High-efficiency dual-polarized co-axial slot leaky-wave antenna with suppressed open-circuit stopband

Abstract

The application belongs to the technical field of antennas, and particularly relates to a high-efficiency dual-polarized co-aperture slot leaky-wave antenna for suppressing open-circuit stop band. The antenna comprises a substrate integrated waveguide, and the substrate integrated waveguide is provided with a first metal layer, a second metal layer and a third metal layer. The first metal layer is provided with longitudinal slots for radiating X-direction polarized waves and transverse slots for radiating Y-direction polarized waves. The second metal layer is provided with a series feeding network. The series feeding network is composed of a power divider and a strip-line feeding structure. By adding the strip-line feeding structure parallel to the waveguide wide surface in the substrate integrated waveguide, a TEM mode is introduced. The TEM mode of the strip-line feeding structure excites the longitudinal longitudinal slots in the center of the substrate integrated waveguide and the transverse slots in the TE10 mode, so that the dual-polarized antenna in the same aperture is realized. The series feeding network structure is combined with the slots to form a series feeding traveling-wave antenna, so that the bandwidth of the antenna is greatly expanded.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically a high-efficiency dual-polarized common-aperture slot leaky wave antenna that suppresses open-circuit stopband. Background Technology

[0002] Antennas, as devices for transmitting and receiving electromagnetic waves, play a crucial role in communication systems. Depending on the application scenario and performance requirements, antennas are classified into various types, with slot array antennas being one of them. Slot array antennas use a periodically arranged leaky slot structure to radiate electromagnetic waves into space, exhibiting excellent directivity. As the operating frequency changes, the beam direction shifts accordingly. These characteristics endow slot array antennas with a series of advantages, including low cost, high gain, and beam scanning, making them widely used in the millimeter-wave band.

[0003] A dual-polarized antenna is an antenna capable of transmitting and receiving electromagnetic waves in two mutually perpendicular directions. Its key feature is its dual-directional transmission and reception capability, allowing it to simultaneously transmit signals with two different polarization directions. Primarily used in communication, radar, and navigation systems, it is an indispensable key component of modern wireless communication technology.

[0004] Traditional dual-polarized antenna arrays can employ antennas such as dipole antennas, whose feeding networks typically use parallel feeding, resulting in complex overall antenna structures and dimensions, and relatively high profiles. However, using waveguide structures, such as rectangular waveguides or substrate-integrated waveguide slotted array antennas, typically makes it difficult to implement dual-polarized antennas and results in narrower bandwidths.

[0005] Research on the communication characteristics of the millimeter wave band has attracted much attention from scholars. Its advantages are mainly reflected in high communication rate and wide available channel bandwidth. However, due to the short wavelength of this band, it is more susceptible to environmental interference, but this can be effectively improved by using dual-polarized antennas.

[0006] For example, in his 2020 master's thesis, "Research on Leaky Wave Antenna Based on Substrate Integrated Waveguide," Sun Shi'en of Tianjin University of Technology designed a circularly polarized open-stopband suppressed leaky wave slot array antenna. This antenna, based on a substrate integrated waveguide structure, is very compact and can achieve beam scanning from -29° to 32° when the operating frequency varies from 10 to 13 GHz, exhibiting good open-stopband suppression. However, the rich modes within this substrate integrated waveguide have not been fully utilized, covering only one operating frequency band, thus indicating remaining development potential.

[0007] For example, in 2021, Xu Yechun from South China University of Technology designed a dual-polarized waveguide slot array antenna based on a substrate integrated waveguide in Chapter 4 of his master's thesis, "Millimeter-Wave Waveguide Slot Single-Polarized and Dual-Polarized Array Antennas." The antenna shared the same aperture surface. It had an impedance bandwidth of approximately 2%, good efficiency, a cross-polarization ratio of less than -22 dBi, and an isolation greater than 30 dB. However, the antenna's bandwidth was relatively narrow, making it unsuitable for broadband applications. Summary of the Invention

[0008] To address the shortcomings of the existing technologies, this invention proposes a high-efficiency dual-polarized common-aperture slot leaky wave antenna that suppresses open-circuit stopbands. This antenna can independently control two radiation beams with the same frequency but different polarization directions, and has advantages such as low cost, high aperture efficiency, strong anti-interference capability, and wide applicability.

[0009] The technical solution adopted in this invention is as follows: A high-efficiency dual-polarized common-aperture slotted leaky antenna for suppressing open-circuit stopband includes a first metal layer, an upper dielectric substrate, a second metal layer, a lower dielectric substrate, and a third metal layer arranged sequentially from top to bottom. The upper dielectric substrate has N metallized vias that penetrate the upper dielectric substrate, the first metal layer, the second metal layer, the lower dielectric substrate, and the third metal layer to form a rectangular substrate integrated waveguide cavity. An antenna array is loaded on the first metal layer; the antenna array includes N longitudinal slots for radiating X-direction polarized waves, and the N longitudinal slots are equally spaced along the Y direction; each longitudinal slot is followed by a transverse slot for radiating Y-direction polarized waves. The second metal layer is provided with a series power divider, which consists of a 1-to-N series power divider and N strip lines. One end of each of the N strip lines is connected to one output terminal of the series power divider, and the other end is connected to a longitudinal slot. The third metal layer is a ground plane with two power feeding interfaces, namely an X-direction polarized wave power feeding interface and a Y-direction polarized wave power feeding interface. The X-direction polarized wave power feeding interface passes through the lower dielectric substrate and is connected to the series power divider. The Y-direction polarized wave power feeding interface passes through the lower dielectric substrate and is connected to the second metal layer.

[0010] Furthermore, the power supply interface is a coaxial power supply interface.

[0011] Furthermore, the longitudinal slot adopts a dumbbell-shaped slot structure.

[0012] Furthermore, the intervals between two adjacent sets of longitudinal gaps and between two adjacent sets of transverse gaps are both equal.

[0013] Furthermore, the transverse gaps employ two types of radial structures, namely a first radial structure and a second radial structure. The first radial structure consists of two parallel rectangular gaps, while the second radial structure consists of a dumbbell-shaped gap. Along the Y direction, the first transverse gaps all employ the first radial structure, while the last gap employs the second radial structure.

[0014] Furthermore, n ≥ 3, preferably 8.

[0015] Furthermore, the stripline is an inverted L-shaped structure consisting of a short side and a long side connected together, with one end of the long side of the inverted L connected to the output terminal of the power divider.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention employs two independent orthogonal feeding modes: the TE10 mode of the substrate integrated waveguide feeds the transverse slots, while the TEM mode of the stripline feeds the longitudinal slots. Since the longitudinal slots are symmetrically positioned at the center of the substrate integrated waveguide, they do not radiate in the TE10 mode, thus having no impact on the TE10 mode. This allows for independent control of two radiation beams with the same frequency but different polarizations, improving communication anti-interference capabilities and expanding its application range.

[0017] 2. The antenna array of this invention employs slotted array radiation in both polarization radiation directions and is used in the 28GHz millimeter-wave band. Using a series-fed power divider as the antenna array's feeding structure reduces cost and effectively decreases the antenna array's size. Furthermore, it allows for the expansion of dual-polarized antennas into two-dimensional planar arrays.

[0018] 3. The two polarization radiation slots of the array antenna of the present invention share the same aperture surface. With the TE10 mode and TEM mode feeding, the aperture utilization efficiency is improved, making it suitable for use in communication systems and reducing system complexity. The longitudinal and transverse slots are reasonably arranged, making the field distribution on the antenna array surface relatively uniform, satisfying the condition of equal amplitude and in-phase, and further improving the aperture efficiency.

[0019] 4. The Y-polarized radiation structure of the slot array antenna of the present invention consists of seven groups of double-slot radiation structures, with the last group being a single-slot structure, forming a resonant leaky wave antenna. By adjusting the slot size, controlling the phase shift, and regulating the S-parameters, the open-circuit stopband effect is effectively suppressed. Meanwhile, the X-polarized longitudinal slot radiation structure effectively suppresses the open-circuit stopband effect through a well-matched design of the series-fed power divider at the in-phase radiation frequency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the substrate and metal layer distribution of a high-efficiency dual-polarized common-aperture slot leaky wave antenna as an example. Figure 2 This is a schematic diagram of the first metal layer structure of the high-efficiency dual-polarized common-aperture slot leaky wave antenna in an embodiment. Figure 3 This is a schematic diagram of the second metal layer structure of the high-efficiency dual-polarized common-aperture slot leaky wave antenna in an embodiment. Figure 4 This is a schematic diagram of the third metal layer structure of a high-efficiency dual-polarized common-aperture slotted leaky wave antenna as an example. Figure 5 Simulation results of S-parameters for a high-efficiency dual-polarized common-aperture slotted leaky wave antenna for an example embodiment; Figure 6 The radiation pattern of the co- / cross-polarized E / H planes during X-polarized radiation is shown in the example of a high-efficiency dual-polarized common-aperture slot leaky wave antenna. Figure 7 The radiation pattern of the co- / cross-polarized E / H planes during Y-polarized radiation is shown in the example of a high-efficiency dual-polarized common-aperture slot leaky wave antenna. Figure label: 1. First metal layer; 2. Upper dielectric substrate; 3. Second metal layer; 4. Lower dielectric substrate; 5. Third metal layer; 6. Longitudinal slot; 7. First slot; 8. Second slot; 9. Metallized via; 10. X-direction polarized wave feed interface; 11. Y-direction polarized wave feed interface; 12. Series-connected power divider. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] This embodiment provides a high-efficiency dual-polarized common-aperture slot leaky antenna that suppresses open-circuit stopbands, such as... Figure 1 As shown, the substrate includes an upper dielectric substrate 2 and a lower dielectric substrate 4, with the upper dielectric substrate 2 stacked on the lower dielectric substrate 4. A first metal layer 1 is provided on the upper surface of the upper dielectric substrate 2, a second metal layer 3 is provided between the upper dielectric substrate 2 and the lower dielectric substrate 4, and a third metal layer 5 is provided on the lower surface of the lower dielectric substrate.

[0023] The upper dielectric substrate 2 has seven metallized vias that penetrate the upper dielectric substrate 2, the first metal layer 1, the second metal layer 3, the lower dielectric substrate 4, and the third metal layer 5, forming a rectangular substrate integrated waveguide cavity. The metallized vias are equivalent to electric walls, forming a TE10 mode inside.

[0024] like Figure 2As shown, an antenna array is loaded on the first metal layer. The antenna array includes eight longitudinal slots 6 for radiating X-direction polarized waves. The eight longitudinal slots 6 adopt a dumbbell-shaped slot structure and are equally spaced along the Y direction. After each longitudinal slot, there is a transverse slot for radiating Y-direction polarized waves. The transverse slots adopt two slot structures: a first slot structure 7 and a second slot structure 8. The first slot structure 7 consists of two parallel rectangular slots, and the second slot structure 8 consists of a dumbbell-shaped slot. Along the Y direction, the first seven groups of transverse slots all adopt the first slot structure 7, and the last group of transverse slots adopts the second slot structure 8. According to the principle of series feeding and linear array synthesis, by adjusting the size parameters of the slots in each group, they are made to meet the requirements of uniform energy radiation. The phase difference between two adjacent groups of radiating structures is 360°, and the spacing is one waveguide wavelength, so as to realize the radiation pattern of normal radiation and suppress the open stopband effect.

[0025] like Figure 3 As shown, a series-fed power divider is provided on the second metal layer 3. The series-fed power divider consists of a 1-to-8 series-fed power divider 12 and eight striplines. The input terminal of the series-fed power divider 12 is connected to the X-direction polarized wave feed interface 10, and each output terminal is connected to a stripline. One end of each stripline is connected to a longitudinal slot 6. In this embodiment, the stripline is an inverted L structure composed of a short side and a long side connected together. One end of the long side of the inverted L is connected to the output terminal of the series-fed power divider 12.

[0026] like Figure 4 As shown, the third metal layer 5 is a ground plane; the lower dielectric substrate 4 also has eight metallized vias 9, which coincide vertically with the eight vias on the upper dielectric substrate 2 and penetrate the lower dielectric substrate 4 and the third metal layer 5. The third metal layer 5 has two coaxial power supply interfaces. The two coaxial power supply interfaces are X-direction polarized wave power supply interface 10 and Y-direction polarized wave power supply interface 11, respectively; the X-direction polarized wave power supply interface 10 passes through the lower dielectric substrate 4 and is connected to the series power divider 12; the Y-direction polarized wave power supply interface 11 is located at one end of the central axis of the dielectric substrate and passes through the lower dielectric substrate 4 and is connected to the second metal layer 3 on the lower surface of the upper dielectric substrate 2.

[0027] In this embodiment, eight metallized vias 9 are located near the series-fed power divider 12, arranged sequentially along the long side of the substrate integrated waveguide. The first via on the same side as the Y-direction polarized wave feed interface 11 extends to the edge. Gaps are left between adjacent metallized vias to allow the X-polarized feed network to pass through.

[0028] In use, energy enters the series-fed power divider from the X-polarized wave feed interface 10 and is evenly divided into eight parts, with a phase difference of 360° between adjacent ports. Since the second slot 8 forming the SIW cavity penetrates the substrate, it is still represented in this layer.

[0029] Figure 5 The simulation results of the S-parameters of this common-aperture slot array antenna are as follows: Figure 5 As shown, at 28GHz, the return loss of the Y-direction polarized wave feed interface is -18.47dB, the return loss of the X-direction polarized wave feed interface is -17.69dB, and the isolation between the two ports is -29.71dB.

[0030] Figure 6 This is the radiation pattern of the common / cross-polarized E / H planes of the slot array antenna in this invention during X-polarized radiation. Only the X-direction polarized wave feed interface is excited, while the Y-direction polarized wave feed interface is connected to a matched load. The maximum radiation gain is 15.05 dBi, and the cross-polarization suppression ratio is 21.93 dB.

[0031] Figure 7 This is the radiation pattern of the common / cross-polarized E / H planes of the slot array antenna in this invention during X-polarized radiation. Only the Y-direction polarized wave feed interface is excited, while the X-direction polarized wave feed interface is connected to a matched load. The maximum radiation gain is 15.07 dBi, and the cross-polarization suppression ratio is 24.25 dB. From... Figure 6 and Figure 7 As can be seen from the radiation patterns, the E-plane radiation patterns of X / Y polarization both show the maximum radiation gain in the normal direction, without any gain decrease, indicating that the open stopband effect is effectively suppressed.

[0032] In summary, the high-efficiency dual-polarized common-aperture slotted leaky wave antenna with suppressed open-circuit stopband in this embodiment introduces a TEM mode by adding a stripline parallel to the wide surface of the waveguide into the substrate integrated waveguide. A longitudinal slot for radiating X-polarized waves and a transverse slot for radiating Y-polarized waves are provided on the first metal layer; a series-fed power divider is provided on the second metal layer; the series-fed power divider consists of a 1-to-N power divider and the stripline. The TEM mode of the stripline excites the longitudinal slot with symmetrical openings at the center of the substrate integrated waveguide, and the TE10 mode excites the transverse slot, achieving a dual-polarized antenna with the same aperture. By stitching the series-fed power divider with the slots, a series-fed traveling-wave antenna is formed, significantly expanding the antenna bandwidth. During implementation, an unreasonable spacing between adjacent slots in the same polarization of the traveling wave antenna led to an open-circuit stopband, preventing the antenna from achieving normal radiation. This embodiment addresses this issue by controlling the spacing between adjacent sets of slots to achieve good matching between the slots in the two polarization directions and the series-connected power divider at the normal radiation frequency (f0), effectively suppressing the open-circuit stopband problem in the traveling wave antenna. Furthermore, by controlling the ratio and leakage rate of the series-connected power divider and the traveling wave antenna elements, the entire antenna array achieves an equal-amplitude and in-phase aperture field distribution, improving the antenna's aperture efficiency.

Claims

1. A high-efficiency dual-polarized common-aperture slot leaky wave antenna that suppresses open-circuit stopband, characterized in that, It includes a first metal layer, an upper dielectric substrate, a second metal layer, a lower dielectric substrate, and a third metal layer arranged sequentially from top to bottom. The upper dielectric substrate has N metallized vias that penetrate the upper dielectric substrate, the first metal layer, the second metal layer, the lower dielectric substrate, and the third metal layer to form a rectangular substrate integrated waveguide cavity. An antenna array is loaded on the first metal layer; the antenna array includes N longitudinal slots for radiating X-direction polarized waves, and the N longitudinal slots are equally spaced along the Y direction; each longitudinal slot is followed by a transverse slot for radiating Y-direction polarized waves. The second metal layer is provided with a series power divider, which consists of a 1-to-N series power divider and N strip lines. One end of each of the N strip lines is connected to one output terminal of the series power divider, and the other end is connected to a longitudinal slot. The third metal layer is a ground plane with two power feeding interfaces, namely an X-direction polarized wave power feeding interface and a Y-direction polarized wave power feeding interface. The X-direction polarized wave power feeding interface passes through the lower dielectric substrate and is connected to the series power divider. The Y-direction polarized wave power feeding interface is disposed on the third metal layer and passes through the lower dielectric substrate and is connected to the second metal layer.

2. The high-efficiency dual-polarized common-aperture slotted leaky antenna for suppressing open-circuit stopbands according to claim 1, characterized in that: The power supply interface is a coaxial power supply interface.

3. The high-efficiency dual-polarized common-aperture slotted leaky antenna for suppressing open-circuit stopbands according to claim 1, characterized in that: The longitudinal slot adopts a dumbbell-shaped slot structure.

4. The high-efficiency dual-polarized common-aperture slot leaky antenna for suppressing open-circuit stopband as described in claim 1, characterized in that: The intervals between two adjacent longitudinal slits and between two adjacent transverse slits are both waveguide wavelengths at the center frequency.

5. A high-efficiency dual-polarized common-aperture slotted leaky antenna for suppressing open-circuit stopbands according to claim 1, characterized in that: The transverse gaps employ two types of radial structures: a first radial structure and a second radial structure. The first radial structure consists of two parallel rectangular gaps, while the second radial structure consists of a dumbbell-shaped gap. Along the Y direction, the first seven transverse gaps all use the first radial structure, while the last gap uses the second radial structure.

6. The high-efficiency dual-polarized common-aperture slot leaky antenna for suppressing open-circuit stopband as described in claim 1, characterized in that: The stripline is an inverted L-shaped structure consisting of a short side and a long side connected together, with one end of the long side of the inverted L connected to the output terminal of the series power divider.

7. A high-efficiency dual-polarized common-aperture slotted leaky antenna for suppressing open-circuit stopbands according to claim 1, characterized in that: The value of N is 8.

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