Integrated Substrate Gap Waveguide Four-Arm Circularly Polarized Antenna

Abstract

The present invention discloses an integrated substrate gap waveguide four-arm circularly polarized antenna, which includes an upper dielectric substrate, a lower dielectric substrate, and a spacer dielectric substrate; a first copper-clad layer is printed on the upper surface of the upper dielectric substrate, and a slit is provided on the first copper-clad layer. A feeding microstrip line, a quarter-wavelength impedance transformer, and a three-quarter-wavelength impedance matching line are sequentially connected and printed on the lower surface of the upper dielectric substrate. The impedance matching line is bent into a ring shape from the outside to the inside, and four antenna arms that are perpendicular to each other and spaced by a quarter wavelength are provided on the impedance matching line. An impedance matching patch that is disposed opposite to and has the same size as the impedance transformer, and a circular patch that is disposed opposite to and has the same size as the impedance matching line are provided in the slit; a second copper-clad layer is printed on the lower surface of the lower dielectric substrate, and circular metal patches arranged periodically are printed on the upper surface of the lower dielectric substrate, and metal vias are provided on each circular metal patch. The present invention can simplify the antenna structure, improve the antenna gain and bandwidth, and improve the axial ratio bandwidth performance.

Description

Technical Field

[0001] The invention relates to the technical field of antennas, in particular to an integrated substrate gap waveguide four-arm circularly polarized antenna. Background Art

[0002] Circularly polarized antennas are widely used in many different scenarios such as navigation satellites, radars, and mobile communications due to their good compatibility and anti-interference capabilities. At present, millimeter-wave circularly polarized antennas are roughly divided into microstrip circularly polarized antennas, metal rectangular waveguide (RW) circularly polarized antennas, and substrate integrated waveguide (SIW) circularly polarized antennas. At present, there are some problems with traditional millimeter-wave circularly polarized antennas, such as: pure metal structures are difficult to manufacture in the millimeter-wave band, and the electromagnetic shielding performance of substrate integrated waveguides (SIW) is not strong and the structure is complex.

[0003] In recent years, the integrated substrate gap waveguide (ISGW) antenna has been proposed. This antenna is based on a multi-layer PCB board and is divided into two structures: the ridged ISGW and the microstrip ISGW. The ridged ISGW is generally composed of two layers of PCB. The outer surface of the upper PCB is fully copper-clad to form a perfect electric conductor (PEC). The lower PCB is printed with a microstrip line. The microstrip line has a series of metallized vias connected to the metal ground below to form a ridge-like structure. The two sides of the microstrip line are periodic mushroom structures to form a perfect magnetic conductor (PMC). Due to the formation of EBG between PEC and PMC, electromagnetic waves (quasi-TEM waves) can only propagate along the microstrip line. However, since the microstrip line and the mushroom structure in the ridged ISGW are on the same PCB board, the microstrip line will be restricted by the mushroom structure and is not convenient for routing, which has limitations in practical applications.

[0004] ISGW is composed of three layers of PCB boards. The outer side of the upper PCB board is fully covered with copper to form PEC, and the inner side is printed with microstrip lines. The bottom PCB board is fully printed with mushroom-shaped periodic structures to form PMC. An intermediate dielectric board is inserted between the upper and bottom layers to separate the upper and bottom layers. Due to the separation of the intermediate layer, the microstrip line layout is flexible and there is no need to worry about being restricted by the mushroom-shaped periodic structure. When this ISGW is working, the quasi-TEM wave will propagate along the microstrip line in the dielectric substrate between the microstrip line and PEC. This working mode is very similar to the microstrip line buried in the dielectric. Similarly, EBG will be generated between PEC and PMC to prevent the wave from propagating in other directions to ensure the propagation of the quasi-TEM wave along the microstrip line. Summary of the invention

[0005] The main technical problem solved by the present invention is to provide an integrated substrate gap waveguide four-arm circularly polarized antenna, which can simplify the antenna structure, increase the antenna gain and bandwidth, and improve the axial ratio bandwidth performance.

[0006] To solve the above technical problems, a technical solution adopted by the present invention is: to provide an integrated substrate gap waveguide four-arm circularly polarized antenna, which includes an upper dielectric plate (1), a lower dielectric plate (3), and a spacer dielectric plate (2) disposed between the upper dielectric plate (1) and the lower dielectric plate (3); a first copper-clad layer (11) is printed on the upper surface of the upper dielectric plate (1), a slit (12) is provided on the first copper-clad layer (11), a feeding microstrip line (13), a quarter-wavelength impedance transformer (14), and a three-quarter-wavelength impedance matching line (15) are printed on the lower surface of the upper dielectric plate (1) and are connected in sequence, the impedance matching line (15) is bent into a ring shape from the outside to the inside, four antenna arms (16) that are perpendicular to each other and spaced by a quarter wavelength are provided on the impedance matching line (15), the impedance transformer (14), the impedance matching line (15), and the antenna arms (16) are located within the projection range of the slit (12), an impedance matching patch (17) that is disposed opposite to and has the same size as the impedance transformer (14) and an annular patch (18) that is disposed opposite to and has the same size as the impedance matching line (15) are provided in the slit (12); a second copper-clad layer (31) is printed on the lower surface of the lower dielectric plate (3), circular metal patches (32) arranged periodically are printed on the upper surface of the lower dielectric plate (3), a metal via hole (33) is provided on each circular metal patch (32), and each metal via hole (33) penetrates the lower dielectric plate (3) and is connected to the second copper-clad layer (31).

[0007] Preferably, the antenna arm (16) includes a short arm (161) connected to the impedance matching line (15) and a long arm (162) perpendicularly connected to the short arm (161).

[0008] Preferably, the lengths of the four antenna arms (16) increase in sequence.

[0009] Preferably, taking the length of one antenna arm (16) as the reference length, the lengths of the remaining three antenna arms (16) are respectively the reference length multiplied by a preset length factor, the reference length multiplied by the square of the preset length factor, and the reference length multiplied by the cube of the preset length factor.

[0010] Preferably, the circular metal patches (32) are arranged only outside the projection range of the slit (12) on the upper surface of the lower dielectric plate (3).

[0011] Preferably, both the upper dielectric plate (1) and the lower dielectric plate (3) are made of Rogers5880 plates, and the impedance matching patch (17) and the annular patch (18) are made of conductive materials.

[0012] Preferably, the thicknesses of the upper dielectric plate (1), the spacer dielectric plate (2), and the lower dielectric plate (3) are 0.508 mm, 0.254 mm, and 0.787 mm respectively, and the outer contour dimensions of the integrated substrate gap waveguide four-arm circularly polarized antenna are 30 mm × 16 mm × 1.549 mm.

[0013] Preferably, by changing the curvature radius of the impedance matching line, the center frequency of the antenna is shifted.

[0014] Preferably, by changing the length ratio of the short arm (161) to the long arm (162) of the antenna arm (16), the axial ratio of the antenna is adjusted; by changing the preset length factor, the axial ratio bandwidth performance of the antenna is adjusted.

[0015] Preferably, the upper dielectric plate (1), the spacer dielectric plate (2), and the lower dielectric plate (3) are bonded together or fixed together by screws.

[0016] Different from the prior art, the beneficial effects of the present invention are as follows: By adopting three dielectric plates, a copper-clad layer and slits are printed on the upper surface of the upper dielectric plate, a feeding microstrip line, an impedance transformer, and an impedance matching line are printed on the lower surface, the impedance matching line is bent into a ring from the outside to the inside, and four antenna arms perpendicular to each other and spaced by a quarter wavelength are provided. An impedance matching patch that is disposed opposite to and has the same size as the impedance transformer and a circular patch that is disposed opposite to and has the same size as the impedance matching line are provided in the slit. The four antenna arms generate circularly polarized waves, and the slit radiates circularly polarized waves to form an ISGW circularly polarized antenna, thereby being able to simplify the antenna structure, improve the antenna gain and bandwidth, and improve the axial ratio bandwidth performance, having the advantages of simple structure, wide bandwidth, strong anti-interference ability, easy processing and integration, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of the integrated substrate gap waveguide four-arm circularly polarized antenna according to an embodiment of the present invention.

[0018] Figure 2 is Figure 1 a bottom view schematic diagram of the upper dielectric plate of the integrated substrate gap waveguide four-arm circularly polarized antenna shown in

[0019] Figure 3 is Figure 1 a top view schematic diagram of the lower dielectric plate of the integrated substrate gap waveguide four-arm circularly polarized antenna shown in

[0020] Figure 4 is Figure 1 a bottom view schematic diagram of the lower dielectric plate of the integrated substrate gap waveguide four-arm circularly polarized antenna shown in

[0021] Figure 5 isFigure 1 S-parameter simulation result diagram of the integrated substrate gap waveguide four-arm circularly polarized antenna shown in the figure. Specific implementation manners

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0023] Refer to Figures 1 to 5 , the integrated substrate gap waveguide four-arm circularly polarized antenna in the embodiment of the present invention includes an upper dielectric plate 1, a lower dielectric plate 3, and a spacer dielectric plate 2 disposed between the upper dielectric plate 1 and the lower dielectric plate 3.

[0024] A first copper-clad layer 11 is printed on the upper surface of the upper dielectric plate 1, and a slot 12 is provided on the first copper-clad layer 11. A feeding microstrip line 13, a quarter-wavelength impedance transformer 14, and a three-quarter-wavelength impedance matching line 15 are sequentially connected and printed on the lower surface of the upper dielectric plate 1. The impedance matching line 15 is bent into a ring shape from the outside to the inside. Four antenna arms 16 that are perpendicular to each other and spaced by a quarter wavelength are provided on the impedance matching line 15. The impedance transformer 14, the impedance matching line 15, and the antenna arms 16 are located within the projection range of the slot 12. An impedance matching patch 17 that is disposed opposite to and has the same size as the impedance transformer 14 and a circular patch 18 that is disposed opposite to and has the same size as the impedance matching line 15 are provided in the slot 12. The bent portions of the impedance matching line 15 and the circular patch 18 can be approximately or equal to a circular ring. The shape of the slot 12 can be rectangular or other shapes.

[0025] A second copper-clad layer 31 is printed on the lower surface of the lower dielectric plate 3, and circular metal patches 32 arranged periodically are printed on the upper surface of the lower dielectric plate 3. A metal via 33 is provided on each circular metal patch 32, and each metal via 33 penetrates through the lower dielectric plate 3 and is connected to the second copper-clad layer 31. The metal via 33 can be in the shape of a circle, a square, etc. Each circular metal patch 32 and the metal via 33 thereon form a mushroom-shaped EBG structure. In this way, a periodically arranged mushroom-shaped EBG structure is formed on the lower dielectric plate 3.

[0026] The spacer dielectric plate 2 is used to separate the upper dielectric plate 1 and the lower dielectric plate 3, so as to form a gap between the upper dielectric plate 1 and the lower dielectric plate 3. The upper dielectric plate 1, the lower dielectric plate 3, and the spacer dielectric plate 2 can be bonded together or fixed together by screws.

[0027] The first copper-clad layer 11 on the upper dielectric substrate 1 is equivalent to an ideal electric conductor (PEC), and the lower dielectric substrate 3 is equivalent to an ideal magnetic conductor (PMC). The upper dielectric substrate 1, the spacer dielectric substrate 2, the lower dielectric substrate 3, the first copper-clad layer 11, the feeding microstrip line 13, the periodically arranged mushroom-shaped EBG structure, and the second copper-clad layer 31 together constitute an integrated substrate gap waveguide (ISGW) structure. One end of the feeding microstrip line 13 located at the edge of the ISGW structure is set as the feeding port A. The other end of the feeding microstrip line 13 feeds four antenna arms 16 through an impedance transformer 14 and an impedance matching line 15 to generate a circularly polarized wave, and the generated circularly polarized wave radiates out from the slot 12. And the annular patch 18 in the slot 12 can cancel the electromagnetic field generated by the feeding microstrip line 13 in the far field, thereby improving the axial ratio bandwidth and gain of the antenna. In addition, the current of the annular patch 18 and the current of the impedance matching line 15 are equal in magnitude and opposite in direction, which can cancel the electromagnetic field generated by the impedance matching line 15 in the far field, and further improve the axial ratio bandwidth and gain of the antenna.

[0028] In this embodiment, the antenna arm 16 includes a short arm 161 connected to the impedance matching line 15 and a long arm 162 vertically connected to the short arm 161. The lengths of the four antenna arms 16 increase in sequence. For example, taking the length of one antenna arm 16 as the reference length, the lengths of the remaining three antenna arms 16 are respectively the reference length multiplied by a preset length factor, the reference length multiplied by the square of the preset length factor, and the reference length multiplied by the cube of the preset length factor. Among them, the radius of curvature of the impedance matching line 15 affects the amplitude of the orthogonal electric field. By changing the radius of curvature of the impedance matching line 15, the center frequency of the antenna can be shifted. For example, both the impedance bandwidth and the axial ratio bandwidth can be narrowed. After verification by the inventors of the present application, when the impedance matching line 15 is circular and the radius is equal to 0.875 mm, the return loss of the antenna reaches the best. By changing the preset length factor, the current distribution and the axial ratio bandwidth on the four antenna arms 16 can be changed to adjust the axial ratio bandwidth performance of the antenna. For example, the impedance bandwidth can remain unchanged and the axial ratio bandwidth can be narrowed. After verification by the inventors of the present application, when the preset length factor is 0.96, the axial ratio bandwidth is the best. By changing the length ratio of the short arm 161 to the long arm 162 of the antenna arm 16, the axial ratio of the antenna can be adjusted. After verification by the inventors of the present application, when the length ratio of the short arm 161 to the long arm 162 is 0.65, the axial ratio of the antenna is the best and the circular polarization performance is the best.

[0029] In this embodiment, the circular metal patches 32 are only arranged outside the projection range of the slot 12 on the upper surface of the lower dielectric substrate 3. That is to say, the area on the upper surface of the lower dielectric substrate 3 directly opposite to the slot 12 is a blank area, and no circular metal patches 32 are provided.

[0030] To illustrate the integrated substrate gap waveguide four-arm circularly polarized antenna of this embodiment in detail, a specific example is given below. In this specific example, both the upper dielectric plate 1 and the lower dielectric plate 3 are made of Rogers5880 material. The thicknesses of the upper dielectric plate 1, the spacer dielectric plate 2, and the lower dielectric plate 3 are 0.508 mm, 0.254 mm, and 0.787 mm respectively. The outer contour dimensions of the integrated substrate gap waveguide four-arm circularly polarized antenna are 30 mm × 16 mm × 1.549 mm. The impedance matching patch 17 and the annular patch 18 are made of a conductive material, such as copper. Through simulation and testing, from Figure 5 the simulation results of the S11 parameter, it can be seen that the -10 dB impedance bandwidth of this antenna ranges from 30.5 - 37.9 GHz (about 21.8%); the axial ratio bandwidth (AR below 3 dB) frequency range of the antenna is 32.7 - 35.5 GHz (about 8.2%); the gain of the antenna is 6.6 dBi at 34 GHz. The test shows that the integrated substrate gap waveguide four-arm circularly polarized antenna of this embodiment is superior to the traditional circularly polarized antenna in terms of bandwidth and gain. Among them, S11 represents the return loss.

[0031] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. An integrated substrate gap waveguide four-arm circularly polarized antenna, characterized in that, It includes an upper dielectric plate (1), a lower dielectric plate (3), and a spacer dielectric plate (2) disposed between the upper dielectric plate (1) and the lower dielectric plate (3); A first copper-clad layer (11) is printed on the upper surface of the upper dielectric plate (1). A slit (12) is provided on the first copper-clad layer (11). A feeding microstrip line (13), a quarter-wavelength impedance transformer (14), and a three-quarter-wavelength impedance matching line (15) are printed in sequence on the lower surface of the upper dielectric plate (1). The impedance matching line (15) is bent into a ring shape from the outside to the inside. Four antenna arms (16) that are perpendicular to each other and spaced by a quarter wavelength are provided on the impedance matching line (15). The impedance transformer (14), the impedance matching line (15), and the antenna arms (16) are within the projection range of the slit (12). An impedance matching patch (17) that is disposed opposite to and has the same size as the impedance transformer (14) and an annular patch (18) that is disposed opposite to and has the same size as the impedance matching line (15) are provided in the slit (12); A second copper-clad layer (31) is printed on the lower surface of the lower dielectric plate (3). Circular metal patches (32) arranged periodically are printed on the upper surface of the lower dielectric plate (3). A metal via hole (33) is provided on each circular metal patch (32). Each metal via hole (33) penetrates the lower dielectric plate (3) and is connected to the second copper-clad layer (31); The antenna arm (16) includes a short arm (161) connected to the impedance matching line (15) and a long arm (162) perpendicularly connected to the short arm (161); the lengths of the four antenna arms (16) increase in sequence; taking the length of one antenna arm (16) as the reference length, the lengths of the other three antenna arms (16) are respectively the reference length multiplied by a preset length factor, the reference length multiplied by the square of the preset length factor, and the reference length multiplied by the cube of the preset length factor.

2. The integrated substrate gap waveguide four-arm circularly polarized antenna according to claim 1, characterized in that, The circular metal patches (32) are arranged only outside the projection range of the slit (12) on the upper surface of the lower dielectric plate (3).

3. The integrated substrate gap waveguide four-arm circularly polarized antenna according to claim 1, characterized in that, Both the upper dielectric plate (1) and the lower dielectric plate (3) are made of Rogers5880 plates, and the impedance matching patch (17) and the annular patch (18) are made of conductive materials.

4. The integrated substrate gap waveguide four-arm circularly polarized antenna according to claim 3, characterized in that, The thicknesses of the upper dielectric plate (1), the spacer dielectric plate (2), and the lower dielectric plate (3) are 0.508 mm, 0.254 mm, and 0.787 mm respectively, and the outer contour dimensions of the integrated substrate gap waveguide four-arm circularly polarized antenna are 30 mm × 16 mm × 1.549 mm.

5. The integrated substrate gap waveguide four-arm circularly polarized antenna according to claim 1, characterized in that, By changing the curvature radius of the impedance matching line, the center frequency of the antenna is offset.

6. The integrated substrate gap waveguide four-arm circularly polarized antenna according to claim 1, characterized in that, By changing the length ratio of the short arm (161) to the long arm (162) of the antenna arm (16), the axial ratio of the antenna is adjusted; by changing the preset length factor, the axial ratio bandwidth performance of the antenna is adjusted.

7. The integrated substrate gap waveguide four-arm circularly polarized antenna according to claim 1, characterized in that, The upper dielectric plate (1), the spacer dielectric plate (2), and the lower dielectric plate (3) are bonded together or fixed together by screws.

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