JP2007166270A - Short-circuiting means, and tip short-circuiting stub therewith, resonator and high-frequency filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a short-circuiting means which can enhance the yield of a microwave and millimeter-wave circuit having a short-circuiting means, by reducing the characteristic variations of the short-circuiting means constituted by connecting a signal conductor and a ground conductor through a short-circuiting conductor, in various microwave and millimeter-wave circuits, constituted by using a transmission line consisting of the signal conductor and the ground conductor, and to provide a sharp point short-circuiting stub equipped with the short-circuiting means, a resonator, and a high-frequency filter. <P>SOLUTION: The short-circuiting means comprises the coupling line 10 of a four terminal circuit, where two transmission lines 11a and 11b are arranged substantially in parallel and are subjected to electromagnetic field coupling mutually, a connection line 12 for connecting the two transmission lines, and a short-circuiting conductor 4. Two adjoining terminals are connected electrically by the connection line 12 on one side of the coupling line 10. On the other side, one of two adjoining terminals is short-circuited to the ground conductor by the short-circuiting conductor 4, and the remaining terminal serves as an I/O terminal for connection with an external circuit, thus constituting the short-circuiting means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a short-circuit means for a high-frequency circuit used in a microwave band and a millimeter-wave band, and mainly includes a tip short-circuit stub, a resonator, or a tip short-circuit stub composed of a microstrip line, a strip line, etc. The present invention relates to a short-circuit means serving as a component of a circuit such as a filter configured using a resonator and an impedance matching circuit.

  As a short-circuit means for conventional high-frequency circuits, the strip conductor and ground conductor are electrically connected to a dielectric substrate with the strip conductor and tip short-circuit stub as the signal conductor formed on the main surface and the ground conductor formed on the back surface. Some have a through-hole that functions as a short-circuit conductor to be electrically short-circuited by the through-hole.

  By the way, the tip short-circuit stub has a simple structure and is used very often. However, since the manufacturing process for forming the strip conductor on the main surface of the dielectric substrate and the manufacturing process for forming the through hole are usually different, The variation of the position of the through hole with respect to the strip conductor is inevitable. When the through hole is misaligned, the electrical length of the tip short-circuit stub changes by the electrical length corresponding to the misalignment. Therefore, the reference plane for considering the electrical characteristics of the stub (the strip conductor and the tip short-circuit stub There is a problem that the reflection characteristic (input impedance) when the stub side is viewed from the connection portion varies. In particular, when the through hole is displaced with respect to the strip conductor in the longitudinal direction of the tip short-circuited stub, the reflection characteristic varies significantly. These problems often occur not only in the short-circuited short stubs, but also in microstrip line resonators constructed using similar shorting means, filters, amplifiers, impedance matching circuits of antennas, etc. Reduce.

Yoshihiro Konishi, “Basics and Applications of Microwave Circuits”, General Electronic Publishing, page 308

  As described above, the conventional short-circuit means avoids fluctuations in circuit characteristics due to the short-circuit conductor that electrically connects the strip conductor as the signal conductor and the ground conductor being displaced from a predetermined position with respect to the signal conductor. However, there is a problem that the yield of the circuit is lowered due to characteristic variation. This problem becomes more prominent as the frequency increases and the amount of positional deviation with respect to the wavelength increases.

  The present invention has been made to solve the above-described problems. In various microwave millimeter wave circuits configured using a transmission line composed of a signal conductor and a ground conductor, the signal conductor and the ground conductor are short-circuited. Short-circuit means capable of reducing fluctuations in characteristics of the short-circuit means constituted by connecting with a conductor and improving the yield of the microwave millimeter-wave circuit having the short-circuit means as described above, and a tip short-circuit stub including the short-circuit means, The object is to obtain a resonator and a high-frequency filter.

  The short-circuit means according to the present invention includes a four-terminal circuit coupling line in which two transmission lines are arranged substantially in parallel and coupled to each other, a connection line connecting the two transmission lines, and a short-circuit conductor. Two terminals adjacent on one side of the coupling line are electrically connected by the connection line, and one of the two terminals adjacent on the other side is grounded by the short-circuit conductor The other terminals are used as input / output terminals for connection to an external circuit.

  A short-circuit means according to another invention includes two short-circuit means having the same configuration as the short-circuit means described above, and two relay lines composed of transmission lines having substantially the same electrical length. Both coupled lines are arranged so as to be substantially parallel, and one end of the relay line is connected to the input / output terminals of the two short-circuit means, and the other end of the relay line is electrically connected, The connection location is used as an input / output terminal for connecting to the external circuit.

  Further, the short-circuit means according to another invention includes a 6-terminal circuit coupling line in which three transmission lines are arranged substantially in parallel and coupled to each other, a connection line connecting the three transmission lines, and a short-circuit. A conductor and two relay lines composed of transmission lines having substantially the same electrical length, electrically connecting three adjacent terminals on one side of the coupling line with the connection line and adjacent on the other side Of the three terminals, one of the center is short-circuited to the ground conductor by the short-circuit conductor, and one end of the relay line is connected to each of the remaining two terminals on both sides. The ends are electrically connected, and the connection location is used as an input / output terminal for connecting to the external circuit.

  Further, the short-circuit means according to still another invention includes a coupling line of a six-terminal circuit in which three transmission lines are arranged substantially in parallel and are electromagnetically coupled to each other, a connection line connecting the three transmission lines, Two short-circuit conductors, and electrically connecting three adjacent terminals on one side of the coupling line with the connection line, and two terminals on both sides among the three terminals adjacent on the other side Each of these is short-circuited to the ground conductor with a short-circuit conductor, and the center terminal is used as the input / output terminal.

  Furthermore, the tip short-circuit stub, the resonator, or the high-frequency filter according to the present invention includes any one of the short-circuit means described above.

  According to the present invention, two terminals on one side of a coupling line formed by electromagnetically coupling two short lines arranged substantially in parallel are combined into one, and one of the two terminals on the other side is combined. The ground conductor and the strip conductor are short-circuited by a through hole or the like, and the remaining terminal is used as a short-circuit means as an input terminal for connecting to another circuit. For this reason, even if the through hole is displaced with respect to the strip conductor, the characteristic variation of the circuit configured using the short-circuiting means is small, and a circuit with a good yield can be obtained.

  In addition, the two short-circuiting means described above were used, connected in parallel, and laid out so as to be symmetric with respect to the center line of the short-circuiting means. For this reason, even if the through hole is displaced in any direction with respect to the strip conductor, the characteristic variation as the short-circuiting means can be suppressed, and a circuit with a good yield can be obtained.

  In addition, in a coupled line formed by electromagnetically coupling three short lines arranged substantially parallel to each other, the three terminals on one side are combined into one, and the central terminal on the other side is grounded through a ground conductor. The transmission lines are connected to the remaining two terminals, and one end of these transmission lines is connected in parallel to form a short-circuit means. For this reason, the characteristic variation due to the displacement of the through hole with respect to the strip conductor is small, and the use of the short-circuit means has an effect of obtaining a compact and high-yield circuit.

  Further, three terminals on one side of a coupling line formed by electromagnetically coupling three parallel lines that are substantially parallel to each other are combined into one, and the terminals on both sides on the other side are short-circuited to the ground conductor with a through hole, and The remaining central terminal serves as a short-circuit means with the input terminal as an input terminal. For this reason, even if the position shift of the through hole occurs with respect to the conductor pattern, the characteristic variation of the circuit configured using the short-circuit means is small. In addition, there is an effect that a compact short-circuiting means can be obtained because the number of wiring lines is small.

  Furthermore, a resonator or a filter was configured using any of the short-circuit means described above. For this reason, there is an effect that a resonator or a filter with less fluctuation of the resonance frequency can be obtained. In addition, there is an effect that it is possible to realize a filter having an electrical characteristic that is difficult to realize by using a conventional short-circuiting means, such as when a band to suppress the passage of microwaves is close to a band to be passed. .

Embodiment 1 FIG.
FIG. 1 is a view of a microstrip line type short-circuited short-circuited stub configured using the short-circuit means of the high-frequency circuit according to Embodiment 1 of the present invention, and FIG. 2 is a view shown in FIG. It is arrow sectional drawing in the line AA '. As shown in FIGS. 1 and 2, a strip conductor 2 as a signal conductor and a tip short-circuit stub 5 are formed on the main surface of the dielectric substrate 1, and a ground conductor 3 is formed on the back surface. Further, a through hole 4 that functions as a short-circuit conductor that electrically connects the strip conductor 2 and the ground conductor 3 is formed in the main surface of the dielectric substrate 1. 6 is a main line to which the tip short-circuit stub 5 is connected, 7a and 7b are input / output terminals, 8 is a short-circuit means for electrically short-circuiting the strip conductor 2 and the ground conductor 3 through the through-hole 4, and 9 is a tip short-circuit stub. 5 shows a reference plane for considering the electrical characteristics of No. 5.

  3A to 3C show a top view, a partially exploded view, and an equivalent circuit diagram of the tip short-circuit stub 5 according to Embodiment 1 similar to FIG. In FIG. 3A, reference numeral 10 denotes a coupling line formed by electromagnetically coupling two microstrip lines arranged substantially in parallel. 11a and 11b denote two transmission lines serving as signal conductors of the coupling line 10. Indicates a short connection line connecting the transmission lines 11a and 11b.

That is, as shown in FIG. 3B, the tip short-circuit stub 5 according to the first embodiment has two transmission lines 11a and 11b having an electrical length of 1/8 wavelength or less in the use frequency band substantially parallel to each other. And a coupling line 10 of a four-terminal circuit that is electromagnetically coupled to each other, a connection line 12, and a through-hole 4 (including a conductor pattern 13 associated with the through-hole 4) as a short-circuit conductor. Two terminals on one side of the line 10 are connected by a connection line 12, one of the two terminals on the other side is connected to the ground conductor 3 and the strip conductor 2 by a through hole 4, and the remaining other terminal This is a tip short-circuited stub having a coupled-line-type short-circuit means, which is used as an input / output terminal for connecting one terminal to the main line 6. Electrical length coupling degree (the coupled line impedance) coupling line 10, at the design center frequency f _0, is selected values so as to satisfy a predetermined condition.

Next, the operation will be described.
First, as shown in FIG. 3 (a), the tip short-circuit stub 5 is divided into two parts, A part and C part, and as shown in FIG. 3 (c), the input impedance of C part is _Xc , and the coupled line part. electrical length theta _c of the coupled line impedance _{Z e} (even mode _impedance), and _{Z oo} (odd mode impedance). In this case, the input impedance _{X c,} the rate of change for the electric length theta _c of _{X c} is expressed by the following equation (1).

Next, as shown in FIG. 4, the portion C in FIG. 3 is replaced with a certain electric length θ _s and characteristic impedance Z _s (Z _s is equal to or close to Z _a at an arbitrary design center frequency f ₀ . Consider replacing the circuit with a ground conductor at the tip of the transmission line. The input impedance of the circuit and X _s. At this time, the rate of change for the electric length theta _c of the input impedance _{X s} and, _{X s} is given by the following equation (2).

Here, it is assumed that the following conditional expression (3) is satisfied at the design center frequency f ₀ .

  Next, when the expression (3) is satisfied, what happens to the characteristics of the tip short-circuit stub 5 of the first embodiment when the displacement of the through hole 4 with respect to the strip conductor 2 occurs in the x direction in FIG. Explain how. First, FIG. 5 is a view of the circuit of FIG. 1 as viewed from above when the through hole 4 is displaced by a minute electrical length Δ in the −x direction with respect to the pattern of the strip conductor 2, and at that time An equivalent circuit is shown. In the top view of the circuit, the position where the through hole 4 should be originally is indicated by a dotted line.

In this case, the electric length theta _c Part C short-circuit stub 5 is extended by delta, while the electrical length theta _a part A is shortened by delta. Assuming that Expression (3) holds, the part C is substantially equal to the short-circuited end circuit having the electrical length θ _s + Δ and the characteristic impedance Z _s as shown in FIG. Therefore, the short-circuited stub 5 is a cascade connection of _a transmission line having an electrical length θ _a −Δ and a characteristic impedance Z _a and _a short-circuited line having an electrical length θ _s + Δ and a characteristic impedance Z _s (≈Z _a ). , the input impedance from the reference surface 9 allow for short-circuit stub 5 X _a is hardly changed from the case of FIG. 4 when no positional deviation.

On the other hand, FIG. 6 shows a case where the through hole 4 is displaced from the pattern of the strip conductor 2 by a minute electric length Δ in the + x direction. Similarly to the case where the positional deviation occurs in the −x direction, if the equation (3) is satisfied, X _c and X _s substantially coincide with each other even after the positional deviation occurs, and the C portion as shown in FIG. Substitution is established. As a result, the input impedance X _a stub invariable from no positional deviation state.

Incidentally, the equation (3), for _{simplification,} and _{Z e = Z s = Z a} , when the simultaneous equations to unknowns theta _c and _{Z oo,} numerically the theta _c and _{Z oo} for any theta _s Can be requested. FIG. 7 shows an example of the calculation result. The solution is obtained for three cases of Z _e = 40, 50, 60Ω. As an example, FIG. 8 shows the calculation result of the characteristic variation calculation result of the characteristic variation of the short-circuit means described in the first embodiment. The characteristic fluctuation of the input impedance X as a short-circuit means when the design center frequency is 10 GHz and the positional deviation of the through hole 4 is 2.5 degrees is shown. Incidentally, an electrical length of 2.5 degrees at 10 GHz corresponds to a physical length of about 80 μm when a circuit is configured with a microstrip line using a dielectric substrate with er = 10. In addition, m1-m3 shows the value of the reflection phase in 10 GHz.

In FIG. 8, the frequency characteristic of the reflection phase of the circuit is graphed instead of the input impedance, and the reflection phases of three cases of no positional deviation, positional deviation in the + x direction, and positional deviation in the −x direction are overwritten. . The impedance of the coupled line is Z _e = 50Ω, Z _oo = 24.5Ω, and the electrical length θ _c is 10 degrees. These values correspond to values when θ _s is 10 degrees in FIG. 7 (actually a value slightly smaller than 10 degrees). As can be seen from the graph, at the design center frequency f ₀ , it can be seen that the variation of the reflection phase is less than ± 0.1 degrees.

On the other hand, FIG. 9 shows the fluctuation of the reflection phase when a similar through-hole position shift occurs in the conventional short-circuit means. Although the graphs of FIGS. 8 and 9 are shown on the same scale, the conventional short-circuit means causes a reflection phase fluctuation of ± 5 degrees at f ₀ . Thus, it can be seen that the characteristic variation is extremely small in the short-circuit means of the first embodiment.

  In addition, when the through hole position shift occurs in the y direction, the through hole position shift occurs in the width direction of the microstrip line. Therefore, the characteristic variation of the short-circuit means and thus the tip short-circuit stub to which the short-circuit means is applied. Is smaller than the characteristic fluctuation caused by the positional deviation in the x direction.

  By the way, in the above description, for simplification, the influence of the connection line 12 is omitted from the equivalent circuit because the influence of the connection line 12 is small. Even if the connecting line 12 is interposed, there is no change in that a short-circuit means having the same effect can be obtained by finely adjusting parameters such as the electrical length of the coupled line.

  As described above, the characteristic fluctuation of the tip short-circuited stub caused by the positional deviation of the through hole with respect to the strip conductor pattern can be reduced, and a microwave millimeter wave circuit having stable characteristics can be obtained. As a result, there is an effect that a microwave millimeter wave circuit with a high yield can be obtained.

  In the first embodiment, the microstrip line structure has been described. However, the circuit of the first embodiment is another transmission line including a signal line and a ground conductor such as a strip line (triplate line). Needless to say, the same effect can be obtained even in the case of the above.

  Therefore, according to the first embodiment, two terminals on one side of a coupling line formed by electromagnetically coupling two short lines arranged substantially in parallel are combined into one, and two terminals on the other side are combined. One of the two is short-circuited between the ground conductor and strip conductor with a through-hole, etc., and the short-circuit means is used as an input terminal for connecting the remaining terminal to another circuit. Even if this occurs, there is an effect that the characteristic variation of the circuit configured using the short-circuit means is small, and a circuit with a good yield can be obtained.

Embodiment 2. FIG.
FIG. 10 is a top view of the tip short-circuit stub configured using the short-circuit means according to Embodiment 2 of the present invention. The basic structure of the tip short-circuit stub shown in FIG. 10 is the same as that of the tip short-circuit stub described in the first embodiment, but in the case of the second embodiment, the two short-circuit means of the first embodiment are used. These are combined together via the relay lines 14a and 14b, which are transmission lines having substantially the same electrical length, to constitute one short-circuit means. FIG. 11 shows an equivalent circuit of the tip short-circuit stub shown in FIG.

  That is, the tip short-circuit stub according to the second embodiment includes two short-circuit means 8a and 8b that are short-circuit means having the same configuration as that of the first embodiment, and two relay lines 14a and 14b that are constituted by transmission lines having substantially the same electrical length. The two short-circuit means 8a and 8b are arranged so that both coupled lines are substantially parallel, and one end of each of the relay lines 14a and 14b is connected to the input / output terminals of the two short-circuit means 8a and 8b, respectively. At the same time, the other ends of the relay lines 14a and 14b are electrically connected, and short-circuiting means is provided as an input / output terminal for connecting the connection portion to an external circuit.

  The operation and effect of the short-circuit means according to the second embodiment are the same as those of the short-circuit means described in the first embodiment. However, in the case of the second embodiment, two short-circuit means described in the first embodiment are used. The short-circuit means 8a and 8b are configured on the dielectric substrate 1 so as to have a line-symmetric shape with respect to the center line of the tip short-circuit stub. For this reason, as shown in FIG. 12, when the through hole 4 is displaced in the y direction with respect to the conductor pattern, the input impedances Xc1 and Xc2 change in opposite directions to cancel the changes in both impedances. have. Therefore, the characteristic variation as the tip short circuit stub becomes extremely small not only in the x direction but also in the displacement of the through hole in the y direction. Thus, the short-circuit means according to the second embodiment can provide a short-circuit means with less characteristic fluctuation than the short-circuit means described in the first embodiment, and can improve the circuit yield.

  Therefore, according to the second embodiment, the two short-circuit means described in the first embodiment are used, they are connected in parallel, and are laid out so as to be symmetrical with respect to the center line of the short-circuit means. Regardless of the position of the conductor in any direction, the characteristic variation as the short-circuit means can be kept small, and a circuit with a good yield can be obtained.

Embodiment 3 FIG.
FIG. 12 is a top view of the tip short-circuit stub configured using the short-circuit means according to Embodiment 3 of the present invention. The short-circuit means shown in FIG. 12 has a shape similar to that of the second embodiment, but the coupling line is constituted by a coupling line 10 in which three substantially parallel transmission lines 11a, 11b, and 11c are electromagnetically coupled, The three terminals on one side are connected by a connection line, and the center terminal on the other side is short-circuited to the ground conductor by a through hole 4. Furthermore, the transmission lines 14a and 14b having the electrical length θb and the characteristic impedance Zb are connected to the remaining two terminals, respectively, and these transmission lines are connected together. FIG. 13 shows an equivalent circuit of the tip short-circuit stub shown in FIG.

  That is, the tip short-circuit stub according to the third embodiment has a 1/8 wavelength or less in the use frequency band, as in the exploded view shown in FIG. 3B of the tip short-circuit stub according to the first embodiment. A connection line 10 that connects three transmission lines 11a, 11b, and 11c, and a transmission line 11a, 11b, and 11c that have three electrical transmission lines 11a, 11b, and 11c and that are electromagnetically coupled to each other. 12, the short-circuit conductor 4, and two relay lines 14 a and 14 b made of transmission lines having substantially the same electrical length, and three terminals adjacent on one side of the coupled line 10 are electrically connected by the connection line 12. In addition, one of the three terminals adjacent on the other side is short-circuited to the ground conductor 3 by the short-circuit conductor 4, and one end of the relay lines 14a and 14b is connected to each of the remaining two terminals on both sides. And connect 2 Relay line 14a, and electrically connecting the other end of 14b, those having a short-circuit means in the input and output terminals for connecting the connecting portion to an external circuit.

  The short-circuit means of the third embodiment uses a three-wire coupled line as the coupled line, but basically does not differ from the two-wire coupled line with respect to the displacement of the through-hole in the x direction, and the appropriate coupling impedance. By selecting the electrical length, it is possible to reduce the characteristic fluctuation. With respect to the displacement of the through-hole position in the y direction, an imbalance occurs in the currents flowing through the coupling conductors 11a and 11c, but the total is almost constant, and it can be expected that the characteristic variation becomes small. Although this point is the same as the short-circuit means of the second embodiment, the short-circuit means of the present embodiment has an advantage that a single through hole is sufficient and a circuit can be configured in a compact manner.

  Therefore, according to the third embodiment, in a coupled line formed by electromagnetically coupling three short lines arranged substantially parallel to each other, the three terminals on one side are combined into one, and the center on the other side is combined. The terminal is short-circuited to the ground conductor through the through-hole, and the transmission line is connected to each of the remaining two terminals, and one end of these transmission lines is connected in parallel to form a short-circuit means. The variation in characteristics due to the displacement of the through-hole with respect to is small, and the use of the short-circuit means has an effect of obtaining a compact and high-yield circuit.

Embodiment 4 FIG.
FIG. 14 is a top view of the tip short-circuit stub configured using the short-circuit means according to Embodiment 4 of the present invention. The short-circuit means shown in FIG. 14 is composed of a coupling line 10 in which three substantially parallel transmission lines 11a, 11b, and 11c are electromagnetically coupled, as in the third embodiment shown in FIG. The three terminals are connected by the connection line 12, the central terminal on the other side is connected to the main line 2, and the remaining two terminals are short-circuited to the ground conductors by the through holes 4. FIG. 15 shows an equivalent circuit of the tip short-circuit stub shown in FIG.

  That is, the tip short-circuited stub according to the fourth embodiment has three transmission lines 11a, 11b, and 11c having an electrical length of 1/8 wavelength or less in the use frequency band arranged in parallel to each other and electromagnetically coupled to each other. A connection line 12 connecting the three transmission lines 11a, 11b, and 11c, and two short-circuit conductors 4, and three adjacent terminals on one side of the connection line 10 Are electrically connected by the connection line 12, and among the three terminals adjacent on the other side, each of the two terminals on both sides is short-circuited to the ground conductor 3 by the short-circuit conductor 4, and the central terminal is the input / output terminal Short circuit means.

  The short-circuit means according to the fourth embodiment uses a three-wire coupled line as the coupled line 10, but is basically the same as the two-wire coupled line with respect to the displacement of the through hole in the x direction, and is appropriately Variation in characteristics can be reduced by selecting the coupling impedance and the electrical length. With respect to the displacement of the through-hole position in the y direction, an imbalance occurs in the current flowing through the transmission lines 11a and 11c, but the total is almost constant, and the fluctuation of the input impedance Xc can be expected to be small. In the short-circuit means according to the fourth embodiment, two through holes are required. However, depending on the characteristic impedance of the transmission line constituting the short-circuit means and the electrical length, the circuit can be made more compact than the short-circuit means of the third embodiment. There is an advantage that can be configured.

  Therefore, according to the fourth embodiment, three terminals on one side of a coupling line formed by electromagnetically coupling three short lines that are substantially parallel to each other are combined into one, and terminals on both sides on the other side are connected to through holes. Since the short-circuit means is short-circuited with the ground conductor and the remaining central terminal is used as the input terminal, the characteristics of the circuit constructed using the short-circuit means even if a through-hole misalignment occurs with respect to the conductor pattern There is little fluctuation. In addition, there is an effect that a compact short-circuiting means can be obtained because the number of wiring lines is small.

Embodiment 5 FIG.
FIG. 16 is a top view of a filter including a resonator using the short-circuit means according to Embodiment 5 of the present invention. The filter shown in FIG. 16 applies the short-circuit means 8a, 8b, and 8c similar to those of the fourth embodiment as the short-circuit means for the λ / 4 resonators 15a, 15b, and 15c, and the resonators 15a, 15b, and 15c are mainly used. The electromagnetic field coupling is performed in parallel with the line 2. FIG. 17 shows an equivalent circuit thereof.

  The equivalent circuit of the filter of the fifth embodiment is a circuit in which the resonators 15a, 15b, and 15c are loaded in a shunt with respect to the main line 2 at λ / 4 intervals of the resonance frequency. The resonators 15a, 15b, and 15c can be regarded as shunt series resonance circuits. Therefore, the filter of the fifth embodiment completely reflects the microwave incident from the input / output terminal at the resonance frequency. At frequencies far from the resonance frequency, the resonator can be regarded as a capacitive element with a small capacity or an inductive element with a large inductance, so that most of the microwaves that enter the circuit from one input / output terminal pass through the main line. Propagates to the other input / output terminal. Thus, this circuit operates as a band rejection filter having a frequency band near the resonance frequency as a stop band.

  In the filter according to the fifth embodiment, the short-circuit means 8a, 8b, and 8c similar to those of the fourth embodiment are applied as the short-circuit means for the resonators 15a, 15b, and 15c. For this reason, the fluctuation | variation of the resonant frequency resulting from the position shift of the through hole 4 can be suppressed very small. FIG. 18 shows the characteristics (calculated values) of this filter. Information on design conditions and dielectric substrate is shown in FIG. A filter is configured using a substrate having a dielectric constant of 10 in the Ku band (13 GHz band), and the interval between the stop band and the pass band is made slightly less than 3%. In FIG. 18, three characteristics are overlapped when through-hole position shifts of 0 μm, −50 μm, and +50 μm are given in the y direction of FIG. 16, but the variation in characteristics is extremely small.

  On the other hand, FIG. 19 shows frequency characteristics of a filter using a conventional short-circuit means under the same design conditions. The parameter is the through-hole position deviation as in FIG. As can be seen from this result, it can be seen that in the filter using the conventional short-circuit means, the stop band fluctuates by 2% or more, and there is no feasibility at all. The band fluctuation seen in FIG. 19 is caused by the fact that the ratio of the positional deviation amount of 50 μm to the quarter wavelength (considering wavelength shortening) which is the physical dimension of the resonator at the center frequency is about 2%. That is, it can be seen that the conventional short-circuit means is practically impossible even if a filter having the specifications shown in FIG. 18 is realized using a dielectric substrate having a relative dielectric constant of about 10. As described above, the filter according to the fifth embodiment makes it possible to realize a filter that has a narrow interval between a band in which the microwaves are desired to be suppressed and a band in which the microwaves are desired to pass, which is difficult to realize in the past.

  In the above description, the band rejection filter using the quarter wavelength resonator has been described. However, the impedance configuration circuit and other high-frequency circuits may be used as long as the configuration of the resonator is not a quarter wavelength and includes a short-circuit means. Needless to say, a similar effect can be expected with either of these methods. In addition, the circuit form of the filter is not limited to the band rejection filter, and any circuit having a short-circuit means, such as a band-pass filter using a quarter-wave resonator, a high-pass filter configured using a tip short-circuit stub, etc. A similar effect can be expected with a filter. In addition, not only the microstrip line but also other planar circuit type lines such as a triplate line can be used to achieve the same effect. The dielectric substrate may be any one from a single layer substrate to a multilayer substrate.

  Therefore, according to the fifth embodiment, the short-circuited stub, the resonator, or the filter can be configured by using any one of the short-circuit means of the first to fourth embodiments. There is. In addition, there is an effect that it is possible to realize a filter having an electrical characteristic that is difficult to realize by using the conventional short-circuiting means, such as when a band to suppress the passage of microwaves is close to a band to be passed. .

It is a top view of the tip short circuit stub concerning Embodiment 1 of this invention. It is sectional drawing in the surface containing the through hole of the front-end | tip short circuit stub which concerns on Embodiment 1 of this invention. It is the figure explaining the exploded view and equivalent circuit of the front-end | tip short circuit stub which concern on Embodiment 1 of this invention. It is a figure for demonstrating the operation | movement principle of the short circuit means which concerns on Embodiment 1 of this invention, and is a figure explaining replacing C section in FIG. 3 with the transmission line with a short end short circuit. FIG. 3 is a diagram illustrating a top view of a circuit when an x-direction through-hole position shift occurs in the tip short-circuited stub according to Embodiment 1 of the present invention and an equivalent circuit thereof. FIG. 3 is a top view of a circuit when a through-hole position shift in the −x direction occurs in the tip short-circuited stub according to Embodiment 1 of the present invention, and a diagram illustrating an equivalent circuit thereof. It is a graph which shows the solution at the time of solving Formula (3) on a certain condition. It is an figure which shows the electrical effect and calculation result of the short circuit means which concern on Embodiment 1 of this invention, and shows the fluctuation | variation of the reflection phase of a short circuit means when a through-hole position shift arises. It is a figure which shows the fluctuation | variation of a reflection phase when a through-hole position shift arises in the conventional short circuit means. It is a top view of the tip short circuit stub using the short circuit means concerning Embodiment 2 of this invention. It is an equivalent circuit schematic of the tip short circuit stub concerning Embodiment 2 of this invention. It is a top view of the tip short circuit stub using the short circuit means concerning Embodiment 3 of this invention. It is an equivalent circuit schematic of the tip short circuit stub concerning Embodiment 3 of this invention. It is a top view of the tip short circuit stub using the short circuit means concerning Embodiment 4 of this invention. It is an equivalent circuit schematic of the tip short circuit stub concerning Embodiment 4 of this invention. It is a top view of the filter comprised with the (lambda) / 4 resonator using the short circuit means based on Embodiment 5 of this invention. It is an equivalent circuit schematic of the filter concerning Embodiment 5 of this invention. It is a figure which shows the calculation result of the characteristic of the filter which concerns on Embodiment 5 of this invention. It is a figure which shows the frequency characteristic of the filter using the conventional short circuit means on the same design conditions as FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Dielectric board | substrate, 2 Signal conductor (strip conductor), 3 Ground conductor, 4 Short-circuit conductor (through hole), 5 Tip short-circuit stub, 6 Main line, 7 Input / output terminal, 8 Short-circuit means, 9 Reference plane, 10 Connection line , 11 Coupling conductor, 12 Connection line, 15 Resonator, 14 Relay line.

Claims (7)

A four-terminal circuit coupling line in which two transmission lines are arranged substantially in parallel and electromagnetically coupled to each other, a connection line connecting the two transmission lines, and a short-circuit conductor,
Two terminals adjacent on one side of the coupling line are electrically connected by the connection line, and one of the two terminals adjacent on the other side is connected to the ground conductor by the short-circuit conductor. Short-circuit means for short-circuiting and using the remaining terminals as input / output terminals for connection to an external circuit. Two short-circuit means having the same configuration as the short-circuit means according to claim 1, and two relay lines composed of transmission lines having substantially the same electrical length,
The two short-circuit means are arranged so that both coupled lines are substantially parallel, and one end of the relay line is connected to the input / output terminals of the two short-circuit means, and the other end of the relay line is electrically connected. Short-circuiting means, which are connected to each other and used as input / output terminals for connecting the connection location to the external circuit. A six-terminal circuit coupling line in which three transmission lines are arranged substantially in parallel and electromagnetically coupled to each other, a connection line connecting the three transmission lines, a short-circuit conductor, and a transmission line having substantially the same electrical length. Comprising two relay lines,
The three terminals adjacent on one side of the coupled line are electrically connected by the connection line, and one of the three terminals adjacent on the other side is connected to the ground conductor by the short-circuit conductor. For connecting one end of the relay line to each of the remaining two terminals on both sides, electrically connecting the other end of the two relay lines, and connecting the connection location with the external circuit Short-circuit means as input / output terminals. A six-terminal circuit coupling line in which three transmission lines are arranged substantially in parallel and electromagnetically coupled to each other, a connection line connecting the three transmission lines, and two short-circuit conductors,
The three terminals adjacent on one side of the coupling line are electrically connected by the connection line, and among the three terminals adjacent on the other side, each of the two terminals on both sides is grounded with a short conductor. A short-circuit means that uses the center terminal as the input / output terminal.   A tip short-circuit stub comprising the short-circuit means according to claim 1.   A resonator comprising the short-circuit means according to claim 1.   A high frequency filter comprising the short-circuit means according to any one of claims 1 to 4.

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