A substrate integrated waveguide filter antenna

Abstract

The invention relates to a substrate integrated waveguide filtering antenna, comprising: an upper dielectric substrate, an upper metal grounding plate, a middle dielectric substrate, a middle metal grounding plate, a lower dielectric substrate and a lower metal grounding plate which are stacked in sequence, forming an antenna part and a filter part; two rectangular radiation slots are etched on the upper metal grounding plate, and a radiation unit is coupled with the filter part through the two rectangular radiation slots; two rectangular coupling slots are etched near the two ends of the middle metal grounding plate, and a square coupling slot with coupling branches is etched at the center, and an upper resonant cavity and a lower resonant cavity of the filter part are coupled through the rectangular coupling slot and the square coupling slot with coupling branches; an excitation source is arranged on the lower metal grounding plate, and electromagnetic waves generated by the excitation source are first propagated to the filter part through the rectangular coupling slot on the middle metal grounding plate, and then propagated to the metal patch through the rectangular radiation slot on the upper metal grounding plate and radiated out.

Description

Technical Field

[0001] The invention relates to the technical field of communication antennas, and in particular to a substrate integrated waveguide filtering antenna. Background Art

[0002] Influenced by the rapid development of wireless communication technology, miniaturization, lightweight, and high integration have become important features of modern RF circuits, and the space resources of RF front-end circuits have been compressed. The antenna and the filter need to be connected across multiple devices, which has high circuit complexity and space cost. Therefore, the integrated design of antenna and filter with low cost, high integration, and low loss characteristics has attracted widespread attention. The design of filter antennas with good radiation performance and out-of-band suppression function has become the focus of research.

[0003] Especially in satellite communication phased array antennas, the antenna part usually uses a microstrip patch antenna as a radiating antenna, and uses multi-layer board vertical interconnection technology and RF chip connection. Vertically interconnecting the filter and the antenna can reduce the design complexity of the RF chip and reduce costs. Therefore, the filter antenna is very suitable for the field of satellite communication phased array antenna technology.

[0004] However, the filters in existing filtering antennas usually use cross-coupling and electromagnetic hybrid coupling to improve the passband selectivity of the filter. During the design, more resonant cavities need to be used, which makes the overall size too large. Without changing the original size, it is impossible to enhance the frequency selectivity of the upper and lower band edges, and it is impossible to obtain a wider impedance bandwidth. Summary of the invention

[0005] To this end, the technical problem to be solved by the present invention is to overcome the problem in the prior art that the overall size of the filtering antenna is increased when the filtering antenna uses more resonant cavities to enhance the passband selectivity of the filter, and to provide a substrate integrated waveguide filtering antenna that generates radiation zero points at the upper and lower band edges without changing the number of resonant cavities, thereby enhancing the frequency selectivity of the upper and lower band edges, so that the filtering antenna has a wider impedance bandwidth, good out-of-band suppression capability and flat passband gain, and is applied in complex electromagnetic signal environments.

[0006] In order to solve the above technical problems, the present invention provides a substrate integrated waveguide filter antenna, comprising: an upper dielectric substrate, an upper metal ground plate, a middle dielectric substrate, a middle metal ground plate, a lower dielectric substrate and a lower metal ground plate stacked in sequence, wherein:

[0007] A metal patch is arranged on the upper surface of the upper dielectric substrate as a radiation unit to form an antenna part;

[0008] The middle dielectric substrate is provided with an upper metal through hole penetrating the middle dielectric substrate, and the upper metal through hole, the middle dielectric substrate and the upper metal ground plate together constitute an upper resonant cavity;

[0009] The lower dielectric substrate is provided with a lower metal through hole penetrating the lower dielectric substrate. The lower metal through hole, the lower dielectric substrate and the middle metal ground plate together constitute a lower resonant cavity. The upper resonant cavity and the lower resonant cavity constitute a filter part.

[0010] Two rectangular radiation slots are etched on the upper metal ground plate, and the radiation unit is coupled with the filter part through the two rectangular radiation slots;

[0011] Two rectangular coupling grooves are etched near the two ends of the middle metal ground plate. When the upper resonant cavity and the lower resonant cavity are coupled, the two rectangular coupling grooves can enhance the magnetic coupling, so that the upper resonant cavity and the lower resonant cavity are directly coupled, and a transmission zero point can be generated. This is the first coupling path; a square coupling groove with a coupling branch is etched at the center to form a resonator structure. The upper and lower resonant cavities can be coupled with the coupling branch. This is the second coupling path and can also generate a transmission zero point. The two coupling paths can be used to generate transmission zero points at the upper and lower band edges respectively, which can enhance the frequency selectivity of the upper and lower band edges.

[0012] An excitation source is arranged on the lower metal grounding plate. The electromagnetic wave generated by the excitation source is first propagated to the filter part through the rectangular coupling slot and the square coupling slot on the middle metal grounding plate, and then propagated to the metal patch through the rectangular radiation slot on the upper metal grounding plate and radiated out.

[0013] In one embodiment of the present invention, the upper metal vias are linearly distributed around the middle dielectric substrate, and the lower metal vias are linearly distributed around the middle dielectric substrate, and the positions of the upper metal vias and the lower metal vias correspond one to one.

[0014] In one embodiment of the present invention, the upper metal through hole and the lower metal through hole have the same height, and the upper resonant cavity and the lower resonant cavity have the same thickness.

[0015] In one embodiment of the present invention, the two rectangular radiation slots have different sizes.

[0016] In one embodiment of the present invention, the two rectangular coupling slots have the same size.

[0017] In one embodiment of the present invention, the distance between the two rectangular coupling slots and the square coupling slot is the same.

[0018] In one embodiment of the present invention, the two rectangular coupling slots are arranged in mirror symmetry with respect to the center of the upper resonant cavity and the lower resonant cavity.

[0019] In one embodiment of the present invention, the coupling branches are distributed in the square coupling slots in a serpentine shape.

[0020] In one embodiment of the present invention, the excitation source includes: a 50-ohm microstrip line, a coplanar waveguide feed line, and two rectangular matching grooves etched on a lower metal ground plane and symmetrical about the center of the coplanar waveguide feed line.

[0021] In one embodiment of the present invention, the upper dielectric substrate, the middle dielectric substrate, and the lower dielectric substrate are made of the same material and have the same dielectric constant and loss tangent value.

[0022] The above technical solution of the present invention has the following advantages compared with the prior art:

[0023] The substrate integrated waveguide filter antenna described in the present invention adopts a filter part composed of two vertically interconnected resonant cavities, wherein the upper and lower resonant cavities are coupled through a rectangular coupling slot on the middle metal layer and a square coupling slot with coupling branches, so that the structure of the entire filter antenna is more compact and suitable for the field of millimeter wave systems, and the coupling branches can increase the order of the filter and generate controllable transmission zero points, thereby improving the frequency selectivity of the filter; the antenna part adopts a metal patch as a radiation unit, and is coupled with the lower filter antenna through two rectangular radiation slots on the upper metal grounding plate, and the electromagnetic wave generated by the excitation source is first propagated to the filter part through the coupling slot on the middle metal grounding plate, and then propagated to the microstrip patch through the coupling slot on the upper metal grounding plate and radiated out.

[0024] By using the substrate integrated waveguide filter antenna described in the present invention, it is possible to improve the passband selectivity of the filter without increasing the number of existing resonant cavities, so that the filter antenna has a wider impedance bandwidth, good out-of-band suppression capability and flat passband gain, and can be used in complex electromagnetic signal environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 It is a schematic diagram of the overall structure of the substrate integrated waveguide filter antenna of the present invention;

[0027] Figure 2 is a top view of the upper metal ground plate of the present invention;

[0028] Figure 3 is a top view of the middle metal ground plate of the present invention;

[0029] Figure 4 is a top view of the lower metal ground plate of the present invention;

[0030] Figure 5 The S-parameters and achievable gain curve of the substrate integrated waveguide filter antenna of the present invention;

[0031] Figure 6 The E-plane radiation pattern of the filtering antenna of the present invention at the center frequency;

[0032] Figure 7 It is the H-plane radiation pattern of the filtering antenna of the present invention at the center frequency.

[0033] Explanation of the markings in the specification: 1. upper dielectric substrate; 2. middle dielectric substrate; 3. lower dielectric substrate; 4. upper metal ground plate; 5. middle metal ground plate; 6. lower metal ground plate; 7. upper metal through-hole; 8. lower metal through-hole; 9. metal patch; 10. first rectangular radiation slot; 11. second rectangular radiation slot; 12. first rectangular coupling slot; 13. second rectangular coupling slot; 14. square coupling slot; 15. coupling branch; 16. 50 ohm microstrip line; 17. coplanar waveguide feed line; 18. rectangular matching slot. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0035] Reference Figure 1 As shown, the present invention discloses a substrate integrated waveguide filter antenna, comprising: an upper dielectric substrate 1, an upper metal ground plate 4, a middle dielectric substrate 2, a middle metal ground plate 5, a lower dielectric substrate 3 and a lower metal ground plate 6 which are stacked in sequence, and these structures can form an antenna part and a filter part, wherein:

[0036] A metal patch 9 is provided on the upper surface of the upper dielectric substrate 1 as a radiation unit to form an antenna part;

[0037] The middle dielectric substrate 2 is provided with an upper metal through hole 7 penetrating the middle dielectric substrate 2, and the upper metal through hole 7 is linearly distributed around the middle dielectric substrate 2. The upper metal through hole 7, the middle dielectric substrate 2 and the upper metal grounding plate 4 together constitute an upper resonant cavity, and the upper metal through hole 7 constitutes a metal wall of the upper resonant cavity; the lower dielectric substrate 3 is provided with a lower metal through hole 8 penetrating the middle dielectric substrate 2, and the lower metal through hole 8, the lower dielectric substrate 3 and the middle metal grounding plate 5 together constitute a lower resonant cavity, and the lower metal through hole 8 constitutes a metal wall of the lower resonant cavity, and the positions of the upper metal through hole 7 and the lower metal through hole 8 are arranged one by one to vertically interconnect and closely fit the two resonant cavities, and through the coupling of the upper resonant cavity and the lower resonant cavity, the structure has the function of a filter, so that the upper resonant cavity and the lower resonant cavity constitute a filter part.

[0038] As described in the background technology, in the prior art, in order to improve the passband selectivity of the filter, cross coupling and electromagnetic hybrid coupling are usually used, which means that more resonant cavities need to be added. The inventor wants to improve the passband characteristics of the filter without changing the resonant cavity, so it is necessary to add a new coupling path. To this end, the inventor has made the following improvements on the substrate integrated waveguide filter antenna of this embodiment:

[0039] Reference Figure 2 As shown, two rectangular radiation slots are etched on the upper metal ground plate 4, namely a first rectangular radiation slot 10 and a second rectangular radiation slot 11. The radiation unit is coupled with the filter part through the two rectangular radiation slots. The rectangular radiation slots, as coupling slots, can propagate electromagnetic waves to the metal patch 9 and radiate them out, thereby realizing the combination of the filter part and the antenna part. In order to realize the coupling between the antenna part and the filter part, different sizes of the two rectangular radiation slots are set during the actual design.

[0040] Reference Figure 3As shown, two rectangular coupling grooves, namely a first rectangular coupling groove 12 and a second rectangular coupling groove 13, are etched near the two ends of the middle metal ground plate 5. When the upper resonant cavity and the lower resonant cavity are coupled, the two rectangular coupling grooves can enhance the magnetic coupling, so that the upper resonant cavity and the lower resonant cavity are directly coupled, and a transmission zero point can be generated, which is the first coupling path; a square coupling groove 14 with a coupling branch 15 is etched at the center to form a resonator structure, and the upper and lower resonant cavities can be coupled with the coupling branch, which is the second coupling path, and a transmission zero point can also be generated; when the upper resonant cavity and the lower resonant cavity are coupled by the structure of this embodiment, the upper and lower resonant cavities can be coupled with the coupling branch 15, and can also be directly coupled, so there are two coupling paths, and the two coupling paths can be used to generate radiation zero points at the upper and lower band edges respectively, enhance the frequency selectivity of the upper and lower band edges, thereby increasing the order of the filter, so that without increasing the number of resonant cavities, the passband selectivity of the filter can be improved, so that the filtering antenna has a wider impedance bandwidth, good out-of-band suppression capability and flat passband gain, and can be applied to complex electromagnetic signal environments.

[0041] Reference Figure 4 As shown, an excitation source is arranged on the lower metal grounding plate 6. The electromagnetic wave generated by the excitation source is first propagated to the filter part through the rectangular coupling slot and the square coupling slot 14 on the middle metal grounding plate 5, and then propagated to the metal patch 9 through the rectangular radiation gap on the upper metal grounding plate 4 and radiated out.

[0042] Specifically, in this embodiment, in order to ensure the stability of the coupling between the upper and lower resonators, the upper metal through hole 7 and the lower metal through hole 8 are set to have the same height, and the upper resonant cavity and the lower resonant cavity are set to have the same thickness.

[0043] Specifically, in order to ensure the stability of the coupling between the upper and lower resonators, the two rectangular coupling slots have the same size, the two rectangular coupling slots are at the same distance from the square coupling slot 14, and the two rectangular coupling slots are arranged in mirror symmetry with respect to the center of the upper resonant cavity and the lower resonant cavity.

[0044] Specifically, the coupling branches 15 are distributed in the square coupling slots 14 in a serpentine shape.

[0045] In this embodiment, the excitation source includes: a 50-ohm microstrip line 16, a coplanar waveguide feed line 17, and two rectangular matching slots 18 etched on the lower metal ground plane 6 and symmetrical about the center of the coplanar waveguide feed line 17. In other embodiments, other forms of excitation sources may also be used.

[0046] Specifically, the upper dielectric substrate 1 , the middle dielectric substrate 2 , and the lower dielectric substrate 3 are made of the same material and have the same dielectric constant and loss tangent value.

[0047] In order to further verify the feasibility of the substrate integrated waveguide filter antenna of this embodiment and to achieve the above-mentioned beneficial effects, the substrate integrated waveguide filter antenna is prepared and verified according to the contents recorded in the above-mentioned specification. The parameters of the prepared substrate integrated waveguide filter antenna are as follows:

[0048] The upper dielectric substrate 1, the middle dielectric substrate 2, and the lower dielectric substrate 3 are vertically interconnected, stacked and laminated. The materials of the upper dielectric substrate 1, the middle dielectric substrate 2, and the lower dielectric substrate 3 are all Rogers Duroid 5880, which has a relative dielectric constant of 2.2 and a loss tangent of 0.0009. The sizes of the upper dielectric substrate 1, the middle dielectric substrate 2, and the lower dielectric substrate 3 are 49 mm×37 mm, the thickness of the upper dielectric substrate 1 is 2 mm, and the thicknesses of the middle dielectric substrate 2 and the lower dielectric substrate 3 are both 0.7 mm.

[0049] The upper metal ground plate 4, the middle metal ground plate 5, the lower metal ground plate 6, the metal patch 9, and the 50 ohm microstrip line 16 are all made of metal copper material, and the metal thickness used is the same, both 0.018 mm. The upper metal ground plate 4 and the middle metal ground plate 5 correspond to the upper dielectric substrate 1 and the middle dielectric substrate 2, and have a size of 49 mm × 37 mm. The size of the lower metal ground plate 66 is 33 mm × 33 mm. The upper metal through hole 7 and the lower metal through hole 8 serve as the metal walls of the upper and lower resonant cavities. The radius of the metal through hole is 0.5 mm, and the center spacing of the metal through holes is 2 mm.

[0050] Reference Figure 2 As shown, the first rectangular radiation slot 10 and the second rectangular radiation slot 11 are etched on the upper metal grounding plate 4, wherein: the size of the first rectangular radiation slot 10 is 27mm×4mm, the size of the second rectangular radiation slot 11 is 20mm×1mm, and the distance L1 between the first rectangular radiation slot 10 and the left edge of the upper metal grounding plate 4 is set to 20mm, the distance L2 between the first rectangular radiation slot 10 and the second rectangular radiation slot 11 is set to 11mm, and the size of the metal patch 9 is set to 25mm×15mm, and the first rectangular radiation slot 10 and the second rectangular radiation slot 11 and the metal patch 9 together play the role of radiating electromagnetic waves into the free space.

[0051] Reference Figure 3As shown, the middle metal grounding plate 5 is etched with a first rectangular coupling groove 12 and a second rectangular coupling groove 13 near the two ends, the sizes of the first rectangular coupling groove 12 and the second rectangular coupling groove 13 are both 7mm×0.5mm, and the two rectangular coupling grooves are mirror-symmetrical about the center of the resonant cavity. A 4mm×4mm square coupling groove 14 is etched at the center of the upper and lower resonant cavities of the middle metal grounding plate 5, and a coupling branch 15 with a length of 14mm is added to the side wall of the square coupling groove 14 to generate radiation zero points at the upper and lower band edges, respectively, to enhance the frequency selectivity of the upper and lower band edges. Specifically, the distance L3 between the first rectangular coupling groove 12 and the left edge of the middle metal grounding plate 5 is set to 21mm, the distance L4 between the first rectangular coupling groove 12 and the first rectangular coupling groove 12 and the square coupling groove 14 is set to 8mm, and the distance L5 between the first rectangular coupling groove 12 and the rear edge of the middle metal grounding plate 5 is set to 10mm.

[0052] Reference Figure 4 As shown, the 50 ohm microstrip line 16 has a length of 14 mm and a width of 3 mm, the coplanar waveguide feed line 17 has a length of 7 mm and a width of 3 mm, and the rectangular matching slot 18 has a length of 7 mm and a width of 2 mm.

[0053] After completing the above initial design, the reflection coefficient and passband gain of the filter antenna are simulated and analyzed using the high-frequency electromagnetic simulation software HFSS. Figure 5 To simulate the S parameter diagram and gain variation with frequency of the filtering antenna in this embodiment, within the passband, the impedance bandwidth below -10dB exceeds 12% (4.45GHz-5.0GHz), with a flat gain within the passband, and the gain outside the passband is suppressed to about -20dB, with good out-of-band suppression effect. Figure 6 and Figure 7 They are respectively the E-plane and H-plane radiation patterns of the filtering antenna of the present invention at 4.9 GHz. It can be seen that the radiation pattern of the filtering antenna is symmetrical, has good radiation characteristics, and can achieve a gain peak of 5.35 dB.

[0054] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A substrate integrated waveguide filter antenna, characterized in that: include: An upper dielectric substrate, an upper metal grounding plate, a middle dielectric substrate, a middle metal grounding plate, a lower dielectric substrate and a lower metal grounding plate are stacked in sequence, wherein: A metal patch is arranged on the upper surface of the upper dielectric substrate as a radiation unit to form an antenna part; The middle dielectric substrate is provided with an upper metal through hole penetrating the middle dielectric substrate, and the upper metal through hole, the middle dielectric substrate and the upper metal ground plate together constitute an upper resonant cavity; The lower dielectric substrate is provided with a lower metal through hole penetrating the lower dielectric substrate, the lower metal through hole, the lower dielectric substrate and the middle metal ground plate together constitute a lower resonant cavity, and the upper resonant cavity and the lower resonant cavity constitute a filter part; Two rectangular radiation slots are etched on the upper metal ground plate, and the radiation unit is coupled with the filter part through the two rectangular radiation slots; Two rectangular coupling grooves are etched near the two ends of the middle metal ground plate. When the upper resonant cavity and the lower resonant cavity are coupled, the two rectangular coupling grooves can enhance the magnetic coupling, so that the upper resonant cavity and the lower resonant cavity are directly coupled, and a transmission zero point can be generated. This is the first coupling path; a square coupling groove with a coupling branch is etched at the center to form a resonator structure. The upper and lower resonant cavities are coupled with the coupling branch. This is the second coupling path, which can also generate a transmission zero point. The two coupling paths can be used to generate transmission zero points at the upper and lower band edges respectively, which can enhance the frequency selectivity of the upper and lower band edges. An excitation source is arranged on the lower metal grounding plate. The electromagnetic wave generated by the excitation source is first propagated to the filter part through the rectangular coupling slot and the square coupling slot on the middle metal grounding plate, and then propagated to the metal patch through the rectangular radiation slot on the upper metal grounding plate and radiated out.

2. The substrate integrated waveguide filter antenna according to claim 1, characterized in that: The upper metal through holes are linearly distributed around the middle dielectric substrate, and the lower metal through holes are linearly distributed around the middle dielectric substrate. The positions of the upper metal through holes and the lower metal through holes correspond to each other.

3. The substrate integrated waveguide filter antenna according to claim 1, characterized in that: The upper metal through hole and the lower metal through hole have the same height, and the upper resonant cavity and the lower resonant cavity have the same thickness.

4. The substrate integrated waveguide filter antenna according to claim 1, characterized in that: The two rectangular radiation slots have different sizes.

5. The substrate integrated waveguide filter antenna according to claim 1, characterized in that: The two rectangular coupling slots have the same size.

6. The substrate integrated waveguide filter antenna according to claim 1, characterized in that: The distances between the two rectangular coupling slots and the square coupling slot are the same.

7. The substrate integrated waveguide filter antenna according to claim 1, characterized in that: The two rectangular coupling slots are arranged in mirror symmetry with respect to the centers of the upper resonant cavity and the lower resonant cavity.

8. The substrate integrated waveguide filter antenna according to claim 1, characterized in that: The coupling branches are distributed in the square coupling grooves in a serpentine shape.

9. The substrate integrated waveguide filter antenna according to claim 1, characterized in that: The excitation source includes: a 50-ohm microstrip line, a coplanar waveguide feed line, and two rectangular matching grooves etched on a lower metal ground plate and symmetrically about the center of the coplanar waveguide feed line.

10. The substrate integrated waveguide filter antenna according to claim 1, characterized in that: The upper dielectric substrate, the middle dielectric substrate and the lower dielectric substrate are made of the same material and have the same dielectric constant and loss tangent value.

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