CN106816704A - The three port mimo antennas based on aperture slots - Google Patents

Abstract

A three-port MIMO antenna based on an open slot relates to a multi-port fed MIMO antenna. It includes a dielectric substrate. The dielectric substrate is provided with two circular dielectric substrates on the upper and lower layers. The two circular dielectric substrates are connected by 3 coaxial lines, and the 3 coaxial lines are symmetrically distributed at an angle of 120°. The outer conductor of the axis connects the metal layer on the lower surface of the lower dielectric substrate with the three fan-shaped metal layers on the lower surface of the upper dielectric substrate, and the inner conductor of the coaxial line connects with the metal strip layer on the upper surface of the upper dielectric substrate; the lower dielectric The lower surface of the substrate is coated with a metal layer; the lower surface of the upper dielectric substrate is coated with a metal layer. The metal layer is divided into three fan-shaped areas by three strip-shaped gaps, and each fan-shaped area is along the edge of the arc edge. There is a rectangular gap extending inside, and the upper surface of the upper dielectric substrate is coated with three boomerang-shaped strip-shaped metal layers, and the three boomerang-shaped strip-shaped metal layers are symmetrically distributed at an angle of 120° to each other.

Description

Three-port MIMO antenna based on open slot

technical field

The invention relates to a multi-port feeding MIMO antenna, in particular to a three-port MIMO antenna based on an open slot.

Background technique

The MIMO (Multiple-Input Multiple-Output) system uses the space diversity technology of multiple antennas to improve the channel capacity and transmission rate of the communication system, and has become one of the key technologies of the modern communication system. The multi-port MIMO antenna realizes the multiple-input multiple-output technology through the simultaneous operation of different ports, and the combination of multiple opening slots is a common method to realize multi-port operation. The open slot antenna has the advantages of simple structure, wide frequency band, low conductor loss, good isolation characteristics of the radiation unit and the feed network, etc. It also has the characteristics of low profile, small size, and easy integration with the surface of other circuits or systems[Akhavan H G, Mirshekar-Syahkal D. Study of coupled slot antennas fed by microstrip lines [C]. IEE conference publication. Institution of Electrical Engineers, 1997:1.290-1.293.].

At present, there are many multi-port antennas based on the slot structure applied to the MIMO system. For example [KarimianR, Oraizi H, Fakhte S, et al. Novel F-shaped quad-band printed slot antenna for WLAN and WiMAX MIMO systems [J]. Antennas and Wireless Propagation Letters, IEEE, 2013, 12:405-408.] It is the design and research of WLAN/WiMAX multi-port MIMO antenna composed of F-shaped slot structure. The multi-frequency antenna has 4 symmetrical feeding ports and realizes the MIMO antenna with diversity performance at the same time, but the isolation of this structure antenna is relatively low. Small, its value is less than 20dB. Literature [Vallecchi A, Gentili G B. Design of dual-polarized series-fed microstrip arrays with low losses and high polarization purity [J]. IEEE Transactions on Antennas and Propagation, 2005,53(5):1791-1798.] proposed A multi-polarized antenna connected in series with multiple H-shaped slots using coupled feeding, but the antenna has a complex structure and bidirectional radiation.

Contents of the invention

The purpose of the present invention is to provide a three-port MIMO antenna based on an open slot, which is simple in structure, has high port isolation and good directivity in the working frequency band, and is suitable for MIMO systems in the WLAN frequency band.

A three-port MIMO antenna based on an open slot, including a dielectric substrate, the dielectric substrate is provided with two circular dielectric substrates on the upper and lower layers, and the two circular dielectric substrates are connected by three coaxial cables, and the three coaxial cables They are distributed symmetrically at an angle of 120° to each other. The outer conductor of the coaxial line connects the metal layer on the lower surface of the lower dielectric substrate with the three fan-shaped metal layers on the lower surface of the upper dielectric substrate. The inner conductor of the coaxial line connects the upper surface of the upper dielectric substrate. The metal strip layer is connected; the lower surface of the lower dielectric substrate is coated with a metal layer; the lower surface of the upper dielectric substrate is coated with a metal layer, and the metal layer is divided into three fan-shaped areas by three strip-shaped gaps, each A fan-shaped area extends inward along the edge of the arc, and there is a rectangular gap. The upper surface of the upper dielectric substrate is coated with 3 boomerang-shaped strip metal layers, and the 3 boomerang-shaped strip metal layers form a 120° angle with each other. Symmetrical distribution.

further:

The lower dielectric substrate is a disc-shaped structure with a radius of 45-61 mm, a thickness of 1.1-1.3 mm, a relative dielectric constant of 3.0-3.4, and a loss tangent value not greater than 0.005; the upper dielectric substrate is also a disc Shaped structure with a radius of 39-45 mm and the same thickness as the lower dielectric substrate; the distance between the lower dielectric substrate and the upper dielectric substrate is 2.4-3.2 mm; the outer conductor diameter of the three coaxial lines is 2.8-3.6 mm, the inner conductor diameter is 0.7~1.1mm.

The distance from the center of the feed port of each coaxial line to the center of the lower dielectric substrate is 30.0-35.8 mm.

The strip-shaped slit has a length of 40.4-44.4mm and a width of 1.8-2.2mm, and the rectangular slit has a length of 13-17mm and a width of 2.5-3.5mm.

The boomerang-shaped strip metal layer is composed of a long arm and a short arm, the length of the long arm is 11-15 mm, the width is 2.0-3.0 mm, the length of the short arm is 6.5-10.5 mm, and the width is the same as that of the long arm. Width, the distance from the left side of the long arm to the center of the upper dielectric substrate is 29.6-33.6 mm, and the angle α between the long arm and the short arm is 150°.

Compared with the prior art, the present invention has the following outstanding advantages and remarkable effects:

The invention is a three-port antenna realized by combining multiple opening slots and coaxial feeding. The use of the open slot structure makes the antenna not only simple in structure, but also has high port isolation and good directivity in the working frequency band. The present invention is suitable for MIMO system in WLAN frequency band.

Description of drawings

Fig. 1 is a side view structural schematic diagram of an embodiment of the present invention.

FIG. 2 is a schematic top view of the lower surface of the lower dielectric substrate according to an embodiment of the present invention.

FIG. 3 is a schematic top view of the lower surface of the upper dielectric substrate according to an embodiment of the present invention.

FIG. 4 is a top view of the upper surface of the upper dielectric substrate according to the embodiment of the present invention.

Fig. 5 is a curve diagram of return loss of three ports of the antenna according to the embodiment of the present invention. In Fig. 5, curve a is the antenna return loss S11 curve; curve b is the antenna return loss S22 curve; curve c is the antenna return loss S33 curve.

FIG. 6 is a curve diagram of isolation between ports of the antenna according to an embodiment of the present invention.

Fig. 7 is an E-plane pattern diagram of the antenna when the first port is excited according to the embodiment of the present invention.

Fig. 8 is a diagram of the antenna H plane when the first port is excited according to the embodiment of the present invention.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Referring to FIG. 1 , the slot-based three-port MIMO antenna includes a lower dielectric substrate 1 , an upper dielectric substrate 2 and the same three coaxial wires 3 . The lower dielectric substrate 1 is a disc-shaped structure, the radius R1 is 48mm (can be 45-61mm), the thickness H is 1.2mm (can be 1.1-1.3mm), the relative dielectric constant is 3.0-3.4, and the loss tangent The value is not greater than 0.005; the upper dielectric substrate 2 is also a disc-shaped structure, the radius R2 is 42 mm (can be 39 to 45 mm), and the thickness is the same as that of the lower dielectric substrate 1; the lower dielectric substrate 1 and the upper dielectric substrate 2 The distance d5 between them is 2.8mm (can be 2.4-3.2mm); the outer conductor diameter R3 of the three coaxial lines is 3.2mm (can be 2.8-3.6mm), and the inner conductor diameter R4 is 0.9mm (can be 0.7～1.1mm).

Referring to FIG. 2 , it is a plan view of the lower surface of the lower dielectric substrate 1 . The feed ports 4, 5, 6 of the coaxial line are on the metal layer 7 on the lower surface of the lower substrate, and the distance L1 between their centers and the center of the lower dielectric substrate 1 is 32.9mm (can be 30.0-35.8mm).

Referring to FIG. 3 , it is a plan view of the lower surface of the upper dielectric substrate 2 . The length L2 of the same three strip-shaped slits 8 is 42.4 mm (may be 40.4-44.4 mm), and the width d3 is 2.0 mm (may be 1.8-2.2 mm). The length d1 of the three identical rectangular slits 9, 10, 11 is 15.0 mm (may be 13-17 mm), and the width d2 is 3.0 mm (may be 2.5-3.5 mm).

Referring to FIG. 4 , it is a top view of the upper surface of the upper dielectric substrate 2 . The three boomerang-shaped strip metal layers 12, 13, and 14 have the same structure, and are all composed of a long arm and a short arm. 2.0-3.0mm), the length L6 of the short arm is 8.5mm (it can be 6.5-10.5mm), and the width is the same as that of the long arm. The distance L4 from the left side of the long arm to the center of the upper dielectric substrate 2 is 31.6 mm (may be 29.6-33.6 mm), and the angle α between the long arm and the short arm is 150°.

Referring to FIG. 5 , it is a graph of return loss frequency curves of the three ports of the antenna. Due to the symmetry of the structure, the return loss curves of the three feed ports of the antenna are theoretically the same. It can be seen from the curves a1, b1 and c1 that the -10dB return loss bandwidth of the feed port ranges from 2.39 to 2.47GHz.

Referring to FIG. 6 , it is a curve diagram of isolation between each port of the antenna. In the working frequency band 2.39～2.47GHz, the isolation between ports 6 and 7 is shown in curve a2, and its value is greater than 20dB in the working frequency band, and the isolation between port 6 and port 8 is shown in curve b2 , whose value is greater than 20dB, the isolation between port 7 and port 8, as shown by curve b2, whose value is greater than 20dB.

Figures 7 to 8 are the directivity diagrams when the first port of the antenna is excited separately (the other two ports are connected to matching loads). Figure 7 is the E plane pattern of the antenna when the feed port 4 (or 5 or 6) is excited, and Figure 8 is the H plane pattern of the antenna when the feed port 4 (or 5 or 6) is excited. The main radiation direction is perpendicular to the plane where the antenna element is located and along the positive semi-axis of the Z axis, the maximum gain reaches 8dBi, and the main lobe width of the antenna is about 60 degrees.

Claims (5)

1. A three-port MIMO antenna based on an open slot, including a dielectric substrate, characterized in that the dielectric substrate is provided with two circular dielectric substrates on the upper and lower layers, and the two circular dielectric substrates are connected by three coaxial cables , the three coaxial lines are symmetrically distributed at an angle of 120° to each other. The outer conductor of the coaxial line connects the metal layer on the lower surface of the lower dielectric substrate with the three fan-shaped metal layers on the lower surface of the upper dielectric substrate. The inner conductor of the coaxial line is connected to the The metal strip layer on the upper surface of the upper dielectric substrate is connected; the lower surface of the lower dielectric substrate is coated with a metal layer; the lower surface of the upper dielectric substrate is coated with a metal layer, and the metal layer is divided into three strip-shaped gaps. Three fan-shaped areas, each fan-shaped area extends inward along the edge of the arc to open a rectangular gap, the upper surface of the upper dielectric substrate is coated with 3 boomerang-shaped strip metal layers, and 3 boomerang-shaped strip metal layers The layers are symmetrically distributed at an angle of 120° to each other. 2. The three-port MIMO antenna based on an open slot as claimed in claim 1, wherein the lower dielectric substrate is a disc-shaped structure with a radius of 45-61 mm, a thickness of 1.1-1.3 mm, and a relative permittivity of 3.0 to 3.4, the loss tangent value is not greater than 0.005; the upper dielectric substrate is also a disc-shaped structure with a radius of 39 to 45 mm and the same thickness as the lower dielectric substrate; the distance between the lower dielectric substrate and the upper dielectric substrate 2.4-3.2mm; the diameter of the outer conductor of the three coaxial lines is 2.8-3.6mm, and the diameter of the inner conductor is 0.7-1.1mm. 3 . The slot-based three-port MIMO antenna according to claim 1 , wherein the distance from the center of the feeding port of each coaxial line to the center of the lower dielectric substrate is 30.0-35.8 mm. 4 . 4. The three-port MIMO antenna based on the open slot according to claim 1, wherein the length of the strip-shaped slot is 40.4-44.4 mm, the width is 1.8-2.2 mm, and the length of the rectangular slot is 13-2 mm. 17mm, width 2.5 ~ 3.5mm. 5. The three-port MIMO antenna based on the opening slot as claimed in claim 1, wherein the boomerang-shaped strip metal layer is composed of a long arm and a short arm, the length of the long arm is 11-15mm, and the width The length of the short arm is 6.5-10.5mm, the width is the same as the width of the long arm, the distance from the left side of the long arm to the center of the upper dielectric substrate is 29.6-33.6mm, and the angle α between the long arm and the short arm is 150°.