CN209747694U

CN209747694U - Low-pass filter with complementary split resonant ring and U-shaped groove defected ground

Info

Publication number: CN209747694U
Application number: CN201920391329.3U
Authority: CN
Inventors: 张中华; 夏铭; 熊荆; 毛小平
Original assignee: CHONGQING VOCATIONAL INSTITUTE OF SAFETY & TECHNOLOGY
Current assignee: CHONGQING VOCATIONAL INSTITUTE OF SAFETY & TECHNOLOGY
Priority date: 2019-03-26
Filing date: 2019-03-26
Publication date: 2019-12-06
Anticipated expiration: 2029-03-26

Abstract

the utility model discloses a low pass filter of complementary opening resonant ring and U groove defect ground. The key points are as follows: the low-pass filter comprises a dielectric substrate, an opening resonant ring and two U-shaped groove structures are etched and compensated on the bottom layer of the dielectric substrate in a metal mode, the top layer of the dielectric substrate is composed of an I-shaped microstrip line, a transmission microstrip line and two open-circuit branch lines, and microstrip feeder lines are arranged at two ends of the top layer. The novel transmission characteristic and the coupling of utilizing "I" type microstrip line and complementary opening resonant ring form the passband, adopt the coupling of the branch line of opening a way to produce transmission zero, strengthen the outband rejection characteristic, improve the selectivity of wave filter.

Description

Low-pass filter with complementary split resonant ring and U-shaped groove defected ground

Technical Field

the utility model relates to an use the filtering at wireless communication system, especially relate to a low pass filter of complementary opening resonant ring and U groove defect ground.

background

With the rapid development of wireless communication technology, devices are continuously climbing, signal frequency domains are crowded, and communication systems of various frequency bands are in succession. In order to avoid mutual interference between frequency bands, a high-quality filter is an indispensable component in a communication system.

The planar microstrip structure has the advantages of small volume, easy integration, simple processing and the like; the defect ground structure changes the distributed inductance and the distributed capacitance of the transmission line, and obtains the band stop characteristic, the slow wave characteristic and the like, the slow wave characteristic can be used for realizing the miniaturization design of the filter, and the band stop characteristic can be used for realizing the design of the stop band filter. Therefore, the low-pass filter is designed by utilizing the planar microstrip and defected ground technology, and the advantages of small size, high performance, easy integration and the like of the filter are realized.

SUMMERY OF THE UTILITY MODEL

The utility model discloses a main objective adopts microwave integrated circuit's plane transmission line and defect ground technique, combines complementary opening resonance ring, U groove defect ground structure and plane microstrip structure's transmission characteristic, provides a high selectivity, low-loss low pass filter.

The purpose of the utility model is realized through the following technical scheme:

A complementary split ring resonator and U-slot defected ground low pass filter comprising: a top layer, a dielectric substrate layer and a bottom layer of a metal.

The top layer is provided with an I-shaped microstrip line (2), a left transmission microstrip line (5), a right transmission microstrip line (6), a left open-circuit branch line (7) and a right open-circuit branch line (8), and the microstrip feeder is positioned at two ends of the structure.

The bottom layer is etched with the complementary opening resonance ring (1), the U groove (3) and the inverted U groove (4) in a metal mode. The U groove (3) and the inverted U groove (4) are in an axisymmetric structure, and the complementary split resonant ring (1) is positioned in the structure formed by the U groove (3) and the inverted U groove (4). The I-shaped microstrip line (2) and the complementary open-ended resonant ring (1) are coupled to form a pass band, and an open-loop branch line coupling is adopted to generate a transmission zero point, so that the out-of-band rejection characteristic is enhanced, and the selectivity of the filter is improved.

The bottom layer metal ground etching complementary opening resonance ring (1) comprises a gap (1-1) and a gap (1-2), and the opening directions of the gaps are opposite; the bottom layer is etched with metal to form a U-shaped groove (3) and an inverted U-shaped groove (4), and the directions of the U-shaped grooves are opposite; the structure size and the coupling of the complementary open-ended resonant ring (1), the U-shaped groove (3), the inverted U-shaped groove (4) and the I-shaped microstrip line (2) control the bandwidth of the passband and the transmission zero point.

the I-shaped microstrip line (2) is connected with the left transmission microstrip line (5) and the right transmission microstrip line (6), the left open-circuit branch line (7) is connected with the left transmission microstrip line (5), and the right open-circuit branch line (8) is connected with the right transmission microstrip line (6). The left open branch (7) and the right open branch (8) are coupled with each other to generate a transmission zero point, so that the selectivity of the filter is improved.

The key technical difficulty of the low-pass filter with the complementary open resonant ring and the U-shaped slot defected ground is to solve the problems of the sizes and the couplings of the complementary open resonant ring, the U-shaped slot, the inverted U-shaped slot and the I-shaped microstrip line structure and determine key structural parameters influencing low-pass transmission response. The structure size and the coupling of the open-circuit branch line are accurately designed, a transmission zero point is introduced, and the selectivity of the low-pass filter is improved.

Compared with the prior art, the utility model, following advantage and beneficial effect have:

1. The utility model discloses utilize plane microstrip and defected ground technique for design flexibility, easy integration, small-size, low loss.

2. This practicality utilizes open circuit branch line coupling, introduces a plurality of transmission zeros, improves the outband rejection performance of wave filter.

Drawings

Fig. 1 is a schematic structural diagram of a low pass filter with a complementary split ring resonator and a U-slot defected ground according to the present invention;

FIG. 2 is a schematic bottom view of the dielectric substrate shown in FIG. 1;

FIG. 3 is a top schematic view of the dielectric substrate shown in FIG. 1;

Fig. 4 is a frequency response graph of an example of a complementary split ring resonator and U-slot defected ground low pass filter of the present invention.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.

As shown in fig. 1 to 4, in the low pass filter with the complementary open resonant ring and the U-shaped groove defected ground, the length and the width of a gap (1-1) in the bottom metal ground etched complementary open resonant ring (1) are 32.72mm and 0.6mm respectively, the length and the width of the gap (1-2) are 21.92mm and 0.48mm respectively, and the metal distance between the gap (1-1) and the gap (1-2) is 0.8 mm; the length and the width of the bottom metal ground etching U groove (3) are respectively 20.46mm and 0.5mm, the distance between the U groove (3) and the inverted U groove (4) is 0.5mm, and the metal distance between the gap (1-1) and the U groove (3) is 0.6 mm.

The length and the width of a minus structure in the I-shaped microstrip line (2) are respectively 6mm and 0.5mm, the length and the width of the minus structure are respectively 1.8mm and 0.3mm, the length and the width of the left transmission microstrip line (5) are respectively 6.75mm and 0.8mm, the length and the width of the left open-circuit branch line (7) are respectively 14.6mm and 0.5mm, and the distance between the left open-circuit branch line (7) and the right open-circuit branch line (8) is 0.5 mm.

In this example, Rogers 4003 was used as the dielectric substrate, which had a dielectric constant of 3.55 and a thickness of 0.508 mm.

Fig. 4 is a graph showing the frequency response of this example. The figure comprises two large curves, namely, an | S21 | and an | S11 | the curve is the transmission characteristic curve of the signal, and the curve is the reflection characteristic curve of the port, namely, the S21 | and the S11 | are all the same. As can be seen, the filter has a low voltage frequency response, a-3 dB cutoff frequency of 1.91GHz, passband attenuation within 0.15dB, return loss within the passband of greater than about 20dB, and about-20 dB out-of-band rejection from 2.05GHz to 3.93 GHz.

compared with the prior art, the utility model relates to a low pass filter of complementary opening resonant ring and U groove defect ground. The transmission characteristics and the coupling of the plane microstrip and the defected ground are utilized to generate low-pass frequency response, and the open-circuit branch lines are adopted to mutually couple to introduce transmission zero points, so that the selectivity of a pass band is improved.

The embodiments of the present invention are not limited by the above embodiments, and any other equivalent substitutions or changes without departing from the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims

1. A complementary split ring resonator and U-slot defected ground low pass filter is characterized in that: the low-pass filter comprises a three-layer structure of a top layer, a medium substrate layer and a bottom layer of metal.

The bottom layer is etched with the complementary opening resonance ring (1), the U groove (3) and the inverted U groove (4) in a metal mode. The U groove (3) and the inverted U groove (4) are in an axisymmetric structure, and the complementary split resonant ring (1) is positioned in the structure formed by the U groove (3) and the inverted U groove (4).

2. The complementary split ring resonator and U-slot defected ground low pass filter of claim 1, wherein: the main body structure of the filter is composed of a complementary open-ended resonant ring (1), a U-shaped groove (3), an inverted U-shaped groove (4) and an I-shaped microstrip line (2), and the center lines of the complementary open-ended resonant ring (1) and the I-shaped microstrip line (2) are on the same straight line.

3. A complementary split ring and U-slot defected ground low pass filter according to claim 1 or 2, wherein: the structure size and the coupling of the complementary open-ended resonant ring (1), the U-shaped groove (3), the inverted U-shaped groove (4) and the I-shaped microstrip line (2) control the bandwidth of the passband and the transmission zero point.

4. The complementary split ring resonator and U-slot defected ground low pass filter of claim 1, wherein: the left transmission microstrip line (5) and the right transmission microstrip line (6) are connected with the I-shaped microstrip line (2), the left open-circuit branch line (7) is connected with the left transmission microstrip line (5), and the right open-circuit branch line (8) is connected with the right transmission microstrip line (6). The left open branch (7) and the right open branch (8) are coupled with each other to generate a transmission zero point, so that the selectivity of the filter is improved.

5. The complementary split ring resonator and U-slot defected ground low pass filter of claim 1, wherein: the material of the dielectric substrate layer in the low-pass filter adopts Rogers 4003, and the dielectric constant of the material is 3.55.