JP6297237B1 - Resonator, filter and filter bank - Google Patents

Abstract

The ground conductor (3) is disposed on one surface of the flat dielectric substrate (4). A line-shaped conductor (1) is provided on the other surface of the dielectric substrate (4) so as to face the ground conductor (3). A floating conductor (2) is provided between the line conductor (1) and the ground conductor (3). The line-shaped conductor (1) has a bent portion (11) having a length of about ½ wavelength at the operating frequency and a linear distance between both ends thereof being 1/8 wavelength or less at the operating frequency. The floating conductor (2) is configured such that the length in the direction parallel to the longitudinal direction of the line-shaped conductor (1) is about ¼ wavelength at the operating frequency.

Description

  The present invention relates to a resonator mainly used in a high frequency band and a high frequency filter using the resonator, and more particularly to a configuration of a planar filter using a strip conductor formed on a dielectric substrate.

In recent years, planar filters using strip lines formed on dielectric substrates are often used as microwave and millimeter wave band filters because of the low loss of substrate material and low cost manufacturing. In particular, a planar filter in which a plurality of resonators composed of strip conductors are electromagnetically coupled to each other is often used.
The planar filter as described above is configured using, for example, a plurality of half-wavelength resonators in which both ends of the line are opened or short-circuited. Therefore, in determining the size and characteristics of the entire filter, the size per resonator and its electrical characteristics are greatly affected. Therefore, in order to realize a reduction in the size of the filter, a reduction in loss, and a broadening of the stop band, a resonator having a small size, a low loss and good spurious characteristics is required. As a resonator satisfying such conditions, for example, a stepped impedance (hereinafter referred to as SI) resonator in which an impedance step is provided in a part of a line, or a hairpin in which a bent part is provided in a line and open ends are brought close to each other There is a type 1/2 wavelength resonator. Among these, the SI hairpin type ½ wavelength resonator has excellent spurious characteristics and has attracted attention as a small resonator (for example, see Non-Patent Document 1).

M. Sagawa, M. Makimoto and S. Yamashita, “Geometrical structures and fundamental characteristics of microwave stepped-impedance resonators,” IEEE Transactions on Microwave Theory and Techniques, vol. 45, no. 7, pp. 1078-1085, July 1997 .

  However, in the SI hairpin type 1/2 wavelength resonator, in order to improve spurious characteristics, the line width at the open end of the line is increased, the line width at the center at both ends of the line is decreased, and between the open ends. It is necessary to reduce the distance. Therefore, in order to realize a resonator having excellent spurious characteristics, it is necessary to make both ends of the line very large. As a result, it is difficult to reduce the size of the resonator. Further, since the open ends are coupled to each other through a very small gap, there is a problem that the resonance frequency of the designed resonator is likely to fluctuate due to a processing error such as a line etching error.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a resonator, a filter, and a filter bank that are small and have excellent spurious characteristics and have reduced characteristic variations due to processing errors. .

The resonator according to the present invention has a flat dielectric substrate, a ground conductor arranged on at least one of the one surface and the other surface of the dielectric substrate, and a length of about 1 at the operating frequency. / 2 having an odd multiple of two wavelengths and having a bent portion symmetrically with respect to the structural symmetry plane including the intermediate point so that the linear distance between both ends thereof is 1/8 wavelength or less at the operating frequency, and the dielectric A line-shaped conductor disposed so as to face the ground conductor through the substrate , a length of about ¼ wavelength or less at the operating frequency, and provided on a dielectric substrate between the line-shaped conductor and the ground conductor The floating conductor is arranged so as to cross the plane of symmetry of the line-shaped conductor.

In the resonator according to the present invention , a floating conductor having a length of about ¼ wavelength or less at an operating frequency is provided between the line-shaped conductor and the ground conductor so as to cross the structural symmetry plane of the line-shaped conductor. . As a result, it is possible to reduce the size, improve the spurious characteristics, and reduce characteristic variations due to processing errors.

1A is a plan view of the resonator according to the first embodiment of the present invention, and FIG. 1B is a cross-sectional view. It is explanatory drawing which shows the analysis result of the frequency characteristic of the resonator by Embodiment 1 of this invention. 3A is an exploded perspective view when the resonator according to the first embodiment of the present invention is realized by a stripline structure, and FIG. 3B is a cross-sectional view. 4A is a plan view when the resonator according to the first embodiment of the present invention is realized by a suspended line structure, and FIG. 4B is a cross-sectional view. FIG. 5A is a plan view showing a resonator according to the second embodiment of the present invention, and FIG. 5B is a cross-sectional view. 6A is a plan view showing a resonator according to the third embodiment of the present invention, and FIG. 6B is a cross-sectional view. FIG. 7A is a plan view when the resonator according to the third embodiment of the present invention is realized by a suspended line structure, and FIG. 7B is a cross-sectional view. 8A is a plan view showing a resonator according to the fourth embodiment of the present invention, and FIG. 8B is a cross-sectional view.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1A is a plan view of the resonator according to the present embodiment, and FIG. 1B is a cross-sectional view.
The resonator shown in FIGS. 1A and 1B is a resonator having a microstrip line structure, which is a dielectric substrate 4, a ground conductor 3, and a line-shaped conductor 1 having a length of about ½ wavelength at an operating frequency. And the floating conductor 2 whose length in the direction parallel to the longitudinal direction of the line-shaped conductor 1 at the operating frequency is ¼ wavelength or less. The line-shaped conductor 1 has a structure that is bent so that the linear distance between both ends thereof is a distance of 1/8 wavelength or less at the operating frequency. A bent portion 11 in the figure is a bent portion in the line-shaped conductor 1. The line-shaped conductor 1 is formed in the same plane XY (the vertical direction in the drawing is the X direction and the horizontal direction in the drawing is the Y direction) and is symmetrical with respect to the plane XZ perpendicular to the plane XY. . Further, the ground conductor 3 is disposed on one surface of the dielectric substrate 4, and the line-shaped conductor 1 is disposed on the other surface. The floating conductor 2 is disposed inside the dielectric substrate 4 between the ground conductor 3 and the line-shaped conductor 1 and is disposed so as to vertically penetrate the structural symmetry plane XZ of the line-shaped conductor 1. Further, the floating conductor 2 is disposed at a position covering both ends of the line-shaped conductor 1 on the plane XY.

Next, the operation of the resonator according to the first embodiment will be described.
In the resonator according to the first embodiment, basically, a standing wave is generated by reflection of an electromagnetic field at the end of the resonator as in the case of a normal open-ended 1/2 wavelength resonator, and the total length of the resonator is 1. It operates as a resonator at a frequency of / 2 wavelength or an integral multiple thereof. In addition, the half-waves with open ends that are often partially bent or curved are called hairpin resonators, split ring resonators, and the like.

In such a resonator, the resonance mode when the total length of the line-shaped conductor 1 is ½ wavelength is called a fundamental wave. Further, when n is an integer of 2 or more, resonance in which the total length of the line-shaped conductor has an n / 2 wavelength is called an nth-order harmonic.
In particular, since the total length of the line-shaped conductor 1 is ½ wavelength in the fundamental wave, the high-frequency current flowing through the surface of the line-shaped conductor 1 has an antiphase with respect to the structural symmetry plane XZ of the line-shaped conductor 1. At this time, the electric field is asymmetric with respect to the structural symmetry plane XZ of the line-shaped conductor 1, and has the same electromagnetic field distribution as that in the case of the virtual electrical wall on the structural symmetry plane XZ. Therefore, it can be considered that the floating conductor 2 is short-circuited on the structural symmetry plane XZ. As a result, between the line-shaped conductor 1 and the floating conductor 2, there is a grounded conductor in the vicinity of the line-shaped conductor 1, so that the electric field strength increases. As a result, the capacitance of the resonator increases, and the resonance frequency of the fundamental wave can be greatly reduced.

  On the other hand, since the total length of the line-shaped conductor 1 is one wavelength at the second harmonic, the high-frequency current flowing through the surface of the line-shaped conductor 1 is in phase with the structural symmetry plane XZ of the line-shaped conductor 1. At this time, it is equivalent if there is a virtual magnetic wall on the structural symmetry plane XZ. Therefore, it can be considered that the floating conductor 2 is open in the structural symmetry plane XZ. Therefore, the floating conductor 2 does not operate as a ground conductor, and the electric field strength does not change greatly compared to the case without the floating conductor 2, so that the resonance frequency of the second harmonic is approximately equal to that without the floating conductor 2. .

  Thus, the resonant frequency can be lowered by utilizing the fact that the floating conductor 2 operates as a ground conductor in the resonance mode. In particular, in a half-wave resonator with both ends open, the resonance frequency of the resonance mode in which the total length of the line-shaped conductor 1 is an odd multiple of a half wavelength is lowered, and the resonance frequency of the resonance mode in which the entire length is an even multiple is not significantly changed.

  FIG. 2 shows the analysis results of the frequency characteristics of the resonator according to the first embodiment and the conventional SI hairpin type ½ wavelength resonator. In the figure, the solid line is the frequency characteristic of the resonator of the first embodiment, and the broken line is the frequency characteristic of the conventional SI hairpin type ½ wavelength resonator. Here, both are designed so that the frequency of the fundamental wave is 1 at the normalized frequency. At this time, focusing on the frequency of the second harmonic, the conventional SI hairpin type ½ wavelength resonator is about 2.2, whereas the resonator of the first embodiment is 2.5. From this, it can be seen that the frequency of the second harmonic is shifted to a higher frequency, and the resonator of the first embodiment has excellent spurious characteristics. At this time, the ratio of the area occupied by the resonator is 0.95 for the resonator of the first embodiment, assuming that the conventional SI hairpin type ½ wavelength resonator is 1. This also shows that the resonator has been downsized.

  As described above, the resonator of the present embodiment can realize the same resonance frequency while being smaller than the structure of a conventional resonator. Moreover, since the frequency of the fundamental wave is lowered and the resonance frequency of the second harmonic does not change, the spurious characteristics can be improved.

  In the conventional resonator, both ends of the line-shaped conductor 1 are brought close to each other with a very small gap, thereby increasing the electric field strength at the end of the resonator and improving the spurious characteristics. However, the resonator according to the present embodiment can increase the electric field strength at the end of the resonator without reducing the gap between the both ends of the line-shaped conductor 1 by using the floating conductor 2, and has excellent spurious characteristics. The characteristics can be realized. Therefore, the resonance frequency is unlikely to fluctuate due to processing errors when forming the line-shaped conductor 1.

  Therefore, by forming a planar filter using the resonator according to the present embodiment, it is possible to realize a small filter having excellent spurious characteristics. At the same time, a filter resistant to manufacturing errors can be realized, and the yield of the filter can be improved.

  In the configuration shown in FIG. 1, the resonator is realized by a microstrip line structure. However, as shown in FIG. 3, ground conductors 3 are provided on two opposing outer surfaces of a plurality of dielectric substrates 4, respectively. A strip line structure in which the line-shaped conductor 1 and the floating conductor 2 are arranged on the inner layer of the substrate 4 may be used. Here, FIG. 3A is an exploded perspective view of the resonator, and FIG. 3B is a sectional view. That is, the resonator shown in FIG. 3 is provided with a plurality of dielectric substrates 4 and ground conductors 3, and a plurality of ground conductors 3 are provided opposite to each other with the plurality of dielectric substrates 4 interposed therebetween. Further, the line-shaped conductor 1 is provided between the plurality of dielectric substrates 4, and the floating conductor 2 is provided between the dielectric substrate 4 and the ground conductor 3.

  Further, as shown in FIG. 4, the line-shaped conductor 1 and the floating conductor 2 are provided on the two opposing surfaces of the dielectric substrate 4, respectively, and the lower surface of the dielectric substrate 4 provided with the floating conductor 2 is grounded. It is good also as a suspended line structure which has arrange | positioned the metal housing | casing 6 instead of the conductor 3. FIG. 4A is a plan view of the resonator, and FIG. 4B is a cross-sectional view.

  In the above example, the case where the line-shaped conductor 1 has a symmetric structure has been described in order to simplify the description. However, the present invention is not limited to the case where the line-shaped conductor 1 has a symmetric structure. There may be. Further, the line-shaped conductor 1 only needs to be an odd multiple of about ½ wavelength at the operating frequency. Furthermore, in the above example, the number of the bent portions 11 is one, but there may be a plurality of them.

  As described above, according to the resonator of the first embodiment, a flat dielectric substrate, and a ground conductor disposed on at least one of the one surface and the other surface of the dielectric substrate, A bending portion for making the linear distance of both ends thereof an odd multiple of 1/8 wavelength or less at the operating frequency, the length being an odd multiple of about ½ wavelength at the operating frequency, and a dielectric substrate Through which a line-shaped conductor arranged so as to face the ground conductor and a floating conductor provided on the dielectric substrate between the line-shaped conductor and the ground conductor can be miniaturized and improved spurious characteristics. And variation in characteristics due to processing errors can be reduced.

  Further, according to the resonator of the first embodiment, the ground conductor is disposed on one surface of the dielectric substrate, the line conductor is disposed on the other surface, and the line conductor is long at the operating frequency. And the length of the floating conductor in the direction parallel to the longitudinal direction of the line-shaped conductor at the operating frequency is about ¼ wavelength. As a container, it is small and has excellent spurious characteristics, and can reduce variations in characteristics due to processing errors.

  In addition, according to the resonator of the first embodiment, since the metal casing is used instead of the ground conductor, and the metal casing and the floating conductor are arranged in a non-contact manner to form the suspended line structure, the resonance of the suspended line structure is achieved. As a container, it is small and has excellent spurious characteristics, and can reduce variations in characteristics due to processing errors.

  Further, according to the resonator of the first embodiment, a plurality of dielectric substrates and ground conductors are provided, and a plurality of ground conductors are provided to face each other via a plurality of dielectric substrates, and between the plurality of dielectric substrates. Since the strip-line structure is provided with a line-shaped conductor, it has a small and excellent spurious characteristic as a resonator of the strip-line structure, and can reduce characteristic variations due to processing errors.

Embodiment 2. FIG.
The second embodiment is an example in which the line-shaped conductor 1 is composed of a plurality of conductors having different line widths.
5A is a plan view of the resonator according to the second embodiment, and FIG. 5B is a cross-sectional view thereof.
The illustrated resonator is a resonator having a microstrip line structure, and includes a dielectric substrate 4, a ground conductor 3, a line-shaped conductor 1 having a length of about ½ wavelength at an operating frequency, and an operating frequency. It is comprised by the floating conductor 2 whose length is 1/4 wavelength or less. Here, the line-shaped conductor 1 is composed of conductors 1a and 1b having a total length of about ８ wavelength and a conductor 1c having a total length of about ¼ wavelength. The conductors 1a and 1b are connected to both ends of the conductor 1c, respectively. The The conductor 1a and the conductor 1b have the same line width, and the conductor 1c has a smaller line width than the conductor 1a and the conductor 1b. Moreover, the line-shaped conductor 1 has the bending part 11 so that the linear distance between the both ends may become a 1/8 wavelength or less distance in an operating frequency. The line-shaped conductor 1 is formed in the same plane XY and is structurally symmetric with respect to a plane XZ perpendicular to the plane XY. Since the configuration other than this is the same as the configuration of the first embodiment shown in FIGS. 1A and 1B, the same reference numerals are given to corresponding portions, and the description thereof is omitted.

Hereinafter, the operation of the second embodiment will be described. Note that description of the same contents as those in Embodiment 1 is omitted.
First, the operation in the fundamental wave of the resonator of the second embodiment will be described. In the fundamental wave, the total length of the line-shaped conductor 1 is ½ wavelength, and the high-frequency current flowing through the surface of the line-shaped conductor 1 has an opposite phase with respect to the structural symmetry plane XZ of the line-shaped conductor 1. Therefore, as described in the first embodiment, the floating conductor 2 is virtually shorted on the structural symmetry plane XZ. At this time, since the electric field concentrates between the conductors 1a and 1b and the floating conductor 2, the larger the line width of the conductors 1a and 1b, the larger the capacitance of the resonator and the lower the resonance frequency.

On the other hand, since the total length of the line-shaped conductor 1 is one wavelength at the second harmonic, the high-frequency current flowing through the surface of the line-shaped conductor 1 is in phase with the structural symmetry plane XZ of the line-shaped conductor 1, and at this time, the structure This is equivalent to a virtual magnetic wall on the symmetry plane XZ. The high-frequency current in the line-shaped conductor 1 is maximum at a position where the wavelength is about ¼ wavelength from the end of the line-shaped conductor 1, that is, in the vicinity of the connection portion between the conductors 1a and 1c and in the vicinity of the connection portion between the conductors 1b and 1c. It becomes. Therefore, the larger the line width of the conductor 1a and the conductor 1b, the smaller the current density, the lower the inductance of the resonator, and the higher the resonant frequency.
Therefore, the resonator of the second embodiment can further improve the spurious characteristics in addition to the effect of the resonator of the first embodiment.

In the resonator according to the second embodiment, the gap between both ends of the line-shaped conductor 1 is smaller than that of the configuration according to the first embodiment. However, since the floating conductor 2 provides a great spurious improvement effect, The spurious characteristic equivalent to that of the conventional resonator can be realized without using such a small gap. Therefore, the resonance frequency is unlikely to fluctuate due to processing errors when forming the line-shaped conductor 1.
Therefore, by forming a planar filter using the resonator according to the second embodiment, it is possible to realize a small filter with excellent spurious characteristics. At the same time, a filter that is resistant to manufacturing errors can be realized, and the yield of the filter can be improved.

In the above example, the resonator is realized by a microstrip line structure, but it may be a strip line structure or a suspended line structure as in the first embodiment.
In the second embodiment, the case where the line-shaped conductor 1 has a symmetric structure has been described for the sake of simplicity. However, the present invention is not limited to the case where the line-shaped conductor 1 has a symmetric structure, but an asymmetric structure. It may be. The line lengths of the conductors 1a, 1b, and 1c in the second embodiment are merely examples, and do not limit the scope of the second embodiment.
Further, in the above example, the conductors 1a, 1b, and 1c are configured so that the line width gradually increases from the intermediate part of the line-shaped conductor 1 to both ends, but from the intermediate part of the line-shaped conductor 1 to both ends. The shape may be a reverse taper shape.

  As described above, according to the resonator of the second embodiment, the line-shaped conductor is composed of a plurality of conductors having different line widths, and the line width gradually increases from the middle part to both ends of the line-shaped conductor. Since the shape is increased, the spurious characteristics can be further improved in addition to the effects of the first embodiment.

  Further, according to the resonator of the second embodiment, since the line-shaped conductor has a reverse taper shape from the intermediate portion of the line-shaped conductor toward both ends, in addition to the effects of the first embodiment, Further spurious characteristics can be improved.

Embodiment 3 FIG.
The third embodiment is an example in which the floating conductor 2 is provided on the dielectric substrate 4 so as to face the ground conductor 3 and the line-shaped conductor 1 is disposed inside the dielectric substrate 4.
6A is a plan view of the resonator according to the third embodiment, and FIG. 6B is a sectional view thereof.
The illustrated resonator is a resonator having a microstrip line structure, and includes a dielectric substrate 4, a ground conductor 3, a line-shaped conductor 1 having a length of about ½ wavelength at an operating frequency, and an operating frequency. It is constituted by the floating conductor 2 whose length in the direction parallel to the longitudinal direction of the line-shaped conductor 1 is ¼ wavelength or less. Moreover, the line-shaped conductor 1 has the bending part 11 for the linear distance between the both ends to become a distance below 1/8 wavelength in an operating frequency. Furthermore, the line-shaped conductor 1 is structurally symmetric with respect to a plane XZ formed in the same plane XY and perpendicular to the plane XY. On the other hand, the ground conductor 3 is disposed on one surface of the dielectric substrate 4, and the line conductor 1 is disposed in the inner layer of the dielectric substrate 4 so as to face the ground conductor 3. The floating conductor 2 is disposed on the other surface of the dielectric substrate 4 so as to penetrate the structural symmetry plane XZ of the line-shaped conductor 1 vertically.

Next, the operation of the third embodiment will be described. Note that description of the same contents as those in Embodiment 1 is omitted.
First, the operation in the fundamental wave of the resonator of the second embodiment will be described. In the fundamental wave, the total length of the line-shaped conductor 1 is ½ wavelength, and the high-frequency current flowing through the surface of the line-shaped conductor 1 has an opposite phase with respect to the structural symmetry plane XZ of the line-shaped conductor 1. Therefore, as described in the first embodiment, the floating conductor 2 is virtually shorted on the structural symmetry plane XZ. At this time, since the end of the line-shaped conductor 1 is sandwiched between the floating conductor 2 and the ground conductor 3, between the line-shaped conductor 1 and the floating conductor 2 and between the line-shaped conductor 1 and the ground conductor 3. , The electric field concentrates. Therefore, as compared with the configuration of the first embodiment, if the distance between the line-shaped conductor 1 and the floating conductor 2 is approximately the same, the electric field strength is further increased. Therefore, it is possible to further reduce the size while realizing a resonance frequency similar to that of the first embodiment.

On the other hand, since the total length of the line-shaped conductor 1 is one wavelength at the second harmonic, the high-frequency current flowing through the surface of the line-shaped conductor 1 is in phase with the structural symmetry plane XZ of the line-shaped conductor 1, and at this time, the structure It is equivalent if there is a virtual magnetic wall on the symmetry plane XZ. Therefore, the floating conductor 2 does not operate as a ground conductor, and the resonance frequency is approximately the same as that in the case where the floating conductor 2 is not provided.
Therefore, the resonator according to the third embodiment can realize more excellent spurious characteristics while having the effect of the resonator according to the first embodiment.

  In the above example, the resonator is realized by the microstrip line structure. However, as shown in FIGS. 7A and 7B, the line-shaped conductor 1 and the floating conductor 2 are provided on the two opposing surfaces of the dielectric substrate 4, respectively. Moreover, it is good also as a suspended line structure which has arrange | positioned the metal housing | casing 6 instead of the ground conductor 3, etc. in the one surface of the dielectric substrate 4 in which the line-shaped conductor 1 was provided. That is, this configuration is equivalent to the positional relationship between the line-shaped conductor 1 and the floating conductor 2 being reversed in the configuration shown in FIGS. 4A and 4B of the first embodiment.

  In the third embodiment, the case where the line-shaped conductor 1 has a symmetric structure has been described for the sake of simplification, but the present invention is not limited to the case where the line-shaped conductor 1 has a symmetric structure. There may be.

  As described above, according to the resonator of the third embodiment, the length of the flat dielectric substrate, the ground conductor disposed on one surface of the dielectric substrate, and the length at the operating frequency is about ½. A line-shaped conductor having a bent portion for being a wavelength and having a linear distance at both ends of a distance of 1/8 wavelength or less at the operating frequency, and a length of about 1/4 wavelength or less at the operating frequency, In addition, since the floating conductor is disposed on the other surface of the dielectric substrate, and the line-shaped conductor is disposed between the ground conductor and the floating conductor so as to face the ground conductor, the effect of the first embodiment is achieved. In addition, further downsizing can be achieved.

  Further, according to the resonator of the third embodiment, since the metal casing is replaced with the ground conductor and the metal casing and the line-shaped conductor are arranged in a non-contact manner to form the suspended line structure, the resonance of the suspended line structure is achieved. As a container, further downsizing can be achieved.

Embodiment 4 FIG.
The fourth embodiment is an example in which the floating conductor is composed of a plurality of floating conductor pieces whose long sides are 1/16 wavelength or less.
8A is a plan view of the resonator according to the fourth embodiment, and FIG. 8B is a sectional view thereof.
The illustrated resonator is a resonator having a microstrip line structure, and includes a dielectric substrate 4, a ground conductor 3, a line-shaped conductor 1 having a length of about ½ wavelength at an operating frequency, and an operating frequency. The floating conductor 5 is composed of a group of floating conductor pieces consisting of a plurality of floating conductor pieces 5a to 5i having a long side of 1/16 wavelength or less. The line-shaped conductor 1 has a bent portion 11 for the linear distance between the both end portions to be a distance of 1/8 wavelength or less at the operating frequency. The line-shaped conductor 1 is structurally symmetric with respect to a plane XZ formed in the same plane XY and perpendicular to the plane XY. The ground conductor 3 is disposed on one surface of the dielectric substrate 4 and the line conductor 1 is disposed on the other surface. The floating conductor 5 is disposed inside the dielectric substrate 4 between the ground conductor 3 and the line-shaped conductor 1 and is disposed so as to vertically penetrate the structural symmetry plane XZ of the line-shaped conductor 1. At this time, the floating conductor pieces 5a to 5i are provided with an interval of 1/32 wavelength or less.

In the first to third embodiments, the second harmonic of the line conductor 1 is regarded as the first spurious resonance, and the ratio of the frequency of the fundamental wave and the first spurious resonance is increased. . However, in Embodiments 1 to 3, when the long side of the floating conductor 2 has about ½ wavelength, a standing wave is generated on the floating conductor 2 and this operates as a resonator. Therefore, in order to improve the spurious characteristics, it is necessary to design the dimensions so that the floating conductor 2 does not operate as a resonator. For example, the fundamental wave of the floating conductor 2 can be made higher by reducing the size of the floating conductor 2. However, when the floating conductor 2 is made smaller, the area where the electric field between the line-shaped conductor 1 and the floating conductor 2 is concentrated in the fundamental wave of the line-shaped conductor 1 is reduced, and the resonance frequency is increased. . As described above, in the resonators according to the first to third embodiments, the resonance frequency of the fundamental wave of the line conductor 1 is lowered, and at the same time, the resonance frequency of the fundamental wave of the floating conductor 2 is increased. Was left as an issue.
The resonator according to the fourth embodiment can solve the above-described problems and realize more excellent spurious characteristics.

Next, the operation of the fourth embodiment will be described. Note that description of the same contents as those in Embodiment 1 is omitted.
First, the operation in the fundamental wave of the resonator of the fourth embodiment will be described. In the fundamental wave, the total length of the line-shaped conductor 1 is ½ wavelength, and the high-frequency current flowing through the surface of the line-shaped conductor 1 has an opposite phase with respect to the structural symmetry plane XZ of the line-shaped conductor 1. Therefore, as described in the first embodiment, the floating conductor 5 is virtually short-circuited on the structural symmetry plane XZ. If the space | interval of the floating conductor pieces 5a-5i in the floating conductor 5 is very small compared with the frequency at this time, the electric field density between the line conductor 1 and the floating conductor pieces 5a-5i will not change a lot. Therefore, compared with the resonator structure of the first embodiment, the resonator of the fourth embodiment has an equivalent resonance frequency.

On the other hand, since the total length of the line-shaped conductor 1 is one wavelength at the second harmonic, the high-frequency current flowing through the surface of the line-shaped conductor 1 is in phase with the structural symmetry plane XZ of the line-shaped conductor 1, and at this time, the structure It is equivalent if there is a virtual magnetic wall on the symmetry plane XZ. Therefore, the floating conductor 5 does not operate as a ground conductor, and the resonance frequency is approximately the same as that in the case where the floating conductor 5 is not provided. Moreover, since the floating conductor pieces 5a to 5i each have a long side of 1/16 wavelength or less, the fundamental wave generated by the floating conductor pieces 5a to 5i is at least four times the resonance frequency of the fundamental wave of the line-shaped conductor 1. Occurs at frequency.
Therefore, the resonator according to the fourth embodiment can move unnecessary resonance due to the floating conductor 5 to the high frequency band, and can realize more excellent spurious characteristics.

In the above example, the resonator is realized by a microstrip line structure, but it may be a strip line structure or a suspended line structure as in the first embodiment.
In the fourth embodiment, the case where the line-shaped conductor 1 has a symmetric structure has been described in order to simplify the description. However, the present invention is not limited to the case where the line-shaped conductor 1 has a symmetric structure, but an asymmetric structure. It may be. Note that the dimensions of the floating conductor pieces 5a to 5i in the fourth embodiment are merely examples, and do not limit the scope of the fourth embodiment.

  As described above, according to the resonator of the fourth embodiment, the floating conductor is made up of a plurality of floating conductor pieces whose long sides are 1/16 wavelength or less, so in addition to the effects of the first embodiment. Thus, spurious characteristics can be further improved.

  In the first to fourth embodiments, the resonator has been described. However, the input / output means for electrically connecting to one or a plurality of resonators using one or a plurality of the resonators of any of the embodiments is provided. It may be provided and configured as a filter. In this way, it is possible to realize a filter that is more resistant to etching errors than conventional ones.

  Furthermore, a plurality of filters may be used, and a filter bank may be configured by connecting the dielectric substrates of these filters in the same plane. In this way, it can contribute to the improvement of the manufacturing yield of the filter.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  As described above, the resonator according to the present invention relates to the configuration of the SI hairpin type ½ wavelength resonator and is suitable for use in a microwave or millimeter wave band filter.

  DESCRIPTION OF SYMBOLS 1 Line-shaped conductor, 1a, 1b, 1c conductor, 2,5 Floating conductor, 3 Ground conductor, 4 Dielectric substrate, 5a-5i Small piece of floating conductor, 6 Metal housing, 11 Bending part.

Claims (11)

A flat dielectric substrate;
A ground conductor disposed on at least one of the one surface and the other surface of the dielectric substrate;
Bending part symmetrically with respect to the structural symmetry plane including the intermediate point so that the length at the operating frequency is an odd multiple of about 1/2 wavelength and the linear distance between both ends thereof is 1/8 wavelength or less at the operating frequency. And a line-shaped conductor disposed to face the ground conductor via the dielectric substrate, and
A floating conductor having a length of about ¼ wavelength or less at an operating frequency and provided on a dielectric substrate between the line-shaped conductor and the ground conductor;
A resonator in which the floating conductor is disposed so as to cross a structural symmetry plane of the line-shaped conductor.   The ground conductor is disposed on one surface of the dielectric substrate, the line conductor is disposed on the other surface, and the line conductor has a length of about ½ wavelength at an operating frequency. The resonator according to claim 1, wherein the floating conductor has a length in a direction parallel to a longitudinal direction of the line-shaped conductor at an operating frequency of about ¼ wavelength.   3. A resonator according to claim 2, wherein the ground conductor is replaced with a metal case, and the metal case and the floating conductor are arranged in a non-contact manner to form a suspended line structure.   A plurality of the dielectric substrate and the ground conductor are provided, the plurality of ground conductors are provided to face each other via the plurality of dielectric substrates, and the line-shaped conductor is provided between the plurality of dielectric substrates. 2. The resonator according to claim 1, wherein the resonator has a stripline structure.   The line-shaped conductor is composed of a plurality of conductors having different line widths, and has a shape in which the line width gradually increases from an intermediate portion to both ends of the line-shaped conductor. Resonator.   The resonator according to claim 1, wherein the line-shaped conductor has a reverse taper shape from an intermediate portion of the line-shaped conductor toward both ends. A flat dielectric substrate;
A ground conductor disposed on one surface of the dielectric substrate;
The bending portion is symmetrically formed with respect to the structural symmetry plane including the intermediate point so that the length is about ½ wavelength at the operating frequency and the linear distance between both ends is １ ／ wavelength or less at the operating frequency. A line-shaped conductor having,
A floating conductor having a length of about ¼ wavelength or less at an operating frequency and disposed on the other surface of the dielectric substrate,
The floating conductor is disposed so as to cross a structural symmetry plane of the line-shaped conductor, and the line-shaped conductor is disposed between the ground conductor and the floating conductor so as to face the ground conductor. Resonator.   8. A resonator according to claim 7, wherein the ground conductor is replaced with a metal casing, and the metal casing and the line conductor are arranged in a non-contact manner to form a suspended line structure.   The resonator according to claim 1, wherein the floating conductor is composed of a plurality of floating conductor pieces whose long sides are 1/16 wavelength or less.   A filter comprising input / output means for electrically coupling to the resonator according to claim 1.   A filter bank comprising a plurality of the filters according to claim 10, wherein the dielectric substrates in each of the filters are integrated in the same plane.

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