Microstrip filter, electronic device and room division system

Abstract

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

Description

Technical Field

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

[0002] A filter is an electronic device or circuit used to selectively allow or block signals within a specific frequency range. It is widely used in electronics, communications, and signal processing. The rapid development of modern communication technologies places increasingly higher demands on integration, low power consumption, and multifunctionality, making integrated and low-cost filter design a necessary development requirement. Summary of the Invention

[0003] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0004] This embodiment provides a microstrip filter, electronic device, and indoor distribution system.

[0005] On one hand, this embodiment provides a microstrip filter, including: a first substrate and a second substrate disposed opposite to each other, and a dielectric layer located between the first substrate and the second substrate. The first substrate includes: a first substrate and a patch array disposed on the side of the first substrate near the dielectric layer. The second substrate includes: a second substrate, a microstrip line disposed on the side of the second substrate near the dielectric layer, and a ground layer disposed on the side of the second substrate away from the microstrip line; the microstrip line includes: a main transmission line and at least one stub. The stub of the microstrip line overlaps with the orthographic projection of the patch array onto 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 patches of the patch array.

[0006] In some exemplary embodiments, the microstrip line includes multiple stubs that are symmetrically arranged about the main transmission line.

[0007] In some exemplary embodiments, the microstrip line includes eight stubs that are symmetrically arranged about the main transmission line.

[0008] In some exemplary embodiments, the microstrip line includes multiple stubs connected to the same side of the main transmission line.

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

[0010] In some exemplary embodiments, the extension direction of the microstrip line stubs is perpendicular to the extension direction of the main transmission line.

[0011] In some exemplary embodiments, the patch array includes multiple types of patches, with patches of the same type having the same shape and size; one type of patch corresponds to one tunable center frequency.

[0012] In some exemplary embodiments, the orthographic projection of at least one branch of the microstrip line onto the first substrate overlaps with the orthographic projection of multiple patches of the patch array onto the first substrate, and the multiple patches that overlap with the same branch belong to different types.

[0013] In some exemplary embodiments, multiple patches that overlap with the orthographic projection of the same branch onto the first substrate are arranged in ascending order of size toward the direction away from the main transmission line.

[0014] In some exemplary embodiments, at least one type of patch has a slotted region in which the orthographic projection of the slotted region onto the first substrate overlaps with the orthographic projection of the stub of the microstrip line onto the first substrate.

[0015] In some exemplary embodiments, the orthographic projection of the slotted area onto the first substrate is rectangular.

[0016] In some exemplary embodiments, at least one type of patch has a rectangular orthographic projection onto the first substrate.

[0017] 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 connected to the same driving electrode line.

[0018] In some exemplary embodiments, the first substrate further includes: a first alignment layer located on the side of the patch array near the dielectric layer; the second substrate further includes: a second alignment layer located on the side of the microstrip line near the dielectric layer.

[0019] In some exemplary embodiments, the dielectric layer includes a liquid crystal layer.

[0020] On the other hand, this embodiment provides a driving method for a microstrip filter as shown above, including: applying a voltage to at least one patch in a patch array, changing the dielectric constant of the dielectric layer between the at least one patch and the stub, so as to control the resonant frequency between the at least one patch and the microstrip line.

[0021] On the other hand, this embodiment provides an electronic device including the microstrip filter as described above.

[0022] On the other hand, this embodiment provides an indoor distribution system, including the microstrip filter as described above.

[0023] In some exemplary embodiments, an indoor distributed antenna system includes: an indoor distributed signal source module, an intermediate module, and an indoor distributed antenna module; the intermediate module is connected between the indoor distributed signal source module and the indoor distributed antenna module. The illustrated indoor distributed antenna module includes a filtering and mixing unit and multiple antennas, the filtering and mixing unit being connected to the intermediate module and the multiple antennas, and the filtering and mixing unit including at least one of the aforementioned microstrip filters.

[0024] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0025] The accompanying drawings are provided to further understand the technical solutions of this disclosure and constitute a part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of this disclosure and do not constitute a limitation on the technical solutions of this disclosure.

[0026] Figure 1 This is a schematic diagram of the structure of a microstrip filter according to at least one embodiment of the present disclosure;

[0027] Figure 2 for Figure 1 A partial cross-section along the Q-Q' direction;

[0028] Figure 3 This is a plan view of the first substrate according to at least one embodiment of the present disclosure;

[0029] Figure 4 This is a plan view of the second substrate according to at least one embodiment of the present disclosure;

[0030] Figure 5A and Figure 5B This is a schematic diagram of the simulation results of a microstrip filter according to at least one embodiment of the present disclosure;

[0031] Figure 6 This is another schematic diagram of a microstrip filter according to at least one embodiment of the present disclosure;

[0032] Figure 7 This is another schematic diagram of a microstrip filter according to at least one embodiment of the present disclosure;

[0033] Figure 8 This is another schematic diagram of a microstrip filter according to at least one embodiment of the present disclosure;

[0034] Figure 9 This is a schematic diagram of the structure of an indoor distribution system according to at least one embodiment of the present disclosure;

[0035] Figure 10 This is a schematic diagram of an indoor distribution signal source module according to at least one embodiment of the present disclosure;

[0036] Figure 11This is another schematic diagram of an indoor distribution signal source module according to at least one embodiment of the present disclosure;

[0037] Figure 12 This is a schematic diagram of the filtering and mixing unit of an indoor distributed antenna module according to at least one embodiment of the present disclosure;

[0038] Figure 13 Another schematic diagram of the filtering and mixing unit of an indoor distributed antenna module according to at least one embodiment of the present disclosure;

[0039] Figure 14 This is a schematic diagram of an electronic device according to at least one embodiment of the present disclosure. Detailed Implementation

[0040] The embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The implementation can be carried out in many different forms. Those skilled in the art will readily understand that the methods and content can be changed to one or more forms without departing from the spirit and scope of this disclosure. Therefore, this disclosure should not be construed as limited to the content described in the following embodiments. Without conflict, the embodiments and features in the embodiments of this disclosure can be arbitrarily combined with each other.

[0041] In the accompanying drawings, the size of one or more constituent elements, the thickness of layers, or areas are sometimes exaggerated for clarity. Therefore, this disclosure is not necessarily limited to these dimensions, and the shapes and sizes of the various components in the drawings do not reflect true proportions. Furthermore, the drawings schematically illustrate ideal examples, and this disclosure is not limited to the shapes or values ​​shown in the drawings.

[0042] The ordinal numbers such as "first," "second," and "third" in this disclosure are used to avoid confusion among the constituent elements, not to limit the quantity. The term "multiple" in this disclosure refers to two or more quantities.

[0043] In this disclosure, for convenience, terms such as "middle," "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer" are used to indicate orientation or positional relationships in conjunction with the accompanying drawings. This is solely for the purpose of facilitating the description and simplification of the specification, and does not imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this disclosure. The positional relationships of the constituent elements may be appropriately changed depending on the direction in which the constituent elements are described. Therefore, the description is not limited to the terms used in the specification and may be appropriately replaced as appropriate.

[0044] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection via an intermediate component, or a connection within two components. Those skilled in the art will understand the meaning of these terms in this disclosure as appropriate.

[0045] In this disclosure, "electrical connection" includes the situation where constituent elements are connected together by a component having a certain electrical function. There are no particular limitations on the "component having a certain electrical function," as long as it enables the transmission of electrical signals between the connected constituent elements. Examples of "component having a certain electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other components having one or more functions.

[0046] In this disclosure, "parallel" refers to a state in which the angle formed by two straight lines is greater than or equal to -10° and less than 10°, and therefore can include a state in which the angle is greater than or equal to -5° and less than 5°. Furthermore, "perpendicular" refers to a state in which the angle formed by two straight lines is greater than or equal to 80° and less than 100°, and therefore can include a state in which the angle is greater than or equal to 85° and less than 95°.

[0047] In this disclosure, "about" and "approximately" refer to values ​​that are not strictly defined and are within the allowable range of process and measurement errors. In this disclosure, "identical" can include cases of complete consistency and approximately identical values; "approximately identical" means values ​​that differ by less than 10%.

[0048] This embodiment provides a microstrip filter, electronic device, and indoor distribution system, which can realize integrated and low-cost filter design.

[0049] This embodiment provides a microstrip filter, including: a first substrate and a second substrate disposed opposite to each other, and a dielectric layer located between the first substrate and the second substrate. The first substrate includes: a first substrate and a patch array disposed on the side of the first substrate near the dielectric layer. The second substrate includes: a second substrate, a microstrip line disposed on the side of the second substrate near the dielectric layer, and a ground layer disposed on the side of the second substrate away from the microstrip line. The microstrip line includes: a main transmission line and at least one stub. The stub of the microstrip line overlaps with the orthographic projection of the patch array onto the first substrate. 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 patches of the patch array.

[0050] The microstrip filter provided in this embodiment achieves a bandpass effect by setting the microstrip line stubs to overlap with the patch array in the orthographic projection of the first substrate, and by applying voltage to the patches in the patch array to change the dielectric constant of the dielectric layer, thereby controlling the resonant frequency between the overlapping patches and the microstrip line stubs in the orthographic projection.

[0051] 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 patches and microstrip lines 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: lead zirconate titanate (PZT) film, barium calcium zirconate titanate (BZT) film, barium strontium titanate (BST) film, etc. This embodiment is not limited to this.

[0052] In some exemplary embodiments, the microstrip line may include multiple stubs, and these stubs may be symmetrically arranged about the main transmission line. For example, the microstrip line may include eight stubs, and these eight stubs may be symmetrically arranged about the main transmission line. By employing a symmetrical arrangement of stubs, this example allows the radiation characteristics generated between the stubs on both sides of the main transmission line and the patch array to cancel each other out, thereby preventing electromagnetic radiation leakage and avoiding interference with external devices.

[0053] In some exemplary embodiments, the microstrip line may include multiple stubs, and these stubs may be connected to the same side of the main transmission line. For example, the microstrip line may include four stubs, and these four stubs may be connected to the same side of the main transmission line. This example uses an asymmetrical arrangement of stubs to limit electromagnetic radiation while ensuring that the distance between the patch array and the ground plane is sufficiently close and the thickness of the first and second substrates is small (e.g., much less than 1 / 10 of the wavelength).

[0054] In some exemplary embodiments, the patch array may include multiple types of patches, with patches of the same type having 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 using multiple types of patches, this example allows the microstrip filter to achieve different frequency responses. The resonant frequency between the patch and the microstrip line can be controlled by applying voltage to one or more types of patches to achieve the desired filter effect.

[0055] In some exemplary embodiments, the orthographic projection of at least one stub of the microstrip line onto the first substrate and the orthographic projection of multiple patches of the patch array onto the first substrate may overlap, and the multiple patches overlapping the same stub may belong to different types. In some examples, the multiple patches overlapping the orthographic projection of the same stub onto the first substrate may be arranged in ascending order of size, moving away from the main transmission line. The patch array arrangement in this example can help ensure the effectiveness of the microstrip filter.

[0056] In some exemplary embodiments, at least one type of patch may have a slotted region. The orthographic projection of the slotted region onto the first substrate may overlap with the orthographic projection of the microstrip line stubs onto the first substrate. In some examples, the orthographic projection of the slotted region onto the first substrate may be rectangular. For example, the orthographic projection of at least one type of patch onto the first substrate may be a rectangular ring. This example, by providing a slotted region on the patch, increases the radial side length of the patch overlapping with the stubs, which is beneficial for reducing the size of the patch array.

[0057] In some exemplary embodiments, the first substrate may further include: multiple driving electrode lines disposed on the first substrate, with multiple patches of the same type connected to the same driving electrode line. Since whether a voltage is applied to the patch affects the switching on and off at the corresponding frequency, this example, by using the same driving voltage to control patches of the same type, can achieve a narrower frequency band for the response frequency and thus a better switching effect. However, this embodiment is not limited to this. In other examples, multiple patches of the same type can be connected to different driving electrode lines, and by applying different voltages to patches of the same type, the isolation can be easily weakened.

[0058] The following examples illustrate the solution of this embodiment.

[0059] Figure 1 This is a schematic diagram of the structure of a microstrip filter according to at least one embodiment of the present disclosure. Figure 2 for Figure 1 A partial cross-sectional view along the Q-Q' direction. In some examples, such as... Figure 1 and Figure 2 As shown, the microstrip filter of this example may include: a first substrate 11 and a second substrate 12 disposed 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 liquid crystal material. The first substrate 11 and the second substrate 12 may be disposed in a cell to form a liquid crystal cell, and the dielectric layer 13 may be disposed in the liquid crystal cell. However, this embodiment is not limited thereto. In other examples, the dielectric layer may include at least one of the following: lead zirconate titanate (PZT) film, barium calcium zirconate titanate (BZT) film, barium strontium titanate (BST) film, etc.

[0060] In some examples, such as Figure 2 As shown, a support structure 14 can be provided between the first substrate 11 and the second substrate 12. The support structure 14 can be generally an annular structure surrounding the periphery of the first substrate 11 and the second substrate 12. The support structure 14 may include a sealing adhesive and spacers (or isolation pillars). By providing the support structure, a cavity can be formed between the first substrate 11 and the second substrate 12, and a liquid crystal layer located between the first substrate 11 and the second substrate 12 can be formed by filling the cavity with liquid crystal material. However, this embodiment is not limited to this. In this example, by providing the support structure, the gap between the first substrate and the second substrate can be maintained, which is beneficial to maintaining the uniformity of the liquid crystal layer and preventing the cavity from collapsing and affecting the thickness uniformity of the liquid crystal layer.

[0061] Figure 3 This is a plan view of a first substrate according to at least one embodiment of the present disclosure. In some examples, such as... Figures 1 to 3 As shown, 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 the side of the first substrate 110 closer to the dielectric layer 13. The patch array may include a plurality of patches 111 arranged in an array. 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 the second direction Y; for example, the first direction X may be perpendicular to the second direction Y.

[0062] In some examples, such as Figure 3 As shown, the first substrate 11 may further include multiple driving electrode lines 113a and 113b located on the first substrate 110. Multiple patches 111 of the patch array can be electrically connected to the multiple driving electrode lines. For example, the multiple patches 111 and the multiple driving electrode lines 113a and 113b can be electrically connected in a one-to-one correspondence. For example, the patches 111 and the connected driving electrode lines can be an integrally connected structure.

[0063] In some examples, such as Figure 3As shown, the first substrate 11 may further include multiple drive transmission lines 114a and 114b located on the first substrate 110 and extending along the first direction X. The multiple drive transmission lines 114a and 114b may be arranged on both sides of the edge region of the patch array in the second direction Y. The multiple drive transmission lines 114a and multiple drive electrode lines 113a may be electrically connected, and the multiple drive transmission lines 114b and multiple drive electrode lines 113b may be electrically connected. For example, the multiple drive electrode lines and multiple drive transmission lines may be electrically connected in a one-to-one correspondence. 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 integral structure interconnected. 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.

[0064] In some examples, the patch array may include: multiple types of patches. Patches of the same type may have the same shape and size, while patches of different types may have at least one different shape and size. For example, different types of patches may have the same shape but different sizes, or different types of patches may have different shapes and sizes. One type of patch may correspond to one 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 uses three types of patches (e.g., Figure 3 The first type patch 111a, the second type patch 111b, and the third type patch 111c are used as examples for illustration. The microstrip filter in this example can correspond to three resonant center frequencies.

[0065] In some examples, each type of patch can have a slotted region. For example, a first type patch 111a can have a first slotted region 1110a, a second type patch 111b can have a second slotted region 1110b, and a third type patch 111c can have a third slotted region 1110c. The first slotted region 1110a, the second slotted region 1110b, and the third slotted region 1110c can all be approximately rectangular in their orthographic projection onto the first substrate 110. The dimensions of the first slotted region 1110a, the second slotted region 1110b, and the third slotted region 1110c can increase sequentially.

[0066] In some examples, such as Figure 3 As shown, the shapes of the first type patch 111a, the second type patch 111b, and the third type patch 111c in the orthographic projection of the first substrate 1110 can all be rectangular rings. The size of the first type patch 111a can be smaller than the size of the second type patch 111b, and the size of the second type patch 111b can be smaller than the size of the third type patch 111c.

[0067] Figure 4 This is a plan view of a second substrate according to at least one embodiment of the present disclosure. In some examples, such as... Figures 1 to 4 As shown, the second substrate 12 may include: a second substrate 120, microstrip lines 121 disposed on opposite sides of the second substrate 120, and a ground layer 122. The microstrip lines 121 may be located on the side of the second substrate 120 closer to the dielectric layer 13, and the ground layer 122 may be located on the side of the second substrate 120 away from the dielectric layer 13. The ground layer 122 may be a full-surface metal layer, and the orthographic projection of the ground layer 122 onto the second substrate 120 may cover the orthographic projection of the microstrip lines 121 onto the second substrate 120. This example utilizes the microstrip lines 121, the second substrate 120, and the ground layer 122 to form a microstrip transmission structure.

[0068] In some examples, such as Figure 4 As shown, the microstrip line 121 may include a main transmission line 1211 and at least one stub 1212. The shape of the main transmission line 1211 in the orthographic projection of the second substrate 120 may be a strip structure extending along a first direction X. One end of the main transmission line 1211 may be connected to a first port 15a, and the other end of the main transmission line 1211 may be connected to a second port 15b. The first port 15a and the second port 15b may be the input port and output port of a microstrip filter. This embodiment does not limit the type and arrangement of the first and second ports.

[0069] In some examples, the microstrip line 121 may include multiple stubs 1212, such as eight stubs 1212. The multiple stubs 1212 and the main transmission line 1211 can be an interconnected integral structure. The shape of a single stub 1212 in its orthographic projection onto the second substrate 120 can be approximately a strip extending along the second direction Y. The extension direction of the stub 1212 can be perpendicular to the extension direction of the main transmission line 1211. In this example, the eight stubs 1212 can be symmetrically arranged about the main transmission line 1211. The dimensions of the eight stubs 1212 can be approximately the same. The spacing between adjacent stubs 1212 can be approximately the same. The microstrip line 121 can be approximately symmetrical about the centerline of the first direction X, and also approximately symmetrical about the centerline of the second direction Y. In this example, the stubs of the microstrip line can be arranged symmetrically. Due to the symmetrical design on both sides, the surface current directions of the patch array are opposite, causing the generated radiation characteristics to cancel each other out and avoiding interference to external devices.

[0070] In some examples, the orthographic projection of each branch 1212 of the microstrip line 121 onto the first substrate 110 may overlap with the orthographic projection of the patch array onto the first substrate 110, while the orthographic projection of the main transmission line 1211 onto the patch array may not overlap. The patch array may be arranged approximately symmetrically about the main transmission line 1211. In this example, the patch array may be arranged in six rows and four columns. The main transmission line 1211 may be arranged in three rows and four columns on one side of the second direction Y, and also in three rows and four columns on the opposite side of the second direction Y. Multiple patches in the same row may have the same size and belong to the same type; multiple patches in the same column may have different sizes and belong to different types.

[0071] In some examples, the orthographic projection of each branch 1212 onto the first substrate 110 overlaps with the orthographic projection of a column of patches (including three different types of patches, namely, a first type patch 111a, a second type patch 111b, and a third type patch 111c) onto the first substrate 110. The three patches overlapping the orthographic projection of each branch 1212 onto the first substrate 110 can be arranged sequentially in ascending order of size, moving away from the main transmission line 1211. The first type patches 111a, the second type patches 111b, and the third type patches 111c located in the same column can be aligned in the second direction Y, and the three types of patches can coincide along the centerline of the first direction X. The centerline of the three types of patches along the first direction X can substantially coincide with the centerline of the overlapping branch 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 stub onto the first substrate can be arranged sequentially in descending order of size away from the main transmission line. In still other examples, multiple patches of the patch array can be nested; for example, a first type of patch can be located within a second slot region of a second type of patch, or a second type of patch can be located within a third slot region of a third type of patch.

[0072] In some examples, such as Figure 2 As shown, the first substrate 11 may further include a first alignment layer 112 located on the side of the patch array near the dielectric layer 13. The second substrate 12 may further include a second alignment layer 123 located on the side of the microstrip line 121 near the dielectric layer 13. In this example, by providing the first and second alignment layers, the liquid crystal molecules in the dielectric layer can be aligned, causing the liquid crystal molecules to align in a certain direction.

[0073] In some examples, the microstrip filter of this example employs a double-sided metallization process on the second substrate to form a microstrip transmission structure. The liquid crystal molecules in the liquid crystal layer, as anisotropic materials, have different dielectric constants along their long and short axes. When a deflection voltage is applied to both ends of the liquid crystal molecules, they deflect, and the dielectric constant of the liquid crystal material changes with the deflection. By applying voltage to the patches of the patch array, the resonant frequency between the patches and the overlapping microstrip transmission structure can be adjusted using liquid crystal deflection. The dielectric constant of the liquid crystal molecules in the liquid crystal layer corresponding to each patch and microstrip transmission structure can be independently controlled and changed. When a voltage is applied to the corresponding patch through the driving electrode lines, liquid crystal deflection can be used to achieve resonance between the patch and the overlapping microstrip transmission structure at a non-center frequency, allowing the center frequency signal corresponding to the patch to pass through, forming a bandpass effect. When no voltage is applied to the patch through the driving electrode lines, the patch and the overlapping microstrip transmission structure resonate at the center frequency, causing the center frequency signal corresponding to the patch to be turned off, forming a bandstop effect. In this example, the liquid crystal layer is configured to control the on / off state of the resonant center frequencies corresponding to the patches. In some examples, the number of patch types can determine the number of tunable center frequencies of the microstrip filter. One type of patch corresponds to one tunable center frequency, and different types of patches can correspond to different center frequencies. In some examples, the number of stubs in the microstrip line can determine the bandwidth corresponding to the tunable center frequency. The more stubs in the microstrip line, and the more patches of the same type overlapping with the stubs, the greater the bandwidth corresponding to the center frequency of that type of patch, thus improving the filtering effect. The fewer stubs in the microstrip line, and the fewer patches of the same type overlapping with the stubs, the smaller the bandwidth corresponding to the center frequency of that type of patch.

[0074] In some examples, the driving voltage applied to the patches of the patch array can depend on the material and thickness of the dielectric layer. The driving voltage can be less than 30V. For example, the dielectric layer can be a liquid crystal layer, and the driving voltage can be less than or equal to 8V.

[0075] Figure 5A and Figure 5B This is a schematic diagram of the simulation results of a microstrip filter according to at least one embodiment of the present disclosure. Figure 5A The image shows the pair. Figure 1 Simulation results of the first type of patch array of microstrip filters after applying voltage. Figure 5B The image shows the pair. Figure 1 The simulation results of the first type of patch array of microstrip filters without applied voltage are shown.

[0076] In some examples, the first type of patch can be 10.5 mm long and 5 mm wide; 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 second type of patch can be 23 mm long and 8 mm wide; the length and width of the second slotted area of ​​the second type of patch are 10 mm and 0.8 mm, respectively. The second type of patch can correspond to 0.74 GHz to 0.76 GHz. The third type of patch can be 23 mm long and 10 mm wide; the length and width of the third slotted area of ​​the third type of patch are 20 mm and 0.8 mm, respectively; 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 approximately 1.6 mm, the width of the stub (i.e., the length along the first direction X) can be approximately 4 mm, the length of the stub (i.e., the length along the second direction Y) can be approximately 72 mm, and the spacing between adjacent stubs can be approximately 28 mm. The thickness of the liquid crystal layer can be approximately 20 micrometers (µm).

[0077] In some examples, Figure 5A and Figure 5B A comparison was made regarding whether the 2.5GHz to 2.6GHz bands could pass the test. Figure 5A The diagram shows the case where voltage is applied to the first type of patch, while voltage is not applied to the second and third type of patches. Figure 5B The diagram shows the case where no voltage is applied to the first type, second type, and third type of surface mount devices. Figure 5A As can be seen, when a voltage is applied to the first type of patch, signals from 2.5 GHz to 2.6 GHz can pass through, creating a bandpass effect. Figure 5B As can be seen, when the voltage applied to the first type of patch is removed, the loss reaches 30dB in the 2.5GHz to 2.6GHz range, which is equivalent to the signal not passing through in that section, creating a band-stop effect. This example demonstrates how controlling the voltage applied to the corresponding type of patch can achieve signal switching. In some examples, the number of patch types can be rationally designed based on the number of frequencies to be multiplexed.

[0078] The following is an illustrative example of the fabrication process of a microstrip filter. The "patterning process" described in this disclosure includes, for metallic, inorganic, or transparent conductive materials, processes such as photoresist coating, mask exposure, development, etching, and photoresist stripping; for organic materials, it includes processes such as organic material coating, mask exposure, and development. Deposition can be performed using any one or more of sputtering, evaporation, and chemical vapor deposition; coating can be performed using any one or more of spraying, spin coating, and inkjet printing; etching can be performed using any one or more of dry etching and wet etching. This disclosure does not limit the methods used. A "thin film" refers to a thin film made of a material on a substrate using deposition, coating, or other processes. If the "thin film" does not require a patterning process during the entire fabrication process, it can also be called a "layer." If the "thin film" requires a patterning process during the entire fabrication 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."

[0079] The phrase "A and B are set on the same layer" in this disclosure means that A and B are formed simultaneously through the same patterning process. In the exemplary embodiments of this 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.

[0080] In some exemplary embodiments, the fabrication process of a microstrip filter may include the following operations.

[0081] (1) Fabrication of a first substrate. In some examples, a wiring layer and a first conductive layer are sequentially formed on the first substrate. For example, a wiring thin film is coated on the first substrate, and a wiring layer is formed by a patterning process; subsequently, a first conductive thin film is coated to form a first conductive layer. The first conductive layer can be made of a metal material with good conductivity, such as copper (Cu). The first conductive layer may include a patch array. The wiring layer can be made of a metal material or a transparent conductive material, such as indium tin oxide (ITO). The wiring layer may include multiple driving electrode lines, or multiple driving electrode lines and multiple driving transmission lines.

[0082] In some examples, a first alignment film may be coated on a first substrate forming the aforementioned pattern, the first alignment film may be cured, and the cured first alignment film may be 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.

[0083] (2) Fabrication of the 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 can be made of a metallic material with good conductivity, such as copper (Cu). The second conductive layer may include microstrip lines. A ground layer can be formed on the side of the second substrate away from the second conductive layer by deposition. The orthographic projection of the ground layer onto the second substrate may include the orthographic projection of the second conductive layer onto the second substrate.

[0084] In some examples, a second alignment film can be coated on a second substrate forming the aforementioned pattern, the second alignment film can be cured, and the cured second alignment film can be aligned using an alignment technique to obtain a transparent second alignment layer. The second alignment layer can cover the second conductive layer.

[0085] In some examples, alignment techniques may include rubbing alignment and ultraviolet light alignment. These techniques create trenches on the surface of the first alignment layer to align liquid crystal molecules, causing them to align in a specific direction. The first alignment film can be made of polyimide, polyamide, polyethylene, polystyrene, or polyvinyl alcohol. However, this embodiment is not limited to these materials.

[0086] In some examples, the first and second substrates can be rigid substrates, such as glass substrates. Using rigid substrates to form the liquid crystal cell allows for precise control of the cell thickness, ensuring uniform thickness. Furthermore, microstrip filters based on glass substrates are easier to mass-produce, which helps reduce device complexity and cost.

[0087] (3) Align the first substrate and the second substrate to prepare the liquid crystal cell.

[0088] In some examples, a sealant is applied around the periphery of the first or second substrate. The first and second substrates are then aligned and assembled. The sealant is cured to form a support structure between the first and second substrates. A cavity is formed by the first substrate, the second substrate, and the support structure. Multiple crystal filling ports can be sequentially arranged on the support structure. Liquid crystal material is poured through these ports to form a liquid crystal layer as a dielectric layer.

[0089] In this example, the stubs and patches of the microstrip line can constitute the upper and lower electrodes for controlling the operation of the liquid crystal layer. Utilizing the electrically tunable 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 to the patches, creating a voltage difference between the patches and the stubs, thereby changing the arrangement of the liquid crystal molecules and achieving the effect of adjusting the resonant frequency.

[0090] The microstrip filter provided in this example can be designed on a glass substrate using semiconductor thin-film technology, incorporating multiple tunable units (i.e., patches and stub structures with interposed liquid crystal layers) to achieve adjustable resonant frequencies. By applying voltage, the resonant frequencies of these tunable units can be controlled, enabling different frequency responses for the same tunable unit. Furthermore, the combined control of multiple tunable units achieves the desired filter effect. Since the tunable units in this example can be controlled by applying voltage to achieve different frequency responses, different combinations of voltage applications can be used to control different filtering effects, thereby simplifying the design and reducing costs.

[0091] Figure 6 This is another schematic diagram of a microstrip filter according to at least one embodiment of the present disclosure. In some examples, such as Figure 6 As shown, the patch array can be symmetrically arranged about the main transmission line of the microstrip line 121. In the patch array located on one side of the main transmission line, patches of the same type can be electrically connected to the same drive electrode line 113a or 113b. For example, a row of patches of the same type can be electrically connected to the same drive electrode line 113a or 113b. Further descriptions of the microstrip filter in this example can be found in the description of the foregoing embodiments, and will not be repeated here.

[0092] In this example, since the presence or absence of applied voltage affects the switching on and off at the corresponding frequency, applying a uniform voltage to patches of the same type can narrow the bandwidth of the response frequency, resulting in better switching performance. However, this embodiment is not limited to this. In other examples, different voltages can be applied to patches of the same type, which can widen the bandwidth of the response frequency and weaken the switching isolation.

[0093] Figure 7 This is another schematic diagram of a microstrip filter according to at least one embodiment of the present disclosure. In some examples, such as Figure 7 As shown, the orthographic projection of patch 111 in the patch array onto the first substrate can be rectangular. The patch array in this example can include three types of patches, all of which can have rectangular orthographic projections onto the substrate, but with different dimensions. Patches of the same type can be electrically connected to the same drive electrode line 113a or 113b. For example, a row of patches of the same type can be electrically connected to the same drive electrode line 113a or 113b. Further descriptions of the microstrip filter in this example can be found in the description of the foregoing embodiments, and will not be repeated here.

[0094] In this example, when the area of ​​the microstrip filter is not limited, a solid patch can be used to achieve the filtering effect.

[0095] Figure 8 This is another schematic diagram of a microstrip filter according to at least one embodiment of the present disclosure. In some examples, such as Figure 8As shown, the microstrip line 121 may include four stubs, and the four stubs are connected to the same side of the main transmission line. The patch array may include three rows and four columns. Further descriptions of the microstrip filter in this example can be found in the description of the foregoing embodiments, and will not be repeated here.

[0096] In this example, the stubs 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 plane is close enough and the thickness of the first and second substrates is small (e.g., much less than 1 / 10 of the wavelength).

[0097] This embodiment also provides a driving method for a microstrip filter, applied to the microstrip filter 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 stub, thereby controlling the resonant frequency between at least one patch and the microstrip line.

[0098] In some examples, the patch array includes multiple types of patches. By applying voltage to multiple patches of the same type, signals corresponding to the resonant center frequency of that type of patch can pass through, creating a bandpass effect. The desired filtering effect can be achieved by combining and controlling whether voltage is applied to multiple types of patches. The control unit (e.g., equipped with a control program) can provide voltage signals to the corresponding patches via drive electrode lines, and control the resonant frequency by controlling the voltage applied to the corresponding patches to achieve the desired filtering effect.

[0099] The driving method of the microstrip filter in this embodiment can be referred to the description of the foregoing embodiment, and therefore will not be repeated here.

[0100] This embodiment also provides an indoor distribution system, including the microstrip filter described above.

[0101] In some examples, with the development and maturation of 5G technology, indoor users are increasingly demanding high-bandwidth, high-transmission capabilities. Millimeter-wave-based digital indoor distribution systems (DAS) are limited by technology and cost, and have not yet achieved commercialization. The relatively mature traditional distributed antenna systems (DAS) cannot handle higher data volumes. Therefore, reusing and expanding traditional DAS systems becomes a better solution. The two main technical approaches are active frequency conversion DAS systems and passive frequency conversion DAS systems. Both approaches divide and convert a single 5G signal, transmit it, and then convert it back to the original frequency, distinguishing it from the original frequency through different polarization forms to achieve multiple-input multiple-output (MIMO) functionality and thus expand capacity. However, any frequency conversion scheme involves frequency conversion, matching, and filtering components, typically using discrete devices, low-temperature co-fired ceramics (LTCC), and dielectric filters. This leads to a series of problems such as customized design, high cost, and large size.

[0102] The indoor distribution system of this embodiment can use the microstrip filter provided in the previous embodiment. The resonant frequency can be controlled by applying voltage, and the filter effect can be achieved by combining and controlling the patches that require the applied voltage. Since the patch control that requires the applied voltage can be controlled by a program, different filtering functions can be achieved. By utilizing the aforementioned microstrip filter, the indoor distribution system of this embodiment can simplify the complexity of system design and reduce the cost of system modification.

[0103] The following example illustrates the indoor distribution system used in this case.

[0104] Figure 9 This is a schematic diagram of the structure of an indoor distribution system according to at least one embodiment of the present disclosure. In some examples, such as... Figure 9 As shown, the indoor distributed antenna system in this example may include: an indoor distributed signal source module 31, an intermediate module 32, and an indoor distributed antenna module 33. The indoor distributed signal source module 31 can be configured to provide wireless signals as input to the system. For example, the wireless signals provided by the indoor distributed signal source module 31 may include: a radio frequency signal RF1 (e.g., 900MHz), a radio frequency signal RF2 (e.g., 1800MHz / 2GHz / 2.3GHz / 2.6GHz), a local oscillator signal LO (e.g., 1100MHz), and an intermediate frequency signal IF (e.g., 1500MHz). Multiple wireless signals can be combined using a combiner and then connected to the intermediate module 32 via a single cable.

[0105] In some examples, the intermediate module 32 receives the wireless signal provided by the indoor distribution source module 31 via a cable, and then amplifies, distributes, and manages the wireless signal to enhance coverage and capacity in the indoor area. For example, the intermediate module 32 may include a power divider, a feeder, and a coupler.

[0106] In some examples, the output signal of the intermediate module 32 can be provided to the indoor distributed antenna module 33. The indoor distributed antenna module 33 can provide high-quality wireless signal coverage and transmission in indoor environments. The indoor distributed antenna module 33 may include a filtering and mixing unit and multiple antennas. The filtering and mixing unit can be connected to the intermediate module 32 and the multiple antennas. The filtering and mixing unit can filter and mix the output signal of the intermediate module 32 to obtain multiple wireless signals, which are then radiated through the multiple antennas.

[0107] Figure 10 This is a schematic diagram of an indoor distribution source module according to at least one embodiment of the present disclosure. In some examples, such as Figure 10 As shown, for radio frequency (RF) signals RF1 and RF2 in a multi-channel wireless signal stream, after receiving the wireless signals, they can be sequentially processed through digital-to-analog (DA) conversion, mixing, filtering, and amplification before being combined using a combiner. The original 2.6GHz signal in the source section is split into two paths. One path uses a 2.6GHz carrier for transmission and is combined after DA conversion, mixing, filtering, and amplification. The other path, after DA conversion, mixing, and filtering, is mixed with the local oscillator signal to become an intermediate frequency (IF) signal. This IF signal is then filtered and amplified before being combined with other wireless signals. The local oscillator signal, after amplification, is combined with other signals. In this example, the processing units for local oscillator, mixing, filtering, and amplification in the indoor distributed antenna system (DAS) source module can all be integrated inside the source device. After being combined using a combiner, the signals are connected to the intermediate module via a single cable.

[0108] Figure 11 This is another schematic diagram of an indoor distribution source module according to at least one embodiment of the present disclosure. In some examples, such as Figure 11 As shown, radio frequency signals RF1 and RF2 can be sequentially converted from digital to analog, mixed, filtered, and amplified before being combined and transmitted through the first combiner. The original 2.6GHz signal in the source section can be split 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. The second path, after digital-to-analog conversion, mixing, and filtering, is mixed with the local oscillator signal to become an intermediate frequency (IF) signal. This IF signal, after filtering and amplification, is then combined with other wireless signals through the second combiner. The mixing, filtering, and amplification units for the second 2.6GHz signal can be packaged separately (e.g.,...). Figure 11The external unit (shown by the dashed box) is connected to the source device integrated with the remaining radio frequency signals. In some examples, the filter within the external unit can be a microstrip filter provided in the aforementioned embodiments, which can simplify the design and reduce costs.

[0109] The indoor distribution system in this example splits one 2.6GHz signal from the source section into two paths. One path still uses the 2.6GHz carrier for transmission, while the other path is converted into an intermediate frequency signal for transmission through a mixer. This eliminates the need to change the intermediate system, ensuring extremely low retrofit costs.

[0110] Figure 12 This is a schematic diagram of the filtering and mixing unit of an indoor distributed antenna module according to at least one embodiment of the present disclosure. In some examples, such as Figure 12 As shown, the input port of the indoor distributed antenna module can receive the output signal from the intermediate module. After receiving the signal, the indoor distributed antenna module uses multiple filters (e.g., filters F1, F2, F3, and F4) to obtain the local oscillator (LO) signal, intermediate frequency (IF) signal, radio frequency (RF) signal RF1, and radio frequency (RF) signal RF2. In the filtering and mixing unit, the IF signal can be re-converted to 2.6 GHz. Specifically, the IF signal is mixed with the output of the matched balun B1 and the output of the local oscillator (LO) signal after being mixed with the matched balun B1. The output of the mixer is then processed by the matched balun B3 and filter F5 to obtain a single 2.6 GHz signal. The antenna can use different polarizations to radiate the 2.6 GHz signal in RF2 and the converted 2.6 GHz signal, thereby achieving MIMO multi-stream capability.

[0111] In some examples, Figure 12 At least one of the filters F1, F2, F3, F4 and F5 in the filter mixing unit shown can be a microstrip filter as described in the foregoing embodiments. The patch in the microstrip filter that requires the applied voltage can be controlled by program coding, and a voltage can be applied to the corresponding patch to achieve different filtering effects.

[0112] This example uses microstrip filters, as described in the previous embodiment, in all or part of the filters in the filtering and mixing unit of the indoor distribution system. By controlling the filtering effect of the corresponding microstrip filters through different codes, the required types of filters and devices can be reduced, which helps to reduce the design complexity and modification cost of the system.

[0113] Figure 13 This is another schematic diagram of the filtering and mixing unit of an indoor distributed antenna module according to at least one embodiment of the present disclosure. In some examples, such as Figure 13As shown, the addition of filters and mixers to the indoor distributed antenna module for frequency conversion of the intermediate frequency (IF) signal leads to additional attenuation of the IF signal, resulting in an imbalance of the multi-input multi-output (MIMO) signal. Therefore, an amplifier is added to amplify the converted signal after mixing the local oscillator (LO) signal and the IF signal to ensure that the levels of the two 2.6 GHz signals (the original 2.6 GHz and the converted 2.6 GHz) are equivalent. However, this embodiment is not limited to this approach. 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 signals (the original 2.6 GHz and the converted 2.6 GHz) are equivalent.

[0114] In some examples, Figure 13 At least one of the filters F1, F2, F3, F4 and F5 in the filter mixing unit shown can be a microstrip filter as described in the foregoing embodiments. The patch in the microstrip filter that requires the applied voltage can be controlled by program coding, and a voltage can be applied to the corresponding patch to achieve different filtering effects.

[0115] The indoor distribution system in this example, by employing the microstrip filter as described above, can reduce the variety of components required for the entire system, thereby reducing system upgrade costs and simplifying the design, thus reducing system design complexity.

[0116] Figure 14 This is a schematic diagram of an electronic device according to at least one embodiment of the present disclosure. Figure 14 As shown, this embodiment provides an electronic device 91, including a microstrip filter 910 as described in the previous embodiment and a control unit. The control unit can control the voltage application method of the patch array of the microstrip filter 910 (i.e., which patches are voltage-applied and which patches are not voltage-applied), thereby controlling the resonant frequency between the corresponding patches and stubs to achieve the corresponding filtering effect.

[0117] In some examples, electronic device 91 can be any product or component with communication capabilities, such as a mobile phone, navigation device, game console, television (TV), car audio system, tablet computer, personal multimedia player (PMP), or personal digital assistant (PDA). However, this embodiment is not limited to this.

[0118] The accompanying drawings in this disclosure only illustrate the structures relevant to this disclosure; other structures can be referenced to common designs. Unless otherwise specified, the embodiments of this 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 embodiments or implementation methods are merely exemplary and not restrictive. Therefore, this disclosure is not limited to what is shown and described in detail herein. Various modifications, substitutions, or omissions can be made to the form and details of the implementation without departing from the scope of this disclosure.

Claims

1. A microstrip filter, comprising: A first substrate and a second substrate disposed opposite to each other, and a dielectric layer located between the first substrate and the second substrate; The first substrate includes: a first substrate and a patch array disposed on the side of the first substrate near the dielectric layer; The second substrate includes: a second substrate, a microstrip line disposed on the side of the second substrate near the dielectric layer, and a ground layer disposed on the side of the second substrate away from the microstrip line; the microstrip line includes: a main transmission line and at least one stub; The stubs of the microstrip line overlap with the orthographic projection of the patch array onto 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 patches of the patch array.

2. The microstrip filter according to claim 1, wherein, The microstrip line includes multiple branches, which are symmetrically arranged about the main transmission line.

3. The microstrip filter according to claim 2, wherein, The microstrip line includes eight stubs, which are symmetrically arranged about the main transmission line.

4. The microstrip filter according to claim 1, wherein, The microstrip line includes multiple stubs, and the multiple stubs are connected to the same side of the main transmission line.

5. The microstrip filter according to claim 4, wherein, The microstrip line includes four stubs, and the four stubs are connected to the same side of the main transmission line.

6. The microstrip filter according to claim 1, wherein, The extension direction of the stub of the microstrip line is perpendicular to the extension direction of the main transmission line.

7. The microstrip filter according to any one of claims 1 to 6, wherein, The patch array includes multiple types of patches, with patches of the same type having the same shape and size; each type of patch corresponds to a tunable center frequency.

8. The microstrip filter according to claim 7, wherein, The orthographic projection of at least one branch of the microstrip line onto the first substrate overlaps with the orthographic projection of multiple patches of the patch array onto the first substrate, and the multiple patches that overlap with the same branch belong to different types.

9. The microstrip filter according to claim 8, wherein, Multiple patches that overlap with the orthographic projection of the same branch onto the first substrate are arranged in order of increasing size away from the main transmission line.

10. The microstrip filter according to claim 7, wherein, At least one type of patch has a slotted region, the orthographic projection of which overlaps with the orthographic projection of the microstrip line stubs on the first substrate.

11. The microstrip filter according to claim 10, wherein, The grooved area is a rectangle when projected onto the first substrate.

12. The microstrip filter according to claim 7, wherein, At least one type of patch has a rectangular orthographic projection onto the first substrate.

13. The microstrip filter according to claim 7, wherein, The first substrate further includes: multiple driving electrode lines disposed on the first substrate, and multiple patches of the same type connected to the same driving electrode line.

14. The microstrip filter according to claim 1, wherein, The first substrate further includes: a first alignment layer located on the side of the patch array near the dielectric layer; the second substrate further includes: a second alignment layer located on the side of the microstrip line near the dielectric layer.

15. The microstrip filter according to claim 1, wherein, The dielectric layer includes a liquid crystal layer.

16. A driving method for a microstrip filter as described in 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 stub, thereby controlling the resonant frequency between the at least one patch and the microstrip line.

17. An electronic device comprising a microstrip filter as claimed in any one of claims 1 to 15.

18. An indoor distribution system comprising a microstrip filter as claimed in any one of claims 1 to 15.

19. The indoor distribution system according to claim 18, comprising: The system includes an indoor distributed signal source module, an intermediate module, and an indoor distributed antenna module; the intermediate module is connected between the indoor distributed signal source module and the indoor distributed antenna module. The indoor distributed antenna module shown includes a filtering and mixing unit and multiple antennas. The filtering and mixing unit is connected to the intermediate module and the multiple antennas. The filtering and mixing unit includes at least one of the microstrip filters.

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