Resonator band-pass filter of meander line slow wave structure based on metal integrated suspended line structure

Abstract

The invention discloses a metal integrated suspended line structure-based resonator band-pass filter with a meander line slow-wave structure, which is formed by stacking and self-packaging a plurality of layers of metal plates from top to bottom to form a closed structure, and a filter circuit structure of the resonator band-pass filter with the meander line slow-wave structure is arranged on the metal plate in the middle. The middle parts of the metal plates on the upper layer and the lower layer of the filter circuit structure are hollowed to form cavities, so that the suspension of the filter circuit structure is realized. The filter disclosed by the invention has the characteristics of interference resistance, self-packaging, capability of flexibly regulating and controlling transmission zeros, relatively low loss, capability of realizing a slow wave effect and miniaturization, high processing precision, relatively simple and flexible manufacturing and assembling, capability of realizing N-1 transmission zeros in an N-order filter, and capability of realizing the transmission zeros in the N-order filter. By reasonably distributing transmission zero points in the upper stop band and the lower stop band of the pass band, high frequency selectivity and strong out-of-band rejection characteristics can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and in particular to a resonator bandpass filter with a slow-wave effect and a meander-line slow-wave structure based on a Metal Integrated Suspended Line (MISL) structure. Background Art

[0002] As an important circuit device in modern wireless communication systems, filters can allow specific frequency components in the input signal to pass smoothly in a low-loss manner, while filtering out other useless frequency components. The modern wireless communication technology industry is developing rapidly. Microwave filters, as important electronic components, are widely used in 5G communications, military radar, aerospace, remote sensing technology, radio broadcasting and other fields. The channels of modern wireless communications are becoming more and more crowded, which makes wireless spectrum resources more and more precious. At the same time, the performance of wireless communication systems is constantly improving, and the requirements for equipment miniaturization are getting higher and higher. Therefore, the study of high-frequency selectivity, low-loss, anti-interference, and miniaturized bandpass filters is of great significance for achieving excellent performance and miniaturization of wireless communication equipment, preventing signals from interfering with each other between different communication channels, and efficiently utilizing precious spectrum resources.

[0003] For microwave devices in today's wireless communication systems, the size of the components is comparable to the wavelength of the operating frequency, which means that even very small deviations in the manufacturing process of microwave devices will affect the performance of microwave devices. Therefore, in the design and manufacturing process of filters, there are problems such as large filter losses and susceptibility to external interference. There are also problems such as inflexible filter processing and packaging, large manufacturing errors, and large mass and volume. Summary of the invention

[0004] The object of the present invention is to overcome the deficiencies and defects of the prior art and to provide a meander line resonator bandpass filter based on a Metal Integrated Suspended Line (MISL) structure with a slow wave effect.

[0005] A resonator bandpass filter with a meander line slow-wave structure based on a metal integrated suspension line structure is formed by stacking multiple layers of metal plates from top to bottom and self-packaging to form a closed structure. A filter circuit structure of the resonator bandpass filter with a meander line slow-wave structure is arranged on a middle metal plate, and a cavity is hollowed out in the middle of the upper and lower metal plates of the filter circuit structure to realize the suspension of the filter circuit structure.

[0006] The filter circuit structure includes a plurality of cascaded resonators and an input and output feeder structure connected to ports; a single resonator is equivalent to a lumped capacitor connected to an inductor.

[0007] The metal plates on the upper and lower layers of the filter circuit structure are cut away at positions corresponding to the feeder structure to prevent the metal plates on the upper and lower layers from contacting the feeder and causing a short circuit.

[0008] The feeder lines of the input and output feeder line structures are directly connected to the two resonators on both sides.

[0009] Wherein, a plurality of the resonators are connected together in cascade to realize bandpass filter circuits of different orders.

[0010] Each of the resonators is composed of a meander line formed by bending a metal wire multiple times in a serpentine structure.

[0011] Each of the resonators is composed of a meander line formed by multiple vertical bends of a metal line in a serpentine structure.

[0012] Among them, the relative positions between the resonators, the density of the meander lines, the length of the short-circuit connecting lines and the relative positions of the input and output feeder lines are adjusted as needed to adjust the coupling strength and coupling relationship between the resonators, thereby realizing the regulation of the zero point position of the filter.

[0013] The multiple layers of metal plates are fixed together by fasteners through metallized through holes.

[0014] Wherein, the metal plate is a five-layer structure, and the thickness of the metal plate is 1 mm.

[0015] The filter of the present invention has the characteristics of anti-interference, self-packaging, flexible control of transmission zero points, low loss, ability to achieve slow wave effect and miniaturization, high processing accuracy, and relatively simple and flexible manufacturing and assembly. N-1 transmission zero points can be achieved in an N-order filter, and higher frequency selectivity and stronger out-of-band suppression characteristics can be achieved by reasonably distributing transmission zero points in the upper stopband and lower stopband of the passband.

[0016] The present invention is based on a metal integrated suspension wire platform and has the characteristic of flexible processing. The processing adopts computer numerical control (CNC) machine tool machining technology with high processing accuracy. The integration of multi-layer metal structures also makes processing and assembly more flexible.

[0017] The electromagnetic field of the filter structure of the present invention is mainly distributed in the cavity within the packaging structure, and has the characteristics of self-packaging and low loss. The all-metal structure avoids dielectric loss, and the overall closed structure prevents leakage of electromagnetic energy, thereby significantly reducing the loss of the structure and improving the filter quality factor and various performances.

[0018] The resonator of the filter of the present invention adopts a zigzag line structure with a slow wave effect, realizes the loading of capacitance and inductance, changes the equivalent dielectric constant of the structure, reduces the equivalent wave velocity of electromagnetic waves at the working frequency, and thus realizes the miniaturization of the circuit.

[0019] The filter of the present invention can achieve different center frequencies by changing the size and relative position of the resonators, adjust the strength of the electric coupling and magnetic coupling between the resonators, and realize flexible regulation of the position of the transmission zero point of the filter.

[0020] The filter of the present invention can realize a second-order, third-order or even higher-order bandpass filter by cascading multiple resonators, thereby generating transmission zeros on both sides of the passband, achieving a bandpass filter response with low in-band loss, high out-of-band suppression level and high frequency selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the expanded structure of the metal integrated suspended line structure filter.

[0022] Figure 2 This is an equivalent circuit diagram of the two resonators of the filter proposed in the present invention interacting with each other.

[0023] Figure 3 The third metal plate M of the filter proposed by the present invention 3 The structure and the schematic diagram of the filtering circuit therein.

[0024] Figure 4 This is a schematic diagram of S-parameter simulation of the filter proposed in the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] Metal Integrated Suspended Line (MISL) is a multi-layer metal structure. It has no substrate structure. It is based on the traditional suspension line and is constructed entirely of metal materials. The metal material structure makes it easy to process the actual device and has high processing accuracy. This closed structure has a good electromagnetic shielding effect, reduces external interference, reduces the dissipation of internal circuit energy, reduces the loss of the filter, and also has the characteristics of self-packaging.

[0027] The electromagnetic field of the filter with metal integrated suspension wire structure is mainly distributed in the air of its internal structure cavity, without dielectric loss, which further improves the performance of the filter. Each layer of the metal integrated suspension wire structure can be processed and manufactured separately, which greatly improves the flexibility of circuit and device design and manufacturing. At the same time, the multi-layer structure of metal integrated suspension wire is also conducive to solving the problem of large size of filters based on single plane design, and can overcome the shortcomings of traditional suspension wire circuits with complex assembly and large volume, which is conducive to improving the integration of circuit devices and achieving miniaturization.

[0028] Based on this, the present invention proposes a bandpass filter based on a metal integrated suspension line structure with a slow-wave effect. The filter is based on a metal integrated suspension line platform and adopts a metal meandering line structure with a slow-wave effect to realize the resonator, thereby realizing a bandpass filter design with self-packaging, miniaturization, flexible control of transmission zero point, low loss, and high frequency selectivity.

[0029] See also Figure 1 as well as Figure 3 As shown, a bandpass filter based on a metal integrated suspension line structure according to an embodiment of the present invention is composed of five layers of metal plates. After the five layers of metal are assembled, a closed self-encapsulated structure is formed. The first and fifth layers of metal are cover plates. The filter is synthesized using a metal integrated suspension line (MISL) structure and is composed of five layers of metal plates. The first layer of metal plate M 1 and the fifth metal plate M 5 The second metal plate M is a metal cover plate used to form a closed structure. 2 and the fourth metal plate M 4 The middle is hollowed out to form a cavity, and the third metal plate M 3 It carries the main filter circuit structure and realizes the suspension of the overall circuit of the third metal plate, including the three resonators of the filter and the input and output feeder structure, such as Figure 3 As shown, it shows the third metal plate M in the middle 3 structure.

[0030] Preferably, in the embodiment of the present application, Figure 1 The thickness of the five metal plates in the embodiment is 1 mm.

[0031] Among them, Figure 3 As shown, the feeder structure extending at the left and right ends of the third metal plate is used to connect to the port, and the corresponding positions of the second metal plate and the fourth metal plate at the third feeder are partially cut off to prevent the second metal plate and the fourth metal plate from contacting the feeder and causing a short circuit.

[0032] Specifically, Figure 3 As shown, in the embodiment of the present application, the length of the input and output feeder lines is 8 mm, the characteristic impedance of the input and output ports is 50 Ω, and they are directly connected to the two resonators on both sides, that is, the input and output feeder lines on both sides are respectively connected to the short-circuit ends of the nearest resonators.

[0033] In the present application, a single resonator can be regarded as a lumped capacitor connected to an inductor. By changing the relative position between the resonators, the density of the meander lines, the length of the short-circuit connecting line and the relative position of the input and output feed lines, the coupling strength and coupling relationship between the resonators can be adjusted, thereby achieving the regulation of the zero point position of the filter.

[0034] In the embodiment of the present application, the material of the metal plate can be aluminum, copper, stainless steel and the like, and is processed using CNC machine tool machining technology, and metallized through holes are punched at the edge of the structure and the multi-layer metal plates are fixed with screws. That is, during assembly, the five layers of metal plates can be fixed together using screws through the metallized through holes to achieve mechanical stability of the structure.

[0035] like Figure 3 As shown, in the embodiment of the present application, the three resonators are sequentially connected as follows Figure 3 The S parameters of this third-order filter example are shown in Figure 4 The center frequency of the bandpass filter is 0.7GHz, the fractional bandwidth of the passband response is 7.5%, and the insertion loss of the filter passband is 0.69dB. Three transmission poles are realized within the passband, and two transmission zeros are realized outside the passband. These zeros are distributed on both sides of the passband. This design enables the filter to have a low-loss and high-frequency-selective bandpass filter response, thereby showing excellent filtering performance.

[0036] In the above embodiments, the number of metal plate layers is not limited to five, but may be more, and the specific number is not limited. The filter may be composed of three zigzag resonators, or may be more, and the specific number is not limited. The drawings in the specification are only a preferred embodiment.

[0037] The design method of the bandpass filter based on the metal integrated suspension line structure according to the embodiment of the present invention is as follows:

[0038] After determining the required filter performance parameter indicators, the specific structure of the resonator is obtained, and according to the designed number and position of zero points and the required circuit level, the entire filter circuit is obtained by cascading the resonators. Among them, the equivalent circuit of the interaction between the two resonators is as follows Figure 2 shown.

[0039] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0040] Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is therefore intended that all changes falling within the meaning and range of equivalent elements of the claims are included in the present invention.

[0041] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A resonator bandpass filter based on a meander line slow wave structure with a metal integrated suspension line structure, characterized in that: A closed structure is formed by stacking multiple layers of metal plates from top to bottom and self-packaging. A filter circuit structure of a resonator bandpass filter with a zigzag slow-wave structure is arranged on the middle metal plate. A cavity is hollowed out in the middle of the upper and lower metal plates of the filter circuit structure to achieve suspension of the filter circuit structure.

2. According to claim 1, the resonator bandpass filter based on the meander line slow wave structure of the metal integrated suspension line structure is characterized in that: The filter circuit structure includes a plurality of cascaded resonators and an input and output feeder structure connected to ports; a single resonator is equivalent to a lumped capacitor connected to an inductor.

3. The resonator bandpass filter of the meander line slow wave structure based on the metal integrated suspension line structure according to claim 2 is characterized in that: The metal plates on the upper and lower layers of the filter circuit structure are cut away at positions corresponding to the feeder structure to prevent the metal plates on the upper and lower layers from contacting the feeder and causing a short circuit.

4. The resonator bandpass filter based on the meander line slow wave structure of the metal integrated suspension line structure according to claim 2 is characterized in that: The feed lines of the input and output feed line structure are directly connected to the two resonators on both sides.

5. The resonator bandpass filter based on the meander line slow wave structure of the metal integrated suspension line structure according to claim 2, characterized in that: A plurality of the resonators are connected in cascade to realize bandpass filter circuits of different orders.

6. The resonator bandpass filter based on the meander line slow wave structure of the metal integrated suspension line structure according to claim 2, characterized in that: Each of the resonators is composed of a meander line formed by bending a metal line multiple times in a serpentine structure.

7. The resonator bandpass filter based on the meander line slow wave structure of the metal integrated suspension line structure according to claim 6, characterized in that: Each of the resonators is composed of a meander line formed by multiple vertical bends of a metal line in a serpentine structure.

8. The resonator bandpass filter based on the meander line slow wave structure of the metal integrated suspension line structure according to claim 7, characterized in that: The relative positions of the resonators, the density of the meander lines, the length of the short-circuit connecting lines and the relative positions of the input and output feeder lines are adjusted as needed to adjust the coupling strength and coupling relationship between the resonators, thereby achieving regulation of the zero point position of the filter.

9. The resonator bandpass filter based on the meander line slow wave structure of the metal integrated suspension line structure according to claim 1, characterized in that: The multiple layers of the metal sheets are secured together using fasteners through metallized through holes.

10. The resonator bandpass filter based on the meander line slow wave structure of the metal integrated suspension line structure according to claim 1, characterized in that: The metal plate has a five-layer structure and a thickness of 1 mm.

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