A broadband antenna based on metamaterials

Abstract

The present invention discloses a broadband antenna based on metamaterials, which relates to the technical field of mobile communication. The key points of its technical solution are as follows: The top surface of the dielectric plate is printed with a surface set and two pincer-shaped microstrip feed lines, and the bottom surface of the dielectric plate is printed with four antenna radiation patches and four parasitic patches; The surface set is composed of a plurality of metamaterial surfaces in the shape of an L, and the plurality of metamaterial surfaces are arranged around the radiation patches. By loading the metamaterial surface and the antenna on the same dielectric plate, the antenna structure can be made simple. At the same time, through the coupling between the antenna and the metamaterial surface, a new resonance mode is generated, thereby broadening the working frequency band. At the same time, the metamaterial surface located above the antenna changes the radiation characteristics of the antenna, increasing the gain and solving the problem of poor impedance matching caused by the reduction of the antenna height. This broadband antenna based on metamaterials can be used in the working frequency bands of 4G and 5G.

Description

Technical Field

[0001] The present invention relates to the field of mobile communication technologies, and more specifically, to a broadband antenna based on metamaterials. Background Art

[0002] Modern wireless communication systems have undergone decades of development, and the user experience has been greatly improved. Up to now, 4G networks have been well popularized in the development of modern wireless communication systems, and 5G communication has gradually become a hot topic in today's wireless communication systems. 4G operates in the frequency band of 2300 MHz - 2690 MHz, and the sub-6G frequency band of 5G is 3300 MHz - 3600 MHz and 4800 MHz - 5000 MHz. Enabling the coexistence of 4G and 5G mobile communication systems is of great significance for meeting the requirements of broadband and multi-band base station antennas.

[0003] Dual-polarized antennas provide polarization diversity to reduce the side effects of multipath fading and can also increase the channel capacity. Dual-polarized antennas can achieve broadband operation of the antenna. At the same time, research on using metamaterials to achieve antenna broadbanding has received extensive attention. In existing technologies, miniaturization, broadbanding, and multi-band operation of the antenna can be achieved by loading a metamaterial surface. It has a periodic structure and has excellent reflection and radiation characteristics for incident electromagnetic waves. However, selecting a suitable metamaterial surface unit structure is an important issue.

[0004] Chinese Patent Application (CN113488761A) discloses a 5G broadband dual-polarized base station antenna. In this invention, two T-shaped feed lines are connected to one end of a feed coaxial cable, and the other end of the feed coaxial cable is connected to a metal reflector to achieve feeding. The metal reflector is used to reduce backward radiation and thus improve the antenna gain; a metal baffle is used to increase the gain and control the beam width. However, the operating frequency band of this invention is only 3.3 - 5 GHz, so it cannot meet the actual application requirements of miniaturization and multi-band operation in modern mobile communications. Summary of the Invention

[0005] The object of the present invention is to provide a broadband antenna based on metamaterials. By loading the metamaterial surface and the antenna on the same dielectric plate, the antenna structure can be made simple. At the same time, through the coupling between the antenna and the metamaterial surface, a new resonance mode is generated, thereby broadening the operating frequency band. At the same time, the metamaterial surface located above the antenna changes the radiation characteristics of the antenna, increases the gain, and solves the problem of poor impedance matching caused by the reduction of the antenna height. This broadband antenna based on metamaterials can be used in the operating frequency bands of 4G and 5G.

[0006] The above technical object of the present invention is achieved by the following technical solutions: A broadband antenna based on metamaterials, including a dielectric board, on the top surface of the dielectric board, a surface set and two clamp-shaped microstrip feed lines are printed, and on the bottom surface of the dielectric board, four antenna radiation patches and four parasitic patches are printed; the surface set is composed of a plurality of metamaterial surfaces in the shape of an L, and the plurality of metamaterial surfaces are arranged around the radiation patches;

[0007] Two metal shorting posts are arranged in the dielectric board, the two clamp-shaped microstrip feed lines are cross-distributed, and one of the clamp-shaped microstrip feed lines is connected to the two metal shorting posts at the cross position to achieve a bridge connection process;

[0008] A metal reflection cavity with an open top is arranged directly below the dielectric board, and two coaxial lines are fixedly arranged at the bottom of the metal reflection cavity; the tops of the two baluns are connected to the antenna radiation patches; the coaxial line includes an inner core and an outer conductor wrapped on the surface of the inner core; the tops of the two outer conductors are fixedly connected to the bottom surface of the dielectric board, and the tops of the two inner cores pass through the dielectric board and are respectively connected to the ends of the clamp-shaped microstrip feed lines.

[0009] The present invention is further arranged as: the bottom surface of the metal reflection cavity is square, and the middle position of the side wall of the metal reflection cavity is open and a horizontal reflection plate is arranged outward.

[0010] The present invention is further arranged as: the four parasitic patches are all rectangular, and the four parasitic patches are annularly distributed along the geometric center of the dielectric board.

[0011] The present invention is further arranged as: the height of the broadband antenna is less than 0.25 times the wavelength of its operating center frequency.

[0012] The present invention is further arranged as: the edge of the antenna radiation patch is an irregular zigzag shape.

[0013] In summary, the present invention has the following beneficial effects:

[0014] 1. By adding four parasitic patches, the present invention increases the current path, effectively improves the matching impedance of the antenna, and realizes the broadband of the broadband antenna;

[0015] 2. By loading the metamaterial surface on the top surface of the dielectric board, the present invention realizes the miniaturization of the integration of the metamaterial surface and the antenna on one dielectric board;

[0016] 3. By opening the middle of the metal reflector, the present invention effectively solves the problem of excessive cross polarization, and adds a small horizontal reflector at the opening to improve the gain;

[0017] 4. The metamaterial surface effectively enhances the radiation characteristics of the antenna and improves the gain of the antenna;

[0018] 5. By setting the clamp-shaped microstrip feeder, the feeding area of the microstrip feeder for the antenna radiation patch is increased, effectively improving the impedance matching and increasing the bandwidth.

[0019] 6. When reducing the height of the antenna, it will cause the problem of impedance mismatch. A broadband antenna based on metamaterials proposed by the present invention achieves a lower height and a wider operating bandwidth, thus facilitating the coexistence of 4G and 5G frequency bands.

[0020] 7. The relative bandwidth of the present invention can reach 74%, achieving the broadbandization of the broadband antenna.

[0021] 8. The average gain of the present invention is greater than 9 dBi, achieving the high gain of the broadband antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a perspective view of a broadband antenna based on metamaterials in an embodiment of the present invention;

[0023] Figure 2 is a schematic structural diagram of the dielectric substrate in an embodiment of the present invention;

[0024] Figure 3 is the standing wave ratio curve of a broadband antenna based on metamaterials in the 2300 MHz - 5000 MHz frequency band in an embodiment of the present invention;

[0025] Figure 4 is the gain curve of a broadband antenna based on metamaterials in the 2300 MHz - 5000 MHz frequency band in an embodiment of the present invention.

[0026] In the figure: 1. Dielectric substrate; 2. Antenna radiation patch; 3. Inner core; 4. Outer conductor; 5. Metal reflection cavity; 6. Balun; 7. Parasitic patch; 8. Metamaterial surface; 9. Clamp-shaped microstrip feeder; 10. Metal shorting post; 11. Horizontal reflector. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following further describes the present invention in detail Figures 1-4 with reference to the accompanying drawings.

[0028] Embodiment: A broadband antenna based on metamaterials, as Figure 1 . Figure 2 shown, includes a dielectric substrate 1. On the top surface of the dielectric substrate 1, a surface set and two clamp-shaped microstrip feeders 9 are printed. On the bottom surface of the dielectric substrate 1, four antenna radiation patches 2 and four parasitic patches 7 are printed. The surface set is composed of 20 L-shaped metamaterial surfaces 8. The 20 metamaterial surfaces 8 are as Figure 1As shown, the surrounding radiation patch 2 is arranged; the overall periodic structure of the metamaterial surface 8 has specific scattering characteristics for the electromagnetic waves emitted by the antenna radiation patch 2, which can improve the gain and adjust the directivity pattern; and a single metamaterial surface 8 unit can be regarded as a small resonant patch of a special shape. The resonant patches at different positions can generate different current paths, thereby effectively expanding the working bandwidth of the antenna. The equidistant distribution of each L-shaped metamaterial surface is to effectively control the position of the resonant mode, which is the key to realizing a broadband antenna.

[0029] Four antenna radiation patches 2 and four parasitic patches 7 are printed on the bottom surface of the dielectric plate 1; the edges of the four antenna radiation patches 2 are irregular zigzag shapes, and are arranged as follows: Figure 2 Arranged in the manner shown, the current of the antenna radiation patch 2 is most densely distributed at the edge of the patch, and the irregular sawtooth antenna radiation patch 2 can change the current path and effectively expand the working bandwidth; two metal short-circuit posts 10 are fixedly installed in the dielectric plate 1, and two clamp-type microstrip feed lines 9 are cross-distributed, and one of the clamp-type microstrip feed lines 9 is located at the cross position and connected to the two metal short-circuit posts 10 to realize bridge processing;

[0030] A metal reflection cavity 5 with an opening on the top is provided directly below the dielectric plate 1, and two coaxial lines are fixedly provided at the bottom of the metal reflection cavity 5; the tops of two baluns 6 are connected to the antenna radiation patch 2, and the balun 6 is used to adjust the impedance matching and reduce the cross polarization. Placing the balun 6 in the middle of the antenna radiation patch 2 can effectively adjust the position of the resonant mode at the low frequency, thereby improving the impedance matching; the coaxial line includes an inner core 3 and an outer conductor 4 wrapped around the surface of the inner core 3; the tops of the two outer conductors 4 are fixedly connected to the bottom surface of the dielectric plate 1, and the tops of the two inner cores 3 pass through the dielectric plate 1 and are respectively connected to the ends of the clamp-shaped microstrip feed line 9, so that the microstrip feed line can be effectively fed, and at the same time, the coaxial line outer conductor 4 is prevented from contacting the antenna radiation patch 2, so that energy transmission between the microstrip feed line and the antenna radiation patch 2 can be achieved in a coupled feeding manner, thereby achieving the effect of expanding the working bandwidth.

[0031] Preferably, in this embodiment, the bottom surface of the metal reflection cavity 5 is square, the middle position of the side wall of the metal reflection cavity 5 is open and a horizontal reflection plate 11 is provided outwardly to reflect electromagnetic waves, control the beam width and increase the gain.

[0032] Preferably, in this embodiment, the four parasitic patches 7 are all rectangular, and the four parasitic patches 7 are distributed in a ring shape along the geometric center of the dielectric plate 1 .

[0033] Preferably, in this embodiment, the height of the broadband antenna is less than 0.25 times the wavelength of its operating center frequency.

[0034] from Figure 3 and Figure 4It can be seen that the standing wave ratio is less than 1.5 in the working frequency band, and the average gain is above 9 dBi, realizing the characteristics of wide bandwidth and high gain of the broadband antenna.

[0035] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A broadband antenna based on metamaterials, comprising a dielectric substrate (1), Characterized in that: On the top surface of the dielectric substrate (1), a surface set and two clamp-shaped microstrip feed lines (9) are printed. On the bottom surface of the dielectric substrate (1), four antenna radiation patches (2) and four parasitic patches (7) are printed; the surface set is composed of a plurality of metamaterial surfaces (8) in the shape of an L, and the plurality of metamaterial surfaces (8) are arranged around the antenna radiation patches (2); Two metal shorting posts (10) are provided inside the dielectric substrate (1). The two clamp-shaped microstrip feed lines (9) are cross-distributed, and one of the clamp-shaped microstrip feed lines (9) is connected to the two metal shorting posts (10) at the cross position to achieve a bridge connection; A metal reflection cavity (5) with an open top is provided directly below the dielectric substrate (1). Two coaxial lines are fixedly provided at the bottom of the metal reflection cavity (5); the tops of two baluns (6) are connected to the antenna radiation patches (2); the coaxial line includes an inner core (3) and an outer conductor (4) wrapped on the surface of the inner core (3); the tops of the two outer conductors (4) are fixedly connected to the bottom surface of the dielectric substrate (1), and the tops of the two inner cores (3) pass through the dielectric substrate (1) and are respectively connected to the ends of the clamp-shaped microstrip feed lines (9).

2. A broadband antenna based on metamaterials according to claim 1, Characterized in that: The bottom surface of the metal reflection cavity (5) is square, and the middle position of the side wall of the metal reflection cavity (5) is open and a horizontal reflector (11) is provided outward.

3. A broadband antenna based on metamaterials according to claim 1, Characterized in that: The four parasitic patches (7) are all rectangular, and the four parasitic patches (7) are annularly distributed along the geometric center of the dielectric substrate (1).

4. A broadband antenna based on metamaterials according to claim 1, Characterized in that: The height of the broadband antenna is less than 0.25 times the wavelength of its operating center frequency.

5. A broadband antenna based on metamaterials according to claim 1, Characterized in that: The edge of the antenna radiation patch (2) is an irregular zigzag.

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