CN110635232A

CN110635232A - Dual-polarized microstrip antenna unit with wide-angle broadband scanning capability

Info

Publication number: CN110635232A
Application number: CN201910768027.8A
Authority: CN
Inventors: 李鹏发; 屈世伟; 李小秋; 杨仕文; 孙红兵; 周志鹏
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2019-08-20
Filing date: 2019-08-20
Publication date: 2019-12-31
Anticipated expiration: 2039-08-20
Also published as: CN110635232B

Abstract

The invention discloses a dual-polarized microstrip antenna unit suitable for wide-angle and broadband scanning, and belongs to the technical field of antenna engineering. The antenna consists of a laminated patch layer, a dual-polarized feed layer and a metal bottom plate; the laminated patch layer comprises two layers of PCB boards and uses a metal wall as a support; the feed layer comprises a horizontally polarized microstrip feed line, a cross coupling slot on the ground and a vertically polarized asymmetric strip line feed, and the feed layers are respectively arranged on the three layers of PCB boards. The mechanical strength and stability of the antenna are improved through the metal wall and the metal bottom plate; the air cavity supported by the metal wall increases the bandwidth of the antenna, avoids the use of a PCB with low dielectric constant, and reduces the number of layers of the PCB, thereby reducing the alignment error in the assembling process and lowering the cost; the feed layer avoids blind holes, reduces the processing difficulty and reduces the processing cost. Simulation and experiment results show that the antenna unit is used in a phased array, 15% of relative bandwidth can be realized, grating lobes and high side lobes do not appear when scanning +/-45 degrees in the bandwidth, active standing waves are lower than 2.5, cross polarization is lower than-20 dB, and isolation is higher than 23 dB.

Description

Dual-polarized microstrip antenna unit with wide-angle broadband scanning capability

Technical Field

The invention belongs to the technical field of antenna engineering, and relates to a dual-polarized microstrip antenna unit capable of realizing wide-angle and broadband scanning.

Background

The dual-polarized antenna can double the frequency spectrum utilization rate, is widely applied to a communication system, and can obtain different imaging information of a target in different polarizations in the fields of radar detection and imaging; the microstrip antenna has the advantages of low profile, simple structure, low processing cost and the like, but the bandwidth of the common microstrip antenna is only 2% -5%, so that the application of the microstrip antenna is limited. In the document 'Wide-band microstrip antenna with an H-shaped coupling antenna', the bandwidth of a microstrip antenna is increased by using a laminated patch; in the document "Dual polarized wide-band antenna patch antenna", a cross-shaped coupling slot and a Y-shaped feeder line are used for exciting a laminated patch, so that a broadband Dual-polarized microstrip antenna is realized. However, the antenna in the document is a single antenna, is large in size, and is not suitable as a phased array antenna unit because scanning characteristics in an array environment are not examined.

On the basis, a phased array laminated microstrip antenna unit suitable for wide-angle and broadband scanning is further designed in the document of' a cross-phased radiating antenna with enhanced scanning performance for digital beam forming. However, this antenna unit uses 8 layers of dielectric and uses a large number of blind holes. Firstly, the processing and assembling errors are increased; secondly, the processing difficulty and cost are increased due to a large number of blind holes and a medium laminated structure, and the cost is also increased due to the fact that the antenna layer is made of a low-dielectric-constant RT/duroid 5880LZ material; and thirdly, the antenna lacks a metal framework, and the mechanical strength of the dielectric material is insufficient. Finally, the active standing wave versus frequency curve of the antenna element at different scan angles is not given.

Disclosure of Invention

On the basis of the background technology, the invention provides a dual-polarized microstrip antenna unit which is high in mechanical strength, low in processing difficulty and low in cost, and has wide-angle and broadband scanning capabilities.

The technical scheme adopted by the invention is as follows: a dual polarized microstrip antenna element having wide angle broadband scanning capability, the antenna element comprising: the stacked patch layer, the dual-polarized feed layer and the metal bottom plate are sequentially stacked from top to bottom;

the laminated patch layer includes: the PCB comprises a first laminated patch, a first PCB board layer, a second laminated patch, a second PCB board layer and a metal frame; the first laminated patch is arranged on the upper surface of the first PCB layer, and the area of the first laminated patch is smaller than that of the upper surface of the first PCB layer; the second laminated patch is arranged on the upper surface of the second PCB layer, and the area of the second laminated patch is smaller than that of the upper surface of the second PCB layer; the second PCB plate layer is embedded in the metal frame, and the first PCB plate layer is supported by the metal frame, so that an air cavity layer is formed between the first PCB plate layer and the second PCB plate layer;

the dual polarized feed layer comprises: the PCB comprises a third PCB layer, a fourth PCB layer and a fifth PCB layer which are sequentially stacked from top to bottom, wherein a horizontal polarization feeder line is arranged on the upper surface of the third PCB layer, a cross-shaped coupling groove is arranged in the fourth PCB layer, and a vertical polarization feeder line is arranged on the upper surface of the fifth PCB layer;

a vertical polarization feed probe and a horizontal polarization feed probe are arranged on the metal bottom plate, the vertical polarization feed probe sequentially penetrates through a fifth PCB (printed circuit board) layer and a fourth PCB layer from the metal bottom plate to reach the lower surface of the third PCB layer, and the vertical polarization feed probe is connected with the input end of a vertical polarization feed line arranged on the upper surface of the fifth PCB layer when penetrating through the fifth PCB layer; the horizontal polarization feed probe sequentially penetrates through a fifth PCB (printed circuit board) layer, a fourth PCB layer and a third PCB layer from the metal bottom plate to reach the lower surface of the second PCB layer, and is connected with the input end of the horizontal polarization feed line arranged on the upper surface of the third PCB layer when penetrating through the third PCB layer;

and a circle of metalized through holes are formed in the dual-polarized feed layer and used for surrounding the horizontal polarized feed line, the vertical polarized feed probe and the horizontal polarized feed probe.

Furthermore, the horizontal polarization feeder line is a Y-shaped microstrip line along the Y direction, and the vertical polarization feeder line is a Y-shaped strip line along the x direction.

Furthermore, the tail end of each branch of the cross-shaped coupling groove is provided with a rectangular groove which is wider than the cross-shaped coupling groove and is communicated with the cross-shaped coupling groove; the depth rectangular grooves of the cross-shaped coupling grooves are the same and equal to the thickness of the fourth PCB layer.

Furthermore, two through holes are arranged in the metal bottom plate and are respectively connected with the horizontal polarization feed probe and the vertical polarization feed probe.

Furthermore, the shape and size of the second laminated patch are the same as the shape and size defined by a circle of metalized through holes arranged in the dual-polarized feed layer, and the first laminated patch is positioned right above the second laminated patch and has an area larger than that of the second laminated patch.

Further, the horizontally polarized feed line comprises two parts: the top point of the 1-type microstrip line part is connected with the middle point of the lower bottom edge of the U-type microstrip line part, and the bottom point of the 1-type microstrip line part is an input point.

The metal wall and the metal bottom plate are used as the antenna framework, so that the mechanical strength and the stability of the antenna are improved; the metal wall supports the air cavity, so that the bandwidth of the antenna is increased, the use of a PCB with low dielectric constant is avoided, and the number of layers of the PCB is reduced, thereby reducing the alignment error in the assembling process and reducing the cost; the feed layer avoids blind holes, reduces the processing difficulty and reduces the processing cost.

Drawings

Fig. 1 is a schematic 3D structure of the present invention.

Fig. 2 is a graph of Active standing wave (Active VSWR) versus frequency for periodic unit simulation in an infinite array environment, where (a) and (b) are graphs of vertical and horizontal polarization performance, respectively.

FIG. 3 is a schematic diagram of a 5X 5 array in which the columns around the cells are the locations of the screws during the splicing process.

FIG. 4 is a graph of the variation of horizontally polarized active standing waves of a central unit of a 5 × 5 array with frequency, wherein (a), (b) and (c) are simulation and test results of an H surface, a D surface and an E surface respectively.

Fig. 5 is a curve of transmission coefficients between dual-polarized ports of a central unit of a 5 × 5 array.

Fig. 6 is a simulated and actually measured gain directional diagram of 5 × 5 array at 4.2GHz, wherein the diagrams (a), (b) and (c) are a central unit directional diagram, an E-plane scanning directional diagram and an H-plane scanning directional diagram in sequence.

Fig. 7 is a front view of fig. 1.

Fig. 8 is a plan view of the layer structures of fig. 1.

Detailed Description

In the embodiment, the structure of the antenna unit is shown in fig. 1, the antenna is integrally divided into six layers, namely five

PCB board layers

10, 20, 30, 40 and 50 and a metal bottom board 62, the thicknesses of the five PCB board layers are 0.5mm, 1.5mm, 0.5mm, 3mm and 3mm in sequence, and the dielectric constant of the PCB board is 2.2; wherein, the

layers

10 and 20 and the metal frame 22 form a laminated patch layer, the thickness of the metal frame is 5mm, and the

layers

30, 40 and 50 form a feed layer; the unit size is 40X 40mm²。

The laminated

patches

11 and 21 are square patches with side lengths of 25.5mm and 19mm, respectively, and the width of the inner wall of the metal frame is 38 mm.

The line widths of a trunk line and branch lines of the horizontally polarized Y-shaped feeder line 31 are respectively 1.59mm and 0.45mm, the distance between the branch lines is 6mm, and the distance between the terminal of each branch line and the center of a unit is 6 mm; the length and width of a thin groove in the cross bone-shaped coupling groove 41 are respectively 8.5mm and 0.5mm, the length and width of a terminal rectangular groove of a y-direction groove are respectively 5mm and 2.5mm, and the length and width of a terminal rectangular groove of an x-direction groove are respectively 5mm and 2 mm; the line widths of the trunk line and the branch line of the vertical polarization Y-shaped feeder line 51 are respectively 1.59mm and 0.45mm, the distance between the branch lines is 7mm, and the distance between the terminal of the branch line and the center of the cell is 6.5 mm.

The diameter of the metallized via 43 is 0.8mm, and a part of the metallized via surrounds the strip line feeder to form 21 × 18mm²With a spacing of 1.5mm, and another part surrounding the vertically polarized feedProbe 64, horizontally polarized feed probe 65, 2mm from the probe.

Two through holes 66 in the metal bottom plate are respectively arranged on the central lines in the x direction and the y direction, are 5mm away from the edge of the unit and have the diameter of 2.9 mm; the feed is a standard SMA connector with

inner cores

64, 65 each 1.27mm in diameter.

As can be seen from FIG. 2, the two polarizations of the antenna unit at E, H, D are scanned from 0 to 45 degrees, the standing wave at 3.6 to 4.2GHz is lower than 2.5, and the bandwidth is 15%; the simulation and actual measurement results in the limited array environment also verify the conclusion, see fig. 4.

As can be seen from fig. 5, the measured isolation of the dual-polarized port is above 23 dB.

As can be seen from fig. 6(a), the highest gain of the antenna unit is above 5dB, so that the aperture efficiency can be calculated to be above 80%, the cross polarization is below-20 dB, and the front-to-back ratio is above 12 dB; as can be seen from fig. 6(b) and (c), the array scans from 0 to 45 degrees, the sidelobe level is below-10 dB, and no grating lobe appears.

Claims

1. A dual polarized microstrip antenna element having wide angle broadband scanning capability, the antenna element comprising: the stacked patch layer, the dual-polarized feed layer and the metal bottom plate are sequentially stacked from top to bottom;

2. A dual polarized microstrip antenna element having wide angle broadband scanning capability according to claim 1 wherein said horizontally polarized feed line is a Y-shaped microstrip line along the Y-direction and said vertically polarized feed line is a Y-shaped stripline along the x-direction.

3. The dual polarized microstrip antenna element with wide-angle broadband scanning capability of claim 1 wherein each branch end of said cross-shaped coupling slot is provided with a rectangular slot with a width greater than and in communication with the cross-shaped coupling slot; the depth rectangular grooves of the cross-shaped coupling grooves are the same and equal to the thickness of the fourth PCB layer.

4. The dual polarized microstrip antenna element having a wide-angle broadband scanning capability of claim 1 wherein said metal base plate has two through holes disposed therein for connecting with a horizontally polarized feed probe and a vertically polarized feed probe, respectively.

5. The dual polarized microstrip antenna element having wide angle broadband scanning capability of claim 1 wherein the second stacked patch has a shape and size similar to the shape and size defined by a circle of metalized vias disposed in the dual polarized feed layer, and wherein the first stacked patch is disposed directly above the second stacked patch and has a larger area than the second stacked patch.

6. A dual polarized microstrip antenna element having wide angle broadband scanning capability according to claim 2 wherein said horizontally polarized feed line comprises two sections: the top point of the 1-type microstrip line part is connected with the middle point of the lower bottom edge of the U-type microstrip line part, and the bottom point of the 1-type microstrip line part is an input point.