CN202121040U - High defect coplanar waveguide double-frequency filter - Google Patents

Abstract

The utility model relates to a high defect coplanar waveguide double-frequency filter which is composed of a front side metallic signal layer, a middle layer, and a bottom layer, and is characterized in that the front side metallic signal layer has a section of central conduction band, the two sides of the central conduction band are grounding metal conductive planes, and the grounding conductive plane is provided with a spurline type defected ground structure and a short-circuited stub with the inductance coupling characteristic. The middle layer is a medium plate, the bottom of the medium plate is not provided with a metal coating. Compared with a conventional coplanar waveguide filter, the S11 in a pass band of the novel double-frequency filter is smaller, the in-band insertion loss is small, so the high defect coplanar waveguide double-frequency filter has an ultra wide stop band characteristic, and restrains the first, the second, and the higher harmonic. The high defect coplanar waveguide double-frequency filter is simple in structure, high in processing precision, and is easy to operate and process. In addition, the filter only has one side, so the filter can be applied to the development of a multilayer board to realize the miniaturization.

Description

High defect coplanar waveguide dual frequency filter

technical field

The utility model relates to a high-defect coplanar waveguide dual-frequency filter, which belongs to the category of dual-frequency bandpass filters in the technical field of wireless communication.

Background technique

The ever-expanding huge amount of information in the modern information society requires communication technology to develop towards high speed, broadband, and large capacity, which means that the frequency of use of electromagnetic waves, the information dissemination medium, continues to expand to higher frequency bands. At the same time, the single-band communication system has become obsolete and cannot meet the needs of wireless communication well. With the rapid development of wireless communication, the single-band communication system shows its limitations more and more.

In order to make full use of the existing spectrum and basic equipment resources, one of the effective ways to set up multiple communication frequency bands that can work simultaneously in the communication system is to research and develop high-performance dual-band microwave filters, and use one device to realize two devices. The work can not only save resources but also reduce expenses. The rapid development of modern communication requires the effective use of more and more frequency channels. In order to reduce the volume and weight of communication circuit equipment, the research of dual-band devices has attracted more and more attention. Therefore, the research on dual-band filters has important significance and practical value.

Traditional filter design is based on microstrip transmission lines, which is not conducive to engineering integration and has a large area, which is a major problem in the design of microwave and millimeter wave integrated circuits. The coplanar waveguide is an important microwave planar transmission line developed from the microstrip transmission line. Compared with conventional microstrip transmission lines, coplanar waveguides are easy to manufacture, easy to realize the series and parallel connection of passive and active devices in microwave circuits, small parasitic parameters, good dispersion characteristics, and easy to increase circuit density. Therefore, Coplanar waveguides are widely used in integrated circuits such as microwaves, millimeter waves, optics, and high-temperature superconductors. Therefore, it is of great significance to explore the use of coplanar waveguides as the basis of transmission lines and to manufacture dual-band filters with excellent performance.

Utility model content

The purpose of the utility model is to provide a high-defect coplanar waveguide dual-frequency filter aiming at the defects existing in the prior art. This kind of filter is simple in design, small in size, easy to process, low in-band loss, and has good harmonic suppression characteristics, and realizes the miniaturization of the filter.

For achieving the above object, design of the present utility model is:

(1) On the basis of the traditional DGS, a new DGS structure is proposed, which has deeper stop-band suppression and better slow-wave characteristics, and improves the stop-band suppression characteristics of the filter.

(2) On the basis of the traditional coplanar waveguide filter, a new DGS structure and an open circuit branch are added to realize a new coupling, and the position of the center frequency point can be changed by changing the coupling spacing.

=10.2，厚度h=0.635mm。 (3) The utility model adopts the following dielectric plate materials: the dielectric constant of the dielectric substrate is

=10.2, thickness h =0.635mm.

(4) The processed circuit board is one layer, the reverse side has no metal coating, and the front side includes a metal coating etched coplanar waveguide structure and a new defect ground structure, in which two SMA connectors are welded at both ends of the microstrip for actual measurement .

According to above-mentioned utility model design, the utility model adopts following technical scheme:

A high-defect coplanar waveguide dual-frequency filter, consisting of a front metal signal layer, an intermediate layer and a bottom layer, is characterized in that the front metal signal layer has a central conduction band, and the two sides of the central conduction band are grounded metal conductive The ground plane on both sides has a fork-type defect structure and a short-circuit stub with inductive coupling characteristics. The middle layer is a dielectric board, and the bottom surface of the dielectric board has no metal plating.

The structure of the bifurcated line defect is as follows: two side-by-side squares are etched on the metal conductive plane. There is an etching groove on the left and right sides of the two squares, and the outer end of the etching groove is connected to the square. And the inner end is connected to a horizontal etching groove located inside the square, one end of the lateral etching groove is connected to the short-circuit branch, and the other end is vertically bent for a small section around the square; the short-circuit branch is: between the two squares Two vertical parallel slots are respectively etched on the left side and the right side, the outer ends of the two slots are slightly higher than the square, and the inner ends are slightly higher than the horizontal etching groove.

=10.2的介质板，该介质板厚度h =0.635mm±0.05mm。   The dielectric plate layer is a dielectric constant

=10.2 medium plate, the thickness of the medium plate h =0.635mm±0.05mm.

The metal microstrip line may be a metal material with good electrical conductivity, such as gold, silver, or copper.

Compared with the prior art, the utility model has the following obvious substantive features and advantages:

(1) The utility model has a simple structure and is easy to process. Since this structure is to directly etch the DGS structure and the open branch to form a filter on the surface of the coplanar waveguide, the processing precision is high, simple and easy, and is beneficial to integration.

(2) Compared with the traditional planar structure, the radiation loss is smaller, which is conducive to the application in the microwave band. Compared with the traditional waveguide structure, it is small in size, high in integration, low in price, and easy to process, and can be realized by PCB or LTCC technology.

(3) A new DGS structure is added to the structure of the traditional coplanar waveguide filter, which has better harmonic suppression characteristics and low in-band loss. At the same time, changing the area of the DGS structure can also adjust the center frequency of the two passbands Location.

Description of drawings

Figure 1 Schematic diagram of the traditional dumbbell-shaped DGS unit structure.

Fig. 2 Schematic diagram of the new fork-line DGS unit structure.

Figure 3 Schematic diagram of the structure of a traditional coplanar waveguide filter.

Fig. 4 Schematic diagram of the structure of the high-defect coplanar waveguide filter.

Figure 5 Frequency response plot of a conventional coplanar waveguide filter.

Figure 6. Frequency response plot of a high-defect coplanar waveguide filter.

Detailed ways

Below in conjunction with accompanying drawing, preferred embodiment of the present utility model is described in detail:

The schematic diagram of the new branch line type DGS unit structure proposed by the utility model is shown in Fig. 2 . It moves the traditional dumbbell-shaped DGS unit structure, as shown in Figure 1, the middle rectangular connecting part is moved to one side, and a metal stub is added to the two rectangular etching parts, thereby affecting the propagation of the TE ₁₀ mode. In the picture, the gray areas are metallized, and the white areas do not have any metal coating. The position of passband and transmission zero can be adjusted by changing the size of the resonator, and the coupling between the two resonators can be changed by changing the width of the metal conduction band part directly between the two resonators, so that the frequency response of the filter can be adjusted.

Figure 3 is a schematic structural diagram of a traditional coplanar waveguide filter. Fig. 4 is a schematic structural diagram of a high-defect coplanar waveguide filter.

Embodiment one:

Referring to Figure 4, this high-defect coplanar waveguide filter is composed of a front metal signal layer, an intermediate layer and a bottom layer, and is characterized in that the front metal signal layer has a central conduction band, and the two sides of the center conduction band are grounded metal conductive The ground plane on both sides has a fork-type defect structure and a short-circuit stub with inductive coupling characteristics. The middle layer is a dielectric board, and the bottom surface of the dielectric board has no metal plating. Among them, the dielectric constant of the PCB board is 10.2, and the thickness of the board is 0.635mm.

Embodiment two:

This embodiment is basically the same as Embodiment 1, and the special feature is that the structure of the branch line defect is: two side-by-side squares are etched on the metal conductive plane, and the left and right sides of the two squares are respectively There is an etching groove, the outer end of which is connected to the square, and the inner end is connected to a horizontal etching groove located inside the square. square; the short-circuit branch is: two vertical and parallel slots are respectively etched on the left and right sides of the two squares, the outer ends of the two slots are slightly higher than the square, and the inner ends are slightly higher than the horizontal etching groove.

Embodiment three:

This embodiment is basically the same as embodiment two, and the special features are:

Figure 4 is a schematic structural diagram of this embodiment. After design, simulation and optimization, the specific dimensions of the high-defect coplanar waveguide dual-frequency filter are finally determined as follows:

S=0.4mm, W=1.4mm, g=0.25mm, g1=0.2mm, d1=1.5mm, d2=2.7mm,

L1=5mm, L2=4.6mm, L3=5.8mm, L4=1.5mm,

W1=0.3mm, W2=0.3mm, W3=0.7mm, W4=0.3mm, W5=0.4mm.

Based on the above method, a microwave filter with a center frequency of 2.65GHz/4.46GHzz and a relative bandwidth of about 2%/6.7% was designed, which was simulated and debugged by the electromagnetic simulation software HFSS.

Figure 5 shows the frequency response of a conventional coplanar waveguide filter.

Fig. 6 shows the frequency response of the high-defect coplanar waveguide filter, and the simulation results show that the present invention has good advantages in both in-band characteristics and out-of-band suppression, and the in-band insertion loss is small. Moreover, the structure of the filter is simple, the size is small, and miniaturization is realized.

The above simulation results show that:

(1) The passband bandwidth is about 30MHz/600MHz, and the in-band insertion loss is less than 2dB.

(2) It has a wide stop-band suppression characteristic, and the out-of-band is below -20dB from 4.98GHz to 12.5GHz.

(3) After achieving good in-band and out-of-band performance, the structure of the microstrip is simple, the size is also miniaturized, the printing is simple, and the material loss is relatively small.

Claims (3)

1. A high-defect coplanar waveguide dual-frequency filter is composed of a front metal signal layer, an intermediate layer and a bottom surface layer, and is characterized in that the front metal signal layer has a section of central conduction band (1), a central conduction band (1 ) on both sides are grounded metal conductive planes (2), and on both sides of the grounded planes (2) there are bifurcated line-type defect ground structures (3) and short-circuit stubs (4) with inductive coupling characteristics, and the middle layer is a dielectric board (6), there is no metal coating (7) on the bottom surface of the dielectric plate (6). 2. The high-defect coplanar waveguide dual-band filter according to claim 1, characterized in that the structure (3) of the bifurcated line defect is: two side by side are etched on the metal conductive plane (2) square (10), the two squares (10) have an etching groove (8) on the left and right sides respectively, the outer end of the etching groove (8) is connected with the square (10), and the inner end is connected with a A horizontal etching groove (9) inside the square, one end of the horizontal etching groove (9) is connected to the short-circuit branch (4), and the other end is vertically bent for a small section (11) to surround the square (10); the short-circuit branch ( 4) is: two vertical and parallel slots (5) are respectively etched on the left and right sides of the two squares (10), the outer ends of the two slots (5) are slightly higher than the squares (10), and The inner end slightly exceeds the lateral etching groove (9). 3. The high-defect coplanar waveguide dual-frequency filter according to claim 1, characterized in that the dielectric plate (6) has a dielectric constant =10.2 medium plate, the thickness of the medium plate h =0.635mm±0.05mm.

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