A ka-band phased array antenna unit and antenna array

Abstract

The present invention discloses a ka-band phased array antenna unit and an antenna array. The antenna unit of the present invention is a three-layer structure arranged from top to bottom, wherein the first layer structure includes a first substrate and a first patch antenna arranged on the upper surface of the substrate, the second layer structure includes a second substrate, an air cavity is loaded on the second substrate, and the third layer structure includes a third substrate and a second patch antenna arranged on the upper surface of the substrate, the second patch antenna is connected with a first probe and a second probe for feeding, and the first substrate, the second substrate, and the third substrate are laminated as a whole based on a double-sided welding process. On the basis of meeting the isolation requirements, the present invention has a simpler structure and lower cost to solve the disadvantages of dual-coupled feeding and dual-probe feeding.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite communications, and in particular relates to a Ka-band phased array antenna unit and an antenna array. Background Art

[0002] With the rise of low-orbit Internet, Ka-band low-orbit Internet constellations and ground terminals have also developed rapidly. Low-orbit satellites are different from synchronous orbit satellites. Low-orbit satellites are in motion relative to the earth. Therefore, traditional ground terminals, such as parabolic and machine-scanned array antennas, are no longer applicable. Phased array antennas have advantages such as fast beam scanning and shaping and fast satellite switching, and will become mainstream in the field of low-orbit satellite ground terminals. At present, one of the factors restricting the development of phased array antennas is how to achieve low-cost design.

[0003] The overall performance of the phased array antenna is closely related to the characteristics of the selected antenna radiation unit, and it is also necessary to take into account the weight, volume, cost, low profile and other factors of the low-orbit satellite ground terminal. In summary, the microstrip patch antenna unit is not only small in size, light in weight, low in profile and low in cost, but also easy to integrate with the chip, which is very in line with the needs of actual application scenarios. However, microstrip patch antennas also have disadvantages, such as relatively narrow bandwidth and beam width. In the actual design process, more improvements are made around widening the bandwidth and beam width, reducing costs, etc.

[0004] The mainstream of Ka-band phased array antenna units adopts dual-linear polarization microstrip patch antennas. The mainstream form of widening bandwidth is a dual-patch stacking design, and the mainstream form of widening beam is a loaded grounded isolation grid design. There are two main feeding methods for antenna units on the market, dual-coupled feeding and dual-probe feeding. The dual-coupled feeding antenna unit in the prior art has the advantage of good isolation between the two ports, but the structure is complex, requiring the use of more PCB substrate layers, and the cost is relatively high. At the same time, the coupling gap has high requirements for the offset tolerance when the PCB is pressed together, which is easy to cause frequency deviation; the dual-probe feeding antenna unit in the prior art has the advantage of simple structure and fewer PCB substrate layers, but the isolation between the two ports is poor, which affects the antenna performance. Summary of the invention

[0005] In view of the above defects, the present invention provides a Ka-band phased array antenna unit and antenna array, which, on the basis of meeting the isolation requirements, have a simpler structure and lower cost, so as to solve the drawbacks of dual-coupled feeding and dual-probe feeding.

[0006] A Ka-band phased array antenna unit is a three-layer structure arranged from top to bottom, wherein the first layer structure comprises a first substrate and a first patch antenna arranged on the upper surface of the substrate, the second layer structure comprises a second substrate, an air cavity is loaded on the second substrate, the third layer structure comprises a third substrate and a second patch antenna arranged on the upper surface of the substrate, the second patch antenna is connected with a first probe and a second probe for feeding,

[0007] The first substrate, the second substrate and the third substrate are stacked into a whole based on a double-sided welding process.

[0008] Preferably, the second patch antenna is loaded with a spoiler slot, which is an axially symmetrical geometric figure symmetrical along the central axis, the side of the figure has a certain slope, and the slope increases along the probe port toward the opposite diagonal direction; the spoiler slot is placed along the diagonal of the second patch antenna, and the axis of symmetry coincides with the diagonal, and the ports of the first probe and the second probe are respectively located on both sides of the spoiler slot, and the isolation of the antenna is improved by adjusting the size of the gap and its relative position to the diagonal.

[0009] Preferably, the spoiler slit is a funnel-shaped spoiler slit or a Y-shaped spoiler slit.

[0010] Preferably, by adjusting the width and length of the spoiler slit, the current distribution of the two ports of the probe in the second patch antenna is changed, so that the crosstalk current between the two ports is minimized, thereby improving the dual-port isolation.

[0011] Preferably, the relative position of the spoiler slit on the diagonal line of the second patch antenna is adjusted to find the position that optimizes the impedance matching of the antenna.

[0012] Preferably, the first substrate, the second substrate, and the third substrate are all provided with isolation grids, and the isolation grids between the substrates serve as pads for double-sided welding. The structure composed of the isolation grids can also play a role in widening the antenna unit beam, killing two birds with one stone.

[0013] Preferably, the isolation grid is provided with a grounding hole.

[0014] The present invention also discloses a Ka-band phased array antenna array, comprising a plurality of the above-mentioned Ka-band phased array antenna units arranged along a straight line. To ensure that no grating lobes appear in the clearance area within the ±60° scanning range of the antenna, the antenna units are arranged at a spacing of 0.5±0.04 wavelengths. The antenna array comprises 256 antenna units, which are arranged in a 16*16 square array. The antenna adopts a probe feeding form.

[0015] Preferably, cross polarization is improved by rotating the antenna units, with the 2*2 antenna units in the array as the minimum periodic unit, the geometric center of the 2*2 antenna units as the coordinates and the first antenna unit as the reference, and the remaining antenna units are rotated 90° / 180° / 270° in sequence.

[0016] The beneficial effects of the present invention are:

[0017] (1) The present invention adopts a combination of loading air cavity and double-sided welding process to stack three layers of substrates together, which simplifies the structure and broadens the bandwidth, thereby improving the radiation efficiency of the antenna. Compared with the conventional loading air cavity + screw fixing form, the consistency is better;

[0018] (2) The present invention improves the isolation between the two probes by loading a funnel-shaped or Y-shaped spoiler gap on the second patch antenna without increasing the antenna cost. The present invention is simple and effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below.

[0020] Figure 1 is an exploded diagram of a Ka-band phased array antenna unit according to an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of a Ka-band phased array antenna unit loaded with a funnel-shaped spoiler slot according to an embodiment of the present invention;

[0022] Figure 3 Schematic diagram of a Ka-band phased array antenna unit loaded with a Y-shaped spoiler slot according to an embodiment of the present invention;

[0023] Figure 4 It is a schematic diagram of a 256-element phased array receiving antenna array according to an embodiment of the present invention;

[0024] Figure 5 is a side view of a Ka-band phased array antenna unit according to an embodiment of the present invention;

[0025] Figure 6 is a comparison diagram of a loaded funnel-shaped spoiler slit and an unloaded funnel-shaped spoiler slit according to an embodiment of the present invention;

[0026] Figure 7 1 is a comparison diagram of a loaded air cavity and an unloaded air cavity according to an embodiment of the present invention.

[0027] Figure numerals: 1-first patch antenna, 2-first ground isolation grid, 3-first substrate, 4-first grounding hole, 5-second ground isolation grid, 6-third ground isolation grid, 7-second substrate, 8-second grounding hole, 9-fourth ground isolation grid, 10-fifth ground isolation grid, 11-third grounding hole, 12-third substrate, 13-GND, 14-air cavity, 15-funnel-shaped spoiler gap, 16-second patch antenna, 17-first probe, 18-second probe, 19-first solder paste, 20-second solder paste. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0029] The embodiment of the present invention provides a ka-band phased array antenna unit, combined with Figure 1 Exploded diagram, the antenna unit adopts dual polarization and has a three-layer structure:

[0030] The first layer structure includes a first substrate 3, a first patch antenna 1, and a double-sided grounded isolation grid including a first grounded isolation grid 2 and a second grounded isolation grid 5, which are respectively arranged on the upper and lower surfaces of the first substrate 3, and the first grounded isolation grid 2 and the second grounded isolation grid 5 are provided with a first grounding hole 4 penetrating therethrough, and the isolation grid with the grounding hole has the function of widening the beam width of the antenna unit. The first patch antenna 1 is applied to the upper surface of the first substrate 3. The patch used in this embodiment is a square patch as a whole, and bosses are loaded in four directions to increase the degree of freedom of the first patch antenna 1 and facilitate subsequent impedance matching.

[0031] The second layer structure includes a second substrate 7, a second patch antenna 16 and a double-sided ground isolation grid including a third ground isolation grid 6 and a fourth ground isolation grid 9, which are respectively arranged on the upper and lower surfaces of the second substrate 7, and the third ground isolation grid 6 and the fourth ground isolation grid 9 are provided with a second grounding hole 8 that penetrates through. An air cavity 14 is slotted inside the second substrate 7, which is a rectangular air cavity in this embodiment. The air cavity 14 is 1 / 4 wavelength away from the edge of the second substrate 7, and the main radiation direction is 1 / 4-1 / 2 wavelength, which is about 0.0762 wavelength in this embodiment. The advantage of loading an air cavity is a wider bandwidth, but the cost is that the substrates cannot be pressed together through conventional PCB processing technology.

[0032] The third layer structure includes a third substrate 12, a second patch antenna 16, a fifth ground isolation grid 10, a first probe 17 and a second probe 18. The second patch antenna 16 and the fifth ground isolation grid 10 are applied to the upper surface of the third substrate 12, the lower surface of the third substrate 12 is GND13, and the fifth ground isolation grid 10 is provided with a third grounding hole 11. The first probe 17 and the second probe 18 are directly connected to the second patch antenna 16 for feeding. Compared with the dual-coupled feeding form in the prior art, the coaxial probe feeding structure disclosed in this embodiment is simple. Compared with the dual-probe feeding in the prior art, the antenna in this embodiment has better bandwidth performance by loading an air cavity and a dual-patch combination mode. Furthermore, in order to solve the problem of poor isolation of the dual-probe feeding form, a spoiler slot is loaded at an appropriate diagonal position of the second patch antenna 16.

[0033] The spoiler slit is an axisymmetric geometric figure symmetrical along the central axis, and the side of the figure has a certain slope, and the slope increases from the probe port to the opposite diagonal direction, that is, the spoiler slit is in an open shape from the probe port to the opposite diagonal direction of the second patch antenna. In this embodiment, the spoiler slit is preferably a funnel-shaped spoiler slit 15 or a Y-shaped spoiler slit. The funnel-shaped spoiler slit 15 is as shown in FIG. Figure 2 As shown in the figure, the upper and lower lines of the gap are parallel, and two vertical downward lines are drawn from both ends of the upper line, then narrowed inward and connected to the two ends of the lower line of the gap, forming a plane funnel-shaped geometric shape as a whole; the Y-shaped gap is as shown in the figure. Figure 3 As shown, it is similar to the funnel-shaped gap, but different from the funnel-shaped gap, a rectangular notch is cut in the center of the funnel-shaped top. The funnel-shaped spoiler slit 15 or the Y-shaped spoiler slit is an axisymmetric slit. When set, the symmetry axis of the spoiler slit coincides with the diagonal of the second patch antenna 16. The two ports of the first probe and the second probe are respectively located on both sides of the spoiler slit. By adjusting the size of the spoiler (i.e., the width and length of the spoiler slit), the current distribution of the two ports of the probe in the second patch antenna is changed, so that the crosstalk current between the two ports is minimized, and the dual-port isolation is improved. Adjusting the width and length of the funnel-shaped slit will cause the impedance matching of the antenna to deteriorate and the frequency deviation. To further solve the above problems, the spoiler slit is adjusted to move on the diagonal line to find the appropriate position to optimize the impedance matching of the antenna and correct the frequency deviation. The optimal impedance matching is achieved while improving the isolation.

[0034] The three-layer substrate is stacked as a whole based on the double-sided welding process, such as Figure 5As shown. The isolation grid has an improvement effect on the beam width, and at the same time, the isolation grids in contact between the substrates, namely the second ground isolation grid 5, the third ground isolation grid 6, the fourth ground isolation grid 9, and the fifth ground isolation grid 10 can be used as double-sided solder pads. The second ground isolation grid 5 and the third ground isolation grid 6 are soldered between the first substrate 3 and the second substrate 7 using the first solder paste 19, and the fourth ground isolation grid 9 and the fifth ground isolation grid 10 are soldered between the second substrate 7 and the third substrate 12 using the second solder paste 20, so that the loading air cavity 14 ( Figure 5 As shown). The double-sided welding process uses high-temperature welding, which is conducive to the subsequent normal-temperature welding of the chip of the phased array antenna. That is, the subsequent chip welding process will not affect the previous double-sided welding process; at the same time, the ground isolation grid required for double-sided welding can widen the beam width of the antenna, killing two birds with one stone.

[0035] The antenna unit model of the present invention not only has good electrical performance and excellent isolation, but also makes the antenna solution structure the simplest and PCB occupies fewer layers to achieve the effect of reducing costs. It is suitable for Ka-band phased array ground terminals and has great engineering application value. Example 2

[0036] The present invention also discloses a phased array receiving antenna array surface. By using the above-mentioned Ka-band phased array antenna unit, a 256-unit phased array receiving antenna array surface is designed, and the operating frequency is 17.7GHz-21.2GHz (such as Figure 4 As shown). To ensure that there are no grating lobes in the clearance area within the ±60° scanning range of the antenna, the antenna units are arranged at a spacing of about 0.5 wavelengths. The antenna array consists of 256 antenna units in a 16*16 square array. This array form is conducive to modularization. For example, to upgrade to a 1024-unit antenna array, only 4 256-unit arrays need to be spliced ​​in a 2*2 manner. The antenna adopts a probe feeding form, which is convenient for welding with RF multi-function chips and easy to integrate. The phased array receiving antenna array has a total of 3 substrates, which are fixed together by a combination of loading air cavity + double-sided welding process. A funnel-shaped spoiler seam 15 is loaded at the second patch antenna position of each antenna unit to improve antenna isolation. As shown Figure 6 As shown, the horizontal axis is frequency, and the vertical axis is S21. By comparing the dual-probe isolation S21 when the funnel-shaped spoiler slot is loaded and not loaded, it can be seen that the isolation is significantly improved after the funnel-shaped spoiler slot 15 is loaded. Of course, loading the funnel-shaped spoiler slot 15 will worsen the cross-polarization. When forming an array, the cross-polarization can be improved by rotating the antenna units. That is, the 2*2 antenna units in the array are used as the minimum periodic unit, and the geometric center of the 2*2 antenna units is used as the coordinate and the first antenna unit is used as a reference. The remaining antenna units are rotated 90° / 180° / 270° in sequence. Figure 7As shown, the horizontal axis is frequency, and the vertical axis is S11. By comparing the S11 before and after loading the air cavity, it can be seen that loading the air cavity is of great help to the bandwidth. After loading the air cavity, the antenna has a higher tolerance to the frequency deviation caused by actual processing. At the same time, the double-sided welding process has higher positioning accuracy than the screw-fixed installation, which improves the consistency of the antenna.

[0037] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A Ka-band phased array antenna unit, characterized in that: It is a three-layer structure set up from top to bottom. The first layer structure includes a first substrate and a first patch antenna arranged on the upper surface of the substrate. The second layer structure includes a second substrate, on which an air cavity is loaded, The third layer structure includes a third substrate and a second patch antenna arranged on the upper surface of the substrate, the second patch antenna is connected to a first probe and a second probe for feeding, the second patch antenna is loaded with a spoiler slot, the spoiler slot is an axially symmetrical geometric figure symmetrical along the central axis, and is funnel-shaped or Y-shaped, the side of the figure has a certain slope, and the slope increases along the probe port to the opposite diagonal direction; the spoiler slot is placed along the diagonal of the second patch antenna, the symmetry axis coincides with the diagonal, the ports of the first probe and the second probe are respectively located on both sides of the spoiler slot, and the isolation of the antenna is improved by adjusting the size of the slot and the relative position to the diagonal. The first substrate, the second substrate and the third substrate are stacked into a whole based on a double-sided welding process.

2. The Ka-band phased array antenna unit according to claim 1, characterized in that: By adjusting the width and length of the spoiler slit, the current distribution of the two ports of the probe in the second patch antenna is changed, so that the crosstalk current between the two ports is minimized, and the dual-port isolation is improved.

3. The Ka-band phased array antenna unit according to claim 2, characterized in that: The relative position of the spoiler slit on the diagonal line of the second patch antenna is adjusted to find the position that optimizes the impedance matching of the antenna.

4. The Ka-band phased array antenna unit according to claim 1, characterized in that: Isolation grids are arranged around the first substrate, the second substrate and the third substrate, and the isolation grids between the substrates serve as pads for double-sided welding.

5. The Ka-band phased array antenna unit according to claim 4, characterized in that: The isolation grid is provided with a grounding hole.

6. A Ka-band phased array antenna array, characterized in that: It comprises a plurality of Ka-band phased array antenna units as claimed in any one of claims 1 to 5 arranged in a straight line, the antenna array comprises 256 antenna units, the antenna units are arranged at a spacing of 0.5±0.04 wavelengths, and the array is arranged in a 16*16 square array form; the antenna adopts a probe feeding form.

7. The Ka-band phased array antenna array according to claim 6, characterized in that: Cross polarization is improved by rotating the antenna units. The 2*2 antenna units in the array are used as the minimum periodic unit. The geometric center of the 2*2 antenna units is used as the coordinate and the first antenna unit is used as the reference. The remaining antenna units are rotated 90°, 180° and 270° in sequence.

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