Low-loss compact filter for broadband satellite communication

Abstract

The invention discloses a low-loss compact filter for broadband satellite communication, which relates to the technical field of microwaves and comprises a top metal layer, a middle metal layer, a bottom metal layer, an upper dielectric substrate, a lower dielectric substrate, a bonding layer, a metal short groove and a metalized through hole structure, the upper layer dielectric substrate and the lower layer dielectric substrate are bonded through a bonding layer. According to the low-loss compact filter for broadband satellite communication, the folded substrate integrated waveguide resonant cavity of a double-layer coupling structure is adopted, so that the aim of miniaturization of the filter is achieved. The equivalent metal waveguide is formed by using the eight hollow metal short grooves and the four discrete metalized through holes, the number of metalized through holes is reduced, the structure is simple, the machining difficulty is low, and manufacturing is convenient. In addition, the rectangular grooves are etched in the top metal layer and the bottom metal layer to serve as input and output ports, traditional transition structures such as micro-strips are prevented from being used for connection, and therefore the filter has the low-loss characteristic.

Description

Technical Field

[0001] The invention relates to the field of microwave technology, in particular to a low-loss compact filter for broadband satellite communications. Background Art

[0002] With the rapid development of wireless communication technology, broadband satellite communication equipment is becoming more and more integrated and thinner. The miniaturization, high performance, low cost and high integration of electronic products have gradually become an inevitable trend. Filters are key components of wireless communication systems. High-performance filters can effectively filter out clutter outside the channel frequency and enhance the performance of the communication system.

[0003] The existing technology designs RF front-end filters based on metal waveguides, coaxial lines and strip lines. For transmit filtering, metal waveguides have the advantages of low loss, high Q value, high power capacity and strong mechanical structure, but they also have the disadvantages of large size and weight, difficult processing and debugging, and not conducive to the miniaturization and high integration of equipment; strip lines are small in size and flexible in layout, but their open structure introduces large radiation and leakage losses, and the resonator has a low Q value, which is not suitable for high frequency bands, especially in the millimeter wave band; the coaxial line structure has a high Q value and high power capacity, but its size in the millimeter wave band is too small, and the existing processing level is not easy to meet the demand, and it is difficult to integrate with planar circuits. Therefore, the design of millimeter wave broadband satellite communication transmit filters based on traditional filter technology can no longer fully meet the requirements of technological development, so a low-loss compact filter for broadband satellite communications is proposed. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a low-loss compact filter for broadband satellite communications, which solves the problems raised in the above-mentioned background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a low-loss compact filter for broadband satellite communication, comprising a top metal layer, an intermediate metal layer, a bottom metal layer, an upper dielectric substrate, a lower dielectric substrate, an adhesive layer, a metal short groove and a metalized through-hole structure, wherein the upper dielectric substrate and the lower dielectric substrate are bonded to each other through an adhesive layer, the upper surface of the upper dielectric substrate is coated with a top metal layer, the lower surface of the upper dielectric substrate is coated with an intermediate metal layer, the upper surface of the lower dielectric substrate is coated with an adhesive layer, and the lower surface of the lower dielectric substrate is coated with a bottom metal layer, and the low-loss compact filter is formed by stacking the top metal layer, the upper dielectric substrate, the intermediate metal layer, the adhesive layer, the lower dielectric substrate and the bottom metal layer.

[0006] Optionally, eight hollow metal short grooves are arranged on the upper dielectric substrate, the adhesive layer and the lower dielectric substrate.

[0007] Optionally, the metallized through hole structure includes a first metallized through hole, a second metallized through hole and a third metallized through hole, and four first metallized through holes located at opposite corners and discrete second metallized through holes are provided on the upper dielectric substrate, the adhesive layer and the lower dielectric substrate.

[0008] Optionally, the hollow metal short slot and the metallized through-hole structure are connected to the top metal layer, the upper dielectric substrate, the middle metal layer, the adhesive layer, the lower dielectric substrate and the bottom metal layer.

[0009] Optionally, the eight hollow metal short slots and the first metallized through hole form a first resonant cavity, a second resonant cavity and a third resonant cavity, the first resonant cavity and the second resonant cavity, and the second resonant cavity and the third resonant cavity are connected through a common metallized through hole wall, and the common metallized through hole structure uses discrete metal vias to form an inductor film hole, that is, a part of the metallized through hole is missing on the common metallized through hole wall to form a magnetic coupling window. A group of peripherally closed third metallized through holes are arranged on the upper dielectric substrate, the adhesive layer and the lower dielectric substrate, and the peripherally closed third metallized through holes are located outside the hollow metal short slots and are spaced a certain distance apart to prevent electromagnetic energy from leaking from the gaps of the short slots around the resonant cavity.

[0010] Optionally, a top-layer rectangular groove is provided on the top metal layer, an intermediate-layer rectangular groove is provided on the intermediate metal layer, and a bottom-layer rectangular groove is provided on the bottom metal layer. The relative positions and sizes of the top-layer rectangular groove and the bottom-layer rectangular groove are the same. The top-layer rectangular groove serves as an input port connected to the first resonant cavity, and the bottom-layer rectangular groove serves as an output port connected to the third resonant cavity, and is used to connect waveguide feeding or connect external satellite communication equipment.

[0011] Optionally, the second resonant cavity is symmetrically distributed above and below the middle metal layer, and energy coupling between the upper and lower layers is achieved by etching a rectangular long groove on the middle metal layer.

[0012] The present invention provides a low-loss compact filter for broadband satellite communications, which has the following beneficial effects:

[0013] This low-loss compact filter for broadband satellite communications uses a double-layer coupled structure of folded substrate integrated waveguide resonator to achieve the goal of miniaturization of the filter. By using eight hollow metal short slots and four discrete metallized through holes to form an equivalent metal waveguide, the number of metallized through holes is reduced, the structure is simple, the processing difficulty is low, and the manufacturing is convenient. In addition, by etching rectangular slots on the top and bottom metal layers as input and output ports, the use of traditional transition structures such as microstrip for connection is avoided, so that this filter has low loss characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1Schematic diagram of the three-dimensional structure of the folded SIW filter in an embodiment of the present invention;

[0015] Figure 2 For the present invention Figure 1 Schematic diagram of the three-dimensional sectioning of the multi-layer PCB structure;

[0016] Figure 3 is a top view of the structure of a folded SIW filter in an embodiment of the present invention;

[0017] Figure 4 Graph showing simulation results of the S parameter amplitude of the waveguide-fed folded SIW filter in an embodiment of the present invention.

[0018] In the figure: 110, top metal layer; 120, upper dielectric substrate; 130, middle metal layer; 140, bonding layer; 150, lower dielectric substrate; 160, bottom metal layer; 170, hollow metal short groove; 180, metallized through hole structure; 1801, first metallized through hole; 1802, second metallized through hole; 1803, third metallized through hole; 190, inductor film hole; 200, top rectangular groove; 210, bottom rectangular groove; 220, middle rectangular groove. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0020] See also Figures 1 to 4 The present invention provides a technical solution: a low-loss compact filter for broadband satellite communication, comprising a top metal layer 110, an intermediate metal layer 130, a bottom metal layer 160, an upper dielectric substrate 120, a lower dielectric substrate 150, an adhesive layer 140, a hollow metal short groove 170 and a metallized through-hole structure 180, wherein the upper dielectric substrate 120 and the lower dielectric substrate 150 are bonded to each other through the adhesive layer 140, the top metal layer 110 is applied on the upper surface of the upper dielectric substrate 120, the intermediate metal layer 130 is applied on the lower surface of the upper dielectric substrate 120, the adhesive layer 140 is applied on the upper surface of the lower dielectric substrate 150, and the bottom metal layer 160 is applied on the lower surface of the lower dielectric substrate 150, and the low-loss compact filter is formed by stacking the top metal layer 110, the upper dielectric substrate 120, the intermediate metal layer 130, the adhesive layer 140, the lower dielectric substrate 150 and the bottom metal layer 160.

[0021] Table 1

[0022]

[0023] like Figure 1-Figure 3As shown, the filter adopts a folded substrate integrated waveguide resonant cavity with a double-layer coupling structure to achieve the goal of miniaturization of the filter;

[0024] The filter is layered into three metal layers, two dielectric layers and one adhesive layer. A top metal layer 110, an upper dielectric substrate 120, an intermediate metal layer 130, an adhesive layer 140, a lower dielectric substrate 150 and a bottom metal layer 160 are stacked in sequence from top to bottom along the longitudinal z-axis.

[0025] In this embodiment, the top metal layer 110 is a rectangular metal sheet covering the entire upper surface of the upper dielectric substrate 120. Similarly, the bottom metal layer 160 is a rectangular metal sheet covering the entire lower surface of the lower dielectric substrate 150. The middle metal layer 130 is a signal layer metal surface.

[0026] Eight hollow metal short slots 170 and metallized through holes 180 are provided on the upper dielectric substrate 120, the adhesive layer 140 and the lower dielectric substrate 150. The hollow metal short slots 170 and the first metallized through holes 1801 are connected to the top metal layer 110, the upper dielectric substrate 120, the middle metal layer 130, the adhesive layer 140, the lower dielectric substrate 150 and the bottom metal layer 160 to form the first resonant cavity, the second resonant cavity and the third resonant cavity in sequence. The first resonant cavity and the second resonant cavity, and the second resonant cavity and the third resonant cavity are connected through a common metallized through hole wall, and the common metallized through hole wall uses a discrete second metallized through hole 1802 to form an inductor film hole 190, that is, a part of the metallized through hole is missing on the common metallized through hole wall to form a magnetic coupling window. The coupling coefficient between the first resonant cavity and the second resonant cavity, and between the second resonant cavity and the third resonant cavity of the filter can be adjusted by adjusting the length of the inductor film hole 190.

[0027] The top metal layer 110 is provided with a top rectangular groove 200, and the bottom metal layer 160 is provided with a bottom rectangular groove 210, which are respectively used as the input and output ports of the filter of the embodiment of the present invention, and are used for connection and integration with other external satellite communication equipment. By adjusting the length and width of the top rectangular groove 200 and the bottom rectangular groove 210, the external coupling coefficient of the filter can be adjusted. By adjusting the relative position of the top rectangular groove 200 and the bottom rectangular groove 210 to the hollow metal short groove 170, the out-of-band suppression on both sides of the passband of the filter can be adjusted.

[0028] The second resonant cavity is symmetrically distributed up and down according to the intermediate metal layer 130, with half of the cavity located in the upper dielectric substrate 120 and half of the cavity located in the lower dielectric substrate 150, and the inter-cavity coupling of the upper and lower layers is achieved through the gap intermediate layer rectangular groove 220 etched on the intermediate metal layer 130. The electric field of the resonant cavity is strongest along the gap intermediate layer rectangular groove 220.

[0029] Furthermore, a group of peripherally enclosed third metallized through holes 1803 are provided on the upper dielectric substrate 120, the adhesive layer 140 and the lower dielectric substrate 150. The peripherally enclosed third metallized through holes 1803 are located outside the above-mentioned hollow metal short grooves 170 and are spaced a certain distance apart to prevent the strong electromagnetic energy at the middle layer rectangular groove 220 from leaking from the gaps of the surrounding short grooves.

[0030] Preferably, the overall structure of the filter is symmetrical about the middle metal layer 130, and the input and output ports can be used interchangeably.

[0031] The structural parameters of the filter are optimized by software simulation. In the embodiment of the present invention, the dielectric substrates of the upper and lower layers are both dielectric substrates TLY-5 with a thickness of 2.36 mm, the adhesive layer 140 is Rogers 4450B with a thickness of 0.1 mm, and the thickness of the metal layer is 0.035 mm. The overall resonant cavity size is 23.05 mm×20.67 mm×4.925 mm.

[0032] Figure 4 The S parameters of the millimeter wave folded SIW filter in one embodiment of the present invention are shown. In terms of the input and output excitation ports, a waveguide structure is used for feeding. Its passband insertion loss is less than 0.56dB, and the out-of-band suppression is greater than 25dB. The specific indicators are shown in Table 1, which shows the feasibility and feasibility of the present invention.

[0033] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A low-loss compact filter for broadband satellite communications, characterized in that: The invention comprises a top metal layer (110), an intermediate metal layer (130), a bottom metal layer (160), an upper dielectric substrate (120), a lower dielectric substrate (150), an adhesive layer (140), a metal short groove (170), and a metalized through-hole structure (180), wherein the upper dielectric substrate (120) and the lower dielectric substrate (150) are bonded to each other via the adhesive layer (140), the upper surface of the upper dielectric substrate (120) is provided with a top metal layer (110), and the upper dielectric substrate (150) is provided with a metal short groove (170). The lower surface of the dielectric substrate (120) is coated with an intermediate metal layer (130), the upper surface of the lower dielectric substrate (150) is coated with an adhesive layer (140), the lower surface of the lower dielectric substrate (150) is coated with a bottom metal layer (160), and the low-loss compact filter is formed by stacking a top metal layer (110), an upper dielectric substrate (120), an intermediate metal layer (130), an adhesive layer (140), a lower dielectric substrate (150) and a bottom metal layer (160).

2. A low-loss compact filter for broadband satellite communications according to claim 1, characterized in that: Eight hollow metal short slots (170) and a metallized through hole structure (180) are provided on the upper dielectric substrate (120), the adhesive layer (140) and the lower dielectric substrate (150). The metallized through hole structure (180) comprises a first metallized through hole (1801), a second metallized through hole (1802) and a third metallized through hole (1803).

3. A low-loss compact filter for broadband satellite communications according to claim 2, characterized in that: The hollow metal short groove (170) and the metallized through-hole structure (180) are both connected to the top metal layer (110), the upper dielectric substrate (120), the middle metal layer (130), the adhesive layer (140), the lower dielectric substrate (150) and the bottom metal layer (160).

4. A low-loss compact filter for broadband satellite communications according to claim 2, characterized in that: The eight hollow metal short slots (170) and four first metallized through holes (1801) located at opposite corners form a first resonant cavity, a second resonant cavity and a third resonant cavity. The first resonant cavity and the second resonant cavity, as well as the second resonant cavity and the third resonant cavity are connected via a common metallized through hole wall, and the common metallized through hole uses a discrete metal via second metallized through hole (1802) to form an inductor film hole (190) as a common metallized through hole wall.

5. A low-loss compact filter for broadband satellite communications according to claim 1, characterized in that: The top metal layer (110) is provided with a top rectangular groove (200), the middle metal layer (130) is provided with a middle rectangular groove (220), and the bottom metal layer (160) is provided with a bottom rectangular groove (210), the top rectangular groove (200) and the bottom rectangular groove (210) have the same relative position and size, the top rectangular groove (200) serves as an input port connected to a first resonant cavity, and the bottom rectangular groove (210) serves as an output port connected to a third resonant cavity, and is used to connect to waveguide feeding or to connect to external satellite communication equipment.

6. A low-loss compact filter for broadband satellite communications according to claim 3, characterized in that: The second resonant cavity is symmetrically distributed up and down about the middle metal layer (130).

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