Microstrip filter, electronic equipment and indoor distribution system

Abstract

A microstrip filter comprises a first substrate (11), a second substrate (12) and a dielectric layer (13), wherein the first substrate (11) and the second substrate (12) are oppositely arranged, and the dielectric layer (13) is located between the first substrate (11) and the second substrate (12). The first substrate (11) comprises a first substrate (110) and a patch array arranged on the side, close to the dielectric layer (13), of the first substrate (110). The second substrate (12) comprises a second substrate (120), a microstrip line (121) arranged on the side, close to the dielectric layer (13), of the second substrate (120), and a grounding layer (122) arranged on the side, away from the microstrip line (121), of the second substrate (120). The microstrip line (121) comprises a main transmission line (1211) and at least one branch knot (1212). The orthographic projection of the branch knot (1212) of the microstrip line (121) and the orthographic projection of the patch array on the first substrate (110) are overlapped, and the dielectric layer (13) is configured to adjust the resonant frequency between the patch array and the microstrip line (121) when the patch (111) of the patch array is applied with voltage.

Description

Microstrip filters, electronic equipment and indoor distribution systems

[0001] This article relates to but is not limited to the field of communication technology, and in particular to a microstrip filter, electronic equipment and indoor distribution system.

[0002] A filter is an electronic device or circuit that selectively passes or blocks signals within a specific frequency range. It is widely used in electronics, communications, and signal processing. The rapid development of modern communication technology has placed increasing demands on integration, low power consumption, and multi-functions. The realization of integrated and low-cost filter design is a development requirement.

[0003]

[0004] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0005] This embodiment provides a microstrip filter, an electronic device, and a room distribution system.

[0006] On the one hand, this embodiment provides a microstrip filter, comprising: a first substrate and a second substrate arranged opposite to each other, and a dielectric layer located between the first substrate and the second substrate. The first substrate comprises: a first substrate, and a patch array arranged on a side of the first substrate close to the dielectric layer. The second substrate comprises: a second substrate, a microstrip line arranged on a side of the second substrate close to the dielectric layer, and a ground layer arranged on a side of the second substrate away from the microstrip line; the microstrip line comprises: a main transmission line and at least one branch. The branch of the microstrip line overlaps with the patch array in the orthographic projection of the first substrate, and the dielectric layer is configured to adjust the resonant frequency between the patch array and the microstrip line when a voltage is applied to the patch of the patch array.

[0007] In some exemplary embodiments, the microstrip line includes a plurality of branches, and the plurality of branches are symmetrically arranged with respect to the main transmission line.

[0008] In some exemplary embodiments, the microstrip line includes eight branches, and the eight branches are symmetrically arranged with respect to the main transmission line.

[0009] In some exemplary embodiments, the microstrip line includes a plurality of stubs, and the plurality of stubs are connected to the same side of the main transmission line.

[0010] In some exemplary embodiments, the microstrip line includes four branches, and the four branches are connected to the same side of the main transmission line.

[0011] In some exemplary embodiments, an extension direction of the branch of the microstrip line is perpendicular to an extension direction of the main transmission line.

[0012] In some exemplary embodiments, the patch array includes multiple types of patches, and patches of the same type have the same shape and size; one type of patch corresponds to one tunable center frequency.

[0013] In some exemplary embodiments, the orthographic projection of at least one branch of the microstrip line on the first substrate overlaps with the orthographic projections of multiple patches of the patch array on the first substrate, and the multiple patches overlapping the same branch are of different types.

[0014] In some exemplary embodiments, a plurality of patches that overlap with the orthographic projection of the same branch on the first substrate are arranged in ascending order of size in a direction away from the main transmission line.

[0015] In some exemplary embodiments, at least one type of patch has a slotted region, and an orthographic projection of the slotted region on the first substrate overlaps an orthographic projection of a branch of the microstrip line on the first substrate.

[0016] In some exemplary embodiments, the orthographic projection of the grooved region on the first substrate is a rectangle.

[0017] In some exemplary embodiments, the orthographic projection of at least one type of patch on the first substrate is a rectangle.

[0018] In some exemplary embodiments, the first substrate further includes: a plurality of driving electrode lines disposed on the first substrate, and a plurality of patches of the same type are connected to the same driving electrode line.

[0019] In some exemplary embodiments, the first substrate further includes: a first alignment layer located on a side of the patch array close to the dielectric layer; the second substrate further includes: a second alignment layer located on a side of the microstrip line close to the dielectric layer.

[0020] In some exemplary embodiments, the medium layer includes a liquid crystal layer.

[0021] On the other hand, this embodiment provides a driving method for a microstrip filter as shown above, comprising: applying voltage to at least one patch in the patch array, changing the dielectric constant of the dielectric layer between the at least one patch and the branch, so as to control the resonant frequency between the at least one patch and the microstrip line.

[0022] On the other hand, this embodiment provides an electronic device, including the microstrip filter as described above.

[0023] On the other hand, this embodiment provides a room distribution system, including the microstrip filter as described above.

[0024] In some exemplary embodiments, the room-divided system includes: a room-divided signal source module, an intermediate module, and a room-divided antenna module; the intermediate module is connected between the room-divided signal source module and the room-divided antenna module. The room-divided antenna module includes a filter-mixing unit and a plurality of antennas, the filter-mixing unit is connected to the intermediate module and the plurality of antennas, and the filter-mixing unit includes at least one of the microstrip filters.

[0025] Other aspects will be apparent upon reading and understanding the drawings and detailed description.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide further understanding of the technical solution of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solution of the present disclosure and do not constitute a limitation on the technical solution of the present disclosure.

[0028] FIG1 is a schematic structural diagram of a microstrip filter according to at least one embodiment of the present disclosure;

[0029] FIG2 is a schematic diagram of a partial cross section along the Q-Q' direction in FIG1;

[0030] FIG3 is a schematic plan view of a first substrate according to at least one embodiment of the present disclosure;

[0031] FIG4 is a schematic plan view of a second substrate according to at least one embodiment of the present disclosure;

[0032] 5A and 5B are schematic diagrams of simulation results of a microstrip filter according to at least one embodiment of the present disclosure;

[0033] FIG6 is another schematic diagram of a microstrip filter according to at least one embodiment of the present disclosure;

[0034] FIG7 is another schematic diagram of a microstrip filter according to at least one embodiment of the present disclosure;

[0035] FIG8 is another schematic diagram of a microstrip filter according to at least one embodiment of the present disclosure;

[0036] FIG9 is a schematic diagram of the structure of a room-divided system according to at least one embodiment of the present disclosure;

[0037] FIG10 is a schematic diagram of a room-divided signal source module according to at least one embodiment of the present disclosure;

[0038] FIG11 is another schematic diagram of a room-divided signal source module according to at least one embodiment of the present disclosure;

[0039] FIG12 is a schematic diagram of a filtering and mixing unit of a room-based antenna module according to at least one embodiment of the present disclosure;

[0040] FIG13 is another schematic diagram of a filtering and mixing unit of a room-based antenna module according to at least one embodiment of the present disclosure;

[0041] FIG. 14 is a schematic diagram of an electronic device according to at least one embodiment of the present disclosure.

[0042] Details

[0043] The embodiments of the present disclosure will be described in detail below in conjunction with the accompanying drawings. The embodiments can be implemented in a plurality of different forms. A person skilled in the art can easily understand the fact that the method and content can be transformed into one or more forms without departing from the purpose and scope of the present disclosure. Therefore, the present disclosure should not be interpreted as being limited to the contents described in the following embodiments. In the absence of conflict, the embodiments in the present disclosure and the features in the embodiments can be arbitrarily combined with each other.

[0044] In the drawings, the size of one or more components, the thickness of a layer, or an area is sometimes exaggerated for the sake of clarity. Therefore, one embodiment of the present disclosure is not necessarily limited to the size, and the shapes and sizes of the components in the drawings do not reflect the true proportions. In addition, the drawings schematically show ideal examples, and one embodiment of the present disclosure is not limited to the shapes or values ​​shown in the drawings.

[0045] The ordinal numbers such as "first", "second", and "third" in the present disclosure are provided to avoid confusion of constituent elements, and are not intended to limit the quantity. The "plurality" in the present disclosure means a quantity of two or more than two.

[0046] In the present disclosure, for the sake of convenience, the words and phrases indicating the orientation or positional relationship, such as "middle", "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., are used to illustrate the positional relationship of the constituent elements with reference to the drawings. This is only for the convenience of describing the present specification and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation of the present disclosure. The positional relationship of the constituent elements is appropriately changed according to the direction in which the constituent elements are described. Therefore, it is not limited to the words and phrases described in the specification, and can be appropriately replaced according to the situation.

[0047] In the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate, or the internal communication of two elements. For ordinary technicians in this field, the meanings of the above terms in the present disclosure can be understood according to the circumstances.

[0048] In the present disclosure, "electrical connection" includes the case where components are connected together through an element having some electrical function. There is no particular limitation on the "element having some electrical function" as long as it can transmit electrical signals between connected components. Examples of "element having some electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other elements having one or more functions.

[0049] In the present disclosure, "parallel" means a state where the angle formed by two straight lines is greater than -10° and less than 10°, and therefore, a state where the angle is greater than -5° and less than 5° may be included. In addition, "perpendicular" means a state where the angle formed by two straight lines is greater than 80° and less than 100°, and therefore, a state where the angle is greater than 85° and less than 95° may be included.

[0050] In the present disclosure, "about" and "approximately" mean that the limits are not strictly defined and the numerical values ​​within the range of process and measurement errors are allowed. In the present disclosure, "same" can include completely consistent and approximately the same situations, and "approximately the same" means that the numerical values ​​differ by less than 10%.

[0051] This embodiment provides a microstrip filter, an electronic device, and a room distribution system, which can realize integrated and low-cost filter design.

[0052] The present embodiment provides a microstrip filter, comprising: a first substrate and a second substrate arranged opposite to each other, and a dielectric layer located between the first substrate and the second substrate. The first substrate comprises: a first substrate, and a patch array arranged on a side of the first substrate close to the dielectric layer. The second substrate comprises: a second substrate, a microstrip line arranged on a side of the second substrate close to the dielectric layer, and a grounding layer arranged on a side of the second substrate away from the microstrip line. The microstrip line comprises: a main transmission line and at least one branch. The branch of the microstrip line overlaps with the orthographic projection of the first substrate of the patch array. The dielectric layer is configured to adjust the resonant frequency between the patch array and the microstrip line when a voltage is applied to the patch of the patch array.

[0053] The microstrip filter provided in this embodiment controls the resonant frequency between the patch and the branch of the microstrip line where the orthographic projection overlaps by arranging the branch of the microstrip line to overlap with the orthographic projection of the patch array on the first substrate, and by applying voltage to the patch in the patch array to change the dielectric constant of the dielectric layer, thereby achieving a bandpass effect of allowing the corresponding frequency signal to pass through.

[0054] In some exemplary embodiments, the dielectric layer may include a liquid crystal layer. When the dielectric layer includes a liquid crystal layer, the frequency response between the patch and the microstrip line of the patch array can be controlled by utilizing the adjustable dielectric constant of the liquid crystal material at different voltages. In other examples, the dielectric layer may include at least one of the following: a lead zirconate titanate (PZT) film, a barium calcium zirconate titanate (BZT) film, a barium strontium titanate (BST) film, etc. This embodiment is not limited to this.

[0055] In some exemplary embodiments, the microstrip line may include a plurality of branches, and the plurality of branches may be symmetrically arranged about the main transmission line. For example, the microstrip line may include eight branches, and the eight branches may be symmetrically arranged about the main transmission line. In this example, by using symmetrically arranged branches, the radiation characteristics generated between the branches on both sides of the main transmission line and the patch array may be offset from each other, thereby avoiding leakage of electromagnetic wave radiation and avoiding interference with external devices.

[0056] In some exemplary embodiments, the microstrip line may include a plurality of branches, and the plurality of branches may be connected to the same side of the main transmission line. For example, the microstrip line may include four branches, and the four branches may be connected to the same side of the main transmission line. This example uses branches with an asymmetric layout, and the radiation of electromagnetic waves can be limited while ensuring that the distance between the patch array and the ground layer is close enough and the thickness of the first substrate and the second substrate is small (for example, much less than 1 / 10 of the wavelength).

[0057] In some exemplary embodiments, the patch array may include multiple types of patches, and patches of the same type may have the same shape and size. The number of patch types corresponds to the number of tunable center frequencies of the microstrip filter. In this example, patches of the same type may correspond to the same resonant center frequency. By setting multiple types of patches, this example can support the microstrip filter to achieve different frequency responses, and by applying voltage to one or more types of patches to control the resonant frequency between the patch and the microstrip line, so as to achieve the desired filter effect.

[0058] In some exemplary embodiments, the orthographic projection of at least one branch of the microstrip line on the first substrate may overlap with the orthographic projection of multiple patches of the patch array on the first substrate, and the multiple patches overlapping with the same branch belong to different types. In some examples, multiple patches overlapping with the orthographic projection of the same branch on the first substrate may be arranged in order of size from small to large in a direction away from the main transmission line. The arrangement of the patch array in this example can help ensure the effect of the microstrip filter.

[0059] In some exemplary embodiments, at least one type of patch may have a slotted area. The orthographic projection of the slotted area on the first substrate may overlap with the orthographic projection of the branch of the microstrip line on the first substrate. In some examples, the orthographic projection of the slotted area on the first substrate may be a rectangle. For example, the orthographic projection of at least one type of patch on the first substrate may be a rectangular ring. In this example, by providing a slotted area on the patch, the radiation side length of the patch overlapping the branch can be increased, which is conducive to reducing the size of the patch array.

[0060] In some exemplary embodiments, the first substrate may further include: a plurality of drive electrode lines disposed on the first substrate, and a plurality of patches of the same type are connected to the same drive electrode line. Since whether a voltage is applied to the patch affects the on-off of the corresponding frequency, this example uses the same drive voltage control for patches of the same type to make the frequency band of the response frequency narrower and achieve a better on-off effect. However, this embodiment is not limited to this. In other examples, a plurality of patches of the same type can be connected to different drive electrode lines, and by applying different voltages to patches of the same type, the isolation degree can be easily weakened.

[0061] The solution of this embodiment is described below by means of some examples.

[0062] FIG. 1 is a schematic diagram of the structure of a microstrip filter of at least one embodiment of the present disclosure. FIG. 2 is a schematic diagram of a partial cross-section along the Q-Q' direction in FIG. 1. In some examples, as shown in FIG. 1 and FIG. 2, the microstrip filter of this example may include: a first substrate 11 and a second substrate 12 arranged opposite to each other, and a dielectric layer 13 located between the first substrate 11 and the second substrate 12. In some examples, the dielectric layer 13 may be a liquid crystal layer, including a liquid crystal material. The first substrate 11 and the second substrate 12 may be arranged in a box to form a liquid crystal box, and the dielectric layer 13 may be arranged in the liquid crystal box. However, this embodiment is not limited to this. In other examples, the dielectric layer may include at least one of the following: a lead zirconate titanate (PZT) film, a barium calcium zirconate titanate (BZT) film, a barium strontium titanate (BST) film, and the like.

[0063] In some examples, as shown in FIG2 , a support structure 14 may be provided between the first substrate 11 and the second substrate 12. The support structure 14 may be a roughly annular structure surrounding the periphery of the first substrate 11 and the second substrate 12. The support structure 14 may include a sealant and a spacer (or spacer). By providing a support structure, a cavity may be formed between the first substrate 11 and the second substrate 12, and a liquid crystal layer may be formed between the first substrate 11 and the second substrate 12 by pouring liquid crystal material into the cavity. However, this embodiment is not limited to this. In this example, by providing a support structure, the gap between the first substrate and the second substrate may be maintained, which is beneficial to maintaining the uniformity of the liquid crystal layer and preventing the collapse of the cavity from affecting the thickness uniformity of the liquid crystal layer.

[0064] FIG3 is a schematic plan view of a first substrate of at least one embodiment of the present disclosure. In some examples, as shown in FIGS. 1 to 3, the first substrate 11 may include: a first substrate 110, and a patch array disposed on the first substrate 110. The patch array may be located on a side of the first substrate 110 close to the dielectric layer 13. The patch array may include: a plurality of patches 111 arranged in an array. Among them, a plurality of patches 111 arranged along a first direction X may be referred to as a row of patches, and a plurality of patches 111 arranged along a second direction Y may be referred to as a column of patches. The first direction X intersects with the second direction Y, for example, the first direction X may be perpendicular to the second direction Y.

[0065] In some examples, as shown in FIG3 , the first substrate 11 may further include: a plurality of driving electrode lines 113a and 113b located on the first substrate 110. The plurality of patches 111 of the patch array may be electrically connected to the plurality of driving electrode lines. For example, the plurality of patches 111 and the plurality of driving electrode lines 113a and 113b may be electrically connected in a one-to-one correspondence. For example, the patch 111 and the connected driving electrode lines may be an integrated structure connected to each other.

[0066] In some examples, as shown in FIG3, the first substrate 11 may further include: a plurality of drive transmission lines 114a and 114b located on the first substrate 110 and extending along the first direction X. The plurality of drive transmission lines 114a and 114b may be arranged in the edge regions on both sides of the patch array in the second direction Y. The plurality of drive transmission lines 114a and the plurality of drive electrode lines 113a may be electrically connected, and the plurality of drive transmission lines 114b and the plurality of drive electrode lines 113b may be electrically connected. For example, the plurality of drive electrode lines and the plurality of drive transmission lines may be electrically connected one by one. The drive transmission lines 114a and 114b may be configured to receive voltage signals transmitted by an external controller. The drive transmission lines and the connected drive electrode lines may be an integrated structure connected to each other. However, this embodiment is not limited to this. In other examples, the drive transmission lines may be omitted, and the drive electrode lines may extend directly outward and receive voltage signals transmitted by the controller.

[0067] In some examples, the patch array may include: multiple types of patches. Patches of the same type may have the same shape and size, and at least one of the sizes and shapes of patches of different types may be different. For example, patches of different types have the same shape and different sizes, or patches of different types have different shapes and sizes. A type of patch may correspond to a resonant center frequency. The number of patch types corresponds to the number of resonant center frequencies. Different types of patches correspond to different resonant center frequencies. This example is illustrated by taking three types of patches (e.g., the first type patch 111a, the second type patch 111b, and the third type patch 111c shown in FIG. 3) as an example. The microstrip filter of this example may correspond to three resonant center frequencies.

[0068] In some examples, each type of patch may have a slotted area. For example, the first type of patch 111a may have a first slotted area 1110a, the second type of patch 111b may have a second slotted area 1110b, and the third type of patch 111c may have a third slotted area 1110c. The orthographic projections of the first slotted area 1110a, the second slotted area 1110b, and the third slotted area 1110c on the first substrate 110 may all be approximately rectangular. The sizes of the first slotted area 1110a, the second slotted area 1110b, and the third slotted area 1110c may increase in sequence.

[0069] In some examples, as shown in FIG3 , the shapes of the orthographic projections of the first type patch 111a, the second type patch 111b, and the third type patch 111c on the first substrate 1110 may all be rectangular rings, the size of the first type patch 111a may be smaller than the size of the second type patch 111b, and the size of the second type patch 111b may be smaller than the size of the third type patch 111c.

[0070] FIG4 is a schematic plan view of the second substrate of at least one embodiment of the present disclosure. In some examples, as shown in FIGS. 1 to 4, the second substrate 12 may include: a second substrate 120, a microstrip line 121 and a ground layer 122 disposed on opposite sides of the second substrate 120. The microstrip line 121 may be located on a side of the second substrate 120 close to the dielectric layer 13, and the ground layer 122 may be located on a side of the second substrate 120 away from the dielectric layer 13. The ground layer 122 may be a whole metal layer, and the orthographic projection of the ground layer 122 on the second substrate 120 may cover the orthographic projection of the microstrip line 121 on the second substrate 120. This example uses the microstrip line 121, the second substrate 120 and the ground layer 122 to form a microstrip transmission structure.

[0071] In some examples, as shown in FIG4 , the microstrip line 121 may include: a main transmission line 1211 and at least one branch 1212. The shape of the orthographic projection of the main transmission line 1211 on the second substrate 120 may be a strip structure extending along the first direction X. One end of the main transmission line 1211 may be connected to the first port 15a, and the other end of the main transmission line 1211 may be connected to the second port 15b. The first port 15a and the second port 15b may be the input port and the output port of the microstrip filter. This embodiment does not limit the type and arrangement of the first port and the second port.

[0072] In some examples, the microstrip line 121 may include a plurality of branches 1212, for example, eight branches 1212. The plurality of branches 1212 and the main transmission line 1211 may be an integral structure connected to each other. The shape of the orthographic projection of a single branch 1212 on the second substrate 120 may be roughly a strip structure extending along the second direction Y. The extension direction of the branch 1212 may be perpendicular to the extension direction of the main transmission line 1211. The eight branches 1212 in this example may be symmetrically arranged about the main transmission line 1211. The sizes of the eight branches 1212 may be roughly the same. The spacing between adjacent branches 1212 may be roughly the same. The microstrip line 121 may be roughly symmetrical about the midline of the first direction X, and may also be roughly symmetrical about the midline of the second direction Y. In this example, the branches of the microstrip line may be arranged symmetrically. Due to the bilaterally symmetrical design, the surface current directions of the patch array may be opposite, so that the generated radiation characteristics cancel each other out, thereby avoiding interference with external devices.

[0073] In some examples, the orthographic projection of each branch 1212 of the microstrip line 121 on the first substrate 110 may overlap with the orthographic projection of the patch array on the first substrate 110, and the orthographic projection of the main transmission line 1211 and the patch array on the first substrate 110 may not overlap. The patch array can be arranged roughly symmetrically about the main transmission line 1211. The patch array of this example can be arranged in six rows and four columns. The main transmission line 1211 can be arranged in three rows and four columns on one side of the second direction Y, and three rows and four columns on the side in the opposite direction of the second direction Y. The sizes of multiple patches in the same row of patches are the same, and the multiple patches in a row of patches belong to the same type; the sizes of multiple patches in the same column of patches can be different, and the multiple patches in a column of patches belong to different types.

[0074] In some examples, the orthographic projection of each branch 1212 on the first substrate 110 overlaps with the orthographic projection of a column of patches (including three different types of patches, namely, the first type of patch 111a, the second type of patch 111b and the third type of patch 111c) on the first substrate 110. The three patches that overlap with the orthographic projection of each branch 1212 on the first substrate 110 can be arranged in order from small to large in size in a direction away from the main transmission line 1211. The first type of patch 111a, the second type of patch 111b and the third type of patch 111c located in the same column can be aligned in the second direction Y, and the midlines of the three patches along the first direction X can overlap. The midlines of the three patches along the first direction X can roughly overlap with the midlines of the overlapping branches 1212 along the first direction X. However, this embodiment is not limited to this. In other examples, a row of patches that overlap with the orthographic projection of the branch on the first substrate can be arranged in order of size from large to small in a direction away from the main transmission line. In other examples, multiple patches of the patch array can be arranged in a nested manner, for example, a first type of patch can be arranged in the second slotted area of ​​a second type of patch, or a second type of patch can be arranged in the third slotted area of ​​a third type of patch.

[0075] In some examples, as shown in FIG2 , the first substrate 11 may further include: a first alignment layer 112, located on a side of the patch array close to the dielectric layer 13. The second substrate 12 may further include: a second alignment layer 123, located on a side of the microstrip line 121 close to the dielectric layer 13. In this example, by providing the first alignment layer and the second alignment layer, the liquid crystal molecules in the dielectric layer may be aligned so that the liquid crystal molecules are arranged in a certain direction.

[0076] In some examples, the microstrip filter of this example uses a double-sided metal process on the second substrate to form a microstrip transmission structure. The liquid crystal molecules of the liquid crystal layer are anisotropic materials, and have different dielectric constants along the long axis and short axis directions. After the deflection voltage is applied to both ends of the liquid crystal molecules, the liquid crystal molecules will deflect, and the dielectric constant of the liquid crystal material will change with the deflection of the liquid crystal. By applying a voltage to the patch of the patch array, the liquid crystal deflection can be used to adjust the resonant frequency between the patch and the overlapping microstrip transmission structure. The dielectric constant of the liquid crystal molecules of the liquid crystal layer corresponding to each patch and the microstrip transmission structure can be independently controlled and changed. When a voltage is applied to the corresponding patch by driving the electrode line, the liquid crystal deflection can be used to achieve the resonance of the patch and the overlapping microstrip transmission structure at the non-center frequency, so that the center frequency signal corresponding to the patch can pass through, forming a bandpass effect; when the voltage is not applied to the patch by driving the electrode line, the patch and the overlapping microstrip transmission structure resonate at the center frequency, so that the center frequency signal corresponding to the patch is turned off, forming a band-stop effect. The liquid crystal layer of this example is configured to control the on and off of the resonant center frequency corresponding to the patch. In some examples, the number of types of patches can determine the number of tunable center frequencies of the microstrip filter. One type of patch corresponds to a tunable center frequency, and different types of patches can correspond to different center frequencies. In some examples, the number of branches of the microstrip line can determine the bandwidth corresponding to the tunable center frequency. The more branches the microstrip line has, the more patches of the same type overlap with the branches, which is conducive to increasing the bandwidth corresponding to the center frequency corresponding to the patch of this type and improving the filtering effect. The fewer branches the microstrip line has, the fewer patches of the same type overlap with the branches, so that the bandwidth corresponding to the center frequency corresponding to the patch of this type is reduced.

[0077] In some examples, the driving voltage applied to the patch of the patch array may depend on the material and thickness of the dielectric layer. The driving voltage may be less than 30 V. For example, the dielectric layer may be a liquid crystal layer, and the driving voltage may be less than or equal to 8 V.

[0078] Figures 5A and 5B are schematic diagrams of simulation results of a microstrip filter according to at least one embodiment of the present disclosure. Figure 5A shows the simulation result after voltage is applied to the first type of patch of the patch array of the microstrip filter shown in Figure 1. Figure 5B shows the simulation result after no voltage is applied to the first type of patch of the patch array of the microstrip filter shown in Figure 1.

[0079] In some examples, the length of the first type of patch can be 10.5 millimeters (mm) and the width can be 5 mm; the length and width of the first slotted area of ​​the first type of patch can be 6.4 mm and 0.8 mm, respectively. The first type of patch can correspond to 2.5 GHz to 2.6 GHz. The length of the second type of patch can be 23 mm and the width can be 8 mm; the length and width of the second slotted area of ​​the second type of patch can be 10 mm and 0.8 mm, respectively. The second type of patch can correspond to 0.74 GHz to 0.76 GHz. The length of the third type of patch can be 23 mm and the width can be 10 mm, the length and width of the third slotted area of ​​the third type of patch can be 20 mm and 0.8 mm, respectively, and the third type of patch can correspond to 1.34 GHz to 1.38 GHz. The width of the main transmission line of the microstrip line (i.e., the length along the second direction Y) can be about 1.6 mm, the width of the branch (i.e., the length along the first direction X) can be about 4 mm, the length of the branch (i.e., the length along the second direction Y) can be about 72 mm, and the spacing between adjacent branches can be about 28 mm. The thickness of the liquid crystal layer may be about 20 micrometers (um).

[0080] In some examples, FIG. 5A and FIG. 5B compare and illustrate whether 2.5 GHz to 2.6 GHz can pass. FIG. 5A shows a situation where a voltage is applied to the first type of patch, and no voltage is applied to the second type of patch and the third type of patch, and FIG. 5B shows a situation where no voltage is applied to the first type of patch, the second type of patch and the third type of patch. It can be seen from FIG. 5A that when a voltage is applied to the first type of patch, a signal from 2.5 GHz to 2.6 GHz can pass through, forming a bandpass effect. It can be seen from FIG. 5B that when the voltage applied to the first type of patch is removed, the loss at 2.5 GHz to 2.6 GHz reaches 30 dB, which is equivalent to that this part of the signal does not pass, forming a band-stop effect. This example can achieve the purpose of signal on and off by controlling the voltage applied to the corresponding type of patch. In some examples, the number of types of patches can be reasonably designed according to the number of frequencies to be reused.

[0081] The following is an exemplary description of the preparation process of a microstrip filter. The "patterning process" mentioned in the present disclosure includes processes such as coating photoresist, mask exposure, development, etching, and stripping photoresist for metal materials, inorganic materials, or transparent conductive materials, and includes processes such as coating organic materials, mask exposure, and development for organic materials. Deposition can be any one or more of sputtering, evaporation, and chemical vapor deposition, coating can be any one or more of spraying, spin coating, and inkjet printing, and etching can be any one or more of dry etching and wet etching, which are not limited in the present disclosure. "Thin film" refers to a layer of thin film made of a certain material on a substrate by deposition, coating, or other processes. If the "thin film" does not require a patterning process during the entire production process, the "thin film" can also be called a "layer". If the "thin film" requires a patterning process during the entire production process, it is called a "thin film" before the patterning process and a "layer" after the patterning process. The "layer" after the patterning process contains at least one "pattern".

[0082] The "A and B are arranged in the same layer" mentioned in the present disclosure means that A and B are formed simultaneously by the same patterning process. In the exemplary embodiments of the present disclosure, "the orthographic projection of A includes the orthographic projection of B" means that the boundary of the orthographic projection of B falls within the boundary range of the orthographic projection of A, or the boundary of the orthographic projection of A overlaps with the boundary of the orthographic projection of B.

[0083] In some exemplary embodiments, a process of preparing a microstrip filter may include the following operations.

[0084] (1) Prepare a first substrate. In some examples, a routing layer and a first conductive layer are sequentially formed on the first substrate. For example, a routing film is coated on the first substrate, and a routing layer is formed by a patterning process; then, a first conductive film is coated to form a first conductive layer. The first conductive layer may be made of a metal material with good conductivity, such as copper (Cu). The first conductive layer may include a patch array. The routing layer may be made of a metal material or a transparent conductive material, such as indium tin oxide (ITO). The routing layer may include a plurality of drive electrode lines, or a plurality of drive electrode lines and a plurality of drive transmission lines.

[0085] In some examples, a first alignment film may be coated on the first substrate on which the aforementioned pattern is formed, the first alignment film is cured, and the cured first alignment film is aligned using an alignment technique to obtain a transparent first alignment layer. The first alignment layer may cover the first conductive layer and the wiring layer.

[0086] (2) Prepare a second substrate. In some examples, a second conductive layer and a ground layer are formed on opposite sides of the second substrate. The second conductive layer may be made of a metal material with good conductivity, such as copper (Cu). The second conductive layer may include a microstrip line. A ground layer may be formed on a side of the second substrate away from the second conductive layer by coating. The orthographic projection of the ground layer on the second substrate may include the orthographic projection of the second conductive layer on the second substrate.

[0087] In some examples, a second alignment film may be coated on the second substrate on which the aforementioned pattern is formed, the second alignment film is cured, and the cured second alignment film is aligned using an alignment technique to obtain a transparent second alignment layer. The second alignment layer may cover the second conductive layer.

[0088] In some examples, the alignment technology may include: a friction alignment technology and an ultraviolet light alignment technology, and the alignment technology may form grooves on the surface of the first alignment layer to align the liquid crystal molecules so that the liquid crystal molecules are arranged in a certain direction. The material of the first alignment film may be polyimide, polyamide, polyethylene, polystyrene or polyvinyl alcohol. However, this embodiment is not limited to this.

[0089] In some examples, the first substrate and the second substrate may be rigid substrates, such as glass substrates. By forming a liquid crystal cell using a rigid substrate, the thickness of the liquid crystal cell can be accurately controlled to ensure the uniformity of the thickness of the liquid crystal cell. Moreover, microstrip filters based on glass substrates are easy to prepare in large quantities, which is conducive to reducing device complexity and cost.

[0090] (3) Align the first substrate and the second substrate to prepare a liquid crystal box.

[0091] In some examples, a sealant is applied around the first substrate or the second substrate, the first substrate and the second substrate are aligned, and a support structure is formed between the first substrate and the second substrate by curing the sealant. A cavity is formed by the first substrate, the second substrate and the support structure. A plurality of crystal injection ports can be arranged in sequence on the support structure, and liquid crystal material is injected through the crystal injection ports to form a liquid crystal layer as a dielectric layer.

[0092] In this example, the branches and patches of the microstrip line can form the upper and lower electrodes for controlling the operation of the liquid crystal layer. By utilizing the electrically adjustable dielectric properties of the liquid crystal material itself, the resonant frequency of the filter can be easily adjusted. When adjusting the resonant frequency of the filter, a driving voltage can be applied through the patch, so that a voltage difference is generated between the patch and the branches, thereby changing the arrangement of the liquid crystal molecules and achieving the effect of adjusting the resonant frequency.

[0093] The microstrip filter provided in this example can design multiple adjustable units (i.e., patches and branch structures sandwiching liquid crystal layers) with adjustable resonant frequencies on a glass substrate through semiconductor thin film technology, and control the resonant frequency of the adjustable unit by applying voltage to achieve different frequency responses of the same adjustable unit, and then achieve a filter effect by combining and controlling multiple adjustable units. Since the adjustable units in this example can control different frequency responses by applying voltage, different filtering effects can be controlled by applying different voltage combinations, thereby achieving the purpose of simplifying the design and reducing costs.

[0094] FIG6 is another schematic diagram of a microstrip filter of at least one embodiment of the present disclosure. In some examples, as shown in FIG6 , the patch array can be symmetrically arranged about the main transmission line of the microstrip line 121, and in the patch array located on one side of the main transmission line, the same type of patches can be electrically connected to the same drive electrode line 113a or 113b. For example, a row of the same type of patches can be electrically connected to the same drive electrode line 113a or 113b. The rest of the description of the microstrip filter of this example can refer to the description of the aforementioned embodiment, so it will not be repeated here.

[0095] In this example, since the presence or absence of applied voltage affects the on-off of the corresponding frequency, applying a uniform voltage to the same type of patch can narrow the frequency band of the response frequency and obtain a better on-off effect. However, this embodiment is not limited to this. In other examples, different voltages can be applied to the same type of patch to widen the frequency band of the response frequency and weaken the on-off isolation.

[0096] FIG7 is another schematic diagram of a microstrip filter of at least one embodiment of the present disclosure. In some examples, as shown in FIG7 , the orthographic projection of the patch 111 of the patch array on the first substrate may be a rectangle. The patch array of this example may include three types of patches, and the orthographic projections of the three types of patches on the substrate may all be rectangular and of different sizes. Patches of the same type may be electrically connected to the same drive electrode line 113a or 113b. For example, a row of patches of the same type may be electrically connected to the same drive electrode line 113a or 113b. The remaining description of the microstrip filter of this example may refer to the description of the aforementioned embodiment, so it will not be repeated here.

[0097] In this example, when the area of ​​the microstrip filter is not limited, a solid patch can be used to achieve a filtering effect.

[0098] FIG8 is another schematic diagram of a microstrip filter according to at least one embodiment of the present disclosure. In some examples, as shown in FIG8 , the microstrip line 121 may include four branches, and the four branches are connected to the same side of the main transmission line. The patch array may include three rows and four columns. The remaining description of the microstrip filter of this example can refer to the description of the aforementioned embodiment, so it will not be repeated here.

[0099] In this example, the branches of the microstrip line can adopt an asymmetric structure with respect to the main transmission line, which can limit the radiation of electromagnetic waves while ensuring that the distance between the patch array and the ground layer is close enough and the thickness of the first substrate and the second substrate is small (for example, much less than 1 / 10 wavelength).

[0100] This embodiment also provides a driving method for a microstrip filter, which is applied to the microstrip filter as described above. The driving method of this example may include: applying a voltage to at least one patch in the patch array to change the dielectric constant of the dielectric layer between the patch and the branch to control the resonant frequency between at least one patch and the microstrip line.

[0101] In some examples, the patch array includes multiple types of patches. By applying voltage to multiple patches of the same type, the signal corresponding to the resonant center frequency corresponding to the patch of that type can pass through, forming a bandpass effect. By controlling the combination of whether to apply voltage to multiple types of patches, the desired filtering effect can be achieved. The control unit (for example, a control program) can provide a voltage signal to the corresponding patch by driving the electrode line, and control the resonant frequency by controlling the voltage applied to the corresponding patch to achieve the desired filtering effect.

[0102] The driving method of the microstrip filter of this embodiment can refer to the description of the aforementioned embodiment, so it will not be described again here.

[0103] This embodiment also provides a room distribution system, including the microstrip filter as described above.

[0104] In some examples, with the development and maturity of 5G technology, indoor users have increasingly urgent requirements for high transmission with large bandwidth. Millimeter-wave-based digital indoor division is limited by technology, cost and other reasons and has not yet been commercialized; the relatively mature traditional antenna distribution system (DAS, Distributed Antenna System) cannot carry higher data volume services. The reuse and capacity expansion improvement of traditional DAS has become a better solution. The two mainstream technical routes are active frequency conversion DAS system and passive frequency conversion DAS system. Both technical routes divide and convert a 5G signal, convert it back after transmission, and distinguish it from the original frequency through different polarization forms to achieve the effect of multiple input multiple output (MIMO) and achieve capacity expansion. However, any frequency conversion solution involves frequency conversion, matching, and filtering devices, usually using discrete devices, low temperature co-fired ceramics (LTCC, Low Temperature Co-fired Ceramic), dielectric filters, etc., which will bring a series of problems such as customized design, high cost, and large volume.

[0105] The indoor distributed system of this embodiment can adopt the microstrip filter provided in the aforementioned embodiment. The resonant frequency can be controlled by applying voltage, and the filter effect can be achieved by combined control of the patches that require applied voltage. Since the control of the patches that require applied voltage can be controlled by program, different filtering functions can be achieved. The indoor distributed system of this embodiment can simplify the complexity of system design and reduce system modification costs by utilizing the aforementioned microstrip filter.

[0106] The following is an example of the room distribution system in this example.

[0107] FIG9 is a schematic diagram of the structure of a room-divided system of at least one embodiment of the present disclosure. In some examples, as shown in FIG9 , the room-divided system of this example may include: a room-divided signal source module 31, an intermediate module 32, and a room-divided antenna module 33. The room-divided signal source module 31 may be configured to provide a wireless signal as an input to the system. For example, the wireless signal provided by the room-divided signal source module 31 may include: a radio frequency signal RF1 (e.g., 900 MHz), a radio frequency signal RF2 (e.g., 1800 MHz / 2 GHz / 2.3 GHz / 2.6 GHz), a local oscillator signal LO (e.g., 1100 MHz), and an intermediate frequency signal IF (e.g., 1500 MHz). Multiple wireless signals may be combined by a combiner and then connected to the intermediate module 32 through a cable.

[0108] In some examples, after receiving the wireless signal provided by the indoor signal source module 31 through the cable, the intermediate module 32 achieves coverage and capacity enhancement of the indoor area by amplifying, distributing and managing the wireless signal. For example, the intermediate module 32 may include: a power divider, a feeder and a coupler.

[0109] In some examples, the output signal of the intermediate module 32 can be provided to the indoor antenna module 33. The indoor antenna module 33 can provide high-quality wireless signal coverage and transmission in an indoor environment. The indoor antenna module 33 may include: a filter mixing unit, and multiple antennas. The filter mixing unit can be connected to the intermediate module 32 and the multiple antennas. The filter mixing unit can filter and mix the output signal of the intermediate module 32 to obtain a multi-channel wireless signal, which is radiated through multiple antennas.

[0110] FIG10 is a schematic diagram of a room-divided signal source module of at least one embodiment of the present disclosure. In some examples, as shown in FIG10, for the radio frequency signal RF1 and the radio frequency signal RF2 in the multi-channel wireless signal, after receiving the wireless signal, digital-to-analog conversion (DA, Digital to Analog), mixing, filtering and amplification processing can be performed in sequence, and then combined through a combiner. The original 2.6GHz signal in the signal source part is divided into two channels, one of which is transmitted using a 2.6GHz carrier and combined through digital-to-analog conversion, mixing, filtering and amplification processing; the other channel is converted into an intermediate frequency signal by mixing with the local oscillator signal after digital-to-analog conversion, mixing and filtering, and the intermediate frequency signal is combined with other wireless signals after filtering and amplification. The local oscillator signal is combined with other signals after amplification. The processing units for local oscillation, mixing, filtering and amplification of the room-divided signal source module of this example can all be integrated inside the signal source device, and after being combined by the combiner, they are connected to the intermediate module through a cable.

[0111] FIG11 is another schematic diagram of the room-divided signal source module of at least one embodiment of the present disclosure. In some examples, as shown in FIG11, the radio frequency signal RF1 and the radio frequency signal RF2 can be sequentially subjected to digital-to-analog conversion, mixing, filtering and amplification processing, and then combined and transmitted through the first combiner. The original 2.6GHz signal in the signal source part can be divided into two paths, the first path uses a 2.6GHz carrier for transmission, and is combined with other radio frequency signals after digital-to-analog conversion, mixing, filtering and amplification processing; the second path signal is converted into an intermediate frequency signal by mixing with the local oscillator signal after digital-to-analog conversion, mixing and filtering, and the intermediate frequency signal is combined with other wireless signals through the second combiner after filtering and amplification. Among them, the processing units such as mixing, filtering and amplification of the second 2.6GHz signal can be packaged separately (such as the external unit indicated by the dotted box in FIG11), and connected to the signal source device integrated with the remaining radio frequency signals. In some examples, the filter in the external unit can adopt the microstrip filter provided in the aforementioned embodiment, which can simplify the design and reduce costs.

[0112] The indoor distributed system in this example divides the 2.6GHz signal of the source part into two paths. One path still uses 2.6GHz carrier transmission, and the other path is converted into an intermediate frequency signal transmission through a mixer. This eliminates the need to change the intermediate system, ensuring extremely low modification costs.

[0113] FIG12 is a schematic diagram of a filtering and mixing unit of a room-based antenna module according to at least one embodiment of the present disclosure. In some examples, as shown in FIG12, the input port of the room-based antenna module can receive an output signal from an intermediate module. After the room-based antenna module receives the signal, a local oscillator LO signal, an intermediate frequency signal IF, a radio frequency signal RF1, and a radio frequency signal RF2 can be obtained by using multiple filters (for example, filters F1, F2, F3, and F4). In the filtering and mixing unit, the intermediate frequency signal IF can be re-converted to 2.6 GHz. Among them, the intermediate frequency signal IF is mixed with the output of the local oscillator signal LO after matching the output of the balun B1, and the output of the mixer is processed by matching the balun B3 and the filter F5 to obtain a 2.6 GHz signal. The antenna can use different polarization radiation for the 2.6 GHz signal in the radio frequency signal RF2 and the 2.6 GHz signal obtained by frequency conversion, thereby achieving the purpose of MIMO multi-stream.

[0114] In some examples, at least one of the filters F1, F2, F3, F4 and F5 in the filtering and mixing unit shown in Figure 12 can adopt a microstrip filter as described in the above-mentioned embodiment, and the patch to which the voltage needs to be applied in the microstrip filter can be controlled through program coding, and voltage can be applied to the corresponding patch to achieve different filtering effects.

[0115] In this example, all or part of the filters in the filtering and mixing units in the indoor distributed system adopt microstrip filters as in the above-mentioned embodiment. The filtering effect of the corresponding microstrip filters only needs to be controlled through different codes, which can reduce the types of filters required and the types of devices, thereby helping to reduce the design complexity and modification costs of the system.

[0116] FIG13 is another schematic diagram of the filtering and mixing unit of the room-based antenna module of at least one embodiment of the present disclosure. In some examples, as shown in FIG13, since additional devices such as filters and mixers are added to the room-based antenna module to convert the intermediate frequency signal, additional attenuation of the intermediate frequency signal will result, resulting in an imbalance of the multi-input and multi-output signal. Therefore, an amplifier is added to amplify the frequency-converted signal after mixing the local oscillator signal LO and the intermediate frequency signal IF to ensure that the levels of the two 2.6 GHz (original 2.6 GHz and 2.6 GHz obtained by frequency conversion) signals are equivalent. However, this embodiment is not limited to this. In other examples, an attenuator can be added to attenuate the original 2.6 GHz signal to ensure that the levels of the two 2.6 GHz (original 2.6 GHz and 2.6 GHz obtained by frequency conversion) signals are equivalent.

[0117] In some examples, at least one of the filters F1, F2, F3, F4 and F5 in the filtering and mixing unit shown in Figure 13 can adopt a microstrip filter as described in the above-mentioned embodiments, and the patches in the microstrip filter to which voltage needs to be applied can be controlled through program coding, and voltage can be applied to the corresponding patches to achieve different filtering effects.

[0118] The indoor distributed system of this example can reduce the types of devices required for the entire system by adopting the microstrip filter as described above, which is beneficial to reducing the cost of system modification, and can also simplify the design and reduce the design complexity of the system.

[0119] FIG14 is a schematic diagram of an electronic device of at least one embodiment of the present disclosure. As shown in FIG14, the present embodiment provides an electronic device 91, comprising: a microstrip filter 910 as described in the above embodiment and a control unit. The control unit can control the voltage application mode of the patch array of the microstrip filter 910 (i.e., which patches are applied with voltage and which patches are not applied with voltage), thereby controlling the resonant frequency between the corresponding patches and branches to achieve the corresponding filtering effect.

[0120] In some examples, the electronic device 91 may be any product or component with communication function, such as a mobile phone, a navigation device, a game console, a television (TV), a car stereo, a tablet computer, a personal multimedia player (PMP), a personal digital assistant (PDA), etc. However, this embodiment is not limited to this.

[0121] The drawings in the present disclosure only relate to the structures involved in the present disclosure, and other structures can refer to the usual design. In the absence of conflict, the embodiments of the present disclosure, i.e., the features in the embodiments, can be combined with each other to obtain new embodiments. It should be noted that the above-mentioned embodiments or implementation methods are merely exemplary and not restrictive. Therefore, the present disclosure is not limited to the contents shown and described in detail herein. Various modifications, replacements or omissions can be made to the forms and details of implementation without departing from the scope of the present disclosure.

Claims

A microstrip filter, comprising: A first substrate and a second substrate arranged opposite to each other, and a dielectric layer located between the first substrate and the second substrate; The first substrate comprises: a first substrate, and a patch array arranged on a side of the first substrate close to the dielectric layer; the second substrate comprises: a second substrate, a microstrip line arranged on a side of the second substrate close to the dielectric layer, and a ground layer arranged on a side of the second substrate away from the microstrip line; the microstrip line comprises: a main transmission line and at least one branch; the branch of the microstrip line overlaps with the patch array in the orthographic projection of the first substrate, and the dielectric layer is configured to adjust the resonant frequency between the patch array and the microstrip line when a voltage is applied to the patch of the patch array. The microstrip filter according to claim 1, wherein: The microstrip line includes a plurality of branches, and the plurality of branches are symmetrically arranged with respect to the main transmission line. The microstrip filter according to claim 2, wherein: The microstrip line includes eight branches, and the eight branches are symmetrically arranged with respect to the main transmission line. The microstrip filter according to claim 1, wherein: The microstrip line includes a plurality of branches, and the plurality of branches are connected to the same side of the main transmission line. The microstrip filter according to claim 4, wherein: The microstrip line includes four branches, and the four branches are connected to the same side of the main transmission line. The microstrip filter according to claim 1, wherein: An extension direction of the branch of the microstrip line is perpendicular to an extension direction of the main transmission line. The microstrip filter according to any one of claims 1 to 6, wherein: The patch array includes multiple types of patches, and patches of the same type have the same shape and size; one type of patch corresponds to one tunable center frequency. The microstrip filter according to claim 7, wherein: The orthographic projection of at least one branch of the microstrip line on the first substrate overlaps with the orthographic projections of multiple patches of the patch array on the first substrate, and the multiple patches overlapping the same branch belong to different types. The microstrip filter according to claim 8, wherein: A plurality of patches that overlap with the orthographic projection of the same branch on the first substrate are arranged in order of size from small to large in a direction away from the main transmission line. The microstrip filter according to claim 7, wherein: At least one type of patch has a slotted region, and an orthographic projection of the slotted region on the first substrate overlaps with an orthographic projection of a branch of the microstrip line on the first substrate. The microstrip filter according to claim 10, wherein: The orthographic projection of the grooved area on the first substrate is a rectangle. The microstrip filter according to claim 7, wherein: The orthographic projection of at least one type of patch on the first substrate is a rectangle. The microstrip filter according to claim 7, wherein: The first substrate further includes: a plurality of driving electrode lines arranged on the first substrate, and a plurality of patches of the same type are connected to the same driving electrode line. The microstrip filter according to claim 1, wherein: The first substrate further includes: a first alignment layer located on a side of the patch array close to the dielectric layer; the second substrate further includes: a second alignment layer located on a side of the microstrip line close to the dielectric layer. The microstrip filter according to claim 1, wherein: The medium layer includes a liquid crystal layer. A method for driving a microstrip filter according to any one of claims 1 to 15, comprising: A voltage is applied to at least one patch in the patch array to change the dielectric constant of the dielectric layer between the at least one patch and the branch, so as to control the resonant frequency between the at least one patch and the microstrip line. An electronic device comprises the microstrip filter according to any one of claims 1 to 15. A room distribution system, comprising the microstrip filter as claimed in any one of claims 1 to 15. The room distribution system according to claim 18, comprising: A room-divided signal source module, an intermediate module and a room-divided antenna module; the intermediate module is connected between the room-divided signal source module and the room-divided antenna module; the room-divided antenna module includes a filter mixing unit and multiple antennas, the filter mixing unit is connected to the intermediate module and the multiple antennas, and the filter mixing unit includes at least one of the microstrip filters.

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