A broadband, low-profile, low-cross-polarization dielectric patch antenna

Abstract

The present invention discloses a broadband, low-profile, low-cross-polarization dielectric patch antenna, comprising a dielectric body, and metal patches, slotted metal sheets, coupled microstrip lines, and a metal floor, which are arranged on and supported by the dielectric body, are parallel to each other, are separated from each other, and are stacked in layers in sequence. A slot is provided on the slotted metal sheet; and the coupled microstrip line is located below the slot. The metal patch is a square sheet. Four metal posts are connected to the four corners of the square sheet metal patch. The metal posts are arranged in the dielectric body, between the metal patch and the slotted metal sheet, and are connected to the metal patch at their top ends. The coupled microstrip line connects the feed microstrip line. The slots include U-shaped slots and H-shaped slots surrounded by the U-shaped slots. The coupled microstrip line is called a T-shaped slot. Compared to ordinary patch antennas, the antenna of the present invention has a smaller size and profile, and has a wider bandwidth and good radiation characteristics.

Description

Technical Field

[0001] The present invention relates to a dielectric patch antenna, in particular to a dielectric patch antenna with low cross-polarization slot coupling. Background Art

[0002] Antennas are essential components in electronic engineering and wireless communications, used to transmit and receive electromagnetic waves. With the rapid development of wireless communication technology, the performance requirements for antennas are becoming increasingly stringent. Broadband, low profile, and low cross-polarization are currently key trends in antenna design. In the microwave frequency band, particularly in the 11 GHz to 13 GHz frequency range, antenna design must meet specific performance requirements, such as impedance bandwidth, cross-polarization, and beamwidth.

[0003] A dielectric patch antenna uses a dielectric as its resonator and waveguide core. This antenna enhances coupling efficiency and improves energy transmission efficiency through electromagnetic coupling between the dielectric and the feed structure. The dielectric's low loss and high dielectric constant confine electromagnetic waves to a specific path, optimizing radiation direction. Furthermore, the antenna's dielectric shape and feed position can manipulate the antenna's electromagnetic wave resonant modes, such as TE and TM, to achieve high radiation efficiency. Summary of the Invention

[0004] The problem to be solved by the present invention is to achieve the performance requirements of the antenna such as impedance bandwidth, cross polarization and beam bandwidth within the frequency range of 11 GHz to 13 GHz.

[0005] To solve the above problems, the present invention adopts the following solutions:

[0006] According to the present invention, a broadband, low-profile, low-cross-polarization dielectric patch antenna includes a dielectric body, and metal patches, slotted metal sheets, coupled microstrip lines, and a metal floor, which are arranged on and supported by the dielectric body, are parallel to each other, are separated from each other, and are stacked in layers in sequence. The slotted metal sheet is provided with a slot; the coupled microstrip line is located below the slot; the metal patch is a square sheet; four metal pillars are vertically connected to the four corners of the square metal patch; the metal pillars are arranged in the dielectric body, between the metal patch and the slotted metal sheet, and have their top ends connected to the metal patch; and the coupled microstrip line is connected to the feed microstrip line.

[0007] Furthermore, the metal column is connected to the metal patch by welding.

[0008] Furthermore, the slot metal sheet is a square sheet; the size of the slot metal sheet is larger than the metal patch, and the center of the slot metal sheet is aligned with the center of the metal patch.

[0009] Furthermore, the dielectric body includes a first dielectric layer, a second dielectric layer and a third dielectric layer; the metal patch is arranged on the top surface of the first dielectric layer; the slotted metal sheet is arranged on the top surface of the second dielectric layer; the feeding microstrip line and the coupling microstrip line are arranged on the top surface of the third dielectric layer; the bottom surface of the third dielectric layer is connected to the metal floor; the bottom surface of the second dielectric layer covers the coupling microstrip line and the feeding microstrip line arranged on the third dielectric layer and is bonded to the third dielectric layer; the bottom surface of the first dielectric layer covers the slotted metal sheet arranged on the second dielectric layer and is bonded to the second dielectric layer.

[0010] Furthermore, the dielectric constant of the first dielectric layer is 1.06, and the loss tangent is 0.0001; the dielectric constant of the second dielectric layer is 2.20, and the loss tangent is 0.0009; and the dielectric constant of the third dielectric layer is 2.20, and the loss tangent is 0.0009.

[0011] Furthermore, the thickness of the second dielectric layer and the third dielectric layer is 0.02A, where A is the center wavelength of the antenna operating frequency.

[0012] Furthermore, the gap includes a U-shaped gap; the U-shaped gap includes a bottom seam and two first side seams that are parallel to each other, equal in length and flush at both ends; the bottom seam vertically connects one end of the two first side seams, so that the bottom seam and the two first side seams are connected to form a U-shaped structure.

[0013] Furthermore, the gap also includes an H-shaped gap; the H-shaped gap is located on the inner side of the U-shaped gap, including a center seam and two second side seams that are parallel to each other, equal in length, and flush at both ends; the two second side seams are located between the two first side seams, and are parallel to the first side seams, and are each equidistant from the adjacent first side seams; the center seam vertically connects the two second side seams, so that the center seam and the two second side seams form an H-shaped structure.

[0014] Furthermore, the coupled microstrip line includes a first microstrip line and a second microstrip line; wherein, the length direction of the first microstrip line is parallel to the first side seam, and is located on the central axis between the two first side seams; the length direction of the second microstrip line is perpendicular to the first side seam, and is located on the central axis between the two first side seams, and its front projection on the gap metal sheet is located on the inner side of the U-shaped gap; one end of the first microstrip line is connected to the feed microstrip line, and the other end is connected to the second microstrip line, and forms a T-shaped structure with the second microstrip line.

[0015] Furthermore, a front projection of the second microstrip line on the slotted metal sheet does not exceed a rectangular area enclosed by the bottom slot, the middle slot, and the two first side slots.

[0016] The technical effects of the present invention are as follows:

[0017] 1. The four metal pillars connected at the four corners of the bottom of the metal patch of the present invention can effectively expand the low-frequency impedance bandwidth and also play a role in fixing the metal patch;

[0018] 2. The antenna of the present invention operates in a frequency range of 11GHz to 13GHz. This covers multiple frequency bands and meets the broadband requirements of modern wireless communications. Compared to traditional patch antennas, the bandwidth of the present invention is wider and can adapt to more application scenarios.

[0019] 3. The antenna of the present invention has a small size and cross-section, which is conducive to device integration and meets the development requirements of small and portable devices;

[0020] 4. The antenna of the present invention guides the current flow path through the dual slot structure of U-shaped slots and H-shaped slots, introducing more resonant modes, so that the cross-polarization of these resonant modes cancels each other, thereby reducing the overall cross-polarization level to less than -30dB, thereby improving the communication efficiency of the device;

[0021] 5. By adding a smaller U-shaped gap inside the U-shaped gap, a relative bandwidth of about 16% can be achieved under the requirement that the impedance bandwidth is less than -10dB. However, under the requirement that the impedance bandwidth is less than -15dB, the relative bandwidth deteriorates. The present invention can optimize the inverted TM by adding an H-shaped gap inside the U-shaped gap. 20 Resonant mode, thereby achieving wider bandwidth under higher impedance bandwidth requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall three-dimensional structure of an embodiment of the dielectric patch antenna of the present invention.

[0023] Figure 2 It is a structural schematic diagram and dimension marking diagram of a cross-sectional view of an embodiment of a dielectric patch antenna of the present invention.

[0024] Figure 3 It is a structural schematic diagram and dimension marking diagram of a top view projection diagram of a dielectric patch antenna embodiment of the present invention.

[0025] Figure 4 4 is a reflection coefficient curve diagram of the dielectric patch antenna embodiment of the present invention.

[0026] Figure 5 4 is a cross-polarization curve diagram of the dielectric patch antenna embodiment of the present invention.

[0027] Figure 6 1 is an antenna gain curve diagram of an embodiment of the dielectric patch antenna of the present invention.

[0028] Figure 7 and Figure 8 They are antenna gain curves of the E plane and H plane of the dielectric patch antenna embodiment of the present invention.

[0029] Figure 1 、 Figure 2 、 Figure 3 middle,

[0030] 1 is a metal patch, 2 is a slotted metal patch, 3 is a coupled microstrip line, 31 is a first microstrip line, 32 is a second microstrip line, 4 is a metal floor, 5 is a slot, 51 is a U-shaped slot, 511 is a bottom slot, 512 is a first side slot, 52 is an H-shaped slot, 521 is a middle slot, 522 is a second side slot, 6 is a metal column, 9 is a dielectric body, 91 is a first dielectric layer, 92 is a second dielectric layer, and 93 is a third dielectric layer. For the convenience of example, Figure 1 In FIG, the first dielectric layer 91 and the second dielectric layer 92 are transparentized and are indicated by dotted lines. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Figure 1 A broadband, low-profile, low-cross-polarization dielectric patch antenna is illustrated. The antenna comprises a dielectric body 9, and a metal patch 1, a slotted metal sheet 2, a coupling microstrip line 3, and a metal ground plane 4, which are arranged on and supported by the dielectric body 9, parallel to each other, separated from each other, and stacked in a sequential order. The slotted metal sheet 2 has a slot 5. The coupling microstrip line 3 faces the slot 5 and connects to a feed microstrip line 39, which in turn connects to an RF connector via the feed microstrip line 39.

[0033] The metal floor 4 is a sheet-like body used for grounding. For ease of explanation, in this specification, the metal floor 4 is used as a reference ground, and the plane of the metal floor 4 is used as a horizontal plane. The farther away from the metal floor 4 is the upper side, and the closer to the metal floor 4 is the lower side. Based on the above reference, the dielectric patch antenna of the present invention is divided into four layers from top to bottom: the first layer, the metal patch layer, is provided with a metal patch 1; the second layer, the coupling slot layer, is provided with a slot metal sheet 2; the third layer, the coupling microstrip layer, is provided with a coupling microstrip line 3; the fourth layer, the metal floor layer, is provided with a metal floor 4. The metal patch 1, the slot metal sheet 2 and the coupling microstrip line 3 are all metal sheets, refer to Figure 2 and Figure 3 , and their thicknesses are marked as H1, H2, and H3 respectively.

[0034] To assemble the above-mentioned four-layer structure, the dielectric body is naturally divided into three layers: a first dielectric layer 91 on which the metal patch 1 is provided, a second dielectric layer 92 on which the slotted metal patch 2 is provided, and a third dielectric layer 93 on which the coupling microstrip line 3 and the metal floor 4 are provided. Specifically, the metal patch 1 is provided on the top surface of the first dielectric layer 91. The slotted metal patch 2 is provided on the top surface of the second dielectric layer 92. The feeding microstrip line 39 and the coupling microstrip line 3 are provided on the top surface of the third dielectric layer 93. The metal floor 4 is provided below the third dielectric layer 93, that is, the bottom surface of the third dielectric layer 93 is connected to the metal floor 4. The bottom surface of the second dielectric layer 92 covers the coupling microstrip line 3 and the feeding microstrip line 39 provided on the third dielectric layer 93 and is bonded to the third dielectric layer 93. The bottom surface of the first dielectric layer 91 covers the slotted metal patch 2 provided on the second dielectric layer 92 and is bonded to the second dielectric layer 92. The aforementioned top and bottom surfaces are the upper and lower surfaces of the dielectric layer.

[0035] In this embodiment, the first dielectric layer 91 is made of an insulating dielectric material with a dielectric constant of 1.06 and a loss tangent of 0.0001, with a thickness of H91. The second dielectric layer 92 and the third dielectric layer 93 are made of insulating dielectric materials with a dielectric constant of 2.20 and a loss tangent of 0.0009, with thicknesses of H92 and H93, respectively. Specifically, this embodiment uses Cuming Microwave C-Foam PF-4 as the material for the first dielectric layer 91, and Rogers RT5880 as the material for the second dielectric layer 92 and the third dielectric layer 93. The Cuming Microwave C-Foam PF-4 sheet has a dielectric constant of 1.06 and a loss tangent of 0.0001; the Rogers RT5880 sheet has a dielectric constant of 2.20 and a loss tangent of 0.0009.

[0036] The metal patch 1 is a square sheet with a side length of L1 and a thickness of H1. Four metal pillars 6 are vertically connected to the four corners of the square sheet metal patch 1. The metal pillars 6 are used to expand the low-frequency impedance bandwidth and are arranged in the dielectric body 9, located between the metal patch 1 and the gap metal sheet 2, and connected to the metal patch 1 at the top. The metal pillars 6 are cylindrical with a height of H6 and a diameter of D6. The metal pillars 6 are vertically connected to the metal patch 1, and the distance between the connection point and the edge of the metal patch 1 is D16. In this embodiment, the metal pillars 6 and the metal patch 1 are preferably connected by welding. After the metal pillars 6 and the metal patch 1 are welded, they are integrally formed with the first dielectric layer 91, so that the metal pillars 6 are buried in the first dielectric layer 91 and the metal patch 1 is attached to the surface of the first dielectric layer 91. Since the metal pillars 6 and the first dielectric layer 91 are integrally formed in the first dielectric layer 91, and the metal pillars 6 are welded to the metal patch 1, the metal pillars 6 also serve to fix the metal patch 1.

[0037] In this embodiment, the slotted metal sheet 2 is a square sheet with a side length of L2 and a thickness of H2. The slotted metal sheet 2 is larger than the metal patch 1, and the center of the slotted metal sheet 2 is aligned with the center of the metal patch 1. Specifically, L2>L1. The alignment of the slotted metal sheet 2 and the metal patch 1 means that the distance between the side of the front projection of the metal patch 1 on the slotted metal sheet 2 and the edge of the slotted metal sheet 2 is (L2-L1) / 2. The slots 5 on the slotted metal sheet 2 include a U-shaped slot 51 and an H-shaped slot 52.

[0038] The U-shaped gap 51 includes a bottom gap 511 and two parallel first side gaps 512 of equal length and flush at both ends. The bottom gap 511 perpendicularly connects one end of the two first side gaps 512, so that the bottom gap 511 and the two first side gaps 512 are connected and form a U-shaped structure. The bottom gap 511 and the first side gaps 512 are both parallel to the edges of the gap metal sheet 2. The length of the first side gap 512 is L512, and the distance between the two first side gaps is W512. The distance between the two first side gaps W512 is the same as the length of the bottom gap 511. The gap width of the bottom gap 511 and the first side gaps 512 is the same, both W5. The distance between the bottom gap 511 and the edge of the gap metal sheet 2 is D51, and the distance between the first side gap 512 and the edge of the gap metal sheet 2 is D52. The U-shaped gap 51 is located at the center of the gap metal sheet 2. Specifically, D52 satisfies the condition: D52 = (L2-2×W5-W512) / 2.

[0039] The H-shaped gap 52 is located on the inner side of the U-shaped gap 51, and includes a center seam 521 and two second side seams 522 that are parallel to each other, of equal length, and flush at both ends. The two second side seams 522 are located between the two first side seams 512 and are parallel to the first side seams 512. The center seam 521 vertically connects the two second side seams 522, so that the center seam 521 and the two second side seams 522 form an H-shaped structure. The two second side seams 522 are each equidistant from the adjacent first side seams 512. The length of the second side seam 522 is L522, and the distance between the two second side seams is W522. The distance between the two second side seams W522 is the same as the length of the center seam 521. The center seam 521 and the second side seams 522 have the same gap width, both of which are W5. The distance D53 between the inner end of the second side seam 522 and the bottom seam 511, the distance D54 between the center seam 521 and the inner end of the second side seam 522, and the distance D55 between the second side seam 522 and the adjacent first side seam 512 are equal. This means that the distance D55 between the second side seam 522 and the adjacent first side seam 512 satisfies the following condition: D55 = (W512 - 2 × W5 - W522) / 2. The inner end of the second side seam 522 refers to the end of the second side seam 522 that faces the bottom seam 511.

[0040] The coupling microstrip line 3 is located below the slot 5 and directly opposite the slot 5. In this embodiment, the coupling microstrip line 3 includes a first microstrip line 31 and a second microstrip line 32. The length direction of the first microstrip line 31 is parallel to the first side slots 512 and is located on the central axis between the two first side slots 512. The length direction of the second microstrip line 32 is perpendicular to the first side slots 512 and is located on the central axis between the two first side slots 512. The front projection of the second microstrip line 32 on the slot metal sheet 2 is located inside the U-shaped slot 51. Specifically, the front projection of the second microstrip line 32 on the slot metal sheet 2 does not exceed the rectangular area enclosed by the bottom slot 511, the middle slot 521 and the two first side slots 512. One end of the first microstrip line 31 is connected to the feed microstrip line 39, and the other end is connected to the second microstrip line 32, and forms a T-shaped structure with the second microstrip line 32. More specifically, in this embodiment, the first microstrip line 31 and the feed microstrip line 39 are integrated microstrip lines. The first microstrip line 31 is the portion of the integrated microstrip line that overlaps the slotted metal sheet 2 when projected forward onto the slotted metal sheet 2. The portion extending beyond the slotted metal sheet 2 is the feed microstrip line 39. The length of the first microstrip line 31 is L31, which is the distance between the edge of the second microstrip line 32 and the edge of the slotted metal sheet 2. The width of the first microstrip line is W31, which is also the width of the feed microstrip line 39. The second microstrip line 32 is L32 long and W32 wide.

[0041] In this embodiment, the size parameters are configured as follows:

[0042] The thickness of metal patch 1 is H1 = 0.10 mm, and the side length is L1 = 6.16 mm;

[0043] The thickness of the gap metal sheet 2 is H2 = 0.10 mm, and the side length is L2 = 7.50 mm;

[0044] The gap width W5 of the bottom seam 511, the first side seam 512, the middle seam 521 and the second side seam 522 is 0.15 mm;

[0045] The length L512 of the first side seam 512 is 4.78 mm, and the distance W512 between the two first side seams 512 is 2.85 mm.

[0046] The distance D51 between the bottom seam 511 and the edge of the gap metal sheet 2 is 0.65 mm;

[0047] The distance D52 between the first side seam 512 and the edge of the slotted metal sheet 2 is 2.175 mm;

[0048] The length of the second side seam 522 is L522 = 2.80 mm, and the distance between the two second side seams 522 is W522 = 0.65 mm;

[0049] The distance D53 between the inner end of the second side seam 522 and the bottom seam 511 is 1.79 mm;

[0050] The distance D54 from the middle seam 521 to the inner end of the second side seam 522 is 0.485 mm;

[0051] The distance D55 between the second side seam 522 and the first side seam 512 is 0.95 mm;

[0052] The thickness of the coupled microstrip line 3 is H3 = 0.10 mm;

[0053] The first microstrip line 31 has a length L31 = 1.73 mm and a width W31 = 1.20 mm;

[0054] The first microstrip line 31 has a length L32 = 2.14 mm and a width W32 = 1.48 mm;

[0055] The thickness of the metal floor 4 is H4 = 0.10 mm;

[0056] The thickness of the first dielectric layer 91 is H91 = 3.28 mm;

[0057] The thickness of the second dielectric layer 92 is H92 = 0.51 mm;

[0058] The thickness H93 of the third dielectric layer 93 is 0.51 mm.

[0059] The operating frequency of the antenna of this embodiment under the above-mentioned size parameter configuration is 11G~13GHz, corresponding to a wavelength range of 23.06~27.25mm, a center frequency of 12GHz, and a center wavelength of A=25mm.

[0060] According to the effect of substrate thickness on surface waves, when the substrate thickness satisfies When , the influence of surface waves can be ignored, where T is the thickness of the substrate, A is the wavelength of the electromagnetic wave, In this embodiment, the dielectric constant of the second dielectric layer 92 and the third dielectric layer 93 as the substrate is 2.2. It can be concluded that when the substrate thickness satisfies In this embodiment, in order to minimize the influence of surface waves, the thickness of the second dielectric layer 92 and the third dielectric layer 93 is 0.51 mm, which is equivalent to 0.02 Å.

[0061] Figure 4 The reflection coefficient of the dielectric patch antenna of this embodiment when operating at 11G~13GHz is shown. It can be seen from the figure that the reflection coefficient of the dielectric patch antenna of this embodiment when operating at 11G~13GHz is less than -20dB, especially at 11.2GHz, the reflection coefficient is close to -30dB.

[0062] Figure 5The cross-polarization of the dielectric patch antenna of this embodiment when operating at 11G~13GHz is shown. It can be seen from the figure that the cross-polarization of the dielectric patch antenna of this embodiment when operating at 11G~13GHz is -33dB~-38dB, which is lower than the design requirement of -30dB.

[0063] Figure 6 The figure shows the gain of the dielectric patch antenna of this embodiment when it operates at 11G~13GHz. It can be seen from the figure that the gain of the dielectric patch antenna of this embodiment when it operates at 11G~13GHz is above 6.5dB.

[0064] Figure 7 and Figure 8 The figure shows the spatial gain of the dielectric patch antenna of this embodiment. It can be seen from the figure that the dielectric patch antenna of this embodiment has good antenna gain in the range of -20 degrees to 20 degrees from the front.

Claims

1. A broadband, low-profile, low-cross-polarization dielectric patch antenna, characterized in that: The invention comprises a dielectric body (9), and metal patches (1), slot metal sheets (2), coupling microstrip lines (3), and metal floor (4) arranged on the dielectric body (9) and supported by the dielectric body (9), which are parallel to each other, separated from each other, and stacked in order. The slot metal sheet (2) is provided with a slot (5). The coupling microstrip line (3) is located below the slot (5). The metal patch (1) is a square sheet. Four metal pillars (6) are vertically connected to the four corners of the square sheet metal patch (1). The metal pillars (6) are arranged in the dielectric body (9), between the metal patch (1) and the slot metal sheet (2), and the top ends are connected to the metal patch (1). The coupling microstrip line (3) is connected to the feeding microstrip line (39). The slot (5) includes a U-shaped slot (51) and an H-shaped slot (52). The U-shaped slot ( The invention relates to a method for manufacturing a slit (51) comprising a bottom seam (511) and two first side seams (512) that are parallel to each other and of equal length and flush at both ends; the bottom seam (511) vertically connects one end of the two first side seams (512), so that the bottom seam (511) and the two first side seams (512) are connected and form a U-shaped structure; the H-shaped gap (52) is located inside the U-shaped gap (51), and comprises a middle seam (521) and two second side seams (522) that are parallel to each other and of equal length and flush at both ends; the two second side seams (522) are located between the two first side seams (512) and are parallel to the first side seams (512), and are each equidistant from the adjacent first side seams (512); the middle seam (521) vertically connects the two second side seams (522), so that the middle seam (521) and the two second side seams (522) form an H-shaped structure.

2. The broadband low-profile low cross-polarization dielectric patch antenna according to claim 1, characterized in that: The metal column (6) is connected to the metal patch (1) by welding.

3. The broadband low-profile low cross-polarization dielectric patch antenna according to claim 1, characterized in that: The slot metal sheet (2) is a square sheet; the size of the slot metal sheet (2) is larger than the metal patch (1), and the center of the slot metal sheet (2) is aligned with the center of the metal patch (1).

4. The broadband low-profile low cross-polarization dielectric patch antenna according to claim 1, characterized in that: The dielectric body (9) comprises a first dielectric layer (91), a second dielectric layer (92) and a third dielectric layer (93); the metal patch (1) is arranged on the top surface of the first dielectric layer (91); and the gap metal sheet (2) is arranged on the top surface of the second dielectric layer (92); The feeding microstrip line (39) and the coupling microstrip line (3) are arranged on the top surface of the third dielectric layer (93); the bottom surface of the third dielectric layer (93) is connected to the metal floor (4); the bottom surface of the second dielectric layer (92) covers the coupling microstrip line (3) and the feeding microstrip line (39) arranged on the third dielectric layer (93) and is joined to the third dielectric layer (93); the bottom surface of the first dielectric layer (91) covers the slotted metal sheet (2) arranged on the second dielectric layer (92) and is joined to the second dielectric layer (92).

5. The broadband low-profile low cross-polarization dielectric patch antenna according to claim 4, characterized in that: The dielectric constant of the first dielectric layer (91) is 1.06, and the loss tangent is 0.0001; the dielectric constant of the second dielectric layer (92) is 2.20, and the loss tangent is 0.0009; and the dielectric constant of the third dielectric layer (93) is 2.20, and the loss tangent is 0.0009.

6. The broadband low-profile low cross-polarization dielectric patch antenna according to claim 5, characterized in that: The thickness of the second dielectric layer (92) and the third dielectric layer (93) is 0.02A, where A is the central wavelength of the antenna's operating frequency.

7. The broadband low-profile low cross-polarization dielectric patch antenna according to claim 1, characterized in that: The coupled microstrip line (3) comprises a first microstrip line (31) and a second microstrip line (32); wherein the length direction of the first microstrip line (31) is parallel to the first side seam (512) and is located on the central axis between the two first side seams (512); the length direction of the second microstrip line (32) is perpendicular to the first side seam (512) and is located on the central axis between the two first side seams (512), and its front projection on the gap metal sheet (2) is located inside the U-shaped gap (51); one end of the first microstrip line (31) is connected to the feeding microstrip line (39), and the other end is connected to the second microstrip line (32), and the first microstrip line (31) and the second microstrip line (32) form a T-shaped structure.

8. The broadband low-profile low cross-polarization dielectric patch antenna according to claim 7, characterized in that: The front projection of the second microstrip line (32) on the slot metal sheet (2) does not exceed the rectangular area surrounded by the bottom slot (511), the middle slot (521) and the two first side slots (512).

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