A broadband dielectric filter

Abstract

A broadband dielectric filter, belonging to the field of electronic component technology, includes a substrate, through-holes, resonant circuit patterns, electrodes, a signal input port, and a signal output port. The substrate has three or more through-holes penetrating both the front and back surfaces, with the inner walls of the through-holes silvered. Resonant circuit patterns are formed on both the front and back surfaces of the substrate, with the through-holes and their connected resonant circuit patterns collectively constituting a resonator. Surface electrodes are printed on the bottom surface of the substrate. The resonant circuit patterns of the resonators are sequentially distributed on the front and back surfaces of the substrate, forming an interdigitated structure. The signal input port is connected to a first resonator and its electrodes, and the signal output port is connected to a final resonator and its electrodes. This invention solves the problem in existing technologies where increasingly smaller spacing of the resonant circuit patterns limits the bandwidth of the dielectric filter due to manufacturing difficulties and precision constraints. It has broad application prospects in miniaturization and high bandwidth applications in various communication systems.

Description

Technical Field

[0001] This utility model belongs to the field of electronic components technology, and more specifically to the field of filter technology, and more specifically to a broadband dielectric filter. Background Technology

[0002] In wireless communication technology, dielectric filters are widely used in various mobile communication systems, satellite communication systems, aerospace and other communication engineering projects due to their small size, low loss, high power tolerance and easy installation.

[0003] Current communication and radar products are trending towards broadband and ultra-wideband, making traditional dielectric filter structures increasingly inadequate for bandwidth requirements. Conventional dielectric filters achieve strong coupling bandwidth through electrical coupling between resonant circuit patterns. Therefore, current technologies typically increase coupling bandwidth by reducing the spacing between adjacent resonant circuit patterns; this method usually achieves design requirements with a relative bandwidth below 20%. However, when the relative bandwidth requirement exceeds 20%, the spacing between resonant circuit patterns needs to be increasingly smaller, which becomes unacceptable due to limitations in manufacturing difficulty and precision.

[0004] like Figure 1 , Figure 2 , Figure 3 As shown, based on the principle of filters, Figure 1 The equivalent circuit diagram of a traditional dielectric filter is shown below. Figure 3 As shown, the through-hole 2 coated with a silver layer on the inner wall and the silver layer resonant pattern 3 connected to it together form a resonator. The equivalent inductance and capacitance based on the dimensions of the through-hole 2 and the resonant pattern 3 form an LC oscillator. In traditional dielectric filter design, all resonant patterns are fabricated on the front side of the ceramic body 1, and all the formed resonators are oriented in the same direction, arranged in a straight line; this structure is called a comb structure. Each pair of adjacent resonators will generate electromagnetic coupling according to the designed structure, and the coupling amount is equivalent to that of a coupler in a circuit. In the coupling structure of the comb resonator, if a coupling amount with a relative bandwidth of more than 20% is required, the spacing between adjacent resonant patterns needs to be less than 0.05 mm. This spacing exceeds the accuracy range that current manufacturing processes can meet.

[0005] The Chinese patent database contains the following patents related to broadband dielectric filters: "A Broadband Filter with Improved Out-of-Band Rejection" (publication number CN201520515844.X), "A Broadband Filter Structure" (publication number CN202411438012.2), "A High-Suppression Broadband Dielectric Filter" (publication number CN202110679488.5), "A Dielectric Filter that Improves In-Band Echo of a Broadband Dielectric Filter" (publication number CN202311399431.5), and "A High-Bandwidth Dielectric Filter" (publication number CN202310167542.7). However, to date, no application has been submitted that utilizes the technical solution described in this utility model to achieve the high bandwidth requirements of a dielectric filter.

[0006] In view of the above, this utility model is hereby proposed. Summary of the Invention

[0007] The technical problem to be solved by this utility model is that as the spacing of resonant circuit patterns becomes smaller, it becomes difficult to improve the bandwidth of dielectric filters due to limitations in processing difficulty and precision.

[0008] The inventive concept of this utility model is to avoid the traditional electrical or magnetic coupling of comb resonators and adopt an interdigital coupling structure to achieve high coupling bandwidth.

[0009] Therefore, this utility model provides a broadband dielectric filter, such as... Figure 4-8 As shown. Includes: 1. Substrate; 2. Through hole; 3. Resonant circuit pattern; 4. Electrode; 5. Signal input port; 6. Signal output port.

[0010] The substrate is a ceramic substrate. The substrate has three or more through holes penetrating both the front and back sides, with the inner walls of the through holes being silver-plated. Resonant circuit patterns are provided on both the front and back sides of the substrate, and the through holes and the resonant circuit patterns connected to them together form a resonator.

[0011] The resonant circuit pattern of the resonator has odd-numbered resonant patterns on the front and even-numbered resonant patterns on the back. Adjacent resonators are in opposite directions, forming an interdigital structure.

[0012] The electrodes are fabricated on the bottom surface of the filter substrate. The input electrode and the output electrode are directly connected to the input port circuit layer pattern and the output port circuit layer pattern, respectively, to form the signal input structure and the signal output structure.

[0013] The signal input port is connected to the first resonator, and the signal output port is connected to the last resonator. The corresponding port circuit layer patterns and resonant patterns transmit signals through electromagnetic coupling or direct feeding.

[0014] The signal input port, the first resonator, the intermediate resonator, the last resonator, and the signal output port are sequentially coupled together.

[0015] The surfaces of the electrodes, resonator, signal input port, and signal output port are silver-plated.

[0016] This invention avoids the predicament of increasingly smaller capacitive coupling spacing in the high-bandwidth design of traditional dielectric filters. By adopting an interdigital coupling design, it easily achieves high bandwidth and has broad application prospects in miniaturization and high bandwidth fields of various communication systems. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of a traditional fifth-order dielectric filter.

[0018] Figure 2 This is a schematic diagram of the coupling structure of a traditional fifth-order dielectric filter.

[0019] Figure 3 This is a schematic diagram of the equivalent circuit principle of a traditional fifth-order dielectric filter.

[0020] Figure 4 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention.

[0021] Figure 5 This is a front structural diagram of Embodiment 1 of the present invention.

[0022] Figure 6 This is a schematic diagram of the reverse side structure of Embodiment 1 of the present invention.

[0023] Figure 7 This is a front view of the structure of Embodiment 2 of the present invention.

[0024] Figure 8 This is a schematic diagram of the bottom structure of Embodiment 3 of the present invention.

[0025] In the diagram: 1 is the substrate, 2 is the through hole, 3 is the resonant circuit pattern, 4 is the electrode, 5 is the signal input port, 6 is the signal output port, and 7 is the capacitive coupling line. Detailed Implementation

[0026] like Figure 4-8 As shown, the broadband dielectric filter is specifically implemented as follows: The through hole is a circular through hole.

[0027] The number of passes is 5.

[0028] The substrate is a square ceramic planar substrate.

[0029] Implementation Case 1: Capacitive coupling is used for the coupling between the signal terminal and the resonator port. like Figure 4 As shown, the substrate 1 is a cube made of sintered ceramic material, with five through holes 2 inside. The resonant pattern 3 is arranged sequentially on the front and back of the substrate, and the surface electrode 4 is printed on the bottom surface.

[0030] like Figure 5-6 As shown, resonant circuit patterns 3 are printed on the front and back sides of the substrate 1, respectively. Each via and the resonant circuit pattern connected to it constitute a resonator. Each electrode and the port circuit layer pattern connected to it constitute a signal input port 5 and a signal output port 6. The signal input port is capacitively coupled to the first resonator, and the signal output port is capacitively coupled to the fifth resonator. Adjacent resonators achieve high-bandwidth coupling through interdigital coupling.

[0031] Implementation Case 2: Direct feed coupling is used for the coupling between the signal terminal and the resonator port. like Figure 7 As shown, based on Implementation Case 1, signal input port 5 is directly connected to the first resonator, and signal output port 6 is directly connected to the fifth resonator. The port coupling method is changed to direct power-feed coupling. As bandwidth requirements increase, the capacitive coupling in Case 1 requires increasingly smaller spacing between the port circuit layer patterns, leading to increased processing difficulty and precision. Direct power-feed coupling can achieve strong port coupling, avoiding the problems caused by strong capacitive coupling.

[0032] Implementation Case 3: Adding capacitive coupling lines between non-adjacent resonators like Figure 8 As shown, based on Implementation Case 1, a capacitive coupling line 7 is provided on the bottom surface of the substrate 1 between the second and fourth resonators. Through the capacitive coupling line, the second and fourth resonators will generate an electrical coupling, forming a design structure with a transmission zero, which enhances stopband suppression.

[0033] In summary, this invention provides a broadband dielectric filter that achieves strong coupling bandwidth through interdigital coupling, while also using feed coupling to enhance port coupling. Furthermore, it allows for flexible design of transmission zero-point enhancement and stopband suppression through the design of capacitive coupling lines. This solves the problem that traditional dielectric filters cannot achieve high bandwidth, enabling applications in miniaturization and high bandwidth fields in various communication systems.

[0034] Finally, it should be noted that the above embodiments are merely examples for clear illustration. This utility model includes, but is not limited to, the above embodiments, and it is neither necessary nor possible to exhaustively describe all implementation methods. Those skilled in the art can make other variations or modifications based on the above description. All implementation schemes that meet the requirements of this utility model are within the protection scope of this utility model.

Claims

1. A broadband dielectric filter, characterized in that: This includes the substrate, vias, resonant circuit patterns, electrodes, signal input ports, and signal output ports. The substrate is a ceramic substrate; The substrate has three or more through holes penetrating the front and back sides of the substrate, with the inner walls of the through holes being silvered; the front and back sides of the substrate have resonant circuit patterns, and the through holes and the resonant circuit patterns connected to them together form a resonator. Print surface electrodes on the bottom surface of the substrate; The resonant circuit pattern of the resonator is sequentially distributed on the front and back of the substrate, forming an interdigitated structure; The signal input port is connected to the first resonator and the first resonator electrode, and the signal output port is connected to the last resonator and the last resonator electrode. The signal input port, the first resonator, the intermediate resonator, the last resonator, and the signal output port are sequentially coupled together. The surfaces of the resonator, signal input port, and signal output port are silver-plated.

2. A broadband dielectric filter as described in claim 1, characterized in that: The through hole is a circular through hole.

3. A broadband dielectric filter as described in claim 1, characterized in that: The number of through holes is 5.

4. A broadband dielectric filter as described in claim 1, characterized in that: The substrate is a square ceramic planar substrate.

5. A broadband dielectric filter as described in claim 1, characterized in that: The first resonator electrode and its connected port circuit layer pattern form a signal input port, and the last resonator electrode and its connected port circuit layer pattern form a signal output port. The signal input port is capacitively coupled to the first resonator, and the signal output port is capacitively coupled to the fifth resonator. Adjacent resonators are high-bandwidth coupled through interdigital coupling.

6. A broadband dielectric filter as described in claim 1, characterized in that: The signal input port is directly connected to the first resonator, and the signal output port is directly connected to the fifth resonator. The port coupling method is direct power-feed coupling connection.

7. A broadband dielectric filter as described in claim 1, characterized in that: A capacitive coupling line is provided between the second and fourth resonators to increase the coupling connection channel of the capacitive coupling line.

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