A SIW Self-Multiplexing Slot Antenna with Circularly Polarized Radiation

Abstract

The present invention discloses a SIW self-duplexing slot antenna with circular polarization radiation, which includes a first metal layer, a first dielectric layer, and a second metal layer arranged in sequence from bottom to top. Among them, a plurality of first through-holes and three second through-holes are provided on the first dielectric layer. The plurality of first through-holes are arranged along the circumference, and the plurality of first through-holes form three spaced input windows on the circumference and form a SIW resonant cavity inside the circumference; the three second through-holes are located inside the circumference formed by the plurality of first through-holes; the second metal layer includes a metal main body portion and a slot opened on the metal main body portion, and a square microstrip patch is nested in the slot. A first microstrip line, a second microstrip line, and a third microstrip line extending outward are spacedly arranged on the outer periphery of the metal main body portion. The antenna of the present invention realizes a tunable self-duplexing antenna with good inter-port isolation on the basis of miniaturization, and has the characteristics of compact structure, excellent radiation performance, and wide application range.

Description

Technical Field

[0001] The present invention belongs to the technical field of antennas, and particularly relates to a SIW self-duplexing slot antenna with circularly polarized radiation. Background Art

[0002] In recent years, multi-band antennas have been widely used in handheld and mobile wireless communication devices. Due to their inherent characteristics, multi-band antennas eliminate the need for multiple antennas in multiple application scenarios and effectively improve the portability of wireless communication systems. It should be noted that multi-band antennas usually work with a certain number of transceivers in different frequency bands, thus facing problems of poor isolation and high interference. Therefore, a frequency selection circuit such as a duplexer (multi-channel synthesizer) needs to be introduced as a bridge between the multi-band antenna and the transceiver to improve the isolation and anti-interference ability between the receiving and transmitting channels. The presence of the duplexer inevitably increases the complexity of the entire circuit and limits its application in high-density integration, and the emergence of self-duplexing antennas has become an effective way to solve this problem.

[0003] Substrate integrated waveguide (SIW) has been widely used in radio frequency front-end components due to its high Q value and applicability to work with planar structures. In combination with slot antennas, the SIW cavity exhibits good ability to suppress surface waves and confine energy, which can effectively improve the radiation efficiency, gain and front-to-back ratio of the antenna, and thus provide relatively ideal radiation characteristics.

[0004] The prior art (A. Kumar and S. Raghavan, "A Self-Triplexing SIW Cavity-Backed Slot Antenna," in IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 5, pp. 772-775, May 2018, doi: 10.1109 / LAWP.2018.2815665.) reported a self-duplexing antenna based on SIW technology for multi-band communication systems. The proposed antenna uses a T-shaped slot inserted at the top of the SIW cavity to divide the cavity into three independent resonators excited by discrete microstrip lines, which work in three frequency bands of 6.53, 7.65 and 9.09 GHz respectively. By appropriately optimizing the antenna parameters, an isolation of better than 19 dB is achieved between any two input ports. The peak gains generated by the proposed self-duplexing antenna at the resonant frequencies are 3.1, 4.7 and 3.9 dBi respectively, accompanied by stable radiation patterns.

[0005] In the prior art, the nested structure between SIW cavities requires a matching excitation device composed of a microstrip line and a coaxial probe, which increases the design difficulty and the occupied area of the feeding network, and is not conducive to the miniaturization of the antenna module.

[0006] In addition, some self-duplex antennas based on modified slots in the metal layer on the upper surface of the SIW cavity are also provided in the related art. By correcting the geometric structure of the slots, the SIW cavity is divided into multiple independently operating resonators, achieving good radiation in the corresponding frequency bands and generating satisfactory isolation between ports. However, so far, the discussion about self-duplex antennas generally focuses on fixed slot structures, ignoring the multiple application scenarios brought by their tuning characteristics. Summary of the Invention

[0007] In order to solve the above problems existing in the prior art, the present invention provides a SIW self-duplex slot antenna with circular polarization radiation. The technical problems to be solved by the present invention are achieved through the following technical solutions:

[0008] The present invention provides a SIW self-duplex slot antenna with circular polarization radiation, including a first metal layer, a first dielectric layer, and a second metal layer arranged in sequence from bottom to top. Among them,

[0009] A plurality of first through-holes and three second through-holes are provided on the first dielectric layer. The plurality of first through-holes are arranged along the circumference. The plurality of first through-holes form three spaced input windows on the circumference and form a SIW resonator inside the circumference. The three second through-holes are located inside the circumference formed by the plurality of first through-holes. Metal materials are filled in both the first through-holes and the second through-holes.

[0010] The second metal layer includes a metal main body and a slot opened on the metal main body. A square microstrip patch is nested in the slot. A first microstrip line, a second microstrip line, and a third microstrip line extending outward are spaced on the outer periphery of the metal main body. The projection of the slot is located inside the SIW resonator. The projections of the first microstrip line, the second microstrip line, and the third microstrip line respectively overlap with the three input windows.

[0011] In an embodiment of the present invention, a plurality of third through-holes are opened in the first metal layer. The plurality of third through-holes form a first circular region. The size and arrangement mode of the plurality of third through-holes are the same as those of the plurality of first through-holes.

[0012] In an embodiment of the present invention, a plurality of fourth through-holes are further opened in the second metal layer. The fourth through-holes form a second circular region. The size and arrangement mode of the fourth through-holes are the same as those of the plurality of first through-holes.

[0013] In one embodiment of the present invention, the slot includes a square annular slot and strip-shaped slots provided at three corners of the square annular slot, and the square microstrip patch is disposed inside the square annular slot.

[0014] In one embodiment of the present invention, the outer side wall of the square annular slot close to the first microstrip line bulges outwards to form a rectangular slot convex portion; the outer side wall of the square annular slot close to the third microstrip line caves inwards to form a rectangular slot concave portion.

[0015] In one embodiment of the present invention, the length of the slot convex portion is 4 mm and the width is 0.55 mm; the length of the slot concave portion is 4 mm and the width is 0.55 mm.

[0016] In one embodiment of the present invention, the distance between the side of the slot convex portion close to the square microstrip patch and the square microstrip patch is equal to the distance between the side of the slot concave portion close to the square microstrip patch and the square microstrip patch.

[0017] In one embodiment of the present invention, the first microstrip line, the second microstrip line, and the third microstrip line respectively extend axially inwards from the outside of the metal main body portion to the inside of the metal main body portion, and there are gaps between both sides of the first microstrip line, the second microstrip line, and the third microstrip line and the metal main body portion.

[0018] In one embodiment of the present invention, the widths of the first microstrip line, the second microstrip line, and the third microstrip line are all 1.5 mm.

[0019] In one embodiment of the present invention, the length of the first microstrip line extending into the metal main body portion is 2.5 mm, the length of the second microstrip line extending into the metal main body portion is 3.4 mm, and the length of the third microstrip line extending into the metal main body portion is 3.2 mm.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The SIW self-duplex slot antenna with circular polarization radiation of the present invention combines a T-shaped slot and a square annular slot etched on the top of the SIW cavity to achieve cavity segmentation and obtain a cavity resonator with a certain anti-interference ability. The separate microstrip patch in the middle greatly reduces the coupling between ports, contributing to obtaining an isolation of more than 31 dB. The improved slots allow the operating frequencies of each port to be adjusted separately to provide different frequency ratios, while the other ports are not affected. In order to illustrate the tuning effect of introducing perturbation elements in the slots, the two vertical ports of the self-duplex antenna are adjusted to the same resonance frequency to generate circular polarization radiation. Therefore, the antenna proposed by the present invention realizes a tunable self-duplex antenna with good port isolation on the basis of miniaturization, and has the characteristics of compact structure, excellent radiation performance and wide application range, indicating the practical significance of the tunability of the self-duplex antenna for broadening the application scenarios of the antenna.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0023] Figure 1 is a schematic structural diagram of a SIW self-duplex slot antenna with circular polarization radiation provided by an embodiment of the present invention;

[0024] Figure 2 is a schematic structural diagram of a first metal layer provided by an embodiment of the present invention;

[0025] Figure 3 is a schematic structural diagram of a first dielectric layer provided by an embodiment of the present invention;

[0026] Figure 4 is a schematic structural diagram of a second metal layer provided by an embodiment of the present invention;

[0027] Figure 5 is a schematic simulation structural diagram provided by an embodiment of the present invention.

[0028] Description of the Reference Numerals:

[0029] 1 - First metal layer; 101 - Third through hole; 102 - First circular area; 103 - Fifth through hole; 2 - First dielectric layer; 201 - First through hole; 202 - Second through hole; 203 - Input window; 204 - SIW resonator; 3 - Second metal layer; 301 - Metal main body; 302 - Slot; 3021 - Square annular slot; 3022 - Strip-shaped slot; 3023 - Slot convex part; 3024 - Slot concave part; 303 - Square microstrip patch; 304 - First microstrip line; 305 - Second microstrip line; 306 - Third microstrip line; 307 - Fourth through hole; 308 - Second circular area; 309 - Sixth through hole. Detailed Embodiment

[0030] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following provides a detailed description of a SIW self-duplexing slot antenna with circular polarization radiation proposed according to the present invention in combination with the accompanying drawings and specific embodiments.

[0031] The foregoing and other technical contents, features, and effects of the present invention can be clearly presented in the following detailed description in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and specific understanding of the technical means and effects adopted by the present invention to achieve the intended purpose can be obtained. However, the accompanying drawings are only for reference and illustration, and are not used to limit the technical solution of the present invention.

[0032] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant is intended to cover non-exclusive inclusion, so that an article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of another identical element in the article or device including the said element.

[0033] An embodiment of the present invention provides a SIW self-duplexing slot antenna with circular polarization radiation. Please refer to Figures 1 to 4 simultaneously. The SIW self-duplexing slot antenna includes a first metal layer 1, a first dielectric layer 2, and a second metal layer 3 arranged in sequence from bottom to top. A plurality of first through holes 201 and three second through holes 202 are provided on the first dielectric layer 2. The plurality of first through holes 201 are arranged along the circumference. The plurality of first through holes 201 form three spaced input windows 203 on the circumference and form a SIW resonance cavity 204 inside the circumference. The three second through holes 202 are located inside the circumference formed by the plurality of first through holes 201. The first through holes 201 and the second through holes 202 are both filled with a metal material.

[0034] It should be noted that except for the positions of the three input windows 203, the central angles between other first through holes 201 are equal. The three second through holes 202 are respectively located near each input window 203 to assist in impedance matching and at the same time affect the corresponding electric field distribution to better separate the excitation frequencies.

[0035] The second metal layer 3 includes a metal main body 301 and a slit 302 formed in the metal main body 301. A square microstrip patch 303 is nested in the slit 302. On the outer periphery of the metal main body 301, a first microstrip line 304, a second microstrip line 305, and a third microstrip line 306 extending outward are arranged at intervals. The projection of the slit 302 is located inside the SIW resonator 204; the projections of the first microstrip line 304, the second microstrip line 305, and the third microstrip line 306 respectively overlap with the three input windows 203, so that the first microstrip line 304, the second microstrip line 305, and the third microstrip line 306 form three input ports with the three input windows 203.

[0036] Optionally, as Figure 2 shown, a plurality of third through-holes 101 are formed in the first metal layer 1. The plurality of third through-holes 101 form a first circular region 102. The sizes and arrangement manners of the plurality of third through-holes 101 are the same as those of the plurality of first through-holes 201. That is to say, the position of each third through-hole 101 corresponds to the position of the first through-hole 201 on the first dielectric layer 2 one by one. Three fifth through-holes 103 are further arranged in the first circular region 102 formed by the third through-holes 101. The positions of the three fifth through-holes 103 correspond to the positions of the three second through-holes 202 one by one in the vertical direction.

[0037] Optionally, as Figure 4 shown, a plurality of fourth through-holes 307 are further formed in the second metal layer 3. The fourth through-holes 307 form a second circular region 308. The sizes and arrangement manners of the fourth through-holes 307 are the same as those of the plurality of first through-holes 201. That is to say, the position of each fourth through-hole 307 corresponds to the position of the first through-hole 201 on the first dielectric layer 2 one by one. Three sixth through-holes 309 are arranged inside the second circular region 308 formed by the fourth through-holes 307. The positions of the three sixth through-holes 309 correspond to the positions of the three second through-holes 202 one by one in the vertical direction.

[0038] Furthermore, the slit 302 includes a square annular slit 3021 and strip-shaped slits 3022 arranged at three corners of the square annular slit 3021. The square microstrip patch 303 is arranged inside the square annular slit 3021. The outer side wall of the square annular slit 3021 close to the first microstrip line 304 bulges outward to form a rectangular slit convex part 3023; the outer side wall of the square annular slit 3021 close to the third microstrip line 306 concaves inward to form a rectangular slit concave part 3024, so that the operating frequencies of two perpendicular input ports (corresponding to the second microstrip line 305 and the third microstrip line 306) overlap, which is beneficial to the generation of circular polarization radiation; at the same time, the distance from the operating frequency of another input port (corresponding to the first microstrip line 304) is increased to improve the isolation degree.

[0039] Of course, in some other embodiments of the present invention, the correction of the slot 302 can be carried out in different ways, such as extending both sides of the slot 302 outward or inwardly recessing at the same time, etc. This embodiment does not limit this. It should be understood that the slot 302 divides the SIW resonator cavity into three independently operating resonators by using its own geometric structure, and at the same time realizes the miniaturization of the self-duplexing slot antenna by means of the loading effect.

[0040] Furthermore, the distance between the side of the slot convex portion 3023 close to the square microstrip patch 303 and the square microstrip patch 303 is equal to the distance between the side of the slot concave portion 3024 close to the square microstrip patch 303 and the square microstrip patch 303. In this embodiment, the square microstrip patch 303 is translated 0.275 mm to the left from the center position of the second circular region 308.

[0041] Such as Figure 4 As shown, the first microstrip line 304, the second microstrip line 305, and the third microstrip line 306 respectively extend axially inward from the outside of the metal main body 301 to the inside of the metal main body 301, and there are gaps between both sides of the first microstrip line 304, the second microstrip line 305, and the third microstrip line 306 and the metal main body 301. The widths of the first microstrip line 304, the second microstrip line 305, and the third microstrip line 306 are all 1.5 mm.

[0042] Furthermore, the lengths of the first microstrip line 304, the second microstrip line 305, and the third microstrip line 306 extending into the SIW resonator 204 respectively determine the coupling strength between the excitation source and the SIW resonator 204. Preferably, the length of the first microstrip line 304 extending into the metal main body 301 is 2.5 mm, the length of the second microstrip line 305 extending into the metal main body 301 is 3.4 mm, and the length of the third microstrip line 306 extending into the metal main body 301 is 3.2 mm.

[0043] In addition, it should be noted that in the above SIW self-duplexing slot antenna, the sizes of the first metal layer 1, the first dielectric layer 2, and the second metal layer 3 are actually the same, and the boundaries of each layer coincide.

[0044] It can be understood that the tuning effect of the slot 302 is determined by the shape and position of the slot 302. Such as Figure 4 As shown, in this embodiment, the left side of the slot 302 extends outward a rectangle with a length of 4 mm in the first direction x and a width of 0.55 mm in the second direction y; the right side of the slot 302 is recessed inward a rectangle with a length of 4 mm in the first direction x and a width of 0.55 mm in the second direction y. In other words, the length of the slot convex portion 3023 is 4 mm and the width is 0.55 mm; the length of the slot concave portion 3024 is 4 mm and the width is 0.55 mm.

[0045] It should be noted that there are alternative solutions for the shapes and introduction positions of the above-mentioned perturbation elements (including the slit convex part 3023 and the slit concave part 3024), which can correspond to different frequency ratio targets. Based on the combination of the T-shaped slit and the square annular slit, extending a rectangle from the side of the slit or outward, or inwardly recessing a rectangle, or remaining unchanged, and the changes in the length in the first direction x and the width in the second direction y of the rectangle all fall within the protection scope of the present invention.

[0046] In addition, the geometric shape of the slit 302 in the second metal layer 3 should be flexibly adjusted according to the number of ports. For example, when the second metal layer 3 only includes the first microstrip line 304 and the second microstrip line 305, the slit 302 needs to divide the SIW resonator 204 into two parts accordingly, and the first microstrip line 304 and the second microstrip line 305 are respectively fed.

[0047] It can be understood that the radiation frequency of this SIW multiplexing slot antenna is a comprehensive result closely related to the size of the SIW cavity 204, the position and shape of the slit 302, and the number and position of the second through holes 202.

[0048] Exemplarily, the radius of the SIW resonator 204 is 9.8 mm, and the degenerate dual mode TM 110 is used as the working mode. The first dielectric layer 2 uses duroid 5880 Rogers material with a dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 0.508 mm. The diameter of the first through hole 201 is 1 mm, and the central angle between two adjacent first through holes 201 is 7.5 degrees. In this embodiment, the side length of the square microstrip patch 303 is 5 mm.

[0049] Furthermore, the three-dimensional electromagnetic full-wave simulation software HFSS_2022 is used to perform three-dimensional modeling on the above-mentioned SIW multiplexing slot antenna, and the S-parameter, gain, and axial ratio results of the simulation model are as Figure 5 shown.

[0050] From Figure 5 it can be seen that in this simulation, a peak gain of 6.5 dBi is obtained at the resonant frequency of 13 GHz. At the same time, due to the perpendicular position relationship between the two ports, there is an axial ratio distribution of less than 3 dB, generating circularly polarized radiation; a peak gain of 5.66 dBi is obtained at the resonant frequency of 14.61 GHz; the isolation between ports is better than 31 dB.

[0051] During actual use, the gap 302 in the second metal layer 3 divides the SIW resonator 204 into three independently operating resonators, which are fed by the first microstrip line 304, the second microstrip line 305, and the third microstrip line 306 respectively, and radiate outward along the part of the gap corresponding to the port. Among them, the left side of the gap 302 extends outward to form a rectangle with a length of 4 mm in the first direction x and a width of 0.55 mm in the second direction y, and the right side is recessed inward to form a rectangle with a length of 4 mm in the first direction x and a width of 0.55 mm in the second direction y. The introduction of the above perturbation elements adjusts the mutually perpendicular second microstrip line 305 and third microstrip line 306 to the same excitation frequency, generating a self-duplex antenna with circularly polarized radiation.

[0052] The SIW self-duplex slot antenna with circularly polarized radiation in the embodiment of the present invention combines an etched T-shaped slot and a square annular slot on the top of the SIW cavity to achieve cavity segmentation and obtain a cavity resonator with a certain anti-interference ability. The separate microstrip patch in the middle greatly reduces the coupling between ports, helping to obtain an isolation of more than 31 dB. The improved slot allows the operating frequency of each port to be adjusted separately to provide different frequency ratios, while the other ports are not affected. In order to illustrate the tuning effect of introducing perturbation elements in the slot, the present invention adjusts the two vertical ports of the self-duplex antenna to the same resonant frequency to generate circularly polarized radiation. Therefore, the antenna proposed by the present invention realizes a tunable self-duplex antenna with good isolation between ports on the basis of miniaturization, and has the characteristics of compact structure, excellent radiation performance, and wide application range, demonstrating the practical significance of the tunability of the self-duplex antenna for broadening the application scenarios of the antenna.

[0053] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A SIW self-multiplexing slot antenna with circularly polarized radiation, characterized in that, it includes a first metal layer (1), a first dielectric layer (2) and a second metal layer (3) arranged in sequence from bottom to top, wherein, a plurality of first through holes (201) and three second through holes (202) are provided on the first dielectric layer (2), the plurality of first through holes (201) are arranged along the circumference, the plurality of first through holes (201) form three spaced input windows (203) on the circumference and form a SIW resonant cavity (204) inside the circumference; the three second through holes (202) are located inside the circumference formed by the plurality of first through holes (201), and the first through holes (201) and the second through holes (202) are both filled with metal materials; the second metal layer (3) includes a metal main body part (301) and a slot (302) formed on the metal main body part (301), a square microstrip patch (303) is nested in the slot (302), and a first microstrip line (304), a second microstrip line (305) and a third microstrip line (306) extending outward are arranged at intervals on the outer periphery of the metal main body part (301), and the projection of the slot (302) is located inside the SIW resonant cavity (204); the projections of the first microstrip line (304), the second microstrip line (305) and the third microstrip line (306) respectively overlap with the three input windows (203); the slot (302) includes a square annular slot (3021) and strip-shaped slots (3022) arranged at three corners of the square annular slot (3021), and the square microstrip patch (303) is arranged inside the square annular slot (3021); the outer side wall of the square annular slot (3021) close to the first microstrip line (304) bulges outward to form a rectangular slot convex part (3023); the outer side wall of the square annular slot (3021) close to the third microstrip line (306) concaves inward to form a rectangular slot concave part (3024).

2. The SIW self-multiplexing slot antenna with circularly polarized radiation according to claim 1, characterized in that, a plurality of third through holes (101) are formed in the first metal layer (1), the plurality of third through holes (101) form a first circular area (102), and the size and arrangement mode of the plurality of third through holes (101) are the same as the size and arrangement mode of the plurality of first through holes (201).

3. The SIW self-multiplexing slot antenna with circularly polarized radiation according to claim 1, characterized in that, a plurality of fourth through holes (307) are further formed in the second metal layer (3), the fourth through holes (307) form a second circular area (308), and the size and arrangement mode of the fourth through holes (307) are the same as the size and arrangement mode of the plurality of first through holes (201).

4. The SIW self-multiplexing slot antenna with circularly polarized radiation according to claim 1, characterized in that, The length of the slit convex part (3023) is 4 mm, and the width is 0.55 mm; the length of the slit concave part (3024) is 4 mm, and the width is 0.55 mm.

5. The SIW self-multiplexing slot antenna with circularly polarized radiation according to claim 1, characterized in that the distance between the side of the slit convex part (3023) close to the square microstrip patch (303) and the square microstrip patch (303) is equal to the distance between the side of the slit concave part (3024) close to the square microstrip patch (303) and the square microstrip patch (303).

6. The SIW self-multiplexing slot antenna with circularly polarized radiation according to claim 1, characterized in that the first microstrip line (304), the second microstrip line (305) and the third microstrip line (306) respectively extend axially inward from the outside of the metal main body part (301) into the metal main body part (301), and there are gaps between both sides of the first microstrip line (304), the second microstrip line (305) and the third microstrip line (306) and the metal main body part (301).

7. The SIW self-multiplexing slot antenna with circularly polarized radiation according to claim 1, characterized in that the widths of the first microstrip line (304), the second microstrip line (305) and the third microstrip line (306) are all 1.5 mm.

8. The SIW self-multiplexing slot antenna with circularly polarized radiation according to claim 1, characterized in that the length of the first microstrip line (304) extending into the metal main body part (301) is 2.5 mm, the length of the second microstrip line (305) extending into the metal main body part (301) is 3.4 mm, and the length of the third microstrip line (306) extending into the metal main body part (301) is 3.2 mm.

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