TWI635650B - Filter structure - Google Patents

Abstract

A filter structure improvement comprises: a substrate, a plurality of resonant metal layers, a grounded metal layer, a metal pattern layer, an input electrode and an output electrode. The substrate has a plurality of resonant holes, one end of which is located on an open side of the base body and the other end is located on the short-circuited surface. The resonant metal layers are disposed in the resonant holes. The grounding metal layer is disposed on the short-circuited surface, the top surface, the bottom surface and the two side surfaces of the base body, and electrically connected to the resonant metal layers to form a short-circuited end; the input electrode and the output electrode are disposed on the bottom surface or the open surface of the base body The grounded metal layer is electrically connected. The metal pattern layer and the resonant metal layer and the ground metal layer form a mutual coupling filter electrical characteristic to adjust the length of the resonant metal layer and the metal pattern layer to achieve a desired use frequency band.

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 Short circuit end, the resonant metal layer is open Forming an open end on the surface; further, the grounding metal layer has an E-shaped pattern on the bottom surface, and has two bare spaces on the two sides of the ground metal layer of the E-shaped pattern to expose the base body. The empty area extends over the open face. 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 the plurality of lines includes a first edge, a second edge, a first line, a second line, and a third line.

In an embodiment of the invention, the first edge line is disposed at the intersection of the open surface and the top surface, the intersection of the two side surfaces with the open surface, and the intersection of the open surface and the bottom surface, and the grounding The metal surface is electrically connected to the second side line. The ground contact between the open surface and 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 the second line is a broken line and has a space thereon; and the third line is disposed at the two adjacent resonances The first line and the second line are electrically connected to each other, wherein the third line is a broken line and has a space thereon, and the interval is adjacent to the first 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 are respectively disposed on the two bare areas of the bottom surface of the substrate, and the other ends of the input electrode and the output electrode extend on the open surface. The L shape is adjacent to the first one of the rectangular block and the other side of the fourth rectangular block and forms a gap.

In an embodiment of the invention, the resonant holes are circular holes or elliptical holes of different calibers, or the elliptical holes have a circular hole therein.

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 one embodiment of the present invention, the metal pattern layer is an inverted E shape, and the inverted E-shaped metal pattern layer is electrically connected to the ground metal layer of the top surface and the two side surfaces. The inverted E-shape has an annular portion disposed on the elliptical hole having the smallest diameter, and the annular portion is 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 ground metal layer has an E-shaped pattern on the bottom surface, and has the base body on both sides of the ground metal layer of the E-shaped pattern An exposed two bare space region, the two bare spaces extending on 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 circular holes or elliptical holes of different calibers, or a circular hole is formed in the elliptical holes.

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.

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‧‧‧ interval

45‧‧‧ third straight line

451‧‧‧ interval

46a, 47a‧‧‧ gap

5, 5a‧‧‧ input electrode

6, 6a‧‧‧ output electrode

20, 20a, 30, 30a‧‧‧ curves

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

1 is a schematic view showing the structure of a filter according to a first embodiment of the invention; FIG. 2 is a bottom view of FIG. 1; FIG. 3 is a rear view of FIG. 1; and FIG. 4 is a second embodiment of the present invention. FIG. 5a is a schematic diagram of a measurement curve of an input reflection coefficient (S11) and a forward transmission coefficient (S21) of a filter structure according to a first embodiment of the present invention; FIG. 5b is a schematic diagram of the present invention. 2 is a schematic diagram of a measurement curve of an input reflection coefficient (S11) and a forward transmission coefficient (S21) of the filter structure of the second embodiment; FIG. 6 is a schematic view showing the appearance of a filter structure of a third embodiment of the present invention; Figure 6 is a side cross-sectional view of the position of Figure 7 in the 7-7 position; Figure 8 is a schematic view showing the appearance of the filter structure of the fourth embodiment of the present invention.

The technical content and detailed description of the present invention will now be described with reference to the following drawings: Referring to Figures 1-3, the appearance, bottom view and rear view of the filter structure of the first embodiment of the present invention are shown. 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. A plurality of resonant holes 17 are disposed in the base 1 , and the resonant holes 17 extend through the base 1 and the resonant holes The one end opening 17 is located on the open surface 11 and the one end opening is located on the short circuit surface 12. In the figure, the resonance hole 17 is a circular hole.

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 including 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 disposed at the intersection of the open surface 11 and the top surface 13, the intersection of the two side surfaces 15, 16 and the open surface 11, and the intersection of the open surface 11 and the bottom surface 14, and The grounded metal surface 3 is electrically connected. 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 connected to the first edge 41 and the second edge 42. The second line 44 is a dotted line on the second line 44. There is a gap 441. Further, the third line 45 is disposed between the two adjacent resonant holes 17 and electrically connected to the first edge line 41 and the second edge line 42. The third line 45 is a dotted line. There is a gap 451 on the top, and the gap 451 is located adjacent to the first edge line 41. Take The first edge line 41, the second edge line 42, the first line 43, the second line 44, and the third line 45 of the metal pattern layer 4 surround the open surface 11 with a plurality of bare areas 111. And 112, 113, 114, and the resonant metal layer 2 of the resonant hole 17 and the ground metal layer 3 are formed 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 and 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. The input power The pole 5a and one end of the output electrode 6a are 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 extend in the L shape on the open surface 11 and the first The rectangular block 41a and the other side of the fourth rectangular block 44a are adjacent to each other and are 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: this embodiment is substantially the same as the first embodiment, The difference is that the resonant holes 17 are formed by the elliptical holes 171a, 172a, and 173a having different caliber sizes. In the embodiment, the elliptical holes 173a having small calibers are located in the two large-diameter elliptical holes 171a and 172a. between. 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, this 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-shaped metal pattern layer 4b is disposed around the resonant holes 17 The side is electrically connected to the ground metal layer 3 of the top surface 13 and the two side surfaces 15 and 16. Wherein the inverted E shape has An annular portion 41b is disposed on the elliptical hole having the smallest diameter, and the annular portion 41b 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.

Claims (4)

A filter structure improvement includes: a base body having 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, 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 grounded 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 ground metal layer has an E-shaped pattern on the bottom surface, and has two bare spaces on the two sides of the ground metal layer of the E-shaped pattern, and the two bare spaces extend to a metal pattern layer is disposed on the open surface and electrically connected to the ground metal layer, the metal pattern layer is composed of a plurality of lines, the plurality of lines including a first edge, and a Second side, one a straight line, a second straight line and a third straight line, the first edge line is disposed at the intersection of the open surface and the top surface, the intersection of the two side surfaces with the open surface, and the intersection of the open surface and the bottom surface And electrically connected to the grounded metal surface, the second edge is electrically connected to the ground metal layer at an intersection of the open surface and the bottom surface, and the first straight line is disposed between the two adjacent resonant holes And electrically connected to the first edge and the second edge; the 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 a broken line and has a space thereon; further, the third line is disposed between the two adjacent resonant holes and the first edge and the The second side line is electrically connected, wherein the third line is a broken line, and has a space thereon, the interval is adjacent to the first edge line; an input electrode, the upper end of which is disposed in the second bare space region The other end extends on the open surface adjacent to one of the resonant holes; an output electrode having an upper end attached to the other bare space and the other end extending to the bare space of the open surface And adjacent to the one of the resonant holes; wherein the metal pattern layer and the resonant metal layer and the ground metal layer form electrical characteristics of the filter structure having mutual coupling, and the resonant metal layer can be adjusted The length and the metal pattern layer are used to achieve the desired frequency band of use. A filter structure improvement includes: a base body having 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, 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, and 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 ground metal layer has an E-shaped pattern on the bottom surface, and has two bare spaces on the two sides of the ground metal layer of the E-shaped pattern, and the two bare spaces extend to The open side; a metal pattern layer is disposed on the open surface and electrically connected to the ground metal layer. The metal pattern layer is composed of a plurality of rectangular blocks and a straight line segment, and the rectangular blocks are respectively disposed on the open surface. The resonant holes are electrically connected to the resonant metal layers of 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 An input electrode is disposed in one of the two bare regions; an output electrode is disposed in the other bare space; wherein the input electrode and one end of the output electrode are respectively disposed on a bottom surface of the substrate The other end of the input electrode and the output electrode extend in an L shape on the open surface adjacent to the other side of the first rectangular block and the fourth rectangular block and form a a gap, wherein the metal pattern layer and the resonant metal layer and the ground metal layer form electrical characteristics of a filter structure having mutual coupling, and the length of the resonant metal layer and the metal pattern layer can be adjusted to achieve a desired use. Frequency band. A filter structure improvement includes: a base body having 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, One end of the resonant hole is located on the open surface, and the other end is located on the short circuit surface, wherein the resonant holes have a circular hole in the elliptical hole, the length of the elliptical hole is smaller than the length of the circular hole; a plurality of resonant metal layers, And being disposed on the inner wall of the elliptical hole and the circular hole; a grounding metal layer is disposed on the short circuit surface, the top surface, the bottom surface and the two side surfaces; wherein the short circuit surface is disposed The grounding metal layer is electrically connected to the resonant metal layers of the resonant holes to form a short-circuited end, and the resonant metal layer forms an open end on the open surface; In addition, the ground metal layer has an E-shaped pattern on the bottom surface, and has two bare spaces on the two sides of the ground metal layer of the E-shaped pattern, and the two bare spaces extend to the opening. a metal pattern layer is disposed on the open surface and electrically connected to the ground metal layer, wherein the metal pattern layer is an inverted E shape, and the inverted E-shaped metal pattern layer surrounds the resonance layer The side of the hole is electrically connected to the grounding metal layer of the top surface and the two side surfaces; wherein the inverted E shape has an annular portion disposed on the elliptical hole having the smallest diameter, and the annular portion and the grounding metal of the bottom surface An electrical connection; an input electrode is disposed in one of the two bare regions; an output electrode is disposed in the other bare region; wherein the metal pattern layer and the resonant metal layer The ground metal layers are formed with electrical characteristics of the filter structure coupled to each other, and the length of the resonant metal layer and the metal pattern layer can be adjusted to achieve a desired frequency band of use. A filter structure improvement includes: a base body having 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, One end of the resonant hole is located on the open surface, and the other end is located on the short circuit surface, wherein the resonant holes have a circular hole in the elliptical hole, the length of the elliptical hole is smaller than the length of the circular hole; a plurality of resonant metal layers, And being disposed on the inner wall of the elliptical hole and the circular hole; a grounding metal layer is disposed on the short circuit surface, the top surface, the bottom surface and the two side surfaces; wherein the short circuit surface is disposed on the short circuit surface Ground metal layer and the resonant metals in the resonant holes The layer is electrically connected to form a short-circuited end, and the resonant metal layer forms an open end on the open surface; and the grounded metal layer is in an E-shaped pattern on the bottom surface, and two of the grounded metal layers in the E-shaped pattern The side has a second bare space exposed to the outside of the substrate, the two bare areas extending on the open surface; a metal pattern layer is disposed on the open surface, the metal pattern layer is a straight line segment, and the straight line segment is disposed on the side One of the resonant holes; an input electrode is disposed in one of the two bare regions; an output electrode is disposed in the other bare region; wherein the metal pattern layer and the resonance The metal layer and the grounded metal layer are formed with electrical characteristics of the filter structure coupled to each other, and the length of the resonant metal layer and the metal pattern layer can be adjusted to achieve a desired use frequency band.