Multi-band miniaturized antenna based on new metamaterial unit loading

Abstract

The present invention discloses a multi-band miniaturized antenna based on a novel metamaterial unit, belonging to the field of wireless communication, comprising a symmetrical annular metal left-handed material unit, a coplanar waveguide feeding structure, a dielectric substrate, a metal feed line and a metal cross bar; the symmetrical annular metal left-handed material unit, the metal cross bar and the metal feed line are located on the upper surface of the dielectric substrate, wherein one end of the metal feed line is connected to the annular metal left-handed material unit, and the metal cross bar is connected to the metal feed line; the coplanar waveguide feeding structure is divided into two parts located on the upper and lower surfaces of the dielectric substrate, wherein the part located on the upper surface is a planar metal plate loaded on both sides of the metal feed line, both of which maintain a gap with the metal feed line. The present invention applies a multi-band left-handed material unit to antenna design, and by performing phase compensation on the electromagnetic waves thereon, breaks through the size limit of half a wavelength of a traditional microstrip antenna, and greatly reduces the size of the antenna without changing the omnidirectional radiation characteristics of the antenna itself.

Description

Technical Field

[0001] The present invention belongs to the field of wireless communications, and in particular relates to a multi-band miniaturized antenna based on novel metamaterial unit loading. Background Art

[0002] In recent years, with the rapid development of communication technology, intelligent communication equipment and systematization are increasingly moving towards multi-functionality, miniaturization, and even miniaturization. Antennas, as communication equipment and their important components, are responsible for sending and receiving signals. With the miniaturization of communication equipment, the volume space reserved for antennas when designing equipment will become smaller and smaller, but the functional requirements for antennas are increasing. Therefore, traditional antennas are no longer able to meet the many requirements of communication equipment at this stage, and the miniaturization and multi-band technology of antennas are in urgent need of development. The multi-band antenna means that communication equipment can work in different frequency bands; and the miniaturization technology of antennas can greatly reduce the size of the antenna, so that the antenna occupies a smaller space inside the device, providing more possibilities for the device to integrate other functions. Therefore, antennas with miniaturization and multi-band characteristics are more suitable for the needs of modern equipment. Therefore, the research and development of new miniaturized and multi-band 5G antennas has high industrial practical value.

[0003] At present, there are many methods to achieve miniaturization and multi-band, which are also reflected in the patents in recent years, such as adding bent metal wires to increase the current path, adding metal probes, using meta-structure materials, etc. to achieve antenna miniaturization; by adding new branches, using multi-layer antennas, etc. to achieve antenna multi-band. For example, in patent CN113517566A, the method of adding meta-structure materials is used to achieve miniaturization, but the size of the antenna is still large, which is not conducive to use in production; in patent CN217134672, multiple etching lines are used to simulate the multi-branch effect to achieve multi-band, but the antenna has a split radiation pattern in the third frequency band; in patent CN113555682A, the stacking technology of the antenna and multi-branch are used at the same time to achieve three frequency bands. However, due to the quality factor of the antenna, the size of the antenna cannot be further reduced; at the same time, the complexity of the antenna will increase accordingly when using the multi-branch method to achieve multi-band, which is not easy to manufacture; using the method of stacking multi-layer antennas together, the coupling between the antennas of each layer will also increase, and it is not easy to control the frequency bands of the antenna. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention provides a multi-band miniaturized antenna based on a new metamaterial unit, and applies the multi-band left-handed material unit to the antenna design. By utilizing the unique backward wave transmission characteristics of the left-handed material unit and performing phase compensation on the electromagnetic waves thereon, the half-wavelength size limitation of the traditional microstrip antenna can be broken, and the size of the antenna can be greatly reduced without changing the omnidirectional radiation characteristics of the antenna itself.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0006] A multi-band miniaturized antenna based on a novel metamaterial unit comprises a symmetrical annular metal left-handed material unit, a coplanar waveguide feeding structure, a dielectric substrate, a metal feed line and a metal horizontal bar located directly below the symmetrical annular metal left-handed material unit; the symmetrical annular metal left-handed material unit, the metal horizontal bar and the metal feed line are located on the upper surface of the dielectric substrate, wherein the metal feed line is subordinate to the coplanar waveguide feeding structure, one end of which is connected to the symmetrical annular metal left-handed material unit, the metal horizontal bar is connected to the metal feed line, and when current flows through the metal horizontal bar, a new current path is formed, thereby adding a new resonance point to the antenna; the coplanar waveguide feeding structure is divided into two parts located on the upper and lower surfaces of the dielectric substrate, wherein the part located on the upper surface of the dielectric substrate is a planar metal plate loaded on both sides of the metal feed line and maintaining a gap with the metal feed line, and the part located on the lower surface of the dielectric substrate is a metal ground plate symmetrical to the upper surface, and the width of the metal ground plate is the same as that of the dielectric substrate.

[0007] Since the size of the left-handed material is much smaller than the wavelength of its resonant frequency in free space, the left-handed material unit, which has multi-band characteristics, is used as the radiating part of the antenna. The multi-band characteristics of the left-handed material unit itself can be used to realize the multi-band of the antenna, and the unique transmission properties of the left-handed material itself can be used to realize the miniaturization of the antenna without being restricted by the half-wavelength limit of the traditional antenna. The present invention adds a metal horizontal bar under the left-handed material unit to broaden the bandwidth of the antenna with the left-handed material unit as the radiating part, which can provide good matching for the high frequency band on the one hand; at the same time, the metal horizontal bar is connected to the metal feeder, and the current flowing through the metal bar will form a new current path, which can add a new resonance point to the antenna, and the new resonance point does not overlap with the original frequency band, thereby expanding the available frequency bandwidth of the antenna.

[0008] The symmetrical annular metal left-handed material unit is composed of two symmetrically distributed semicircular metal rings, and there is a gap between the two semicircular metal rings, wherein each semicircular metal ring is provided with a truncation at the top, a gap is cut out, and a pair of symmetrical metal wires are added inward at the gap, and there is a gap between the symmetrical metal wires. By adjusting the distance between the symmetrical metal wires in the two semicircular metal rings, the size of the coupling capacitor can be adjusted, thereby changing the resonant frequency of the antenna; the line widths of each part in the symmetrical annular metal left-handed material unit are the same. The symmetrical annular metal left-handed material unit is annular as a whole. When the magnetic field component of the incident electromagnetic wave is perpendicular to the annular unit, a circular current similar to a magnetic monopole can be generated, so that it constitutes a magnetic resonator, so that the structure has a negative equivalent magnetic permeability; at the same time, the two B-type structures formed in the symmetrical annular metal left-handed material unit, when the electric field of the incident electromagnetic wave is parallel to the annular unit, two symmetrical current loops will be generated, thereby constituting a symmetrical electric resonator, and a negative dielectric constant will be generated in the resonance area.

[0009] The metal feed line belongs to a coplanar waveguide feeding structure, and the input impedance is 50 ohms.

[0010] The lower end of the metal feeder is welded with an SMA interface for testing.

[0011] Preferably, the distance between the structural center of the symmetrical annular metal left-handed material unit and the annular line is R =5.8mm, line width of symmetrical ring-shaped metal left-handed material unit W r=0.4mm, the length of the symmetrical metal wire in the symmetrical ring metal left-handed material unit Lr =4.5mm, there is a gap between the symmetrical metal wires Gr =0.5mm.

[0012] Preferably, the length of the metal bar L 1=12.5mm, width W 1=0.5mm; the width of the metal feeder W 2 = 1 mm, when the metal bar is connected to the metal feeder, the distance between the end of the metal feeder connected to the symmetrical annular metal left-handed material unit and the metal bar L 3=1mm, the vertical distance between the other end and the metal bar L 2=10.5mm.

[0013] Preferably, the length of the planar metal plate in the coplanar waveguide feeding structure is L 0 = 8.5mm, width W 0=8.5mm; size is 23×14×0.8mm 3The dielectric substrate is an FR4 epoxy resin board with a dielectric constant of 4.4, a relative magnetic permeability of 1.0, and a loss tangent of 0.002.

[0014] Preferably, the metal materials involved in the symmetrical annular metal left-handed material unit, the metal horizontal bar, the coplanar waveguide feeding structure, and the metal feed line are all copper.

[0015] The technical solution of the present invention can produce the following technical effects:

[0016] The multi-band miniaturized antenna based on the novel metamaterial unit loading described in the present invention applies the multi-band left-handed material unit to the antenna design, utilizes the unique backward wave transmission characteristics of the left-handed material unit to perform phase compensation on the electromagnetic wave, can break through the half-wavelength size limit of the traditional microstrip antenna, thereby realizing the miniaturization of the antenna; while realizing the miniaturization, the omnidirectional radiation characteristics of the antenna itself are not changed, and the size of the antenna is only 0.185λ×0.113λ, wherein λ is the wavelength of the first resonant frequency point, which greatly reduces the size of the antenna; at the same time, relying on the multi-band characteristics of the left-handed material unit in the present invention, the antenna forms multiple frequency bands: 2.40-2.44GHz, 4.38-5.16GHz and 5.61-6.22GHz, and the antenna can be applied to multiple commercial bands such as WLAN band, WiMax band, N79 band, and can maintain the omnidirectional radiation characteristics in each resonant frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a multi-band miniaturized antenna based on a novel metamaterial unit provided by the present invention;

[0018] Figure 2 A front view of a multi-band miniaturized antenna based on a novel metamaterial unit provided by the present invention and a schematic diagram of its parameters;

[0019] Figure 3 A back view of a multi-band miniaturized antenna based on a novel metamaterial unit provided by the present invention and a schematic diagram of its parameters;

[0020] Figure 4 The return loss diagram of the multi-band miniaturized antenna based on the novel metamaterial unit loading provided by the present invention;

[0021] Figure 5 A schematic diagram of the standing wave ratio of the multi-band miniaturized antenna based on the novel metamaterial unit provided by the present invention in each resonant frequency band;

[0022] Figure 6 The three-dimensional radiation pattern of the multi-band miniaturized antenna based on the novel metamaterial unit loading provided by the present invention at 2.41 GHz;

[0023] Figure 7 The E-plane and H-plane radiation patterns of the multi-band miniaturized antenna based on the novel metamaterial unit loading provided by the present invention at 2.41 GHz;

[0024] Figure 8 The three-dimensional radiation pattern of the multi-band miniaturized antenna based on the novel metamaterial unit loading provided by the present invention at 4.79 GHz;

[0025] Fig. 9 The E-plane and H-plane radiation patterns of the multi-band miniaturized antenna based on the novel metamaterial unit loading provided by the present invention at 4.79 GHz;

[0026] Fig.10 The three-dimensional radiation pattern of the multi-band miniaturized antenna based on the novel metamaterial unit loading provided by the present invention at 5.73 GHz;

[0027] Fig.11 The E-plane and H-plane radiation patterns of the multi-band miniaturized antenna based on the novel metamaterial unit loading provided by the present invention at 5.73 GHz;

[0028] Fig.12 The radiation efficiency and peak gain diagram of the multi-band miniaturized antenna loaded with a novel metamaterial unit provided by the present invention in each resonant frequency band.

[0029] Reference numerals: symmetrical annular metal left-handed material unit 1; metal horizontal bar 2; coplanar waveguide feeding structure 3; dielectric substrate 4; metal feed line 5; SMA interface 6. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0031] In this embodiment, Figure 1 The figure shows the overall structure of the multi-band miniaturized antenna based on the novel metamaterial unit loading according to the present invention. Figure 2 This is the front view of the antenna and a schematic diagram of its specific parameters. Figure 3The back side of the antenna and the schematic diagram of its specific parameters. The multi-band miniaturized antenna based on the novel metamaterial unit loading of the present invention comprises a symmetrical annular metal left-handed material unit 1, a coplanar waveguide feeding structure 3, a dielectric substrate 4, a metal feed line 5, an SMA interface 6 and a metal horizontal bar 2 located directly below the symmetrical annular metal left-handed material unit 1. The upper surface of the dielectric substrate 4 is the radiation part of the antenna, including a symmetrical annular metal left-handed material unit 1, a metal feed line 5, and a metal horizontal bar 2 for improving matching and expanding bandwidth, wherein one end of the metal feed line 5 is connected to the symmetrical annular metal left-handed material unit 1, and the metal feed line 5 vertically passes through the metal horizontal bar 2 downward, and when the current flows through the metal horizontal bar 2, a new current path is formed, thereby adding a new resonance point to the antenna; the lower surface of the dielectric substrate 4 is a part of the coplanar waveguide feeding structure 3, which together with the symmetrical upper surface constitutes a complete back-copper-clad coplanar waveguide feeding structure 3, wherein the part of the coplanar waveguide feeding structure 3 on the upper surface of the dielectric substrate 4 is located on both sides of the metal feed line 5, and maintains a certain gap with the metal feed line 5.

[0032] The size of the dielectric substrate 4 used in this example is L s× W s, with a thickness of 0.8mm, and an overall rectangular shape. Its material is an FR4 epoxy resin board with a dielectric constant of 4.4, a relative magnetic permeability of 1.0, and a loss tangent of 0.002. At the same time, copper is applied on its surface to form the antenna radiation part.

[0033] The symmetrical annular metal left-handed material unit 1 is composed of two symmetrically distributed semicircular metal rings, and there is a certain gap between the two semicircular metal rings, wherein the top of each semicircular metal ring is cut off to form a notch, and a pair of symmetrical metal wires are added inwardly at the notch, with a length of Lr , there is a gap between the symmetrical metal lines Gr , which can be used to realize the coupling capacitor part of the resonant structure. By adjusting the distance between the symmetrical metal lines, the size of the coupling capacitor can be adjusted, thereby changing the resonant frequency of the antenna; the line width of each part in the symmetrical annular metal left-handed material unit 1 is the same, and the width is W r, the distance from the center of the unit structure to the ring line is R .

[0034] The parameters of each part were optimized by electromagnetic simulation software, and the optimal dimensions of each part are as follows: The length of the dielectric substrate L s=23mm, width W s is 14 mm. The length of the metal copper of the coplanar waveguide feeding structure on the upper surface of the dielectric substrate L 0 = 8.5mm, width W0=8.5mm, and the structures on both sides of the metal feeder are exactly the same; the width of the structure on the back of the dielectric substrate is the same as the width of the dielectric substrate. W s=14mm. Related parameters of microstrip metal feed line, width W 2=1mm, L 2=10.5mm, L 3=1mm. Width of the metal strip W 1=0.5mm, length L 1=12.5mm. Parameters related to left-hand unit W r=0.4mm, R =5.8mm, L r=4.5mm, G r=0.5mm.

[0035] In addition, the thickness of the copper cladding used in the present invention is 0.03 mm.

[0036] In the relevant electromagnetic simulation software, the antenna is simulated and calculated using the above optimal parameters to obtain the antenna's S parameter curve, antenna standing wave ratio curve, radiation pattern at each resonant frequency point, and the antenna's radiation efficiency and gain curve.

[0037] Figure 4 The figure shows the S parameter diagram of the antenna. It can be seen from the figure that the antenna's available operating frequency band (i.e. | S 11|<-10dB) has three parts, namely 2.40~2.44GHz, 4.38~5.16GHz, 5.61~6.22GHz, and the center frequencies are 2.41GHz, 4.79GHz, and 5.73GHz. Figure 5 It can be seen from the standing wave ratio curve that the standing wave ratio of the antenna in each resonant frequency band is less than 2, indicating that the antenna is well matched in each resonant frequency band.

[0038] Figures 6 to 11 They are the two-dimensional radiation pattern and three-dimensional radiation pattern of the center frequency of each resonant frequency band. From the two-dimensional H-plane radiation pattern, it can be seen that the radiation pattern of the antenna at each resonant frequency point is approximately circular, so the antenna maintains an omnidirectional radiation pattern in each resonant frequency band, and it is very stable, without the situation of pattern splitting. Moreover, the radiation room pattern of the antenna is the same as the radiation pattern of the monopole antenna, which shows that the left-handed material unit has not changed the original radiation pattern of the antenna while broadening the antenna bandwidth and reducing the antenna resonant frequency.

[0039] Fig.12Shown is the gain and radiation efficiency of the antenna in each resonant frequency band. It can be seen from the figure that at the resonant center frequencies of 2.41 GHz, 4.79 GHz, and 5.73 GHz, the antenna gains are -1.3 dB, 2.5 dB, and 2.9 dB, respectively. It can be seen that the gain at low frequencies is slightly lower. This is due to the small size of the antenna, which is acceptable for a small-sized monopole antenna.

[0040] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A multi-band miniaturized antenna based on a novel metamaterial unit loading, characterized in that: The invention comprises a symmetrical annular metal left-handed material unit (1), a coplanar waveguide feeding structure (3), a dielectric substrate (4), a metal feed line (5), and a metal horizontal bar (2) located directly below the symmetrical annular metal left-handed material unit (1); the symmetrical annular metal left-handed material unit (1), the metal horizontal bar (2), and the metal feed line (5) are located on the upper surface of the dielectric substrate (4), wherein one end of the metal feed line (5) is connected to the symmetrical annular metal left-handed material unit (1), and the metal horizontal bar (2) is connected to the metal feed line (5); when current flows through the metal horizontal bar (2), the metal feed line (5) is connected to the metal horizontal bar (2). When the horizontal strip (2) is formed, a new current path will be formed, thereby adding a new resonance point to the antenna; the coplanar waveguide feeding structure (3) comprises a portion located on the upper surface of the dielectric substrate (4) and a portion located on the lower surface of the dielectric substrate (4), wherein the portion located on the upper surface of the dielectric substrate (4) is a planar metal plate loaded on both sides of the metal feed line (5) and maintaining a gap with the metal feed line (5), and the portion located on the lower surface of the dielectric substrate (4) is a metal ground plate symmetrical to the upper surface, and the width of the metal ground plate is the same as the width of the dielectric substrate (4).

2. The multi-band miniaturized antenna based on novel metamaterial unit loading according to claim 1, characterized in that: The symmetrical annular metal left-handed material unit (1) is composed of two symmetrically distributed semicircular metal rings, with a gap between the two semicircular metal rings, wherein each semicircular metal ring is provided with a truncation at the top to form a notch, and a pair of symmetrical metal wires are added inwardly at the notch, with a gap between the symmetrical metal wires; the line widths of the various parts in the symmetrical annular metal left-handed material unit (1) are the same.

3. The multi-band miniaturized antenna based on novel metamaterial unit loading according to claim 2, characterized in that: By adjusting the distance between the symmetrical metal lines in the two semicircular metal rings, the size of the coupling capacitor can be adjusted, thereby changing the resonant frequency of the antenna.

4. The multi-band miniaturized antenna based on novel metamaterial unit loading according to claim 1, characterized in that: The input impedance of the metal feed line (5) is 50 ohms; and an SMA interface (6) is welded to the lower end of the metal feed line (5).

5. The multi-band miniaturized antenna based on novel metamaterial unit loading according to claim 3, characterized in that: The distance between the structural center of the symmetrical annular metal left-handed material unit (1) and the annular line R =5.8mm, line width of symmetrical circular metal left-handed material unit (1) W r = 0.4 mm, the length of the symmetrical metal wire in the symmetrical ring metal left-handed material unit (1) Lr =4.5mm, there is a gap between the symmetrical metal wires Gr =0.5mm.

6. The multi-band miniaturized antenna based on novel metamaterial unit loading according to claim 3, characterized in that: The length of the metal bar (2) L 1=12.5mm, width W 1=0.5mm; the width of the metal feed line (5) W 2 = 1 mm, when the metal horizontal bar (2) is connected to the metal feed line (5), the distance between the end of the metal feed line connected to the symmetrical annular metal left-handed material unit (1) and the metal horizontal bar (2) is L 3 = 1 mm, the vertical distance between the other end and the metal bar (2) L 2=10.5mm.

7. The multi-band miniaturized antenna based on novel metamaterial unit loading according to claim 3, characterized in that: The length of the planar metal plate in the coplanar waveguide feeding structure (3) is L 0 = 8.5mm, width W 0=8.5mm.

8. The multi-band miniaturized antenna based on novel metamaterial unit loading according to claim 1, characterized in that: The dielectric substrate (4) is an FR4 epoxy resin board, having a dielectric constant of 4.4, a relative magnetic permeability of 1.0, and a loss tangent value of 0.

002.

9. The multi-band miniaturized antenna based on novel metamaterial unit loading according to claim 8, characterized in that: The size is 23×14×0.8mm 3 A dielectric substrate (4).

10. The multi-band miniaturized antenna based on novel metamaterial unit loading according to any one of claims 1 to 3, characterized in that: The metal materials involved in the symmetrical annular metal left-handed material unit (1), the metal horizontal bar (2), the coplanar waveguide feeding structure (3), and the metal feed line (5) are all copper.

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