Circularly polarized filter grid slot patch antenna based on substrate integrated gap waveguide

Abstract

The application discloses a circularly polarized filtering grid slot patch antenna based on a substrate integrated gap waveguide. The antenna adopts a multilayer stacking structure, and comprises first to fourth dielectric substrates and adhesive layers arranged therebetween from top to bottom. The upper surface of the first dielectric substrate is provided with four cut-corner square patches, and the lower surface of the first dielectric substrate is provided with two cut-corner rectangular patches. The upper surface of the second dielectric substrate is provided with one cross strip and four parasitic strips, and the lower surface of the second dielectric substrate is provided with one circular ring. The upper surface of the third dielectric substrate is provided with a rectangular metal patch with a gap, and the lower surface of the third dielectric substrate is provided with a bifurcated microstrip feed structure and two folded strips. The upper surface of the fourth dielectric substrate is a circular metal patch array, and the lower surface of the fourth dielectric substrate is a rectangular metal patch with the same size as the fourth dielectric. The upper surface and the lower surface of the fourth dielectric substrate are connected through metal columns and jointly form an electromagnetic bandgap structure. The application has excellent upper stopband suppression capability.

Description

Technical Field

[0001] This invention relates to the field of radio frequency and microwave technology, and in particular to a circularly polarized filter grid slotted patch antenna based on a substrate integrated gap waveguide. Background Technology

[0002] With the rapid development of fifth-generation (5G) mobile communication, the millimeter-wave (MMW) band has become a key spectrum resource for achieving high data rates, large system capacity, and efficient spectrum utilization. However, millimeter-wave radio frequency (RF) front-ends face significant challenges in practical applications, including high transmission loss, compact size requirements, and stringent out-of-band rejection requirements. In traditional designs, antennas are typically cascaded with external filters to achieve both radiation and frequency selectivity. This approach inevitably introduces additional insertion loss and increases the overall system size. To overcome these limitations, the design concept of filtered antennas has been proposed and extensively studied, effectively integrating radiation and filtering functions within a single component. Furthermore, antenna polarization significantly impacts its performance. Circularly polarized antennas possess inherent robustness against multi-effects, polarization rotation, and polarization mismatch, enabling stable link performance in complex propagation environments. Compared to linearly polarized filtered antennas, circularly polarized filtered antennas not only maintain high frequency selectivity but also significantly enhance communication reliability and system stability. Therefore, they have attracted increasing research interest in millimeter-wave applications.

[0003] Filtered antenna design methods can generally be divided into two categories. The first category is the synthesis method, derived from filter synthesis theory, in which the antenna element simultaneously acts as a radiator and a terminal resonator of the filter. Undoubtedly, these filtered antennas achieve excellent out-of-band rejection; however, integrating multiple resonators into the feed network inevitably introduces additional insertion loss. To address this issue, an alternative design method for filtered antennas, called the fusion method, has been proposed. According to this method, filtered antennas can be implemented by integrating specific structures within the antenna element, such as stepped impedance resonators, short-circuit pins, and parasitic bands. Since these designs do not require additional filtering circuitry, they have a more compact size compared to filtered antennas based on the synthesis method. Nevertheless, these designs mostly operate in the sub-6 GHz band and only support linearly polarized radiation. To further address the aforementioned issues, several millimeter-wave circularly polarized filtered antennas have been proposed. While satisfactory filtering performance can be achieved, their impedance bandwidth (IBW) or axial ratio bandwidth (ARBW) is typically narrow, making it difficult to fully cover the entire 5 GHz MMW band (24.25–29.5 GHz). Clearly, designing a circularly polarized filter antenna based on a fusion approach while simultaneously achieving wide IBW and wide ARBW still presents significant technical challenges. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, the first objective of this invention is to propose a slotted patch antenna with a circularly polarized filter grid based on a substrate-integrated gap waveguide. By aligning the resonant frequencies of the radiating patch, coupling slots, and feed network, a third-order bandpass filter is formed, exhibiting excellent upper stopband suppression capability. This invention integrates filtering and circularly polarized radiation functions, simultaneously achieving wide impedance bandwidth, wide axial ratio bandwidth, high out-of-band suppression, and compact physical size in the millimeter-wave band, making it suitable for millimeter-wave communication systems such as 5G.

[0005] To achieve the above objectives, a first aspect of the present invention provides a circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide, comprising: a first dielectric substrate, a first adhesive layer, a second dielectric substrate, a second adhesive layer, a third dielectric substrate, a third adhesive layer, and a fourth dielectric substrate stacked sequentially from top to bottom, wherein: Four chamfered square patches are provided at the center of the upper surface of the first dielectric substrate, and the four chamfered square patches are arranged in a 2×2 array. Two chamfered rectangular patches are provided at the center of the lower surface of the first dielectric substrate, and the two chamfered rectangular patches are symmetrically arranged in a clockwise direction at 45 degrees. The upper surface of the second dielectric substrate has a cross strip at the center position, and four parasitic strips surround the cross strip. The four parasitic strips are of equal length and are equidistant from the center position. A circular ring is provided at the center of the lower surface of the second dielectric substrate; The upper surface of the third dielectric substrate is provided with a metal ground structure, which is a rectangular metal patch of the same size as the third dielectric substrate and has an I-shaped rectangular slit etched in the center. The lower surface of the third dielectric substrate is provided with a feeding structure, which is a bifurcated microstrip feeding structure, and the bifurcation of the feeding structure is perpendicular to the rectangular gap. The lower surface of the third dielectric substrate is provided with two folded strips, which are located on both sides of the feeding structure. The fourth dielectric substrate is an electromagnetic bandgap structure, which is a periodically arranged mushroom-shaped structural unit. The feeding structure of the third dielectric substrate and the fourth dielectric substrate together constitute the SIGW feeding network. The first dielectric substrate and the second dielectric substrate are connected by a first adhesive layer; The second dielectric substrate and the third dielectric substrate are connected by a second adhesive layer; The third dielectric substrate and the fourth dielectric substrate are connected by a third adhesive layer.

[0006] According to one embodiment of the present invention, four chamfered square patches are centrally symmetrical about the geometric center point of the upper surface of the first dielectric substrate, the chamfered angles of the four chamfered square patches are the same, and the spacing between each pair of the four chamfered square patches is the same; the shape of the chamfered square patches is a square with two opposite corners cut off by a first isosceles right triangle, and the right-angled side of the first isosceles right triangle is less than or equal to half the side length of the square.

[0007] According to one embodiment of the present invention, two chamfered rectangular patches are centrally symmetrical about the geometric center point of the lower surface of the first dielectric substrate, the chamfered angles of the two chamfered rectangular patches are the same, and the two chamfered rectangular patches are centrally symmetrical about the geometric center point at 45 degrees; the shape of the chamfered rectangular patches is that a second isosceles right triangle is cut off from the four right angles of the rectangle, and the right-angled side of the second isosceles right triangle is equal to half the short side of the rectangle.

[0008] According to one embodiment of the present invention, the cross strips are centrally symmetrical about the geometric center point of the upper surface of the second dielectric substrate, and the four parasitic strips are located outside the four opening directions of the cross strips, and the four parasitic strips are equidistant from the geometric center point of the upper surface of the second dielectric substrate.

[0009] According to one embodiment of the present invention, a circular ring is etched on the lower surface of the second dielectric substrate, and the center of the circular ring is the geometric center of the lower surface of the second dielectric substrate.

[0010] According to one embodiment of the present invention, the I-shaped rectangular gaps are laterally distributed at the center of the metal ground structure and are centrally symmetrical about the geometric center point of the metal ground structure.

[0011] According to one embodiment of the present invention, the feeding structure includes a first microstrip line, a first transition structure, a second transition structure, and two second microstrip lines connected in sequence; wherein, The first microstrip line is longitudinally distributed at the geometric center point on the lower surface of the third dielectric substrate. One end of the first microstrip line is connected to the center position of the first transition structure. The first transition structure is connected to the center position of the second transition structure. The two second microstrip lines are respectively connected to the two ends of the second transition structure, and the two second microstrip lines are perpendicular to the rectangular gap.

[0012] According to one embodiment of the present invention, the two folded strips are in the form of a square waveform, distributed on both sides of the power supply structure, and are symmetrical about the line of symmetry of the power supply structure.

[0013] According to one embodiment of the present invention, the upper surface of the mushroom-shaped structural unit is a plurality of circular patches arranged in an array, and the lower surface of the mushroom-shaped structural unit is a rectangular metal patch of the same size as the fourth dielectric substrate. The plurality of circular patches and the rectangular metal patch of the mushroom-shaped structural unit are connected by metal pillars.

[0014] According to one embodiment of the present invention, the materials of the chamfered square patch, chamfered rectangular patch, cross strip, parasitic strip, circular ring, metal ground, power supply structure, folded strip, and electromagnetic bandgap structure are all copper, silver, or gold, the same as those used in printed circuits.

[0015] Compared with the prior art, the present invention has the following technical effects: This invention proposes a circularly polarized filtered grid slotted patch antenna suitable for millimeter-wave (MMW) applications. The antenna element mainly consists of a two-layer patch structure, a coupling slot, and a substrate integrated gap waveguide (SIGW) feed network. Circular polarization radiation is achieved using a chamfered patch antenna, exhibiting the lowest axial ratio within the operating bandwidth. To further widen the axial ratio bandwidth (ARBW), a cross stub strip and four parasitic strips are introduced to generate another minimum axial ratio. Notably, the radiating element, coupling slot, and feed network together constitute a third-order filter, significantly improving upper stopband suppression. Furthermore, by adding a circular ring and two folded strips to the antenna element, two controllable radiation nulls are generated in the lower stopband, achieving... The antenna exhibits a 10 dB impedance bandwidth (IBW) of 24% (23.9–30.4 GHz) and a 3 dB ARBW of 21.7% (23.9–29.75 GHz), fully covering the entire 5G MMW band (24.25–29.5 GHz). Furthermore, a peak gain of 7.46 dBi is achieved within the operating bandwidth. The antenna of this invention has an in-passband IBW of 24%, a 3 dB ARBW of 21.7%, and a peak gain of 7.46 dBi. Moreover, out-of-band rejection exceeding 10 dB is achieved in both the upper and lower stopbands. The antenna structure of this invention is simple, easy to manufacture, and relatively low in cost and weight.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a circularly polarized filter grid slotted patch antenna based on a substrate integrated gap waveguide according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the upper surface of a first dielectric substrate according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the lower surface of a first dielectric substrate according to an embodiment of the present invention; Figure 4 This is a top view of a second dielectric substrate according to an embodiment of the present invention; Figure 5 A top view of a third dielectric substrate and a fourth dielectric substrate according to an embodiment of the present invention; Figure 6 The above is an S-parameter diagram of a circularly polarized filter grid slotted patch antenna based on a substrate integrated gap waveguide according to an embodiment of the present invention. Figure 7 The axial ratio curve of a circularly polarized filter grid slotted patch antenna based on a substrate integrated gap waveguide according to an embodiment of the present invention is shown. Figure 8 This is a gain curve of a slotted patch antenna with a circularly polarized filter grid based on a substrate-integrated gap waveguide according to an embodiment of the present invention. Figure label: 1. First dielectric substrate; 11. Chamfered square patch; 12. Chamfered rectangular patch; 2. Second dielectric substrate; 21. Cross strip; 22. Parasitic strip; 23. Circular ring; 3. Third dielectric substrate; 31. I-shaped rectangular slot; 32. Bifurcation microstrip feeding structure; 33. Folded strip; 4. Fourth dielectric substrate; 41. Circular patch; 42. Metal pillar; 5. First adhesive layer; 6. Second adhesive layer; 7. Third adhesive layer. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] The following description, with reference to the accompanying drawings, describes a compact circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide, according to an embodiment of the present invention.

[0020] like Figures 1 to 5 As shown, the circularly polarized filter grid slotted patch antenna based on substrate integrated gap waveguide of the present invention includes: a first dielectric substrate 1, a first adhesive layer 5, a second dielectric substrate 2, a second adhesive layer 6, a third dielectric substrate 3, a third adhesive layer 7 and a fourth dielectric substrate 4 stacked sequentially from top to bottom.

[0021] The upper surface of the first dielectric substrate 1 has four chamfered square patches 11 arranged in a 2×2 array at the center; the lower surface of the first dielectric substrate 1 has two chamfered rectangular patches 12 arranged in a 45-degree clockwise central symmetrical array; thus achieving circular polarization radiation.

[0022] A cross strip 21 is provided at the center of the upper surface of the second dielectric substrate 2, and four parasitic strips 22 surround the cross strip 21. The four parasitic strips 22 are of equal length and are equidistant from the center. This generates a new minimum axial ratio to significantly widen the axial ratio bandwidth.

[0023] A circular ring 23 is provided at the center of the lower surface of the second dielectric substrate 2; the lower stopband suppression is enhanced by introducing the first radiation zero point.

[0024] The upper surface of the third dielectric substrate 3 is provided with a metal ground structure, which is a rectangular metal patch of the same size as the third dielectric substrate 3, with an I-shaped rectangular slot 31 etched at the center. The lower surface of the third dielectric substrate 3 is provided with a feeding structure, which is a bifurcated microstrip feeding structure 32, with the bifurcation of the feeding structure perpendicular to the rectangular slot. The lower surface of the third dielectric substrate 3 is provided with two folded strips 33, which are located on both sides of the feeding structure. The bifurcated microstrip feeding structure 32 constitutes the SIGW feeding network, and the two folded strips 33 are used to generate a second radiation zero point to further optimize the lower stopband roll-off characteristics.

[0025] The fourth dielectric substrate 4 is an electromagnetic bandgap structure, which is a periodically arranged mushroom-shaped structural unit; the feeding structure of the third dielectric substrate 3 and the fourth dielectric substrate 4 together constitute the SIGW feeding network; the first dielectric substrate 1 and the second dielectric substrate 2 are connected by the first adhesive layer 5; the second dielectric substrate 2 and the third dielectric substrate 3 are connected by the second adhesive layer 6; the third dielectric substrate 3 and the fourth dielectric substrate 4 are connected by the third adhesive layer 7.

[0026] Specifically, the multilayer filter antenna provided by the present invention adopts a radiation structure composed of chamfered grid slot patches in the upper layer, a coupling and tuning structure composed of cross strips 21, parasitic strips 22 and circular rings 23 in the middle layer, and a low-loss feed network composed of SIGW in the lower layer, so as to achieve high-performance circular polarization radiation and filtering functions. Its working principle is as follows: the power supply energy is transmitted through the bifurcated microstrip power supply structure 32, and is excited by the cross strip 21 and parasitic strip 22 on the second dielectric substrate 22 via electromagnetic coupling, which in turn excites the grid slot patch (i.e., the chamfered square patch 11 and the chamfered rectangular patch 12) on the first dielectric substrate 1 to generate radiation; wherein, the grid slot patch introduces micro-perturbation through chamfering to achieve circular polarization radiation, and at the same time, the addition of the cross strip 21 and parasitic strip 22 introduces a new minimum axial ratio, which makes the axial ratio bandwidth performance within the working bandwidth better, thereby achieving better circular polarization radiation; the circular ring 23 and the folded strip 33 resonate at specific frequencies to form radiation zero points, further enhancing the filtering performance; the synergistic effect of the multilayer structure optimizes the electromagnetic field distribution and improves the energy coupling efficiency.

[0027] According to one embodiment of the present invention, such as Figure 2 As shown, the four chamfered square patches 11 are centrally symmetrical about the geometric center point of the upper surface of the first dielectric substrate 1. The chamfered angles of the four chamfered square patches 11 are the same, and the spacing between each pair of the four chamfered square patches 11 is the same. The shape of the chamfered square patches 11 is that two opposite corners of a square have a first isosceles right triangle cut off, and the right-angled side of the first isosceles right triangle is less than or equal to half the side length of the square.

[0028] According to one embodiment of the present invention, such as Figure 3 As shown, the two chamfered rectangular patches 12 are centrally symmetrical about the geometric center point of the lower surface of the first dielectric substrate 1. The chamfered rectangular patches 12 have the same chamfer angle and are centrally symmetrical about the geometric center point at 45 degrees. The shape of the chamfered rectangular patches 12 is such that a second isosceles right triangle is cut off from each of the four right angles of the rectangle. The right-angled side of the second isosceles right triangle is equal to half the length of the shorter side of the rectangle.

[0029] Specifically, in this invention, by adopting a chamfered design on the upper and lower radiation patches, structural disturbances are introduced to excite two orthogonal modes with equal amplitudes and a 90° phase difference, thereby generating left-hand circularly polarized radiation at the initial frequency fAR1 and forming the first minimum axial ratio.

[0030] According to one embodiment of the present invention, such as Figure 4 As shown, the cross strip 21 is centrally symmetrical about the geometric center point of the upper surface of the second dielectric substrate 2, and the four parasitic strips 22 are located outside the four opening directions of the cross strip 21. The four parasitic strips 22 are equidistant from the geometric center point of the upper surface of the second dielectric substrate 2.

[0031] Specifically, by setting cross strips 21 and parasitic strips 22 on the upper surface of the second dielectric substrate 2, a new resonant mode can be excited, generating a second minimum axial ratio at a higher frequency fAR2. By reasonably adjusting the length of the cross strips 21, the position of fAR2 can be controlled so that it, together with fAR1, forms a 3dB axial ratio bandwidth of up to 27.8%.

[0032] According to one embodiment of the present invention, such as Figure 4 As shown, a circular ring 23 is etched on the lower surface of the second dielectric substrate 2, and the center of the circular ring 23 is the geometric center of the lower surface of the second dielectric substrate 2.

[0033] Specifically, in this invention, a circular ring 23 is etched on the lower surface of the second dielectric substrate 2, which effectively improves the out-of-band suppression characteristics of the antenna in the low-frequency band. The circular ring 23 resonates at a specific frequency fn1, and its surface current distribution is opposite to that of the radiating patch. Most of the energy is confined to the circular ring 23 itself, and only a small amount of energy is coupled to the radiating patch. Therefore, a radiation null point is generated at fn1, which significantly enhances the suppression level of the low-frequency stopband.

[0034] According to one embodiment of the present invention, the I-shaped rectangular slots 31 are laterally distributed at the center of the metal ground structure and are centrally symmetrical about the geometric center point of the metal ground structure. Energy is coupled to the upper-layer radiating patch structure through the I-shaped rectangular slots 31.

[0035] According to one embodiment of the present invention, the power feeding structure includes a first microstrip line, a first transition structure, a second transition structure, and two second microstrip lines connected in sequence; wherein, the first microstrip lines are longitudinally distributed at the geometric center point of the lower surface of the third dielectric substrate 3, one end of the first microstrip line is connected to the center position of the first transition structure, the first transition structure is connected to the center position of the second transition structure, the two second microstrip lines are respectively connected to the two ends of the second transition structure, and the two second microstrip lines are perpendicular to the rectangular gap.

[0036] According to one embodiment of the present invention, the two folded strips 33 are in a square waveform structure, distributed on both sides of the power supply structure, and are symmetrical about the line of symmetry of the power supply structure.

[0037] According to one embodiment of the present invention, the upper surface of the mushroom-shaped structural unit is a plurality of circular patches 41 arranged in an array, and the lower surface of the mushroom-shaped structural unit is a rectangular metal patch of the same size as the fourth dielectric substrate 4. The plurality of circular patches 41 and the rectangular metal patch of the mushroom-shaped structural unit are connected by metal pillars 42.

[0038] Specifically, the frequency selectivity is further enhanced by adding a folded strip 33 to the power supply network in this invention. When the total length of the folded strip 33 is equal to half the wavelength corresponding to its resonant frequency fn2, the stub exhibits high impedance characteristics, hindering energy transmission to the radiation port, thereby generating a second radiation null at fn2 and optimizing the stopband roll-off characteristics.

[0039] According to one embodiment of the present invention, the first dielectric substrate 1, the second dielectric substrate 2, the third dielectric substrate 3 and the fourth dielectric substrate 4 are made of Rogers 3003, with a dielectric constant of 3, a relative permeability of 1 and a loss tangent of 0.0013.

[0040] In one example, the first dielectric substrate 1 is made of Rogers 3003 and has a thickness h1 of 0.51 mm; the second dielectric substrate 2 is made of Rogers 3003 and has a thickness h2 of 0.25 mm; the third dielectric substrate 3 is made of Rogers 3003 and has a thickness h3 of 0.25 mm; and the fourth dielectric substrate 4 is made of Rogers 3003 and has a thickness h4 of 1.52 mm.

[0041] According to one embodiment of the present invention, the first adhesive layer 5, the second adhesive layer 6 and the third adhesive layer 7 are made of Rogers 4450F, with a dielectric constant of 3.52, a relative permeability of 1, a loss tangent of 0.004 and a thickness of 0.2 mm.

[0042] According to one embodiment of the present invention, the materials of the chamfered square patch 11, the chamfered rectangular patch 12, the cross strip 21, the parasitic strip 22, the circular ring 23, the metal ground, the power supply structure, the folded strip 33, and the electromagnetic bandgap structure are all copper, silver, or gold, the same materials used in printed circuits.

[0043] The following is for reference. Figures 1 to 8 This invention provides a detailed description of a specific embodiment of a circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide.

[0044] The main dimensions of the antenna are as follows: The chamfered rectangular patch 11 has a length (lp1) of 1.8 mm, a width (wp1) of 1.8 mm, a chamfer size (ct1) of 0.2 mm, and a gap width (wd1) of 0.15 mm between patches; the chamfered rectangular patch 12 has a width (wp2) of 1.64 mm, a hypotenuse width (wp3) of 0.64 mm, and a distance (wd2) between the two patches of 0.21 mm; the cross strip 21 has a length (lt2) of 1.39 mm and a width (wt2) of 0.12 mm; the four parasitic strips 22 have a length (lt1) of 0.82 mm, a width (wt1) of 0.12 mm, and a distance (wr2) from the center of the cross strip 21 of 0.74 mm; the circular ring 23 has a radius (wr1) of 1.25 mm; the I-shaped rectangular slot 31 in the metal ground has a horizontal slot length (ls1) of 2.3 mm and a width (ws) of 2.3 mm. 1 is 0.22mm, the length ls2 of the vertical gap is 0.95mm, and the width ws2 is 0.12mm; in the feeding structure, the width wt5 of the first microstrip line is 0.45mm, the length lt6 of the first transition structure is 1.84mm, and the width wt6 is 0.24mm, the length lt7 of the second transition structure is 2.09mm, and the width wt7 is 0.14mm, the length lt8 of the second microstrip line is 1.63mm, and the width wt8 is 0.16mm; the folding length lt3 of the folded strip 33 is 0.97mm, and the folding spacing wt4 of the folded strip 33 is 0.12mm; the diameter wr4 of the circular patch 41 of the electromagnetic bandgap structure unit is 1mm, the diameter wr3 of the metal pillar 42 of the electromagnetic bandgap structure unit is 0.3mm, and the period wr5 of the electromagnetic bandgap structure unit is 1.5mm.

[0045] Combination Figure 6 It can be seen that the antenna operates in the frequency band of 23.9-30.4 GHz, and its in-band reflection coefficient |S11| is less than -10dB. The antenna's -10dB bandwidth is 6.5 GHz, and its relative bandwidth is 24%. Figure 7 The data also shows that the antenna's 3dB axial ratio bandwidth is 21.7% (23.9-29.75 GHz). Figure 8 As can be seen, the antenna has a flat gain within the passband, with a peak gain of 7.46 dBi. Its out-of-band rejection level is better than 15 dB in the low-frequency band and better than 10 dB in the high-frequency band, indicating good filtering performance.

[0046] The compact circularly polarized filter grid slotted patch antenna based on substrate integrated gap waveguide of this invention includes four dielectric substrates. The first dielectric substrate 1 and the second dielectric substrate 2 together achieve wideband circularly polarized radiation characteristics. The third dielectric substrate 3 and the fourth dielectric substrate 4 constitute a low-loss SIGW feed network. By loading a circular ring 23 onto the second dielectric substrate 2, a radiation null point fn1 is formed at low frequencies. Simultaneously, by embedding a folded strip 33 within the third dielectric substrate 3, a second radiation null point fn2 is generated, further improving out-of-band suppression capability. Ultimately, the antenna achieves high out-of-band suppression and a compact design while fully covering the 5G millimeter-wave band.

[0047] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A slotted patch antenna with circularly polarized filter grid based on a substrate-integrated gap waveguide, characterized in that, include: The first dielectric substrate, the first adhesive layer, the second dielectric substrate, the second adhesive layer, the third dielectric substrate, the third adhesive layer, and the fourth dielectric substrate are stacked sequentially from top to bottom, wherein: Four chamfered square patches are provided at the center of the upper surface of the first dielectric substrate, and the four chamfered square patches are arranged in a 2×2 array; the shape of the chamfered square patch is a square with two opposite corners cut off to form a first isosceles right triangle, and the right-angled side of the first isosceles right triangle is less than or equal to half the side length of the square; Two chamfered rectangular patches are provided at the center of the lower surface of the first dielectric substrate. The two chamfered rectangular patches are symmetrically arranged in a clockwise direction at 45 degrees. The shape of the chamfered rectangular patches is that a second isosceles right triangle is cut off from each of the four right angles of the rectangle. The right angle side of the second isosceles right triangle is equal to half the short side of the rectangle. A cross strip is provided at the center of the upper surface of the second dielectric substrate, and four parasitic strips surround the cross strip. The four parasitic strips are of equal length and the distance between the four parasitic strips is equal to the distance between the geometric center point of the upper surface of the second dielectric substrate. A circular ring is provided at the center of the lower surface of the second dielectric substrate; The upper surface of the third dielectric substrate is provided with a metal ground structure, which is a rectangular metal patch of the same size as the third dielectric substrate and has an I-shaped rectangular slit etched in the center. The lower surface of the third dielectric substrate is provided with a feeding structure, which is a bifurcated microstrip feeding structure. The feeding structure includes a first microstrip line, a first transition structure, a second transition structure, and two second microstrip lines connected in sequence. The first microstrip line is longitudinally distributed at the geometric center point of the lower surface of the third dielectric substrate. One end of the first microstrip line is connected to the center position of the first transition structure. The first transition structure is connected to the center position of the second transition structure. The two second microstrip lines are respectively connected to the two ends of the second transition structure, and the two second microstrip lines are perpendicular to the rectangular gap. The lower surface of the third dielectric substrate is provided with two folded strips, which are located on both sides of the feeding structure. The fourth dielectric substrate is an electromagnetic bandgap structure, which is a periodically arranged mushroom-shaped structural unit. The feeding structure of the third dielectric substrate and the fourth dielectric substrate together constitute the SIGW feeding network. The first dielectric substrate and the second dielectric substrate are connected by the first adhesive layer; The second dielectric substrate and the third dielectric substrate are connected by the second adhesive layer; The third dielectric substrate and the fourth dielectric substrate are connected by the third adhesive layer.

2. The circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide according to claim 1, characterized in that, The four chamfered square patches are symmetrical about the geometric center point of the upper surface of the first dielectric substrate, the chamfered angles of the four chamfered square patches are the same, and the spacing between each pair of the four chamfered square patches is the same.

3. The circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide according to claim 1, characterized in that, The two chamfered rectangular patches are centrally symmetrical about the geometric center point of the lower surface of the first dielectric substrate, the chamfered angles of the two chamfered rectangular patches are the same, and the two chamfered rectangular patches are centrally symmetrical about the geometric center point at 45 degrees.

4. The circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide according to claim 1, characterized in that, The cross strips are symmetrical about the geometric center point of the upper surface of the second dielectric substrate, and the four parasitic strips are located outside the four opening directions of the cross strips. The four parasitic strips are equidistant from the geometric center point of the upper surface of the second dielectric substrate.

5. The circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide according to claim 1, characterized in that, The circular ring is etched on the lower surface of the second dielectric substrate, and the center of the circular ring is the geometric center of the lower surface of the second dielectric substrate.

6. The circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide according to claim 1, characterized in that, The I-shaped rectangular gaps are distributed laterally at the center of the metal ground structure and are centrally symmetrical about the geometric center point of the metal ground structure.

7. The circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide according to claim 1, characterized in that, The two folded strips have a square waveform structure, are distributed on both sides of the power supply structure, and are symmetrical about the line of symmetry of the power supply structure.

8. The circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide according to claim 1, characterized in that, The upper surface of the mushroom-shaped structural unit consists of multiple circular patches arranged in an array, and the lower surface of the mushroom-shaped structural unit consists of a rectangular metal patch of the same size as the fourth dielectric substrate. The multiple circular patches and the rectangular metal patch of the mushroom-shaped structural unit are connected by metal pillars.

9. The circularly polarized filter grid slotted patch antenna based on a substrate-integrated gap waveguide according to claim 1, characterized in that, The materials of the chamfered square patch, the chamfered rectangular patch, the cross strip, the parasitic strip, the circular ring, the metal ground, the power supply structure, the folded strip, and the electromagnetic bandgap structure are all copper, silver, or gold.

Images