A microwave and millimeter-wave circularly polarized antenna based on SIW circular cavity

Abstract

This invention discloses a microwave and millimeter-wave circularly polarized antenna based on a SIW circular cavity, comprising a first dielectric substrate, a second dielectric substrate, a millimeter-wave radiating patch, a microwave radiating patch, a microwave feed patch, a metal via, a millimeter-wave SIW circular cavity, a metal ground plane, a microwave feed probe, a microwave feed network, and a millimeter-wave feed network. The upper surface of the first dielectric substrate is printed with the millimeter-wave radiating patch, the microwave radiating patch, and the microwave feed patch. The millimeter-wave radiating patch has a radiating slot, and the microwave feed patch and the microwave radiating patch are connected. The second dielectric substrate is located directly below the first dielectric substrate. The upper surface of the second dielectric substrate is printed with a metal ground plane, and feed slots and feed circular holes for the microwave feed probe to pass through are etched on the metal ground plane. The lower surface of the second dielectric substrate is printed with the microwave feed network and the millimeter-wave feed network. This invention has advantages such as multi-frequency operation, wide bandwidth, and dual circular polarization, and has certain potential in wireless communication applications.

Description

Technical Field

[0001] This utility model relates to the technical field of communication antennas, and in particular to a microwave millimeter-wave circularly polarized antenna based on a SIW circular cavity. Background Technology

[0002] With the rapid development of wireless communication technology, modern communication systems place higher demands on antenna performance. Millimeter-wave bands have seen increased exploration and application, while microwave bands remain irreplaceable in many current applications. Therefore, cross-band antennas capable of operating simultaneously in both microwave and millimeter-wave bands can effectively meet the needs of many current applications. Furthermore, circularly polarized antennas are widely used in satellite communication, radar detection, and 5G / 6G mobile communication due to their advantages in effectively suppressing multipath interference, reducing polarization mismatch loss, and improving communication link stability. Therefore, designing a circularly polarized antenna capable of operating simultaneously in both microwave and millimeter-wave bands is a key research topic.

[0003] An investigation and understanding of existing microwave and millimeter-wave dual-frequency antenna technologies was conducted, as detailed below:

[0004] In 2020, Zhen-Xing Xia et al. proposed a dual-fed, dual-band shared-aperture antenna array with a high frequency ratio. Its antenna elements consist of a microwave patch antenna and a 2×2 millimeter-wave slotted antenna subarray etched onto the top surface of the substrate integrated cavity. The patch antenna and the slotted subarray are fabricated on different substrate layers, achieving a shared aperture for two frequency bands. This antenna covers the 5.69–5.89 GHz and 28.47–29.82 GHz bands, with peak gains of 10.9 dBi and 18.7 dBi, respectively, while their in-band isolation exceeds 32 dB.

[0005] In 2021, Yu Qing Guo et al. proposed a single-port, single-layer, dual-band antenna with a high frequency ratio to support microwave and millimeter-wave applications. The antenna mainly consists of a short-line loaded microstrip line at the center, two slotted rectangular patches on the sides, and two fine striplines connecting the two in the middle. The short-line loaded microstrip line serves as the feed line for the series-fed millimeter-wave linear array at 26 GHz, and also as the feed line for the microwave patches operating at 4.85 GHz.

[0006] In 2023, Qiu Jun Deng et al. proposed a single-fed dual-band slotted antenna with a high frequency ratio. This dual-band antenna consists of a rectangular slotted SIW cavity operating in the 40 GHz millimeter-wave band and a ring-shaped slotted SIW cavity operating in the 5.2 GHz microwave band, and is excited by a microstrip line through two independent slots. Due to the self-shielding effect of the SIW cavity, the two radiating elements can be tightly nested, resulting in a compact structure and high utilization of the radiating aperture.

[0007] In summary, existing microwave and millimeter-wave dual-band antennas still have some problems. On the one hand, most antennas lack circular polarization, making it difficult to effectively overcome multipath effects in complex communication environments, resulting in a significant reduction in signal stability and reliability. On the other hand, their narrow operating bandwidth cannot meet the demands of multi-band, high-speed data transmission, and they cannot flexibly adapt to diverse communication services and standards, hindering the development and application of communication technologies. Utility Model Content

[0008] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and provide a microwave and millimeter-wave circularly polarized antenna based on a SIW circular cavity, which can operate simultaneously in microwave and millimeter-wave frequency bands and has circular polarization performance in both frequency bands.

[0009] To achieve the above objectives, the technical solution provided by this utility model is as follows: a microwave and millimeter-wave circularly polarized antenna based on a SIW circular cavity, comprising a first dielectric substrate, a second dielectric substrate, a millimeter-wave radiating patch, a microwave radiating patch, a microwave feed patch, a metal pillar through-hole, a millimeter-wave SIW circular cavity, a metal ground plane, a microwave feed probe, a microwave feed network, and a millimeter-wave feed network; the upper surface of the first dielectric substrate is printed with interconnected millimeter-wave radiating patches, microwave radiating patches, and microwave feed patches; the first dielectric substrate forms multiple millimeter-wave SIW circular cavities through built-in metal pillar through-holes; each millimeter-wave SIW circular cavity is composed of metal pillar through-holes and upper and lower metal layers; the metal pillar through-holes penetrate the first dielectric substrate and the microwave radiating patch; the microwave radiating patch has multiple periodic circular holes, which are formed by the metal through-holes penetrating the microwave radiating patch; the circular area enclosed by the metal pillars of each millimeter-wave SIW circular cavity on the periodic circular holes of the microwave radiating patch serves as the millimeter-wave radiating patch; each millimeter-wave radiating patch... Each millimeter-wave SIW circular cavity within the chip has two parallel radiating slots, through which electromagnetic waves in the millimeter-wave band are radiated. All millimeter-wave radiating patches are arranged in a rotating array with the center of the microwave radiating patch as the center. The microwave feed patch and the microwave radiating patch are connected. The second dielectric substrate is located directly below the first dielectric substrate. The upper surface of the second dielectric substrate is printed with a metal ground plane, on which feed slots and feed circular holes for microwave feed probes are etched. The lower surface of the second dielectric substrate is printed with a microwave feed network and a millimeter-wave feed network. The microwave feed network consists of a 1-to-2 power divider with a 90° phase difference, connected to the microwave feed probe, transmitting the excitation signal to the microwave feed patch, thereby exciting the microwave radiating patch and achieving circular polarization radiation in the microwave band. The millimeter-wave feed network consists of a 1-to-4 ring power divider, coupling the excitation signal from the feed slot to the millimeter-wave SIW circular cavity, thereby exciting the millimeter-wave radiating patch and achieving circular polarization radiation in the millimeter-wave band.

[0010] Furthermore, the millimeter-wave feed network includes a millimeter-wave port and four output terminals. The millimeter-wave port and the four output terminals are connected through a ring power divider, and generate four signals with phase differences of 0°, 90°, 180° and 270° in sequence. Each signal is coupled to the corresponding millimeter-wave SIW circular cavity through the corresponding feed gap to excite the radiation in the millimeter-wave frequency band.

[0011] Furthermore, the microwave feed network includes a microwave port and two output terminals. The microwave port and the two output terminals are connected by a low-pass filter and a 1-to-2 power divider. The low-pass filter splits the excitation signal input from the microwave port into two signals to the two output terminals. One signal travels a length that is one-quarter of the working wavelength longer than the other signal, resulting in a 90° phase difference between the two signals.

[0012] Furthermore, the microwave feeding probe passes sequentially through the second dielectric plate, the metal ground plate, and the first dielectric plate before being electrically connected to the microwave feeding patch.

[0013] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0014] This invention achieves a co-aperture design for both microwave and millimeter-wave frequency bands by reusing the upper metal layer of the entire millimeter-wave SIW circular cavity array as a microwave radiating patch. Circular polarization performance for both microwave and millimeter-wave frequency bands is achieved through orthogonal feeding with a 90° phase difference and sequential rotation technology (i.e., rotating array). In the millimeter-wave frequency band, the TM020 and TM120 modes of the millimeter-wave SIW circular cavity are excited via coupling slots, resulting in dual-frequency characteristics. Sequential rotation technology further expands the impedance bandwidth and axial ratio bandwidth of the millimeter-wave frequency band, with -10 dB impedance bandwidths of 25-33 GHz (27.6%) and 34-39.4 GHz (14.7%), and axial ratio bandwidths of 26.2-33 GHz (23%) and 35.1-39.1 GHz (10.8%), respectively. Attached Figure Description

[0015] Figure 1 This is an exploded view of a microwave / millimeter-wave circularly polarized antenna.

[0016] Figure 2 This is a structural diagram of the upper surface of the first dielectric substrate in a microwave / millimeter-wave circularly polarized antenna.

[0017] Figure 3 This is a structural diagram of the upper surface of the second dielectric substrate in a microwave / millimeter-wave circularly polarized antenna.

[0018] Figure 4 This is a structural diagram of the lower surface of the second dielectric substrate in a microwave / millimeter-wave circularly polarized antenna.

[0019] Figure 5 The figure shows the simulation results of the S-parameters of a microwave / millimeter-wave circularly polarized antenna.

[0020] Figure 6 The figure shows the simulation results of the axial ratio and gain of the microwave millimeter-wave circularly polarized antenna in the microwave band.

[0021] Figure 7 The figure shows the simulation results of the axial ratio and gain of the microwave millimeter-wave circularly polarized antenna in the millimeter-wave band.

[0022] Figure 8 The image shows the simulation results of the radiation pattern of a microwave millimeter-wave circularly polarized antenna in the microwave band at 4.8 GHz.

[0023] Figure 9The image shows the simulation results of the radiation pattern of a microwave millimeter-wave circularly polarized antenna in the millimeter-wave band at 28 GHz.

[0024] Figure 10 The image shows the simulation results of the radiation pattern of a microwave millimeter-wave circularly polarized antenna in the millimeter-wave band at 38 GHz. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0026] like Figures 1 to 4 As shown, this embodiment discloses a microwave millimeter-wave circularly polarized antenna based on a SIW circular cavity, including a first dielectric substrate 11, a second dielectric substrate 12, a millimeter-wave radiating patch 21, a microwave radiating patch 22, a microwave feed patch 3, a metal via 4, a millimeter-wave SIW circular cavity 5, a metal ground plane 6, a microwave feed probe 7, a microwave feed network 81, and a millimeter-wave feed network 82; the upper surface of the first dielectric substrate 11 is printed with interconnected microwave radiating patches 22 and microwave feed patches 3, the first dielectric substrate 11... Multiple millimeter-wave SIW circular cavities 5 are formed through built-in metal through-holes 4. Each millimeter-wave SIW circular cavity 5 consists of metal through-holes 4 and upper and lower metal layers. The metal through-holes 4 penetrate the first dielectric substrate 11 and the microwave radiating patch 22. The microwave radiating patch 22 has multiple periodic circular holes 212, which are formed by the metal through-holes 4 penetrating the microwave radiating patch. The circular area enclosed by the periodic circular holes 212 serves as the millimeter-wave radiating patch 21. Each millimeter-wave radiating patch 21 contains a... Two parallel radiating slots 211 radiate electromagnetic waves in the millimeter-wave band. All millimeter-wave radiating patches 21 are arranged in a rotating array with the center of the microwave radiating patch 22 as the center. The second dielectric substrate 12 is located directly below the first dielectric substrate 11. A metal ground plane 6 is printed on the upper surface of the second dielectric substrate 12. Feed gaps 61 and feed holes 71 for microwave feed probes 7 to pass through are etched on the metal ground plane 6. A microwave feed grid is printed on the lower surface of the second dielectric substrate 12. The microwave feed network 81 consists of a 1-to-2 power divider with a phase difference of 90° and is connected to the microwave feed probe 7. It transmits the excitation signal to the microwave feed patch 3, thereby exciting the microwave radiation patch 22 to achieve circular polarization radiation in the microwave band. The millimeter-wave feed network 82 consists of a 1-to-4 ring power divider, which couples the excitation signal from the feed gap 61 to the millimeter-wave SIW circular cavity 5, thereby exciting the millimeter-wave radiation patch 21 to achieve circular polarization radiation in the millimeter-wave band.

[0027] Specifically, the two radiating slots 221 within the millimeter-wave radiating patch 21 are used to cut surface currents and excite the TM020 and TM120 modes of the millimeter-wave SIW circular cavity 5, thereby enabling the antenna to radiate electromagnetic waves into space and achieving dual-frequency characteristics in the millimeter-wave band, with operating frequencies of 28 GHz and 38 GHz, respectively. Furthermore, since the diameter of the millimeter-wave SIW circular cavity 5 is greater than half the operating wavelength, an interleaved arrangement method is used to reduce the sidelobe level of the millimeter-wave SIW circular cavity 5 array.

[0028] Specifically, the microwave radiating patch 22 is obtained by multiplexing the upper metal layer of the entire millimeter-wave SIW circular cavity 5 array, and its specific shape is square, which is equivalent to a patch antenna for radiation. Microwave feeding patches 3 are placed on two adjacent sides of the microwave radiating patch 22 to transmit an excitation signal with a 90° phase difference to the microwave radiating patch 22, so that the antenna meets the condition of circular polarization radiation in the microwave frequency band.

[0029] Specifically, the metal floor 6 is etched with four feed slots 61 and feed holes 71 for microwave feed probes to pass through. The feed slots 61 are obtained by sequentially rotating one feed slot 61. The four feed slots 61 correspond one-to-one with the four millimeter-wave SIW circular cavities 5.

[0030] Specifically, the microwave feed network 81 is composed of a 1-to-2 power divider with a 90° phase difference. The excitation signal is input from the microwave port 811, passes through a low-pass filter 813 and is then split into two signals. One signal travels a length that is one-quarter of the working wavelength longer than the other signal, resulting in a 90° phase difference between the two signals. Then, the signal passes from the two output terminals 812 through the microwave feed probe 7, sequentially through the second dielectric substrate 12, the metal ground plate 6, and the first dielectric substrate 11 before reaching the microwave feed patch 3. Finally, the microwave feed patch 3 feeds the excitation signal to the microwave radiation patch 22 to achieve radiation in the microwave frequency band.

[0031] Specifically, the millimeter-wave feed network 82 is composed of a one-to-four ring power divider. The excitation signal is input from the millimeter-wave port 821, passes through the ring power divider, and sequentially generates four signals with phase differences of 0°, 90°, 180°, and 270° to the four output terminals 822. Each signal is coupled to the corresponding millimeter-wave SIW circular cavity 5 through the corresponding feed gap 61 to excite the radiation in the millimeter-wave frequency band.

[0032] Specifically, the length and width of the first dielectric substrate 11 and the second dielectric substrate 12 are both 60 mm. The thickness of the first dielectric substrate 11 is 0.787 mm, and the thickness of the second dielectric substrate 12 is 0.254 mm. Both are made of Rogers 5880 material with a dielectric constant of 2.2 and a loss tangent of 0.0009. The length and width of the microwave radiating patch 22 are both 41 mm. The radius of the millimeter-wave SIW circular cavity 5 is 6.48 mm. The length and width of the radiating slot 211 are 9.3 mm and 1.15 mm, respectively. The length and width of the microwave feeding patch 3 are 11.5 mm and 5 mm, respectively.

[0033] like Figure 5 As shown in the figure, the S-parameter simulation results of the microwave millimeter-wave circularly polarized antenna described in this embodiment are presented. It can be seen from the figure that the impedance bandwidths of this invention with a reflection coefficient less than -10dB are 4.61-4.86 GHz (5.3%), 25-33 GHz (27.6%), and 34-39.4 GHz (14.7%).

[0034] like Figure 6 As shown, the simulation results of the axial ratio and gain of the microwave millimeter-wave circularly polarized antenna described in this embodiment in the microwave band are presented. It can be seen from the figure that when this invention operates in the microwave band, the 3dB axial ratio bandwidth is 4.78-4.89GHz (2.3%), and the peak gain is 5.26 dBic.

[0035] like Figure 7 As shown, the simulation results of the axial ratio and gain of the microwave millimeter-wave circularly polarized antenna described in this embodiment in the millimeter-wave band are presented. It can be seen from the figure that when this invention operates in the millimeter-wave band, the 3dB axial ratio bandwidths are 26.2-33 GHz (23%) and 35.1-39.1 GHz (10.8%), and the peak gains are 10.68 dBic and 11.67 dBic, respectively.

[0036] like Figures 8 to 10 The figure shows the simulation results of the radiation patterns of the microwave and millimeter-wave circularly polarized antenna described in this embodiment at 4.8 GHz in the microwave band and 28 GHz and 38 GHz in the millimeter-wave band. It can be seen from the figure that, in the +z axis direction, the left-hand circularly polarized field in the microwave band is more than 20 dB higher than the right-hand circularly polarized field, and the right-hand circularly polarized field in the millimeter-wave band is more than 20 dB higher than the left-hand circularly polarized field. This indicates that this invention is a left-hand circularly polarized antenna in the microwave band and a right-hand circularly polarized antenna in the millimeter-wave band.

[0037] The embodiments described above are merely preferred embodiments of this utility model and are not intended to limit the scope of implementation of this utility model. Therefore, all changes made in accordance with the shape and principle of this utility model should be covered within the protection scope of this utility model.

Claims

1. A microwave millimeter wave circularly polarized antenna based on SIW circular cavity, characterized in that: The system includes a first dielectric substrate (11), a second dielectric substrate (12), a millimeter-wave radiating patch (21), a microwave radiating patch (22), a microwave feed patch (3), a metal via (4), a millimeter-wave SIW circular cavity (5), a metal ground plane (6), a microwave feed probe (7), a microwave feed network (81), and a millimeter-wave feed network (82). The upper surface of the first dielectric substrate (11) is printed with interconnected microwave radiating patches (22) and microwave feed patches (3). The first dielectric substrate (11) forms multiple millimeter-wave SIWs through built-in metal vias (4). The W circular cavity (5) is composed of a metal through-hole (4) and upper and lower metal layers. The metal through-hole (4) penetrates the first dielectric substrate (11) and the microwave radiation patch (22). The microwave radiation patch (22) has multiple periodic circular holes (212). The periodic circular holes (212) are formed by the metal through-hole (4) penetrating the microwave radiation patch (22). The circular area enclosed by the periodic circular holes (212) serves as the millimeter-wave radiation patch (21). Each millimeter-wave radiation patch (21) has two parallel radiating channels. The radiating slot (211) radiates electromagnetic waves in the millimeter-wave band. All millimeter-wave radiating patches (21) are arranged in a rotating array with the center of the microwave radiating patch (22) as the center. The second dielectric plate (12) is located directly below the first dielectric plate (11). The upper surface of the second dielectric plate (12) is printed with a metal ground plate (6). The metal ground plate (6) is etched with a feed gap (61) and a feed hole (71) for the microwave feed probe (7) to pass through. The lower surface of the second dielectric plate (12) is printed with a microwave feed network. (81) and millimeter-wave feed network (82); the microwave feed network (81) is composed of a 1-to-2 power divider with a phase difference of 90° and is connected to the microwave feed probe (7) to transmit the excitation signal to the microwave feed patch (3), thereby exciting the microwave radiation patch (22) to achieve circular polarization radiation in the microwave band; the millimeter-wave feed network (82) is composed of a 1-to-4 ring power divider to couple the excitation signal from the feed gap (61) to the millimeter-wave SIW circular cavity (5), thereby exciting the millimeter-wave radiation patch (21) to achieve circular polarization radiation in the millimeter-wave band.

2. The circularly polarized microwave / millimeter wave antenna based on SIW circular cavity according to claim 1, characterized in that: The millimeter-wave feed network (82) includes a millimeter-wave port (821) and four output terminals (822). The millimeter-wave port (821) and the four output terminals (822) are connected through a ring power divider, and generate four signals with phase differences of 0°, 90°, 180° and 270° in sequence. Each signal is coupled to the corresponding millimeter-wave SIW circular cavity (5) through the corresponding feed gap (61) to excite the radiation of the millimeter-wave frequency band.

3. The circularly polarized microwave / millimeter wave antenna based on SIW circular cavity according to claim 1, characterized in that: The microwave feed network (81) includes a microwave port (811) and two output terminals (812). The microwave port (811) and the two output terminals (812) are connected by a low-pass filter (813) and a 1-to-2 power divider. The low-pass filter (813) splits the excitation signal input from the microwave port (811) into two signals to the two output terminals (812). One of the signals travels a length that is one-quarter of the working wavelength longer than the other, so that the two signals have a 90° phase difference.

4. The circularly polarized microwave / millimeter wave antenna based on SIW circular cavity according to claim 1, characterized in that: The microwave feed probe (7) passes through the second dielectric plate (12), the metal ground plate (6), and the first dielectric plate (11) in sequence and is then electrically connected to the microwave feed patch (3).

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