A broadband, highly integrated substrate-integrated waveguide horn antenna

Abstract

The present invention discloses a broadband, highly integrated substrate-integrated waveguide horn antenna, relating to the field of communications technology, particularly antenna technology. The antenna comprises a dielectric coating and an antenna layer structure. The antenna layer structure includes a substrate-integrated waveguide horn printed on a dielectric substrate and a loading structure. The loading structure further comprises an offset parallel double-sided structure of etched slots and a defective ground structure. The substrate-integrated waveguide horn comprises a semi-open resonant cavity widened from the H-plane of the substrate-integrated waveguide, a coaxial feeding structure, and a third-order ridge structure. The offset parallel double-sided structure of etched slots is distributed directly in front of the horn opening of the substrate-integrated waveguide horn, and the defective ground structure is distributed at the edge of the horn aperture of the substrate-integrated waveguide horn. Specifically, the defective ground structure comprises two pairs of symmetrical slots etched on the upper surface of the antenna layer dielectric substrate. The present invention has the excellent characteristics of high integration, stable end-fire, and wide bandwidth, and is suitable for conformal integration applications on small aircraft.

Description

Technical Field

[0001] The present invention belongs to the technical field of antennas, and in particular relates to a broadband highly integrated substrate integrated waveguide horn antenna. Background Art

[0002] With the rapid development of modern science and technology, society requires wider bandwidth and more easily installed or portable antennas to transmit the explosive growth of information. Therefore, the overall performance of the antenna has a significant impact on the operation of the entire system. Traditional H-plane horn antennas are widely used in wireless communications due to their wide bandwidth and stable end-fire characteristics. However, their non-planar structure limits their further application in miniaturization and integration. The emerging microwave transmission technology - substrate-integrated waveguide technology - can effectively solve this problem, enabling the design of traditional H-plane horn antennas in a planar manner. However, due to the mismatch in dielectric constant between the substrate-integrated waveguide substrate and air, the designed antenna has a narrow bandwidth, which makes it difficult to meet the requirements of broadband communication. Therefore, how to achieve wide bandwidth and small size while maintaining good radiation performance of the horn antenna is of great research value.

[0003] To expand the bandwidth of substrate-integrated waveguide horn antennas, existing technologies include modifying the profile of the traditional H-shaped horn to a superelliptical taper, introducing an extended dielectric plate in front of the horn aperture to act as an impedance transformer, and adding air holes with gradient diameters or printed transition structures to the extended dielectric plate. However, all of these technologies increase the size of the antenna, making it difficult to install and use in confined spaces.

[0004] To address these issues, the present invention provides a substrate-integrated waveguide ridge horn antenna featuring an offset parallel double-sided structure with two sets of etched slots and a defective ground. This unique structure significantly expands the antenna's bandwidth while maintaining a compact size and stable end-fire radiation performance, meeting the requirements of broadband wireless communications. Summary of the Invention

[0005] The present invention discloses a broadband, highly integrated substrate-integrated waveguide horn antenna, which effectively broadens the antenna bandwidth and improves the end-fire performance of the antenna, and has the excellent characteristic of high integration.

[0006] The above purpose is achieved through the following technical solutions:

[0007] A broadband, highly integrated substrate-integrated waveguide horn antenna comprises a dielectric cladding and an antenna layer structure. The antenna layer structure comprises a substrate-integrated waveguide horn printed on a dielectric substrate and a loading structure. The loading structure further comprises an offset parallel double-sided structure with etched slots and a defective ground structure. The substrate-integrated waveguide horn comprises a semi-open resonant cavity widened from the H-plane of the substrate-integrated waveguide, a coaxial feeding structure, and a third-order ridge structure. The inner conductor of the coaxial feeding structure contacts the upper ridge of the third-order ridge structure, and the outer conductor of the coaxial feeding structure connects to the lower bottom surface of the dielectric substrate. The offset parallel double-sided structure with etched slots is distributed directly in front of the horn mouth of the substrate-integrated waveguide horn, and the defective ground structure is distributed at the edge of the horn aperture of the substrate-integrated waveguide horn. Specifically, it comprises two pairs of symmetrical slots etched on the upper surface of the antenna layer dielectric substrate.

[0008] Furthermore, the semi-open resonant cavity is formed by a metal through-hole with a diameter of 0.4 mm and surrounded by four equally spaced extension segments along a semicircular arc with a radius of r1. The lengths of the four extension segments are l1, l2, l3, and l4, respectively, and w1, w2, and w3 are widths at different positions. The opening angle of the resonant cavity is adjusted by adjusting the lengths of l1, l2, l3, and l4, the widths w1, w2, and w3 at different positions, and the size of each ridge of the three-order ridge structure, thereby adjusting the antenna impedance and realizing a broadband substrate-integrated waveguide horn.

[0009] The opening width of the substrate integrated waveguide horn is derived from the geometric relationship of the horn mouth as follows:

[0010]

[0011] Where δ is the adjustment coefficient and λ is the wavelength of electromagnetic wave propagation in the dielectric substrate:

[0012]

[0013] where μ r and ε r are the relative permittivity and relative permeability of the dielectric substrate FR4, λ0 is the wavelength of the free space electromagnetic wave;

[0014] The opening angle of the substrate integrated waveguide horn is calculated using the following formula: The calculation formula is as follows:

[0015] Furthermore, the adjustment coefficient is generally set to 0.1-0.4λ.

[0016] Furthermore, the offset parallel double-sided structure of the etched slots is a structure in which four parallel surface structures are arranged on the front and back surfaces of the dielectric substrate distributed directly in front of the horn mouth of the substrate-integrated waveguide horn. The four parallel surface structures on the front and back surfaces include two pairs of parallel surfaces etched with T-shaped slots and two pairs of parallel surfaces etched with umbrella-shaped slots. The dimensions of each two pairs of parallel surface structures are the same, wherein the T-shaped slot patterns on the front and back surfaces of the dielectric substrate have an offset distance of 0.5 mm on the x-axis; and the umbrella-shaped slot patterns on the front and back surfaces of the dielectric substrate have an offset distance of 1 mm on the x-axis.

[0017] Furthermore, the defect structure is specifically two pairs of y-axis symmetrical gaps etched on the upper surface of the antenna layer dielectric substrate; distributed at the edge of the horn aperture of the substrate-integrated waveguide horn, wherein the gap away from the horn aperture edge is 3 mm long and 0.1 mm away from the end of the horn aperture edge. The second gap is approximately 0.5 mm apart from the first gap and has a length of 2 mm.

[0018] Furthermore, the dielectric substrate in the antenna layer structure adopts a 2.6 mm thick F4B board with a dielectric constant of 2.65;

[0019] Furthermore, the dielectric coating is made of a 1.1 mm thick FR4 board with a dielectric constant of 4.4.

[0020] Compared with the prior art, the present invention has the following significant advantages:

[0021] 1) The biased parallel double-sided structure with two sets of slots etched in the load makes the real part of the antenna impedance closer to 50Ω and the imaginary part closer to 0Ω in the X and Ku bands, thus achieving broadband characteristics;

[0022] 2) The defect-loaded ground structure optimizes the antenna's end-fire performance and reduces backward radiation;

[0023] 3) It has the characteristics of small size, light weight, easy integration and easy conformality. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a top view of the antenna structure;

[0025] Figure 2 It is a side view of the antenna structure;

[0026] Figure 3 It is a substrate-integrated waveguide horn structure;

[0027] Figure 4 Schematic diagram of the substrate integrated waveguide horn structure

[0028] Figure 5 Load etching of offset parallel double-sided with gaps;

[0029] Figure 6Schematic diagram of the loading bias parallel double-sided structure;

[0030] Figure 7 Comparison of standing wave ratio and impedance after biasing parallel double-sided structure in the embodiment;

[0031] Figure 8 This is a comparison diagram of the standing wave ratio after etching the first group of slits in the embodiment;

[0032] Figure 9 A comparison diagram of surface current distribution after etching the first set of slits in the embodiment;

[0033] Figure 10 This is a comparison diagram of the standing wave ratio and impedance after etching the second set of slits in the embodiment;

[0034] Figure 11 This is a schematic diagram of the structure after the defective ground is loaded in the embodiment;

[0035] Figure 12 For the embodiment defect ground structure changes the aperture edge current direction diagram;

[0036] Figure 13 A comparison diagram of antenna gain and backward radiation after loading a defective ground structure in the embodiment;

[0037] Figure 14 This is a result diagram of the antenna shown in the embodiment;

[0038] Description of the component numbers in the figure:

[0039] 1. Antenna layer structure; 2. Dielectric cladding; 1-1. Dielectric substrate; 1-2. Substrate-integrated waveguide horn; 1-3. Loading structure; 1-3-1. Biased parallel double-sided structure; 1-3-2. Defective ground structure; 1-2-1. Semi-open resonant cavity; 1-2-2. Coaxial feeding structure; 1-2-3. Third-order ridge structure. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0041] This embodiment provides a broadband, highly integrated substrate integrated waveguide horn antenna. Figure 1 and Figure 2 As shown, the size of the antenna is approximately 1.4λ0×0.8λ0×0.16λ0, Figure 1 The above l and w correspond to the length and width of the antenna respectively, l = 1.4λ0, w = 0.8λ0, where λ0 is the wavelength of the electromagnetic wave in free space, which is the ratio of the speed of light c to the frequency f:

[0042] λ0=c / f

[0043] The broadband, highly integrated substrate-integrated waveguide horn antenna of this embodiment consists of a dielectric cladding 2 and an antenna layer structure 1. The dielectric cladding adopts a 1.1 mm thick FR4 board with a dielectric constant of 4.4; the antenna layer structure 1 includes a substrate-integrated waveguide horn 1-2 and a loading structure 1-3 printed on a dielectric substrate 1-1. In this embodiment, the dielectric substrate adopts a 2.6 mm thick F4B board with a dielectric constant of 2.65; the loading structure further includes an offset parallel double-sided structure 1-3-1 with etched gaps and a defective ground structure 1-3-2.

[0044] The substrate integrated waveguide horn 1-2 is composed of a semi-open resonant cavity 1-2-1 widened by the H-plane of the substrate integrated waveguide, a coaxial feeding structure 1-2-2 and a third-order ridge structure 1-2-3. Figure 3 As shown; the inner conductor of the coaxial feeding structure 1-2-2 contacts the upper ridge of the third-order ridge structure 1-2-3, and the outer conductor of the coaxial feeding structure 1-2-2 is connected to the lower bottom surface of the dielectric substrate 1-1; the semi-open resonant cavity 1-2-1 is formed by a metal through hole with a diameter of 0.4 mm along a semicircular arc with a radius of r1 and four equidistantly arranged extension segments. Figure 4 The l1, l2, l3, and l4 shown are the lengths of each extension segment, and w1, w2, and w3 are the widths at different positions. By adjusting the lengths l1, l2, l3, and l4 of each extension segment, the widths w1, w2, and w3 at different positions, and the size of each ridge of the three-order ridge structure, the opening angle of the resonant cavity is adjusted, thereby adjusting the antenna impedance and realizing a wide-bandwidth substrate-integrated waveguide horn.

[0045] The opening width of the substrate integrated waveguide horn 1-2 can be derived from the geometric relationship of the horn mouth as follows:

[0046]

[0047] The value of δ is generally 0.1-0.4 electrical lengths, and δ = 0.22λ is taken. Considering that the antenna should be as small as possible, l1,

[0048] The sum of l2, l3, and l4 is 1.2λ, where λ is the wavelength of electromagnetic wave propagation in the dielectric substrate:

[0049]

[0050] where μ r and ε r is the relative dielectric constant and relative magnetic permeability of the dielectric substrate FR4; further, it can be deduced that w3 is about 17mm, and the opening angle can be calculated using the following formula It is about 30°, and the calculation formula is as follows:

[0051]

[0052] The three-order ridge structure with gradually decreasing height is adjusted directly through optimization simulation. In this embodiment, the sizes of the three ridge sections along the radiation direction are 6.2mm*4.1mm*1.6mm, 5.3mm*3.8mm*1.2mm, and 1.8mm*3.2mm*0.6mm, respectively.

[0053] Figure 5 This is a schematic diagram of the structure of the biased parallel double-sided structure 1-3-1. The biased parallel double-sided structure 1-3-1 is distributed directly in front of the horn mouth of the substrate-integrated waveguide horn and is located on both sides of the dielectric substrate. Four parallel surface structures are provided on each of the front and back sides of the dielectric substrate. The four parallel surface structures on each of the front and back sides include two pairs of parallel surfaces etched with T-shaped slots and two pairs of parallel surfaces etched with umbrella-shaped slots. The dimensions of each pair of parallel surface structures on the dielectric substrate are identical, with lengths lp1 and lp2 of approximately 5 mm and widths wp1 and wp2 of approximately 8 mm. In this embodiment, a coordinate system is established with the direction of the horn mouth of the parallel substrate-integrated waveguide horn on the dielectric substrate as the x-axis and the y-axis perpendicular to the horn mouth of the parallel substrate-integrated waveguide horn as the horn mouth direction of the parallel substrate-integrated waveguide horn for description.

[0054] The parallel surface etched with the T-shaped slot is 1.3 mm from the upper edge of the dielectric substrate g2, and the gap between it and the substrate-integrated waveguide horn is approximately 0.2 mm. The T-shaped slot patterns on the front and back sides of the dielectric substrate have an offset distance of 0.5 mm on the x-axis. The two pairs of parallel surfaces etched with umbrella-shaped slots are close to the upper right corner of the dielectric substrate, and are separated by g3 along the x-axis by 1.5 mm. The umbrella-shaped slot patterns on the front and back sides of the dielectric substrate have an offset distance of 1 mm on the x-axis.

[0055] The biased parallel double-sided structure adjusts the input impedance of the antenna at low and medium frequencies, and expands the frequency band of the antenna to low frequencies, such as Figure 7 shown.

[0056] The T-shaped gap is divided into two parts s1 and s2, such as Figure 6 As shown in the figure, s1 is 2.5mm long and 0.2mm wide, and is 1.9mm away from the starting edge g1 of the parallel plane along the y-axis. A 3mm long slot s2 is connected to the end of s1 along the x-axis. A high-frequency resonance point at 17.4GHz is introduced by etching the first set of slots, which expands the bandwidth of the antenna to high frequencies, as shown in the figure. Figure 8 The results show that Figure 9 From the perspective of the current distribution diagram, it is intuitively shown that the antenna has high-frequency resonance at the first set of gaps.

[0057] The umbrella-shaped gap is divided into two parts s3 and s4, as shown in Figure 6As shown in the figure, s3 is about 3mm away from the left side of the parallel plane and g4, the gap is 3mm long, s4 is a semicircular gap with a diameter of 3mm, and the center of the gap is located at the top of s3; by introducing the second set of gaps, the input impedance of the antenna at medium and high frequencies is further optimized, making the overall input impedance of the antenna closer to 50Ω in the real part and closer to 0Ω in the imaginary part, optimizing the matching performance of the antenna and thus widening the antenna bandwidth, as shown in the figure. Figure 10 shown.

[0058] Figure 11 This is a schematic diagram after loading the defective ground structure 1-3-2. The defective ground structure 1-3-2 is distributed at the edge of the speaker aperture. Specifically, it is two pairs of symmetrical slits along the y-axis etched on the upper surface of the antenna layer dielectric substrate. The slit away from the speaker is 3mm long and about 0.1mm away from the end of the speaker. The second slit is about 0.5mm away from the first and has a length of 2mm. Figure 12 As shown in the figure, the loading structure changes the current flow direction at the edge of the horn aperture, which significantly reduces the backward radiation without deteriorating the antenna gain and improves the end-fire performance of the antenna. The result is shown in Figure 13 middle.

[0059] The standing wave ratio and gain results of the antenna provided by the present invention are shown in Figure 14 In the figure, it can be seen that broadband is achieved while maintaining good radiation performance.

[0060] The above are only the best embodiments of the present invention, but the present invention is not limited to the above embodiments. The above specific implementation methods are only illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which are all protected by the present invention.

Claims

1. A broadband, highly integrated substrate-integrated waveguide horn antenna, comprising a dielectric cladding and an antenna layer structure, characterized in that: The antenna layer structure includes a substrate-integrated waveguide horn and a loading structure printed on a dielectric substrate. The loading structure further includes an offset parallel double-sided structure of etched slots and a defective ground structure. The substrate-integrated waveguide horn is composed of a semi-open resonant cavity widened by the H-plane of the substrate-integrated waveguide, a coaxial feeding structure, and a third-order ridge structure. The inner conductor of the coaxial feeding structure contacts the upper ridge of the third-order ridge structure, and the outer conductor of the coaxial feeding structure contacts the lower bottom surface of the dielectric substrate. The offset parallel double-sided structure of the etched slots is distributed directly in front of the horn mouth of the substrate-integrated waveguide horn, and the defective ground structure is distributed at the edge of the horn aperture of the substrate-integrated waveguide horn. Specifically, it is two pairs of symmetrical slots etched on the upper surface of the antenna layer dielectric substrate. The offset parallel double-sided structure of the etched slots comprises four parallel surface structures disposed on each of the front and back surfaces of the dielectric substrate directly in front of the horn opening of the substrate-integrated waveguide horn. The four parallel surface structures on each of the front and back surfaces include two pairs of parallel surfaces etched with T-shaped slots and two pairs of parallel surfaces etched with umbrella-shaped slots. The dimensions of each pair of parallel surface structures are identical. A coordinate system is established with the direction of the horn opening of the substrate-integrated waveguide horn on the dielectric substrate being parallel as the x-axis and the direction perpendicular to the horn opening of the substrate-integrated waveguide horn being perpendicular as the y-axis. The T-shaped slot patterns on the front and back surfaces of the dielectric substrate have an offset distance of 0.5 mm on the x-axis, and the umbrella-shaped slot patterns on the front and back surfaces of the dielectric substrate have an offset distance of 1 mm on the x-axis. The defective ground structure specifically consists of two pairs of y-axis symmetrical slits etched on the upper surface of the antenna layer dielectric substrate; distributed at the edge of the horn aperture of the substrate-integrated waveguide horn, the slit farthest from the horn aperture edge is 3 mm long and 0.1 mm from the end of the horn aperture edge. The second slit is 0.5 mm apart from the first and is 2 mm long.

2. The broadband highly integrated substrate integrated waveguide horn antenna according to claim 1, characterized in that: The semi-open resonant cavity is formed by a metal through-hole with a diameter of 0.4 mm along a semicircular arc with a radius of r1 and four equally spaced extension segments. The lengths of the four extension segments are l1, l2, l3, and l4, respectively. The width of the extension segment with a length of l1 is w1. The extension segment with a length of l2 is a transition segment, and its two ends are respectively connected to the extension segment with a length of l1 and the extension segment with a length of l2. The width of one end connected to the extension segment with a length of l1 is w1, and the width of one end connected to the extension segment with a length of l3 is w2. The width of the extension section of length l3 is w2; the extension section of length l4 is a transition section, with its two ends connecting the extension section of length l3 and the horn, respectively. The width of the end connected to the extension section of length l3 is w2, and the width of the end connected to the horn is w3. By adjusting the lengths of l1, l2, l3, and l4, the widths w1, w2, and w3 at different positions, and the size of each ridge of the three-order ridge structure, the opening angle of the resonant cavity is adjusted, thereby adjusting the antenna impedance and realizing a broadband substrate-integrated waveguide horn. The opening width of the substrate integrated waveguide horn is derived from the geometric relationship of the horn mouth as follows: Where δ is the adjustment coefficient and λ is the wavelength of electromagnetic wave propagation in the dielectric substrate: where μ r and ε r are the relative permittivity and relative permeability of the dielectric substrate FR4, λ0 is the wavelength of the free space electromagnetic wave; The opening angle of the substrate integrated waveguide horn is calculated using the following formula: The calculation formula is as follows:

3. The broadband highly integrated substrate integrated waveguide horn antenna according to claim 2, characterized in that: The adjustment coefficient is 0.1λ-0.4λ.

4. The broadband highly integrated substrate integrated waveguide horn antenna according to claim 1, characterized in that: The dielectric substrate in the antenna layer structure adopts a 2.6mm thick F4B board with a dielectric constant of 2.65; 5. The broadband highly integrated substrate integrated waveguide horn antenna according to claim 1, characterized in that: The dielectric coating is a 1.1 mm thick FR4 board with a dielectric constant of 4.4.

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