Band-pass filter

Abstract

A bandpass filter includes a main body, two input / output posts, multiple resonant posts, and a conductive cage. The input / output posts are located on opposite sides of the main body in one direction. Multiple resonant posts are disposed within the main body. Each resonant post has a first end and a second end. The multiple resonant posts include two input / output resonant posts and at least one intermediate resonant post. The input / output resonant posts are adjacent to and electrically connected to the input / output posts. The intermediate resonant post is located between the input / output resonant posts in the aforementioned direction. The conductive cage surrounds the resonant posts and includes a bottom layer, a top layer, and multiple side connectors. The side connectors connect the bottom layer and the top layer. The first end of each resonant post is connected to the bottom layer. The second end of each resonant post is spaced apart from the top layer. The minimum distance between each resonant post and the side connector is less than the minimum distance between the resonant posts.

Description

Technical Field

[0001] This invention relates to a filter, and more particularly to a bandpass filter. Prior Technology

[0002] Among the various passive components in electronic devices, filters can filter signals at certain frequencies. This allows noise to be filtered out. Furthermore, bandpass filters can allow signals of specific frequencies and bandwidths to pass through.

[0003] Modern electronic devices typically require miniaturization. Therefore, bandpass filters also require miniaturization. Summary of the Invention

[0004] In view of the above problems, one objective of the present invention is to provide a bandpass filter that meets the requirements of miniaturization.

[0005] One embodiment of the present invention provides a bandpass filter comprising a main body, two input / output posts, multiple resonant posts, and a conductive cage. The input / output posts are located on opposite sides of the main body in one direction. Multiple resonant posts are disposed within the main body. Each resonant post has a first end and a second end. The multiple resonant posts include two input / output resonant posts and at least one intermediate resonant post. The input / output resonant posts are adjacent to and electrically connected to the input / output posts, respectively. The intermediate resonant post is located between the two input / output resonant posts in the aforementioned direction. The conductive cage surrounds the resonant posts. The conductive cage includes a bottom layer, a top layer, and multiple side connectors. The side connectors connect the bottom layer and the top layer. The first end of each resonant post is connected to the bottom layer. The second end of each resonant post is spaced apart from the top layer. The minimum distance between each resonant post and one of the side connectors is less than the minimum distance between the resonant posts.

[0006] According to one embodiment of the present invention, a bandpass filter is formed by connecting the first end of a resonant pillar to the bottom layer and setting the second end to be spaced apart from the top layer. This allows the resonant pillar itself to form an inductor (L), and a capacitor (C) to be formed between the resonant pillar and the top layer, thus forming an inductor-capacitor (LC) type filter in a limited space. This allows the bandpass filter to meet the requirements of miniaturization.

[0007] The above description of the content of this invention and the following description of its embodiments are intended to demonstrate and explain the spirit and principles of this invention, and to provide a further explanation of the scope of this patent application. Simple Explanation of the Diagram

[0008] Figure 1 illustrates a perspective view of a bandpass filter according to one embodiment of the present invention.

[0009] Figure 2 shows a top view of the bandpass filter in Figure 1.

[0010] Figure 3 shows a schematic diagram of the right-side side view of the bandpass filter in Figure 1.

[0011] Figure 4 shows the equivalent circuit diagram of the bandpass filter in Figure 1.

[0012] Figure 5 illustrates the insertion loss and reflection loss of the bandpass filter in Figure 1 relative to frequency.

[0013] Figure 6 illustrates a perspective view of a bandpass filter according to another embodiment of the present invention.

[0014] Figure 7 shows a top view of the bandpass filter in Figure 6.

[0015] Figure 8 shows a schematic diagram of the right-side side view of the bandpass filter in Figure 6.

[0016] Figure 9 shows the equivalent circuit diagram of the bandpass filter in Figure 6.

[0017] Figure 10 illustrates the insertion loss and reflection loss of the bandpass filter in Figure 6 relative to frequency.

[0018] Figure 11 illustrates a perspective view of a bandpass filter according to another embodiment of the present invention.

[0019] Figure 12 shows a top view of the bandpass filter in Figure 11.

[0020] Figure 13 shows a front view cross section along line AA in Figure 12.

[0021] Figure 14 shows the equivalent circuit diagram of the bandpass filter in Figure 11.

[0022] Figure 15 illustrates the insertion loss and reflection loss of the bandpass filter in Figure 11 relative to frequency.

[0023] Figure 16 illustrates a perspective view of a bandpass filter according to another embodiment of the present invention.

[0024] Figure 17 shows a top view of the bandpass filter in Figure 16.

[0025] Figure 18 shows a schematic left-side view of the bandpass filter in Figure 16.

[0026] Figure 19 shows the equivalent circuit diagram of the bandpass filter in Figure 16.

[0027] Figure 20 illustrates the insertion loss and reflection loss of the bandpass filter in Figure 16 relative to frequency.

[0028] Figure 21 illustrates a perspective view of a bandpass filter according to another embodiment of the present invention.

[0029] Figure 22 shows a top view of the bandpass filter in Figure 21.

[0030] Figure 23 shows a schematic left-side view of the bandpass filter in Figure 21.

[0031] Figure 24 shows the equivalent circuit diagram of the bandpass filter in Figure 21.

[0032] Figure 25 illustrates the insertion loss and reflection loss of the bandpass filter in Figure 21 relative to frequency. Implementation

[0033] The following embodiments describe in detail the features and advantages of the present invention, the content of which is sufficient to enable anyone skilled in the art to understand the technical content of the embodiments of the present invention and to implement them accordingly. Based on the disclosure, claims, and drawings in this specification, anyone skilled in the art can easily understand the relevant objectives and advantages of the present invention. The following embodiments further illustrate the content of the present invention, but are not intended to limit the scope of the present invention in any way.

[0034] In the schematic diagrams described herein, dimensions, proportions, and angles may be exaggerated for illustrative purposes, but are not intended to limit the invention. Various modifications are possible without departing from the spirit of the invention. The up, down, front, and back orientations mentioned in the descriptions of the embodiments and drawings are for illustrative purposes and are not intended to limit the invention.

[0035] Please refer to Figures 1 through 5. Figure 1 shows a perspective view of a bandpass filter according to one embodiment of the present invention. Figure 2 shows a top view of the bandpass filter of Figure 1. Figure 3 shows a right side view of the bandpass filter of Figure 1. Figure 4 shows an equivalent circuit diagram of the bandpass filter of Figure 1. Figure 5 shows a schematic diagram of the insertion loss and reflection loss of the bandpass filter of Figure 1 relative to frequency.

[0036] As shown in Figures 1 to 3, the bandpass filter 1 includes a main body 11, two input / output pillars 121 and 122, multiple resonant pillars 13, two electrical connectors 141 and 142, a conductive cage 15, and multiple capacitor conductors 161, 162, and 163.

[0037] Input / output posts 121 and 122 are located on opposite sides of the main body 11 in the X direction. Resonant posts 13 are disposed within the main body 11. Each resonant post 13 has a first end 13a and a second end 13b. The resonant posts 13 include two input / output resonant posts 131 and 132 and multiple intermediate resonant posts 133. Input / output resonant posts 131 are adjacent to input / output posts 121. Input / output resonant posts 131 are electrically connected to input / output posts 121 via electrical connectors 141. Input / output resonant posts 132 are adjacent to input / output posts 122. Input / output resonant posts 132 are electrically connected to input / output posts 122 via electrical connectors 142. The main body 11 is made of an insulating or dielectric material. Input / output posts 121, 122, and resonant posts 13 are made of a conductive material.

[0038] The resonant pillar 13 is located between the input / output pillars 121 and 122 in the X direction. Specifically, the input / output pillar 121 is located on the positive X side of the resonant pillar 13, and the input / output pillar 122 is located on the negative X side of the resonant pillar 13. Furthermore, a plurality of intermediate resonant pillars 133 are located between the input / output resonant pillars 131 and 132 in the X direction. Specifically, the input / output resonant pillar 131 is located on the positive X side of the intermediate resonant pillars 133, and the input / output resonant pillar 132 is located on the negative X side of the intermediate resonant pillars 133.

[0039] A conductive cage 15 surrounds a resonant pillar 13 with its axis in the X direction. The conductive cage 15 includes a bottom layer 151, a top layer 152, and multiple side connectors 153 and 154. The two ends of the side connectors 153 and 154 are connected to the bottom layer 151 and the top layer 152, respectively. The resonant pillar 13 is located between the bottom layer 151 and the top layer 152 in the Z direction. Specifically, the bottom layer 151 is located on the negative Z side of the resonant pillar 13, and the top layer 152 is located on the positive Z side of the resonant pillar 13. The resonant pillar 13 is located between two groups of side connectors 153 and 154 in the Y direction. Specifically, the multiple side connectors 153 are arranged approximately along the X direction and located on the positive Y side of the resonant pillar 13. The multiple side connectors 154 are arranged approximately along the X direction and located on the negative Y side of the resonant pillar 13.

[0040] As shown in Figures 2 and 3, the first end 13a of the resonant pillar 13 is connected to the bottom layer 151. The second end 13b of the resonant pillar 13 is spaced apart from the top layer 152. The conductive cage 15 is grounded. The input / output pillars 121 and 122 are closer to the bottom layer 151 and farther from the top layer 152. The height H1 of one of the input / output pillars 121 and 122 is one-quarter to one-half of the height H2 of one of the input / output resonant pillars 131 and 132. Electrical connectors 141 and 142 are located between the first end 13a and the second end 13b of the resonant pillar 13. Capacitor conductors 161, 162, and 163 are disposed within the main body 11 and are respectively connected to the second end 13b of the resonant pillar 13. Specifically, capacitor conductor 161 is connected to the second end 13b of the input / output resonant pillar 131. Capacitor conductor 162 is connected to the second end 13b of the input / output resonant pillar 132. Capacitor conductor 163 is connected to the second end 13b of the intermediate resonant pillar 133. Capacitor conductors 161, 162, and 163 are arranged to be spaced apart from the top layer 152, thereby forming a capacitor.

[0041] Each resonant post 13 has a minimum distance D1, D2, or D3 between itself and the side connector 153. Specifically, the input / output resonant post 131 has a minimum distance D1 between itself and the side connector 153, the input / output resonant post 132 has a minimum distance D2 between itself and the side connector 153, and the intermediate resonant post 133 has a minimum distance D3 between itself and the side connector 153. The resonant posts 13 have a minimum distance D4 or D5 between themselves. Specifically, the input / output resonant post 131 has a minimum distance D4 between itself and the nearest intermediate resonant post 133, and the input / output resonant post 132 has a minimum distance D5 between itself and the nearest intermediate resonant post 133. The minimum distance D1 between the input / output resonant post 131 and the side connector 153 is less than the minimum distances D4 and D5 between the input / output resonant posts 131 and 132 and the nearest intermediate resonant post 133. The minimum distance D2 between the input / output resonant pillar 132 and the side connector 153 is less than the minimum distances D4 and D5 between the input / output resonant pillars 131 and 132 and the nearest intermediate resonant pillar 133. The minimum distance D3 between the intermediate resonant pillar 133 and the side connector 153 is less than the minimum distances D4 and D5 between the input / output resonant pillars 131 and 132 and the nearest intermediate resonant pillar 133.

[0042] Two adjacent intermediate resonant pillars 133 have a minimum distance D6 between them. The minimum distance D4 between the input / output resonant pillar 131 and the nearest intermediate resonant pillar 133 is less than the minimum distance D6 between the intermediate resonant pillars 133. The minimum distance D5 between the input / output resonant pillar 132 and the nearest intermediate resonant pillar 133 is less than the minimum distance D6 between the intermediate resonant pillars 133.

[0043] The distance D7 between input / output resonant pillar 131 and input / output resonant pillar 132 is greater than the distances D4, D5, and D6 between the other two adjacent resonant pillars. Specifically, distance D7 is greater than the minimum distance D4 between input / output resonant pillar 131 and intermediate resonant pillar 133. Distance D7 is greater than the minimum distance D5 between input / output resonant pillar 132 and intermediate resonant pillar 133. Distance D7 is greater than the minimum distance D6 between intermediate resonant pillars 133.

[0044] The angle θ1 between the line L1 connecting the center of the input / output resonant pillar 131 to the center of the nearest input / output pillar 121 and the line L2 connecting the center of the input / output resonant pillar 131 to the center of the nearest intermediate resonant pillar 133 is less than 90 degrees. The angle θ2 between the line L3 connecting the center of the input / output resonant pillar 132 to the center of the nearest input / output pillar 122 and the line L4 connecting the center of the input / output resonant pillar 132 to the center of the nearest intermediate resonant pillar 133 is less than 90 degrees. The bandpass filter 1 can be formed by connecting the first end 13a of the resonant pillar 13 to the bottom layer 151 and setting the second end 13b to be spaced from the top layer 152, so that the resonant pillar 13 itself forms an inductor (L), and the resonant pillar 13 and the top layer 152 form a capacitor (C), thus forming an inductor-capacitor (LC) filter in a very small horizontal area and a limited height (i.e., a limited space). In this way, the bandpass filter 1 meets the requirements of miniaturization.

[0045] In this embodiment, the resonant pillars 13 are arranged in a trapezoidal shape, but this is not a limitation. In other embodiments, the resonant pillars 13 can be arranged in a zigzag pattern or in other polygonal arrangements. This reduces the required distance of the resonant pillars 13 in the X direction.

[0046] In this embodiment, the main body 11 is made of ceramic. For example, the main body 11 may be a low-temperature co-fired ceramic (LTCC). This allows the main body 11 to fill the space between the resonant pillar 13 and the conductive cage 15. However, this is not a limitation. In other embodiments, the main body 11 may also be other insulating or dielectric materials capable of filling the space between the resonant pillar 13 and the conductive cage 15.

[0047] In this embodiment, the side connector 153 is a plurality of connecting posts, but is not limited thereto. In other embodiments, the side connector 153 may also be two side conductive layers, located on the positive Y side and the negative Y side of the resonant post 13, respectively.

[0048] In this embodiment, the bandpass filter 1 is symmetrical about the YZ plane. Input / output posts 121 and 122 can select one input signal and the other output signal, but are not limited thereto. In other embodiments, the bandpass filter may also be asymmetrical.

[0049] Figures 4 and 5 illustrate the bandpass effect of bandpass filter 1. In Figure 4, capacitor C1 is formed by capacitor conductor 161 and top layer 152, capacitor conductor 162 and top layer 152, and capacitor conductor 163 and top layer 152, respectively (Figure 3). In one example, the length of bandpass filter 1 in the X direction (approximately the distance from input / output post 121 to input / output post 122) is approximately 2.0 mm, its length in the Y direction (approximately the distance from side connector 153 to side connector 154) is approximately 1.2 mm, and its length in the Z direction (approximately the distance from bottom layer 151 to top layer 152) is approximately 0.8 mm. In Figure 5, the TL line represents a schematic diagram of insertion loss relative to frequency, and the RL line represents a schematic diagram of reflection loss relative to frequency. A signal of a certain frequency is input from input / output post 121, and the intensity of the signal that can penetrate bandpass filter 1 and reach input / output post 122 is recorded. By scanning input signals of different frequencies, the TL line is plotted. A signal of a certain frequency is input through input / output post 121. The intensity of the signal reflected by bandpass filter 1 received by input / output post 121 is recorded. By scanning input signals of different frequencies, the RL line is drawn.

[0050] As shown in Figure 5, signals with frequencies below approximately 22.50 GHz are almost entirely reflected by bandpass filter 1 and cannot penetrate it. Signals with frequencies between approximately 22.50 and 24.50 GHz partially penetrate bandpass filter 1 and are partially reflected by it. Signals with frequencies between approximately 24.50 and 27.50 GHz mostly penetrate bandpass filter 1. The bandwidth of bandpass filter 1 is approximately 3.00 GHz, and its center frequency is approximately 26.00 GHz. Signals with frequencies between approximately 27.50 and 28.50 GHz partially penetrate bandpass filter 1 and are partially reflected by it. Signals with frequencies above approximately 28.50 GHz are almost entirely reflected by bandpass filter 1 and cannot penetrate it. In the RL line, four points P are visible where the signal reflection loss drops sharply. This number corresponds to the number of resonant pillars 13 (one input-output resonant pillar 131, two intermediate resonant pillars 133, and one input-output resonant pillar 132). Based on this, it can be inferred that the more resonant pillars 13 there are, the wider the bandwidth of the bandpass filter 1 may be.

[0051] In this embodiment, there are two intermediate resonant pillars 133, but this is not a limitation. In other embodiments, there may be only one intermediate resonant pillar 133, which may narrow the bandwidth of the bandpass filter 1. The designer of the bandpass filter 1 can design bandpass filters with different bandwidths and center frequencies as needed.

[0052] Please refer to Figures 6 through 10. Figure 6 shows a perspective view of a bandpass filter according to another embodiment of the present invention. Figure 7 shows a top view of the bandpass filter of Figure 6. Figure 8 shows a right side view of the bandpass filter of Figure 6. Figure 9 shows an equivalent circuit diagram of the bandpass filter of Figure 6. Figure 10 shows a schematic diagram of the insertion loss and reflection loss of the bandpass filter of Figure 6 relative to frequency.

[0053] As shown in Figures 6 to 8, the bandpass filter 2 is similar to the bandpass filter 1 shown in Figures 1 to 3. The bandpass filter 2 includes a main body 21, two input and output pillars 221 and 222, multiple resonant pillars 23, two electrical connectors 241 and 242, a conductive cage 25, and multiple capacitor conductors 261, 262, and 263.

[0054] Input / output posts 221 and 222 are located on opposite sides of the main body 21 in the X direction. Resonant posts 23 are disposed within the main body 21. Each resonant post 23 has a first end 23a and a second end 23b. Each resonant post 23 includes two input / output resonant posts 231 and 232 and multiple intermediate resonant posts 233. Input / output resonant posts 231 are electrically connected to input / output posts 221 via electrical connectors 241. Input / output resonant posts 232 are electrically connected to input / output posts 222 via electrical connectors 242. Resonant posts 23 are located between input / output posts 221 and 222 in the X direction. A conductive cage 25 surrounds the resonant posts 23 with the X direction as its axis. The conductive cage 25 includes a bottom layer 251, a top layer 252, and multiple side connectors 253 and 254. The two ends of the side connectors 253 and 254 are respectively connected to the bottom layer 251 and the top layer 252. The resonant column 23 is located between the bottom layer 251 and the top layer 252, and between the side connector 253 and the side connector 254.

[0055] As shown in Figures 7 and 8, the first end 23a of the resonant pillar 23 is connected to the bottom layer 251. The second end 23b of the resonant pillar 23 is spaced apart from the top layer 252. The conductive cage 25 is grounded. Capacitor conductors 261, 262, and 263 are disposed within the main body 21 and are respectively connected to the second end 23b of the resonant pillar 23. The capacitor conductors 261, 262, and 263 are spaced apart from the top layer 252, thereby forming a capacitor. The minimum distance D1 between the input / output resonant pillar 231 and the side connector 253, the minimum distance D2 between the input / output resonant pillar 232 and the side connector 253, and the minimum distance D3 between the intermediate resonant pillar 233 and the side connector 253 are all smaller than the minimum distances D4 and D5 between the resonant pillars 23.

[0056] The bandpass filter 2 in this embodiment further has the following features: Among the capacitor conductors 261, 262, and 263, the distance D21 between capacitor conductor 261 connected to the input / output resonant pillar 231 and capacitor conductor 262 connected to the input / output resonant pillar 232 is less than the minimum distances D4 and D5 between the resonant pillars 23. Furthermore, distance D21 is also less than the distance D22 between capacitor conductor 261 connected to the input / output resonant pillar 231 and capacitor conductor 263 connected to the intermediate resonant pillar 233. Distance D21 is also less than the distance D23 between capacitor conductor 262 connected to the input / output resonant pillar 232 and capacitor conductor 263 connected to the intermediate resonant pillar 233. Distance D21 is also less than the distance D24 between capacitor conductors 263 connected to the intermediate resonant pillar 233. Therefore, a capacitor can be formed between capacitor conductors 261 and 262. Since the distance D22 between capacitor conductors 261 and 263 is greater than the distance D21, a capacitor is not formed between them. Because the distance between capacitor conductors 262 and 263 is greater than the distance between them and D21, no capacitance is formed. Similarly, because the distance between multiple capacitor conductors 263 and D24 is greater than the distance between them and D21, no capacitance is formed.

[0057] Figures 9 and 10 illustrate the bandpass effect of bandpass filter 2. In Figure 9, capacitor C1 is formed by capacitor conductor 261 and top layer 252, capacitor conductor 262 and top layer 252, and capacitor conductor 263 and top layer 252 respectively (Figure 8), and capacitor C2 is formed by capacitor conductor 261 and capacitor conductor 262 (Figure 7).

[0058] In Figure 10, the TL line represents the insertion loss relative to frequency, and the RL line represents the reflection loss relative to frequency. As shown in Figure 10, signals with frequencies below approximately 24.0 GHz are almost entirely reflected by bandpass filter 2 and cannot penetrate it. Signals with frequencies between approximately 24.0 and 26.0 GHz partially penetrate bandpass filter 2 and are partially reflected by it. Signals with frequencies between approximately 26.0 and 29.0 GHz mostly penetrate bandpass filter 2. The bandwidth of bandpass filter 2 is approximately 3.00 GHz, and its center frequency is approximately 27.5 GHz. Signals with frequencies between approximately 29.0 and 29.50 GHz partially penetrate bandpass filter 2 and are partially reflected by it. Signals with frequencies above approximately 29.50 GHz are almost entirely reflected by bandpass filter 2 and cannot penetrate it. As can be seen, the bandwidth of the higher-frequency band (29.0~29.50 GHz) where "the signal partially penetrates bandpass filter 2 and is partially reflected by bandpass filter 2" is approximately 0.5 GHz. In contrast, the bandwidth of the higher-frequency band (29.0~29.50 GHz) where "the signal partially penetrates bandpass filter 1 and is partially reflected by bandpass filter 1" is approximately 1.00 GHz. Therefore, in this embodiment, bandpass filter 2 has a narrowed bandwidth where "the signal partially penetrates bandpass filter 2 and is partially reflected by bandpass filter 2," a situation where "the bandwidth where it is difficult to distinguish whether the signal penetrates or not" is narrowed.

[0059] Please refer to Figures 11 through 15. Figure 11 shows a perspective view of a bandpass filter according to another embodiment of the present invention. Figure 12 shows a top view of the bandpass filter of Figure 11. Figure 13 shows a front cross-sectional view along line AA of Figure 12. Figure 14 shows an equivalent circuit diagram of the bandpass filter of Figure 11. Figure 15 shows a schematic diagram of the insertion loss and reflection loss of the bandpass filter of Figure 11 relative to frequency.

[0060] As shown in Figures 11 to 13, the bandpass filter 3 is similar to the bandpass filter 1 shown in Figures 1 to 3. The bandpass filter 3 includes a main body 31, two input and output pillars 321 and 322, multiple resonant pillars 33, two electrical connectors 341 and 342, a conductive cage 35, and multiple capacitor conductors 361, 362, and 363.

[0061] Input / output posts 321 and 322 are located on opposite sides of the main body 31 in the X direction. Resonant posts 33 are disposed within the main body 31. Each resonant post 33 has a first end 33a and a second end 33b. The resonant posts 33 include two input / output resonant posts 331 and 332 and multiple intermediate resonant posts 333. Input / output resonant posts 331 are electrically connected to input / output posts 321 via electrical connectors 341. Input / output resonant posts 332 are electrically connected to input / output posts 322 via electrical connectors 342. The resonant posts 33 are located between input / output posts 321 and 322 in the X direction. A conductive cage 35 surrounds the resonant posts 33 with the X direction as its axis. The conductive cage 35 includes a bottom layer 351, a top layer 352, and multiple side connectors 353 and 354. The two ends of the side connectors 353 and 354 are respectively connected to the bottom layer 351 and the top layer 352. The resonant column 33 is located between the bottom layer 351 and the top layer 352, and between the side connector 353 and the side connector 354.

[0062] As shown in Figures 12 and 13, the first end 33a of the resonant pillar 33 is connected to the bottom layer 351. The second end 33b of the resonant pillar 33 is spaced apart from the top layer 352. The conductive cage 35 is grounded. Capacitor conductors 361, 362, and 363 are disposed within the main body 31 and are respectively connected to the second end 33b of the resonant pillar 33. The capacitor conductors 361, 362, and 363 are spaced apart from the top layer 352, thereby forming a capacitor. The minimum distance D1 between the input / output resonant pillar 331 and the side connector 353, the minimum distance D2 between the input / output resonant pillar 332 and the side connector 353, and the minimum distance D3 between the intermediate resonant pillar 333 and the side connector 353 are all smaller than the minimum distances D4 and D5 between the resonant pillars 33.

[0063] The bandpass filter 3 in this embodiment further has the following features: The bandpass filter 3 further includes a floating conductor 37. Capacitor conductors 363 connected to the intermediate resonant pillar 333 are adjacent to each other. The floating conductor 37 is arranged to overlap with two adjacent capacitor conductors 363 and spaced apart from each other. The floating conductor 37 is disposed between the first end 33a and the second end 33b of the resonant pillar 33. The floating conductor 37 is disposed closer to the second end 33b and farther from the first end 33a. The floating conductor 37 is electrically floating without being electrically connected to any component. Thereby, the capacitor conductors 363, the floating conductor 37, and the capacitor conductors 363 can form a capacitor.

[0064] Figures 14 and 15 illustrate the bandpass effect of bandpass filter 3. In Figure 14, capacitor C1 is formed by capacitor conductor 361 and top layer 352, capacitor conductor 362 and top layer 352, and capacitor conductor 363 and top layer 352 respectively (Figure 13). Capacitor C3 is formed by capacitor conductor 363, floating conductor 37, and capacitor conductor 363 (Figure 13).

[0065] In Figure 15, the TL line represents the insertion loss relative to frequency, and the RL line represents the reflection loss relative to frequency. As shown in Figure 15, signals with frequencies below approximately 25.75 GHz are almost entirely reflected by bandpass filter 3 and cannot penetrate it. Signals with frequencies between approximately 25.75 and 26.25 GHz partially penetrate bandpass filter 3 and are partially reflected by it. Signals with frequencies between approximately 26.25 and 29.75 GHz mostly penetrate bandpass filter 3. The bandwidth of bandpass filter 3 is approximately 3.50 GHz, and its center frequency falls around 28.00 GHz. Signals with frequencies between approximately 29.75 and 31.25 GHz partially penetrate bandpass filter 3 and are partially reflected by it. Signals with frequencies above approximately 31.25 GHz are almost entirely reflected by bandpass filter 3 and cannot penetrate it. As can be seen, the bandwidth of the lower frequency band (25.75~26.25 GHz) where "the signal partially penetrates the bandpass filter 3 and is partially reflected by the bandpass filter 3" is approximately 0.5 GHz. In contrast, the bandwidth of the higher frequency band (25.75~26.25 GHz) where "the signal partially penetrates the bandpass filter 1 and is partially reflected by the bandpass filter 1" is approximately 1.00 GHz. Therefore, in this embodiment, the bandpass filter 3 has a narrowed bandwidth where "the signal partially penetrates the bandpass filter 3 and is partially reflected by the bandpass filter 3," a situation where "the bandwidth where it is difficult to distinguish whether the signal penetrates or not" is narrowed.

[0066] Please refer to Figures 16 to 20. Figure 16 shows a perspective view of a bandpass filter according to another embodiment of the present invention. Figure 17 shows a top view of the bandpass filter of Figure 16. Figure 18 shows a left side view of the bandpass filter of Figure 16. Figure 19 shows an equivalent circuit diagram of the bandpass filter of Figure 16. Figure 20 shows a schematic diagram of the insertion loss and reflection loss of the bandpass filter of Figure 16 relative to frequency.

[0067] As shown in Figures 16 to 18, the bandpass filter 4 is similar to the bandpass filter 1 shown in Figures 1 to 3. The bandpass filter 4 includes a main body 41, two input / output pillars 421 and 422, multiple resonant pillars 43, two electrical connectors 441 and 442, a conductive cage 45, and multiple capacitor conductors 461, 462, and 463.

[0068] Input / output posts 421 and 422 are located on opposite sides of the main body 41 in the X direction. Resonant posts 43 are disposed within the main body 41. Each resonant post 43 has a first end 43a and a second end 43b. The resonant posts 43 include two input / output resonant posts 431 and 432 and multiple intermediate resonant posts 433. Input / output resonant posts 431 are electrically connected to input / output posts 421 via electrical connectors 441. Input / output resonant posts 432 are electrically connected to input / output posts 422 via electrical connectors 442. The resonant posts 43 are located between input / output posts 421 and 422 in the X direction. A conductive cage 45 surrounds the resonant posts 43 with the X direction as its axis. The conductive cage 45 includes a bottom layer 451, a top layer 452, and multiple side connectors 453 and 454. The two ends of the side connectors 453 and 454 are respectively connected to the bottom layer 451 and the top layer 452. The resonant pillar 43 is located between the bottom layer 451 and the top layer 452, and between the side connector 453 and the side connector 454. In this embodiment, the resonant pillar 43 is arranged in a sawtooth pattern.

[0069] As shown in Figures 17 and 18, the first end 43a of the resonant pillar 43 is connected to the bottom layer 451. The second end 43b of the resonant pillar 43 is spaced apart from the top layer 452. The conductive cage 45 is grounded. Capacitor conductors 461, 462, and 463 are disposed within the main body 41 and are respectively connected to the second end 43b of the resonant pillar 43. The capacitor conductors 461, 462, and 463 are spaced apart from the top layer 452, thereby forming a capacitor. The minimum distance D1 between the input / output resonant pillar 431 and the side connector 453, the minimum distance D2 between the input / output resonant pillar 432 and the side connector 453, and the minimum distances D3 and D33 between the intermediate resonant pillar 433 and the side connector 453 are all smaller than the minimum distances D4 and D5 between the resonant pillars 43.

[0070] The bandpass filter 4 in this embodiment further has the following features. The bandpass filter 4 further includes two floating conductors 481 and 482. A capacitor conductor 461 connected to the input / output resonant pillar 431 and one of the capacitor conductors 463 connected to the intermediate resonant pillar 433 are adjacent to each other. The floating conductor 481 is arranged to overlap with and be spaced apart from the capacitor conductor 461 and the nearest capacitor conductor 463. A capacitor conductor 462 connected to the input / output resonant pillar 432 and one of the capacitor conductors 463 connected to the intermediate resonant pillar 433 are adjacent to each other. The floating conductor 482 is arranged to overlap with and be spaced apart from the capacitor conductor 462 and the nearest capacitor conductor 463. The floating conductors 481 and 482 are located between the first end 43a and the second end 43b of the resonant pillar 43. The floating conductors 481 and 482 are located closer to the second end 43b and farther from the first end 43a. The floating conductors 481 and 482 are electrically floating without being electrically connected to any component. Thus, capacitor conductor 461, floating conductor 481, and nearest capacitor conductor 463 can form a capacitor. Capacitor conductor 462, floating conductor 482, and nearest capacitor conductor 463 can also form a capacitor.

[0071] Figures 19 and 20 illustrate the bandpass effect of bandpass filter 4. In Figure 19, capacitor C1 is formed by capacitor conductor 461 and top layer 452, capacitor conductor 462 and top layer 452, and capacitor conductor 463 and top layer 452 respectively (Figure 18). Capacitor C4 is formed by capacitor conductor 461, floating conductor 481, and capacitor conductor 463 (Figure 18). Capacitor C5 is formed by capacitor conductor 462, floating conductor 482, and capacitor conductor 463 (Figure 18).

[0072] In Figure 20, the TL line represents the insertion loss relative to frequency, and the RL line represents the reflection loss relative to frequency. As shown in Figure 20, signals with frequencies below approximately 24.90 GHz are almost entirely reflected by bandpass filter 4 and cannot penetrate it. Signals with frequencies between approximately 24.90 and 25.50 GHz partially penetrate bandpass filter 4 and are partially reflected by it. Signals with frequencies between approximately 25.50 and 29.50 GHz mostly penetrate bandpass filter 4. The bandpass bandwidth of bandpass filter 4 is approximately 4.00 GHz, and its center frequency falls around 27.50 GHz. Signals with frequencies between approximately 29.50 and 31.25 GHz partially penetrate bandpass filter 4 and are partially reflected by it. Signals with frequencies above approximately 31.25 GHz are almost entirely reflected by bandpass filter 4 and cannot penetrate it. As can be seen, the bandwidth of bandpass filter 4 is approximately 4.00 GHz. This is compared to the bandwidth of bandpass filter 1 in Figure 5, which is approximately 3.00 GHz. Therefore, the bandpass filter 4 in this embodiment exhibits a wider bandwidth. In the RL line, five points P show a sharp drop in signal reflection loss, a number consistent with the number of resonant pillars 43 (one input / output resonant pillar 431, three intermediate resonant pillars 433, and one input / output resonant pillar 432). Based on this, it can be inferred that the more resonant pillars 43 there are, the wider the bandwidth of bandpass filter 4 may be.

[0073] Please refer to Figures 21 to 25. Figure 21 shows a perspective view of a bandpass filter according to another embodiment of the present invention. Figure 22 shows a top view of the bandpass filter of Figure 21. Figure 23 shows a left side view of the bandpass filter of Figure 21. Figure 24 shows an equivalent circuit diagram of the bandpass filter of Figure 21. Figure 25 shows a schematic diagram of the insertion loss and reflection loss of the bandpass filter of Figure 21 relative to frequency.

[0074] As shown in Figures 21 to 23, the bandpass filter 5 is similar to the bandpass filter 4 shown in Figures 16 to 20. The bandpass filter 5 includes a main body 51, two input / output posts 521 and 522, multiple resonant posts 53, two electrical connectors 541 and 542, a conductive cage 55, a first capacitor conductor 561, a second capacitor conductor 562, a third capacitor conductor 563, a fourth capacitor conductor 564, and a fifth capacitor conductor 565.

[0075] Input / output posts 521 and 522 are located on opposite sides of the main body 51 in the X direction. Resonant posts 53 are disposed within the main body 51. Each resonant post 53 has a first end 53a and a second end 53b. Each resonant post 53 includes two input / output resonant posts 531 and 532, a first intermediate resonant post 533, a second intermediate resonant post 534, and a third intermediate resonant post 535. Input / output resonant post 531 is adjacent to input / output post 521. Input / output resonant post 531 is electrically connected to input / output post 521 via electrical connector 541. Input / output resonant post 532 is adjacent to input / output post 522. Input / output resonant post 532 is electrically connected to input / output post 522 via electrical connector 542. The main body 51 is made of an insulating or dielectric material. Input / output posts 521, 522, and resonant posts 53 are made of a conductive material.

[0076] The resonant pillar 53 is located between the input / output pillars 521 and 522 in the X direction. That is, the projection of the resonant pillar 53 in the X direction lies between the projections of the input / output pillars 521 and 522 in the X direction. Specifically, the input / output pillar 521 is located on the positive X side of the resonant pillar 53, and the input / output pillar 522 is located on the negative X side of the resonant pillar 53. Furthermore, the first intermediate resonant pillar 533, the second intermediate resonant pillar 534, and the third intermediate resonant pillar 535 are located between the input / output resonant pillars 531 and 532 in the X direction. Specifically, the input / output resonant pillar 531 is located on the positive X side of the first intermediate resonant pillar 533, the second intermediate resonant pillar 534, and the third intermediate resonant pillar 535, and the input / output resonant pillar 532 is located on the negative X side of the first intermediate resonant pillar 533, the second intermediate resonant pillar 534, and the third intermediate resonant pillar 535.

[0077] A conductive cage 55 surrounds the resonant pillar 53 with its axis in the X direction. The conductive cage 55 includes a bottom layer 551, a top layer 552, and multiple side connectors 553 and 554. The two ends of the side connectors 553 and 554 are respectively connected to the bottom layer 551 and the top layer 552. The resonant pillar 53 is located between the bottom layer 551 and the top layer 552 in the Z direction. Specifically, the bottom layer 551 is located on the negative Z side of the resonant pillar 53, and the top layer 552 is located on the positive Z side of the resonant pillar 53. The resonant pillar 53 is located between the side connectors 553 and 554 in the Y direction. In this embodiment, the resonant pillar 53 is arranged in a serrated pattern.

[0078] As shown in Figures 22 and 23, the first end 53a of the resonant pillar 53 is connected to the bottom layer 551. The second end 53b of the resonant pillar 53 is spaced apart from the top layer 552. The conductive cage 55 is grounded. The input / output pillars 521 and 522 are closer to the bottom layer 551 and farther from the top layer 552. The height H1 of one of the input / output pillars 521 and 522 is one-quarter to one-half of the height H2 of one of the input / output resonant pillars 531 and 532. Electrical connectors 541 and 542 are located between the first end 53a and the second end 53b of the resonant pillar 53.

[0079] A first capacitor conductor 561, a second capacitor conductor 562, a third capacitor conductor 563, a fourth capacitor conductor 564, and a fifth capacitor conductor 565 are disposed within the main body 51 and are respectively connected to the second end 53b of the resonant pillar 53. Specifically, the first capacitor conductor 561 is connected to the second end 53b of the input / output resonant pillar 531. The second capacitor conductor 562 is connected to the second end 53b of the first intermediate resonant pillar 533. The third capacitor conductor 563 is connected to the second end 53b of the second intermediate resonant pillar 534. The fourth capacitor conductor 564 is connected to the second end 53b of the third intermediate resonant pillar 535. The fifth capacitor conductor 565 is connected to the second end 53b of the input / output resonant pillar 532. The first capacitor conductor 561, the second capacitor conductor 562, the third capacitor conductor 563, the fourth capacitor conductor 564, and the fifth capacitor conductor 565 are arranged to be spaced apart from the top layer 552, thereby forming a capacitor.

[0080] The minimum distances D1 from the input / output resonant pillar 531 to the side connector 553, D2 from the input / output resonant pillar 532 to the side connector 553, D3 from the first intermediate resonant pillar 533 to the side connector 553, D33 from the second intermediate resonant pillar 534 to the side connector 554, and D3 from the third intermediate resonant pillar 535 to the side connector 553 are all less than the minimum distances D4 and D5 between the resonant pillars 53.

[0081] There is a minimum distance D61 between the first intermediate resonant pillar 533 and the second intermediate resonant pillar 534; a minimum distance D62 between the second intermediate resonant pillar 534 and the third intermediate resonant pillar 535; and a minimum distance D63 between the first intermediate resonant pillar 533 and the third intermediate resonant pillar 535. The minimum distance D4 between the input / output resonant pillar 531 and the first intermediate resonant pillar 533 is less than the minimum distances D61, D62, and D63. The minimum distance D5 between the input / output resonant pillar 532 and the third intermediate resonant pillar 535 is less than the minimum distances D61, D62, and D63.

[0082] The distance D7 between the input / output resonant pillar 531 and the input / output resonant pillar 532 is greater than the distances D4, D5, D61, D62, and D63.

[0083] The angle θ1 between line L1 connecting the center of input / output resonant pillar 531 to the center of the nearest input / output pillar 521 and line L2 connecting the center of input / output resonant pillar 531 to the center of the first intermediate resonant pillar 533 is less than 90 degrees. The angle θ2 between line L3 connecting the center of input / output resonant pillar 532 to the center of the nearest input / output pillar 522 and line L4 connecting the center of input / output resonant pillar 532 to the center of the third intermediate resonant pillar 535 is less than 90 degrees.

[0084] The bandpass filter 5 in this embodiment further has the following features. The bandpass filter 5 further includes a floating conductor 582. The fifth capacitor conductor 565 connected to the input / output resonant pillar 532 and the fourth capacitor conductor 564 connected to the third intermediate resonant pillar 535 are adjacent to each other. The floating conductor 582 is arranged to overlap with and be spaced apart from the fifth capacitor conductor 565 and the fourth capacitor conductor 564. The floating conductor 582 is disposed between the first end 53a and the second end 53b of the resonant pillar 53. The floating conductors 581 and 582 are disposed closer to the second end 53b and farther from the first end 53a. The floating conductor 582 is electrically floating without being electrically connected to any component. Thereby, the fourth capacitor conductor 564, the floating conductor 582, and the fifth capacitor conductor 565 can form a capacitor.

[0085] Figures 24 and 25 illustrate the bandpass effect of bandpass filter 5. In Figure 24, capacitor C1 is formed by the first capacitor conductor 561 and top layer 552, the second capacitor conductor 562 and top layer 552, the third capacitor conductor 563 and top layer 552, the fourth capacitor conductor 564 and top layer 552, and the fifth capacitor conductor 565 and top layer 552 respectively (Figure 23). Capacitor C5 is formed by the fourth capacitor conductor 564, the floating conductor 582, and the fifth capacitor conductor 565 (Figure 23).

[0086] In Figure 25, the TL line represents the insertion loss relative to frequency, and the RL line represents the reflection loss relative to frequency. As shown in Figure 25, signals with frequencies below approximately 24.50 GHz are almost entirely reflected by bandpass filter 5 and cannot penetrate it. Signals with frequencies between approximately 24.50 and 25.50 GHz partially penetrate bandpass filter 5 and are partially reflected by it. Signals with frequencies between approximately 25.50 and 29.00 GHz mostly penetrate bandpass filter 5. The bandwidth of bandpass filter 5 is approximately 3.50 GHz, and its center frequency is approximately 27.25 GHz. Signals with frequencies between approximately 29.00 and 29.50 GHz partially penetrate bandpass filter 5 and are partially reflected by it. Signals with frequencies above approximately 29.50 GHz are almost entirely reflected by bandpass filter 5 and cannot penetrate it. Compared to the bandpass filter 1 in Figure 5, which has a bandpass bandwidth of approximately 3.00 GHz, the bandpass filter 5 in this embodiment has a wider bandpass bandwidth.

[0087] As can be seen, in the higher frequency band (29.0~29.50 GHz) where "the signal partially penetrates bandpass filter 5 and is partially reflected by bandpass filter 5", the bandwidth is approximately 0.5 GHz. In contrast, in Figure 20, in the higher frequency band (29.50~31.25 GHz) where "the signal partially penetrates bandpass filter 4 and is partially reflected by bandpass filter 4", the bandwidth is approximately 1.75 GHz. Therefore, in this embodiment, bandpass filter 5 exhibits a narrowing of the "band where it is difficult to distinguish whether the signal penetrates or not"—a band where "the signal partially penetrates bandpass filter 5 and is partially reflected by bandpass filter 5". Furthermore, the bandwidth of bandpass filter 5 at high frequencies drops more sharply at the high-frequency boundary than the bandwidth of bandpass filter 4 at the high-frequency boundary.

[0088] In summary, in one embodiment of the bandpass filter of the present invention, by connecting the first end of the resonant pillar to the bottom layer and setting the second end to be spaced from the top layer, the resonant pillar itself can form an inductance (L), and a capacitance (C) can be formed between the resonant pillar and the top layer, thus forming an inductor-capacitor (LC) type filter in a limited space. This allows the bandpass filter to meet the requirements of miniaturization. By setting the capacitive conductor, the capacitance can be increased, thereby adjusting the bandpass state of the bandpass filter. By setting the floating conductor, the capacitance arrangement in the equivalent circuit can be increased, thereby adjusting the bandpass state of the bandpass filter, such as the bandpass bandwidth, the bandwidth of the "band where it is difficult to distinguish whether a signal penetrates," etc.

[0089] While the present invention has been disclosed above with reference to the foregoing embodiments, it is not intended to limit the invention. Any modifications and refinements made without departing from the spirit and scope of the invention are within the scope of patent protection of the present invention. For details regarding the scope of protection defined in the present invention, please refer to the appended claims.

[0090] 1,2,3,4,5: Bandpass filters 11,21,31,41,51: Main body 121,122,221,222,321,322,421,422,521,522: Input / output columns 13,23,33,43,53: Resonance columns 13a, 23a, 33a, 43a, 53a: First end 13b, 23b, 33b, 43b, 53b: Second end 131,132,231,232,331,332,431,432,531,532: Input and output resonant pillars 133,233,333,433: Intermediate Resonance Columns 141,142,241,242,341,342,441,442,541,542: Electrical connectors 15, 25, 35, 45, 55: Conductive cage 151,251,351,451,551: Bottom layer 152,252,352,452,552: Top layer 153,154,253,254,353,354,453,454,553,554: Side connectors 161,162,163,261,262,263,361,362,363,461,462,463: Capacitive conductors 37,481,482,582: Floating conductors 533: First Intermediate Resonance Column 534: Second Intermediate Resonance Column 535: Third Intermediate Resonance Column 561: First capacitor conductor 562: Second capacitor conductor 563: Third capacitor conductor 564: Fourth capacitor conductor 565: Fifth capacitor conductor C1, C2, C3, C4, C5: Capacitors D1, D2, D3, D4, D5, D6, D7, D21, D22, D23, D24, D33, D61, D62, D63: Distance H1, H2: Height L1, L2, L3, L4: Connecting lines P: Point RL: Reflection Loss Line TL: Insertion Loss Line θ1, θ2: included angle

Claims

1. A bandpass filter, comprising: One main body; Two input / output posts are located on opposite sides of the main body in one direction; Multiple resonant pillars are disposed within the main body, each resonant pillar having a first end and a second end. These resonant pillars include: two input / output resonant pillars, respectively adjacent to and electrically connected to the two input / output pillars; and multiple intermediate resonant pillars located between the two input / output resonant pillars in this direction, including a first intermediate resonant pillar, a second intermediate resonant pillar, and a third intermediate resonant pillar, the first and third intermediate resonant pillars being adjacent to the two input / output resonant pillars respectively; multiple capacitor conductors and a floating conductor, the capacitor conductors being disposed within the main body and respectively connected to the second ends of the resonant pillars, the capacitor conductors including a first capacitor conductor, a second capacitor conductor, a third capacitor conductor, a fourth capacitor conductor, and a fifth capacitor conductor, the first and fifth capacitor conductors being respectively connected to the two input / output resonant pillars, the second capacitor conductor... The body, the third capacitor conductor, and the fourth capacitor conductor are respectively connected to the first intermediate resonant pillar, the second intermediate resonant pillar, and the third intermediate resonant pillar. The floating conductor is arranged to overlap with and be spaced apart from the fourth capacitor conductor and the fifth capacitor conductor. A conductive cage surrounds the resonant pillars. The conductive cage includes a bottom layer, a top layer, and a plurality of side connectors. The side connectors are connected to the bottom layer and the top layer. The first ends of the resonant pillars are connected to the bottom layer. The second ends of the resonant pillars are spaced apart from the top layer. The minimum distance between each resonant pillar and one of the side connectors is less than the minimum distance between the resonant pillars. The capacitor conductors are spaced apart from the top layer. The two input / output pillars, the resonant pillars, and the side connectors are substantially parallel to each other and substantially perpendicular to the bottom layer and the top layer. One end of each input / output pillar, one end of each resonant pillar, and one end of each side connector are connected to the bottom layer.

2. The bandpass filter as described in claim 1, wherein the body is made of ceramic.

3. The bandpass filter as described in claim 1, wherein the conductive cage is configured to be grounded.

4. The bandpass filter as claimed in claim 1, wherein a distance between the two input-output resonant pillars is greater than a plurality of distances between two other adjacent resonant pillars.

5. The bandpass filter as described in claim 1, wherein the side connectors are a plurality of connecting posts, the two ends of which are respectively connected to the bottom layer and the top layer.

6. The bandpass filter as claimed in claim 1, wherein a minimum distance between each of the input / output resonant pillars and the intermediate resonant pillars is less than a minimum distance between two adjacent intermediate resonant pillars.

7. The bandpass filter as described in claim 1, wherein the two input / output pillars are closer to the bottom layer and farther from the top layer, and the height of one of the input / output pillars is one-quarter to one-half the height of one of the input / output resonant pillars.

8. The bandpass filter as claimed in claim 1, wherein the angle between the line connecting each of the input / output resonant pillars to the nearest input / output pillar and the line connecting each of the input / output resonant pillars to the nearest intermediate resonant pillar is less than 90 degrees.

9. The bandpass filter as claimed in claim 1, wherein the floating conductor is disposed between the first ends and the second ends of the resonant pillars, the floating conductor being disposed closer to the second ends and farther away from the first ends.

10. A bandpass filter, comprising: One main body; Two input / output posts are located on opposite sides of the main body in one direction; A plurality of resonant pillars are disposed within the main body, each resonant pillar having a first end and a second end. The resonant pillars include: two input / output resonant pillars, respectively adjacent to and electrically connected to the two input / output pillars; and a plurality of intermediate resonant pillars located between the two input / output resonant pillars in this direction, the intermediate resonant pillars including a first intermediate resonant pillar, a second intermediate resonant pillar, and a third intermediate resonant pillar, the first and third intermediate resonant pillars being adjacent to the two input / output resonant pillars respectively; a plurality of capacitive conductors and a floating conductor, the capacitive conductors being disposed within the main body and respectively connected to the second ends of the resonant pillars, the capacitive conductors including a first capacitive conductor, a second capacitive conductor, a third capacitive conductor, a fourth capacitive conductor, and a fifth capacitive conductor, the first and fifth capacitive conductors being respectively connected to the two input / output pillars. The system comprises a resonant column, a second capacitor conductor, a third capacitor conductor, and a fourth capacitor conductor respectively connected to the first intermediate resonant column, the second intermediate resonant column, and the third intermediate resonant column; a floating conductor configured to overlap with and be spaced apart from the fourth capacitor conductor and the fifth capacitor conductor; and a conductive cage surrounding the resonant columns, the conductive cage including a bottom layer, a top layer, and a plurality of side connectors, the side connectors connecting the bottom layer and the top layer; the first ends of the resonant columns connected to the bottom layer; the second ends of the resonant columns spaced apart from the top layer; a minimum distance between each resonant column and one of the side connectors being less than a minimum distance between the resonant columns; and capacitor conductors spaced apart from the top layer; and an angle less than 90 degrees between the line connecting each input / output resonant column to the nearest input / output column and the line connecting each input / output resonant column to the nearest intermediate resonant column.

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