CN110661067B

CN110661067B - Band-pass filter of dielectric integrated suspension line based on 5G double-frequency

Info

Publication number: CN110661067B
Application number: CN201910862414.8A
Authority: CN
Inventors: 马凯学; 张雯雯; 傅海鹏; 张皓
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2019-09-12
Filing date: 2019-09-12
Publication date: 2021-02-26
Anticipated expiration: 2039-09-12
Also published as: CN110661067A

Abstract

The invention discloses a 5G dual-frequency-based dielectric integrated suspended line band-pass filter, which comprises five dielectric plates, wherein the five dielectric plates are sequentially arranged from top to bottom, metal circuits are attached to the front and back surfaces of the five dielectric plates, and the middles of a second dielectric plate and a fourth dielectric plate from top to bottom are hollow structures to form two air cavities for metal shielding; the upper layer and the lower layer of the third dielectric plate are provided with filter circuits formed by transmission lines; the transmission lines include a G5 layer metal conductor transmission line, a pair of symmetrically arranged U-shaped resonators used as feed lines, and a G6 layer metal conductor transmission line, including two quarter-wave hairpin resonators for generating a first transmission band, two quarter-wave resonators, two symmetrically arranged capacitance loading stubs. The invention can generate extra zero point through electromagnetic coupling separation effect, and realize the circuit result with high isolation and high selectivity.

Description

Band-pass filter of dielectric integrated suspension line based on 5G double-frequency

Technical Field

The invention relates to the technical field of band-pass filters, in particular to a 5G dual-frequency-based band-pass filter of a dielectric integrated suspension line.

Background

A filter is a filter that screens out a specified frequency range of a signal or filters out a specified frequency range, leaving other frequencies behind. The radio frequency microwave filter is an integral part of systems such as satellite communication, wireless communication, modern microwave relay communication and the like. With the rapid development of wireless communication technology, frequency resources are increasingly in short supply, and the requirement of a communication system on large data volume without delay is higher and higher, at the moment, the requirement on dual-band filtering is also increasing. The dual-band filter can simultaneously screen out two frequency points, and the size and the complexity of equipment can be greatly reduced. The dual-band filter often comprises two single-band filters, the filter comprising the dual-band filter is complex in equipment, high in cost and large in size, the two filters are required to be adjusted, the complexity of the dual-band filter can be reduced, the high-suppression and high-selectivity dual-band filter can be realized, the integration level can be greatly improved, the resource saving and the cost reduction are greatly significant, and the development of emergency and science and technology is promoted. Therefore, the 5G-oriented dual-band filter has great market potential.

The prior dual-passband filter technology mainly comprises the following implementation methods: defected ground structures, stepped impedance resonators, multi-mode resonances, etc. The technology of dual-passband filters in the forms of SIW and waveguide has become more and more exquisite, but how to combine the advantages of microstrip lines and the advantages of waveguides and how to design structures with characteristics of smaller size, lower loss, higher isolation, higher Q value and the like is still a problem to be solved.

Disclosure of Invention

The invention aims to provide a low-loss, high-isolation and high-selectivity band-pass filter based on a 5G dual-frequency dielectric integrated suspension line, aiming at the problems of large size, no self-encapsulation, large insertion loss, low isolation and poor integration in the traditional filter.

The technical scheme adopted for realizing the purpose of the invention is as follows:

A5G dual-frequency-based dielectric integrated suspended line band-pass filter comprises five dielectric plates which are sequentially arranged from top to bottom, wherein metal circuits are attached to the five front and back surfaces of the five dielectric plates, and the middles of a second dielectric plate and a fourth dielectric plate from top to bottom are of hollow structures to form two air cavities for metal shielding; the upper layer and the lower layer of the third dielectric plate are provided with filter circuits formed by transmission lines; the periphery of the dielectric integrated suspension line is grounded through a copper column, and a self-packaging mode dielectric integrated suspension line is formed by pressing a dielectric plate and a metal plate through a rivet hole;

the transmission lines include a G5 layer metal conductor transmission line, a pair of symmetrically arranged U-shaped resonators used as feed lines, and a G6 layer metal conductor transmission line, including two symmetrical quarter-wave hairpin resonators for generating a first transmission band at 3.3-3.6GHz, two symmetrical quarter-wave resonators, two symmetrically arranged capacitive loading stubs.

Wherein the metal conductor transmission line of the G6 layer is folded to the G5 layer through a metal via.

Wherein, the part folded to the G5 layer is in an L-shaped structure and is symmetrically arranged.

Wherein, the third dielectric plate adopts Roger5880, the thickness of the plate is 0.254mm, and the dielectric constant is 2.2.

The invention adopts a transmission line structure, the G6 layer circuit generates two passbands, the G6 layer circuit part is folded to the G5 layer, the circuit size is further reduced, and an extra zero point can be generated through the electromagnetic coupling separation effect, thereby realizing the circuit result with high isolation and high selectivity.

Drawings

Fig. 1 is an exploded structural view of a 5G dual-band based dielectric integrated suspended line band pass filter of the present invention;

FIG. 2 is a combined cross-sectional structural view of a 5G dual band based dielectric integrated suspended line based band pass filter of the present invention;

FIG. 3 shows a circuit layout of layers G5, G6;

FIG. 4 is a schematic diagram of a U-shaped resonator with G5 layers;

FIG. 5 is a schematic diagram of a metal circuit of the G6 layer;

FIG. 6 is an isometric view of a metal circuit with a G6 layer;

FIG. 7 is a graph showing the results of the test experiment.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, the 5G dual-band dielectric integrated suspended line-based bandpass filter of the present invention includes a dielectric Substrate1, a dielectric Substrate2, a dielectric Substrate3, a dielectric Substrate4, and a dielectric Substrate5, which are sequentially arranged from top to bottom, wherein the dielectric Substrate2 and the dielectric Substrate4 are hollowed out and hollow out to form an air cavity for facilitating a metal shielding effect, the two cavities and the dielectric Substrate form an air cavity 3 therebetween, copper pillars are arranged around through the holes 1 for a grounding effect, the rest of the rivet holes press the dielectric and the metal plate to form a self-packaged dielectric integrated suspended line, and the upper and lower layers of the metal copper layers M5, M6 of the dielectric Substrate3 are used for arranging a filter circuit.

An air cavity is formed between the dielectric plate Substrate3 and the dielectric plate Substrate1, an air cavity is correspondingly formed between the dielectric plate Substrate3 and the dielectric plate Substrate5, and the metal layers G1-G4 and G7-G10, the two cavities and the G5 and G6 filter circuits form a complete filter together, so that not only can self-packaging be formed, the size is reduced, but also the complete electromagnetic shielding effect is achieved, and the in-band insertion loss can be reduced.

The G5 layer different-plane feeder line can enable the feed intensity and the excitation intensity to be larger than those of the traditional same-plane feeder line, the coupling from a source to a load is introduced, two extra zero points are generated, a better filtering effect is obtained, meanwhile, an electromagnetic separation structure is adopted, one more zero point can be generated again, and the selectivity and the out-of-band suppression effect are further improved.

The circuit of the G6 layer is folded and extends to the G5 layer through the metal through hole 2, so that the size of the filter can be further reduced, and the miniaturization and the integration are facilitated. The experimental results are shown in fig. 7, reaching the filter criteria.

In the invention, the filter is a double-pass band filter, and has low loss and small-sized transmission lines: the transmission line comprises a dielectric plate and metal conductor transmission lines designed on the front side and the back side of the dielectric plate, and the transmission lines are G5 layers and G6 layers respectively. The G5 layer metal conductor transmission line is a pair of symmetrically arranged "U" shaped resonators 4 used as a feed line, as shown in fig. 4-6. The metal conductor transmission line of the G6 layer circuit comprises a quarter-wave resonator 6, two symmetrically arranged capacitance loading branches 5, wherein the quarter-wave resonator 6 comprises two symmetrically arranged quarter-wave hairpin resonators 61 and two symmetrically arranged L-shaped quarter-wave resonators 62, as shown in fig. 4, wherein the two hairpin resonators of the G6 layer are used for generating a first transmission band at 3.3-3.6GHz, the upper arms are mainly used for electric coupling, and the coupling strength of the two resonators can be changed by changing the distance between the two arms and the area and length of the arms, so as to achieve matching from load, reduce insertion loss and improve isolation. Four quarter-wavelength resonators on the G6 layer are arranged at intervals in pairs, so that the area and the volume are saved, a new degree of freedom can be introduced into the capacitance loading branch, the capacitance adjustment is more convenient, and the change space of the coupling coefficient is larger.

In order to save space area, the circuit of the G6 layer is further folded to the G5 layer and connected through a metal via, as shown in fig. 6, the out-of-plane feeder of the G5 layer can increase the feed area, achieve more free excitation strength, have a larger coupling range between the source and the resonator, and further expand the range of the load quality factor.

Because the different-plane feeder line has the excitation intensity and the coupling intensity which are far greater than those of the same-plane feeder line, the space position of the feeder line is not limited by the shape and the area of a circuit any more, and the design mode is more flexible and wider. The non-coplanar feeder can simultaneously introduce the coupling from the source to the load, so that redundant zero points can be generated at high-frequency and low-frequency positions in the isolation band, the selectivity and the out-of-band rejection of the filter are improved, and clutter filtering is facilitated. More zeros can be introduced by electromagnetic coupling separation to further improve the band selectivity and the out-of-band rejection.

In order to better realize the filter with electromagnetic shielding and low insertion loss, the dual-band filter is integrated on a dielectric integrated suspension wire platform. The existing filter mostly adopts a microstrip line process, a special metal box needs to be customized for the existing filter to realize packaging, and the loss of the microstrip line and the loss caused by packaging can cause the filter to have larger insertion loss finally. Different microstrip circuit's encapsulation often corresponds different precision requirements to the assembly work that needs such as locating pin, locating hole, nut bolt all is extra work, all can improve the manufacturing cost of wave filter greatly.

In the invention, the dual-passband filter based on the dielectric integrated suspension line platform can realize self-packaging, an additional metal shielding box is not needed, the size of the filter can be greatly reduced, and the overall insertion loss of the filter can be reduced due to the excellent electromagnetic shielding effect. Auxiliary mechanical parts such as positioning pin positioning holes are not needed to assist in completing assembly, batch production is facilitated, and production cost is greatly reduced.

It should be noted that, in the present invention, the dielectric integrated suspension line platform is formed by laminating five dielectric plates, metal circuits are attached to the front and back surfaces of each dielectric plate, a hollow structure is formed between the second dielectric plate and the fourth dielectric plate, and the metal layers on the two surfaces of the third dielectric plate are used for designing a dual-passband filter structure for the design and implementation of circuits. Through the interaction of five plates, good electromagnetic shielding and self-packaging effects can be realized.

Preferably, the third dielectric plate will use Roger5880 as the dielectric material, the plate thickness is 0.254mm, the dielectric constant is about 2.2, and the plate surface can be plated with gold or other oxidation-resistant substances. The Roger5880 material is selected, the loss tangent is only 0.0009, and the dielectric loss of the circuit can be greatly reduced. The thickness of the plate is 0.254mm, so that the minimum plate thickness can be ensured under the condition that the strength of the substrate meets the standard, the dielectric loss of a circuit can be reduced, the electromagnetic fields in the upper air cavity and the lower air cavity can be distributed symmetrically and uniformly, the electromagnetic stability can be improved, and the anti-interference capability of the filter can be enhanced.

Compared with the prior art, the invention has the following advantages and beneficial results:

1. by employing a transmission line structure, the G6 layer circuit produces two passbands, and by folding the G6 layer circuit portion to the G5 layer, the circuit size is further reduced. Through the electromagnetic coupling separation effect, an additional zero point can be generated, and a circuit result with high isolation and high selectivity is realized.

The 2.5G dual-passband filter adopts a non-coplanar feed structure, overcomes the problems that the space size, the coupling strength and the excitation strength in the coplanar feeder are greatly limited by the circuit structure, can further introduce the coupling from a source to a load, introduces redundant zero points, realizes the steepness of upper and lower sidebands, and realizes the high isolation and the high selectivity of the filter.

Based on the scheme, the simulation effect of the invention meets the aim, the design of the 5G dual-band filter under the filter standard is met, the insertion loss is less than 1dB at 3.3-3.6GHz and 4.8-5GHz, the band isolation reaches-50 dB, the out-of-band rejection reaches-70 dB, the size of the traditional filter is reduced, and the transmission efficiency is improved.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A5G dual-frequency-based dielectric integrated suspended line band-pass filter is characterized by comprising five dielectric plates which are sequentially arranged from top to bottom, wherein metal circuits are attached to the five front and back surfaces of the five dielectric plates, and the middles of a second dielectric plate and a fourth dielectric plate from top to bottom are hollow structures to form two air cavities for metal shielding; the upper layer and the lower layer of the third dielectric plate are provided with filter circuits formed by transmission lines; the periphery of the dielectric integrated suspension line is grounded through a copper column, and a self-packaging mode dielectric integrated suspension line is formed by pressing a dielectric plate and a metal plate through a rivet hole;

the transmission lines comprise a G5 layer metal conductor transmission line, a pair of symmetrically arranged U-shaped resonators used as feeder lines, and a G6 layer metal conductor transmission line, comprising two symmetrical quarter-wave hairpin resonators for generating a first transmission band at 3.3-3.6GHz, two symmetrical quarter-wave L-shaped wavelength resonators, two symmetrically arranged capacitive loading stubs;

wherein the upper parts of the two hairpin resonators of the G6 layer are connected by an electric arm for electric coupling, and the coupling strengths of the two hairpin resonators are changed by changing the distance between the two electric arms and the areas and lengths of the electric arms; the four quarter-wave resonators on the G6 layer are arranged at intervals in pairs;

the metal conductor transmission line of the G6 layer is folded to the G5 layer through a metal via.

2. The 5G dual-band based dielectric integrated suspended line band-pass filter according to claim 1, wherein the third dielectric plate is Roger5880, the plate thickness is 0.254mm, and the dielectric constant is 2.2.