CN113113742A

CN113113742A - Transverse signal interference double-broadband band-pass filter

Info

Publication number: CN113113742A
Application number: CN202110338014.4A
Authority: CN
Inventors: 熊阳
Original assignee: Southwest Electronic Technology Institute No 10 Institute of Cetc
Current assignee: CETC 10 Research Institute; Southwest Electronic Technology Institute No 10 Institute of Cetc
Priority date: 2021-03-30
Filing date: 2021-03-30
Publication date: 2021-07-13

Abstract

The invention discloses a double-broadband band-pass filter for transverse signal interference, which aims to realize broadband, controllable passband, low insertion loss, high out-of-band rejection and excellent standing wave. The invention is realized by the following technical scheme: a copper-clad grounding plate and a microstrip circuit etched on a dielectric substrate are adopted. The microstrip circuit comprises a first short-circuit inverted L-shaped microstrip branch line connected to an input port feeder line and combined with an input port feeder line connection point of a first microstrip connection line and a third microstrip connection line on the left side at right angle, a second short-circuit inverted L-shaped microstrip branch line connected to an output port feeder line and combined with a second microstrip connection point and a fourth microstrip connection point of a right side output port feeder line at right angle, a U-shaped microstrip connection line attached to the inner sides of the first microstrip connection line and the fourth microstrip connection line, a resonator loaded on a T-shaped branch line perpendicular to the middle of the U-shaped microstrip connection line, and a first open-circuit branch line horizontally connected to the bottom of the third microstrip connection line and a second open-circuit branch line horizontally connected to the lower end face of the fourth microstrip connection line to form a pair of parallel coupling.

Description

Transverse signal interference double-broadband band-pass filter

Technical Field

The invention relates to a microwave device applied to the technical field of wireless communication, in particular to a double-broadband band-pass filter based on transverse signal interference.

Background

With the rapid development of technologies such as 5G communication, artificial intelligence, virtual reality and the like, the contradiction between limited spectrum resources and application requirements is increasingly prominent, and the traditional narrowband communication system cannot adapt to the actual requirements of the application scenes due to small transmission capacity and low transmission rate, so that the wireless broadband technology is more and more emphasized by people. In order to meet the urgent demands of users for different communication modes and high transmission rates, modern communication systems need to combine multiband technology and wideband technology, and therefore, wideband multi-band filters are produced. In the RF front-end system, the filter is used to suppress the out-of-band spurious signals and noise level, and simultaneously, the useful signals can pass through almost without loss, thereby meeting the signal-to-noise ratio required by the communication system. As one of the key devices in the rf front end of a communication system, the performance of the filter directly affects the quality of the entire communication system. In order to meet the requirement of miniaturization of microwave integrated circuits, the filter is required to have good frequency response, small volume, light weight, convenience for planar integration and the like. Although a large number of dual-band filters have been reported, these filters do not satisfy the development requirements of information technology for broadband. The existing double-broadband filter technology has the following defects and disadvantages: the relative bandwidth FBW of the pass band is generally about 10-20%, and the harsh requirements that the FBW of the two pass bands is more than 40% cannot be met simultaneously; secondly, the filter has low passband isolation and poor selectivity; the stop band rejection level of the filter is low; the insertion loss is large.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a double-broadband filter based on a transverse signal interference mechanism, which has the advantages of simple structure, wide frequency band, controllable passband, low insertion loss, high out-of-band rejection and excellent standing wave.

The above object of the present invention can be achieved by the following technical solutions: a dual wideband bandpass filter for cross-signal interference, comprising: the microstrip circuit comprises a dielectric substrate with a copper-clad grounding plate and a microstrip circuit etched on the surface of the dielectric substrate, and is characterized in that: the microstrip circuit comprises a first short-circuit inverted L-shaped microstrip branch line 2 connected to an input port feeder line 1 and combined with a connection point of a first microstrip connection line 3 on the left side and a third microstrip connection line 8 at a right angle, a second short-circuit inverted L-shaped microstrip branch line 6 connected to a connection point of a second microstrip connection line 5 on a right side output port feeder line 12 and combined with a connection point of a fourth microstrip connection line 11 at a right angle, a U-shaped microstrip connection line 4 attached to the inner sides of the first microstrip connection line 3 and the second microstrip connection line 5, a resonator 7 loaded on a T-shaped branch perpendicular to the middle of the U-shaped microstrip connection line 4, and a first open-circuit branch line 9 in butt joint with the bottom of the third microstrip connection line 8 and a second open-circuit branch line 10 in butt joint with the lower end face of the fourth microstrip connection line 11 to form a pair of parallel coupling lines.

Compared with the prior art, the invention has the following beneficial effects:

according to the double-broadband band-pass filter designed based on the transverse filter theory, an input signal can be divided into a plurality of transmission paths by introducing transverse signal interference, after transmission of a plurality of different paths, transmission signals of different transmission paths can generate phase difference, so that output signals can generate in-phase superposition or opposite phase cancellation, a plurality of transmission zeros are introduced into a stop band, the isolation between the pass bands and the stop band suppression level are improved, and a steep sideband characteristic is obtained; the relative bandwidth of the two pass bands of the filter can reach more than 40 percent, and the application of ultra wide band multi-pass band is met; a pair of parallel coupling lines is adopted between the input/output ports, and the bandwidth of the first passband can be changed by increasing or decreasing the distance between the parallel coupling lines, so that the controllability of the passband bandwidth is realized; the smaller the parallel coupled line spacing, the larger the bandwidth and vice versa.

The filter provided by the invention has very simple circuit structure, and simultaneously adopts the high-performance microwave medium substrate Rogers 5880, so that the filter has extremely low insertion loss;

by utilizing the interference characteristics of the signals of the two transmission paths, a plurality of transmission zeros are introduced into the stop band, thereby improving the upper stop band characteristic of the filter, which realizes high out-of-band rejection.

Drawings

FIG. 1 is a dual broadband bandpass filter for transversal signal interference of the present invention;

fig. 2 is a simulation curve of the S-parameter of the double wideband bandpass filter for transversal signal interference according to the present invention.

In the figure: 1. the microstrip line comprises an input port feeder line, 2, a first short-circuit inverted L-shaped microstrip branch line, 3, a first microstrip connecting line, 4, a U-shaped microstrip connecting line, 5, a second microstrip connecting line, 6, a second short-circuit inverted L-shaped microstrip branch line, 7, a T-shaped branch loading resonator, 8, a third microstrip connecting line, 9, a first open-circuit branch line, 10, a second open-circuit branch line, 11, a fourth microstrip connecting line and 12, an output port feeder line.

The invention will be further explained with reference to the drawings.

Detailed Description

See fig. 1. In a preferred embodiment described below, a dual wideband bandpass filter for cross signal interference, comprises: a dielectric substrate with a copper-clad ground plate and a microstrip circuit etched on the surface of the dielectric substrate. The microstrip circuit comprises a first short-circuit inverted L-shaped microstrip branch line 2 connected to an input port feeder line 1 and combined with a connection point of a first microstrip connection line 3 on the left side and a third microstrip connection line 8 at a right angle, a second short-circuit inverted L-shaped microstrip branch line 6 connected to a connection point of a second microstrip connection line 5 on a right side output port feeder line 12 and combined with a connection point of a fourth microstrip connection line 11 at a right angle, a U-shaped microstrip connection line 4 attached to the inner sides of the first microstrip connection line 3 and the second microstrip connection line 5, a resonator 7 loaded on a T-shaped branch perpendicular to the middle of the U-shaped microstrip connection line 4, and a first open-circuit branch line 9 in butt joint with the bottom of the third microstrip connection line 8 and a second open-circuit branch line 10 in butt joint with the lower end face of the fourth microstrip connection line 11 to form a pair of parallel coupling lines.

Further, the input port feed line 1 and the output port feed line 12 are both 50 ohm matching ports.

Further, the first short-circuit inverted L-shaped microstrip branch line 2, the first microstrip connecting line 3, the U-shaped microstrip connecting line 4, the second microstrip connecting line 5, the second short-circuit inverted L-shaped microstrip branch line 6, and the T-shaped branch loading resonator 7 form a first transmission path of the lateral interference circuit.

Furthermore, the third microstrip connection line 8, the first open-circuit stub 9, the second open-circuit stub 10, and the fourth microstrip connection line 11 form a second transmission path of the transversal interference circuit.

Further, the loading position of the T-shaped branch loading resonator 7 is located at the center of the U-shaped microstrip connecting line 4.

Furthermore, the dielectric substrate is Rogers 5880, the relative dielectric constant of the dielectric substrate is 2.2, the thickness of the dielectric substrate is 0.508mm, and the loss tangent value of the dielectric substrate is 0.0009.

Fig. 2 shows a simulation curve of S parameter of the dual broadband bandpass filter for the transversal signal interference, and it can be seen that the center frequency of the dual broadband filter is respectively located at 2.08GHz and 5.68GHz, the 3-dB relative bandwidth is respectively 48% and 41.9%, the minimum insertion loss is respectively 0.14dB and 0.28dB, and the out-of-band rejection level of the filter can be as high as above 29 dB.

The above is a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions made by those skilled in the art based on the innovative concept of the present invention are within the scope of the present invention.

Claims

1. A dual wideband bandpass filter for cross-signal interference, comprising: the microstrip circuit comprises a dielectric substrate with a copper-clad grounding plate and a microstrip circuit etched on the surface of the dielectric substrate, and is characterized in that: the microstrip circuit comprises a first short-circuit inverted L-shaped microstrip branch line (2) which is connected with an input port feeder line (1) and is combined with the connection point of a first microstrip connection line (3) on the left side and a third microstrip connection line (8) at right angle, a second short-circuit inverted L-shaped microstrip branch line (6) which is connected with an output port feeder line on the right side (12) and is combined with the connection point of a second microstrip connection line (5) and a fourth microstrip connection line (11) on the right side at right angle, a U-shaped microstrip connecting line (4) attached to the inner sides of the first microstrip connecting line (3) and the second microstrip connecting line (5), a T-shaped branch loaded resonator (7) vertical to the middle part of the U-shaped microstrip connecting line (4), and a first open-circuit branch line (9) which is connected with the bottom of the third microstrip connecting line (8) in a butt joint mode and a second open-circuit branch line (10) which is connected with the lower end face of the fourth microstrip connecting line (11) in a butt joint mode form a pair of parallel coupling lines.

2. The dual wideband bandpass filter for transversal signal interference according to claim 1, characterized in that: the input port feeder (1) and the output port feeder (12) are both 50 ohm matching ports.

3. The dual wideband bandpass filter for transversal signal interference according to claim 1, characterized in that: the first short-circuit inverted L-shaped micro-strip branch line (2), the first micro-strip connecting line (3), the U-shaped micro-strip connecting line (4), the second micro-strip connecting line (5), the second short-circuit inverted L-shaped micro-strip branch line (6) and the T-shaped branch loading resonator (7) form a first transmission path of the transverse interference circuit.

4. The dual wideband bandpass filter for transversal signal interference according to claim 1, characterized in that: the third microstrip connecting line (8), the first open-circuit branch line (9), the second open-circuit branch line (10) and the fourth microstrip connecting line (11) form a second transmission path of the transverse interference circuit.

5. The dual wideband bandpass filter for transversal signal interference according to claim 1, characterized in that: the dielectric substrate is Rogers 5880, the relative dielectric constant of the dielectric substrate is 2.2, the thickness of the dielectric substrate is 0.508mm, and the loss tangent value of the dielectric substrate is 0.0009.

6. The dual wideband bandpass filter for transversal signal interference according to claim 1, characterized in that: the loading position of the T-shaped branch loading resonator (7) is positioned at the center of the U-shaped microstrip connecting line (4).