A structure for reducing the profile height of a planar broadband modular array antenna

Abstract

The application discloses a structure for reducing the profile height of a planar broadband modular array antenna and belongs to the technical field of antenna engineering. The structure is composed of a dielectric substrate, a symmetric planar metal structure and a slotted dipole structure. The symmetric planar metal structure in the same dielectric layer as the array unit dipole will excite induced current in the antenna operating frequency band. At this time, it is equivalent to an additional coupling capacitor, which realizes the effect of adjusting impedance matching similar to the wide-angle impedance matching layer without introducing additional profile height. The application has the advantages of simple structure, low cost, low loss and easy processing. In the embodiment, a low-profile planar broadband modular array antenna unit is designed. By comparing the active standing wave ratios of the array unit before and after loading the structure of the application when the side shooting and E-plane / H-plane 60-degree scanning are performed, it is known that the proposed structure has a significant improvement effect on impedance matching without increasing the overall profile of the antenna.

Description

Technical Field

[0001] This invention belongs to the field of antenna engineering technology, specifically relating to wideband wide-angle scanning phased array antennas, and more specifically to a parasitic structure for reducing the profile height of a planar wideband modular phased array antenna. This structure can significantly reduce the profile height of the planar wideband modular phased array antenna while maintaining excellent impedance matching performance. This structure features low cost, low loss, and ease of fabrication. Background Technology

[0002] Wideband wide-angle scanning phased array antennas are widely used in radar and communication systems due to their high gain, wide bandwidth, and large scanning angle. Among them, planar wideband modular array antennas are favored because of their relatively lower profile height. However, in practical applications, planar wideband modular array antennas often use a wide-angle impedance matching layer to achieve wide bandwidth and large scanning angle. The introduction of the matching layer usually increases the profile height, leading to a larger overall size, which becomes unacceptable in some application scenarios. Therefore, designing and implementing a planar wideband modular array antenna with lower profile characteristics has significant engineering value.

[0003] The paper "Low-Profile Planar Ultrawideband Modular Antenna Array LoadedWith Parasitic Metal Strips" discusses two methods to further improve low-profile characteristics. Method 1: Loading a metasurface-based wide-angle impedance matching layer above the planar broadband modular antenna array, this method achieves a lower profile height compared to traditional purely dielectric wide-angle impedance matching layers. Method 2: Loading a metasurface-based wide-angle impedance matching layer below the antenna. The paper combines these two methods, achieving a third-harmonic impedance bandwidth and a large-angle scan of 60 degrees between the E and H planes at a profile height of 0.228 high-frequency wavelengths. While Method 1 reduces the overall profile height, the profile height introduced by its wide-angle impedance matching layer remains high. Method 2, although not introducing additional profile height, has a limited contribution to low-profile characteristics. Summary of the Invention

[0004] Based on the prior art, this invention proposes an antenna element that reduces the profile height of a planar broadband modular array antenna, further reducing the overall profile height of the array antenna. This invention features simple structure, low cost, low loss, and ease of fabrication.

[0005] The technical solution of the present invention is a structure for reducing the profile height of a planar broadband modular array antenna. The structure is a metal pattern on the upper surface of a unit of a phased array antenna. The structure includes a dielectric substrate, a symmetrical planar metal structure, and a slotted dipole structure.

[0006] A symmetrical planar metal structure and a slotted dipole structure are attached to the upper surface of the dielectric substrate.

[0007] The symmetrical planar metal structure occupies a square area located at the lower left corner of the upper surface of the dielectric substrate. The remaining portion of the upper surface of the dielectric substrate houses a slotted dipole structure. The slotted dipole structure comprises six metal sheets: three horizontally and three vertically. Each sheet is surrounded by a parasitic structure, with gaps between the parasitic structure and the surrounding metal sheet. The three horizontally arranged sheets of the slotted dipole structure are located on the upper side of the upper surface of the dielectric substrate. The shape of the leftmost and rightmost sheets combined is the same as the middle sheet. The three vertically arranged sheets are located on the upper side of the upper surface of the dielectric substrate. On the right side of the upper surface, the top and bottom pieces, when spliced ​​together, have the same shape as the middle piece. The horizontal and vertical middle pieces have the same shape, and their positions are rotated 90 degrees to coincide. The center of rotation is the center of the top edge of the four pieces in the upper right corner. The horizontal and vertical middle pieces are hexagonal in shape as a whole, which is formed by splicing the bases of two isosceles trapezoids. The base angles of the two isosceles trapezoids are different, and the top edge of the isosceles trapezoid with the smaller base angle points to the center of rotation. The top edge is correspondingly curved to match the center of rotation. The parasitic structures on the upper surface of adjacent phased array antenna elements are spliced ​​together to form a complete metal sheet.

[0008] Furthermore, in the slotted dipole structure, a semi-circular groove is opened inward on the top edge of the isosceles trapezoidal part with the large base angle in the metal sheet, and the corresponding parasitic structure is a circular patch, with the midpoint of the parasitic structure protruding outward.

[0009] Furthermore, the symmetrical planar metal structure is a square metal sheet arranged in 4 rows and 4 columns.

[0010] Furthermore, the symmetrical planar metal structure is based on a 4x4 square metal sheet, with a slit opened from the midpoint of each side of the metal sheet towards the center of the metal sheet, and the four slits are not connected.

[0011] Furthermore, the symmetrical planar metal structure is based on a 4x4 square metal sheet, with grooves or protrusions on the edges of adjacent metal sheets; one side is provided with a groove, and the corresponding edge of the adjacent metal sheet is provided with a protrusion that matches the groove.

[0012] Furthermore, the symmetrical planar metal structure is a square annular metal sheet arranged in 4 rows and 4 columns.

[0013] The structure of this invention is equivalent to an additional coupling capacitor, achieving an impedance matching effect similar to a wide-angle impedance matching layer without introducing additional profile height. The slotted dipole parasitic structure located inside the antenna element dipole provides an induced current in the opposite direction to the current within the antenna's operating frequency band, replacing the wide-angle impedance matching layer and improving the impact of unbalanced feeding on the high-frequency impedance matching of the antenna. Based on these two points, this invention reduces the profile height of the planar broadband modular array antenna. This invention has the advantages of simple structure, low cost, low loss, and easy fabrication. In the embodiment, a low-profile planar broadband modular array antenna element was designed. Comparing the side-fire and active VSWR of the array element before and after loading the structure described in this invention at a 60-degree E-plane / H-plane scan, it can be seen that the proposed structure significantly improves impedance matching without increasing the overall antenna profile. Attached Figure Description

[0014] Figure 1 Figure (a) is a front view and a 3D view of the unit of the parasitic structure of the invention, and Figure (b) is a 3D view of the unit.

[0015] Figure 2 It was a partial replacement. Figure 1 The remaining forms of planar metal structures of the symmetrical planar metal structure.

[0016] Figure 3 This is a schematic diagram of a planar broadband modular phased array antenna unit without the symmetrical planar metal structure and the slotted dipole structure described in this invention.

[0017] Figure 4 This is a schematic diagram of a planar broadband modular phased array antenna element loaded with the symmetrical planar metal structure described in this invention, but without the slotted dipole structure.

[0018] Figure 5 This is a schematic diagram of a planar broadband modular phased array antenna unit loaded with the symmetrical planar metal structure and the slotted dipole structure described in this invention.

[0019] Figure 6 These are the active VSWR curves of the antenna element under side-firing and 60-degree scanning of the E-plane / H-plane without loading the symmetrical planar metal structure and the slotted dipole structure described in this invention.

[0020] Figure 7 These are the active VSWR curves of the antenna element side-fired and E-plane / H-plane 60-degree scan when the symmetrical planar metal structure described in this invention is loaded, but the slotted dipole structure is not loaded.

[0021] Figure 8 These are the active VSWR curves of the antenna element under side-firing and 60-degree scanning of the E-plane / H-plane when the symmetrical planar metal structure and the slotted dipole structure described in this invention are loaded.

[0022] Figure 9 These are the port isolation curves for the antenna element side-firing and the 60-degree scanning port on the E-plane / H-plane when the symmetrical planar metal structure and the slotted dipole structure described in this invention are loaded. Detailed Implementation

[0023] Example 1.

[0024] The parasitic structure model diagram for reducing the profile height of the planar broadband modular array antenna in this embodiment is shown below. Figure 1 As shown. The antenna layer dielectric substrate material is F4BM350, with a thickness of 0.25 mm and a relative permittivity of 3.5. Figure 1 As shown in (b), Structure 1 is a symmetrical planar metal structure printed on the front side of the antenna layer dielectric substrate. Structure 1 consists of 4*4 square metal patches with rectangular slots, each patch measuring 3.28mm*3.28mm. The rectangular slot inside each patch measures 0.15mm*1.3mm. The spacing between the patches is 0.15mm. Structure 2 is a slotted dipole structure printed on the same dielectric substrate, located inside the antenna dipole structure, with a slot width of 0.2mm.

[0025] The symmetrical planar metal structure is attached above / below / on both sides of the dielectric substrate and is positioned at a certain distance from the antenna dipole. The symmetrical planar metal structure is symmetrical when viewed from the two polarization directions of the antenna. During antenna operation, the symmetrical planar metal structure induces a current. For the antenna, the symmetrical planar metal structure acts as an additional coupling capacitor, achieving an impedance matching effect similar to a wide-angle impedance matching layer without introducing additional profile height. The slotted dipole structure, located inside the antenna dipole, provides an induced current in the opposite direction to the dipole, replacing the wide-angle impedance matching layer and improving the impact of the unbalanced feed structure on the high-frequency impedance matching of the antenna.

[0026] Figure 2 Schematic diagrams of other types of symmetrical planar metal structures are shown, all of which can adjust impedance matching without introducing additional cross-sectional height. The symmetrical planar metal structure proposed in this invention has shapes including, but not limited to, those shown. Figure 2 The displayed shapes include 4x4 rectangular tiles, 3x3 rectangular tiles, 4x4 interlaced tiles, and 4x4 loop tiles.

[0027] To verify the performance of the parasitic structure proposed in this invention, a planar broadband modular array antenna with a working bandwidth of 3:1 was designed for verification. Its unit schematic diagram is shown below. Figure 3 As shown. The unit size is 25mm*25mm. The cross-sectional height of the unit is 9.65mm, which is 0.193 high-frequency wavelengths.

[0028] Figure 4 This is a schematic diagram of a planar broadband modular phased array antenna element loaded with the symmetrical planar metal structure described in this invention, but without the slotted dipole structure.

[0029] Figure 5 This is a schematic diagram of a planar broadband modular phased array antenna element loaded with the symmetrical planar metal structure and the slotted dipole structure described in this invention. The symmetrical planar metal structure 3 is printed on the front side of the antenna layer dielectric substrate 4, maintaining a certain distance from the antenna dipole 5. The slotted dipole structure 6 is also printed on the antenna layer dielectric substrate 4 and is located inside the antenna dipole 5.

[0030] Figure 6 These are the active VSWR curves of the antenna side-firing and E-plane / H-plane 60-degree scanning when the symmetrical planar metal structure and the slotted dipole structure described in this invention are not loaded, where fL is the lowest operating frequency of this array.

[0031] Figure 7 The active VSWR curves are for side-fired antenna and 60-degree E-plane / H-plane scanning when the symmetrical planar metal structure described in this invention is loaded, but the slotted dipole structure is not loaded. In this case, the active VSWR for 60-degree H-plane scanning is improved within the range of fL-3fL. However, for both side-fired antenna and 60-degree E-plane scanning, the active VSWR deteriorates overall within the range of fL-3fL.

[0032] Figure 8 These are the active VSWR curves of the antenna under side-firing and 60-degree scanning of the E-plane / H-plane when the symmetrical planar metal structure and the slotted dipole structure described in this invention are loaded. At this time, the active VSWR of the antenna is less than 3 in the fL-3fL operating frequency band.

[0033] Figure 9 The figures show the antenna side-firing and E-plane / H-plane 60-degree scanning port isolation curves when the symmetrical planar metal structure and the slotted dipole structure described in this invention are loaded. As can be seen from the figures, within the fL-3fL operating frequency band, all antenna elements in the array exhibit good port isolation.

[0034] The above comparative analysis shows that the parasitic structure described in this invention can effectively improve the impedance matching of the planar broadband modular array antenna during side firing and 60-degree scanning of the E-plane / H-plane at a lower profile height.

Claims

1. A structure for reducing the profile height of a planar broadband modular array antenna, the structure being a metal pattern on the upper surface of an element of a phased array antenna, the structure comprising a dielectric substrate, a symmetrical planar metal structure, and a slotted dipole structure; A symmetrical planar metal structure and a slotted dipole structure are attached to the upper surface of the dielectric substrate. The symmetrical planar metal structure occupies a square area located at the lower left corner of the upper surface of the dielectric substrate. The remaining portion of the upper surface of the dielectric substrate houses a slotted dipole structure. The slotted dipole structure comprises six metal sheets: three horizontally and three vertically. Each sheet is surrounded by a parasitic structure, with gaps between the parasitic structure and the surrounding metal sheet. The three horizontally arranged sheets of the slotted dipole structure are located on the upper side of the upper surface of the dielectric substrate. The shape of the leftmost and rightmost sheets combined is the same as the middle sheet. The three vertically arranged sheets are located on the upper surface of the dielectric substrate. On the right side of the surface, the top and bottom pieces, when spliced ​​together, have the same shape as the middle piece. The horizontal and vertical middle pieces have the same shape, and their positions are rotated 90 degrees to coincide. The center of rotation is the center of the top edge of the four metal pieces in the upper right corner. The horizontal and vertical middle pieces are hexagonal in shape as a whole, which is formed by splicing the bases of two isosceles trapezoids. The base angles of the two isosceles trapezoids are different, and the top edge of the isosceles trapezoid with the smaller base angle points to the center of rotation. The top edge is correspondingly curved to match the center of rotation. The parasitic structures on the upper surface of adjacent phased array antenna elements are spliced ​​together to form a complete metal piece.

2. The structure for reducing the profile height of a planar broadband modular array antenna as described in claim 1, characterized in that, In the slotted dipole structure, a semi-circular groove is opened inward on the top edge of the isosceles trapezoidal part with the large base angle in the metal sheet. The corresponding parasitic structure is a circular patch, and the midpoint of the parasitic structure protrudes outward.

3. The structure for reducing the profile height of a planar broadband modular array antenna as described in claim 1, characterized in that, The symmetrical planar metal structure consists of 4 rows and 4 columns of square metal sheets.

4. The structure for reducing the profile height of a planar broadband modular array antenna as described in claim 1, characterized in that, The symmetrical planar metal structure is based on a square metal sheet arranged in 4 rows and 4 columns, with a slit opened from the midpoint of each side of the metal sheet towards the center of the metal sheet, and the four slits are not connected.

5. The structure for reducing the profile height of a planar broadband modular array antenna as described in claim 1, characterized in that, The symmetrical planar metal structure is based on a 4x4 square metal sheet, with grooves or protrusions on the edges of adjacent metal sheets; if a groove is provided on one side, a protrusion that matches the groove is provided on the corresponding edge of the adjacent metal sheet.

6. The structure for reducing the profile height of a planar broadband modular array antenna as described in claim 1, characterized in that, The symmetrical planar metal structure is a square ring-shaped metal sheet arranged in 4 rows and 4 columns.

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