TW201814954A - Filter structure - Google Patents

Abstract

The invention provides a filter structure. The filter structure comprises a base body, a plurality of resonance metallic layers, a grounding metallic layer, a metallic pattern layer, an input electrode and an output electrode. The base body has a plurality of resonance holes with an end located at an open surface and another end located at a short surface. The resonance metallic layers are provided in the resonance holes. The grounding metallic layer is provided on the short surface, a top surface, a bottom surface and two side surfaces of the base body to form a short end by connecting electrically with the resonance metallic layers. The input electrode and the output electrode are provided on the bottom surface of the base body or the open surface without connecting electrically to the grounding metallic layer. An electrical characteristic of mutual coupling filter is formed by the metallic pattern layer, the resonance metallic layers and the grounding metallic layer for adjusting the length of the resonance metallic layer and the required band of the metallic pattern layer.

Description

Filter structure improvement

The present invention relates to a filter, and more particularly to a filter structure improvement having a surface adhesion that changes the frequency response.

Surface-adhesive filters are known to be widely used in wave concentrators (LNBs), satellite navigation systems (GPS), and WIFI systems. The filter is used in these wireless communication systems to filter out the noise contained in the signal received by the wireless communication system to ensure the quality of the communication system signal transmission and reception.

The current filter has a carrier having a plurality of resonant holes extending through the carrier, one end of the resonant holes being on the open surface, and the other end being on the short-circuited surface, on the short-circuited surface and the top of the carrier The face, the bottom surface and the two sides are covered with an outer conductive layer to form the ground of the filter. In addition, the inner conductive layer is formed in the resonant holes to form a resonator, and the inner conductive layer and the outer conductive layer are electrically connected to form a short-circuit end, and the resonant hole located on the open surface forms an open end. Further, an input pad and an output pad are formed on the bottom surface, and a gap is formed between the input pad and the output pad and the outer conductive layer. The input pad is soldered to the circuit board when the filter is soldered to the circuit board. The output pad provides signal input and output, and the outer conductive layer on the bottom surface is grounded to the circuit board.

The pattern design approved on the surface of the filter mentioned above will be different for different communication systems, and if the pattern on the surface of the filter is not properly designed, it will affect the characteristics of the filter.

Therefore, the main object of the present invention is to improve the characteristics of the filter structure. Therefore, the present invention provides a metal pattern layer on the open surface to increase the overall coupling capacitance of the filter structure to achieve the required frequency band, and also provides It has a low insertion loss and an out-band rejection.

Another object of the present invention is that a single resonant aperture on a filter consists of two or two apertures of different shapes, which can reduce the size of the filter to increase the Q value of the filter structure and suppress spurious response. (spurious response).

A further object of the present invention is that a single resonant aperture system is composed of two or two different aperture shapes, and the length of the two apertures is unequal in length, the performance of the filter structure can be adjusted, and the filter is improved. The frequency response of the structure.

To achieve the above object, the present invention provides a filter structure improvement comprising: a substrate, a plurality of resonant metal layers, a ground metal layer, a metal pattern layer, an input electrode, and an output electrode. The base body has an open surface, a short circuit surface, a top surface, a bottom surface and two side surfaces. The base body has a plurality of resonant holes, the resonant holes penetrating the base body, and one end of the resonant holes is located on the open surface The other end is located on the short circuit surface. The resonant metal layers are disposed in the resonant holes. The grounding metal layer is disposed on the short-circuiting surface, the top surface, the bottom surface, and the two side surfaces; wherein the grounding metal layer disposed on the short-circuiting surface is electrically connected to the resonant metal layers of the resonant holes a short-circuit end, the resonant metal layer forms an open end on the open surface; and the grounded metal layer has an E-shaped pattern on the bottom surface, and has two bare sides on the two sides of the E-shaped pattern to expose the base An empty area, the two bare areas extending over the open surface. The metal pattern layer is disposed on the open surface and electrically connected to the ground metal layer. The input electrode is disposed in one of the two bare spaces. The output electrode is disposed in the other bare space. The electrical characteristics of the filter structure having the mutual coupling between the metal pattern layer and the resonant metal layer and the ground metal layer can be adjusted by adjusting the length of the resonant metal layer and the metal pattern layer to achieve desired use. Frequency band.

In an embodiment of the invention, the metal pattern layer is composed of a plurality of lines, and is disposed at the intersection of the open surface and the top surface, the bottom surface and the two side surfaces, and two adjacent resonant holes. The plurality of lines are electrically connected to the grounding metal layer; wherein the plurality of lines comprise a first edge, a second edge, a first line, a second line, and a third line.

In an embodiment of the present invention, the first edge line is electrically connected to the grounded metal surface at the intersection of the open surface and the top surface and the two side surfaces, and the second edge line is disposed on the open surface The ground contact of the bottom surface is electrically connected to the ground metal layer.

In an embodiment of the present invention, the first straight line is disposed between the two adjacent resonant holes and electrically connected to the first edge and the second edge; and the second straight line is disposed on the two phases Between the adjacent resonant holes and electrically connected to the first edge and the second edge, wherein a distance is formed on the second line; and the third line is disposed between the two adjacent resonant holes and The first edge line and the second edge line are electrically connected to each other, wherein a gap is formed on the third line, and the gap is located adjacent to the first edge line.

In one embodiment of the present invention, one end of the input electrode is disposed on one of the two bare spaces, and the other end extends on the open surface adjacent to one of the resonant holes.

In one embodiment of the present invention, one end of the output electrode is disposed on the other bare space, and the other end extends on the bare space of the open surface and adjacent to one of the resonant holes.

In an embodiment of the present invention, the metal pattern layer is composed of a plurality of rectangular blocks and a straight line segment, and the rectangular blocks are respectively disposed around the resonant holes on the open surface, and are in the resonant holes. The resonant metal layers are electrically connected, and the rectangular blocks are formed with a gap therebetween; the straight line segments are disposed on one side of the rectangular blocks.

In one embodiment of the present invention, one end of the input electrode and the output electrode is disposed on a bare space of a bottom surface of the substrate, and the other end of the input electrode and the output electrode extend in an L shape on the open surface The first rectangular block and the other side of the fourth rectangular block are adjacent to each other and form a gap.

In an embodiment of the invention, the resonant holes are formed by the elliptical holes of different calibers.

In an embodiment of the invention, the resonant metal layers are disposed on the elliptical holes and the inner walls of the circular holes.

In an embodiment of the invention, the length of the elliptical hole is less than the length of the circular hole.

In an embodiment of the present invention, the metal pattern layer is an inverted E shape, and the inverted E shape is electrically connected to the ground metal layer of the top surface and the two side surfaces on one side of the resonant holes; The annular ring portion of the inverted E-shape is disposed on the elliptical hole having a small diameter and electrically connected to the grounded metal layer of the bottom surface.

To achieve the above object, the present invention provides another filter structure improvement, comprising: a substrate, a plurality of resonant metal layers, a ground metal layer, a metal pattern layer, an input electrode, and an output electrode. The base body has an open surface, a short circuit surface, a top surface, a bottom surface and two side surfaces. The base body has a plurality of resonant holes, the resonant holes penetrating the base body, and one end of the resonant holes is located on the open surface The other end is located on the short circuit surface. The resonant metal layers are disposed in the resonant holes. The grounding metal layer is disposed on the short-circuiting surface, the top surface, the bottom surface, and the two side surfaces; wherein the grounding metal layer disposed on the short-circuiting surface is electrically connected to the resonant metal layers of the resonant holes a short-circuit end, the resonant metal layer forms an open end on the open surface; and the grounded metal layer has an E-shaped pattern on the bottom surface, and has two bare sides on the two sides of the E-shaped pattern to expose the base An empty area, the two bare areas extending over the open surface. The metal pattern layer is disposed on the open surface. The input electrode is disposed in one of the two bare spaces. The output electrode is disposed in the other bare space. The electrical characteristics of the filter structure having the mutual coupling between the metal pattern layer and the resonant metal layer and the ground metal layer can be adjusted by adjusting the length of the resonant metal layer and the metal pattern layer to achieve desired use. Frequency band.

In an embodiment of the invention, the resonant holes are formed by the elliptical holes of different calibers.

In an embodiment of the invention, the resonant metal layers are disposed on the elliptical holes and the inner walls of the circular holes.

In an embodiment of the invention, the length of the elliptical hole is less than the length of the circular hole.

In an embodiment of the invention, the metal pattern layer is a straight line segment, and the straight line segment is disposed on one side of the resonant holes.

The technical content and detailed description of the present invention are as follows:

1-3 is a schematic diagram showing the appearance, bottom view and back view of the filter structure of the first embodiment of the present invention. As shown in the figure, the filter structure of the present invention is improved. The filter structure 10 includes: a substrate 1, a plurality of resonant metal layers 2, a grounded metal layer 3, a metal pattern layer 4, an input electrode 5, and an output. Electrode 6. The inner metal layer 2, the ground metal layer 3, the input electrode 5, and the output electrode 6 are coated on the substrate 1 to form a dielectric filter structure. The substrate 1 is made of a ceramic material having a high dielectric constant and has an open surface 11, a short-circuit surface 12, a top surface 13, a bottom surface 14, and two side surfaces 15, 16. The base body 1 is provided with a plurality of resonant holes 17 extending through the base body 1. One end of the resonant hole 17 is located on the open surface 11 and an open end is located on the short-circuit surface 12.

The resonant metal layers 2 are disposed on the inner walls of the resonant holes 17 such that the resonant holes 17 form a resonator of the filter structure 10.

The grounding metal layer 3 is disposed on the short-circuit surface 12, the top surface 13, the bottom surface 14, and the two side surfaces 15, 16. The grounding metal layer 3 is electrically connected to the resonant metal layer 2 disposed in the short-circuit surface 12 and the resonant holes 17 to form a short-circuited end, and the resonant metal layer 2 is formed on the open surface 11 to be open. end. In addition, the ground metal layer 3 is formed on the bottom surface 14 in an E-shaped pattern 31, and two bare spaces 141 for exposing the substrate 1 are formed on both sides of the E-shaped pattern 31. The two bare spaces 141 are formed. Extending on the open face 11.

The metal pattern layer 4 is composed of a plurality of lines, and is disposed at the intersection of the open surface 11 and the top surface 13, the bottom surface 14 and the two side surfaces 15, 16 and the two adjacent resonant holes 17 The ground metal layer 3 is electrically connected to each other. The plurality of lines include a first edge 41, a second edge 42, a first line 43, a second line 44, and a third line 45. The first edge line 41 is electrically connected to the ground metal surface 3 at the intersection of the open surface 11 and the top surface 13 and the two side surfaces 15 and 16. The second edge line 42 is electrically connected to the ground metal layer 3 at the interface between the open surface 11 and the bottom surface 14 . The first line 43 is disposed between the two adjacent resonant holes 17 and electrically connected to the first edge 41 and the second edge 42. The second line 44 is disposed between the two adjacent resonant holes 17 and electrically coupled to the first edge 41 and the second edge 42. The second line 44 defines a spacing 441. Further, the third line 45 is disposed between the two adjacent resonant holes 17 and electrically connected to the first edge 41 and the second edge 42. The third line 45 defines a gap 451. The gap 451 is located adjacent to the first edge 41. The first side line 41, the second side line 42, the first line 43, the second line 44, and the third line 45 of the metal pattern layer 4 are arranged on the open surface 11 to have a plurality of bare areas. 111, 112, 113, 114, and the resonant metal layer 2 of the resonant hole 17 and the ground metal layer 3 form an electrical characteristic of the filter structure 10 having mutual coupling, and the length of the resonant metal layer 2 can be adjusted. The metal pattern layer 4 serves to achieve the required bandwidth and provides low insertion loss and out-band rejection.

The input electrode 5 has an upper end that is disposed on the bare space 141 and a other end that extends on the bare space 111 of the open surface 11 and is adjacent to one of the resonant holes 17 . A signal is supplied from the input electrode 5 to the filter structure 10 for filtering processing.

The output electrode 6 has an upper end disposed on the bare space 141 and a other end extending on the bare space 114 of the open surface 11 and adjacent to one of the resonant holes 17. The output of the signal filtered by the filter structure 10 is provided by the output electrode 6.

The filter structure 10 is surface-attached to a circuit board (not shown) by the input electrode 5 of the filter structure 10, the output electrode 6, and the ground metal layer 3 of the bottom surface 14.

Referring to FIG. 4, it is a schematic diagram of the appearance of a filter structure according to a second embodiment of the present invention. As shown in the figure, the filter structure 10 disclosed in the second embodiment is substantially the same as the filter structure 10 of the first embodiment, and the difference lies in the metal pattern layer 4a and the input electrode 5a of the second embodiment. The output electrode 6a. The metal pattern layer 4a is composed of a plurality of rectangular blocks 41a, 42a, 43a, 44a and a straight line segment 45a. The rectangular blocks 41a, 42a, 43a, and 44a are respectively disposed around the resonant holes 17 and electrically connected to the resonant metal layers 2 in the resonant holes 17, and the rectangular blocks 41a, 42a, 43a 44a is formed with a gap 46a between each other. The straight line segment 45a is provided on one side of the rectangular blocks 41a, 42a, 43a, 44a. One end of the input electrode 5a and the output electrode 6a is disposed on the bare space 141 of the bottom surface 14 of the base 1. The other end of the input electrode 5a and the output electrode 6a extends in the L shape on the open surface 11 and The other side of the first rectangular block 41a and the fourth rectangular block 44a are adjacent to each other and formed with a gap 47a.

Similarly, the metal pattern layer 4a of the filter structure 10, the input electrode 5a, the output electrode 6a, and the resonant metal layer 2 of the resonant holes 17 and the ground metal layer 3 are coupled to each other. The electrical characteristics of the structure 10 can be adjusted by adjusting the length of the resonant metal layer 2 and the metal pattern layer 4 to achieve a desired frequency band, and providing low insertion loss and out-band rejection. .

5a and 5b are schematic diagrams showing the measurement curves of the input reflection coefficient (S11) and the forward transmission coefficient (S21) of the filter structures of the first embodiment and the second embodiment of the present invention. As shown in the figure, since the pattern design of the metal pattern layers 4 and 4a of the filter structure 10 of the first embodiment and the second embodiment of the present invention is different, the curve 20 having the reflection coefficient (S11) at the time of measurement, Curves 30, 30a of 20a and the forward transmission coefficient (S21). Therefore, the position of the cut-off band transmission zero point 201 displayed on the curve 20 is measured on the right side in the forward transmission coefficient of the filter structure of the first embodiment. The position of the cut-off band transmission zero point 201a displayed on the curve 20a of the forward transmission coefficient of the filter structure 10 of the second embodiment is measured on the left side.

It can be seen from the above measurement that the pattern design of the metal pattern layers 4 and 4a of the filter structure 10 of the first embodiment and the second embodiment is different, and the filter structure 10 can be designed except that different frequency bands can be designed. The cut-off band transmission zero position is also different.

Please refer to FIGS. 6 and 7, which are schematic views of the filter structure of the third embodiment of the present invention and a side cross-sectional view of FIG. 6 at positions 7-7. As shown in the figure, the present embodiment is substantially the same as the first embodiment, except that the resonant holes 17 are formed by the elliptical holes 171a, 172a, and 173a having different sizes, and the aperture is small in this embodiment. The elliptical hole 173a is located between the two large-diameter elliptical holes 171a, 172a. And each of the elliptical holes 171a, 172a, 173a has a circular hole 171b, 172b, 173b adjacent to the upper edge of the inner diameter of the elliptical holes 171a, 172a, 173a. Next, the resonant metal layer 2 is provided on the inner walls of the elliptical holes 171a, 172a, and 173a and the circular holes 171b, 172b, and 173b. The resonant holes 17 are designed to communicate the circular holes 171b (172b, 173b) with the elliptical holes 171a (172a, 173a), mainly to reduce the size of the filter structure 10 to increase the Q value of the filter structure, and Suppress the spurious response. In the present drawing, the length of the elliptical hole 171a (172a, 173a) is smaller than the length of the circular hole 171b (172b, 173b), and the filter structure 10 can be adjusted by the length of the elliptical holes 171a (172a, 173a). The performance, as well as improving the frequency response of the filter structure 10.

Next, the input electrode 5 and the output electrode 6 are disposed only in the bare space 141 of the bottom surface 14. The other ends of the input electrode 5 and the output electrode 6 do not extend on the open surface 11.

It is to be noted that the straight line segment 45a of the metal pattern layer 4a of the second embodiment may be disposed on one side of the resonant holes 17, and the straight line segments 45a and the resonant metal layers in the resonant holes 17 2 Coupling capacitance and inductance are generated, so that the filter structure 10 can improve the reflection coefficient (S11) matching and the degree of out-band rejection, and achieve the required frequency band of use.

Please refer to FIG. 8, which is a schematic diagram of the appearance of a filter structure according to a fourth embodiment of the present invention. As shown in the figure, the present embodiment is substantially the same as the third embodiment, except that the metal pattern layer 4b is an inverted E shape, and the inverted E shape is disposed on one side of the resonant holes 17 and the top surface. The grounding metal layer 3 of the 13 and the two side faces 15, 16 is electrically connected. The annular portion 41b of the inverted E-shape is annularly disposed on the elliptical hole 173b having a small diameter, and is electrically connected to the grounded metal layer 3 of the bottom surface 14.

The inverted E-shaped design of the metal pattern layer 4b and the resonant metal layers 2 in the resonant holes 17 are combined to have electrical characteristics of the filter structure 10 coupled to each other, and the length of the resonant metal layer 2 can be adjusted. The metal pattern layer 4b is used to achieve the desired frequency band of use.

However, the above description is only the preferred embodiment of the present invention, and is not intended to limit the scope of the invention, and the equivalents thereof are all included in the scope of the present invention. Within the scope of protection, it is given to Chen Ming.

10‧‧‧Filter structure

1‧‧‧ base

11‧‧‧Open face

111, 112, 113, 114‧‧‧ naked space

12‧‧‧Short-circuit surface

13‧‧‧ top surface

14‧‧‧ bottom

141‧‧‧naked area

15, 16‧‧‧ side

17‧‧‧Resonance hole

171a, 172a, 173a‧‧‧ oval holes

171b, 172b, 173b‧‧‧ round holes

2‧‧‧Resonant metal layer

3‧‧‧Grounded metal layer

31‧‧‧E-shaped pattern

4, 4a, 4b‧‧‧ metal pattern layer

41a, 42a, 43a, 44a‧‧‧ rectangular blocks

41b‧‧‧Rings

45a‧‧‧ Straight line

41‧‧‧First line

42‧‧‧Second line

43‧‧‧First straight line

44‧‧‧Second straight line

441‧‧‧ spacing

45‧‧‧ third straight line

451, 46a, 47a‧‧ ‧ gap

5, 5a‧‧‧ input electrode

6, 6a‧‧‧ output electrode

20, 20a, 30, 30a‧‧‧ curves

201, 201a‧‧‧ cut-off belt transmission zero

Figure 1 is a schematic view showing the appearance of a filter structure of a first embodiment of the invention;

Figure 2 is a bottom view of Figure 1;

Figure 3 is a rear view of Figure 1;

4 is a schematic view showing the appearance of a filter structure according to a second embodiment of the present invention;

Figure 5a is a schematic diagram showing the measurement curve of the input reflection coefficient (S11) and the forward transmission coefficient (S21) of the filter structure of the first embodiment of the present invention;

Figure 5b is a schematic diagram showing the measurement curve of the input reflection coefficient (S11) and the forward transmission coefficient (S21) of the filter structure of the second embodiment of the present invention;

Figure 6 is a schematic view showing the appearance of a filter structure of a third embodiment of the present invention;

Figure 7, is a side cross-sectional view of Figure 6 at 7-7;

Figure 8 is a perspective view showing the structure of a filter according to a fourth embodiment of the present invention.

Claims (17)

A filter structure improvement comprising: a substrate having an open surface, a short circuit surface, a top surface, a bottom surface and two side surfaces, the substrate having a plurality of resonant holes, the resonant holes extending through the substrate One end of the resonant hole is located on the open surface, and the other end is located on the short circuit surface; a plurality of resonant metal layers are disposed in the resonant holes; a grounding metal layer is disposed on the short circuit surface, the top surface, The bottom metal layer and the two side surfaces; wherein the grounding metal layer disposed on the short-circuiting surface is electrically connected to the resonant metal layers of the resonant holes to form a short-circuited end, and the resonant metal layer is opened on the open surface In addition, the grounding metal layer has an E-shaped pattern on the bottom surface, and has two bare spaces on the two sides of the E-shaped pattern to expose the base, and the two bare spaces extend on the open surface. a metal pattern layer is disposed on the open surface and electrically connected to the ground metal layer; an input electrode is disposed in one of the two bare spaces; and an output electrode is disposed on the other In the bare space area; Metal pattern layer between the plurality of resonant grounding metal layer and the metal layer is composed of a filter having mutually coupled in electrical characteristics, by adjusting the resonance length of the metal layer and the metal layer is patterned to achieve the desired use frequency band. The filter structure improvement according to the first aspect of the invention, wherein the metal pattern layer is composed of a plurality of lines, and is disposed at the intersection of the open surface and the top surface, the bottom surface and the two sides, and The adjacent plurality of resonant holes are electrically connected to the grounded metal layer; wherein the plurality of lines comprise a first edge, a second edge, a first line, a second line, and a third line. The filter structure according to the second aspect of the invention, wherein the first edge is electrically connected to the ground metal surface at a junction between the open surface and the top surface and the two sides, the first The two-sided line is electrically connected to the ground metal layer by the intersection of the open surface and the bottom surface. The filter structure is improved according to the third aspect of the invention, wherein the first straight line is disposed between the two adjacent resonant holes and electrically connected to the first edge and the second edge; a second line is disposed between the two adjacent resonant holes and electrically connected to the first edge and the second edge, wherein the second line is formed with a spacing; and the third line is disposed on the two Between adjacent resonant holes and electrically connected to the first edge and the second edge, wherein a gap is formed on the third line, and the gap is located adjacent to the first edge. The filter structure is improved according to the fourth aspect of the invention, wherein one end of the input electrode is disposed on one of the two bare spaces, and the other end extends on the open surface adjacent to one of the resonant holes. . The filter structure is improved according to the fifth aspect of the invention, wherein one end of the output electrode is disposed on the other bare space region, and the other end extends on the bare space of the open surface, and adjacent to the One of these resonant holes. The filter structure improvement according to claim 1, wherein the metal pattern layer is composed of a plurality of rectangular blocks and a straight line segment, and the rectangular blocks are respectively disposed around the resonant holes on the open surface. And electrically connected to the resonant metal layers in the resonant holes, and the rectangular blocks are formed with a gap therebetween; the straight segments are disposed on one side of the rectangular blocks. The filter structure is improved according to the seventh aspect of the invention, wherein one end of the input electrode and the output electrode is disposed on a bare space of a bottom surface of the substrate, and the other end of the input electrode and the output electrode extend The open surface has an L shape adjacent to the other side of the first rectangular block and the fourth rectangular block and forms a gap. The filter structure according to claim 1, wherein the resonant holes are formed by the elliptical holes of different calibers. The filter structure according to claim 9 is characterized in that the resonant metal layer is disposed on the elliptical holes and the inner walls of the circular holes. The filter structure improvement according to claim 10, wherein the length of the elliptical hole is smaller than the length of the circular hole. The filter structure according to claim 11, wherein the metal pattern layer is an inverted E shape, and the inverted E shape is disposed on one side of the resonant holes and the ground metal of the top surface and the two side surfaces. The layer is electrically connected; wherein the annular ring portion of the inverted E-shape is disposed on the elliptical hole having a small diameter and electrically connected to the grounded metal layer of the bottom surface. A filter structure improvement comprising: a substrate having an open surface, a short circuit surface, a top surface, a bottom surface and two side surfaces, the substrate having a plurality of resonant holes, the resonant holes extending through the substrate One end of the resonant hole is located on the open surface, and the other end is located on the short circuit surface; a plurality of resonant metal layers are disposed in the resonant holes; a grounding metal layer is disposed on the short circuit surface, the top surface, The bottom metal layer and the two side surfaces; wherein the grounding metal layer disposed on the short-circuiting surface is electrically connected to the resonant metal layers of the resonant holes to form a short-circuited end, and the resonant metal layer is opened on the open surface In addition, the grounding metal layer has an E-shaped pattern on the bottom surface, and has two bare spaces on the two sides of the E-shaped pattern to expose the base, and the two bare spaces extend on the open surface. a metal pattern layer is disposed on the open surface; an input electrode is disposed in one of the two bare spaces; an output electrode is disposed in the other bare space; wherein the metal is Pattern layer and the resonant metals Composition and between the grounding metal layer structure having a filter coupled to the electrical characteristics of each other, by adjusting the length of the plurality of resonance of the metal layer and the metal layer is patterned to achieve the desired use frequency band. The filter structure according to claim 13 is characterized in that the resonant holes are formed by the elliptical holes of different calibers. The filter structure according to claim 14 is characterized in that the resonant metal layers are disposed on the elliptical holes and the inner walls of the circular holes. The filter structure according to claim 15 is characterized in that the length of the elliptical hole is smaller than the length of the circular hole. The filter structure according to claim 16 is characterized in that the metal pattern layer is a straight line segment, and the straight line segment is disposed on one side of the resonant holes.