JP4778011B2 - High frequency filter - Google Patents

Description

  The present invention relates to a high frequency filter having a resonance pattern of a microstripline or stripline structure.

  FIG. 13A shows a plan view of the high-frequency filter described in Patent Document 1 below, and FIG. 13B shows a cross-sectional view taken along one-dot chain line 11B-11B in FIG. 13A.

  On the main surface of the dielectric substrate 101, a resonance pattern 102, an input port 103, and an output port 104 are formed. The planar shape of the resonance pattern 102 is circular. The input port 103 and the output port 104 are electromagnetically coupled to the resonance pattern 102 at two points on the outer periphery of the resonance pattern 102 that form a central angle of 90 °. A ground film 105 is formed on the back surface of the dielectric substrate 101. The resonance pattern 102, the ground film 105, and the dielectric substrate 101 constitute a microstrip line.

  Another dielectric substrate 110 is disposed on the resonance pattern 102. A conductor pattern 111 is formed on the surface of the dielectric substrate 110. The conductor pattern 111 is disposed at a position that overlaps the center point of an arc having a central angle of 270 ° with the coupling position between the input port 103 and the resonance pattern 102 and the coupling position between the output port 104 and the resonance pattern 102 as both ends. Yes. The planar shape of the conductor pattern 111 is, for example, a circle, and its diameter is ¼ or less of the effective wavelength of the high-frequency signal propagating through the microstrip line.

  When the conductor pattern 111 is electromagnetically coupled to the resonance pattern 102, the degeneration of the two electromagnetic field modes orthogonal to each other of the resonance pattern 102 is solved, and the resonance frequency is separated. Thereby, the high frequency device shown in FIG. 13A functions as a dual mode filter.

  The disc-type resonance pattern shown in FIGS. 13A and 13B is less likely to cause current concentration at a specific location than the hairpin-type resonance pattern and the straight-line-type resonance pattern. Further, even when compared with a disk pattern in which a notch is provided on a part of a circular outer periphery, current concentration is less likely to occur at a specific location. For this reason, power tolerance is high and application to a transmission filter is expected.

JP 2006-115416 A

  In the high frequency filter shown in FIGS. 13A and 13B, due to an air gap generated between the resonant pattern 102 and the dielectric substrate 110 disposed thereon, a positional deviation between the resonant pattern 102 and the conductor pattern 111, etc. Filter characteristics deviate from design values.

  An object of the present invention is to provide a high-frequency filter in which current concentration at a specific portion of a resonance pattern is unlikely to occur and an actual filter characteristic is unlikely to deviate from a design value.

According to one aspect of the invention,
A substrate made of a dielectric material;
A first resonance pattern having a circular planar shape formed of a conductive material on the main surface of the substrate;
A first electromagnetically coupled to the first resonance pattern at one intersection of the first imaginary straight line passing through the center of the first resonance pattern and the outer periphery of the first resonance pattern An input port;
A first output port that electromagnetically couples to the first resonance pattern at the other intersection of the first imaginary straight line and the outer periphery of the first resonance pattern;
The first resonance at one intersection of a second imaginary line that passes through the center of the first resonance pattern and is orthogonal to the first imaginary line, and an outer peripheral line of the first resonance pattern. A second input port electromagnetically coupled to the pattern;
A second output port that electromagnetically couples to the first resonance pattern at the other intersection of the second imaginary straight line and the outer periphery of the first resonance pattern;
A first inter-port waveguide for propagating a high-frequency signal output to the first output port to the second input port ;
A high frequency filter having a ground film formed on a surface opposite to the main surface of the substrate is provided.

  By forming the resonance pattern, the input / output port, and the inter-port waveguide on one dielectric substrate, it is possible to prevent the shift of the resonance frequency due to the position shift of the plurality of patterns. Further, since the resonance pattern or the like is formed on one surface of the substrate, the manufacturing efficiency is high, and a more remarkable effect is expected particularly when the resonator is multistaged. Furthermore, since a circular resonance pattern is used, the power durability is high, and nonlinear distortion at the time of high power input is suppressed.

  FIG. 1A shows a cross-sectional view of the high-frequency filter according to the first embodiment, and FIG. 1B shows a flat cross-sectional view taken along one-dot chain line 1B-1B in FIG. A cross-sectional view taken along one-dot chain line 1A-1A in FIG. 1B corresponds to FIG. 1A.

  A dielectric substrate 20 having a resonance pattern 21 and the like formed on the main surface and a ground film 27 formed on the back surface is disposed on the bottom surface of the main body 15A of the package 15. The ground film 27 contacts the bottom surface of the package body 15A.

  The package body 15A is a rectangular parallelepiped container having an upper opening, and the opening is closed with a top plate 15B. The package body 15A and the top plate 15B constitute a package 15 that defines a closed space inside. The package 15 is made of, for example, oxygen-free copper having excellent thermal conductivity and conductivity. In addition to oxygen-free copper, pure aluminum, an aluminum alloy, a copper alloy, or the like may be used. Further, it may be formed of Kovar, Invar, 42 alloy or the like having a thermal contraction rate close to that of the dielectric substrate 20. The package 15 is plated with gold having a thickness of about 2 μm in order to prevent deterioration of electrical characteristics due to surface oxidation.

The dielectric substrate 20 is made of magnesium oxide (MgO) having a (100) crystal plane appearing on the main surface, and its thickness is 0.5 mm. As a material of the dielectric substrate 20, a dielectric material having a high dielectric constant and low loss such as LaAlO ₃ and sapphire may be used.

As shown in FIG. 1B, on the main surface of the dielectric substrate 20, a resonance pattern 21, a first input port 22, a first output port 23, a second input port 24, a second output port 25, and An inter-port waveguide 26 is formed. The resonance pattern 21 in the case of producing a 5 GHz band-pass filter on the dielectric substrate 20 has a circular planar shape with a diameter of 11 mm. At this time, the relationship between the wavelength λr of the high-frequency signal resonating in the resonance pattern 21 and the diameter d of the resonance pattern d is
d = (n / 2) λr (n is a natural number) (1)
It becomes. Here, a frequency corresponding to the wavelength λr when n = 1 is referred to as a “basic resonance frequency”. That is, the signal of the basic resonance frequency of the resonance pattern 21 has a wavelength twice that diameter, that is, 22 mm. The actual resonance wavelength can be determined from the effective dielectric constant of the microstrip line and the electrically measured resonance frequency. Actually, the wavelength of the resonating high-frequency signal is slightly deviated from the resonance wavelength λr obtained by the above equation (1) due to leakage of electromagnetic waves from the edge of the resonance pattern 21 or the like.

  A first imaginary straight line 40 and a second imaginary straight line 41 that pass through the center of the resonance pattern 21 and are orthogonal to each other are defined. The first input port 22 is electromagnetically coupled to the resonance pattern 21 at one intersection of the outer periphery of the resonance pattern 21 and the first imaginary straight line 40, and the first output port 23 is coupled at the other intersection. Are electromagnetically coupled to the resonance pattern 21. The planar shape of each of the first input port 22 and the first output port 23 is a crescent shape having a curvature along the outer periphery of the resonance pattern 21, and is axisymmetric with respect to the first virtual straight line 40.

  The second input port 24 is electromagnetically coupled to the resonance pattern 21 at one intersection of the outer periphery of the resonance pattern 21 and the second virtual straight line 41, and the second output port 25 is coupled at the other intersection. Are electromagnetically coupled to the resonance pattern 21. The planar shape of each of the second input port 24 and the second output port 25 is a crescent shape having a curvature along the outer periphery of the resonance pattern 21, and is axisymmetric with respect to the second virtual straight line 41. Each of these input / output ports 22 to 25 is disposed at a distance of 25 to 100 μm from the edge of the resonance pattern 21.

  An input waveguide 31 is connected to the first input port 22. The input waveguide 31 is disposed along the first virtual straight line 40. An output waveguide 32 is connected to the second output port 25. The output waveguide 32 is disposed along the second virtual straight line 41. The inter-port waveguide 26 connects the first output port 23 and the second input port 24, and propagates the high-frequency signal output to the first output port 23 to the second input port 24.

The resonance pattern 21, the input / output ports 22 to 25, the waveguides 31 and 32, the inter-port waveguide 26, and the ground film 27 are formed of YBa ₂ Cu ₃ O _{6 + x} (hereinafter referred to as “YBCO”). Its thickness is 100-500 nm. In addition to YBCO, these conductive patterns may be formed of an oxide superconducting material that exhibits a superconducting state at a liquid nitrogen temperature. Examples of oxide superconducting materials include R-Ba-Cu-O-based (R is Nb, Ym, Sm, or Ho) material, Bi-Sr-Ca-Cu-O-based material, Pb-Bi-Sr-Ca. -cu-O-based _{material, CuBa p Ca q Cu r O} x based material (1.5 <p <2.5,2.5 <q <3.5,3.5 <r <4.5) or the like Can be mentioned.

  The widths of the input waveguide 31, the output waveguide 32, and the inter-port waveguide 26 are 0.5 mm when formed on the dielectric substrate 20, and the characteristic impedance of the waveguide at this time is 50Ω. . On the surface of each of the input waveguide 31 and the output waveguide 32 near the end far from the resonance pattern 21, an electrode in which a Cr film, a Pd film, and an Au film are stacked in this order is formed. .

  The YBCO film can be formed by, for example, a pulse laser deposition method. Each YBCO pattern on the main surface of dielectric substrate 20 can be formed using a normal photolithography technique. An electrode in which a Cr film, a Pd film, and an Au film are stacked can be formed by vapor deposition and a lift-off method.

  Coaxial input connectors 35 and output connectors 36 are attached to the side wall of the package body 15A. The center conductor of the input connector 35 is connected to the electrode at the end of the input waveguide 31 by an Au wire having a diameter of 25 μm, and the center conductor of the output connector 36 is the electrode at the end of the output waveguide 32 by an Au wire having a diameter of 25 μm. It is connected to the. An Au ribbon or Al wire may be used instead of the Au wire.

  FIG. 2A shows a simulation result of the transmission characteristic (frequency dependence of S parameter of S21) of the high frequency filter according to the first embodiment. The simulation was performed using an electromagnetic simulator made by Sonnet. The horizontal axis represents the frequency in the unit “GHz”, and the vertical axis represents the magnitude of S21 in the unit “dB”. For comparison, the transmission characteristics of the high frequency filter (comparative example) having the resonance pattern shown in FIG. In the high frequency filter according to the comparative example, the input port 22a and the output port 25a are arranged at positions facing each other across the circular resonance pattern 21a.

  As shown in FIG. 2A, S21 of the high frequency filter according to the first embodiment shows a maximum value at a frequency of about 5 GHz. By adopting the configuration of the embodiment, a steeper frequency cutoff characteristic can be obtained as compared with the high-frequency filter of the comparative example shown in FIG. 2B. In particular, in the case of the first embodiment, an attenuation pole appears in the frequency region outside the cutoff frequency, and it can be seen that a steep frequency cutoff characteristic is obtained.

  FIG. 3 shows an actual measurement result of the S parameter of the high frequency filter according to the first embodiment. As the dielectric substrate 20, an MgO substrate having a thickness of (100) crystal plane and having a thickness of 0.5 mm is used, and each pattern on the main surface of the dielectric substrate 20 and the ground film 27 are formed by YBCO. Was 500 nm. The diameter of the resonance pattern 21 was 11 mm, and the distance between each of the input / output ports 22 to 25 and the edge of the resonance pattern 21 was 25 μm. The length of the inter-port waveguide 26 was 12.1 mm. This length extends from the edge of the first output port 23 facing the resonance pattern 21 to the edge of the second input port 24 facing the resonance pattern 21 via the center of the inter-port waveguide 26. It means the length of the route to reach. This high-frequency filter was cooled to a temperature of 65K, the YBCO film was brought into a superconducting state, and S parameters were measured.

  The horizontal axis in FIG. 3 represents the frequency in the unit “GHz”, and the vertical axis represents the magnitude of the S parameter in the unit “dB”. A solid line in the graph indicates S21, that is, a transmission characteristic, and a broken line indicates S11, that is, a reflection characteristic. It can be seen that there is a steep frequency cutoff characteristic equivalent to the simulation result shown in FIG. 2A.

  Unlike the conventional high frequency filter shown in FIGS. 13A and 13B, the first embodiment does not require a plurality of dielectric substrates. For this reason, the filter characteristic does not deviate from the design value due to the positional deviation of the plurality of dielectric substrates.

  FIG. 4 shows simulation results of S parameters of three types of high-frequency filters having different lengths of the inter-port waveguide 26 when the distance between each of the input / output ports 22 to 25 and the edge of the resonance pattern 21 is 75 μm. Indicates. The horizontal axis represents the frequency in the unit “GHz”, and the vertical axis represents the size of the S parameter in the unit “dB”. A one-dot chain line, a solid line, and a broken line in the graph indicate S parameters of the high-frequency filter in which the length of the inter-port waveguide 26 is 11.3 mm, 12.0 mm, and 12.5 mm, respectively. FIG. 4 shows S11 and S21.

  An effective dielectric constant of a waveguide having a width of 0.5 mm formed on a MgO substrate having a thickness of 0.5 mm is 6.50. Therefore, the wavelength of the high frequency signal of 5 GHz propagating through this waveguide is 23.5 mm. Accordingly, the line lengths of the inter-port waveguides 26 having the lengths of 11.3 mm, 12.0 mm, and 12.5 mm are 0.48 times, 0.51 times, and 0.53 times the in-line wavelength of the high-frequency signal, respectively. Double. The length obtained by normalizing the line length of the waveguide with the in-line wavelength of a signal having a specific frequency propagating through the waveguide is referred to as “electric line length”.

  In any high frequency filter, S21 shows the maximum value in the vicinity of the frequency of 5 GHz, and attenuation poles appear on both sides thereof. The S11 parameter shows two steep minimum values near the frequency of 5 GHz. This indicates that dual mode resonance occurs in the resonance pattern 21. The distance between the two minimum values increases as the electrical line length of the inter-port waveguide 26 increases. In addition, the passband width of S21 increases as the electrical line length of the inter-port waveguide 26 increases. This means that the dual mode coupling becomes stronger as the electrical line length of the inter-port waveguide 26 becomes longer.

  The change in the pass band due to the electrical line length of the inter-port waveguide 26 can be explained by the inter-resonance coupling coefficient k. Assuming that two different resonance frequencies when dual mode resonance occurs are fl and fh (fl <fh), the inter-resonance coupling coefficient k is expressed by the following equation.

k = (fh ² −fl ² ) / (fh ² + fl ² ) (2)
FIG. 5 shows changes in the inter-resonance coupling coefficient k when the length of the inter-port waveguide 26 is changed. The horizontal axis in FIG. 5 represents the length of the inter-port waveguide 26 in the unit “mm”, and the vertical axis represents the inter-resonance coupling coefficient k. The horizontal axis on the upper side of FIG. 5 shows the electrical line length of the inter-port waveguide 26 normalized with an in-line wavelength of 23.5 mm of a high frequency signal having a frequency of 5 GHz.

  The inter-resonance coupling coefficient k becomes 0 when the line length of the inter-port waveguide 26 is about 11.3 mm (the electric line length normalized by the in-line wavelength of the high-frequency signal having a frequency of 5 GHz is about 0.48). Bandwidth is the narrowest. When the inter-port waveguide 26 is lengthened, the inter-resonance coupling coefficient k increases. From the graph shown in FIG. 5, it is possible to adjust the passband width by changing the line length of the inter-port waveguide 26 within a range of 56% or less of the in-line wavelength of the high-frequency signal having a frequency of 5 GHz. I understand that. Note that the lower limit value of the line length range in which the passband width can be adjusted may be a length at which the inter-resonance coupling coefficient k is zero.

  The electrical line length of the inter-port waveguide 26 is the geometric length and width, the distance between the first output port 23 and the resonance pattern 21, the distance between the second input port 24 and the resonance pattern 21, And the dielectric constant of the space around the inter-port waveguide 26. Therefore, by changing these parameters, the electrical line length of the inter-port waveguide 26 can be changed.

  FIG. 6A shows a pattern on the main surface of the dielectric substrate 20 in the case where the electrical line length of the inter-port waveguide 26 is substantially equal to the in-line wavelength corresponding to the fundamental resonance frequency.

  FIG. 6B shows a simulation result of the transmission characteristics (frequency dependence of S21) of the high-frequency filter when the line length of the inter-port waveguide 26 is changed within a range of 20.5 mm to 24.5 mm. The horizontal axis represents the frequency in the unit “GHz”, and the vertical axis represents the size of S21 in the unit “dB”. S21 shows the maximum value in the vicinity of the frequency of 5 GHz, and it can be confirmed that oscillation in the dual mode occurs. However, unlike the case shown in FIG. 4, no attenuation poles are observed on both sides of the frequency indicating the maximum value.

  In the range of the line length of the inter-port waveguide 26 from 20.5 mm to 24.5 mm, the transmission band shifts to the low frequency side as the line length increases. The transmission characteristics show the same tendency when the line length of the inter-port waveguide 26 is in the range of 0.9 to 1.1 times the in-line wavelength corresponding to the fundamental resonance frequency. In this way, the transmission band can be shifted by changing the line length of the inter-port waveguide 26 within a range of 0.9 to 1.1 times the in-line wavelength corresponding to the fundamental resonance frequency. It is.

  FIG. 7A shows a conductive pattern on a dielectric substrate of the high frequency filter according to the second embodiment. The high-frequency filter according to the first embodiment has a one-stage configuration having one resonance pattern 21, but the high-frequency filter according to the second embodiment has a two-stage configuration. The first-stage conductive pattern is the same as the conductive pattern of the high-frequency filter of the first embodiment shown in FIGS. 1A and 1B. The second-stage conductive pattern is equivalent to a rotated mirror image of the first-stage conductive pattern. The resonance pattern 21A, the third input port 22A, the third output port 23A, the fourth input port 24A, the fourth output port 25A, and the inter-port waveguide 26A of the second-stage conductive pattern are respectively This corresponds to the resonance pattern 21, the first input port 22, the first output port 23, the second input port 24, the second output port 25, and the inter-port waveguide 26 of the high-frequency filter according to one embodiment.

  As described above, the second-stage conductive pattern is equal to the mirror image of the first-stage conductive pattern. Therefore, when viewed toward the main surface of the dielectric substrate 20, the direction of rotation from the first output port 23 to the second input port 24 with reference to the center of the first-stage resonance pattern 21 (see FIG. 7A) and the direction of rotation from the third output port 23A to the fourth input port 24A (clockwise in FIG. 7A) with respect to the center of the second-stage resonance pattern 21A as a reference. become.

  The interstage waveguide 50 connects the second output port 25 of the first stage and the third input port 22A of the second stage. The line length of the interstage waveguide 50 is 3/8 times the in-line wavelength corresponding to the fundamental resonance frequency.

  FIG. 7B shows a conductive pattern on the dielectric substrate of the high-frequency filter according to the comparative example. In the second embodiment, the second-stage conductive pattern coincided with the mirror image of the first-stage conductive pattern, but in the comparative example, the first-stage conductive pattern itself was rotated. Match the one. The resonance pattern 21B, the third input port 22B, the third output port 23B, the fourth input port 24B, the fourth output port 25B, and the inter-port waveguide 26B of the second-stage conductive pattern are respectively This corresponds to the resonance pattern 21, the first input port 22, the first output port 23, the second input port 24, the second output port 25, and the inter-port waveguide 26 of the high-frequency filter according to one embodiment.

  Since the second-stage conductive pattern coincides with the rotation of the first-stage conductive pattern itself, when viewed toward the main surface of the dielectric substrate 20, the center of the first-stage resonance pattern 21 is obtained. With reference to the rotation direction (clockwise in FIG. 7B) from the first output port 23 to the second input port 24 and the center of the second-stage resonance pattern 21B as a reference. The direction of rotation from 23B to the fourth input port 24B (clockwise in FIG. 7B) is the same.

  The interstage waveguide 50 connects the second output port 25 of the first stage and the third input port 22B of the second stage. The line length of the interstage waveguide 50 is 3/8 times the in-line wavelength corresponding to the fundamental resonance frequency.

  FIG. 8 shows the simulation results of the transmission characteristics (frequency dependence of S21) of the high-frequency filter according to the second embodiment and the comparative example. The horizontal axis represents the frequency in the unit “GHz”, and the vertical axis represents the size of S21 in the unit “dB”. The solid line in the figure shows S21 of the high-frequency filter according to the second embodiment shown in FIG. 7A, and the broken line shows S21 of the high-frequency filter according to the comparative example shown in FIG. 7B. In either case, band-pass filter characteristics having a transmission band centered at a frequency of about 5 GHz are shown.

  In the case of the second embodiment, two attenuation poles appear on both sides of the transmission band. On the other hand, the attenuation pole does not appear in the comparative example. As in the second embodiment, the frequency cutoff characteristic can be made steeper by making the first-stage conductive pattern and the second-stage conductive pattern have a mirror image relationship. As described above, the transmission characteristics of the high-frequency filter according to the second embodiment and the high-frequency filter according to the comparative example show different behavior because the electromagnetic waves radiated upward from the first-stage and second-stage resonance patterns are different from each other. It is thought that it influences each other.

  FIG. 9 shows a case where the line length of the interstage waveguide 50 of the high-frequency filter according to the second embodiment is made equal to the in-line wavelength corresponding to the fundamental resonance frequency, 3/8 times the in-line wavelength, and the line The transmission characteristics (frequency dependence of S21) when the inner wavelength is ½ times are shown. The horizontal axis represents the frequency in the unit “GHz”, and the vertical axis represents the size of S21 in the unit “dB”. When the electrical line length of the interstage waveguide 50 is equal to the in-line wavelength corresponding to the fundamental resonance frequency, the thin line, the thick line, and the broken line in the figure are each 3/8 times the in-line wavelength, and The simulation result of the S21 parameter when the wavelength in the line is ½ times is shown.

When the electrical line length of the interstage waveguide 50 is made equal to the in-line wavelength, a resonance peak p _L appears on the low frequency side of the transmission band. In the case where the electrical line length of the stage between the waveguides 50 to 1/2 of the line in the wavelength, the high-frequency side of the transmission band, the resonance peak p _H has appeared. On the other hand, when the electrical line length of the interstage waveguide 50 is 3/8 times the in-line wavelength, good bandpass filter characteristics are obtained.

  As can be seen from this evaluation result, it is preferable to set the electrical line length of the interstage waveguide 50 to 3/8 times the in-line wavelength corresponding to the fundamental resonance frequency.

  In the second embodiment, the high-frequency filter is configured with two stages, but a multi-stage configuration with three or more stages may be employed. In this case, in order to make the frequency cutoff characteristic steep, it is preferable that the odd-numbered conductive patterns and the even-numbered conductive patterns have a mirror image relationship with each other.

  In the first and second embodiments described above, the planar shape of the input / output port is a crescent shape, but may be other shapes that can be electromagnetically coupled to the resonance pattern.

  FIG. 10 shows a cross-sectional view of the main part of the high-frequency filter according to the third embodiment. In the first and second embodiments, the high frequency filter is configured by a microstrip line in which the ground film 27 is disposed only on one side of the conductive pattern. In the third embodiment, the high-frequency filter is configured by a strip line in which ground films are arranged on both sides of the conductive pattern.

  The configuration of the dielectric substrate 20, the conductive patterns 21, 22, 23 on the main surface, and the ground film 27 on the back surface thereof are the same as the configuration of the high frequency filter of the first embodiment. A dielectric film 60 is disposed on the main surface of the dielectric substrate 20 so as to cover the conductive patterns 21, 22, 23 and the like. An upper ground film 61 is formed on the surface of the dielectric film 60.

  As described above, the strip line structure can achieve the same effect as the high frequency filter of the microstrip line structure of the first embodiment. Further, the inner layer conductive patterns 21, 22, 23, etc. may have a plurality of stages as in the high frequency filter according to the second embodiment.

  FIG. 11A shows a cross-sectional view of the high-frequency filter according to the fourth embodiment. FIG. 11B is a plan sectional view taken along one-dot chain line 11B-11B in FIG. 11A. A cross-sectional view taken along one-dot chain line 11A-11A in FIG. 11B corresponds to FIG. 11A. Hereinafter, description will be made by paying attention to different points from the high-frequency filter according to the first embodiment shown in FIGS. 1A and 1B, and redundant description of parts having the same configuration will be omitted.

  A first dielectric member 70 and a second dielectric member 71 are disposed above the dielectric substrate 20. The first dielectric member 70 is disposed in the vicinity of the coupling portion between the resonance pattern 21 and the first output port 23, and the second dielectric member 71 is formed between the resonance pattern 21 and the second input port 24. It is arranged in the vicinity of the coupling part. Here, “near” can be defined as a range affected by an electromagnetic field generated at the coupling portion between the resonance pattern 21 and the input / output ports 23 and 24.

  The first dielectric member 70 is supported on the package 15 by the first support member 72. The first support member 72 can raise and lower the first dielectric member 70. That is, the distance between the first dielectric member 70 and the substrate 20 can be changed. In the state where the first dielectric member 70 is lowered most, the first dielectric member 70 contacts the resonance pattern 21 and the first output port 23.

  As the first support member 72, for example, a screw that is screwed into a through-hole formed in the top plate 15B of the package 15 can be used. By rotating the screw, the first dielectric member 70 can be moved up and down. The first support member 72 may be a linear actuator that translates an object by a drive signal from the outside.

  Similar to the first dielectric member 70, the second dielectric member 71 is supported by the second support member 73 so as to be movable up and down.

  When the first dielectric member 70 and the second dielectric member 71 are raised and lowered, the capacitance between the resonance pattern 21 and the first output port 23, and the resonance pattern 21 and the second input port 24. The capacitance during the change. Thereby, the transmission characteristics and reflection characteristics of the high-frequency filter change.

  FIG. 12 shows the frequency dependence of the S parameter of the high frequency filter according to the fourth embodiment. The solid line in FIG. 12 shows the S parameter when the first dielectric member 70 and the second dielectric member 71 are not arranged, and the broken line shows the first dielectric member 70 with the resonance pattern 21 and the first dielectric member 70. The simulation result of the S parameter in a state where the second dielectric member 71 is brought into contact with the output port 23 and the second dielectric member 71 is brought into contact with the resonance pattern 21 and the second input port 24 is shown. As the first dielectric member 70 and the second dielectric member 71, MgO processed into a disk shape having a thickness of 0.5 mm and a diameter of 2 mm was used.

  When the first dielectric member 70 and the second dielectric member 71 are arranged, it can be seen that the transmission bandwidth is widened. At this time, the center frequency hardly changes. When a gap is provided between the first dielectric member 70 and the substrate 20 and between the second dielectric member 71 and the substrate 20, the transmission bandwidth is arranged as shown in FIG. The size is intermediate between the case where it is placed and the case where it is not placed. By changing the gap, the transmission bandwidth can be changed.

  In order to improve the controllability of the transmission bandwidth, it is preferable to arrange the first dielectric member 70 and the second dielectric member 71 in a region where the electromagnetic field is strong. For example, it is preferable to arrange the first dielectric member 70 so as to overlap with the gap between the resonance pattern 21 and the first output port 23 in plan view. The second dielectric member 71 is preferably arranged so as to overlap the gap between the resonance pattern 21 and the second input port 24 in plan view.

  Further, the first dielectric member 70 and the second dielectric member 70 are set so that the distance between the first dielectric member 70 and the substrate 20 and the distance between the second dielectric member 71 and the substrate 20 are 10 mm or less. It is preferable that the body member 71 be arranged.

  In the fourth embodiment, the first dielectric member 70 and the second dielectric member 71 are disk-shaped, but other geometric shapes such as a cylindrical shape, a cube, a rectangular parallelepiped, and the like may be used.

In the fourth embodiment, MgO is used for the first dielectric member 70 and the second dielectric member 71, but other dielectric materials may be used. In order to improve controllability of the transmission bandwidth and reduce loss, it is preferable to select a material having a high dielectric constant and a small dielectric loss. Examples of such a material include SrTiO ₃ , TiO ₂ , and Al ₂ O ₃ other than MgO. Further, the first dielectric member 70 and the first support member 72 may be integrally formed from one dielectric material. Similarly, the second dielectric member 71 and the second support member 73 may be integrally formed from one dielectric material.

  When the dielectric member is disposed in the vicinity of the coupling portion between the resonance pattern 21 and the first input port 22 and the coupling portion between the resonance pattern 21 and the second output port 25, the transmission bandwidth hardly changes. The steepness of transmission characteristics changes. Therefore, in order to control the transmission bandwidth, the dielectric member is placed near the coupling portion between the resonance pattern 21 and the first output port 23 and at the coupling portion between the resonance pattern 21 and the second input port 24. It is preferable to arrange in at least one of the vicinity.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  Based on the first to fourth embodiments, the invention disclosed in the following supplementary notes is disclosed.

(Appendix 1)
A substrate made of a dielectric material;
A first resonance pattern having a circular planar shape formed of a conductive material on the main surface of the substrate;
A first electromagnetically coupled to the first resonance pattern at one intersection of the first imaginary straight line passing through the center of the first resonance pattern and the outer periphery of the first resonance pattern An input port;
A first output port that electromagnetically couples to the first resonance pattern at the other intersection of the first imaginary straight line and the outer periphery of the first resonance pattern;
The first resonance at one intersection of a second imaginary line that passes through the center of the first resonance pattern and is orthogonal to the first imaginary line, and an outer peripheral line of the first resonance pattern. A second input port electromagnetically coupled to the pattern;
A second output port that electromagnetically couples to the first resonance pattern at the other intersection of the second imaginary straight line and the outer periphery of the first resonance pattern;
A high-frequency filter having a first inter-port waveguide that propagates a high-frequency signal output to the first output port to the second input port.

(Appendix 2)
The high frequency filter according to appendix 1, wherein a line length of the first inter-port waveguide is 56% or less of an in-line wavelength corresponding to a fundamental resonance frequency of the first resonance pattern.

(Appendix 3)
The high frequency filter according to appendix 1, wherein a line length of the first inter-port waveguide is in a range of 90% to 110% of an in-line wavelength corresponding to a fundamental resonance frequency of the first resonance pattern.

(Appendix 4)
The first input port, the first output port, the second input port, the second output port, and the inter-port waveguide are configured by a conductive pattern made of a conductive material formed on the main surface of the substrate. 4. The high frequency filter according to any one of supplementary notes 1 to 3.

(Appendix 5)
The first resonance pattern, the first input port, the first output port, the second input port, the second output port, and the first inter-port waveguide exhibit superconductivity at a liquid nitrogen temperature. The high frequency filter according to appendix 4, which is formed of a conductive material.

(Appendix 6)
The high frequency filter according to any one of appendices 1 to 5, further comprising a ground film formed on a back surface opposite to the main surface of the substrate.

(Appendix 7)
further,
A second resonance pattern formed of a conductive material on the main surface of the substrate and having a planar shape identical to the first resonance pattern;
A third imaginary line coupled electromagnetically to the second resonance pattern at one intersection of a third imaginary straight line passing through the center of the second resonance pattern and an outer peripheral line of the second resonance pattern; An input port;
A third output port that electromagnetically couples to the second resonance pattern at the other intersection of the third imaginary straight line and the outer periphery of the second resonance pattern;
The second resonance at one intersection of the fourth imaginary line passing through the center of the second resonance pattern and orthogonal to the third imaginary line and the outer peripheral line of the second resonance pattern. A fourth input port electromagnetically coupled to the pattern;
A fourth output port that electromagnetically couples to the second resonance pattern at the other intersection of the fourth imaginary straight line and the outer periphery of the second resonance pattern;
A second inter-port waveguide that propagates the high-frequency signal output to the third output port to the fourth input port;
The high frequency filter according to any one of supplementary notes 1 to 6, further comprising: an interstage waveguide that propagates a high frequency signal output to the second output port to the third input port.

(Appendix 8)
The high frequency filter according to appendix 7, wherein the line length of the interstage waveguide is 3/8 times the in-line wavelength corresponding to the fundamental resonance frequency of the first resonance pattern.

(Appendix 9)
When viewed from the main surface of the substrate, the rotation direction from the first output port to the second input port with respect to the center of the first resonance pattern, and the second resonance pattern The high frequency filter according to appendix 7 or 8, wherein a rotation direction from the third output port to the fourth input port is reverse with respect to the center.

(Appendix 10)
further,
A package that houses and electrically shields the substrate;
A coaxial input connector attached to the package and connected to the input port at the frontmost stage among the input / output ports on the substrate;
10. The high frequency filter according to any one of appendices 1 to 9, further comprising: a coaxial output connector attached to the package and connected to an output port at a rearmost stage among input / output ports on the substrate.

(Appendix 11)
further,
Within the range affected by the electromagnetic field generated at at least one of the coupling location between the first resonance pattern and the first output port and the coupling location between the first resonance pattern and the second input port. A dielectric member disposed in
The high frequency filter according to any one of appendices 1 to 10, further comprising a support member that supports the dielectric member so that a distance between the substrate and the dielectric member can be changed.

(Appendix 12)
The high frequency filter according to appendix 11, wherein the support member includes an actuator for moving the dielectric member up and down relative to the substrate.

(1A) is a sectional view of the high-frequency filter according to the first embodiment, and (1B) is a plan sectional view thereof. (2A) is a graph showing the simulation results of the transmission characteristics of the high-frequency filter according to the first embodiment and the comparative example, and (2B) is a plan view showing the conductive pattern of the high-frequency filter according to the comparative example. It is a graph which shows the actual measurement result of the transmission characteristic and reflection characteristic of the high frequency filter by a 1st Example. It is a graph which shows the simulation result of the permeation | transmission and reflection characteristic of the some sample which varied the electrical line length of the waveguide between the ports of the high frequency filter by a 1st Example. It is a graph which shows the relationship between the length of the waveguide between ports, and the coupling coefficient between resonance. (6A) is a plan view showing a conductive pattern when the electrical line length of the inter-port waveguide of the high-frequency filter of the first embodiment is substantially the fundamental resonance wavelength, and (6B) is an inter-port waveguide. It is a graph which shows the simulation result of the permeation | transmission characteristic of the some sample which varied the electrical line length of. (7A) is a plan view showing the conductive pattern of the high-frequency filter according to the second embodiment, and (7B) is a plan view showing the conductive pattern of the high-frequency filter according to the comparative example. It is a graph which shows the simulation result of the permeation | transmission characteristic of the high frequency filter by a 2nd Example and a comparative example. It is a graph which shows the simulation result of the permeation | transmission characteristic of the some sample which varied the electrical line length of the waveguide between the stages of the high frequency filter by a 2nd Example. It is sectional drawing of the principal part of the high frequency filter by a 3rd Example. (11A) is a sectional view of the high-frequency filter according to the fourth embodiment, and (11B) is a plan sectional view thereof. It is a graph which shows the simulation result of the frequency dependence of the S parameter of the high frequency filter by a 4th example. (13A) is a plan view of a conductive pattern of a conventional high-frequency filter, and (13B) is a cross-sectional view of a main part of the conventional high-frequency filter.

Explanation of symbols

15 Package 20 Dielectric Substrate 21 Resonant Pattern 22 First Input Port 23 First Output Port 24 Second Input Port 25 Second Output Port 26 Interport Waveguide 27 Ground Film 31 Input Waveguide 32 Output Waveguide 35 Input connector 36 Output connector 40 First virtual straight line 41 Second virtual straight line 50 Interstage waveguide 60 Dielectric film 61 Upper ground film 70 First dielectric member 71 Second dielectric member 72 First support member 73 Second support member

Claims (10)

A substrate made of a dielectric material;
A first resonance pattern having a circular planar shape formed of a conductive material on the main surface of the substrate;
A first electromagnetically coupled to the first resonance pattern at one intersection of the first imaginary straight line passing through the center of the first resonance pattern and the outer periphery of the first resonance pattern An input port;
A first output port that electromagnetically couples to the first resonance pattern at the other intersection of the first imaginary straight line and the outer periphery of the first resonance pattern;
The first resonance at one intersection of a second imaginary line that passes through the center of the first resonance pattern and is orthogonal to the first imaginary line, and an outer peripheral line of the first resonance pattern. A second input port electromagnetically coupled to the pattern;
A second output port that electromagnetically couples to the first resonance pattern at the other intersection of the second imaginary straight line and the outer periphery of the first resonance pattern;
A first inter-port waveguide for propagating a high-frequency signal output to the first output port to the second input port ;
A high-frequency filter having a ground film formed on a surface of the substrate opposite to the main surface .   2. The high-frequency filter according to claim 1, wherein a line length of the first inter-port waveguide is 56% or less of an in-line wavelength corresponding to a fundamental resonance frequency of the first resonance pattern.   2. The high-frequency filter according to claim 1, wherein a line length of the first inter-port waveguide is in a range of 90% to 110% of an in-line wavelength corresponding to a fundamental resonance frequency of the first resonance pattern.   The first input port, the first output port, the second input port, the second output port, and the inter-port waveguide are configured by a conductive pattern made of a conductive material formed on the main surface of the substrate. The high frequency filter according to claim 1, wherein the high frequency filter is provided. further,
A second resonance pattern formed of a conductive material on the main surface of the substrate and having a planar shape identical to the first resonance pattern;
A third imaginary line coupled electromagnetically to the second resonance pattern at one intersection of a third imaginary straight line passing through the center of the second resonance pattern and an outer peripheral line of the second resonance pattern; An input port;
A third output port that electromagnetically couples to the second resonance pattern at the other intersection of the third imaginary straight line and the outer periphery of the second resonance pattern;
The second resonance at one intersection of the fourth imaginary line passing through the center of the second resonance pattern and orthogonal to the third imaginary line and the outer peripheral line of the second resonance pattern. A fourth input port electromagnetically coupled to the pattern;
A fourth output port that electromagnetically couples to the second resonance pattern at the other intersection of the fourth imaginary straight line and the outer periphery of the second resonance pattern;
A second inter-port waveguide that propagates the high-frequency signal output to the third output port to the fourth input port;
5. The high-frequency filter according to claim 1, further comprising: an interstage waveguide that propagates a high-frequency signal output to the second output port to the third input port. 6.   The high-frequency filter according to claim 5, wherein a line length of the interstage waveguide is 3/8 times an in-line wavelength corresponding to a fundamental resonance frequency of the first resonance pattern.   When viewed from the main surface of the substrate, the rotation direction from the first output port to the second input port with respect to the center of the first resonance pattern, and the second resonance pattern 7. The high frequency filter according to claim 5, wherein a rotation direction from the third output port to the fourth input port is reverse with respect to the center. further,
A package that houses and electrically shields the substrate;
A coaxial input connector attached to the package and connected to the input port at the frontmost stage among the input / output ports on the substrate;
The high-frequency filter according to claim 1, further comprising: a coaxial output connector attached to the package and connected to the output port at the rearmost stage among the input / output ports on the substrate. further,
Within the range affected by the electromagnetic field generated at at least one of the coupling location between the first resonance pattern and the first output port and the coupling location between the first resonance pattern and the second input port. A dielectric member disposed in
9. The high-frequency filter according to claim 1, further comprising a support member that supports the dielectric member so that a distance between the substrate and the dielectric member can be changed.   The high frequency filter according to claim 9, wherein the support member includes an actuator for moving the dielectric member up and down relative to the substrate.

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