A narrow-edge frequency scanning planar antenna with low profile characteristics

Abstract

This invention discloses a narrow-side frequency scanning planar antenna with low profile characteristics, comprising a dielectric substrate, a substrate-integrated waveguide transmission line structure, a balun structure, several metallized vias, multiple rectangular reflective cavities, and multiple fan-shaped dipole radiating elements. The waveguide transmission line structure is symmetrically laid on the upper and lower surfaces of the dielectric substrate. The balun structure is placed on the upper layer of the dielectric substrate, located at both ends of the waveguide transmission line structure. The metallized vias penetrate the dielectric substrate, and a metal layer is laid on the inner surface of the vias, connecting the upper and lower metal layers of the dielectric substrate. The rectangular reflective cavities are located on the upper and lower surfaces of the dielectric substrate, inside the waveguide transmission line structure. The multiple fan-shaped dipole radiating elements are distributed alternately and in opposite directions on the dielectric substrate, and the centers of the fan-shaped dipole radiating elements are connected to the rectangular reflective cavities via rectangular metal strips. This invention has a wide coverage area and high radiation gain, thus ensuring good narrow-side frequency scanning characteristics.

Description

Technical Field

[0001] This invention relates to a microstrip antenna, and more specifically to a narrow-side frequency scanning planar antenna with low profile characteristics. Background Technology

[0002] Frequency-scanning antennas are antennas whose main beam direction changes with the operating frequency in space. Planar frequency-scanning antennas have attracted much attention due to their low profile, low weight, and ease of integration, making them more suitable for the miniaturization and intelligence requirements of modern communication equipment. However, they are limited by low radiation efficiency, low power capacity, and narrow bandwidth, and many problems still need to be addressed by researchers. Narrow-side frequency-scanning planar antennas refer to antennas whose beam scanning area is a narrow plane along the antenna's extension direction. Because the main beam direction is parallel to the antenna plane, conformal design can be achieved in applications such as aviation, radar, satellite, and automotive. They offer advantages such as reducing the antenna system's space ratio, increasing equipment integration, and not compromising the original equipment's aerodynamic characteristics, making them of significant research importance.

[0003] To address the issues of energy leakage and crosstalk in the microwave and millimeter-wave bands, substrate-integrated waveguide transmission line (SIWL) structures have emerged, offering advantages such as low leakage loss, low manufacturing cost, and a closed structure. Many antenna structures can be implemented using SIWL structures. In narrow-side frequency scanning antenna design, end-fire antennas using SIWL structures can be used as antenna radiating elements, achieving frequency scanning through arraying, thereby meeting the application requirements of microwave and millimeter-wave imaging, navigation and positioning, and target recognition.

[0004] Designing and implementing a narrow-side frequency scanning antenna based on a substrate-integrated waveguide transmission line structure is a challenging research problem. While end-fire elements can be used for arraying, with the feed structure placed on a single dielectric substrate to achieve narrow-side scanning, this multi-layer dielectric structure compromises the antenna's low profile and integration, and is also detrimental to mounting, soldering, and low-cost requirements. The challenge for antenna engineers is to achieve a narrow-side frequency scanning antenna based on a substrate-integrated waveguide transmission line structure using only a single dielectric substrate, ensuring both low profile and simple structure, while also guaranteeing high radiation gain and a wide scanning range. Summary of the Invention

[0005] The purpose of this invention is to provide a narrow-side frequency scanning planar antenna with low profile characteristics, which solves the problems of energy leakage and self-interference in the microwave and millimeter-wave bands of frequency scanning antennas.

[0006] The technical solution for achieving the objective of this invention is as follows:

[0007] A narrow-side frequency scanning planar antenna with low profile characteristics includes a dielectric substrate, a substrate integrated waveguide transmission line structure, a balun structure, several metallized vias, multiple rectangular reflective cavities, and multiple fan-shaped dipole radiating elements. The substrate integrated waveguide transmission line structure is symmetrically laid on the upper and lower surfaces of the dielectric substrate. The balun structure is placed on the upper layer of the dielectric substrate, located at both ends of the substrate integrated waveguide transmission line structure, and is axially symmetrical. The metallized vias penetrate the dielectric substrate, and a metal layer is laid on the inner surface of the vias, connecting the upper and lower metal layers of the dielectric substrate. The rectangular reflective cavities... The back cavity is located on the upper and lower surfaces of the dielectric substrate, inside the substrate integrated waveguide transmission line structure. The multiple fan-shaped dipole radiating units are distributed alternately and in opposite directions on the dielectric substrate. The center of each fan-shaped dipole radiating unit is connected to the corresponding rectangular reflective back cavity metal through a rectangular metal strip. Energy is transmitted along the long side of the antenna through the substrate integrated waveguide transmission line structure, and is sequentially coupled into the rectangular reflective back cavity through metallized vias. It is radiated through the connected fan-shaped dipole radiating units. Multiple periodically arranged fan-shaped dipole radiating units are superimposed in space to form the main beam.

[0008] Furthermore, the upper and lower layers of the dielectric substrate each contain 16 rectangular reflective back cavities and 16 sector-shaped dipole radiating units.

[0009] Furthermore, the balun structure consists of a rectangle and a trapezoid, symmetrically distributed on the left and right sides of the antenna, forming an axisymmetric structure.

[0010] Furthermore, the dielectric substrate is a single-layer dielectric substrate with a length of 166 mm, a width of 28.5 mm, and a thickness of 0.508 mm.

[0011] Furthermore, the substrate integrated waveguide transmission line structure consists of multiple waveguide transmission units, with a length of 160mm and a width of 8.5mm.

[0012] Furthermore, the rectangular length of the balun structure is 3mm, the width is 1.58mm, the upper side of the trapezoid is 1.58mm, the lower side is 2.2mm, and the height is 3mm.

[0013] Furthermore, the radius of the metallized via is 0.2 mm, the spacing is 0.6 mm, and the distance from the surrounding metal patch is 0.1 mm.

[0014] Furthermore, the rectangular reflective back cavity has a length of 10mm and a width of 9mm, and is symmetrically distributed on the upper and lower surfaces of the dielectric substrate with a period of 9mm.

[0015] Furthermore, the radius of the sector-shaped dipole radiating unit is 6 mm, the sector interior angle is 70°, and the period is 9 mm.

[0016] Furthermore, the rectangular metal strip has a length of 4mm and a width of 0.5mm.

[0017] Compared with existing technologies, the significant advantages of this invention are as follows: This invention designs and implements a narrow-side frequency scanning planar antenna with low profile characteristics, using a single-layer substrate integrated waveguide transmission line structure 2, which features a planar structure, low cost, and ease of integration; it employs a sector-shaped dipole radiating element as the main radiating structure, widening the operating bandwidth by increasing the sector's inner angle; the main beam is formed by the superposition of 16 radiating elements, and the main beam changes spatially with the operating frequency; a rectangular reflective cavity guides the propagation of the waveguide's fundamental mode and also acts as a reflector, enhancing end-fire radiation and suppressing back-fire; the balun structure serves both as a mode converter and improves the antenna's impedance matching, reducing return loss at the input port; this invention has a wide coverage area and high radiation gain, thus ensuring excellent narrow-side frequency scanning characteristics, and has potential application value in microwave and millimeter-wave imaging, navigation and positioning, target recognition, and other systems. Attached Figure Description

[0018] Figure 1 This is a three-dimensional overall structural diagram of a narrow-side frequency scanning planar antenna with low profile characteristics.

[0019] Figure 2 This is a top view of a narrow-side frequency-scanning planar antenna with low profile characteristics.

[0020] Figure 3 This is a graph showing the reflection curves of a narrow-side frequency-scanning planar antenna with low profile characteristics.

[0021] Figure 4 This is the radiation pattern of each frequency point on the narrow side plane of a narrow-side frequency scanning planar antenna with low profile characteristics.

[0022] Labeling explanation: 1-Ballon structure, 2-Substrate integrated waveguide transmission line structure, 3-Metallized via, 4-Fan-shaped dipole radiating unit, 5-Reflective back cavity, 6-Dielectric substrate. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, the present invention provides a narrow-side frequency scanning planar antenna with low profile characteristics, including a substrate integrated waveguide transmission line structure 2, a balun structure 1, a metallized via 3, a rectangular reflective back cavity 5, and 16 sector dipole radiating elements 4.

[0025] This invention features a compact structure, with the above-mentioned structure fixed on a dielectric substrate 6: the substrate integrated waveguide transmission line structure 2 is symmetrically laid on the upper and lower surfaces of the dielectric substrate 6; the balun structure 1 is placed on the upper layer of the dielectric substrate 6, located at both ends of the substrate integrated waveguide transmission line structure 2, and is axially symmetrical; the metallized via 3 penetrates the dielectric substrate 6, and a metal layer is laid on the inner surface of the via, connecting the upper and lower metal layers of the dielectric substrate 6; the rectangular reflective back cavity 5 is located on the upper and lower surfaces of the dielectric substrate 6 respectively; the 16 fan-shaped dipole radiating units 4 are staggered and oppositely distributed on the dielectric substrate 6, and are connected to the radiating back cavity metal through rectangular metal strips, thereby realizing end-fire radiative feeding.

[0026] In a further embodiment, the dielectric substrate 6 is a single-layer dielectric substrate with a length of 166 mm, a width of 28.5 mm, and a thickness of 0.508 mm.

[0027] In a further embodiment, the substrate integrated waveguide transmission line structure 2 is composed of multiple waveguide transmission units, with a length of 160 mm and a width of 8.5 mm.

[0028] like Figure 1 As shown, the balun structure 1 consists of a rectangle and a trapezoid, symmetrically distributed on the left and right sides of the antenna, forming an axially symmetrical structure. The rectangle has a length of 3mm and a width of 1.58mm, while the trapezoid has a top side of 1.58mm, a bottom side of 2.2mm, and a height of 3mm.

[0029] In a further embodiment, the metallized via 3 has a radius of 0.2 mm, a spacing of 0.6 mm, and a distance of 0.1 mm from the surrounding metal patch. Based on the preset drilling points evenly distributed in the metallized via 3, when drilling, 6 vias are removed on the back side of each reflective cavity 5, and 3 vias are added on the left side of the substrate integrated waveguide transmission line structure 2 corresponding to the center line position of the reflective cavity 5.

[0030] In a further embodiment, the rectangular reflective back cavity 5 has a length of 10 mm and a width of 9 mm, and is symmetrically distributed above and below the dielectric substrate 6 with a period of 9 mm, which can enhance end-emission radiation and suppress back-emission radiation.

[0031] In a further embodiment, the 16 sector-shaped dipole radiation units 4 have a radius of 6 mm, an internal sector angle of 70°, and are staggered on the upper and lower surfaces of the medium with a period of 9 mm. The dipoles are connected to the upper and lower sides of the radiation back cavity by rectangular metal strips, which are 4 mm long and 0.5 mm wide.

[0032] In a further embodiment, when the antenna of the present invention is in operation, the structure is excited by a 50Ω coaxial connector feed method.

[0033] Energy is input through a 50Ω coaxial connector, which is symmetrically installed on both sides of the antenna. One end connects to the energy input, and the other end connects to a 50Ω matching load. The inner core layer of the coaxial connector is connected to the rectangular metal strip of the balun structure 1, and the outer core layer of the coaxial connector is connected to the lower metal layer of the substrate integrated waveguide transmission line structure 2. Energy is transmitted along the long side of the antenna through the substrate integrated waveguide transmission line structure 2, and is sequentially coupled into the radiating back cavity through the metallized vias 3. It is radiated through the connected fan-shaped dipole radiating elements 4. The 16 periodically arranged dipole elements are superimposed in space to form the main beam. When the antenna operates at different frequencies, the direction of the main beam in space changes accordingly.

[0034] On the one hand, such as Figure 2 As shown, the sector-shaped dipole radiating element 4 is the main radiating structure. By increasing the inner angle of the sector, the operating bandwidth can be widened. The radiating back cavity can guide the propagation of the waveguide fundamental mode and also acts as a reflector, enhancing end-fire radiation and suppressing back-fire radiation. The balun structure 1 can both perform mode conversion and improve the impedance matching of the antenna, reducing the return loss at the input port. Figure 3 The graph shows the change in the antenna's reflection coefficient with the operating frequency. As can be seen from the graph, the antenna achieves good impedance matching within the operating frequency band.

[0035] On the other hand, by adding longitudinal metallized vias 3 and eliminating the metallized vias 3 on the left side of the radiating back cavity, electromagnetic waves propagating laterally in the substrate integrated waveguide transmission line structure 2 can be guided to couple to each radiating back cavity, and further transmitted to the dipole radiating unit through the rectangular metal strip connected thereto, realizing end-fire radiation of each radiating unit. The main beam is formed by the superposition of 16 radiating unit arrays, and the main beam in space changes with the operating frequency. Figure 4 As can be seen, the main beam of the antenna scans with frequency in the narrow side plane, covering a wide range and with high radiation gain, thus ensuring good narrow side frequency scanning characteristics.

Claims

1. A narrow-beam frequency scanning planar antenna with low profile characteristics, characterized by, The application relates to a substrate integrated waveguide transmission line structure (2), a balun structure (1), a plurality of metalized vias (3), a plurality of rectangular reflective back cavities (5) and a plurality of fan-shaped dipole radiating units (4); the substrate integrated waveguide transmission line structure (2) is symmetrically laid on the upper and lower surfaces of a dielectric substrate (6); the balun structure (1) is arranged on the upper layer of the dielectric substrate (6) and located at the two ends of the substrate integrated waveguide transmission line structure (2) and is axially symmetric; the metalized via (3) penetrates through the dielectric substrate (6), a metal layer is laid on the inner surface of the through hole, and the upper and lower layers of the dielectric substrate (6) are connected; the rectangular reflective back cavity (5) is located on the upper and lower surfaces of the dielectric substrate (6) and the inner side of the substrate integrated waveguide transmission line structure (2); the plurality of fan-shaped dipole radiating units (4) are alternately and reversely distributed on the dielectric substrate (6), the center of the fan-shaped dipole radiating unit (4) is connected with the corresponding rectangular reflective back cavity (5) through a rectangular metal strip, energy is transmitted along the long side direction of the antenna through the substrate integrated waveguide transmission line structure (2), is sequentially coupled into the rectangular reflective back cavity (5) through the metalized via (3) and is radiated through the connected fan-shaped dipole radiating unit (4), and a plurality of periodically arranged fan-shaped dipole radiating units (4) are superposed into a main beam in space. There are 16 rectangular reflective back cavities (5) and fan-shaped dipole radiating units (4) on the upper and lower layers of the dielectric substrate (6).

2. The narrow-beam frequency scanning planar antenna with low profile characteristics according to claim 1, characterized in that, The balun structure (1) is composed of a rectangle and a trapezoid and is symmetrically distributed on the left and right sides of the antenna and is axially symmetric.

3. The narrow-beam frequency scanning planar antenna with low profile characteristics according to claim 2, characterized in that, The dielectric substrate (6) is a single-layer dielectric substrate, has a length of 166 mm, a width of 28.5 mm and a thickness of 0.508 mm.

4. The narrow-beam frequency scanning planar antenna with low profile characteristics according to claim 3, characterized in that, The substrate integrated waveguide transmission line structure (2) is composed of a plurality of waveguide transmission units and has a length of 160 mm and a width of 8.5 mm.

5. The narrow-beam frequency scanning planar antenna with low profile characteristics according to claim 3, characterized in that, The rectangle of the balun structure (1) has a length of 3 mm and a width of 1.58 mm, the trapezoid has an upper edge of 1.58 mm, a bottom edge of 2.2 mm and a height of 3 mm.

6. The narrow-beam frequency scanning planar antenna with low profile characteristics according to claim 3, characterized in that, The metalized via (3) has a radius of 0.2 mm, a spacing of 0.6 mm and a distance of 0.1 mm from the peripheral metal patch.

7. The narrow-beam frequency scanning planar antenna with low profile characteristics according to claim 3, characterized in that, The rectangular reflective back cavity (5) has a length of 10 mm and a width of 9 mm and is symmetrically distributed on the upper and lower surfaces of the dielectric substrate (6) with a period of 9 mm.

8. The narrow-beam frequency scanning planar antenna with low profile characteristics according to claim 3, characterized in that, The fan-shaped dipole radiating unit (4) has a radius of 6 mm and an inner angle of 70 degrees and has a period of 9 mm.

9. The narrow-beam frequency scanning planar antenna with low profile characteristics according to claim 3, characterized in that, The rectangular metal strip has a length of 4 mm and a width of 0.5 mm.

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