TWI872646B - Mimo antenna array - Google Patents

Abstract

A MIMO antenna array includes at least two four-antenna units, each of the four-antenna units includes four antennas operating in the same communication frequency band, a substrate layer, and a ground plane. Each of the antennas has a radiation metal patch, and each of the radiation metal patch is adjacent to two of the radiation metal patches. The four radiation metal patches are located above the ground plane, and the substrate layer is located between the four radiation metal patches and the ground plane. Wherein, a distance between the adjacent four-antenna units is less than 0.12 wavelength of the lowest operating frequency of the communication frequency band.

Description

Multiple-Input Multiple-Output Antenna Array

The present invention relates to an antenna array, and more particularly to a multi-input multi-output (MIMO) antenna array. The multi-input multi-output antenna array has at least two four-antenna units, and the adjacent four-antenna units are arranged at a close distance, so that the antenna array has a small size and good isolation, and is suitable for multi-input multi-output operation of a communication terminal.

The MIMO system has the advantages of improving spectral efficiency and significantly increasing data transmission throughput. It has been widely used in the fourth generation (4G) communication system and the fifth generation (5G) communication system, and is still the technical focus of the future sixth generation (6G) communication system. Generally, the 5G communication system is configured with a 4 × 4 MIMO system consisting of 4 transmitting antennas and 4 receiving antennas. However, compared with the fifth generation 4 × 4 MIMO system, the communication terminals of the sixth generation communication system are expected to support higher-order MIMO systems, such as at least 8 × 8 MIMO systems, in order to obtain higher spectral efficiency of the terminals. Therefore, in the future, the number of MIMO antennas in communication terminals will need to increase significantly. If the number of antennas in the communication terminal is greater than the number of MIMO signal streams transmitted by the base station (for example, 12 × 8 MIMO or 16 × 8 MIMO or 16 × 12 MIMO), signal transmission can support higher modulation, further improving the terminal spectrum efficiency, while improving the reliability and invisibility of signal transmission. However, how to implement more MIMO antenna deployment in the limited space of the terminal device while maintaining good isolation and good antenna efficiency between antennas is a huge challenge and an important issue that needs to be solved in this field.

The main purpose of the present invention is to provide a multiple-input multiple-output antenna array with a close spacing, which can be applied to communication terminals (such as smart phones, wearable devices, tablet computers, and Internet of Things devices, etc.), and the number of MIMO antennas of the communication terminal is maximized by the close spacing. It is particularly suitable for communication terminals of the sixth generation communication system and is expected to support at least 8×8 MIMO systems to obtain higher spectral efficiency of the communication terminal.

A multiple-input multiple-output antenna array of the present invention comprises at least two four-antenna units, each of which comprises four antennas operating in the same communication band, a base layer and a ground plane, each of which has a radiation metal plate, wherein each of the radiation metal plates is adjacent to two of the radiation metal plates, the four radiation metal plates are located above the ground plane, the base layer is located between the four radiation metal plates and the ground plane, and a distance between adjacent four-antenna units is less than 0.12 wavelength of the lowest operating frequency of the communication band.

The present invention has a compact structure because the distance between adjacent four-antenna units is less than 0.12 wavelength of the lowest operating frequency of the communication band, and each of the four-antenna units includes four antennas, so that the multiple-input multiple-output antenna array at least constitutes an 8-antenna array and is suitable for the sixth-generation communication system.

Please refer to FIG. 1, which is a top view of a MIMO antenna array 100 according to a first embodiment of the present invention. The MIMO antenna array 100 includes two four-antenna units 110, and the at least two four-antenna units 110 have the same size. Please refer to FIG. 2, which is a structural diagram of a single four-antenna unit 110 of the MIMO antenna array 100. Each of the four-antenna units 110 includes The MIMO antenna array 100 includes four antennas 111 operating in the same communication frequency band, a base layer 112, and a ground plane 113. Since the two four-antenna units 110 have a total of eight antennas 111, the MIMO antenna array 100 of this embodiment is an eight-antenna array. In other embodiments, the MIMO antenna array 100 may include more four-antenna units 110. The eight-antenna array is not limited to the present invention.

Please refer to FIG. 2 , in this embodiment, each antenna 111 has a radiating metal sheet 111a and at least one feeding point (not shown), each radiating metal sheet 111a is substantially a square, wherein each radiating metal sheet 111a is adjacent to two radiating metal sheets 111a, and the four radiating metal sheets 111a are located above the ground plane 113. The feeding point can be electrically connected or coupled to the radiating metal sheet 111a, and the feeding point is used for inputting a current signal and transmitting it to the radiating metal sheet 111a. The base layer 112 is located between the four radiation metal sheets 111a and the ground plane 113. A thickness h1 of the base layer 112 is not greater than 1 mm or less than 0.04 wavelength of the lowest operating frequency of the same communication band. The base layer 112 of this embodiment is a single dielectric layer, which can be an air layer or a dielectric material layer.

Please refer to FIGS. 1 and 2. In this embodiment, the thickness h1 of the substrate 112 is not greater than 1 mm or less than 0.04 wavelength of the lowest operating frequency of the same communication band and has a lower substrate thickness. Under the lower substrate thickness, the fringing electric or magnetic field of the four antenna units 110 is As the distance from the edge increases, the electric field or magnetic field of each of the four antenna units 110 will decay faster, so the edge electric field or magnetic field of each of the four antenna units 110 is not easy to couple to the adjacent four antenna units 110, and when a distance t1 between the adjacent four antenna units 110 is reduced (less than 0.12 wavelength of the lowest operating frequency), the antennas 111 of the adjacent four antenna units 110 can still maintain good isolation. In this embodiment, the distance t1 is less than 0.12 wavelength of the lowest operating frequency of the communication band, thereby achieving the effect of closely arranging the four antenna units 110.

Please refer to FIG. 3, which is a top view of the MIMO antenna array 100 of the second embodiment of the present invention. The difference between the second embodiment and the first embodiment is that the MIMO antenna array 100 includes three 4-antenna units 110, and each 4-antenna unit 110 has four antennas 111 to form a 12-antenna array, which can achieve higher spectrum efficiency at the communication terminal. Similarly, the spacing t2 and t3 between two adjacent 4-antenna units 110 are both less than 0.12 wavelength of the lowest operating frequency of the communication band, so that the MIMO antenna array 100 with a close spacing can be achieved.

Please refer to FIG. 4, which is a top view of a third embodiment of the MIMO antenna array 100 of the present invention. The difference between the third embodiment and the first embodiment is that the MIMO antenna array 100 includes four quad-antenna units 110, each of which is adjacent to two quad-antenna units 110, and each of which is adjacent to two quad-antenna units 110. 0 has four antennas 111 to form a 16-antenna array, which can achieve higher spectrum efficiency at the communication terminal. Similarly, the spacing t4 and t5 between two adjacent four-antenna units 110 are both less than 0.12 wavelength of the lowest operating frequency of the communication band, so that a multi-input multi-output antenna array 100 with a close spacing can be achieved.

Please refer to FIG. 5, which is a structural diagram of a single four-antenna unit 110 of a fourth embodiment of the MIMO antenna array 100. The four-antenna unit 110 includes four radiation metal sheets 111b. The difference between this embodiment and the first embodiment of FIG. 2 is that each radiation metal sheet 111b is substantially rectangular, and each radiation metal sheet 111b is adjacent to two radiation metal sheets 111b. Through the arrangement of the rectangular radiation metal sheets 111b, the resonance modes of the adjacent antennas can be excited along the long side direction of the rectangular radiation metal sheets and are substantially perpendicular to each other, thereby increasing the isolation between the radiation metal sheets 111b. The four radiating metal sheets 111b are located above the ground plane 113, the base layer 112 is located between the four radiating metal sheets 111b and the ground plane 113, and the thickness h1 of the base layer 112 is not greater than 1 mm or less than 0.04 wavelength of the lowest operating frequency of the communication band.

Please refer to FIG. 6 , which is a structural diagram of a single quad-antenna unit 110 of a fifth embodiment of the MIMO antenna array 100. The difference from the fourth embodiment of FIG. 5 is that the base layer 112 is composed of a dielectric layer 112a and an air layer 112b, and the dielectric layer 112a is a dielectric material layer. In other embodiments, the base layer 112 may also be composed of at least two different dielectric layers including an air layer. The base layer 112 of the present embodiment has the air layer 112b, and therefore has a lower equivalent dielectric constant, which can improve the operating bandwidth of each antenna 111 of each of the four antenna units 110, so that the MIMO antenna array 100 of the present invention has a higher practical application value.

The present invention has a compact structure because the distance between the adjacent four-antenna units 110 is less than 0.12 wavelength of the lowest operating frequency of the communication band, and each of the four-antenna units 110 includes four antennas 111, so that the MIMO antenna array 100 at least constitutes an 8-antenna array and is applicable to the sixth generation communication system.

The scope of protection of the present invention shall be determined by the scope of the attached patent application. Any changes and modifications made by anyone familiar with this technology without departing from the spirit and scope of the present invention shall fall within the scope of protection of the present invention.

100: MIMO antenna array 110: Four antenna units 111: Antenna 111a, 111b: Radiation metal sheet 112: Base layer 112a: Dielectric layer 112b: Air layer 113: Ground plane t1, t2, t3, t4, t5: Spacing h1: Thickness

Figure 1: A top view of a multi-input multi-output antenna array according to the first embodiment of the present invention. Figure 2: A structural diagram of a four-antenna unit of the multi-input multi-output antenna array according to the first embodiment of the present invention. Figure 3: A top view of a multi-input multi-output antenna array according to the second embodiment of the present invention. Figure 4: A top view of a multi-input multi-output antenna array according to the third embodiment of the present invention. Figure 5: A structural diagram of a four-antenna unit of a multi-input multi-output antenna array according to the fourth embodiment of the present invention. Figure 6: A structural diagram of a four-antenna unit of a multi-input multi-output antenna array according to the fifth embodiment of the present invention.

100:Multiple-input and multiple-output antenna array

110: Four-antenna unit

111: Antenna

113: Ground contact surface

t1: Spacing

Claims (9)

A multiple-input multiple-output antenna array includes at least two four-antenna units, each of which includes: Four antennas operating in the same communication band, each of which has a radiating metal sheet, wherein each of the radiating metal sheets is adjacent to two of the radiating metal sheets; A base layer; and A ground plane; wherein the four radiating metal sheets are located above the ground plane, the base layer is located between the four radiating metal sheets and the ground plane, and a distance between adjacent four-antenna units is less than 0.12 wavelength of the lowest operating frequency of the communication band. The MIMO antenna array of claim 1, wherein the at least two quad-antenna units have the same size. The MIMO antenna array of claim 1, wherein the thickness of the substrate layer is no greater than 1 mm. The MIMO antenna array of claim 1, wherein the thickness of the substrate layer is less than 0.04 wavelength of the lowest operating frequency of the same communication band. The MIMO antenna array of any one of claims 1 to 4, wherein the base layer is a single dielectric layer or a combination of at least two different dielectric layers including an air layer. The MIMO antenna array of claim 1 comprises at least three four-antenna units, wherein the at least three four-antenna units have the same size. The MIMO antenna array of claim 1 comprises at least four four-antenna units, wherein each of the four-antenna units is adjacent to two of the four-antenna units. A MIMO antenna array as claimed in claim 7, wherein the at least four quad-antenna units have the same size. The MIMO antenna array of claim 1, wherein each of the radiating metal sheets is square or rectangular.

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