Miniaturized open-cavity broadband antenna based on substrate-integrated waveguide

Abstract

The present invention belongs to the field of microwave antennas. Disclosed is a miniaturized secondary open-cavity broadband antenna based on a substrate-integrated waveguide, the antenna comprising a bottom dielectric substrate and an upper dielectric substrate, wherein a lower surface of the bottom dielectric substrate is provided with a first metal layer; an upper surface of the bottom dielectric substrate is provided with a second metal layer; the second metal layer has a split slit-shaped open-circuit gap, which is a radiating face of the first metal layer, the second metal layer and the bottom dielectric substrate; a plurality of metal columns penetrate the bottom dielectric substrate, and upper and lower ends of the plurality of metal columns are respectively connected to the first metal layer and the second metal layer; a microstrip line feed is connected on the side of the second metal layer that is away from the slit-shaped open-circuit gap; and the upper dielectric substrate is attached to an upper surface of the second metal layer and attached to the split slit-shaped open-circuit gap of the second metal layer. The miniaturized broadband antenna of the present invention covers an X frequency band, and increases an impedance bandwidth under the action of the loading of an open-circuit gap and the number and positions of metal through holes.

Description

A miniaturized open-cavity broadband antenna based on substrate-integrated waveguide Technical Field

[0001] The present invention belongs to the field of microwave antennas, and in particular relates to an open cavity miniaturized broadband antenna based on a substrate integrated waveguide. Background Art

[0002] Antennas are wireless communication devices used to transmit and receive radio signals. Their performance, to a certain extent, determines the quality of the entire communication system. As communication systems evolve, the demand for smaller and wider antennas is increasing. Traditional antennas often suffer from large size, narrow bandwidth, and low efficiency. Miniaturized antennas can meet the needs of more device integration, but they also suffer from a narrow frequency range and are unable to meet broadband applications. Therefore, the design and manufacture of miniaturized broadband antennas has become a key research topic in antenna science and technology.

[0003] Substrate-integrated waveguide antennas (SIWs) offer significant advantages over traditional microstrip and waveguide antennas due to their compact structure, high performance, and ease of manufacturing. However, their high Q factor results in a narrow bandwidth. Under certain conditions, the Q factor of an electrically small antenna is inversely proportional to its bandwidth. Therefore, by partially opening the closed cavity, the energy stored within the SIW cavity can be reduced, thereby lowering the antenna's Q factor and thus increasing its bandwidth.

[0004] Previous research on miniaturized broadband antennas based on substrate-integrated waveguides has yielded limited designs that balance both operating bandwidth and gain. Therefore, developing antennas with both excellent operating bandwidth and gain performance is of great significance. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an open cavity miniaturized broadband antenna based on substrate integrated waveguide, which realizes a new idea of ​​miniaturizing the open SIW back cavity slot antenna into a broadband antenna. By removing some metal columns, the narrowband antenna can be converted into a broadband antenna. The design structure is simple and the effect is obvious.

[0006] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0007] The present invention is a substrate-integrated waveguide (SIW)-based miniaturized open-cavity broadband antenna, covering the X-band. The antenna comprises a bottom dielectric substrate and an upper dielectric substrate. A first metal layer is provided on the lower surface of the bottom dielectric substrate, and a second metal layer is provided on the upper surface of the bottom dielectric substrate. The second metal layer has a split strip-shaped open slot, which serves as the radiation surface for the first metal layer, the second metal layer, and the bottom dielectric substrate. Several metal cylinders penetrate the bottom dielectric substrate, and the upper and lower ends of the metal cylinders are connected to the first and second metal layers, respectively, to form a SIW resonant cavity. A microstrip line feed is connected to the side of the second metal layer away from the strip-shaped open slot, forming a co-excitation waveguide feed structure. The upper dielectric substrate is attached to the upper surface of the second metal layer and attached to the split strip-shaped open slot in the second metal layer. A third metal layer is provided on the upper surface of the upper dielectric substrate.

[0008] A further improvement of the present invention is that the third metal layer is a T-shaped metal patch with two gaps of a width, four metal short-circuit vias are provided on the upper dielectric substrate, and the four metal short-circuit vias penetrate the upper dielectric substrate. The size of the upper dielectric substrate is 1 / 4.5 of the size of the bottom dielectric substrate.

[0009] A further improvement of the present invention is that the strip-shaped open gap and the gap width are consistent, both being 1.55 mm to 1.75 mm.

[0010] A further improvement of the present invention is that: the bottom dielectric substrate on the same side as the microstrip line feed is open, that is, no metal cylinder is provided; the strip open gap on the bottom dielectric substrate on the same side as the microstrip line feed is open, that is, no metal cylinder is provided; and three metal cylinders are provided on both sides of the center of the strip open gap as the symmetry axis on the bottom dielectric substrate on the other side of the microstrip line feed.

[0011] A further improvement of the present invention is that: the impedance of the microstrip line feed and the port are both 50 ohms.

[0012] The working principle of the present invention is as follows: Several metal cylinders penetrate the middle dielectric substrate, connected at both ends to the first and second metal layers, forming a SIW resonant cavity, thereby achieving a low profile. The antenna feeds the resonant cavity through the coplanar waveguide structure of the second metal layer, exciting the open slots in the second metal layer to radiate electromagnetic waves. These waves are coupled to the upper surface of the second dielectric substrate through the slots and four metal short-circuit vias. The shape and position of the patch in the third metal layer are optimized to construct a miniaturized, quadratically open broadband antenna. The entire antenna exhibits excellent radiation performance, with low cross-polarization levels in the E and H planes. The gain curve is flat within the operating frequency range, with a maximum gain of 7.14dBi and a relative bandwidth of 25.86% within the operating frequency range. Compared with other types of SIW broadband antennas, the present invention exhibits superior performance in both relative operating bandwidth and radiation gain within the operating frequency range.

[0013] The beneficial effects of the present invention are:

[0014] (1) The present invention reduces the Q value of the SIW cavity by removing some metal pillars, increases the energy radiation of the side wall, and widens the antenna bandwidth under the action of loading the open circuit gap.

[0015] (2) The present invention introduces a second-layer fully open antenna structure, so that the antenna has a lower cross-polarization level in the process of expanding the bandwidth.

[0016] (3) The present invention proposes a novel design for realizing an open SIW miniaturized broadband antenna. Due to the independence of the parasitic patch, the antenna is simpler than other SIW array broadband antennas. Without adding a complex matching network and special structure, the impedance bandwidth can be improved by simply removing some metal columns.

[0017] (4) The present invention ultimately makes the open SIW miniaturized broadband antenna simpler and easier to process while maintaining good radiation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is a perspective schematic diagram of the present invention.

[0019] FIG2 is a partial top view of the present invention.

[0020] FIG3 is a partial top view of the present invention.

[0021] FIG4 is a diagram of simulated S parameters according to an embodiment of the present invention.

[0022] FIG5 is a simulation gain diagram of an embodiment of the present invention.

[0023] FIG6 is a main polarization and cross-polarization E-plane simulation pattern at 9.7 GHz according to an embodiment of the present invention.

[0024] FIG7 is a main polarization and cross-polarization H-plane simulation pattern at 9.7 GHz according to an embodiment of the present invention.

[0025] FIG8 is a main polarization and cross-polarization E-plane simulation pattern at 10.6 GHz according to an embodiment of the present invention.

[0026] FIG9 is a main polarization and cross-polarization H-plane simulation pattern at 10.6 GHz according to an embodiment of the present invention.

[0027] FIG10 is a main polarization and cross-polarization E-plane simulation pattern of an embodiment of the present invention at 11.75 GHz.

[0028] FIG11 is a main polarization and cross-polarization H-plane simulation pattern of an embodiment of the present invention at 11.75 GHz.

[0029] Among them: 1-first metal layer, 2-second metal layer, 3-third metal layer, 4-bottom dielectric substrate, 6-upper dielectric substrate, 7-microstrip line feed, 8-slot, 9-T-shaped metal patch, 10-metal short-circuit through hole, 11-strip open slot. DETAILED DESCRIPTION

[0030] The following drawings illustrate embodiments of the present invention. For clarity, many practical details are included in the following description. However, it should be understood that these practical details are not intended to limit the present invention. In other words, in some embodiments of the present invention, these practical details are not essential. Furthermore, to simplify the drawings, some commonly used structures and components are depicted in simplified schematic form.

[0031] The present invention provides an open SIW miniaturized broadband antenna. By removing some metal columns from the sidewalls, the energy storage in the SIW cavity is reduced, the Q value of the antenna is lowered, and the bandwidth is widened. In addition, by coupling the gaps and short-circuit vias, a second-layer substrate structure is introduced to reduce the cross-polarization of the antenna and further improve the bandwidth.

[0032] As shown in Figures 1-3, the present invention is an open-cavity miniaturized broadband antenna based on a substrate-integrated waveguide. The open-cavity miniaturized broadband antenna covers the X-band. The open-cavity miniaturized broadband antenna of the present invention includes a bottom dielectric substrate 4 and an upper dielectric substrate 6. The size of the upper dielectric substrate 6 is 1 / 4.5 of the size of the bottom dielectric substrate 4. A first metal layer 1 is provided on the lower surface of the bottom dielectric substrate 4, and a second metal layer 2 is provided on the upper surface of the bottom dielectric substrate 4. The second metal layer 2 has a split strip-shaped open slot 11, which serves as the radiation surface for the first metal layer 1, the second metal layer 2, and the bottom dielectric substrate 4. Several metal cylinders penetrate the bottom dielectric substrate 4, and the upper and lower ends of the several metal cylinders are respectively connected to the first metal layer 1 and the second metal layer 2, forming a SIW resonant cavity. A microstrip line feed 7 is connected to the side of the second metal layer 2 away from the strip-shaped open slot 11, forming a co-excitation waveguide feed structure. The impedance of the microstrip line feed 7 and the port is 50 ohms. The upper dielectric substrate 6 is attached to the upper surface of the second metal layer 2 and attached to the strip open gap 11 cracked in the second metal layer 2. The upper surface of the upper dielectric substrate 6 is the third metal layer 3. The strip open gap 11 is consistent with the width of the gap 8, both of which are 1.55mm-1.75mm, preferably 1.65mm. The open gap couples energy from the bottom layer to the upper layer, reducing the energy leakage of the bottom open cavity. The third metal layer 3 is a T-shaped metal with two gaps 8 of the same width. The patch 9 has four metal short-circuit holes 10 provided on the upper dielectric substrate 6, and the four metal short-circuit holes 10 pass through the upper dielectric substrate 6. The bottom dielectric substrate 4 on the same side as the microstrip line feed 7 is open, that is, no metal cylinder is provided. The strip open gap 11 on the bottom dielectric substrate 4 on the same side as the microstrip line feed 7 is open, that is, no metal cylinder is provided. On the bottom dielectric substrate 4 on the other side of the microstrip line feed 7, three metal cylinders are provided on both sides of the center of the strip open gap 11 as the axis of symmetry.

[0033] The open SIW miniaturized broadband antenna of the present invention is an open structure improved from a closed substrate integrated waveguide cavity. It achieves a combination of miniaturization and broadband without adding complex network feed and design structures, and is easier to integrate with planar circuits, resulting in better practicality.

[0034] The technical solution of the present invention is further described below through specific embodiments:

[0035] In this embodiment, as shown in Figure 1, the open-type SIW miniaturized broadband antenna consists of two dielectric substrates, both made of Rogers 5880 with a dielectric constant of 2.2 and a loss tangent of 0.0009. The thicknesses are 1.575 mm and 0.787 mm, respectively. The bottom dielectric substrate is coated with a third metal layer on the upper surface, and the bottom with the second metal layer on the lower surface. Metal vias are evenly distributed throughout the bottom dielectric substrate. Metal cylinders penetrate the bottom dielectric substrate through the metal vias. The upper dielectric substrate has two T-shaped metal patches with a spacing equal to the width of the open slot on the upper surface, and the lower surface is attached to the upper metal layer of the bottom dielectric substrate. Four metal short-circuit vias are also added to the dielectric substrate. The original closed rectangular cavity SIW slot antenna has an S11≤-10dB frequency range of 10.74 GHz to 10.87 GHz, a relative bandwidth of 1.2%, and a maximum gain of 3.26 dBi within the operating band. After opening, the S11 ≤ -10 dB frequency range was achieved, with three resonant frequencies at 9.7 GHz, 10.6 GHz, and 11.75 GHz. The impedance matching was excellent, and the relative bandwidth reached 25.86%. The gain curve was flat within the operating frequency band, with a maximum gain of 7.14 dBi, demonstrating excellent radiation characteristics.

[0036] Figure 2 shows the main first layer of the antenna structure of the present invention. It is fed by a 50Ω microstrip line. Several metal cylinders extend through the intermediate dielectric substrate, connecting the first and second metal layers at their ends, forming a SIW resonant cavity. The closed cavity is opened by etching open strips in the second metal layer and removing some of the metal cylinders surrounding the strips.

[0037] As shown in FIG3 , which is the second diagram of the main body of the antenna structure of the present invention, it is composed of a dielectric substrate, two metal T-shaped patches on the upper surface, and four metal short-circuit through holes.

[0038] Figure 4 shows the S-parameter simulation results for the open-type SIW miniaturized broadband antenna. The operating frequency range is 9.46 GHz to 12.27 GHz, generating three resonant frequencies at 9.7 GHz, 10.6 GHz, and 11.75 GHz. The antenna exhibits excellent impedance matching and a relative bandwidth of 25.86%.

[0039] Figure 5 shows the simulation gain results of the open SIW miniaturized broadband antenna.

[0040] FIG6 is a main polarization and cross-polarization E-plane simulation pattern of the present invention at 9.7 GHz.

[0041] FIG7 is a main polarization and cross-polarization H-plane simulation pattern of the present invention at 9.7 GHz.

[0042] FIG8 is a main polarization and cross polarization E-plane simulation pattern of the present invention at 10.6 GHz.

[0043] FIG9 is a main polarization and cross-polarization H-plane simulation pattern of the present invention at 10.6 GHz.

[0044] FIG10 is a main polarization and cross-polarization E-plane simulation pattern of the present invention at 11.75 GHz.

[0045] FIG11 is a main polarization and cross-polarization H-plane simulation pattern of the present invention at 11.75 GHz.

[0046] As can be seen from Figures 6, 8, and 10, the ratio of the main polarization to the cross polarization of the antenna of the present invention in the E plane is about 20 dB. As can be seen from Figures 7, 9, and 11, the ratio of the main polarization to the cross polarization of the antenna of the present invention in the H plane is about 40 dB.

[0047] This invention ultimately achieved a miniaturized broadband antenna covering the X-band, achieving a relative bandwidth of 25.86%, a flat gain curve across the frequency band, and a maximum gain of 7.14dBi, demonstrating excellent radiation performance. Starting with a simple open-cavity rectangular substrate integrated waveguide antenna, the invention demonstrated the bandwidth-broadening performance of open-cavity substrate integrated waveguide antennas. Without the addition of complex matching networks or specialized structures, the impedance bandwidth can be increased simply by removing some metal pillars. This simple and low-cost fabrication approach opens up new possibilities for future broadband antenna design.

[0048] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. An open cavity miniaturized broadband antenna based on a substrate integrated waveguide, comprising a bottom dielectric substrate (4) and an upper dielectric substrate (6), wherein a first metal layer (1) is arranged on the lower surface of the bottom dielectric substrate (4), and a second metal layer (2) is arranged on the upper surface of the bottom dielectric substrate (4), characterized in that: The second metal layer (2) has a split strip-shaped open-circuit gap (11) and is the radiation surface of the first metal layer (1), the second metal layer (2) and the bottom dielectric substrate (4); a plurality of metal cylinders penetrate the bottom dielectric substrate (4) and the upper and lower ends of the plurality of metal cylinders are respectively connected to the first metal layer (1) and the second metal layer (2), forming a SIW resonant cavity; a microstrip line feed (7) is connected to the side of the second metal layer (2) away from the strip-shaped open-circuit gap (11) to form a coplanar waveguide feeding structure; an upper dielectric substrate (6) is attached to the upper surface of the second metal layer (2) and to the split strip-shaped open-circuit gap (11) of the second metal layer (2); and a third metal layer (3) is provided on the upper surface of the upper dielectric substrate (6).

2. The open cavity miniaturized broadband antenna based on substrate integrated waveguide according to claim 1, characterized in that: The third metal layer (3) is a T-shaped metal patch (9) with two gaps (8) of a spacing width, and four metal short-circuit through holes (10) are provided on the upper dielectric substrate (6), and the four metal short-circuit through holes (10) penetrate the upper dielectric substrate (6).

3. The open cavity miniaturized broadband antenna based on substrate integrated waveguide according to claim 2, characterized in that: The strip-shaped open-circuit gap (11) has the same width as the gap (8).

4. The open cavity miniaturized broadband antenna based on substrate integrated waveguide according to claim 3, characterized in that: The width of the strip-shaped open-circuit gap (11) and the gap (8) are both 1.55 mm to 1.75 mm.

5. The open cavity miniaturized broadband antenna based on substrate integrated waveguide according to claim 1, characterized in that: The bottom dielectric substrate (4) on the same side as the microstrip line feed (7) is open-processed, i.e., no metal cylinder is provided; the strip open gap (11) on the bottom dielectric substrate (4) on the same side as the microstrip line feed (7) is open-processed, i.e., no metal cylinder is provided; and three metal cylinders are provided on both sides of the bottom dielectric substrate (4) on the other side than the microstrip line feed (7), with the center of the strip open gap (11) as the axis of symmetry.

6. The open cavity miniaturized broadband antenna based on substrate integrated waveguide according to claim 1, characterized in that: The size of the upper dielectric substrate (6) is 1 / 4.5 of the size of the bottom dielectric substrate (4).

7. The open cavity miniaturized broadband antenna based on substrate integrated waveguide according to claim 1, characterized in that: The impedance of the microstrip line feed (7) and the port is 50 ohms.

8. An open cavity miniaturized broadband antenna based on substrate integrated waveguide according to any one of claims 1 to 7, characterized in that: The open cavity miniaturized broadband antenna covers the X-band.

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