangular metal resonant ring (7); the first layer of dielectric substrate (1), the second layer of dielectric substrate (2), the second The three-layer dielectric substrate (3) and the metal grounding plate (4) are stacked in sequence, and the rectangular frame fractal patch antenna is composed of a rectangular frame fractal metal radiation patch (6) and a microstrip feeder (5), and the microstrip feeder (5) passes through The metal wire is connected to the excitation source, and is used to feed the rectangular frame fractal antenna based on the left-hand material of the rectangular split ring; the front side of the first layer of dielectric substrate (1) is etched with a circuit board etching technology to form a rectangular frame fractal patch antenna and Periodically arranged rectangular metal resonant rings (7), the front surfaces of the second layer of dielectric substrate (2) and the third layer of dielectric substrate (3) are all etched out of periodically arranged rectangular metal resonant rings ( 7), the reverse side of the third dielectric substrate (3) is pasted with a metal grounding plate (4), which is connected to the excitation source through metal wires. 2. A rectangular frame fractal antenna based on a rectangular split ring left-handed material according to claim 1, characterized in that: the rectangular metal resonant ring (7) periodically arranged on the front of the third dielectric substrate (3) A total of 36 pieces are evenly arranged in a 6×6 structure. Compared with the third layer dielectric substrate (3), the second layer of dielectric substrate (2) lacks four rectangular metal resonant rings ( 7) The other arrangement is the same as that of the third layer of dielectric substrate (3), a total of 32 rectangular metal resonant rings (7) are arranged, and the rectangular metal resonant ring (7) on the front side of the first layer of dielectric substrate (1) ) is arranged in the same arrangement as the rectangular metal resonant ring (7) on the front of the second dielectric substrate (2), and a rectangular frame fractal patch antenna is etched in the center by using circuit board etching technology. 3. A rectangular frame fractal antenna based on a rectangular split ring left-handed material according to claim 1 or 2, characterized in that: the first layer of dielectric substrate (1), the second layer of dielectric substrate (2), the third layer The size of the stacked dielectric substrates (3) is 80mm×80mm×7mm; the dimensions of the first layer of dielectric substrate (1), the second layer of dielectric substrate (2) and the third layer of dielectric substrate (3) are the same, with the same length and width. The relative permittivity of the first layer of dielectric substrate (1) and the third layer of dielectric substrate (3) are both 10, and the thickness is D ₁ =2mm, the relative permittivity of the second layer of dielectric substrate (2) Both are 2.2, thickness D ₂ =3mm; the front of the first dielectric substrate (1) is fixed with a rectangular frame fractal metal radiation patch (6) with a width W ₇ =27mm, in which the rectangular frame fractal metal radiation patch (6) consists of 25 A rectangular frame whose length and width are both W ₈ =3 mm; the rectangular metal resonant ring (7) is composed of two inner and outer rectangular split rings, the outer rectangular split ring has a length and width of W ₂ =9 mm, and the inner The length and width of the layered rectangular opening ring are both W ₃ =7mm, the width of the rectangular metal resonant ring (7) is W ₉ =0.5mm, the opening width of the inner and outer rectangles is both W ₅ =1mm, and the adjacent rectangular metal resonant ring ( 7) The distance between left and right is S ₁ =4mm, the distance between top and bottom is also S ₁ =4mm, the distance between the rectangular metal resonant ring (7) and the edge of the dielectric substrate is W ₄ =3mm, the length L ₂ of the microstrip feeder (5) =38.5mm, and the width W ₆ =1mm, 80mm×80mm metal grounding plate (4) is pasted on the reverse side of the third dielectric substrate (3), the excitation source is connected to the microstrip feeder (5) through a metal wire at one end, and the metal grounding plate (4) at one end , the excitation source adopts a Gaussian discrete source, and feeds the rectangular frame fractal metal radiator (6) through the microstrip feeder (5).

Images