WO2021093016A1

WO2021093016A1 - Microstrip line filter

Info

Publication number: WO2021093016A1
Application number: PCT/CN2019/120765
Authority: WO
Inventors: 赵小伟
Original assignee: 郴州世通科技有限公司
Priority date: 2019-11-12
Filing date: 2019-11-26
Publication date: 2021-05-20
Also published as: CN110931926B; BR112022009162A2; CN110931926A

Abstract

The present invention relates to a microstrip line filter, including a plurality of linearly arranged microstrip line filter units; each microstrip line filter unit includes a first microstrip line and a second microstrip line, the first microstrip line is enclosed to form an accommodating space, the first microstrip line is also provided with an opening communicating with the accommodating space, one end of the second microstrip line is located in the accommodating space and is connected to the first microstrip line, the other end of the second microstrip line passes through the opening and protrudes out of the accommodating space. The microstrip line filter has an ultra-close frequency high out-of-band rejection function, which improves the Q value of the microstrip line filter.

Description

Microstrip filter

Technical field

The present invention relates to the technical field of filtering, in particular to a microstrip line filter.

Background technique

With the continuous development of the communications industry, frequency resources will become increasingly scarce, and frequency ultra-close frequency suppression will become more urgent. For example, the outdoor unit of satellite TV signal receiving equipment tuner (Low Noise Block (LNB) is an outdoor unit necessary for the satellite signal transmission system, used for signal amplification and frequency conversion processing of the weak heart blood signal received from the satellite. The satellite tuner contains a band-pass filter to filter frequency signals. As the frequency of space signals has become denser, especially the rapid development and application of LTE (Long Term Evolution) and 5G communications, the application frequency of LTE and 5G has approached the application frequency of satellite TV signals, and many 5G countries are choosing 3.3-3.6GHz Frequency, China's satellite TV C-BAND downlink signal is in 3.7-4.2GHz, and many foreign countries or regions C-BAND satellite TV downlink frequency is used in 3.63-4.2GHz, the 5G frequency is relative to the satellite C-BAND downlink frequency. Ultra-close frequency will cause interference to the TV signal of C-BAND tuner products.

technical problem

How to better achieve strong out-of-band suppression at ultra-close frequency is a problem that needs to be solved urgently at present.

Technical solutions

Based on this, it is necessary to address the above problems and provide a microstrip line filter that can achieve strong out-of-band suppression at ultra-close frequencies.

A microstrip line filter includes a plurality of linearly arranged microstrip line filter units; each of the microstrip line filter units includes a first microstrip line and a second microstrip line, the first microstrip line The strip line is enclosed to form an accommodating space, the first microstrip line is also provided with an opening communicating with the accommodating space, and one end of the second microstrip line is located in the accommodating space and is connected to The first microstrip line is connected, and the other end of the second microstrip line passes through the opening and protrudes out of the accommodating space.

In one of the embodiments, the second microstrip line includes a vertical strip section and a horizontal strip section, one end of the vertical strip section is connected to the first microstrip line, and the other end of the vertical strip section passes through The opening is connected to the horizontal bar section, and the horizontal bar section is located outside the accommodating space.

In one of the embodiments, the vertical strip section includes a first section and a second section, one end of the first section is connected to the first microstrip line, and the other end of the first section is connected to the first section. One end of the two sections is connected, and the other end of the second section is connected to the horizontal bar section. In the arrangement direction of the plurality of microstrip line filter units, the size of the first section is larger or smaller than that of all the microstrip line filter units. State the size of the second paragraph.

In one of the embodiments, the second microstrip line is T-shaped or L-shaped.

In one of the embodiments, the first microstrip line includes a first surrounding portion and a second surrounding portion, the first surrounding portion and the second surrounding portion are connected to form the accommodating space, and the first The surrounding portion is U-shaped, and the second surrounding portion is provided at the opening and extends along the arrangement direction of the plurality of microstrip line filter units.

In one of the embodiments, there are two second surrounding parts, and the opening is located between the two second surrounding parts.

In one of the embodiments, two adjacent microstrip line filter units are arranged at intervals.

In one of the embodiments, each of the microstrip line filter units includes a first end and a second end that are opposed to each other, the opening is located at the first end, and the microstrip line In the filter unit, the direction from the first end to the second end is opposite.

In one of the embodiments, it further includes an input terminal and an output terminal, and a plurality of the microstrip line filter units are all located between the input terminal and the output terminal.

In one of the embodiments, the input terminal is connected to the microstrip line filter unit closest to it, and the output terminal is connected to the microstrip line filter unit closest to it; or the input terminal The microstrip line filter unit closest to it is arranged at intervals, and the output end is arranged at intervals to the microstrip line filter unit closest to it.

Beneficial effect

In the above-mentioned microstrip line filter, not only is the coupling between the microstrip line filter units, but also the coupling is formed between the first microstrip line through the opening and the second microstrip line in the same microstrip line filter unit. The traditional microstrip line filter, the microstrip line filter has strong out-of-band suppression function for ultra-near frequencies, and improves the Q value of the filter.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, without creative work, other drawings can be obtained based on the structure shown in these drawings.

FIG. 1 is a schematic diagram of the structure of a microstrip line filter in an embodiment;

2 is a schematic diagram of the structure of a microstrip line filter in another embodiment;

3 is a schematic structural diagram of a microstrip line filter unit in the microstrip line filter shown in FIG. 1;

4 is a schematic diagram of the structure of a first microstrip line in an embodiment;

FIG. 5 is a schematic structural diagram of a microstrip line filter in another embodiment;

Fig. 6 is an S(2,1) simulation experiment diagram of the microstrip line filter shown in Fig. 1;

Fig. 7 is the S(1,1) simulation experiment diagram of the microstrip line filter shown in Fig. 1.

Embodiments of the present invention

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention.

As shown in FIGS. 1 and 2, the microstrip line filter includes a plurality of linearly arranged microstrip line filter units 10. In this embodiment, the microstrip line filter includes 3-7 microstrip line filters. Specifically, in this embodiment, the number of microstrip filter units 10 is 5. In other embodiments, the number of microstrip filter units 10 may also be 3, 4, or 6. the above. You can customize the number of microstrip filter units according to actual needs.

A plurality of microstrip line filter units 10 have some common features. Specifically, each of the microstrip line filter units 10 includes a first microstrip line 102 and a second microstrip line 104. The first microstrip line The line 102 encloses an accommodating space 106, the first microstrip line is also provided with an opening 108 communicating with the accommodating space 106, and one end of the second microstrip line 104 is located in the accommodating space It is connected to the first microstrip line 102, and the other end of the second microstrip line passes through the opening 108 and protrudes out of the accommodating space 106.

The above-mentioned microstrip line filter is used as a band-pass filter, and its function is to allow only the set frequency range to pass and filter out other frequencies. The second microstrip line 104 is realized by a quarter-wavelength open-circuit transmission line with high and low impedance conversion, so that attenuation transmission zeros are generated at the edge of the passband, and the cutoff slope of the passband is steeper to improve the microstrip. The selectivity of the stripline filter. For the above-mentioned microstrip line filter, not only is the coupling between the microstrip line filter units 10 formed, but the first microstrip line 102 in each microstrip line filter unit 10 passes through the opening to communicate with the second microstrip line 104. A coupling is also formed between them. Compared with the traditional microstrip line filter, the microstrip line filter has a strong out-of-band suppression function for the ultra-close frequency, which improves the Q value of the microstrip line filter.

1 and 5, each of the microstrip line filter unit includes a first end 110 and a second end 120 that are oppositely disposed, and the opening 108 is located at the first end 110, and is located at two adjacent ends. In the microstrip line filter unit, the directions of the first end 110 to the second end 120 are opposite. Taking the viewing angle as shown in FIG. 5, for the first microstrip line filter unit 10 on the left, its first end 110 is located above the second end 120, and for the second microstrip line filter unit on the left For the device unit 10, the first end 110 is located below the second end 120, and so on. Of course, in different embodiments, the arrangement positions of the first end 110 and the second end 120 of the microstrip line filter unit at the same position may be the same or different. For example, in the embodiment shown in FIG. 2, for the first microstrip line filter unit 10 on the left, its first end 110 is located below the second end 120, and for the second microstrip line filter unit 10 on the left, For the microstrip line filter unit 10, the first end 110 is located above the second end 120.

1 and 4, for each microstrip line filter unit, the first microstrip line includes a first surrounding portion 1022 and a second surrounding portion 1024, the first surrounding portion 1022 and The second enclosing portion 1024 is connected to form the accommodating space 106, the first enclosing portion 1022 is U-shaped, and the second enclosing portion 1024 is provided at the opening 108 and runs along a plurality of the microstrips. The arrangement direction of the line filter unit 10 extends. The arrangement of the second surrounding portion 1024 can reduce the size of the opening, so that the microstrip line filter can better achieve the effect of suppressing the ultra-near frequency band. The extension size of the second enclosing portion can be determined according to the actual situation, so as to determine the position and size of the opening.

In the embodiment shown in FIGS. 1 and 5, each microstrip line filter unit 10 has two second surrounding parts 1024, and the opening is located between the two second surrounding parts.

In the embodiment shown in FIG. 2, there are two second surrounding parts 1024 of part of the microstrip line filter unit 10, and only one second surrounding part 1024 of the part of the microstrip line filter unit 10 is provided. More specifically, taking FIG. 2 as the viewing angle of view, in the leftmost microstrip line filter unit and the rightmost microstrip line filter unit, only one second enclosing part 1024 is provided, and in the remaining microstrip line filter unit In the stripline filter unit, there are two second surrounding parts.

It is understandable that, in some embodiments, the second surrounding portion may also be omitted.

3 and 4, the second microstrip line includes a vertical strip segment 1042 and a horizontal strip segment 1044, one end of the vertical strip segment 1042 is connected to the first microstrip line 102, and the vertical strip segment The other end of 1042 passes through the opening 108 and is connected to the horizontal bar section 1044, and the horizontal bar section 1044 is located outside the accommodating space 106. More specifically, the vertical bar section 1042 is centrally disposed in the first surrounding portion 1022, the vertical bar section 1044 extends in a direction perpendicular to the arrangement of the microstrip line filter units, and the horizontal bar section 1044 is parallel to the microstrip line filter unit. The arrangement direction extends, that is, the extending direction of the vertical strip section 1042 is perpendicular to the extending direction of the horizontal strip section 1044. While not affecting the function of the microstrip line filter to suppress the ultra-near frequency band, the positional relationship of the vertical bar section relative to the first enclosing part and the relative relationship between the vertical bar section and the horizontal bar section can be reduced as much as possible. The printing area occupied by the microstrip line filter.

In the embodiment shown in FIG. 1 and FIG. 5, the second microstrip line is T-shaped, that is, the connection position of the vertical strip section 1042 and the horizontal strip section 1044 is located between the two ends of the horizontal strip section 1044. The connecting position of the vertical bar section and the horizontal bar section may be centered on the two ends of the horizontal bar section, or the distance from one end of the horizontal bar section is small, and the distance from the other end of the horizontal bar section is relatively large.

In the embodiment shown in FIG. 2, the second microstrip line is L-shaped, that is, the vertical strip section is connected to one end of the horizontal strip section.

Furthermore, in this embodiment, in order to better perform ultra-near band suppression, the widths of different parts of the vertical stripe section are not the same. The width of the vertical stripe section mentioned here refers to the arrangement of the filter unit along the microstrip line. The size in the direction.

Specifically, referring to FIG. 3, the vertical bar segment includes a first segment 1042A and a second segment 1042B. One end of the first segment 1042A is connected to the first microstrip line 102, and the other end of the first segment 1042A It is connected to one end of the second section 1042B, and the other end of the second section 1042B is connected to the horizontal bar section 1044. It can be clearly seen from FIG. 1 that the width of the first section 1042A is greater than the width of the second section 1042B. In the embodiment shown in FIG. 2, the width of the first section is smaller than the width of the second section (not shown in the figure).

Of course, in other embodiments, the vertical strip segment may also have the same width from its end connected to the first microstrip line to its end connected to the horizontal strip segment.

With reference to Fig. 1, Fig. 2 and Fig. 5, it can be seen that the structures of multiple microstrip line filter units may be completely the same or different. The structure of each microstrip line filter unit can be determined according to the actual application of the microstrip line filter.

Referring to Figures 1, 2 and 5, the microstrip line filter further includes an input terminal 20 and an output terminal 30, and a plurality of the microstrip line filter units 10 are all located between the input terminal 20 and the output terminal 30 between.

In the embodiment shown in FIG. 1 and FIG. 5, the input end 20 and the closest microstrip line filter unit 10 are arranged at intervals, and the output end 30 and the closest microstrip line filter unit 10 are arranged at intervals. Unit 10 is arranged at intervals.

In the embodiment shown in FIG. 2, the input terminal 20 is connected to the microstrip line filter unit 10 closest to it, and the output terminal 30 is connected to the microstrip line filter unit closest to it. .

Of course, in the embodiment shown in FIGS. 1 and 5, the input terminal 20 can also be connected to the microstrip line filter unit 10 closest to it, and the output terminal 30 is connected to the closest microstrip line filter unit 10 to it. The microstrip line filter unit 10. In the embodiment shown in FIG. 2, the input terminal 20 and the closest microstrip line filter unit 10 may also be arranged at intervals, and the output terminal 30 and the closest microstrip line filter unit 10 may be arranged at intervals. The device units 10 are arranged at intervals.

Please refer to Figure 1, Figure 2 and Figure 5, adjacent microstrip line filter units 10 are arranged at intervals, that is, there is a distance between the microstrip line filter units, and the distance between the microstrip line filter units can be adjusted by The separation distance to adjust the receiving frequency bandwidth. The separation distance between different microstrip line filter units can be the same or different, and specifically can be adaptively adjusted according to actual needs.

The microstrip line filter can be applied to the ultra-close frequency filtering of different frequency bands, for example, it is suitable for the C-BAND frequency band of the outdoor unit of satellite TV signal reception, and it is also suitable for the 5G frequency band, as well as the KU-BAND frequency band and the KA-BAND frequency band. For different frequency bands, it is necessary to customize the separation distance between the microstrip line filter units and the size of the first microstrip line and the second microstrip line.

In one embodiment, the microstrip line filter is applied to the C-BAND tuner circuit configuration part of the satellite TV signal receiving outdoor unit, and is set in the tuner circuit box. The first-stage low-noise amplifier (low-noise amplifier) After the amplifier) or after the second-stage low-noise amplifier, the filtering function is mainly performed before mixing to suppress out-of-band interference signals, realize the ideal mixing of useful signals and reduce the mixing of unnecessary signals, so that the intermodulation suppression after mixing Superior, reducing interference and finally transmitting to the satellite receiver to achieve a clear and colorful TV picture. In order to improve the out-of-band suppression effect, especially for LTE and 5G signals, it has a significant out-of-band strong suppression. Using the above-mentioned microwave filters (as shown in Figures 1 and 2) can achieve strong out-of-band suppression effects, especially ultra-close frequency suppression.

In one embodiment, adjusting the line length according to the actual frequency and range in the actual application scenario can extend the application frequency, for example, it can be applied to the KU-BAND and KA-BAND frequency bands. Among them, the KU-BAND frequency band applied to the direct-broadcast satellite TV broadcasting service ranges from 10 GHz to 15 GHz, and the KA-BAND frequency band applied to the direct-broadcast satellite TV broadcasting service ranges from 18 to 28 GHz.

The frequency of the traditional C-BAND satellite is generally between 3.63-4.2GHz or 3.7~4.2GHz. The above-mentioned microstrip line filter can achieve a frequency separation of 3.7GHz relative to 3.6GHz 100MHz, and adjacent frequency suppression can reach 50dB or more. External suppression capability, 3.65GHz is relative to 3.6GHz The 50MHz frequency interval ultra-close frequency suppression achieves an out-of-band suppression capability of more than 45dB, which can completely solve the impact of LTE signals and 5G signals on C-BAND direct broadcast satellite broadcast TV signals.

Referring to FIG. 5, in one embodiment, in order to better realize the strong out-of-band suppression of the super-near frequency, the input terminal 20 and the closest microstrip line filter unit (the first microstrip line filter unit) The separation distance is set to 6-16mil (mil, mil, length unit), the separation distance between the first microstrip line filter unit and the second microstrip line filter unit is set to 16-30mil, the second The separation distance between the microstrip line filter unit and the third microstrip line filter unit is set to 18-36mil, and the distance between the third microstrip line filter unit and the fourth microstrip line filter unit The distance is set to 18-36mil, the separation distance between the fourth microstrip line filter unit and the fifth microstrip line filter unit is set to 16-30mil, the fifth microstrip line filter unit and the output end 30 The separation distance between is set to 6-16mil.

As shown in FIG. 6 and FIG. 7, it is a simulation schematic diagram of a microstrip line filter used in a satellite TV signal receiving outdoor unit C-BAND tuner in an embodiment, the abscissa represents the insertion loss, and the ordinate represents the frequency; Fig. 6 is a simulation diagram obtained on the basis of S(2,1), and Fig. 7 is a simulation diagram obtained on the basis of S(1,1). S(2,1) represents the transmission coefficient, and S(1,1) represents the self-reflection coefficient, so the simulation images obtained by S(2,1) and S(1,1) are just the opposite. Refer to m5 (3.6GHz, -61.2996dB) and m6 (3.65GHz, -14.2778dB), the abscissa difference is 50MHz, the ordinate difference is more than 47dB, the coordinates of m5 and m7 in the figure, the abscissa difference is 100MHz, and the ordinate difference is more than 55dB.

As shown in Figures 6 and 7, it can be clearly seen that the microstrip line filter has strong ultra-close frequency suppression. The ultra-close frequency 50MHz interval suppression can reach more than 45dB, and the ultra-close frequency 100MHz frequency interval suppression can reach more than 50dB, which is extremely superior. The filtering index. In addition, the microstrip filter can be made by PCB circuit microstrip line to achieve ultra-close frequency interference suppression, low cost, and simpler and more efficient mass production.

The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be It is considered as the range described in this specification.

The above-mentioned embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation to the patent scope of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can be made, and these all fall within the protection scope of this application. Therefore, the scope of protection of the patent of this application shall be subject to the appended claims.

Claims

A microstrip line filter, characterized in that it comprises a plurality of linearly arranged microstrip line filter units;

Each of the microstrip line filter units includes a first microstrip line and a second microstrip line, the first microstrip line is enclosed to form an accommodating space, and the first microstrip line is also provided with The opening connected to the accommodating space, one end of the second microstrip line is located in the accommodating space and connected to the first microstrip line, and the other end of the second microstrip line passes through the accommodating space. The opening extends out of the accommodating space.
The microstrip line filter according to claim 1, wherein the second microstrip line includes a vertical strip segment and a horizontal strip segment, and one end of the vertical strip segment is connected to the first microstrip line, The other end of the vertical bar section passes through the opening and is connected to the horizontal bar section, and the horizontal bar section is located outside the accommodating space.
The microstrip line filter according to claim 2, wherein the vertical strip section includes a first section and a second section, one end of the first section is connected to the first microstrip line, and the The other end of the first section is connected to one end of the second section, and the other end of the second section is connected to the horizontal bar section. In the arrangement direction of the plurality of microstrip line filter units, so The size of the first section is larger or smaller than the size of the second section.
The microstrip line filter according to claim 2, wherein the second microstrip line is T-shaped or L-shaped.
The microstrip line filter according to claim 1, wherein the first microstrip line includes a first enclosing part and a second enclosing part, and the first enclosing part and the second enclosing part are connected to form In the accommodating space, the first enclosing portion is U-shaped, and the second enclosing portion is provided at the opening and extends along the arrangement direction of the plurality of microstrip line filter units.
The microstrip line filter according to claim 5, wherein there are two second enclosing parts, and the opening is located between the two second enclosing parts.
The microstrip line filter according to claim 1, wherein two adjacent microstrip line filter units are arranged at intervals.
The microstrip line filter according to claim 1, wherein each of the microstrip line filter units comprises a first end and a second end that are oppositely arranged, and the opening is located at the first end and In the two adjacent microstrip line filter units, the directions from the first end to the second end are opposite.
The microstrip line filter according to claim 1, further comprising an input terminal and an output terminal, and a plurality of the microstrip line filter units are all located between the input terminal and the output terminal.
The microstrip line filter according to claim 1, wherein the input terminal is connected to the microstrip line filter unit closest to it, and the output terminal is connected to the microstrip line filter unit closest to it. Line filter unit; or

The input end and the closest microstrip line filter unit are arranged at intervals, and the output end and the closest microstrip line filter unit are arranged at intervals.