Patent ID: 12230853

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present disclosure will be described in detail below with reference to the drawings, where like features are denoted by the same reference labels throughout the detailed description of the drawings. Unless noted otherwise, features with the same name, but with different letters ending their reference number, have the same features. For example, “first resonator10”, “first resonator10A”, “first resonator10B”, and “first resonator10D” share the same characteristics unless an alternate description is provided.

First Embodiment

FIG.1is a perspective view illustrating a band-pass filter of the first embodiment of the present disclosure.FIG.2is a longitudinal sectional view taken along line A-A ofFIG.1.FIG.3Ais a plan view illustrating the band-pass filter of the first embodiment.FIG.3Bis a sectional view taken along line B1-B1ofFIG.2.FIG.3Cis a sectional view taken along line B2-B2ofFIG.2.FIG.4Ais a sectional view taken along line B3-B3ofFIG.2.FIG.4Bis a bottom view illustrating the band-pass filter of the first embodiment. In the following description, the axial direction of conductor pins11and31of a band-pass filter1will be defined as a “height direction”, and a direction perpendicular to the axial direction will be defined as a “transverse direction”. The height direction and the transverse direction mentioned in the specification do not need to match the height direction and the transverse direction during use.

The band-pass filter1of the first embodiment includes a first resonator10and a second resonator30that are electromagnetically coupled to each other. The first resonator10and the second resonator30are arranged in the height direction. The first resonator10and the second resonator30may be integrally formed. The second resonator30is an input resonator to which a signal that passes through a filter is input from the outside. The first resonator10is an output resonator that outputs a signal that has passed through the band-pass filter1to the outside. The first resonator10and the second resonator30are electromagnetically coupled to each other by transmitting an electromagnetic field through an opening21hof a second surrounding conductor21. The first resonator10and the second resonator30each correspond to an example of a specific resonator according to the present disclosure.

The first resonator10includes the conductor pin11, a first surrounding conductor12that surrounds the conductor pin11in a radial direction, a dielectric13that is positioned between the conductor pin11and the first surrounding conductor12, a second surrounding conductor14, the second surrounding conductor21, and a first intermediate conductor15that extends from the conductor pin11to the first surrounding conductor12. The second surrounding conductors14and21surround the dielectric13from the upper and lower sides. The dielectric13occupies a region that is surrounded by the first surrounding conductor12. The dielectric13may be extended to a region outside the first surrounding conductor12. The first intermediate conductor15corresponds to an example of an intermediate conductor according to the present disclosure.

The conductor pin11extends in the height direction and has a first end portion extending to the height of the second surrounding conductor14and a second end portion11t(FIG.2) extending to a height that is spaced apart from the second surrounding conductor21. The first end portion of the conductor pin11is positioned in an opening14hof the second surrounding conductor14, and the first end portion of the conductor pin11is exposed to the outside or connected to a connection pad11pthat is exposed through the opening14h. The first end portion of the conductor pin11and the connection pad11pare located inside the inner periphery of the opening14hand are not in contact with the second surrounding conductor14. The conductor pin11is connected to an external signal line through the opening14hand outputs a signal that has passed through the band-pass filter1. The conductor pin11may be formed by injecting a conductor into a via hole of the dielectric13and may be referred to as an output via.

The first surrounding conductor12includes a plurality of pin-shaped conductors12a, and the plurality of conductors12aare arranged so as to be spaced apart from one another. The plurality of conductors12amay be arranged in a cylindrical arrangement, or any of various arrangements such as a rectangular arrangement and a polygonal arrangement with which the plurality of conductors12asurround the conductor pin11in the radial direction when viewed in the height direction may be employed. In the height direction, one end of the first surrounding conductor12is connected to the second surrounding conductor14located on the upper side, and the other end of the first surrounding conductor12is connected to the second surrounding conductor21located on the lower side. The pitch of the pin-shaped conductors12a, which are included in the first surrounding conductor12, is set to a pitch at which leakage of electromagnetic waves at a resonance frequency is suppressed. The first surrounding conductor12may be grounded through the second surrounding conductors14and21. Each of the pin-shaped conductors12amay be formed by injecting a conductor into a via hole of the dielectric13. Note that the first surrounding conductor12may be a tubular conductor wall that surrounds the conductor pin11.

The second surrounding conductors14and21are each a planar or film-shaped conductor that extends two-dimensionally in the transverse direction, and in a region including the region surrounded by the first surrounding conductor12, the dielectric13is sandwiched between the second surrounding conductors14and21in the vertical direction. The second surrounding conductor14has the opening14hthrough which the first end of the conductor pin11or the connection pad11pis exposed to the outside. The second surrounding conductor21has the opening21hthrough which an electromagnetic field is transmitted from the second resonator30. The second surrounding conductors14and21may be grounded and referred to as ground conductors.

The first intermediate conductor15is a conductor that is long in one direction and that has a linear shape or a belt-like shape and extends in the transverse direction from the second end portion11tof the conductor pin11in the dielectric13so as to electrically connect the second end portion11tof the conductor pin11and a portion (e.g., one of the pin-shaped conductors12a) of the first surrounding conductor12to each other. When viewed from above, the first intermediate conductor15may have a shape extending along a straight line or may have a shape extending along a curved line. The curved line may be a meandering line or may have a corner portion. In addition, when viewed in the transverse direction, the first intermediate conductor15may have a shape extending in the horizontal direction or may include a portion having a shape extending obliquely as long as the first intermediate conductor15extends in a direction crossing the height direction.

The second resonator30includes the conductor pin31, a first surrounding conductor32that surrounds the conductor pin31in the radial direction, a dielectric33that is positioned between the conductor pin31and the first surrounding conductor32, the second surrounding conductor21and a second surrounding conductor34that surround the dielectric33from the upper and lower sides, and a second intermediate conductor35that extends from the conductor pin31to the first surrounding conductor32. The second surrounding conductor21may be a conductor shared by the first resonator10. The second intermediate conductor35corresponds to an example of the intermediate conductor according to the present disclosure.

The conductor pin31extends in the height direction and has a first end portion extending to the height of the second surrounding conductor34and a second end portion31t(FIG.2) extending to a height that is spaced apart from the second surrounding conductor21. The first end portion of the conductor pin31is exposed through an opening34hof the second surrounding conductor34or connected to a connection pad31pthat is exposed through the opening34h. The first end portion of the conductor pin31and the connection pad31pare located inside the inner periphery of the opening34hand are not in contact with the second surrounding conductor34. A signal that passes through the band-pass filter1is input to the conductor pin31from an external signal line through the opening34h. The conductor pin31may be formed by injecting a conductor into a via hole of the dielectric33and may be referred to as an input via.

The dielectric33is continuous with the dielectric13of the first resonator10via the opening21hand may be integrated with the dielectric13of the first resonator10. The dielectric33occupies a region that is surrounded by the first surrounding conductor32. The dielectric33may be extended to a region outside the first surrounding conductor32.

The first surrounding conductor32is configured in a manner similar to the first surrounding conductor12of the first resonator10except that the first surrounding conductor32is positioned between the second surrounding conductors34and21. The second surrounding conductors34and21are configured in a manner similar to the second surrounding conductors14and21of the first resonator10except that they are turned upside down.

The second intermediate conductor35is a conductor that is long in one direction and that has a linear shape or a belt-like shape and extends in the transverse direction from the second end portion31tof the conductor pin31so as to electrically connect the second end portion31tof the conductor pin31and a portion (e.g., one of pin-shaped conductors32a) of the first surrounding conductor32to each other. When viewed from above, the second intermediate conductor35may have a shape extending along a straight line or may have a shape extending along a curved line. The curved line may be a meandering line or may have a corner portion. In addition, when viewed in the transverse direction, the second intermediate conductor35may have a shape extending in the horizontal direction or may include a portion having a shape extending obliquely. The second intermediate conductor35may be shaped such that the second intermediate conductor35and the first intermediate conductor15are symmetrical in shape or may have a different shape. The second intermediate conductor35and the first intermediate conductor15may be symmetrically arranged or may be asymmetrically arranged.

<Description of Operation>

The first resonator10resonates as a result of electromagnetic energy being confined to the dielectric13surrounded by the first surrounding conductor12and the second surrounding conductors14and21. The distribution of an electromagnetic field vibrates at a vibration frequency and in a vibration mode that are determined by a boundary condition based on the arrangement of the first surrounding conductor12and the arrangement of the conductor pin11and by a capacitance component and an inductance component associated with among the conductors and the dielectric13.

In the first resonator10, an inductance component is generated by the conductor pin11and the dielectric13, which are arranged around the conductor pin11, and a capacitance component is generated between the conductor pin11and the first surrounding conductor12. In addition, in the first resonator10, the second end portion11tof the conductor pin11is positioned so as to be spaced apart from the second surrounding conductor21, and the first intermediate conductor15and the second surrounding conductor21are arranged so as to face each other, so that a capacitance component is generated between the second end portion11tof the conductor pin11and the second surrounding conductor21and between the first intermediate conductor15and the second surrounding conductor21. Furthermore, a current flows through the first intermediate conductor15from the side on which the conductor pin11is disposed to the side on which the first surrounding conductor12is disposed, and thus, an inductance component is generated in the first intermediate conductor15.

When the first resonator10is reduced in size and designed with a high resonant frequency, the space between the conductor pin11and the first surrounding conductor12is reduced, and thus, the capacitance component there between increases. If only the capacitance component increases, it becomes difficult to match the first resonator10to a predetermined impedance. However, in the first resonator10of the first embodiment, since an inductance component is added to the first intermediate conductor15, the magnitude of the inductance component that is added to the first intermediate conductor15can be changed by changing the path and the length of the first intermediate conductor15. Thus, by suitably designing the first intermediate conductor15in accordance with the capacitance component of the first resonator10, the inductance component can be adjusted.

In the first resonator10, the first intermediate conductor15is suitably designed, and an adjusted inductance component is added to the first intermediate conductor15, so that impedance matching of the first resonator10is achieved while the first resonator10is smaller in size and has resonance characteristics in a predetermined high-frequency band.

Similar to the first resonator10, in the second resonator30, an adjusted inductance component is added by suitably designing the second intermediate conductor35, so that impedance matching of the second resonator30is achieved while the second resonator30is smaller in size and has resonance characteristics in a predetermined high-frequency band.

At the time of using the band-pass filter1, when a signal is input to the conductor pin31of the second resonator30, a frequency component that is included in the input signal and that resonates in the second resonator30and the first resonator10resonates and is transmitted from the second resonator30to the first resonator10. Then, a signal of the resonated frequency component is output to the outside via the conductor pin11of the first resonator10. In contrast, a frequency component that is included in the input signal and that is different from a resonant frequency is attenuated while passing through the second resonator30and the first resonator10. Thus, a signal component in a resonant frequency band can be extracted through the band-pass filter1.

The signal enters the second resonator30from the outside, passes through the second resonator30and the first resonator10, and exits from the first resonator10to the outside. In addition, the impedance of the first resonator10and the impedance of the second resonator30are each suitably matched with an external signal line. Thus, when a resonant frequency signal is input from the outside to the second resonator30, passes through the second resonator30and the first resonator10and is output from the first resonator10to the outside, reflection of the signal is suppressed. Therefore, a high transmittance of the band-pass filter1is achieved.

As described above, according to the band-pass filter1of the first embodiment, the first resonator10includes the first intermediate conductor15that extends from the conductor pin11in the transverse direction and that is connected to the first surrounding conductor12, and the second resonator30includes the second intermediate conductor35that extends from the conductor pin31in the transverse direction and that is connected to the first surrounding conductor32. In addition, by the first intermediate conductor15and the second intermediate conductor35, an inductance component can be added to the first resonator10and the second resonator30in addition to a capacitance component. Furthermore, by changing the designs of the first intermediate conductor15and the second intermediate conductor35, the capacitance component and the inductance component, which have been mentioned above, can be adjusted in such a manner that the degrees of their changes are different from each other. Thus, the degree of freedom when designing the impedance of the first resonator10and the impedance of the second resonator30is improved. Therefore, by suitably designing the first intermediate conductor15and the second intermediate conductor35, the band-pass filter1that is matched with a predetermined impedance while, for example, being reduced in size and having resonance characteristics in a predetermined high-frequency band can be achieved.

In addition, according to the band-pass filter1of the first embodiment, the end portions of the conductor pins11and31are spaced apart from the second surrounding conductor21. Thus, the current that flows into the conductor pins11and31flows into the first intermediate conductor15and the second intermediate conductor35, and the inductance component of the first intermediate conductor15and the inductance component of the second intermediate conductor35can be further increased.

Furthermore, according to the band-pass filter1of the first embodiment, the second end portions11tand31tof the conductor pins11and31are respectively connected to the first intermediate conductor15and the second intermediate conductor35. Here, a plurality of design patterns are assumed in which the first intermediate conductor15and the second intermediate conductor35are fixed at a certain height. When comparing the plurality of design patterns, the distance between each of the conductor pins11and31and the second surrounding conductor21becomes maximum with the configuration of the first embodiment in which the second end portions11tand31tof the conductor pins11and31are respectively connected to the first intermediate conductor15and the second intermediate conductor35. In other words, in a design pattern in which the second end portion11tof the conductor pin11projects toward the second surrounding conductor21beyond the first intermediate conductor15and in which the second end portion31tof the conductor pin31projects toward the second surrounding conductor21beyond the second intermediate conductor35, the distance between each of the conductor pins11and31and the second surrounding conductor21is shorter than that in the design pattern of the first embodiment. Where in the first embodiment, the second end portion11tof the conductor pin11does not project toward the second surrounding conductor21beyond the first intermediate conductor15and the second end portion31tof the conductor pin31does not project toward the second surrounding conductor21beyond the second intermediate conductor35. Thus, by employing the configuration of the first embodiment, the distance between each of the second end portions11tand31tof the conductor pins11and31and the second surrounding conductor21can be increased, and the capacitance component that is generated between each of the second end portions11tand31tof the conductor pins11and31and the second surrounding conductor21can be reduced. Therefore, the ratio of the inductance component to the overall capacitance component of the first resonator10or the second resonator30can be improved. In addition, according to the configuration in which the second end portions11tand31tof the conductor pins11and31are respectively connected to the first intermediate conductor15and the second intermediate conductor35, since the second end portion11tof the conductor pin11and the first intermediate conductor15are located at the same height, and the second end portion31tof the conductor pin31and the second intermediate conductor35are located at the same height, when the band-pass filter1is manufactured by stacking the conductors of layers on top of one another, simplification of the manufacturing process can be achieved. More specifically, a step of providing a through conductor that enables the conductor pin11to project from the bottom surface of the first intermediate conductor15and a through conductor that enables the conductor pin31to project from the top surface of the second intermediate conductor35can be omitted. Furthermore, according to the configuration in which the second end portions11tand31tof the conductor pins11and31are respectively connected to the first intermediate conductor15and the second intermediate conductor35, the capacitance component between the second surrounding conductor21and the conductor pins11and31is determined by the area of the first intermediate conductor15and the area of the second intermediate conductor35, and it is not necessary to adjust the capacitance component between the second end portions11tand31tof the conductor pins11and31separately, so that the design for adjusting a resonant frequency and an impedance can be made easily.

In addition, according to the band-pass filter1of the first embodiment, since the first resonator10and the second resonator30are stacked one on top of the other in the height direction, a reduction of the surface area of the band-pass filter1when viewed in the height direction can be achieved. Furthermore, since the first resonator10and the second resonator30are stacked one on top of the other in the height direction, a signal can be input to the second resonator30from one side in the height direction, and a signal can be output from the other side in the height direction. Therefore, in a communication device in which an antenna element, the band-pass filter1, and a circuit board that processes a frequency-extracted signal are stacked on top of one another in this order, simplification and shortening of a signal line between the antenna element and the band-pass filter1and a signal line between the band-pass filter1and the circuit board can be achieved.

Second Embodiment

FIG.5is a longitudinal sectional view illustrating a band-pass filter according to the second embodiment of the present disclosure. The configuration of a band-pass filter1A of the second embodiment is similar to that of the band-pass filter1of the first embodiment, except with regard to the arrangement of a first intermediate conductor15A and a second intermediate conductor35A. The first intermediate conductor15A and the second intermediate conductor35A each correspond to an example of the intermediate conductor according to the present disclosure.

The first intermediate conductor15A extends in the transverse direction so as to connect an intermediate portion of the conductor pin11in the height direction and the pin-shaped conductors12aof the first surrounding conductor12to each other. Similarly, the second intermediate conductor35A extends in the transverse direction so as to connect an intermediate portion of the conductor pin31in the height direction and the pin-shaped conductors32aof the first surrounding conductor32to each other.

According to the band-pass filter1A of the second embodiment, in a first resonator10A, the length of the conductor pin11and the arrangement of the first intermediate conductor15A in the height direction can be design parameters that are independent of each other. Thus, a design change can be made to the capacitance component between the second end portion11tof the conductor pin11and the second surrounding conductor21by changing the length of the conductor pin11, and design changes can be made to the capacitance component and the inductance component that are added to the first intermediate conductor15A by changing the arrangement of the first intermediate conductor15A. Therefore, with the above-described configuration, the degree of freedom when designing the overall capacitance component and the overall inductance component of the first resonator10A is further improved, and a reduction in size, desired frequency characteristics, and impedance matching can be further easily achieved. The same degree of freedom applies to a second resonator30A, and as a result, a reduction in the size of the band-pass filter1A, desired frequency characteristics, and impedance matching can be further easily achieved.

Third Embodiment

FIG.6is a longitudinal sectional view illustrating a band-pass filter according to the third embodiment of the present disclosure. The configuration of a band-pass filter1B of the third embodiment is similar to that of the band-pass filter1of the first embodiment or the band-pass filter1A of the second embodiment except that the band-pass filter1B further includes connection pins16B and36B and that a first intermediate conductor15B and a second intermediate conductor35B are connected to different members. The first intermediate conductor15B and the second intermediate conductor35B each correspond to an example of the intermediate conductor according to the present disclosure.

In a first resonator10B, one end of the first intermediate conductor15B is connected to the conductor pin11, and the other end of the first intermediate conductor15B is connected to the second surrounding conductor14via the connection pin16B. In other words, the other end of the first intermediate conductor15B is spaced apart from the first surrounding conductor12. The connection pin16B is a pin-shaped conductor extending in the height direction and is positioned so as to be spaced apart from the conductor pin11in the transverse direction. The connection pin16B may be configured such that one end portion thereof is located at the same height as the first intermediate conductor15B.

In a second resonator30B, one end of the second intermediate conductor35B is connected to the conductor pin31, and the other end of the second intermediate conductor35B is connected to the second surrounding conductor34via the connection pin36B. In other words, the other end of the second intermediate conductor35B is spaced apart from the first surrounding conductor32. The connection pin36B is a pin-shaped conductor extending in the height direction and is positioned so as to be spaced apart from the conductor pin31in the transverse direction. The connection pin36B may be configured such that one end portion thereof is located at the same height as the second intermediate conductor35B.

The connection pins16B and36B may be formed by injecting a conductor into via holes of the dielectrics13and33and may each be referred to as a connection via.

Note that, inFIG.6, although the first intermediate conductor15B is connected to an intermediate portion of the conductor pin11in a length direction, the first intermediate conductor15B may be connected to the second end portion11tof the conductor pin11. In addition, although the connection pin16B is connected to the second surrounding conductor14located on the upper side inFIG.6, the connection pin16B may be connected to the second surrounding conductor21located on the lower side and may be spaced apart from the second surrounding conductor14located on the upper side. The same applies to the second intermediate conductor35B and the connection pin36B of the second resonator30B.

According to the band-pass filter1B of the third embodiment, the degree of freedom when designing the terminal position of the first intermediate conductor15B and the terminal position of the second intermediate conductor35B can be improved, and for example, the first intermediate conductor15B and the second intermediate conductor35B can be shorter than those in each of the configurations of the first and second embodiments. Also in the case of employing a configuration in which the first intermediate conductor15B is connected to the second surrounding conductor14via the connection pin16B and in which the second intermediate conductor35B is connected to the second surrounding conductor34via the connection pin36B, an inductance component is added to the first intermediate conductor15B and the terminal position of the second intermediate conductor35B, and this can contribute to impedance matching.

Fourth Embodiment

FIG.7Ais a plan view illustrating a band-pass filter of the fourth embodiment of the present disclosure.FIG.7Bis a longitudinal sectional view taken along line C-C ofFIG.7A.

A band-pass filter1C of the fourth embodiment includes four resonators10C,30C,50, and70that are electromagnetically coupled to one another. The two resonators30C and70that are adjacent to each other in the transverse direction are electromagnetically coupled by connecting the dielectric33and a dielectric73to each other, and the two resonators70and50that are adjacent to each other in the vertical direction are electromagnetically coupled by connecting the dielectric73and a dielectric53to each other through an opening61hof a second surrounding conductor61(FIG.7B). The other two resonators50and10C that are adjacent to each other in the transverse direction are electromagnetically coupled by connecting the dielectric53and the dielectric13to each other. The electromagnetic coupling of the resonators30C and70, which are adjacent to each other in the transverse direction, may be achieved by causing a region that is surrounded by the first surrounding conductor32and a region that is surrounded by a first surrounding conductor72to partially overlap each other and by spacing at least one of the pin-shaped conductors32aand at least one of pin-shaped conductors72athat are arranged in the overlapping region apart from each other by a distance that allows an electromagnetic field at a resonant frequency to pass therethrough. This is common to the electromagnetic coupling of the resonators50and10C. In the band-pass filter1C, the resonators10C and30C correspond to an example of a “first pair of resonators that are arranged in the axial direction” and “specific resonators” according to the present disclosure, and the resonators50and70correspond to an example of a “second pair of resonators that are arranged in the axial direction” and “non-specific resonators” according to the present disclosure.

The resonators10C and30C are similar to the first resonator10and the second resonator30of the first embodiment except with regard to the following: the second surrounding conductor21(FIG.7B) that is positioned between the resonators10C and30C does not have an opening, a portion of the pin-shaped conductors12aof the first surrounding conductor12include a portion that is opened by the above-mentioned distance, and a portion of the pin-shaped conductors32aof the first surrounding conductor32include a portion that is opened by the above-mentioned distance.

The resonator50includes a conductor pin51, a first surrounding conductor52that surrounds the conductor pin51in the radial direction, the dielectric53that occupies a region between the conductor pin51and the first surrounding conductor52, a second surrounding conductor54, and the second surrounding conductor61. The second surrounding conductors54and61surround the dielectric53from the upper and lower sides.

The resonator70includes a conductor pin71, the first surrounding conductor72that surrounds the conductor pin71in the radial direction, the dielectric73that occupies a region between the conductor pin71and the first surrounding conductor72, a second surrounding conductor74(FIG.7B), and the second surrounding conductor61. The second surrounding conductors74and61surround the dielectric73from the upper and lower sides.

In the plurality of resonators10C,30C,50, and70, the dielectrics53,73,13, and33may be integrally formed so as to be continuous with one another. The second surrounding conductors14and54that are adjacent to each other in the transverse direction and that are located at the same height may be an integrally formed conductor. This is common to the other second surrounding conductors21and61that are adjacent to each other in the transverse direction and the other second surrounding conductors34and74(FIG.7B) that are adjacent to each other in the transverse direction.

The conductor pins51and71extend in the height direction. One end of the conductor pin51is connected to the second surrounding conductor54, and one end of the conductor pin71is connected to the second surrounding conductor74. The other ends of the conductor pins51and71are spaced apart from the second surrounding conductor61. Note that the conductor pin51may be connected to both the second surrounding conductor54on the upper side and the second surrounding conductor61on the lower side. Alternatively, the conductor pin51may be spaced apart from the second surrounding conductor54on the upper side and may be connected to the second surrounding conductor61on the lower side. The conductor pin71may be connected to both the second surrounding conductor61on the upper side and the second surrounding conductor74on the lower side. Alternatively, the conductor pin71may be connected to the second surrounding conductor61on the upper side and may be spaced apart from the second surrounding conductor74on the lower side.

The first surrounding conductors52/52aand72/72ahave configurations similar to those of the first surrounding conductors12and32of the first embodiment except that, in a portion in which the resonator10C and30C face each other, the pitch of first surrounding conductors52aand the pitch of first surrounding conductors72aare each wider than that of the other portions. The second surrounding conductors54and74have configurations similar to those of the second surrounding conductors14and34of the first embodiment except that the second surrounding conductors54and74do not have either the opening14hor the opening34hand that the one end of the conductor pin51and the one end of the conductor pin71are respectively connected to the second surrounding conductor54and the second surrounding conductor74. The second surrounding conductor61has a configuration similar to that of the second surrounding conductor21of the first embodiment.

In the band-pass filter1C of the fourth embodiment, the resonator30C corresponds to an input resonator to which a signal is input, and the resonator10C corresponds to an output resonator that outputs a signal. The pair of resonators30C and10C to or from which a signal is input or output include the first intermediate conductor15(FIG.7B) and the second intermediate conductor35(FIG.7B) and may be arranged in the height direction. A signal passes though the pair of resonators50and70. The pair of resonators50and70do not include intermediate conductors that extend from the conductor pins51and71in the transverse direction and the pair of resonators50and70may be arranged in the height direction. The area when the resonators10C and30C are viewed in the height direction (the area of a region that is surrounded by the first surrounding conductors12and32) and the area when the resonators50and70are viewed in the height direction (the area of a region that is surrounded by the first surrounding conductors52and72) may be different from each other.

In the band-pass filter1C of the fourth embodiment, a signal in a resonant frequency band among the signals input to the resonator30C through a signal line is transmitted to each of the resonators30C,70,50, and10C while resonating and is output by the resonator10C on the output side to which the signal line is connected. In contrast, a signal outside the resonant frequency band is attenuated by each of the resonators30C,70,50, and10C. Thus, a signal component in the resonant frequency band can be extracted through the band-pass filter1C. Note that the second surrounding conductor21between the resonators10C and30C may have an opening, and in this case, a signal that is input to the resonator30C partially and directly propagates from the resonator30C to the resonator10C and is output to the outside.

According to the band-pass filter1C of the fourth embodiment, by suitably setting the frequencies of resonance peaks of the plurality of resonators30C,70,50, and10C to be different values, for example, while a signal pass band is widened to a predetermined width, a desired filter characteristic such as a characteristic that the transmittance sharply drops at a boundary of the pass band can be easily achieved.

In addition, according to the band-pass filter1C of the fourth embodiment, by employing a configuration in which the resonators10C and30C, which respectively correspond to the output resonator and the input resonator, include the first intermediate conductor15and the second intermediate conductor35, impedance matching with signal input and output lines can be achieved, and the filter characteristics can be improved.

Furthermore, according to the band-pass filter1C of the fourth embodiment, the resonator10C including the first intermediate conductor15and the resonator30C including the second intermediate conductor35are arranged in the height direction, and the resonators50and70that do not include intermediate conductors that extend from the conductor pins51and71in the transverse direction are arranged in the height direction. Such arrangements can reduce the surface area of the band-pass filter1C when viewed in the height direction compared with a configuration in which all of the four resonators are arranged in the transverse direction. In addition, the resonator10C, which is the input resonator, and the resonator30C, which is the output resonator, are arranged one above the other, and thus, when a communication device is formed by stacking an antenna element, the band-pass filter1C, and a circuit board that processes a frequency-extracted signal on top of one another, simplification and shortening of signal lines between them can be achieved.

<Simulation Results>

FIG.8Ais a graph illustrating filter characteristics of the band-pass filter of the fourth embodiment.FIG.8Bis a comparative example toFIG.8Aand is a graph illustrating filter characteristics of a different band-pass filter than that of the fourth embodiment. A band-pass filter of the comparative example has the same size as the resonators10C,30C,50, and70of the fourth embodiment and employs a structure that does not include the first intermediate conductor15and the second intermediate conductor35. In addition, the band-pass filter of the comparative example has a configuration in which design parameters (the length of the conductor pins11,31,51, and71) are optimized so as to be closest to a desired frequency characteristic and a desired impedance. In the simulations, calculations were performed by assuming each of the first surrounding conductors12,32,52,72as a cylindrical wall body for simplification.

As illustrated inFIG.8A, in the band-pass filter1C of the fourth embodiment, a uniform transmittance in dB was obtained in a pass frequency band. In contrast, as illustrated inFIG.8B, in the band-pass filter of the comparative example, a ripple R was generated in the transmittance in dB over the pass frequency band. The ripple R is generated due to an impedance mismatch in the band-pass filter of the comparative example.

It is understood from the simulation results that, in the case where a pass frequency is set in a desired high-frequency band by reducing the size of a band-pass filter, impedance matching cannot be achieved with the structure of the comparative example, whereas by employing the structure of the embodiment, impedance matching is achieved, and favorable filter characteristics can be obtained.

(First Modification)

FIG.9is a schematic diagram illustrating a band-pass filter of the first modification. InFIG.9, the order in which a signal propagates resonators is indicated by a one-dot chain line.

In the above-described first to fourth embodiments, the configurations have been described in each of which one of the first resonators10,10A, and10B each of which outputs a signal and a corresponding one of the second resonators30,30A, and30B to each of which a signal is input are arranged in the vertical direction (the axial direction of the conductor pins). However, like a band-pass filter1D of the first modification, a configuration in which a first resonator10D that outputs a signal and a second resonator30D to which a signal is input are arranged in the transverse direction (a direction crossing the axial direction) may be employed. The first resonator10D illustrated inFIG.9has a configuration similar to that of each of the first resonators10,10A, and10B illustrated inFIG.1toFIG.6, and the second resonator30D illustrated inFIG.9has a configuration similar to that of each of the second resonator30,30A, and30B illustrated inFIG.1toFIG.6. However, the opening21hof the second surrounding conductor21ifFIG.2is not provided herein, and the space between portions of each first surrounding conductor is increased as in the resonators10C and50that are arranged in the transverse direction inFIG.7, so that electromagnetic coupling to the first resonator10D and the second resonator30D is achieved through the space.

In the band-pass filter1D of the first modification, a signal input unit (the connection pad31por an end portion of the conductor pin31) and a signal output unit (the connection pad11por an end portion of the conductor pin11) are arranged on the same side (the lower surface side of the band-pass filter1D).

According to the band-pass filter1D of the first modification, a reduction in the height of a device can be achieved by the arrangement of the first resonator10D and the second resonator30D. In addition, since the signal input unit and the signal output unit are arranged on the same side, a surface mount device can be obtained.

Note that the first resonator10D illustrated inFIG.9may be disposed upside down, and the signal output unit may be positioned on a surface that is opposite to the surface on which the signal input unit is positioned. With such a configuration, a configuration in which a signal is input in one direction and output in the one direction, and a configuration in which the input unit and the output unit are displaced from each other in the transverse direction can be achieved.

(Second Modification)

FIG.10is a schematic diagram illustrating a band-pass filter of a second modification. InFIG.10, the order in which a signal propagates resonators is indicated by a one-dot chain line.

A band-pass filter1E of the second modification includes four resonators10E,30E,50E, and70E that are electromagnetically coupled to one another. A signal is input to the resonator30E, and the resonator10E outputs a signal. The resonators50E and70E allow a signal to propagate in the band-pass filter1E. The resonators10E,30E,50E, and70E are configured in a manner similar to the resonators10C,30C,50, and70of the fourth embodiment. However, the configurations of the resonators10E,30E,50E, and70E for being electromagnetically coupled to adjacent resonators thereof are different from those of the resonators10C,30C,50, and70(seeFIGS.7A and7B) of the fourth embodiment.

The resonator30E to which a signal is input and the resonator10E that outputs a signal are arranged in the transverse direction (a direction crossing the axial direction of conductor pins). The two resonators50E and70E that propagate a signal in the band-pass filter1E are arranged in the transverse direction (the direction crossing the axial direction of the conductor pins). In addition, the resonators10E and50E are arranged in the vertical direction (the axial direction of the conductor pins), and the resonators30E and70E are arranged in the vertical direction (the axial direction of the conductor pins). A signal input unit (the connection pad31p(seeFIGS.7A and7B) or an end portion of the conductor pin31(seeFIGS.7A and7B)) and a signal output unit (the connection pad11p(seeFIGS.7A and7B) or an end portion of the conductor pin11(seeFIGS.7A and7B)) are arranged on the same side (the lower surface side of the band-pass filter1E).

A dielectric of the resonator30E and a dielectric of the resonator70E are connected to each other through an opening91hthat is positioned between the two resonators30E and70E, which are arranged one above the other, so that a signal propagates from the resonator30E to the resonator70E. A dielectric of the resonator50E and a dielectric of the resonator10E are connected to each other through an opening81hthat is positioned between the two resonators50E and10E, which are another pair of resonators, so that a signal propagates from the resonator50E to the resonator10E. In the two resonators50E and70E, which are arranged in the transverse direction, the space between portions of each first surrounding conductor is set to be large as in the resonators10C and50(seeFIGS.7A and7B) illustrated inFIG.7such that a signal propagates through the space. Similarly, in the two resonators10E and30E, which are arranged in the transverse direction and to and from which a signal is input and output, the space between portions of each first surrounding conductor may be set to be large such that a signal propagates through the space. In this case, a signal propagates along a propagation path that is indicated by a dashed line in addition to a propagation path that is indicated by a one-dot chain line.

In the band-pass filter1E, the resonators10E and30E correspond to an example of a “first pair of resonators that are arranged a direction crossing the axis direction” and “specific resonators” according to the present disclosure, and the resonators50E and70E correspond to an example of a “second pair of resonators that are arranged a direction crossing the axis direction” and “non-specific resonators” according to the present disclosure.

According to the band-pass filter1E of the second modification, by causing a signal to propagate to three or more resonators, for example, while a signal pass band is widened to a predetermined width, a desired filter characteristic such as a characteristic that the transmittance sharply drops at a boundary of the pass band can be easily achieved. The above-arrangement of the four resonators10E,30E,50E, and70E can reduce the surface area of the band-pass filter1E when viewed in the height direction compared with the configuration in which all the four resonators are arranged in the transverse direction. In addition, since the signal input unit and the signal output unit are arranged on the same side, a surface mount device can be obtained.

The embodiments of the present disclosure have been described above. However, the present invention is not limited to the above-described embodiments. For example, in the first to fourth embodiments and the first and second modifications, the case has been described in which the resonator on the upper side and the resonator on the lower side or the two resonators arranged in the transverse direction have a symmetrical configuration. However, the band-pass filter of the present disclosure may be configured by combining one of the first resonators10(seeFIG.2),10A (seeFIG.5), and10B (seeFIG.6) of the first to third embodiments and one of the second resonators30(seeFIG.2),30A (seeFIG.5), and30B (seeFIG.6) of the first to third embodiments, the one first resonator and the one second resonator having different configurations. In addition, the band-pass filter of the present disclosure may be configured by combining a resonator that includes the first intermediate conductors15(seeFIG.2),15A (seeFIG.5), and15B (seeFIG.6) or the second intermediate conductors35(seeFIG.2),35A (seeFIG.5), and35B (seeFIG.6) of the first to third embodiments and a resonator that does not include these intermediate conductors. Furthermore, in the case where the band-pass filter of the present disclosure is configured by combining three or more resonators, as long as a structure is employed in which at least one of the input resonator or the output resonator includes an intermediate conductor that transversely extends from a conductor pin and that is connected to the first surrounding conductor or the second surrounding conductor, any other resonators such as different types of resonators may be used as the other resonators. Other details described in the embodiments can be suitably changed within the scope of the invention.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to a band-pass filter.

REFERENCE SIGNS LIST

1,1A to1E band-pass filter10,10A,10B,10D first resonator (specific resonator)30,30A,30B,30D second resonator (specific resonator)11,31conductor pin11t,31tsecond end portion12,32first surrounding conductor13,33dielectric14,21,34second surrounding conductor14h,21h,34hopening15,15A,15B first intermediate conductor16B connection pin35,35A,35B second intermediate conductor36B connection pin10C,30C,10E,30E resonator (specific resonator)50,70,50E,70E resonator (non-specific resonator)51,71conductor pin52,72first surrounding conductor53,73dielectric54,61,74second surrounding conductor61h,81h,91hopening