阅读说明：本技术 微带滤波器 (Microstrip filter ) 是由 陈文宽 于 2020-12-30 设计创作，主要内容包括：本申请涉及滤波器,提供了一种微带滤波器,设置于电路板上,所述微带滤波器包括呈容性的第一微带器件和呈感性的第二微带器件,所述第一微带器件和所述第二微带器件相串联或相并联；所述第一微带器件包括多块金属板,相邻的所述金属板之间可通过连接导体电连接；所述第二微带器件为平面螺旋状或蛇形结构,所述第二微带器件中间隔相邻的微带线段之间可通过短接导体短接。可以通过连接导体并接金属板的数量来调节第一微带器件的电容参数；可以通过短接导体短接径向相邻的微带线段调节第二微带器件的电感参数,因此,可使得微带滤波器的工作频率可动态调节。(The application relates to a filter, and provides a microstrip filter which is arranged on a circuit board and comprises a first microstrip device and a second microstrip device, wherein the first microstrip device and the second microstrip device are capacitive and inductive, and are connected in series or in parallel; the first microstrip device comprises a plurality of metal plates, and adjacent metal plates can be electrically connected through a connecting conductor; the second microstrip device is of a planar spiral or snake-shaped structure, and the adjacent microstrip line segments in the second microstrip device can be in short circuit through a short-circuit conductor. The capacitance parameter of the first microstrip device can be adjusted by connecting the conductors and connecting the number of the metal plates; inductance parameters of the second microstrip device can be adjusted by short-circuiting radially adjacent microstrip line segments by the short-circuit conductor, so that the working frequency of the microstrip filter can be dynamically adjusted.)

1. A microstrip filter is arranged on a circuit board, the circuit board comprises a first conducting layer and a second conducting layer opposite to the first conducting layer, and the microstrip filter is characterized by comprising a first microstrip device in a capacitive state and a second microstrip device in an inductive state, wherein the first microstrip device and the second microstrip device are connected in series or in parallel;

the first microstrip device comprises a plurality of metal plates arranged on the first conducting layer and the second conducting layer, the metal plates arranged on the first conducting layer and the metal plates arranged on the second conducting layer are in one-to-one correspondence and mutually form a capacitor, and the adjacent metal plates can be electrically connected through a connecting conductor;

the second microstrip device is of a planar spiral structure or a snake-shaped routing structure, and adjacent microstrip line segments in the second microstrip device can be in short circuit through a short circuit conductor.

2. The microstrip filter of claim 1 wherein the second microstrip device is a planar helical structure comprising:

the first via hole is formed in the circuit board;

the first microstrip line is arranged on the first conducting layer, one end of the first microstrip line is connected with the first via hole, the first microstrip line is wound outwards at intervals by taking the first via hole as a starting point to form a planar spiral structure, and the other end of the first microstrip line is used for inputting/outputting signals; and

the second microstrip line is arranged on the second conducting layer, one end of the second microstrip line is connected with the first via hole, and the other end of the second microstrip line is used for inputting/outputting signals;

in the first microstrip line, radially adjacent microstrip line segments can be in short circuit through the short-circuit conductor.

3. The microstrip filter of claim 2 further comprising:

the second via hole is formed in the circuit board and located outside the first microstrip line, and the other end of the second microstrip line is connected with the second via hole;

and the third microstrip line is arranged on the first conducting layer and positioned outside the first microstrip line, one end of the third microstrip line is connected with the second via hole, and the other end of the third microstrip line is used for inputting/outputting signals.

4. The microstrip filter of claim 1 wherein the shorting conductor, the connecting conductor are solder or bond wires.

5. The microstrip filter of claim 3 wherein the second microstrip line is elongated; the third microstrip line is strip-shaped.

6. The microstrip filter of any of claims 1 to 5 wherein the first microstrip device comprises:

the first metal plate and the at least one second metal plate are arranged on the first conducting layer at intervals;

the first connecting end is connected with the first metal plate;

the third metal plate and the at least one fourth metal plate are arranged on the second conducting layer at intervals; and wherein the first metal plate is directly opposite the third metal plate, and each of the second metal plates is directly opposite the fourth metal plate;

a second connection end connected to the second metal plate; and

a ground conductor;

the first metal plate and the adjacent second metal plate, the adjacent two second metal plates, the third metal plate and the adjacent fourth metal plate, the adjacent two fourth metal plates, the second metal plate and the ground conductor, and the fourth metal plate and the ground conductor may be electrically connected through the connecting conductor.

7. The microstrip filter of claim 6 wherein the ground conductor comprises a first ground plate disposed on the first conductive layer and spaced apart from the first and second plates.

8. The microstrip filter of claim 7 wherein the ground conductor comprises a second ground plate disposed on the second conductive layer and spaced apart from the third and fourth plates.

9. The microstrip filter of claim 6 wherein the first metal plate, the at least one second metal plate, the third metal plate and the at least one fourth metal plate are polygonal, circular or elliptical.

10. The microstrip filter according to claim 6 wherein the first connection terminal and the second connection terminal are strip microstrip lines; the width of the strip microstrip line is smaller than the width or the length of any one of the first metal plate, the second metal plate, the third metal plate and the fourth metal plate.

Technical Field

The application belongs to the technical field of filters, and particularly relates to a microstrip filter.

Background

The filter is a common device in the fields of electronics and communication, and is divided into an integrated filter, a discrete device filter and a conventional microstrip filter at present, wherein the integrated filter has small size and good performance, but has higher cost, great development and self-control difficulty and generally unmovable working frequency; the cost of the discrete device filter is moderate, the debugging is more flexible, however, the circuit consistency is influenced by the consistency of the device, and the working frequency can not be dynamically adjusted generally; the conventional microstrip filter has low cost and can be designed autonomously, but the working frequency cannot be adjusted dynamically.

Disclosure of Invention

The application aims to provide a microstrip filter, and aims to solve the problem that the working frequency of a traditional filter cannot be dynamically adjusted.

A first aspect of an embodiment of the present application provides a microstrip filter, disposed on a circuit board, where the circuit board includes a first conductive layer and a second conductive layer opposite to the first conductive layer, and the microstrip filter includes a capacitive first microstrip device and an inductive second microstrip device, where the first microstrip device and the second microstrip device are connected in series or in parallel;

the first microstrip device comprises a plurality of metal plates arranged on the first conducting layer and the second conducting layer, the metal plates arranged on the first conducting layer and the metal plates arranged on the second conducting layer are in one-to-one correspondence and mutually form a capacitor, and the adjacent metal plates can be electrically connected through a connecting conductor;

the second microstrip device is of a planar spiral structure or a snake-shaped routing structure, and adjacent microstrip line segments in the second microstrip device can be in short circuit through a short circuit conductor.

In one embodiment, the second microstrip device comprises:

the first via hole is formed in the circuit board;

the first microstrip line is arranged on the first conducting layer, one end of the first microstrip line is connected with the first via hole, the first microstrip line is wound outwards at intervals by taking the first via hole as a starting point to form a planar spiral structure, and the other end of the first microstrip line is used for inputting/outputting signals; and

the second microstrip line is arranged on the second conducting layer, one end of the second microstrip line is connected with the first via hole, and the other end of the second microstrip line is used for inputting/outputting signals;

in the first microstrip line, radially adjacent microstrip line segments can be in short circuit through the short-circuit conductor.

In one embodiment, the method further comprises the following steps:

the second via hole is formed in the circuit board and located outside the first microstrip line, and the other end of the second microstrip line is connected with the second via hole;

and the third microstrip line is arranged on the first conducting layer and positioned outside the first microstrip line, one end of the third microstrip line is connected with the second via hole, and the other end of the third microstrip line is used for inputting/outputting signals.

In one embodiment, the short-circuit conductor and the connecting conductor are solder or bonding wires.

In one embodiment, the second microstrip line is a strip; the third microstrip line is strip-shaped.

In one embodiment, the first microstrip device comprises:

the first metal plate and the at least one second metal plate are arranged on the first conducting layer at intervals;

the first connecting end is connected with the first metal plate;

the third metal plate and the at least one fourth metal plate are arranged on the second conducting layer at intervals; and wherein the first metal plate is directly opposite the third metal plate, and each of the second metal plates is directly opposite the fourth metal plate;

a second connection end connected to the second metal plate; and

a ground conductor;

the first metal plate and the adjacent second metal plate, the adjacent two second metal plates, the third metal plate and the adjacent fourth metal plate, the adjacent two fourth metal plates, the second metal plate and the ground conductor, and the fourth metal plate and the ground conductor may be electrically connected through the connecting conductor.

In one embodiment, the grounding conductor includes a first grounding metal plate, and the first grounding metal plate is disposed on the first conductive layer and spaced apart from the first metal plate and the second metal plate.

In one embodiment, the grounding conductor includes a second grounding metal plate, and the second grounding metal plate is disposed on the second conductive layer and spaced apart from the third metal plate and the fourth metal plate.

In one embodiment, the first metal plate, the at least one second metal plate, the third metal plate and the at least one fourth metal plate are polygonal, circular or elliptical.

In one embodiment, the first connection end and the second connection end are strip-shaped microstrip lines; the width of the strip microstrip line is smaller than the width or the length of any one of the first metal plate, the second metal plate, the third metal plate and the fourth metal plate.

The microstrip filter is provided with a first microstrip device and a second microstrip device, wherein the first microstrip device is formed by coupling metal plates arranged on different layers of a circuit board, and the capacitance parameter of the first microstrip device can be adjusted by connecting a conductor and connecting the number of the metal plates in parallel; the second microstrip device is formed by a plane spiral structure arranged on the circuit board, and inductance parameters of the second microstrip device can be adjusted by short-circuiting radially adjacent microstrip line segments through the short-circuit conductor, so that the working frequency of the microstrip filter can be dynamically adjusted.

Drawings

Fig. 1 is a schematic structural diagram of a first conductive layer of a microstrip device according to an embodiment of the present disclosure;

fig. 2 is a schematic structural diagram of a second conductive layer of a microstrip device according to an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of another first embodiment of a microstrip device provided in the present application;

fig. 4 is a schematic structural diagram of another second microstrip device embodiment provided in the present application;

fig. 5 is a schematic structural diagram of another second microstrip device embodiment provided in the present application;

fig. 6 is a schematic structural diagram of a first embodiment of a microstrip filter according to the present application;

fig. 7 is a schematic structural diagram of a second embodiment of a microstrip filter according to the present application.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, refer to an orientation or positional relationship illustrated in the drawings for convenience in describing the present application and to simplify description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

Referring to fig. 1 and fig. 2, fig. 1 shows a schematic diagram of a first conductive layer structure of a microstrip device provided in an embodiment of the present application, and fig. 2 shows a schematic diagram of a second conductive layer structure of the microstrip device provided in the embodiment of the present application, and for convenience of description, only the portions related to the embodiment are shown, and detailed descriptions are as follows:

the microstrip device 10 is arranged on a circuit board, the circuit board comprises a first conducting layer and a second conducting layer opposite to the first conducting layer, and the microstrip device 10 comprises a first metal plate 11 and at least one second metal plate 12 which are arranged on the first conducting layer at intervals; and a first connection end 21 connected to the first metal plate 11; a third metal plate 13 and at least one fourth metal plate 14 which are arranged on the second conductive layer at intervals; and a second connection end 22 connected to the second metal plate 12; and a ground conductor 30. Wherein, the first connecting end 21 and the second connecting end 22 are not opposite to each other in dislocation and the extending directions are opposite.

The first metal plate 11 and the third metal plate 13 are opposite to each other to form a first capacitive unit, and each of the second metal plates 12 and the fourth metal plate 14 are opposite to each other to form a second capacitive unit. The first metal plate 11 and the adjacent second metal plate 12, the adjacent two second metal plates 12, the third metal plate 13 and the adjacent fourth metal plate 14, the adjacent two fourth metal plates 14, the second metal plate 12 and the ground conductor 30, and the fourth metal plate 14 and the ground conductor 30 may be electrically connected by the connection conductor 40.

The microstrip device 10 is a 2-port network, exhibiting high-pass filtering characteristics; assuming that the Circuit Board is a Printed Circuit Board (PCB), the first conductive layer and the second conductive layer are TOP layer and BOTTOM layer of the PCB respectively. It is to be understood that the ground conductor 30 is not limited to the structural form, and may be a microstrip line surrounding a metal plate, a ground pad, or the like.

When one of the second capacitive elements is connected to the ground conductor 30 via the connection conductor 40, the connection conductor 40 between the second capacitive element and the adjacent first or second capacitive element is disconnected and the microstrip device 10 is reduced in capacitance.

When one of the second capacitive elements switches on the connection conductor 40 between the adjacent first capacitive element or second capacitive element, and switches off the connection conductor 40 between the second capacitive element and the ground conductor 30, the microstrip device 10 increases in capacitance.

The connecting conductor 40 is solder or bonding wire, so that different sizes of each capacitive unit correspond to different capacitive values, and the larger the size is, the larger the capacitive value is, such as adjusting the area or shape of a metal plate. Wherein, the first metal plate 11, the second metal plate 12, the third metal plate 13 and the fourth metal plate 14 are polygonal, circular or elliptical. In addition, turning on different capacitive elements may adjust the capacitance of the microstrip device 10.

Furthermore, the capacitance of the microstrip device 10 can be adjusted by controlling the on-off of the grounding tin-scribing pad (the connecting conductor 40) and the on-off of the capacitive unit tin-scribing pad (the connecting conductor 40), so that the high-pass filtering working frequency of the device can be adjusted.

In one embodiment, the grounding conductor 30 includes a first grounding metal plate 31, and the first grounding metal plate 31 is disposed on the first conductive layer and spaced apart from the first metal plate 11 and the second metal plate 12. The first and second metal plates 11 and 12 may be connected to the first ground metal plate 31 through the connection conductor 40, and the third and fourth metal plates 13 and 14 may be connected to the first ground metal plate 31 through vias. In another embodiment, the grounding conductor 30 includes a second grounding metal plate 32, the second grounding metal plate 32 is disposed on the second conductive layer and spaced apart from the third metal plate 13 and the fourth metal plate 14, so that the third metal plate 13 and the fourth metal plate 14 can also be grounded through the second grounding metal plate 32, thereby omitting the via.

In one embodiment, the first connection end 21 and the second connection end 22 are strip-shaped microstrip lines for inputting/outputting electrical signals. The width of the strip microstrip line is smaller than the width or length of any one of the first metal plate 11, the second metal plate 12, the third metal plate 13 and the fourth metal plate 14, and the strip microstrip line can exhibit inductive characteristics.

Two second metal plates 12 are respectively positioned at two sides of the first metal plate 11; the number of the fourth metal plates 14 is two, and the two fourth metal plates are respectively located at two sides of the third metal plate 13, so that two second capacitive units are formed.

It can be understood that a single capacitive unit can introduce a capacitive reactance value, and the specific capacitive reactance value is related to the thickness of the PCB, the size of the capacitive unit and the electrical characteristics of the PCB board, and has different capacitive reactance values in different working frequency bands. The larger the area of the capacitive cell, the larger the capacitance, and the smaller the capacitive reactance value (capacitive reactance Xc — 1/2 pi fc).

Example (c): capacitive unit formed by rectangular metal plate, PCB plate thickness is 1mm, FR-4 medium is adopted

In another example, the capacitive cell sizes are all 5mm by 5 mm. When different numbers of capacitive cells are shorted by a scribe pad, different capacitance values are obtained. The more capacitive elements, the larger the capacitance, the smaller the capacitive reactance value (capacitive reactance Xc — 1/2 pi fc). (here, 4 capacitive pads and 2 solder points are only examples, and the number of the capacitive pads and the number of the solder points can be increased or decreased according to the requirement)

Example (c): the thickness of the PCB board is 1mm, FR-4 medium is adopted, and the size of a capacitive unit is

Therefore, the capacitive reactance value of the capacitive unit is related to the area and specific frequency of the metal patch; whether the capacitive units are connected or not is adjusted through the on-off of the tin scraping welding disc, so that the capacitance of the whole device can be adjusted; the specific capacitive reactance values of different structures can be accurately modeled and confirmed by means of simulation software, and the two sections only list specific two conditions. The size of the capacitive units, the number of the tin points and the positions of the tin points can be selected according to requirements

Referring to fig. 3 and fig. 4, a schematic structural diagram of another microstrip device 100 provided in the embodiment of the present application is shown, and for convenience of description, only the portions related to the embodiment are shown, which are detailed as follows:

this microstrip device 100 sets up on the circuit board, and the circuit board includes first conducting layer and the second conducting layer relative with first conducting layer, and microstrip device 100 includes: the first microstrip line 120 is disposed on the first conductive layer, and is bent outward at intervals to form a planar spiral structure or a serpentine routing structure with one end as a starting point, and in the first microstrip line 120, adjacent microstrip line segments at intervals can be short-circuited through the short-circuit conductor 140.

The microstrip device 100 is a 2-port network, exhibits low-pass filtering characteristics, and is short-circuited by a short-circuit conductor 140 between microstrip line segments of the first microstrip line 120 which are spaced and adjacent (wherein, the planar spiral structure is radially adjacent, and the serpentine routing structure is adjacent in one direction) to adjust inductance parameters. Assuming that the Circuit Board is a Printed Circuit Board (PCB), the first conductive layer and the second conductive layer are TOP layer and BOTTOM layer of the PCB respectively.

Referring to fig. 3, in one embodiment, the first microstrip line 120 is a planar spiral structure, and the microstrip device 100 includes a first via 110, a first microstrip line 120, and a second microstrip line 130 (shown by dotted lines in fig. 3 and disposed on the second conductive layer) disposed on the circuit board; the first microstrip line 120 is disposed on the first conductive layer, one end of the first microstrip line 120 is connected to the first via hole 110, and the first microstrip line 120 is wound outwards at intervals to form a planar spiral structure with the first via hole 110 as a starting point, and the other end of the first microstrip line 120 is used for inputting/outputting signals; the second microstrip line 130 is disposed on the second conductive layer, one end of the second microstrip line 130 is connected to the first via hole 110, and the other end is used for inputting/outputting signals; in the first microstrip line 120, radially adjacent microstrip line segments can be shorted by the shorting conductor 140. In this embodiment, one of the ports is in the first conductive layer and the other port is in the second conductive layer.

Referring to fig. 5, in another embodiment, the microstrip device 100 further includes a second via 150 and a third microstrip line 160.

The second via hole 150 is formed in the circuit board and located outside the first microstrip line 120, and the other end of the second microstrip line 130 is connected to the second via hole 150; the third microstrip line 160 is disposed on the first conductive layer and located outside the first microstrip line 120, one end of the third microstrip line 160 is connected to the second via 150, and the other end is used for inputting/outputting signals. So that both ports of the microstrip device 100 are located in the first conductive layer. The first microstrip line 120 in fig. 4 is a serpentine trace structure, and both ports of the microstrip device 100 are located in the first conductive layer.

The first microstrip line 120 adopts a planar spiral structure to realize the inductive characteristic of the circuit, which can also be called as an inductive trace. The radius, length, and number of turns of the winding trace of the first microstrip line 120 can be selected according to actual requirements. The longer the inductive wire is, the larger the inductive value of the device is, and the required inductive value can be achieved by selecting inductive wires with different radiuses, lengths and turns.

The short-circuit conductor 140 between radially adjacent microstrip line segments is open, and the inductance (inductance value) is then at a maximum. When one or more short-circuit conductors 140 are short-circuited, the current path is shortened according to the rule of the shortest current path, and the inductance of the microstrip device 100 is reduced. By selecting different positions and different numbers of the on-off schemes of the short-circuited conductor 140, the inductance of the device can be adjusted. The short-circuit conductor 140 is solder or a bonding wire, so that the inductance of the microstrip device 100 can be adjusted by setting inductive routing wires with different sizes, controlling the on-off of a solder-scribing pad (the short-circuit conductor 140) and realizing the adjustment of the working frequency of the low-pass filtering of the device.

Wherein, the line width of the first microstrip line 120 is 0.05 mm-2 mm; the distance between the radially adjacent microstrip line segments is 0.1 mm-5 mm; the second microstrip line 130 is a long strip; the third microstrip line 160 is a long strip.

Inductive reactance values can be introduced into the inductive wiring, specifically, the introduced inductive reactance values are related to the thickness of the PCB, the wiring length of the inductive reactance units, the number of turns of the wiring and the electrical characteristics of the PCB, and different inductive reactance values exist in different working frequency bands. The longer the trace length of the inductive unit, the larger the inductance, and the inductive reactance value (inductive reactance X)_L2 pi fL) is larger.

Example (c): the thickness of the PCB board is 1mm, and FR-4 medium is adopted

The bent inductive trace is inductive, so that when the inductive unit trace is short-circuited through a short-circuit conductor 140, the effective current path of the inductive unit is reduced, and meanwhile, the short-circuited part is in a ring, so that the capacitance of the inductive unit is increased, and therefore, the reactance characteristics of the inductive unit can be dynamically adjusted through short-circuits at different numbers and different positions of the short-circuit conductor 140.

In one example, there are 3 solder bumps (positions set by the short-circuit conductor 140) on the first microstrip line 120, and the reactance parameters and the on-off relationship of each solder bump are shown in the following table:

it is understood that the inductive trace shape can be a variety of shapes, including but not limited to a square ring, a circular ring, a rectangular ring, an elliptical ring, a triangular ring, a serpentine trace, etc.; the inductive reactance value of the inductive routing is related to the line width, line distance, maximum peripheral edge, PCB material, PCB thickness and specific frequency of the metal patch; the reactance of the inductive unit can be adjusted by controlling the on-off of the plurality of tin-scratching welding discs; the specific reactance values of different structures can be confirmed by accurate modeling by means of simulation software, and the two sections only list specific two conditions; the size of the sensing units, the number of the tin points and the positions of the tin points can be selected according to requirements.

Referring to fig. 1 to 7, a microstrip filter provided in an embodiment of the present invention is disposed on a circuit board, where the circuit board includes a first conductive layer and a second conductive layer opposite to the first conductive layer, the microstrip filter includes a first microstrip device 10 exhibiting capacitive characteristics and a second microstrip device 100 exhibiting inductive characteristics, and the first microstrip device 10 and the second microstrip device 100 are connected in series or in parallel.

The first microstrip device 10 includes a plurality of metal plates disposed on the first conductive layer and the second conductive layer, the metal plates disposed on the first conductive layer and the metal plates disposed on the second conductive layer are in one-to-one correspondence and form capacitors with each other, and adjacent metal plates may be electrically connected by a connecting conductor 40; the second microstrip device 100 has a planar spiral structure or a serpentine routing structure, wherein when the second microstrip device 100 has a planar spiral structure, radially spaced adjacent microstrip line segments can be short-circuited by a short-circuit conductor 140; when the second microstrip device 100 has a serpentine routing structure, adjacent microstrip line segments at intervals can be shorted by the shorting conductor 140 in a direction in which one end extends toward the other end.

When the first microstrip device 10 and the second microstrip device 100 are connected in series, the first connection end 21 is electrically connected to one end of the first microstrip line 120, and the second connection end 22 is electrically connected to the other end of the first microstrip line 120; or, the first connection end 21 is electrically connected to the other end of the first microstrip line 120, and the second connection end 22 is electrically connected to one end of the first microstrip line 120. When the first microstrip device 10 and the second microstrip device 100 are connected in parallel, the first connection end 21 is electrically connected to one end or the other end of the first microstrip line 120; alternatively, the second connection terminal 22 is electrically connected to one end or the other end of the first microstrip line 120.

For further implementation of the first microstrip device 10 and the second microstrip device 100, please refer to the specific embodiments shown in fig. 1 to 5, which are not repeated herein.

Referring to fig. 6, when the first microstrip device 10 exhibiting a high-pass characteristic and the second microstrip device 100 exhibiting a low-pass characteristic are connected in series, the microstrip filter exhibits a band-pass filtering characteristic. Referring to fig. 7, when the first microstrip device 10 exhibiting the high-pass characteristic and the second microstrip device 100 exhibiting the low-pass characteristic are connected in parallel, the microstrip filter exhibits the band-stop filtering characteristic.

The microstrip filter is provided with a first microstrip device 10 and a second microstrip device 100, wherein the first microstrip device 10 is formed by coupling metal plates arranged on different layers of a circuit board, and the capacitance parameter of the first microstrip device 10 can be adjusted by connecting a conductor 40 and connecting the number of the metal plates in parallel; the second microstrip device 100 is formed by a planar helical structure arranged on the circuit board, and the inductance parameter of the second microstrip device 100 can be adjusted by shorting radially adjacent microstrip line segments through the shorting conductor 140, so that the working frequency of the microstrip filter can be dynamically adjusted.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.