Quadruple-mode resonator and quadruple-mode resonator filter

Abstract

Provided is a quadruple-mode resonator capable of having a reduced resonator height. In this quadruple-mode resonator 1, electromagnetic field energy is confined in an outer peripheral conductor 2 forming a rectangular parallelepiped having a height smaller than the length and width thereof. The quadruple-resonant modes are the four modes of TM120, TM210, TE101, and TE011, with the height direction as the propagation direction of electromagnetic waves. A cross-shaped conductor plane pattern 3 is horizontally disposed at the center portion of the outer peripheral conductor 2. Inter-TE mode coupling conductors 4 are provided that each have one end connected to a side surface of the outer peripheral conductor 2 and are disposed horizontally. TM / TE mode coupling conductors 5 are provided that each have two ends connected to the lower surface and a side surface of the outer peripheral conductor 2. Two electric field probe input / output terminals 6 are provided that are insulated from the outer peripheral conductor 2 and inserted into the outer peripheral conductor 2 through the upper surface thereof.

Description

Quadruple-mode resonators and quadruple-mode resonator filters

[0001] This invention relates to a quadruple-mode resonator and a quadruple-mode resonator filter used in microwave wireless communication equipment and the like.

[0002] In recent years, microwave wireless communication equipment that operates in the microwave band has been widely used. Microwave wireless communication equipment uses microwave filters that operate in the microwave band. Microwave filters are constructed by electrically coupling multiple resonators. In microwave filters, generally, one physical structure (e.g., cavity) corresponds to one electrical resonator, and N structures constitute an N-stage filter. In contrast, it has been conventionally proposed to use dual-mode, triple-mode, or quadruple-mode resonators that utilize multi-mode resonance, in which two, three, or four resonant modes are degenerated within a single cavity with nearly identical resonant frequencies.

[0003] For example, Patent Document 1 describes a quadruple-mode resonator in which four resonant modes are degenerated, in which two central conductors, one end of which is short-circuited and the other end of which is open, are arranged facing each other inside the cavity of a box-shaped outer electrode, and the resonant mode has four degenerated modes including two TEM modes and two TE modes. Patent Document 2 describes a configuration in which a rectangular parallelepiped dielectric core having multiple resonant modes such as TM01δ-x, -y, -z and TE01δ-x, -y, -z is arranged in the center of the cavity. Patent Document 3 describes a configuration in which a dielectric core consisting of a plate-shaped dielectric core portion for TM modes and a spherical dielectric core portion for TE modes that bulges asymmetrically in the vertical direction from there is arranged inside the cavity, and the resonant mode has multiple modes.

[0004] Japanese Patent Publication No. 2013-80992, Japanese Patent Publication No. Hei 11-145704, Japanese Patent Publication No. 2001-156511, Japanese Patent Publication No. 2007-290940

[0005] Incidentally, since devices such as microwave wireless communication equipment are generally constructed by mounting multiple components such as microwave filters on a substrate, it is desirable for the height of each individual component to be low. Furthermore, the resonator that makes up the microwave filter is often formed on a dielectric substrate made by stacking multiple thin dielectric sheets of LTCC (Low Temperature Co-Fired Ceramics) in the height direction, as shown in Figure 1 of Patent Document 4. In this case, it is extremely important that the resonator can be realized with a structure that keeps the height low.

[0006] However, in the configuration shown in Patent Document 1, the X and Y axes require lengths that allow for resonance in waveguide mode, and the Z axis (the axis direction of the two opposing central conductors) tends to be longer than the X and Y axes, making it difficult to keep the resonator height low regardless of which axis it is aligned with. Furthermore, in the configuration shown in Patent Document 2, the X, Y, and Z axes require lengths that allow for resonance in waveguide mode, making it fundamentally impossible to keep the resonator height low regardless of which axis it is aligned with. In addition, in the configuration shown in Patent Document 3, space is required around the dielectric core, the X and Y axes of the dielectric core require lengths that allow for resonance in waveguide mode, and the Z axis (vertical direction) of the dielectric core requires the length of the spherical TE mode dielectric core portion that constitutes it, making it difficult to keep the resonator height low regardless of which axis it is aligned with.

[0007] This invention has been made in view of the above circumstances, and its purpose is to provide a quadruple-mode resonator and a quadruple-mode resonator filter that can reduce the height of the resonator.

[0008] To achieve the above objective, the quadruple-mode resonator according to the embodiment of the present invention is a quadruple-mode resonator in which electromagnetic field energy is confined inside an outer conductor that forms a rectangular parallelepiped in which the height is shorter than the length and width, and the four resonant modes are TM120, TM210, TE101, and TE011 when the height direction is the direction of electromagnetic wave propagation.

[0009] The quadruple-mode resonator can be configured such that a cross-shaped conductor planar pattern is horizontally arranged in the center of the outer conductor.

[0010] The quadruple-mode resonator can be configured such that a cross-shaped conductor planar pattern is horizontally arranged in the center of the outer conductor, and a horizontally arranged intermode coupling conductor is provided, with one end connected to the side surface of the outer conductor.

[0011] The quadruple-mode resonator can be configured such that a cross-shaped conductor planar pattern is horizontally arranged in the center of the outer conductor, and TM / TE mode coupling conductors are provided with both ends connected to the lower surface and side or upper surface and side of the outer conductor.

[0012] The quadruple-mode resonator can be configured such that a cross-shaped conductor planar pattern is horizontally arranged in the center of the outer conductor, and input / output terminals for two electric field probes are provided, which are insulated from the outer conductor and inserted into the interior from the top or bottom surface.

[0013] The quadruple-mode resonator filter according to an embodiment of the present invention uses the aforementioned quadruple-mode resonator.

[0014] According to the quadruple-mode resonator and quadruple-mode resonator filter of the present invention, the height of the resonator can be reduced.

[0015] This is a perspective view showing a quadruple-mode resonator according to an embodiment of the present invention. This shows the same quadruple-mode resonator, with (a) being a plan view and (b) being a side view. This is a perspective view showing the configuration of a three-dimensional electromagnetic field simulation of the outer conductor of the same quadruple-mode resonator. This shows the electric field distribution of the resonant modes in the three-dimensional electromagnetic field simulation of the outer conductor of the same quadruple-mode resonator. This is a graph showing the resonant frequencies when the length and width are changed in the three-dimensional electromagnetic field simulation of the outer conductor of the same quadruple-mode resonator. This is a perspective view showing the configuration of a three-dimensional electromagnetic field simulation of a cross-shaped conductor planar pattern of the same quadruple-mode resonator. This is a graph showing the resonant frequencies when the length of the cross-shaped conductor planar pattern is changed in the three-dimensional electromagnetic field simulation of the cross-shaped conductor planar pattern of the same quadruple-mode resonator. This is a perspective view showing the configuration of a three-dimensional electromagnetic field simulation of the TE-mode coupling conductor of the same quadruple-mode resonator. This is a graph showing the degeneracy being lifted in the three-dimensional electromagnetic field simulation of the TE-mode coupling conductor of the same quadruple-mode resonator. This is a graph showing the four-stage filter characteristics of the same quadruple-mode resonator. This is a Smith chart showing the four-stage filter characteristics of the same quadruple-mode resonator.

[0016] Embodiments of the present invention will be described below with reference to the drawings. As shown in Figures 1 and 2, the quadruple-mode resonator 1 according to an embodiment of the present invention comprises an outer conductor 2, a cross-shaped conductor planar pattern 3, a TE-mode coupling conductor 4, a TM-TE mode coupling conductor 5, and two input / output terminals 6. The quadruple-mode resonator 1 can be used as a quadruple-mode resonator filter in a microwave filter operating in the microwave band. The quadruple-mode resonator 1 can also be formed on a dielectric substrate manufactured by stacking multiple thin dielectric sheets of LTCC (Low Temperature Co-fired Ceramics) in the height direction. The cross-shaped conductor planar pattern 3, the TE-mode coupling conductor 4, the TM-TE mode coupling conductor 5, and the two input / output terminals 6 (more specifically, the portion inside the outer conductor 2) can be formed from the metal pattern on the surface of the stacked dielectric sheets and / or the metal within the via holes. In Figures 1 and 2 (and Figures 3, 6, and 8 described later), the parts located inside the outer surface of the outer conductor 2 (including the inner wall surface of the outer conductor 2) and the components are shown with dashed lines.

[0017] First, let's explain the outer conductor 2. The outer conductor 2 forms a rectangular parallelepiped. By forming a rectangular parallelepiped, the outer conductor 2 forms a cavity structure. This rectangular parallelepiped has a square top and bottom surface, and its height is shorter than its length and width. For example, the outer conductor 2 can be formed by depositing (metallizing) a metal such as silver onto the outer surface of the LTCC dielectric substrate, which is a rectangular parallelepiped with the stacking direction as the height direction.

[0018] The outer conductor 2 can confine electromagnetic field energy internally, enabling resonance of multiple modes (waveguide modes). ０ , Y ０ , Z ０ If we consider the lengths in the X-axis direction (vertical length), Y-axis direction (horizontal length), and Z-axis direction (height) of the rectangular parallelepiped inside (inner wall) of the outer conductor 2, respectively (see Figure 1), then the theoretical formula for the resonant frequency of the waveguide mode is given by the following equation (1). Here, f ０ ε is the resonant frequency, c is the speed of light, and ε is the resonant frequency. ｒis the relative permittivity of the medium (e.g., LTCC) inside the rectangular parallelepiped, and m, n, and p are 0 or natural numbers representing the mode order, with at least two of them being non-zero.

[0019] For four modes out of a plurality of modes to become the resonance modes of the quadruple mode resonator 1, the four modes must not be degenerate at a specific resonance frequency, and moreover, the resonance frequencies of the modes other than the four degenerate modes (spurious modes) must be far from the specific resonance frequency.

[0020] As a result of the specific examination by the inventor of the present application using three-dimensional electromagnetic field simulation (simulation by the electromagnetic field analysis software HFSS of Cybernet Corporation), it is as follows. The outer conductor 2 is a rectangular parallelepiped as shown in FIG. 3, and the medium inside it has a relative permittivity ε ｒ of 7.4. X ０ , Y ０ , Z ０ are 10 mm, 10 mm, and 5 mm respectively. In this rectangular parallelepiped, considering the case where the propagation direction of the electromagnetic wave is in the Z-axis direction (the height direction of the rectangular parallelepiped), the resonance modes can be mode 1 shown in FIG. 4(a), mode 2 shown in FIG. 4(b), mode 3 shown in FIG. 4(c), mode 4 shown in FIG. 4(d), mode 5 shown in FIG. 4(e), and mode 6 shown in FIG. 4(f). FIGS. 4(a) to 4(f) show the electric field distributions respectively. Mode 1 is the TM110 mode. Mode 2 and mode 3 are the ones that appear on the diagonal line after the synthesis of the TM120 mode and the TM210 mode respectively. Mode 4 is the TE101 mode. Mode 5 is the TE011 mode. Mode 6 is the TM111 mode. The last three digits indicating each mode are the values of m, n, and p described above.

[0021] And FIG. 5 shows the results of the resonance frequencies when Z ０ is 5 mm and the lengths of X ０ , Y ０ are changed. Curve a in FIG. 5 is mode 1, curve b is the degenerate modes 2 and 3, curve c is the degenerate modes 4 and 5, and curve d is mode 6. X ０ , Y ０It can be seen that when the length is around 9.8 mm, four modes (mode 2, mode 3, mode 4, and mode 5) can be degenerated, and modes 1 and 6 become spurious modes.

[0022] Thus, the quadruple-mode resonator 1 is a rectangular parallelepiped with a low height for the outer conductor 2, and the four modes TM120, TM210, TE101, and TE011, when the direction of electromagnetic wave propagation is the Z-axis direction (the height direction of the rectangular parallelepiped), can be made into four resonant modes.

[0023] Next, the cross-shaped conductor planar pattern 3 will be described. By changing the length of the cross-shaped conductor planar pattern 3, the resonant frequencies of modes 4 and 5 (TE101 mode and TE011 mode) can be adjusted.

[0024] Figure 6 shows a rectangular parallelepiped with a cross-shaped conductive plane pattern 3 horizontally arranged in the center of the dielectric material within the outer conductor 2. ０ , Y ０ , Z ０ The dimensions are 10 mm, 10 mm, and 4.5 mm, respectively. The cross-shaped conductor planar pattern 3 has a width of 1 mm and a thickness of approximately 10 μm. Figure 7 shows the resonant frequencies obtained by changing the length of the cross-shaped conductor planar pattern 3 (shown as a solid line with arrows at both ends in Figure 6). Curves a, b, c, and d in Figure 7 are the same as those in Figure 5.

[0025] Figure 7 shows that when the length of the cross-shaped conductor planar pattern 3 is changed, the resonant frequencies of curve c (modes 4 and 5) (TE101 mode and TE011 mode) move up and down, while the resonant frequencies of curve b (modes 2 and 3) (TM120 mode and TM210 mode) remain almost unchanged. Therefore, by changing the length of the cross-shaped conductor planar pattern 3, the resonant frequencies of modes 4 and 5 (TE101 mode and TE011 mode) can be adjusted.

[0026] Furthermore, Figure 7 shows that when the length of the cross-shaped conductor planar pattern 3 is around 2.7 mm, four modes—modes 2, 3, 4, and 5—can be degenerated, and the resonant frequencies of the spurious mode of mode 1 and the spurious mode of mode 6 can be made to be very far apart. Therefore, the design of the quadruple-mode resonator 1 as a quadruple-mode resonator filter becomes even easier.

[0027] Next, the TE intermode coupling conductor 4 will be described. This conductor resolves the degeneracy of the two modes TE101 and TE011 so that their resonant frequencies are slightly different, allowing them to couple and transition. In the three-dimensional electromagnetic field simulation by the inventors of this application, the TE intermode coupling conductor 4 is positioned at approximately half the height of the outer conductor 2, with one end connected to the outer conductor 2 at an angle, and is arranged as a conductor strip in a horizontal diagonal direction, as shown in Figure 8. Note that the X of the outer conductor 2 ０ , Y ０ , Z ０ These dimensions are 9.8 mm, 9.8 mm, and 4.3 mm, respectively. In addition, a cross-shaped conductor planar pattern 3 is provided, with a width of 1 mm and a length of 2.7 mm.

[0028] As a result, the degeneracy of the two modes TE101 and TE011 is resolved due to the influence of the TE intermode coupling conductor 4, and the resonant frequencies become slightly different, at 11.681 GHz and 11.729 GHz, allowing us to obtain the characteristics of a two-stage filter as shown in Figure 9. Note that the configuration in Figure 8 differs from the configuration in Figure 1 for practical reasons in that there is one TE intermode coupling conductor 4 and two input / output terminals 6 are provided on two sides. This three-dimensional electromagnetic field simulation demonstrates that the degeneracy of the two modes TE101 and TE011 can be resolved, and the resonant frequency of the quadruple-mode resonator 1 is adjusted in conjunction with other parts or components.

[0029] Next, the TM-TE mode coupling conductor 5 will be described. This allows the TM120 mode (or TM210 mode) and the TE101 mode (or TE011 mode) to couple and transition with each other. In the three-dimensional electromagnetic field simulation by the inventor of the present application, as shown in FIG. 1, two TM-TE mode coupling conductors 5 are provided, and each is an elongated conductor that forms a loop shape with its both ends connected to the lower surface and the side surface of the outer conductor 2. The TM-TE mode coupling conductor 5 may be connected at both ends to the upper surface and the side surface of the outer conductor 2. Note that the X ０ , Y ０ , and Z ０ are 9.8 mm, 9.8 mm, and 4.3 mm respectively. Also, a cross-shaped conductor planar pattern 3 is provided, with a width of 1 mm and a length of 2.7 mm.

[0030] Then, a part of the magnetic field of the TM120 mode (or TM210 mode) and a part of the magnetic field of the TE101 mode (or TE011 mode) both intersect the TM-TE mode coupling conductor 5, generating an electric current in the TM-TE mode coupling conductor 5. Since the TM-TE mode coupling conductor 5 has a vertical part and a horizontal part, the electric current flowing through the TM-TE mode coupling conductor 5 can couple electromagnetic fields orthogonal to each other.

[0031] Next, the two input / output terminals 6 will be described. The two input / output terminals 6 can be two electric field probes that are insulated from the outer conductor 2 and inserted into it from the upper surface. The two input / output terminals 6 may be inserted into the outer conductor 2 from the lower surface.

[0032] Next, a characteristic example of a quadruple-mode resonator filter (four-stage filter) composed of the quadruple-mode resonator 1 shown in FIG. 1 will be described. In this three-dimensional electromagnetic field simulation, the outer conductor 2 is a rectangular parallelepiped, and its interior is a dielectric with a relative permittivity ε ｒ of 7.4. X ０ , Y ０ , and Z ０These dimensions are 9.8 mm, 9.8 mm, and 4.3 mm, respectively. The cross-shaped conductor planar pattern 3 is 2.90 mm long and 0.77 mm wide, and is horizontally positioned in the center of the dielectric. Two TE mode coupling conductors 4 are provided diagonally at approximately half the height of the outer conductor 2. Each is connected at one end to the outer conductor 2 at a corner and is a horizontally positioned conductor strip (metal pattern) with a length (diagonal length) of 1.90 mm, a width of 0.5 mm, and a thickness of 0.01 mm. Two TM / TE mode coupling conductors 5 are provided, each formed by connecting a portion (metal pattern) with a length of 1.15 mm, a width of 0.2 mm, and a thickness of 0.01 mm connected to the side surface of the outer conductor 2, and a portion (metal in the via hole) with a height of 1.17 mm and a radius of 0.1 mm connected to the bottom surface. The sides of the outer conductor 2 to which each of the two TM / TE mode coupling conductors 5 is connected are adjacent to each other and perpendicular to one another. Furthermore, the two input / output terminals 6 are located 2 mm inward from the center of the side opposite to the side where the two TM / TE mode coupling conductors 5 are connected, and are provided perpendicular to the upper surface of the outer conductor 2 with a length of 1.16 mm and a radius of 0.05 mm.

[0033] This quadruple-mode resonator 1 can transition between its four modes, TM120, TM210, TE101, and TE011, by coupling with any of the other modes, as described below. That is, for example, an input signal input to one input / output terminal 6 is electrically coupled to the TM120 mode, the TM120 mode is magnetically coupled to the TE101 mode by a TM / TE mode coupling conductor 5 on the side opposite to the input / output terminal 6, the TE101 mode and the TE011 mode are coupled by electric field perturbation by a TE mode coupling conductor 4, the TE011 mode and the TM210 mode are magnetically coupled by another TM / TE mode coupling conductor 5, and the output signal is obtained by electrically coupling the TM210 mode to the other input / output terminal 6. In this way, the quadruple-mode resonator 1 constitutes a four-stage filter.

[0034] As a result, in FIG. 10, the passband appears clearly in the transmission characteristic (S21), and attenuation occurs at other frequencies. Also, four valleys can be seen in the reflection characteristics (S11, S22). In FIG. 11, three small rotating rings can be seen. Therefore, it can be understood that the quadruple-mode resonator filter composed of the quadruple-mode resonator 1 has good four-stage filter characteristics.

[0035] As described above, the quadruple-mode resonator according to the embodiment of the present invention has been described. However, the present invention is not limited to those described in the above embodiments, and various design changes can be made within the scope of the matters described in the claims.

[0036] 1 Quadruple-mode resonator 2 Outer peripheral conductor 3 Cross-shaped conductor plane pattern 4 TE mode intercoupling conductor 5 TM / TE mode coupling conductor 6 Input / output terminal

Claims

1. A quadruple-mode resonator in which electromagnetic field energy is confined inside an outer conductor that forms a rectangular parallelepiped in which the height is shorter than the length and width, characterized in that the four resonant modes are TM120, TM210, TE101, and TE011 when the height direction is the direction of electromagnetic wave propagation.

2. A quadruple-mode resonator according to claim 1, characterized in that a cross-shaped conductor planar pattern is horizontally arranged in the center of the outer conductor.

3. A quadruple-mode resonator according to claim 2, characterized in that a horizontally arranged intermode coupling conductor is provided, with one end connected to the side surface of the outer conductor.

4. A quadruple-mode resonator according to claim 2, characterized in that a TM-TE mode coupling conductor is provided, the ends of which are connected to the lower surface and side surface or the upper surface and side surface of the outer conductor.

5. A quadruple-mode resonator according to claim 2, characterized in that it is provided with input and output terminals for two electric field probes inserted into the interior from the upper or lower surface, insulated from the outer conductor.

6. A quadruple-mode resonator filter characterized by using a quadruple-mode resonator as described in any one of claims 1 to 5.

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