Broadband compact low-sidelobe planar array antenna

Abstract

The utility model relates to a broadband compact low-sidelobe planar array antenna, which comprises a dielectric substrate layer, a radiation patch and a feed network which are arranged on the upper surface of the dielectric substrate layer, a metal floor layer which is arranged on the lower surface of the dielectric substrate layer, and a coaxial port which is arranged at the central position of the feed network. The radiation patch is connected with the feed network, a central signal hole and peripheral grounding holes of the coaxial port penetrate through the dielectric substrate layer, one end of the central signal hole is connected with the feed network, the other end of the central signal hole is separated from the metal floor layer, and the lower layer of the peripheral grounding holes is connected with the metal floor layer; the metal floor layer is provided with rectangular windows which are arranged in an array mode to form a surrounding ground structure so as to improve impedance bandwidth. According to the utility model, the metal floor layer is provided with the rectangular window, and the umbrella-shaped radiation patch is used for widening the impedance bandwidth, so that the wider impedance bandwidth is realized.

Description

TECHNICAL FIELD

[0001] The utility model relates to antenna technical field especially relates to a wideband compact low side lobe planar array antenna. BACKGROUND

[0002] Planar patch antennas are an important branch of microwave antennas, widely used in mobile communication due to their small size, light weight, and ultra-low profile. However, planar patch antennas typically have a narrow operating frequency band, which limits their application range. The side lobe level of an antenna is an important performance indicator, crucial for enhancing the antenna's anti-interference capability. Higher side lobe levels can easily lead to greater clutter interference. Generally, for array antennas with equal amplitude and in-phase feeding, the side lobe level is typically around -13 dB. Low side lobe antennas have the advantages of narrow beam, high gain, and low side lobe, and can significantly suppress electromagnetic interference in directions outside the main lobe. Therefore, researching array antennas with low side lobe characteristics has important engineering value. At the same time, the compactness of planar array antennas is also crucial, as it enables the antenna to be deployed in limited space while maintaining high performance. By integrating more radiation units, planar array antennas can achieve higher directivity and beam control capabilities, meeting the high requirements for signal quality and coverage in modern communication, radar, and Internet of Things fields. In addition, compact design also reduces manufacturing and maintenance costs, improves system reliability, making it a preferred choice in various technical applications.

[0003] A wideband miniaturized microstrip array antenna is disclosed in Chinese patent application No. 202420430381.6. The array antenna is composed of a ground plate, upper and lower layer dielectric substrates. Each unit's metal patch is provided with two opposite U-shaped grooves and a groove, and a double-layer structure and a small amount of metallized feed-through are used to realize the connection of the feed network. At the same time, the setting of U-shaped grooves and grooves effectively widens the frequency band of the antenna and improves the bandwidth performance. However, multiple layers of dielectric substrates are required, increasing the cost. And the unit spacing is greater than 0.7 times the wavelength, which is not compact. A new type of low side lobe microstrip array antenna is disclosed in Chinese patent application No. 201921746983.8. The microstrip array antenna includes a dielectric substrate, a 1x16 slot-loaded microstrip antenna array, and a one-to-sixteen microstrip coupling unequal power division network. The metal ground plate is located on the lower surface, and the standard port is located on one side. The antenna array is directly fed through the power division network, combined with a new type of miniaturized feed network, to achieve high gain, low side lobe performance, and wide operating bandwidth. However, no face array design is performed. And the side lobe level suppression level is less than 20 dB.

[0004] Therefore, the current planar array antenna has technical problems in wideband, compact size and low sidelobe. Specifically, the existing antenna often has bandwidth limitation, which cannot meet the demand of wideband communication. Meanwhile, the unit spacing of part of the array design is large, which leads to large overall volume of the array, and is not suitable for the compact design of modern electronic equipment. In addition, high sidelobe level can cause signal interference and insufficient directivity. Utility model content

[0005] The utility model discloses a wideband compact low sidelobe planar array antenna, which solves the problems of the prior art.

[0006] The utility model discloses a wideband compact low sidelobe planar array antenna, which solves the problems of the prior art.

[0007] The radiation patch is connected with the feed network, the central signal hole of the coaxial port and the peripheral ground hole penetrate the dielectric substrate layer, one end of the central signal hole is connected with the feed network, the other end is separated from the metal floor layer, and the lower layer of the peripheral ground hole is connected with the metal floor layer.

[0008] The radiation patch includes a rectangular patch that is smoothly processed to form an umbrella structure, so as to widen the impedance bandwidth.

[0009] The feed network adopts a series-parallel hybrid connection structure, and a quarter of a dielectric wavelength impedance transformation section and a bent second microstrip line are connected in series between two radiation patches.

[0010] The feed network is composed of 8 horizontal feed lines and 1 vertical feed line.

[0011] One side of the horizontal feed line located on the left side or the right side of the vertical feed line includes a first impedance transformation section, a second impedance transformation section, a third impedance transformation section and a fourth impedance transformation section.

[0012] The lower half or the upper half of the vertical feed line which is symmetrical to the coaxial port includes a fifth impedance transformation section, a sixth impedance transformation section, a seventh impedance transformation section and an eighth impedance transformation section; the third microstrip line is connected between every two adjacent impedance transformation sections through bending.

[0013] The third microstrip line has the same configuration as the second microstrip line, the fifth impedance transformation section has the same configuration as the first impedance transformation section, the sixth impedance transformation section has the same configuration as the second impedance transformation section, the seventh impedance transformation section has the same configuration as the third impedance transformation section, and the eighth impedance transformation section has the same configuration as the fourth impedance transformation section.

[0014] The utility model has the advantages of the following:

[0015] 1. The rectangular window and the umbrella-shaped radiation patch are adopted to widen the impedance bandwidth, and a wide impedance bandwidth is realized.

[0016] 2. The antenna array designs the radiation patch and the feed network on the same layer. The design is completed under the condition of only using one medium substrate, and the cost is greatly saved.

[0017] 3. The bending microstrip line is used between the units in the antenna array. Generally, the unit spacing of the conventional planar microstrip antenna array design is greater than 0.5 times the central wavelength, but the unit spacing is reduced to 0.5 times the central wavelength by adopting the bending microstrip line, and the compact array design is realized.

[0018] 4. The Taylor synthesis method is adopted to control the current amplitude distribution between the units, and the function of suppressing the sidelobe level is realized. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the utility model;

[0020] Figure 2 It is a structural schematic diagram of the antenna unit;

[0021] Figure 3 It is a schematic diagram of the feed network;

[0022] Figure 4 It is a structural schematic diagram of the metal floor layer;

[0023] Figure 5 It is a structural schematic diagram of the transverse feed line;

[0024] Figure 6 It is a structural schematic diagram of the longitudinal feed line;

[0025] Figure 7 It is a structural schematic diagram of the antenna unit; S 11a plot as a function of frequency;

[0026] Figure 8 antenna array S 11 a plot as a function of frequency;

[0027] Figure 9 antenna array at 2.4 GHz;

[0028] In the figure: 1 - dielectric substrate layer, 2 - radiation patch, 3 - feed network, 4 - metal ground plane layer, 5 - coaxial port, 6 - first microstrip line, 7 - rectangular window, 8 - transverse feed line, 9 - longitudinal feed line, 10 - first impedance transformation section, 11 - second impedance transformation section, 12 - third impedance transformation section, 13 - fourth impedance transformation section, 14 - second microstrip line, 15 - fifth impedance transformation section, 16 - sixth impedance transformation section, 17 - seventh impedance transformation section, 18 - eighth impedance transformation section, 19 - third microstrip line. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in combination with the drawings of the present application is not intended to limit the protection scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present application. The present application will be further described below in combination with the drawings.

[0030] As Figure 1 shown, the utility model of a kind of broadband compact low sidelobe planar array antenna, including dielectric substrate layer 1, radiation patch 2 and feed network 3 being located dielectric substrate layer 1 upper surface, metal ground plane layer 4 being located dielectric substrate layer 1 lower surface, coaxial port 5 being located feed network 3 center position.

[0031] Wherein, dielectric substrate layer 1 uses FR-4 plate material, relative dielectric constant is 4.6, loss tangent is 0.018, thickness is 1.6 mm.The size of entire antenna array is 500 mm x 500 mm x 1.6 mm.

[0032] As Figure 2The antenna array is composed of antenna elements. For the design of the antenna element, first, a conventional rectangular patch antenna element is designed, but its impedance bandwidth is very narrow. In order to widen the impedance bandwidth, a rectangular window 7 is opened in the metal ground layer 4, forming a "surrounding ground" structure, and the impedance bandwidth is significantly improved. In order to further widen the impedance bandwidth, the rectangular patch is rounded. Finally, the rectangular patch evolves into a radiation patch 2, which is approximately umbrella-shaped. Here, the antenna element uses a first microstrip line 6 with a characteristic impedance of 100 Ω for impedance matching. This design not only helps to reduce the overall size of the array antenna, but also the relatively narrow 100 Ω microstrip feed line can reduce the spurious radiation and coupling loss caused by the feed network. The overall size of the antenna element is 62.5 mm x 62.5 mm x 1.6 mm, the size of the rectangular window 7 is 44.7 mm x 28.5 mm, the length and width of the rectangular part in the radiation patch 2 are 27.6 mm x 8.4 mm, the length and short axis ratio of the elliptical part is 0.67, and the width of the first microstrip line 6 is 0.61 mm.

[0033] The feed network of the antenna array is the key to realizing compact size and sidelobe suppression. To simplify the current ratio control between array elements and reduce the complexity of the feed network, the feed network 3 adopts a series-parallel hybrid design. A quarter-wave impedance transformation section is connected in series between two antenna elements to adjust the characteristic impedance ratio of the section to the main feed line, thereby achieving non-uniform distribution of element currents. At the same time, the length of the microstrip transmission line between adjacent elements should be one wavelength, but if the spacing is one wavelength, it will exceed 0.5 times the center wavelength. To reduce the element spacing, the microstrip transmission line in the design is bent except for the quarter-wave impedance transformation section, ensuring that the length of the microstrip transmission line is one wavelength when the spacing is 0.5 times the center wavelength. As shown in Figure 3 The upper metal layer of the antenna array contains 8 x 8 arranged radiation patches 2 and a feed network 3. The feed network 3 is composed of 8 horizontal feed lines 8 and 1 vertical feed line 9. Each horizontal feed line 8 connects 8 radiation patches 2 in each row, thereby forming a linear array. The 1 vertical feed line 9 connects 8 horizontal feed lines 8, thereby forming a planar array and completing the connection of 64 elements. Each horizontal feed line 8 is symmetric about the vertical feed line 9 connection point, and the vertical feed line 9 is symmetric about the coaxial port 5 up and down. As shown in Figure 4 The coaxial port 5 passes through the center of the vertical feed line 9, the dielectric substrate layer 1 and the metal ground layer 4 from top to bottom.

[0034] As shown in Figure 5The characteristic impedance of the rest of the microstrip line is 100 Ω except for the first impedance transformation section 10, the second impedance transformation section 11, the third impedance transformation section 12 and the fourth impedance transformation section 13. The second microstrip line 14 with a bend is used to connect adjacent impedance transformation sections. For the right half of the transverse feed line, from right to left, there are the first impedance transformation section 10, the second microstrip line 14, the second impedance transformation section 11, the second microstrip line 14, the third impedance transformation section 12, the second microstrip line 14 and the fourth impedance transformation section 13.

[0035] The designed antenna array is expected to control the sidelobe level to be lower than -20 dB. However, in the actual antenna array, the sidelobe level may be raised due to the mutual coupling between the antenna elements. Therefore, the designed sidelobe level is usually set lower than the target value. To ensure that the sidelobe level is less than -20 dB, the Taylor synthesis method with a -25 dB sidelobe level suppression is used in this design.

[0036] Specifically, Table 1 is the current distribution of the 8-element linear array calculated according to the Taylor synthesis method, i.e., the current amplitude distribution of each element of the 8-element linear array is 0.40, 0.59, 0.85, 1.00, 1.00, 0.85, 0.59 and 0.40, respectively.

[0037] Table 1, current amplitude distribution table of 8-element linear array

[0038]

[0039] According to the current distribution of the 8-element linear array, the characteristic impedances of the second impedance transformation section 11, the third impedance transformation section 12 and the fourth impedance transformation section 13 are calculated to be 84.61 Ω, 69.93 Ω and 68.82 Ω, respectively. Thus, the characteristic impedance of the first impedance transformation section 10 is calculated to be 66.94 Ω. According to the characteristic impedances of the first impedance transformation section 10, the second impedance transformation section 11, the third impedance transformation section 12 and the fourth impedance transformation section 13, the corresponding widths are calculated to be 1.64 mm, 0.96 mm, 1.50 mm and 1.55 mm, respectively, and the lengths are all 16 mm.

[0040] After the design of the single-row 8-element linear array is completed, the single-row linear array is taken as an independent element to form an 8x8 rectangular antenna array. As shown in FIG. 4, the 8x8 rectangular antenna array is composed of 64 single-row 8-element linear arrays. Figure 6As shown, it is the upper half of the vertical feed line 9, in addition to the fifth impedance transformation section 15, the sixth impedance transformation section 16, the seventh impedance transformation section 17 and the eighth impedance transformation section 18, the characteristic impedance of the rest of the microstrip line is 100 Ω. The third microstrip line 19 with a bending microstrip line is connected between adjacent impedance transformation sections. For the upper half of the vertical feed line, from bottom to top, it is the fifth impedance transformation section 15, the third microstrip line 19, the sixth impedance transformation section 16, the third microstrip line 19, the seventh impedance transformation section 17, the third microstrip line 19 and the eighth impedance transformation section 18. The third microstrip line 19 has the same configuration as the second microstrip line 14. The fifth impedance transformation section 15 has the same configuration as the first impedance transformation section 10, the sixth impedance transformation section 16 has the same configuration as the second impedance transformation section 11, the seventh impedance transformation section 17 has the same configuration as the third impedance transformation section 12, and the eighth impedance transformation section 18 has the same configuration as the fourth impedance transformation section 13.

[0041] At this time, the current amplitude distribution of the 8 × 8 planar array is equal to the transpose of the linear array current amplitude distribution multiplied by the linear array current amplitude distribution. Table 2 is the current amplitude distribution corresponding to each unit of the 8 × 8 planar array.

[0042] Table 2, current amplitude distribution table of 8 × 8 planar array

[0043]

[0044] As Figure 7 shown, the S 11 curve with frequency variation. The impedance bandwidth of the antenna unit at -10 dB is 44.8% (1.89-2.98 GHz), which realizes a wide impedance bandwidth.

[0045] As Figure 8 shown, the S 11 curve with frequency variation. The impedance bandwidth of the antenna array at -10 dB is greater than 61.8% (1.69-3.2 GHz), which realizes a wide impedance bandwidth.

[0046] As Figure 9 shown, the

[0047] The utility model discloses a low side lobe characteristic antenna array, comprising a metal floor layer 4, a plurality of units, a vertical feed line 9 and a coaxial port 5, wherein the unit comprises a radiation patch 2 and a feed network 3, the radiation patch 2 is arranged on the metal floor layer 4, the feed network 3 is arranged on the metal floor layer 4 and is connected with the radiation patch 2, the vertical feed line 9 is arranged on the metal floor layer 4 and is connected with the feed network 3, and the coaxial port 5 is arranged on the metal floor layer 4 and is connected with the vertical feed line 9.

[0048] When the antenna array is transmitting, radio frequency signals enter through the coaxial port 5, are transmitted to the center point of each horizontal feed line 8 through the vertical feed line 9, are transmitted to the radiation patch 2 of each unit through each horizontal feed line 8, and are radiated outward to form a beam.

[0049] When the antenna array is receiving, the radiation patch 2 of each unit receives radio frequency signals, transmits the radio frequency signals to the vertical feed line 9 through the horizontal feed line 8, and then transmits the radio frequency signals to the coaxial port 5 through the vertical feed line 9, so that the radio frequency signals enter the system connected behind.

[0050] By using a power divider that divides one into sixty-four unequal powers, the current obtained by each patch in the array conforms to Taylor distribution, so that the low side lobe characteristic of the antenna array is realized.

[0051] The above is only the preferred embodiment of the utility model, and it should be understood that the utility model is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used for various other combinations, modifications and improvements, and can be changed within the scope of the concept described herein through the above teaching or related technical or knowledge. The changes and variations made by the person skilled in the art do not deviate from the spirit and scope of the utility model, and should be within the protection scope of the claims attached to the utility model.

Claims

1. A wideband compact low sidelobe planar array antenna, characterized by: It includes a medium substrate layer (1), a radiation patch (2) and a feed network (3) are arranged on the upper surface of the medium substrate layer (1), a metal ground plane layer (4) is arranged on the lower surface of the medium substrate layer (1), and a coaxial port (5) is arranged at the center position of the feed network (3); The radiation patch (2) is connected with the feed network (3), the center signal hole of the coaxial port (5) and the surrounding ground hole penetrate the medium substrate layer (1), one end of the center signal hole is connected with the feed network (3), the other end is separated from the metal ground plane layer (4), and the lower layer of the surrounding ground hole is connected with the metal ground plane layer (4); The metal ground plane layer (4) is provided with a plurality of rectangular windows (7) arranged in an array, forming a surrounding ground structure to improve the impedance bandwidth.

2. A wideband compact low sidelobe planar array antenna according to claim 1, characterized in that: The radiation patch (2) includes a rectangular patch which is smoothly processed to form an umbrella-shaped structure to broaden the impedance bandwidth, and the number of radiation patches (2) is consistent with the number of rectangular windows (7), and each radiation patch (2) is located directly above the corresponding rectangular window (7).

3. The wideband compact low sidelobe planar array antenna according to claim 1, characterized in that: The feed network (3) adopts a series-parallel hybrid connection structure, and a quarter of a dielectric wavelength impedance transformation section and a bent second microstrip line (14) are connected in series between two radiation patches (2), and the length of the bent microstrip transmission line is three quarters of a dielectric wavelength.

4. A wideband compact low sidelobe planar array antenna according to claim 3, characterized in that: The feed network (3) is composed of 8 horizontal feed lines (8) and 1 vertical feed line (9), each horizontal feed line (8) connects 8 radiation patches (2) in each row to form a linear array, and the 1 vertical feed line (9) connects the 8 horizontal feed lines (8) to form a planar array; each horizontal feed line (8) is symmetric about the vertical feed line (9) connection point left and right, and the vertical feed line (9) is symmetric about the coaxial port (5) up and down.

5. A wideband compact low sidelobe planar array antenna according to claim 4, characterized in that: The side of the horizontal feed line (8) located on the left side or the right side of the vertical feed line (9) includes a first impedance transformation section (10), a second impedance transformation section (11), a third impedance transformation section (12) and a fourth impedance transformation section (13); each two adjacent impedance transformation sections are connected by a second microstrip line (14) with a bend, and the radiation patch (2) is connected with the corresponding impedance transformation section by a first microstrip line (6).

6. A wideband compact low sidelobe planar array antenna according to claim 5, characterized in that: The lower half or the upper half of the vertical feed line (9) which is symmetrical about the coaxial port (5) includes a fifth impedance transformation section (15), a sixth impedance transformation section (16), a seventh impedance transformation section (17) and an eighth impedance transformation section (18); each two adjacent impedance transformation sections are connected by a third microstrip line (19) with a bend.

7. A wideband compact low sidelobe planar array antenna according to claim 6, characterized in that: The third microstrip line (19) has the same configuration as the second microstrip line (14), the fifth impedance transformation section (15) has the same configuration as the first impedance transformation section (10), the sixth impedance transformation section (16) has the same configuration as the second impedance transformation section (11), the seventh impedance transformation section (17) has the same configuration as the third impedance transformation section (12), and the eighth impedance transformation section (18) has the same configuration as the fourth impedance transformation section (13).

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