A millimeter wave SIW horn antenna loaded with EBG surface

Abstract

The present invention discloses a millimeter wave SIW horn antenna loaded with an EBG surface, belonging to the field of antenna microwave technology. The present invention comprises an upper EBG layer metal plate (4), an upper EBG layer dielectric substrate (1), an upper radiation layer metal plate (5), a radiation layer dielectric substrate (2), a lower radiation layer metal plate (6), a lower EBG layer dielectric substrate (3) and a lower EBG layer metal plate (7) which are pressed together in sequence, and a feed layer metal plate (8) interconnected coplanarly with the upper radiation layer metal plate (5), and a feed layer metal ground (9) interconnected coplanarly with the lower radiation layer metal plate (6); a metal patch array and metallized vias (10) are distributed on the upper EBG layer metal plate (4); the upper and lower EBG layer metal plates have the same structure, and the upper and lower EBG layer dielectric substrates have the same structure; a plurality of SIW horn cavity metallized vias (11) are equivalent to rectangular metal waveguides. The present invention provides a small-caliber millimeter wave SIW horn antenna loaded with an EBG surface, with high front-to-back ratio and high gain.

Description

Technical Field

[0001] The present invention belongs to the field of antenna microwave technology, and in particular relates to a millimeter wave SIW (Substrate integrated waveguide) horn antenna loaded with an EBG (Electromagnetic Band Gap) structure. Background Art

[0002] As the traditional microwave band electromagnetic spectrum becomes increasingly scarce, millimeter wave band wireless applications are becoming more and more widespread. In millimeter wave band wireless applications, such as point-to-point high-speed communication, high-resolution radar, etc., the demand for antenna miniaturization, high integration and low cost is increasing.

[0003] Traditional horn antennas have advantages such as high front-to-back ratio (front-to-back ratio = forward energy / backward energy) and high gain, but their high profile and large volume limit their application in millimeter wave, especially in millimeter wave scanning arrays. SIW (Substrate integrated waveguide) technology uses two rows of metallized via structures on a dielectric substrate to be equivalent to a rectangular metal waveguide. The gradually opened metal via structure can be equivalent to an H-plane horn wall, where the H plane refers to a plane containing a magnetic field vector and a maximum radiation direction. The H-plane SIW horn antenna using SIW technology has a small profile, a simple structure, and is easy to integrate with active circuits, so it has a good development prospect in the millimeter wave band. However, due to factors such as the thin thickness of the dielectric sheet and the high dielectric constant, the millimeter wave H-plane SIW horn antenna also has disadvantages such as difficult matching, high backlobe level, and low gain. In addition, due to the poor matching performance of the high dielectric constant dielectric substrate, the aperture length of the millimeter wave H-plane SIW horn antenna is difficult to reduce to within 1 wavelength of the center operating frequency, and the application of the millimeter wave H-plane SIW horn antenna in active arrays is greatly limited. Therefore, it is of great value to design a millimeter-wave H-plane SIW horn antenna with small aperture, low back lobe (i.e., high front-to-back ratio), and high gain by improving the structure of the traditional millimeter-wave H-plane SIW horn antenna. Summary of the invention

[0004] The invention aims to provide a small-caliber millimeter-wave SIW horn antenna with high front-to-back ratio and high gain and loaded with an EBG surface.

[0005] Specifically, the present invention provides a millimeter wave SIW horn antenna loaded with an EBG surface, comprising an upper EBG layer metal plate 4, an upper EBG layer dielectric substrate 1, an upper radiation layer metal plate 5, a radiation layer dielectric substrate 2, a lower radiation layer metal plate 6, a lower EBG layer dielectric substrate 3 and a lower EBG layer metal plate 7 which are pressed together in sequence, and a feed layer metal plate 8 interconnected coplanarly with the upper radiation layer metal plate 5, and a feed layer metal ground 9 interconnected coplanarly with the lower radiation layer metal plate 6;

[0006] A metal patch array is distributed on the upper EBG layer metal plate 4; a metallized via 10 penetrates the upper EBG layer metal plate 4 and the upper EBG layer dielectric substrate 1 to form a via array, and the center of the metallized via 10 is consistent with the center of the corresponding metal patch;

[0007] The lower EBG layer metal plate 7 has the same structure as the upper EBG layer metal plate 4 , and the lower EBG layer dielectric substrate 3 has the same structure as the upper EBG layer dielectric substrate 1 ;

[0008] A number of SIW horn cavity metallized vias 11 penetrate the upper radiation layer metal plate 5, the lower radiation layer metal plate 6 and the radiation layer dielectric substrate 2, starting from the side of the upper radiation layer metal plate 5 interconnected with the feed layer metal plate 8, and gradually spread out symmetrically to the other side of the upper radiation layer metal plate 5, which is equivalent to a rectangular metal waveguide.

[0009] Furthermore, the upper EBG layer dielectric substrate 1 , the radiation layer dielectric substrate 2 , and the lower EBG layer dielectric substrate 3 are all made of LTCC (Low Temperature Co-fired Ceramic) plates or PTEE (polytetrafluoroethylene) microwave plates.

[0010] Furthermore, the metal patch array consists of rectangular metal patches.

[0011] Furthermore, the sides of the rectangular metal patches are equal in length.

[0012] Furthermore, the upper EBG layer metal plate 4 is divided into a rectangular metal patch array by rectangular transverse grooves and rectangular longitudinal grooves etched thereon, the groove width is less than 0.06 wavelengths of the central operating frequency, and the side length of the rectangular metal patch is 0.08 wavelengths of the central operating frequency.

[0013] Furthermore, the SIW speaker cavity metallized vias 11 are two rows of metallized vias symmetrically distributed along the central axis.

[0014] Furthermore, the aperture of the metallized via 11 of the SIW speaker cavity is less than 0.1 wavelength of the center operating frequency; the minimum spacing between the centers of the two rows of metallized vias 11 of the SIW speaker cavity is greater than 0.2 wavelength of the center operating frequency and less than 0.4 wavelength of the center operating frequency; the maximum spacing between the centers of the two rows of metallized vias 11 of the SIW speaker cavity at the opening end of the speaker is less than 1 wavelength of the center operating frequency.

[0015] Furthermore, a row of radiation layer longitudinal metallized vias 12 are distributed on the central axis of the SIW speaker cavity metallized via 11 , penetrating the upper radiation layer metal plate 5 , the lower radiation layer metal plate 6 and the radiation layer dielectric substrate 2 .

[0016] Furthermore, a row of radiating layer transverse metallized vias 13 are distributed on both sides of the central axis of the SIW speaker cavity metallized via 11, penetrating the upper radiating layer metal plate 5, the lower radiating layer metal plate 6 and the radiating layer dielectric substrate 2; the radiating layer longitudinal metallized vias 12 and the radiating layer transverse metallized vias 13 are perpendicular to each other.

[0017] Furthermore, the apertures of the radiation layer longitudinal metallized via holes 12 and the radiation layer transverse metallized via holes 13 are smaller than 0.1 wavelength of the central operating frequency.

[0018] The beneficial effects of the millimeter wave SIW horn antenna loaded with EBG surface of the present invention are as follows:

[0019] The millimeter-wave SIW horn antenna loaded with an EBG surface of the present invention aims at the problems that the small-aperture matching of the traditional millimeter-wave H-plane SIW horn antenna is difficult and has a high back lobe level. While retaining the advantages of the SIW horn antenna such as low profile, simple structure, and easy integration, an EBG (Electromagnetic Band Gap) structure is loaded on the upper and lower surfaces of the antenna, so that most of the surface waves reflected at the junction of the horn aperture and the free space of the small-aperture millimeter-wave SIW horn antenna are mutually coupled and offset in the upper and lower EBG surfaces, thereby obtaining a lower antenna back lobe and a higher antenna gain; further, by adding a metallized via hole on the center line of the antenna aperture, the phase of the electromagnetic wave inside the horn and the reflected wave from the interface between the substrate and the free space are adjusted, thereby improving the gain. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 2 is a perspective view of an embodiment of the present invention.

[0021] Figure 2 It is an exploded view of each layer of an embodiment of the present invention.

[0022] Figure 3 2 is a top view of an embodiment of the present invention.

[0023] Figure 4 It is a left side view of an embodiment of the present invention.

[0024] Figure 5 It is a front view of an upper EBG metal layer and an upper EBG dielectric substrate according to an embodiment of the present invention.

[0025] Figure 6 4 is a front view of the upper radiation metal layer according to an embodiment of the present invention.

[0026] Figure 7 4 is a curve diagram showing how the reflection coefficient varies with the operating frequency according to an embodiment of the present invention.

[0027] Figure 8 It is the radiation pattern of the embodiment of the present invention at an operating frequency of 34 GHz.

[0028] Fig. 9 This is the radiation pattern of the embodiment of the present invention at an operating frequency of 35 GHz.

[0029] 1-upper EBG layer dielectric substrate; 2-radiation layer dielectric substrate; 3-lower EBG layer dielectric substrate; 4-upper EBG layer metal plate; 5-upper radiation layer metal plate; 6-lower radiation layer metal plate; 7-lower EBG layer metal plate; 8-feeding layer metal plate; 9-feeding layer metal ground; 401-EBG layer metal plate transverse groove; 402-EBG layer metal plate longitudinal groove; 403-rectangular metal patch; 10-EBG layer metalized via; 11-SIW speaker cavity metalized via; 12-radiation layer longitudinal metalized via; 13-radiation layer transverse metalized via. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with embodiments and with reference to the accompanying drawings.

[0031] Embodiment 1:

[0032] One embodiment of the present invention is a millimeter wave SIW horn antenna loaded with an EBG surface.

[0033] like Figure 1 to Figure 4As shown, the millimeter wave SIW horn antenna loaded with EBG surface in this embodiment includes: an upper EBG layer metal plate 4, an upper EBG layer dielectric substrate 1, an upper radiation layer metal plate 5, a radiation layer dielectric substrate 2, a lower radiation layer metal plate 6, a lower EBG layer dielectric substrate 3 and a lower EBG layer metal plate 7 which are pressed together in sequence. The feed layer metal plate 8 is coplanarly interconnected with the upper radiation layer metal plate 5, and the feed layer metal ground 9 is coplanarly interconnected with the lower radiation layer metal plate 6. The upper EBG layer dielectric substrate 1, the radiation layer dielectric substrate 2 and the lower EBG layer dielectric substrate 3 are all made of LTCC (Low Temperature Co-fired Ceramic) plates, and the plate thickness is less than 0.15 wavelengths of the central operating frequency (generally 0.2 to 0.7 mm). Preferably, the three-layer dielectric substrate uses an LTCC plate with a dielectric constant of 5.7. PTFE (polytetrafluoroethylene) microwave plates with a dielectric constant of 2.2 can also be used. The purpose of using a plate with a high dielectric constant as a dielectric substrate is to make the size of the millimeter wave SIW horn antenna loaded with the EBG surface smaller; under the same size, compared with the millimeter wave SIW horn antenna loaded with the EBG surface using a plate with a lower dielectric constant as the dielectric substrate, the millimeter wave SIW horn antenna made of a plate with a high dielectric constant can obtain a higher gain. The upper EBG layer metal plate 4, the upper radiation layer metal plate 5, the lower radiation layer metal plate 6, the lower EBG layer metal plate 7, the feed layer metal plate 8, and the feed layer metal ground 9 are made of metal, preferably a standard microwave copper clad plate with a thickness of 17 microns or 35 microns.

[0034] like Figure 5 As shown, the upper EBG layer metal plate 4 is divided into a patch array composed of rectangular metal patches 403 by the rectangular transverse grooves (i.e., the EBG layer metal plate transverse grooves 401) and rectangular longitudinal grooves (i.e., the EBG layer metal plate longitudinal grooves 402) etched thereon, wherein the groove width is less than 0.06 wavelengths of the center operating frequency, and the sides of the rectangular metal patches 403 are equal in length, which is about 0.08 wavelengths of the center operating frequency. The metallized vias 10 penetrate the upper EBG layer metal plate 4 and the upper EBG layer dielectric substrate 1 to form a via array. The center of the metallized via 10 should be consistent with the center of the corresponding rectangular metal patch 403. The lateral spacing between each metallized via 10 is less than 0.15 wavelengths of the center operating frequency, and the longitudinal spacing is less than 0.2 wavelengths of the center operating frequency. The aperture of the metallized via 10 should be less than 0.25 wavelengths of the center operating frequency. The lower EBG layer metal plate 7 has the same structure as the upper EBG layer metal plate 4 , and the lower EBG layer dielectric substrate 3 has the same structure as the upper EBG layer dielectric substrate 1 .

[0035] like Figure 6As shown, two rows of metallized vias 11 of the SIW horn cavity penetrate the upper radiation layer metal plate 5, the lower radiation layer metal plate 6 and the radiation layer dielectric substrate 2, starting from the lower end of the upper radiation layer metal plate 5 (the side interconnected with the feed layer metal plate 8), and gradually spread upward and symmetrically spread outward, that is, the two rows of metallized vias 11 of the SIW horn cavity are distributed in a horn shape, which is equivalent to a rectangular metal waveguide. The aperture of the metallized vias 11 of the SIW horn cavity should be less than 0.1 wavelength of the center working frequency, the long side of the equivalent rectangular metal waveguide (that is, the minimum distance between the centers of the metallized vias 11 of the two rows of SIW horn cavity) should be greater than 0.2 wavelength of the center working frequency and less than 0.4 wavelength of the center working frequency, and the SIW horn aperture (that is, the maximum distance between the centers of the two rows of metallized vias 11 of the SIW horn cavity at the horn opening end) should be less than 1 wavelength of the center working frequency. A row of longitudinal metallized vias 12 of the radiation layer is distributed on the central axis of the two rows of metallized vias 11 of the SIW horn cavity, penetrating the upper radiation layer metal plate 5, the lower radiation layer metal plate 6 and the radiation layer dielectric substrate 2. The function of the longitudinal metallized vias 12 of the radiation layer is to make the millimeter wave evenly distributed at the horn aperture. More preferably, a row of transverse metallized vias 13 of the radiation layer is also distributed on both sides of the central axis of the two rows of metallized vias 11 of the SIW horn cavity, penetrating the upper radiation layer metal plate 5, the lower radiation layer metal plate 6 and the radiation layer dielectric substrate 2. The longitudinal metallized vias 12 of the radiation layer and the transverse metallized vias 13 of the radiation layer are perpendicular to each other and can be arranged in a cross or in a T-shaped arrangement. The function is to adjust the phase of the internal electromagnetic wave and reflect the reflected wave from the interface between the dielectric substrate and the free space, so as to further improve the matching performance of the millimeter wave SIW horn antenna. In the absence of the longitudinal metallized vias 12 of the radiation layer and the transverse metallized vias 13 of the radiation layer, the amplitude and phase of the electromagnetic wave are uneven, thereby affecting the gain. The millimeter wave SIW horn antenna provided with the longitudinal metallized via hole 12 of the radiation layer and the transverse metallized via hole 13 of the radiation layer can further improve the gain compared with the millimeter wave SIW horn antenna with only the longitudinal metallized via hole 12 of the radiation layer. Ideally, the gain of the millimeter wave SIW horn antenna is maximum when the amplitude and phase of the incident wave and the reflected wave are the same. The aperture of the longitudinal metallized via hole 12 of the radiation layer and the transverse metallized via hole 13 of the radiation layer should be less than 0.1 wavelength of the center operating frequency.

[0036] like Figure 2As shown, the feed layer metal plate 8, the radiation layer dielectric substrate 2 and the feed layer metal ground 9 together constitute a microstrip transmission line structure (for example, a 50 ohm microstrip transmission line structure uniformly adopted in the industry), which is used for connecting the antenna with the back-end circuit. The electromagnetic wave is transmitted from the microstrip port on one side of the microstrip transmission line structure (i.e., the lower end of the feed layer metal plate 8) through the microstrip transmission line structure to the rectangular metal waveguide equivalent to the metallized via 11 of the SIW speaker cavity, and then radiates to the free space through the SIW speaker cavity. In the SIW speaker cavity, the longitudinal metallized via 12 of the radiation layer and the transverse metallized via 13 of the radiation layer adjust the wave velocity of the electromagnetic wave propagating in the forward direction. Because the impedance of the dielectric substrate does not match the impedance of the free space, the electromagnetic wave propagating in the forward direction is reflected at the junction of the speaker aperture and the free space. At the same time, most of the surface waves (for example, the reflected waves of the working frequency) reflected at the junction of the speaker aperture and the free space are mutually coupled and offset in the upper EBG surface. Similarly, they are also mutually coupled and offset in the lower EBG surface, thereby obtaining a lower antenna back lobe and a higher antenna gain. The upper and lower EBG surfaces are equivalent to filters that filter reflected waves of specific frequencies (such as operating frequency).

[0037] Taking the antenna design center operating frequency of 35GHz (wavelength 8.57mm) as an example, the simulation software can be used to obtain the specific size and material parameters of the millimeter wave SIW horn antenna loaded with EBG surface, so that it has a small diameter, high front-to-back ratio and high gain. Specifically, it can be:

[0038] The materials of the upper EBG layer dielectric substrate 1, the radiation layer dielectric substrate 2 and the lower EBG layer dielectric substrate 3 are all LTCC plates with a dielectric constant of 5.7. The thickness of the upper EBG layer dielectric substrate 1 and the lower EBG layer dielectric substrate 3 are both 0.7 mm, and the thickness of the radiation layer dielectric substrate 2 is 0.5 mm.

[0039] The thickness of the upper EBG layer metal plate 4, the upper radiation layer metal plate 5, the lower radiation layer metal plate 6, the lower EBG layer metal plate 7, the feed layer metal plate 8, and the feed layer metal ground 9 are all 35 um;

[0040] The size of the upper EBG layer dielectric substrate 1, the lower EBG layer dielectric substrate 3, the upper EBG layer metal plate 4 and the lower EBG layer metal plate 7 is 5.5mm×6.1mm; the size of the upper radiation layer metal plate 5 and the lower radiation layer metal plate 6 is 5.5mm×6.5mm, the size of the radiation layer dielectric substrate 2 is 5.5mm×8.5mm; the size of the feed layer metal plate 8 is 0.75mm×2mm; the size of the feed layer metal ground 9 is 4.5mm×2mm;

[0041] The width of the transverse groove 401 of the EBG layer metal plate is 0.42mm, and the width of the longitudinal groove 402 of the EBG layer metal plate is 0.34mm; the side length of the rectangular metal patch 403 is 0.66mm; the transverse spacing of the EBG layer metallized vias 10 is 1mm, and the longitudinal spacing is 1.1mm; the aperture of the SIW speaker cavity metallized via 11 is 0.3mm, the equivalent rectangular metal waveguide has a long side length of 2.2mm, and the maximum aperture of the speaker is 5mm; the aperture of the longitudinal metallized via 12 of the radiation layer is 0.2mm, and the aperture ratio is 0.5, and the aperture of the transverse metallized via 13 of the radiation layer is 0.2mm, and the aperture ratio is 0.67.

[0042] like Figure 7 As shown, the millimeter-wave SIW horn antenna loaded with an EBG surface provided in this embodiment has a reflection coefficient of less than -10dB and an impedance bandwidth of 5.7% within the operating frequency band of 33.8-35.8GHz; within the operating frequency band of 34.2-35.4GHz, the antenna is well matched with the transmission line, and the reflection coefficient of the antenna is basically lower than -20dB.

[0043] like Figure 8 As shown, the millimeter wave SIW horn antenna loaded with an EBG surface provided in this embodiment has an antenna gain of 5.5 dBi at a center operating frequency of 34 GHz, and the EBG surface effectively eliminates the backward radiation of the antenna. The antenna has a low back lobe characteristic and a front-to-back ratio of 16 dB.

[0044] like Fig. 9 As shown, the millimeter wave SIW horn antenna loaded with an EBG surface provided in this embodiment has an antenna gain of 5.5 dBi at a center operating frequency of 35 GHz, and the EBG surface effectively eliminates the backward radiation of the antenna. The antenna has a low back lobe characteristic and a front-to-back ratio of 16 dB.

[0045] The present invention is based on the improvement of the traditional SIW horn antenna and proposes a millimeter-wave high front-to-back ratio, high-gain small-aperture horn antenna structure based on EBG surface loading. While the aperture size is close to 0.6 wavelengths of the center operating frequency, a relative bandwidth of 5% is achieved, and the front-to-back ratio of the end-fire horn antenna is further improved, so that the antenna can be used in scanning arrays and also has the advantages of low profile, simple structure, easy processing and easy integration with active circuits.

[0046] Although the present invention has been disclosed as above with preferred embodiments, the embodiments are not intended to limit the present invention. Any equivalent changes or modifications made without departing from the spirit and scope of the present invention also belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the content defined by the claims of this application.

Claims

1. A millimeter wave SIW horn antenna loaded with an EBG surface, characterized in that: It comprises an upper EBG layer metal plate (4), an upper EBG layer dielectric substrate (1), an upper radiation layer metal plate (5), a radiation layer dielectric substrate (2), a lower radiation layer metal plate (6), a lower EBG layer dielectric substrate (3) and a lower EBG layer metal plate (7) which are pressed together in sequence, as well as a feed layer metal plate (8) interconnected coplanarly with the upper radiation layer metal plate (5), and a feed layer metal ground (9) interconnected coplanarly with the lower radiation layer metal plate (6); The upper EBG layer metal plate (4) is divided into a rectangular metal patch array by rectangular transverse grooves and rectangular longitudinal grooves etched thereon, the groove width is less than 0.06 wavelengths of the central operating frequency, and the side length of the rectangular metal patch is 0.08 wavelengths of the central operating frequency; the metallized via hole (10) penetrates the upper EBG layer metal plate (4) and the upper EBG layer dielectric substrate (1) to form a via hole array, and the center of the metallized via hole (10) is consistent with the center of the corresponding metal patch; The lower EBG layer metal plate (7) has the same structure as the upper EBG layer metal plate (4), and the lower EBG layer dielectric substrate (3) has the same structure as the upper EBG layer dielectric substrate (1); Two rows of a plurality of SIW horn cavity metallized vias (11) symmetrically distributed along the central axis penetrate the upper radiation layer metal plate (5), the lower radiation layer metal plate (6) and the radiation layer dielectric substrate (2), and are symmetrically spread out gradually from the side of the upper radiation layer metal plate (5) interconnected with the feed layer metal plate (8) toward the other side of the upper radiation layer metal plate (5) toward both outer sides, equivalent to a rectangular metal waveguide; the aperture of the SIW horn cavity metallized vias (11) is less than 0.1 wavelength of the center operating frequency; the minimum spacing between the centers of the two rows of SIW horn cavity metallized vias (11) is greater than 0.2 wavelength of the center operating frequency and less than 0.4 wavelength of the center operating frequency; the maximum spacing between the centers of the two rows of SIW horn cavity metallized vias (11) at the horn opening end is less than 1 wavelength of the center operating frequency; A row of radiation layer longitudinal metallized via holes (12) are distributed on the central axis of the SIW speaker cavity metallized via hole (11), penetrating the upper radiation layer metal plate (5), the lower radiation layer metal plate (6) and the radiation layer dielectric substrate (2); A row of lateral radiation layer metallized via holes (13) are also distributed on both sides of the central axis of the SIW speaker cavity metallized via hole (11), penetrating the upper radiation layer metal plate (5), the lower radiation layer metal plate (6) and the radiation layer dielectric substrate (2); The radiation layer longitudinal metallized via holes (12) and the radiation layer transverse metallized via holes (13) are perpendicular to each other; The apertures of the radiation layer longitudinal metallized via holes (12) and the radiation layer transverse metallized via holes (13) are smaller than 0.1 wavelength of the central operating frequency.

2. The millimeter wave SIW horn antenna loaded with an EBG surface according to claim 1, characterized in that: The upper EBG layer dielectric substrate (1), the radiation layer dielectric substrate (2), and the lower EBG layer dielectric substrate (3) are all made of LTCC plates or PTFE microwave plates.

3. The millimeter wave SIW horn antenna loaded with an EBG surface according to claim 1, characterized in that: The metal patch array is composed of rectangular metal patches.

4. The millimeter wave SIW horn antenna loaded with an EBG surface according to claim 3, characterized in that: The sides of the rectangular metal patches are equal in length.

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