CN113097669B - Tunable filter - Google Patents
Tunable filter Download PDFInfo
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- CN113097669B CN113097669B CN202110412221.XA CN202110412221A CN113097669B CN 113097669 B CN113097669 B CN 113097669B CN 202110412221 A CN202110412221 A CN 202110412221A CN 113097669 B CN113097669 B CN 113097669B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P3/00—Waveguides; Transmission lines of the waveguide type
- H01P3/02—Waveguides; Transmission lines of the waveguide type with two longitudinal conductors
- H01P3/08—Microstrips; Strip lines
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Abstract
The invention discloses a tunable filter, and belongs to the technical field of filters. It includes: the upper surface of the first dielectric substrate is provided with a microstrip circuit; the second dielectric substrate is connected to the lower surface of the first dielectric substrate, a slotted floor and a plurality of metal through holes are arranged on the second dielectric substrate, a gap between every two adjacent metal through holes is arranged on the slotted floor, and the gap and the microstrip circuit have an overlapping part; the plurality of ground patches are arranged on the lower surface of the second medium substrate in a one-to-one correspondence manner, and the metal through holes are respectively connected with the slotted floor and the ground patches; the microstrip patch is arranged on the lower surface of the second dielectric substrate and positioned between the two adjacent ground patches, and the microstrip patch and the gap have an overlapping part; and the switch diodes in the same conduction state and the same cut-off state are respectively arranged between the microstrip patch and the grounding patch. The tunable filter can realize the switching between the through state and the filtering state and reduce the insertion loss.
Description
Technical Field
The invention relates to the technical field of filters, in particular to a tunable filter.
Background
The filter is widely applied to the field of radar and communication, wherein the tunable filter is used in the occasion of adjusting the working frequency or bandwidth, the function of the tunable filter is mainly to realize the switching between the filtering state and the through state, the circuit structure for realizing the switching between the filtering state and the through state in the prior art is shown in figure 1, the circuit structure specifically adopts a filter 1 and a through section 2 which are connected in parallel, single-pole double-throw switches are respectively connected at two ends of the filter 1 and the through section 2, the two single-pole double-throw switches are respectively a first single-pole double-throw switch 10 and a second single-pole double-throw switch 11, the through state and the filtering state are realized by switching the first single-pole double-throw switch 10 and the second single-pole double-throw switch 11, but in the circuit structure shown in figure 1, when the microwave passes through, the insertion loss comprises the loss of the two single-pole double-throw switches, and the insertion loss is increased, for example, a microwave signal of 2dBm is input to a single-pole double-throw switch, 1dBm is output, and 1dB is lost. Thus, there is a need for a tunable filter that can switch between a pass-through state and a filter state and reduce insertion loss.
Disclosure of Invention
It is an object of the present invention to overcome at least one of the above-mentioned deficiencies of the prior art and to provide a tunable filter capable of switching between a through state and a filter state with reduced insertion loss.
The technical scheme for solving the technical problems is as follows: a tunable filter, comprising:
the micro-strip circuit comprises a first dielectric substrate, a second dielectric substrate and a third dielectric substrate, wherein the upper surface of the first dielectric substrate is provided with a micro-strip circuit;
the second dielectric substrate is connected to the lower surface of the first dielectric substrate and provided with a slotted floor, a plurality of metal through holes are formed in the second dielectric substrate at intervals along the length direction of the slotted floor, the upper ends and the lower ends of the metal through holes penetrate out of the second dielectric substrate respectively, the upper ends of the metal through holes are connected with the slotted floor, gaps are formed in the slotted floor and located between every two adjacent metal through holes, and the gaps and the microstrip circuit are provided with overlapped parts in the thickness direction of the first dielectric substrate;
a plurality of ground patches are arranged, the plurality of ground patches correspond to the plurality of metal through holes one by one along the length direction of the slotted floor and are arranged on the lower surface of the second dielectric substrate, and the lower ends of the metal through holes are connected with the ground patches;
the microstrip patch is arranged on the lower surface of the second dielectric substrate and positioned between two adjacent ground patches, the microstrip patch and the gap have an overlapping part in the thickness direction of the second dielectric substrate, and a gap I and a gap II are respectively formed between the microstrip patch and the two adjacent ground patches;
a plurality of switch diodes are arranged, the switch diodes are respectively arranged in the first gap and the second gap, two pins of the switch diodes are respectively connected with the microstrip patch and the grounding patch, and the conduction state and the cut-off state of the switch diodes are the same at the same time point;
when the switch diodes are all cut off, electromagnetic waves between the microstrip circuit and the slotted floor can leak from the slot, the slot and the microstrip patch arranged corresponding to the slot form a resonance unit, and the resonance unit is in a resonance state and forms a stop band for the electromagnetic waves at the resonance frequency of the resonance unit;
when the switch diodes are all conducted, the grounding patch, the microstrip patch, the switch diode and the slotted floor can form a complete floor, and the microstrip circuit and the complete floor form a microstrip transmission structure capable of transmitting microwave signals in full frequency bands.
The invention has the beneficial effects that: in this embodiment, a microstrip circuit is disposed on the upper side of a first dielectric substrate, a slotted floor is disposed on the upper side of a second dielectric substrate, a slot is disposed on the slotted floor, in addition, a ground patch, a microstrip patch and a switching diode are further disposed on the lower side of the second dielectric substrate, when the switching diode is turned off, electromagnetic waves between the microstrip circuit and the slotted floor can leak from the slot, the slot and the microstrip patch disposed corresponding to the slot form a resonance unit, and the resonance unit is in a resonance state and forms a stop band for the electromagnetic waves at a resonance frequency of the resonance unit, so that the tunable filter in this embodiment achieves a filtering state; when the switch diodes are all conducted, the grounding patch, the microstrip patch, the switch diode and the slotted floor can form a complete floor, the microstrip circuit and the complete floor form a microstrip transmission structure capable of transmitting microwave signals in full frequency band, and the microwave signals can be transmitted in full frequency band, so that the tunable filter in the embodiment realizes a through state; therefore, compared with the tunable filter in the prior art, the tunable filter in the embodiment can be switched between the through state and the filtering state by switching the double-throw switches without respectively arranging the double-throw switches at two ends of the tunable filter, and the loss of the two double-throw switches can be saved in the filtering state, so that the tunable filter in the embodiment can be switched between the through state and the filtering state and reduce the insertion loss.
In addition, on the basis of the above technical solution, the present invention may be further improved as follows, and may further have the following additional technical features.
According to an embodiment of the invention, a plurality of the slots are arranged and are respectively located between two adjacent metal via holes, and a plurality of the micro-strip patches are arranged along the length direction of the slotted floor in a one-to-one correspondence manner. In this embodiment, by providing a plurality of slits, when the switching diodes are all cut off, the plurality of slits form a plurality of resonance units, and the resonance frequencies of each resonance unit are sequentially staggered, which is beneficial for the tunable filter to have a stop band characteristic in a relatively wide frequency range in a filtering state.
According to one embodiment of the invention, the thickness of the first dielectric substrate is 0.25-1.5 mm. The thickness of the first dielectric substrate in the embodiment is 0.25-1.5mm, the first dielectric substrate is convenient to process and form, the manufacturing cost of the tunable filter is reduced, and when the second dielectric substrate is connected to the first dielectric substrate, the distance between the microstrip circuit and the slotted floor is suitable.
According to one embodiment of the invention, the thickness of the second dielectric substrate is 0.05-0.2 mm. In this embodiment, the thickness of the second dielectric substrate is 0.05-0.2mm, and the thickness of the second dielectric substrate is suitable, so that the distance between the microstrip patch and the slotted floor is small, and it is ensured that the microstrip patch reliably blocks the electromagnetic waves leaking from the slot when the switching diodes are all turned on.
According to one embodiment of the invention, a plurality of the metal via holes are arranged at equal intervals, a plurality of the ground patches are arranged at equal intervals, and a plurality of the slots are arranged at equal intervals. In this embodiment, it is a plurality of metal via hole equidistance interval sets up, and is a plurality of ground patch equidistance interval sets up, and is a plurality of gap equidistance interval sets up for tunable filter can satisfy the stop band demand of broad and improve the stop band effect.
According to an embodiment of the present invention, the slot is symmetrically disposed with a center of the microstrip circuit as a center of symmetry, and the microstrip patch is symmetrically disposed with the center of the slot as a center of symmetry. In this embodiment, the slots are symmetrically arranged with the center of the microstrip circuit as a symmetric center, and the microstrip patches are symmetrically arranged with the center of the slots as a symmetric center, so that the microstrip circuit, the slots and the microstrip patches have more overlapping parts, and when the tunable filter is in a through state, the blocking effect of the microstrip patches on electromagnetic waves leaked from the slots is improved.
According to one embodiment of the present invention, the plurality of slots have the same or different shapes, the plurality of microstrip patches have the same or different shapes, and the plurality of ground patches have the same or different shapes. In the embodiment, the shapes of the slot, the microstrip patch and the grounding patch are respectively the same, so that the structure of the tunable filter can be simplified and the tunable filter is convenient to process; in addition, the shapes of the slot, the microstrip patch, and the ground patch in the present embodiment may be set to be different, respectively, as necessary.
According to an embodiment of the present invention, the length of the second dielectric substrate is equal to the length of the first dielectric substrate, the width of the second dielectric substrate is equal to the width of the first dielectric substrate, and the length of the slotted floor is equal to the length of the microstrip circuit. In this embodiment, the length of the second dielectric substrate is equal to the length of the first dielectric substrate, the width of the second dielectric substrate is equal to the width of the first dielectric substrate, and the length of the slotted floor is equal to the length of the microstrip circuit, which is beneficial to fully utilizing the length and width dimensions of the first dielectric substrate and the second dielectric substrate and reducing the volume of the tunable filter; in addition, the length of the slotted floor in the embodiment is equal to that of the microstrip circuit, which is beneficial to fully utilizing the length dimensions of the microstrip circuit and the slotted floor.
According to an embodiment of the present invention, the plurality of slots, the plurality of metal vias, the plurality of microstrip patches, and the plurality of ground patches are arranged in a line shape at intervals. In this embodiment, the plurality of slots, the plurality of metal via holes, the plurality of microstrip patches, and the plurality of ground patches are arranged in a line shape at intervals, so that the structure of the tunable filter can be simplified, the tunable filter is convenient to process, and the stop band effect of the tunable filter can be improved.
According to one embodiment of the invention, the tunable filter further comprises: and the prepreg is arranged between the second dielectric substrate and the first dielectric substrate, and the second dielectric substrate is bonded on the lower surface of the first dielectric substrate through the prepreg. In this embodiment, the second dielectric substrate is bonded to the lower surface of the first dielectric substrate through the prepreg, so that the second dielectric substrate and the first dielectric substrate are tightly attached and connected into a whole.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a prior art circuit configuration diagram for implementing the functions of filter state and pass-through state switching;
FIG. 2 is a schematic structural diagram of a tunable filter according to an embodiment of the present invention;
FIG. 3 is a top view of the first dielectric substrate of FIG. 2 after alignment;
FIG. 4 is a top view of the second dielectric substrate of FIG. 2 after being straightened;
fig. 5 is a bottom view of the second dielectric substrate of fig. 2 after being straightened.
In the drawings, the components represented by the respective reference numerals are listed below:
1. the filter comprises a filter 2, a through section 3, a first dielectric substrate 4, a second dielectric substrate 5, a switch diode 10, a first single-pole double-throw switch 11, a second single-pole double-throw switch 30, a microstrip circuit 40, a slotted floor 41, a grounding patch 42, a microstrip patch 401, a metal via hole 402 and a slot.
Detailed Description
To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.
The present embodiment provides a tunable filter, as shown in fig. 2 to 5, including:
a first dielectric substrate 3, wherein a microstrip circuit 30 is arranged on the upper surface of the first dielectric substrate 3;
the second dielectric substrate 4 is connected to the lower surface of the first dielectric substrate 3, the second dielectric substrate 4 is provided with a seam floor 40, a plurality of metal through holes 401 are arranged on the second dielectric substrate 4 at intervals along the length direction of the seam floor 40, the upper ends and the lower ends of the plurality of metal through holes 401 respectively penetrate out of the second dielectric substrate 4, the upper ends of the metal through holes 401 are connected with the seam floor 40, a gap 402 is arranged on the seam floor 40, the gap 402 is located between every two adjacent metal through holes 401, and the gap 402 and the microstrip circuit 30 are provided with an overlapping part in the thickness direction of the first dielectric substrate 3;
a plurality of ground patches 41 are arranged, a plurality of metal through holes 401 corresponding to the ground patches 41 one by one along the length direction of the slotted floor 40 are arranged on the lower surface of the second dielectric substrate 4, and the lower ends of the metal through holes 401 are connected with the ground patches 41;
the microstrip patch 42 is arranged on the lower surface of the second dielectric substrate 4 and located between the two adjacent ground patches 41, the microstrip patch 42 and the slot 402 have an overlapping portion in the thickness direction of the second dielectric substrate 4, and a first gap and a second gap are respectively formed between the microstrip patch 42 and the two adjacent ground patches 41;
a plurality of switch diodes 5, the switch diodes 5 are respectively installed in the first gap and the second gap, two pins of the switch diodes 5 are respectively connected with the microstrip patch 42 and the grounding patch 41, and the conduction state and the cut-off state of the switch diodes 5 are the same at the same time point;
when the switching diodes 5 are all cut off, electromagnetic waves passing between the microstrip circuit 30 and the slotted floor 40 can leak from the slot 402, the slot 402 and the microstrip patch 42 arranged corresponding to the slot 402 form a resonance unit, and the resonance unit is in a resonance state and forms a stop band for the electromagnetic waves at the resonance frequency of the resonance unit;
when the switch diodes 5 are all turned on, the ground patch 41, the microstrip patch 42, the switch diodes 5 and the slotted floor 40 may form a complete floor, and the microstrip circuit 30 and the complete floor form a microstrip transmission structure capable of transmitting microwave signals in full frequency band.
In the present embodiment, as shown in fig. 2 to 5, by providing the microstrip circuit 30 on the upper side surface of the first dielectric substrate 3, providing the seam floor 40 on the upper side surface of the second dielectric substrate 4, and providing the seam 402 on the seam floor 40, and further providing the ground patch 41, the microstrip patch 42, and the switching diode 5 on the lower side surface of the second dielectric substrate 4, when the switching diode 5 is turned off, the electromagnetic wave passing between the microstrip circuit 30 and the seam floor 40 can leak from the seam 402, the seam 402 and the microstrip patch 42 provided corresponding thereto form a resonance unit, and the resonance unit is in a resonance state and forms a stop band for the electromagnetic wave at the resonance frequency of the resonance unit, so that the tunable filter in the present embodiment achieves a filtering state; when the switching diodes 5 are all turned on, the ground patch 41, the microstrip patch 42, the switching diode 5 and the slotted floor 40 can form a complete floor, the microstrip circuit 30 and the complete floor form a microstrip transmission structure capable of transmitting microwave signals in full frequency band, and the microwave signals can be transmitted in full frequency band, so that the tunable filter in the embodiment realizes a through state; therefore, compared with the tunable filter in the prior art, the tunable filter in the embodiment can be switched between the through state and the filtering state by switching the double-throw switches without respectively arranging the double-throw switches at two ends of the tunable filter, and the loss of the two double-throw switches can be saved in the filtering state, so that the tunable filter in the embodiment can be switched between the through state and the filtering state and reduce the insertion loss. Further, in this embodiment, the resonant frequency of the tunable filter is adjusted by the number of the microstrip patches 42 and the size of the slot 402, and the number of the microstrip patches 42 and the size of the slot 402 can be set appropriately according to the stop band requirement of the tunable filter.
In this embodiment, the first dielectric substrate 3 is specifically a dielectric copper clad laminate, the second dielectric substrate 4 is also a dielectric copper clad laminate, the materials of the first dielectric substrate 3 and the second dielectric substrate 4 are mainly composite dielectric materials, the microstrip circuit 30 is formed by photoetching and etching on the first dielectric substrate 3, and the slotted floor 40, the ground patch 41 and the microstrip patch 42 are formed by photoetching and etching on the second dielectric substrate 4. Further, the materials of the first dielectric substrate 3 and the second dielectric substrate 4 in this embodiment may also be ceramic rigid materials, the microstrip circuit 30 is formed by depositing a metal conduction band on the first dielectric substrate 3, and the slotted floor 40, the ground patch 41, and the microstrip patch 42 are formed by depositing a metal conduction band on the second dielectric substrate 4. Further, the materials of the first dielectric substrate 3 and the second dielectric substrate 4 in this embodiment may also be other dielectric base materials; further, the slotted floor 40 in this embodiment specifically belongs to a microstrip circuit structure, and the microstrip patch 42 and the ground patch 41 in this embodiment both belong to metal patches; further, two pins of the switching diode 5 in this embodiment are respectively soldered to the microstrip patch 42 and the ground patch 41 on two sides thereof.
In this embodiment, as shown in fig. 2 to 5, the first dielectric substrate 3 and the second dielectric substrate 4 are both rectangular, the microstrip circuit 30 is disposed along the length direction of the first dielectric substrate 3, the tunable filter in this embodiment is a symmetric structure, the input end and the output end at the left and right ends of the tunable filter are respectively connected to the coaxial line, specifically, the inner conductor of the coaxial line is welded on the microstrip circuit 30, and the outer conductor of the coaxial line is welded on the slotted floor 40; further, the microstrip circuit 30 and the complete floor in this embodiment form a microstrip transmission structure, specifically a microstrip transmission line, capable of transmitting microwave signals in full frequency band.
In this embodiment, it should be noted that the "microstrip circuit 30" in this embodiment is equivalent to a conductor strip of a microstrip transmission line in the prior art, and the structure and function of the "complete floor" are equivalent to a floor of a microstrip transmission line in the prior art, where the floor is a microstrip metal flat plate, and after a microwave signal is transmitted to the first dielectric substrate 3 through a coaxial line, a magnetic field can be formed between the microstrip circuit 30 and the slotted floor 40; further, "having an overlapping portion" in this embodiment includes the case of partial overlapping and full overlapping, and the overlapping condition of the slot 402, the microstrip circuit 30 and the microstrip patch 42 can ensure that the tunable filter can realize the through state and the filtering state switching; further, in this embodiment, "the ground patch 41, the microstrip patch 42, the switching diode 5, and the slotted floor 40 may form a complete floor" means that the microstrip patch 42 makes up the slot 402 on the slotted floor 40, so that the slotted floor 40 has a floor function; further, the width of the microstrip circuit 30 in this embodiment may be set as required, and the sizes of the first gap and the second gap in this embodiment may be various, so that the switching diode 5 may be conveniently disposed in the first gap and the second gap.
In an embodiment of the present invention, as shown in fig. 2 and 4, a plurality of slots 402 are provided, and the plurality of slots 402 are respectively located between two adjacent metal vias 401, and a plurality of microstrip patches 42 are provided corresponding to the plurality of slots 402 one by one along the length direction of the slotted floor 40.
In this embodiment, as shown in fig. 2 and 4, in this embodiment, four slots 402 and four microstrip patches 42 are provided, and when the switching diodes 5 are all turned off, the four slots 402 and the four microstrip patches 42 form four resonance units, and the resonance frequencies of each resonance unit are sequentially staggered, which is beneficial for the tunable filter to exhibit a stop-band characteristic in a relatively wide frequency range in a filtering state. Further, the number of the slots 402 and the number of the microstrip patches 42 may also be two, three or more, and correspondingly, the number of the metal via holes 401 may be three, four or more, and the specific number of the metal via holes 401, the slots 402, the microstrip patches 42 and the ground patches 41 is selected according to the stop band requirement of the tunable filter. Furthermore, only one resonance unit may be provided in this embodiment, and the number of the resonance units may be set to 1-10 according to the stop band requirement of the tunable filter.
In one embodiment of the present invention, the thickness of the first dielectric substrate 3 is 0.25-1.5 mm. In this embodiment, the thickness of the first dielectric substrate 3 is 0.25-1.5mm, which is convenient for processing and forming the first dielectric substrate 3, and is beneficial to reducing the manufacturing cost of the tunable filter, and when the second dielectric substrate 4 is connected to the first dielectric substrate 3, the space between the microstrip circuit 30 and the slotted floor 40 is ensured to be suitable. Further, the thickness of the first dielectric substrate 3 in this embodiment is preferably 0.508mm, but the thickness of the first dielectric substrate 3 may also be set to any value of 0.25-1.5mm, for example, 0.762mm, etc., according to the requirement.
In one embodiment of the present invention, the thickness of the second dielectric substrate 4 is 0.05-0.2 mm. In this embodiment, the thickness of the second dielectric substrate 4 is 0.05-0.2mm, and the thickness of the second dielectric substrate 4 is suitable, so that the distance between the microstrip patch 42 and the slotted floor 40 is small, and it is ensured that the microstrip patch 42 reliably blocks the electromagnetic waves leaking from the slot 402 when the switching diodes 5 are all turned on, and in addition, the thickness of the second dielectric substrate 4 is suitable for facilitating production and obtaining of the second dielectric substrate 4. Further, the thickness of the second dielectric substrate 4 in the present embodiment is preferably about 0.1mm, the thickness of the second dielectric substrate 4 in the present embodiment is 0.127mm, and the thickness of the second dielectric substrate 4 may be set to any value of 0.25 to 1.5mm as required.
In one embodiment of the present invention, as shown in fig. 2, 4 and 5, the plurality of metal vias 401 are disposed at equal intervals, the plurality of ground patches 41 are disposed at equal intervals, and the plurality of slots 402 are disposed at equal intervals. In this embodiment, a plurality of metal via holes 401 are equidistantly spaced, a plurality of ground patches 41 are equidistantly spaced, and a plurality of slots 402 are equidistantly spaced, so that the tunable filter can meet the wider stop band requirement and improve the stop band effect. The structure size of the metal via 401 in this embodiment may be appropriately set according to requirements, the distance values between the plurality of metal vias 401 may have a plurality of values, in addition, the distance values between the plurality of slots 402 may also have a plurality of values, the distance values between the plurality of ground patches 41 may have a plurality of values, the distances between the plurality of metal vias 401 may also be set to be unequal, in addition, the distances between the plurality of metal vias 401 may also be set to be unequal, the distances between the plurality of ground patches 41 may also be set to be unequal, the distances between the plurality of slots 402 may also be set to be unequal, which is not described in detail herein. In this embodiment, five metal via holes 401 are provided, five ground patches 41 are provided, four slots 402 are provided, and four microstrip patches 42 are provided, and in addition, the values set by the metal via holes 401, the ground patches 41, the slots 402, and the microstrip patches 42 in this embodiment may have various combinations, which is not described herein again.
In one embodiment of the present invention, as shown in fig. 2 to 5, the slot 402 is symmetrically disposed with the center of the microstrip circuit 30 as the center of symmetry, and the microstrip patch 42 is symmetrically disposed with the center of the slot 402 as the center of symmetry. In this embodiment, the slot 402 is symmetrically disposed with the center of the microstrip circuit 30 as the center of symmetry, and the microstrip patch 42 is symmetrically disposed with the center of the slot 402 as the center of symmetry, so that the microstrip circuit 30, the slot 402 and the microstrip patch 42 have more overlapping portions, and when the tunable filter is in a through state, the effect of blocking the electromagnetic wave leaked from the slot 402 by the microstrip patch 42 is improved. Furthermore, the arrangement of the slot 402 in this embodiment may be various, and when the slot 402 deviates from the center of the microstrip circuit 30 backward or forward, the stop-band effect of the tunable filter is slightly poor, but the implementation of the function of the tunable filter is not affected; in addition, when the microstrip patch 42 is offset from the center of the slot 402, there is no influence when the tunable filter is in the through state, and when the tunable filter is in the filtering state, the effect of blocking the electromagnetic wave leaking from the slot 402 by the microstrip patch 42 is inferior to the effect of blocking the electromagnetic wave when the microstrip patch 42 is symmetrically disposed with the center of the slot 402 as the center of symmetry.
In one embodiment of the present invention, as shown in fig. 2 to 5, the plurality of slots 402 have the same shape, the plurality of microstrip patches 42 have the same shape, and the plurality of ground patches 41 have the same shape. In this embodiment, the slot 402, the microstrip patch 42, and the ground patch 41 are formed in the same shape, so that the tunable filter can be simplified in structure and can be easily manufactured. Further, the slit 402 in this embodiment is a long strip-shaped structure, and the slit 402 may also be configured as a wave-shaped structure; the microstrip patch 42 in this embodiment is rectangular, and the ground patch 41 may be formed in other shapes as well as the microstrip patch 42 having a rectangular shape and the ground patch 41 having a rectangular shape.
Further, in the present embodiment, the shapes of the slot 402, the microstrip patch 42, and the ground patch 41 in the present embodiment may be set to be different, as necessary. For example, a certain slit 402 is provided in a long stripe shape, and another slit 402 is provided in an arc shape, or the like; similarly, the microstrip patch 42 and the ground patch 41 may have various structures, and when the tunable filter is in a filtering state, the microstrip patch 42 may possibly block the electromagnetic wave leaking from the slot 402. In this embodiment, the configuration in which the slot 402, the microstrip patch 42, and the ground patch 41 of the tunable filter are provided in different shapes is not illustrated.
In one embodiment of the present invention, as shown in fig. 2, the length of the second dielectric substrate 4 is equal to the length of the first dielectric substrate 3, the width of the second dielectric substrate 4 is equal to the width of the first dielectric substrate 3, and the length of the slotted floor 40 is equal to the length of the microstrip circuit 30. In this embodiment, the length of the second dielectric substrate 4 is equal to the length of the first dielectric substrate 3, the width of the second dielectric substrate 4 is equal to the width of the first dielectric substrate 3, and the length of the slotted floor 40 is equal to the length of the microstrip circuit 30, which is beneficial to fully utilizing the length and width dimensions of the first dielectric substrate 3 and the second dielectric substrate 4 and reducing the volume of the tunable filter; in addition, the length of the slotted floor 40 in the embodiment is equal to the length of the microstrip circuit 30, which is beneficial to fully utilizing the length dimensions of the microstrip circuit 30 and the slotted floor 40. It should be noted that the length of the slotted floor 40 and the length of the microstrip circuit 30 in this embodiment may also be set to be unequal, in which case, the length of the slotted floor 40 or the microstrip circuit 30 may be increased by coaxial connection; further, the length of the second dielectric substrate 4 and the length of the first dielectric substrate 3 may be set to be unequal, and the width of the second dielectric substrate 4 and the width of the first dielectric substrate 3 may be set to be unequal.
In one embodiment of the present invention, as shown in fig. 2, 4 and 5, the plurality of slots 402, the plurality of metal vias 401, the plurality of microstrip patches 42 and the plurality of ground patches 41 are arranged in a straight line shape at intervals. In this embodiment, the plurality of slots 402, the plurality of metal vias 401, the plurality of microstrip patches 42 and the plurality of ground patches 41 are all arranged in a straight line shape at intervals, so that the structure of the tunable filter can be simplified, the tunable filter is convenient to process, and the stop band effect of the tunable filter can be improved. Further, the plurality of slots 402 in this embodiment may not be arranged at intervals in a straight line, and the relative positions between the slots 402 may be adjusted within a certain range, so that the function of the tunable filter can be normally implemented; similarly, the plurality of metal vias 401, the plurality of microstrip patches 42, and the plurality of ground patches 41 in this embodiment may not be arranged at intervals in a straight line, and the arrangement of the plurality of metal vias 401, the plurality of microstrip patches 42, and the plurality of ground patches can normally realize the function of the tunable filter. Further, the metal via 401 in this embodiment is connected to the middle position of the ground patch 41, so that the ground patch 41 is connected to the metal via 401, and the metal via 401 is connected to other positions of the ground patch 41.
In one embodiment of the invention, the tunable filter further comprises: and the prepreg is arranged between the second dielectric substrate 4 and the first dielectric substrate 3, and the second dielectric substrate 4 is bonded on the lower surface of the first dielectric substrate 3 through the prepreg. In this embodiment, the second dielectric substrate 4 is bonded to the lower surface of the first dielectric substrate 3 through a prepreg, so that the second dielectric substrate 4 and the first dielectric substrate 3 are tightly attached and connected into a whole. Further, the second dielectric substrate 4 in this embodiment may also be pressed and attached to the first dielectric substrate 3 into a whole through a metal shell. Note that the prepreg in this example is not illustrated.
In addition to the technical solutions disclosed in the present embodiment, for the other structures of the microstrip circuit 30, the ground patch 41, the microstrip patch 42, the switching diode 5, the prepreg, the microstrip transmission line, the filter, and the working principle thereof, etc., reference may be made to conventional technical solutions in the technical field, which are not the important points of the present invention, and the present invention is not set forth herein in detail.
In the present invention, the term "plurality" means two or more unless explicitly defined otherwise. The terms "mounted," "connected," "fixed," and the like are to be construed broadly, and for example, "connected" may be a fixed connection, a removable connection, or an integral connection; "coupled" may be direct or indirect through an intermediary. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or unit must have a specific direction, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
In the description herein, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A tunable filter, comprising:
the micro-strip circuit comprises a first dielectric substrate, a second dielectric substrate and a third dielectric substrate, wherein the upper surface of the first dielectric substrate is provided with a micro-strip circuit;
the second dielectric substrate is connected to the lower surface of the first dielectric substrate and provided with a slotted floor, a plurality of metal through holes are formed in the second dielectric substrate at intervals along the length direction of the slotted floor, the upper ends and the lower ends of the metal through holes penetrate out of the second dielectric substrate respectively, the upper ends of the metal through holes are connected with the slotted floor, gaps are formed in the slotted floor and located between every two adjacent metal through holes, and the gaps and the microstrip circuit are provided with overlapped parts in the thickness direction of the first dielectric substrate;
a plurality of ground patches are arranged, the plurality of ground patches correspond to the plurality of metal through holes one by one along the length direction of the slotted floor and are arranged on the lower surface of the second dielectric substrate, and the lower ends of the metal through holes are connected with the ground patches;
the microstrip patch is arranged on the lower surface of the second dielectric substrate and positioned between two adjacent ground patches, the microstrip patch and the gap have an overlapping part in the thickness direction of the second dielectric substrate, and a gap I and a gap II are respectively formed between the microstrip patch and the two adjacent ground patches;
a plurality of switch diodes are arranged, the switch diodes are respectively arranged in the first gap and the second gap, two pins of the switch diodes are respectively connected with the microstrip patch and the grounding patch, and the conduction state and the cut-off state of the switch diodes are the same at the same time point;
when the switch diodes are all cut off, electromagnetic waves between the microstrip circuit and the slotted floor can leak from the slot, the slot and the microstrip patch arranged corresponding to the slot form a resonance unit, and the resonance unit is in a resonance state and forms a stop band for the electromagnetic waves at the resonance frequency of the resonance unit;
when the switch diodes are all conducted, the grounding patch, the microstrip patch, the switch diode and the slotted floor can form a complete floor, and the microstrip circuit and the complete floor form a microstrip transmission structure capable of transmitting microwave signals in full frequency bands.
2. The tunable filter of claim 1, wherein a plurality of the slots are provided, and the plurality of the slots are respectively located between two adjacent metal vias, the plurality of the microstrip patches are provided along a length direction of the slotted floor, and the plurality of the microstrip patches are provided in a one-to-one correspondence with the plurality of the slots.
3. The tunable filter of claim 1, wherein the first dielectric substrate has a thickness of 0.25-1.5 mm.
4. The tunable filter of claim 1, wherein the second dielectric substrate has a thickness of 0.05-0.2 mm.
5. The tunable filter of any one of claims 2 to 4, wherein a plurality of the metal vias are equidistantly spaced apart, a plurality of the ground patches are equidistantly spaced apart, and a plurality of the slots are equidistantly spaced apart.
6. The tunable filter of any one of claims 1 to 4, wherein the slot is symmetrically disposed about a center of symmetry of the microstrip circuit, and the microstrip patch is symmetrically disposed about the center of symmetry of the slot.
7. The tunable filter of any one of claims 2 to 4, wherein the slots are the same or different in shape, the microstrip patches are the same or different in shape, and the ground patches are the same or different in shape.
8. The tunable filter of any one of claims 1 to 4, wherein the length of the second dielectric substrate is equal to the length of the first dielectric substrate, the width of the second dielectric substrate is equal to the width of the first dielectric substrate, and the length of the slotted floor is equal to the length of the microstrip circuit.
9. The tunable filter of any one of claims 2 to 4, wherein the plurality of slots, the plurality of metal vias, the plurality of microstrip patches and the plurality of ground patches are all arranged in a straight line at intervals.
10. The tunable filter of any one of claims 1 to 4, further comprising:
and the prepreg is arranged between the second dielectric substrate and the first dielectric substrate, and the second dielectric substrate is bonded on the lower surface of the first dielectric substrate through the prepreg.
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| CN104821420A (en) * | 2015-04-24 | 2015-08-05 | 华南理工大学 | Reconfigurable dual-band band-stop filter |
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| DE102013017296A1 (en) * | 2013-10-18 | 2015-04-23 | IAD Gesellschaft für Informatik, Automatisierung und Datenverarbeitung mbH | Variable microstrip bandpass filter based on coupled λ / 4 resonators |
| CN111600101A (en) * | 2020-05-09 | 2020-08-28 | 中国人民武装警察部队工程大学 | Broadband filter with adjustable notch |
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