An ultra-wideband scalable millimeter wave antenna unit and antenna array

Abstract

The present invention discloses an ultra-wideband expandable millimeter wave antenna unit, comprising: a first ground plane, a second ground plane, a coplanar feed transmission line and a microstrip transmission line located in a first plane, a third ground plane located in a second plane, and a main radiating unit, the first ground plane and the second ground plane are located on both sides of the coplanar feed transmission line, the microstrip transmission line and the coplanar feed transmission line extend outward from a side away from the first ground plane and the second ground plane, the first ground plane and the third ground plane are connected by a first via hole, the second ground plane and the third ground plane are connected by a second via hole, the third ground plane has a slot, the projection area of ​​the slot on the first plane covers one end of the microstrip transmission line away from the coplanar feed transmission line, the main radiating unit is located on the other side of the third ground plane relative to the first plane, and the projection area of ​​the main radiating unit on the third ground plane covers the slot area. The millimeter wave antenna unit can achieve higher gain by expanding to form an antenna array.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to an ultra-wideband expandable millimeter wave antenna unit and an antenna array. Background Art

[0002] In recent years, with the rapid development of wireless communication technology, the popularization of various electronic devices, and the promotion of millimeter-wave gesture recognition radars and millimeter-wave vehicle-mounted radars, people have put forward higher requirements for the quality of wireless communication. Faster transmission speeds and better transmission bandwidths mean that the communication frequency band needs to continue to develop towards broadband and high frequency, which has promoted the research on high-frequency broadband antennas. The advantages of millimeter-wave antennas such as short wavelengths, fast transmission speeds, and good propagation characteristics have made them enter the field of vision of most people.

[0003] Traditional millimeter wave antennas are generally implemented using waveguide structures. Compared with planar patch antennas, waveguide structures are relatively complex and expensive, and are not conducive to integration. Therefore, research on miniaturized millimeter wave microstrip antennas is inevitable and necessary. In millimeter wave wireless communication systems, antennas are energy conversion devices for transmitting and receiving signals. The performance of antennas seriously affects the performance and other characteristics of wireless communication systems. Waveguide slot antennas commonly used in modern radar systems have slots on the waveguide to form a radiation slot array to improve radiation performance. However, this type of antenna is large in size, which is not conducive to system integration and miniaturization. The requirements in actual production and processing are getting higher and higher. The slot width of the waveguide slot antenna is generally less than 1mm, and the depth and inclination angle are different. At the same time, the structure of the antenna array is compact, so the processing and assembly process needs to overcome multiple technical difficulties at the same time, which greatly increases the cost.

[0004] If the traditional microstrip patch antenna structure is used, although it has the advantages of simple structure and low cost, the impedance bandwidth of the conventional microstrip patch antenna is very narrow (about 5%), which is difficult to meet the broadband requirements of the millimeter wave band, especially in the 60G, 77G and higher frequency bands. The conventional microstrip line-fed millimeter wave antenna has the disadvantages of large microstrip line radiation loss, large dispersion, poor isolation between the feed line and the radiating unit, and a large influence of the substrate thickness on the characteristic impedance. Summary of the invention

[0005] In view of the above problems, the present invention provides a millimeter wave antenna unit with ultra-wide impedance bandwidth, low processing cost and simple structure.

[0006] The present application discloses an ultra-wideband scalable millimeter wave antenna unit, comprising:

[0007] A first ground plane, a second ground plane, a coplanar feeding transmission line and a microstrip transmission line located in a first plane, wherein the first ground plane and the second ground plane are located on both sides of the coplanar feeding transmission line respectively, and the microstrip transmission line is connected to the coplanar feeding transmission line and extends to a side away from the first ground plane and the second ground plane;

[0008] a third ground plane located in a second plane parallel to the first plane, the first ground plane and the third ground plane being connected via a row of first vias close to the coplanar feed transmission line, the second ground plane and the third ground plane being connected via a row of second vias close to the coplanar feed transmission line, the third ground plane having a slot, the projection area of ​​the slot on the first plane covering an end of the microstrip transmission line away from the coplanar feed transmission line;

[0009] A main radiation unit is located on the other side of the third ground plane relative to the first plane, and a projection area of ​​the main radiation unit on the third ground plane covers the slot.

[0010] Preferably, the main radiation unit is formed by stacking multiple layers of metal patches, and a dielectric substrate is provided between adjacent layers of metal patches.

[0011] Preferably, the multi-layer metal patch is respectively located on the plane where each copper clad layer of the printed circuit board is located.

[0012] Preferably, the main radiation unit includes 4 layers of metal patches.

[0013] Preferably, the shape of each layer of metal patch is rectangular, circular, trapezoidal or triangular.

[0014] Preferably, in the row of first via holes and the row of second via holes, the hole spacing between two adjacent via holes in each row is less than 1 / 4 wavelength of the operating frequency.

[0015] Preferably, a first dielectric substrate is provided between the first ground plane, the second ground plane and the third ground plane, and a second dielectric substrate is provided between the third ground plane and the main radiation unit.

[0016] Preferably, the shape of the slot is rectangular, H-shaped, F-shaped or U-shaped.

[0017] Preferably, the first plane and the second plane are respectively planes where the copper cladding layers of the printed circuit board are located.

[0018] The present application also discloses an antenna array, comprising an antenna array composed of multiple millimeter wave antenna units as described above.

[0019] Compared with the prior art, the present invention adopts the grounded coplanar waveguide structure feeding, which has the advantages of low loss, small dispersion, good isolation, and little influence of substrate thickness on characteristic impedance. At the same time, the microstrip line slot coupling feeding structure and multi-layer patch coupling radiation structure can not only effectively expand the bandwidth of the antenna, but also obtain good directional characteristics, and can design ultra-wideband, low-cost, easy to integrate and produce directional millimeter wave antennas. The relative bandwidth of the antenna unit in the high-frequency millimeter wave band can reach more than 30%. The antenna unit can be expanded through the array to form an antenna array to further improve the antenna gain.

[0020] The dielectric substrate and radiation patch of the antenna adopt a multi-layer design, which is suitable for processing on a PCB multi-layer board. Grounded coplanar waveguide is used for feeding, and the grounded coplanar waveguide transmission line can be realized with only metallized through holes. The ground of the transmission line and the antenna does not need to use blind holes, avoiding the difficulty and high cost of blind hole processing. The overall structure is easy to use PCB processing and can be widely used in the design of millimeter wave antenna units and millimeter wave array antennas. In actual use, by designing the material and thickness of the dielectric substrate, the shape and size of the patch, the shape and size of the slot on the ground plane, and the length of the microstrip line, an impedance matching bandwidth of more than 25GHz can be achieved. The relative bandwidth reaches more than 30% and the ultra-wideband directional millimeter wave antenna unit suitable for PCB processing has the advantages of ultra-wideband, planarization, low cost, and easy mass production. The millimeter wave antenna unit can achieve higher gain by expanding to form an antenna array. It has high practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a top view schematic diagram of the top surface of an ultra-wideband scalable millimeter wave antenna unit structure of the present invention.

[0022] Figure 2 It is a top view schematic diagram of the bottom surface of an ultra-wideband scalable millimeter wave antenna unit structure of the present invention.

[0023] Figure 3 It is a side schematic diagram of an ultra-wideband scalable millimeter wave antenna unit structure of the present invention.

[0024] Figure 4 It is a 3D schematic diagram of a structural side top view of an embodiment of the present invention.

[0025] Figure 5 It is a 3D schematic diagram of the structure of an embodiment of the present invention when viewed from the side.

[0026] Figure 6 1 is a diagram of the S11 impedance bandwidth of an embodiment of the present invention.

[0027] Figure 7 It is the 2D radiation pattern of the antenna at 62 GHz according to an embodiment of the present invention.

[0028] Figure 8 It is the 3D radiation pattern of the antenna of one embodiment of the present invention at 62 GHz.

[0029] Fig. 9 It is the 2D radiation pattern of the antenna of one embodiment of the present invention at 79 GHz.

[0030] Fig.10 It is the 3D radiation pattern of the antenna of one embodiment of the present invention at 79 GHz. DETAILED DESCRIPTION

[0031] The following is a further description of the specific implementation of the present invention in conjunction with the drawings of the specification, so that the technical solution and its beneficial effects of the present invention are clearer and more specific. The following description of the embodiments with reference to the drawings is only exemplary and is intended to explain the present invention, but cannot be understood as limiting the present invention.

[0032] It should be noted that in the description of the present invention, directional words such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating directions and positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific protection scope of the present invention. In the description of the present invention, if there are numerical values ​​of length, width, thickness, etc., they are only for the purpose of describing the present invention and simplifying the description, and cannot be understood as limiting the specific protection scope of the present invention.

[0033] In the present invention, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. Therefore, the terms "first", "second", etc. may explicitly or implicitly include one or more of the features, and in the description of the present invention, "at least" means one or more than one, unless otherwise clearly and specifically defined.

[0034] In the present invention, unless otherwise specified and limited, the terms "assemble", "connect", "connection" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can also be a mechanical connection; it can be directly connected, or it can be connected through an intermediate medium, or the two elements can be internally connected. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] refer to Figure 1 and Figure 2 As shown, one embodiment of the present application discloses an ultra-wideband scalable millimeter wave antenna unit. The antenna unit of this embodiment includes a first ground plane 1, a second ground plane 2, a coplanar feed transmission line 4, a microstrip transmission line 5 located in a first plane, a third ground plane 3 located in the second plane, a slot 9 located on the third ground plane, a metallized via 6 connecting the first ground plane 1 and the third ground plane 3, a metallized via 7 connecting the second ground plane 2 and the third ground plane 3, and a main radiation unit 8 of a multi-layer metal patch. The antenna unit has a total of six layers.

[0036] The first plane and the second plane are respectively the planes where the copper clad layer of the printed circuit board is located. The planes where the patches of each layer in the main radiation unit 8 are located are also respectively the planes where the copper clad layer of the printed circuit board is located. In this embodiment, the copper thickness of all the copper clad layers is 1.4 mil, i.e., 1 oz.

[0037] In the first plane, the first ground plane 1 and the second ground plane 2 are respectively located on both sides of the coplanar feed transmission line 4. In this embodiment, the first ground plane 1, the second ground plane 2 and the coplanar feed transmission line 4 are located on the same copper clad layer in the PCB board, namely the first plane. The coplanar feed transmission line 4 is connected to the inner conductor of the feed connector, and the first ground plane 1 and the second ground plane 2 are connected to the outer conductor of the feed connector. The line width of the coplanar feed transmission line 4 is 7.87 mil, and the spacing between the first ground plane 1 and the second ground plane 2 on both sides is 8 mil. After simulation calculation, the transmission line impedance of this line width size is 50 ohms within the antenna working frequency band and under the condition of the dielectric substrate, which can achieve good matching.

[0038] Furthermore, the microstrip transmission line 5 and the coplanar feeding transmission line 4 are on the same copper clad layer in the PCB board, i.e., the first plane, and are connected to the coplanar feeding transmission line 4. The microstrip transmission line 5 is connected to the coplanar feeding transmission line 4 and extends to a side away from the first ground plane 1 and the second ground plane 2. The line width of the microstrip transmission line 5 is 7.87 mil, which is consistent with the line width of the grounded coplanar transmission line.

[0039] In the second plane, the third ground plane 3 has a slot 9 and a main radiating element 8, and the projection area of ​​the slot 9 on the first plane covers the end of the microstrip transmission line 5 away from the coplanar feeding transmission line 4. The slot 9 on the third ground plane 3 is formed by digging a slot on the metal copper clad layer where the third ground plane 3 is located. In one embodiment, the slot 9 is rectangular, and the length of the rectangle is 0.8 mm and the width is 0.42 mm. The length of the projection area of ​​the slot 9 on the first plane is perpendicular to the extension direction of the microstrip transmission line and is greater than the width of the microstrip transmission line. The slot 9 and the microstrip transmission line 5 form a gap coupling structure. The radiating element 8 is located on the other side of the third ground plane 3 relative to the first plane, and the projection area of ​​the main radiating element 8 on the third ground plane 3 covers the slot 9.

[0040] In other embodiments, the shape of the slot is not limited to a rectangle, and may be other shapes such as a U-shape, an H-shape, an F-shape, etc. The number of the slots is not limited to one, and may be multiple. All of the above should be regarded as a variation of the present invention and should be included in the protection scope of the present invention.

[0041] refer to Figure 2 and Figure 3 As shown, the first ground plane 1 and the third ground plane 3 are connected through a row of first vias 6 close to the coplanar feed transmission line, and the second ground plane 2 and the third ground plane 3 are connected through a row of second vias 7 close to the coplanar feed transmission line. There is a first dielectric substrate 31 between the first ground plane 1 and the second ground plane 2 and the third ground plane 3. The first dielectric substrate 31 is made of RO4350B, with a dielectric constant of 3.48, a loss tangent of 0.0037, and a thickness of 4 mils. The hole spacing between adjacent first vias 6 and adjacent second vias 7 in a row of first vias 6 and a row of second vias 7 is less than 1 / 4 wavelength of the operating frequency. In one embodiment, the diameter of the metallized vias 6 and 7 is 5.9 mil, and the spacing between two adjacent vias in each row is 18 mil.

[0042] The main radiation unit 8 is formed by stacking multiple layers of metal patches, and there is a dielectric substrate between the metal patches of adjacent layers. The multi-layer metal patch main radiation unit 8 includes a first patch 21, a second patch 22, a third patch 23, a fourth patch 24, ..., and an Nth patch 2n. There is a dielectric substrate 41 between the first patch 21 and the second patch 22, a dielectric substrate 42 between the second patch 22 and the third patch 23, a dielectric substrate 43 between the third patch 23 and the fourth patch 24, ..., and a dielectric substrate 4(n-1) between the N-1th patch and the Nth patch 2n. The multi-layer patch main radiation unit 8 is located on the other side of the third ground plane 3 relative to the microstrip transmission line 5, and there is a second dielectric substrate 32 between the first patch 21 and the third ground plane 3; the projection area of ​​the multi-layer patch main radiation unit 8 on the third ground plane 3 needs to cover the slot 9 area on the third ground plane. The main radiation unit 8 and the slot 9 form a gap coupling structure.

[0043] like Figure 4 and Figure 5As shown, the main radiation unit 8 of this embodiment may include four layers of metal patches, which are designed to overlap with equal-area projections, and are respectively the first patch 21, the second patch 22, the third patch 23 and the fourth patch 23 in the order from inside to outside in the direction perpendicular to the second plane with respect to the third ground plane 3. The shape of each patch is, for example, a rectangle, and the length of the patch is 1.65 mm and the width is 0.81 mm. There is a dielectric substrate 41, 42, 43 between the first patch 21 and the second patch 22, between the second patch 22 and the third patch 23, and between the third patch 23 and the fourth patch 24. The material of the substrates 41, 42, 43 is RO4350B, with a dielectric constant of 3.48, a loss tangent of 0.0037, and a thickness of 4 mil. The main radiation unit 8 of the multilayer patch is located on the other side of the third ground plane 3 relative to the microstrip transmission line 5. There is a second dielectric substrate 32 between the first patch 21 and the third ground plane 3. The material of the second dielectric substrate 32 is RO4350B, with a dielectric constant of 3.48, a loss tangent of 0.0037, and a thickness of 4 mil. The projection area of ​​the main radiation unit 8 of the multilayer patch on the third ground plane 3 needs to cover the slot 9 area on the third ground plane. The first patch, the second patch, the third patch, and the fourth patch in the main radiation unit 8 of the multilayer patch in this embodiment form a coupling structure.

[0044] In other embodiments, for the multi-layer patch in the ultra-wideband scalable millimeter wave antenna unit, the shape of the patch is not limited to a rectangle, but may also be other shapes such as a circle, a trapezoid, a triangle, or other variations of these shapes. The size of each layer of the multi-layer patch is not limited to being completely consistent, that is, the projections completely overlap, but may also be in a gradual form, that is, the projection areas do not overlap. All of the above should be regarded as a variation of the present invention and should be included in the protection scope of the present invention.

[0045] The first ground plane 1, the second ground plane 2, a row of metallized vias 6 connecting the first ground plane 1 and the third ground plane 3, a row of metallized vias 7 connecting the second ground plane 2 and the third ground plane 3, the coplanar feeding transmission line 4 and the first dielectric substrate 31 of this embodiment together form a grounded coplanar waveguide structure for transmitting the fed RF signal. This embodiment has the advantages of low loss, low coupling, low radiation leakage, etc., and can reduce the influence of the feed line on the antenna pattern and gain.

[0046] Figure 6 This is an impedance bandwidth diagram of antenna S11 of an embodiment. As can be seen from the figure, the -10dB impedance bandwidth can reach 26.4GHz from 56.4GHz to 82.8GHz, and the relative bandwidth can reach 38%, which is an ultra-wideband antenna. It can fully cover the two typical application frequency bands of millimeter wave bands 60G and 77G / 79G.

[0047] Figure 7is the 2D radiation pattern of this embodiment at 62 GHz, Figure 8 This is the 3D radiation pattern of this embodiment at 62 GHz, and the maximum gain of the antenna at this frequency is 7.2 dB.

[0048] Fig. 9 is the 2D radiation pattern of this embodiment at 79 GHz, Fig.10 This is the 3D radiation pattern of this embodiment at 79 GHz, and the maximum gain of the antenna at this frequency is 7.7 dB.

[0049] During actual debugging of the antenna unit of the present application, the resonant frequency and impedance bandwidth of the antenna can be adjusted by adjusting the size of the multi-layer patch. The impedance bandwidth of the antenna can be adjusted by adjusting the size, position and shape of the slot, and the length of the microstrip line. The resonant frequency and impedance bandwidth of the antenna unit can be adjusted by changing the material and thickness of the different layers of dielectrics and the thickness of the copper cladding. The impedance bandwidth and gain of the antenna can be fine-tuned by increasing or decreasing the number of layers of the patch. The antenna gain and directivity can be improved by adding a metal reflective backplane on one side of the microstrip line. The antenna gain can be improved by adding parasitics around the top patch.

[0050] Furthermore, the present application also discloses an antenna array, comprising an antenna array composed of multiple millimeter wave antenna units as described above.

[0051] In summary, the antenna of this embodiment is an ultra-wideband expandable millimeter-wave multi-layer patch antenna that can be processed using PCB multi-layer board technology. The antenna unit has the characteristics of ultra-wide impedance bandwidth, low processing cost and simple structure, and can further improve the antenna gain by forming an antenna array through array expansion. It has high practical value.

[0052] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts, so the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention, and if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and variations.

Claims

1. An ultra-wideband scalable millimeter wave antenna unit, characterized in that: include: A first ground plane (1), a second ground plane (2), a coplanar feeding transmission line (4) and a microstrip transmission line (5) located in a first plane, wherein the first ground plane (1) and the second ground plane (2) are located on both sides of the coplanar feeding transmission line (4), respectively, and the microstrip transmission line (5) is connected to the coplanar feeding transmission line (4) and extends to a side away from the first ground plane (1) and the second ground plane (2); A third ground plane (3) located in a second plane parallel to the first plane, the first ground plane (1) and the third ground plane (3) are connected via a row of first via holes (6) close to the coplanar feeding transmission line (4), the second ground plane (2) and the third ground plane (3) are connected via a row of second via holes (7) close to the coplanar feeding transmission line (4), the third ground plane (3) has a slot (9), and the projection area of ​​the slot (9) on the first plane covers the end of the microstrip transmission line (5) away from the coplanar feeding transmission line (4); A main radiation unit (8) is located on the other side of the third ground plane (3) relative to the first plane, and a projection area of ​​the main radiation unit (8) on the third ground plane (3) covers the slot (9).

2. The ultra-wideband scalable millimeter wave antenna unit according to claim 1, characterized in that: The main radiation unit (8) is formed by stacking multiple layers of metal patches (21, 22, 23, 24), and a dielectric substrate (41, 42, 43) is provided between adjacent layers of metal patches.

3. The ultra-wideband scalable millimeter wave antenna unit according to claim 2, characterized in that: The multi-layer metal patches (21, 22, 23, 24) are respectively located on the planes where the copper-clad layers of the printed circuit board are located.

4. The ultra-wideband scalable millimeter wave antenna unit according to claim 2, characterized in that: The main radiation unit (8) comprises four layers of metal patches (21, 22, 23, 24).

5. The ultra-wideband scalable millimeter wave antenna unit according to claim 2, characterized in that: The shape of each layer of metal patches (21, 22, 23, 24) is rectangular, circular, trapezoidal or triangular.

6. The ultra-wideband scalable millimeter wave antenna unit according to claim 1, characterized in that: In the row of first via holes (6) and the row of second via holes (7), the hole spacing between two adjacent via holes in each row is less than 1 / 4 wavelength of the operating frequency.

7. The ultra-wideband scalable millimeter wave antenna unit according to claim 1, characterized in that: A first dielectric substrate (31) is provided between the first ground plane (1), the second ground plane (2) and the third ground plane (3), and a second dielectric substrate (32) is provided between the third ground plane (3) and the main radiation unit (8).

8. The ultra-wideband scalable millimeter wave antenna unit according to claim 1, characterized in that: The shape of the slot (9) is rectangular, H-shaped, F-shaped or U-shaped.

9. The ultra-wideband scalable millimeter wave antenna unit according to claim 1, characterized in that: The first plane and the second plane are respectively planes where the copper cladding layers of the printed circuit board are located.

10. An antenna array, characterized in that: An antenna array comprising a plurality of millimeter wave antenna units as described in any one of claims 1-9.

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