Folded bandpass filter based on metal integrated suspended line structure

Abstract

The application discloses a folded band-pass filter based on a metal integrated suspended line structure, which is connected by a plurality of stacked multilayer circuit boards to form a self-enclosed structure; the multilayer circuit boards comprise a first layer of metal substrate, a second layer of metal substrate, a third layer of metal substrate, a fourth layer of metal substrate and a fifth layer of metal substrate arranged in sequence from top to bottom; the same size of the second layer of metal substrate and the fourth layer of metal substrate are hollowed out at the same position in the middle part to form an air-filled closed cavity; the circuit structure of the folded band-pass filter composed of a suspended line is located in the air cavity of the third layer of metal substrate, and coaxial feeding structures connected with the suspended transmission line are distributed in the two end cavities of the air cavity. The application has the self-enclosed characteristic, the multilayer metal plates are riveted and fixed, easy to assemble, the effective dielectric constant is small, the conductor loss is small, the dielectric loss is avoided, the folded band-pass filter is arranged in a folded type, the size of the filter is reduced, and the miniaturization requirement is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of band-pass filter, in particular to a folded band-pass filter based on metal integrated suspended line structure. BACKGROUND

[0002] Modern communication technology continues to progress, and the demand for band-pass filters with low loss and miniaturization is increasing. Such band-pass filters not only meet the requirements of electronic devices for compact size, but also improve energy efficiency, helping to improve the performance and expand the function of electronic systems.

[0003] However, the loss of existing band-pass filters still needs to be further reduced, and the overall performance has further room for improvement, and the processing is relatively complex and cannot be self-packaged. If the design process of the band-pass filter can further effectively reduce the loss while having the characteristics of self-packaging, further reducing the complexity of the filter processing and packaging, the overall performance of the filter can be greatly improved. SUMMARY

[0004] The purpose of the present application is to overcome the deficiencies and shortcomings of the prior art, and to provide a folded band-pass filter based on metal integrated suspended line structure with low loss, miniaturization and self-packaging.

[0005] A folded band-pass filter based on metal integrated suspended line structure is formed by stacking and connecting multiple layers of circuit boards to form a self-packaging structure. The multiple layers of circuit boards include first, second, third, fourth and fifth layers of metal substrates arranged from top to bottom. The second and fourth layers of metal substrates are hollowed out at the same size at the same position in the middle to form an air-filled closed cavity. The circuit structure of the folded band-pass filter composed of suspended lines is located in the air cavity of the third layer of metal substrate, and the coaxial feed structure connected to the suspended transmission line is distributed in the two end cavities of the air cavity.

[0006] Wherein, the material of each layer of metal substrate is aluminum.

[0007] Wherein, the thickness of each layer of metal substrate is the same.

[0008] Wherein, the thickness of each layer of metal substrate is 0.5mm.

[0009] Wherein, the cavity is a rectangular cavity, and has a matching cavity at both ends corresponding to the coaxial feed structure.

[0010] Wherein, each layer of metal substrate has a plurality of through holes, and the multiple layers of circuit boards are stacked together, the through holes penetrate all the metal substrates, and the multiple layers of circuit boards are connected by rivets inserted into the through holes to form a self-packaging structure.

[0011] The circuit structure of the folded band-pass filter is a vertical folded arrangement in a snake structure as a whole.

[0012] The folded band-pass filter comprises a three-order folded band-pass filter, three rectangular resonant cavities are connected in a vertical folded manner to form a complete filter circuit, and the filter circuit is a two-port network.

[0013] The first resonant cavity and the third resonant cavity are connected through the second resonant cavity, two ends of the filter circuit are connected with inner walls of the air cavity of the third layer metal substrate, and outer sides of connecting sections of the three resonant cavities are connected with the inner walls of the air cavity of the third layer metal substrate through a connecting part.

[0014] The folded band-pass filter based on the metal integrated suspended line structure has a self-encapsulation characteristic, multiple metal plates are stacked together, high-precision laser cutting is adopted, and rivets are used for fixation, so that the folded band-pass filter is easy to assemble; electromagnetic fields are mainly distributed in air, effective dielectric constant is small, conductor loss is small, and the folded band-pass filter is a full-metal structure, so that dielectric loss is avoided, and the folded band-pass filter has a low-loss characteristic; the resonant cavities are arranged in a folded manner, so that the size of the filter can be effectively reduced, and miniaturization requirements can be met. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic diagram of the folded band-pass filter based on the metal integrated suspended line structure.

[0016] Figure 2 is a schematic diagram of the three-order folded band-pass filter on the third layer metal substrate.

[0017] Figure 3 is an S parameter simulation diagram of the folded band-pass filter based on the metal integrated suspended line structure. DETAILED DESCRIPTION

[0018] The present application will be further described below in combination with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0019] Since the metal integrated suspended line technology integrates the multilayer circuit board to form a multilayer self-packaging structure, the circuit is designed in the suspended line layer, and the metal structure is used to realize the high-performance radio frequency, microwave and terahertz circuit with the characteristics of low loss and high Q value, therefore, based on the metal integrated suspended line technology, the application provides a folded bandpass filter based on a metal integrated suspended line structure, the folded bandpass filter based on the metal integrated suspended line, and the folded bandpass filter based on the metal integrated suspended line platform, and the filter designed by using the multilayer circuit structure has the characteristics of self-packaging, low loss and miniaturization.

[0020] The folded bandpass filter based on the metal integrated suspended line provided by the application has the structure as shown in Figure 1 After the multilayer circuit board is stacked, the first layer metal substrate 1, the second layer metal substrate 2, the third layer metal substrate 3, the fourth layer metal substrate 4 and the fifth layer metal substrate 5 are sequentially arranged from top to bottom.

[0021] The second layer metal substrate and the fourth layer metal substrate are hollowed out at the same position in the middle part to form an air-filled rectangular cavity with the same size, and the required folded bandpass filter circuit structure includes a suspended line, the air cavity is located on the third layer metal substrate, and the coaxial feed structure connected with the suspended transmission line is distributed at both ends of the air cavity.

[0022] In order to form a closed cavity structure, a plurality of through holes are punched on each layer of circuit board and penetrate all the metal substrates, and the multilayer circuit board is connected by penetrating the through holes through rivets to form a self-packaging structure.

[0023] In some embodiments, the thickness of each layer of metal substrate is the same, and is 0.5 mm.

[0024] In some embodiments, the materials of the five layers of metal substrates from top to bottom are all aluminum materials, and of course can be other metal materials, such as copper or composite metal materials.

[0025] When the circuit is specifically designed, according to the actual demand, the required working frequency band and the circuit order are determined, and after filter synthesis, three rectangular resonant cavities are designed in a folded type to form a complete filter circuit.

[0026] Figure 2 As shown in the figure, it is an embodiment of a three-order folded bandpass filter, and the main circuit structure of the three-order folded bandpass filter is a two-port network. Figure 2 As shown in the figure, the circuit structure of the folded bandpass filter is vertically folded in a snake-shaped structure.

[0027] Specifically, the third-order folded band-pass filter adopts three rectangular resonant cavities connected in a vertical folded mode to form a complete filter circuit, which is a two-port network, the input port is connected to the left end of the first resonant cavity, and the output port is connected to the right end of the third resonant cavity, and the three resonant cavities are arranged in a folded structure.

[0028] The first resonant cavity and the third resonant cavity are connected through the second resonant cavity, two ends of the filter circuit are connected to the inner wall of the air cavity of the third layer of metal substrate, and the outer side of the connecting section of the three resonant cavities is connected to the inner wall of the air cavity of the third layer of metal substrate through a connecting part.

[0029] The S parameter simulation diagram realized by the embodiment is shown in Figure 3 The horizontal axis is frequency, unit: GHz, and the vertical axis is S parameter, unit: dB. The center frequency of the embodiment is 8.13 GHz, there are three transmission poles in the passband, the return loss is lower than -20 dB, and good filter performance is realized.

[0030] The above shows and describes the basic principles and main features of the present application and the advantages of the present application, and it is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or essential characteristics of the present application.

[0031] Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

[0032] In addition, it should be understood that although the present application is described in the specification in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be properly combined to form other embodiments which can be understood by those skilled in the art.

Claims

1. A folded bandpass filter based on a metal integrated suspended line structure, characterized in that, The multiple-layer circuit board is connected by stacking and forms a self-encapsulation structure; the multiple-layer circuit board comprises a first layer of metal substrate, a second layer of metal substrate, a third layer of metal substrate, a fourth layer of metal substrate and a fifth layer of metal substrate arranged in sequence from top to bottom; the second layer of metal substrate and the fourth layer of metal substrate are hollowed out in the same size at the same position in the middle part to form an air-filled closed cavity, and the circuit structure of the folded band-pass filter composed of suspended lines is located in the air cavity of the third layer of metal substrate, and the coaxial feeding structure connected with the suspended lines is distributed in the two end cavities of the air cavity; the circuit structure of the folded band-pass filter is vertically folded in a snake-shaped structure as a whole; the folded band-pass filter comprises a three-order folded band-pass filter, three rectangular resonant cavities are used to form a complete filter circuit by vertical folding connection, and the filter circuit is a two-port network, the input port is connected with the left end of the first resonant cavity, and the output port is connected with the right end of the third resonant cavity; the first resonant cavity and the third resonant cavity are connected through the second resonant cavity, the two ends of the filter circuit are connected with the inner wall of the air cavity of the third layer of metal substrate, and the outer side of the connecting section of the three resonant cavities is connected with the inner wall of the air cavity of the third layer of metal substrate through a connecting part.

2. The folded bandpass filter based on a metal integrated suspended line structure according to claim 1, characterized in that, The material of each layer of metal substrate is aluminum.

3. The folded bandpass filter based on metal integrated suspended line structure according to claim 1, wherein, The thickness of each layer of metal substrate is the same.

4. The folded bandpass filter based on metal integrated suspended line structure according to claim 1, wherein, The thickness of each layer of metal substrate is 0.5 mm.

5. The folded bandpass filter based on metal integrated suspended line structure according to claim 1, wherein, The cavity is a rectangular cavity, and has a matching cavity at the two ends corresponding to the coaxial feeding structure.

6. The folded bandpass filter based on metal integrated suspended line structure according to claim 1, wherein, Each layer of metal substrate has a plurality of through holes, the multiple-layer circuit board is stacked together, the through holes penetrate all the metal substrates, the multiple-layer circuit board is connected by rivets installed in the through holes, and a self-encapsulation structure is formed.

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