JPS61136302A - Dielectric resonator - Google Patents

Abstract

PURPOSE:To widen an adjustment range of a resonance frequency by providing a dielectric material which can be taken in and out, on a notch part of an internal dielectric column for constituting a TM010 mode dielectric resonator. CONSTITUTION:A columnar dielectric 12 is contained in a vessel constituted of a cylindrical dielectric case 24, a cover 26 and a bottom plate 28. Also, in this vessel, an electrode 38 is formed continuously, and input/output terminals 34, 36 are provided on the bottom plate 28. A dielectric resonator constituted in this way is resonated by a TM010 mode or its deformed mode. On the side face of the columnar dielectric 12 for governing this resonance mode, a notch 40 is provided in the diameter direction, and also a dielectric plate 42 is connected to a tuning supporting rod 44 and provided so that it can be taken in and out against the notch 40. A resonance of the dielectric resonator is adjusted by rotating the supporting rod 44 and taking in and out the dielectric plate 42 to and from the notch 40, its adjustment range is wide, and also it can be adjusted without lowering remarkably Q of no-load.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a dielectric resonator, and in particular to a TMOt constructed by arranging a columnar dielectric within a metal case or an external electrode.
This invention relates to a dielectric resonator using o mode or its modified mode.

(Prior art) Structures for adjusting the resonant frequency of a dielectric resonator in TMOIO mode or its modified mode are disclosed in, for example, Utility Model Application Publication No. 59-88908 and Utility Model Application Publication No. 59-88-
It is disclosed in JP-A No. 119611 and the like. In both of the two cited publications, another dielectric material is inserted into the cavity and then displaced.

As is well known, when a dielectric material is placed in a cavity, its resonant frequency changes based on perturbation theory of the cavity's resonance properties. However, in all conventional devices, electric field leakage occurs, and when considering Qo (no-load Q), it is not possible to increase the variation range (Δfo) of the resonant frequency very much. This is because when ΔfO is increased, Qo is significantly lowered. Therefore, in this prior art, the rate of change (, II f o/ f
o) can only be made less than 0°5%, and if it is made larger than that, the QO will be reduced by more than 10%.

Therefore, it is conceivable to use a variable capacitor as shown in FIG. Dielectric resonator 10 shown in FIG.
includes a columnar dielectric 12 and a metal case 14 surrounding it, as is well known. Then, an electrode 16 is formed on the side surface of the columnar dielectric 12, and a through hole 18 is formed on the upper surface of the metal case 14. Then, a lead wire from one electrode of the variable capacitor 20 is connected to the electrode 16 through the through hole 18, and a lead wire from the other electrode is connected to the metal case 14. At this time, a bushing 22 made of rubber, for example, is fitted into the through hole 18, thereby preventing the lead wire from coming into contact with the metal case 14.

A displacement current is generated in the columnar dielectric 12, and an actual current flows in the metal case 14. However, when the variable capacitor 20 is connected as shown in FIG. 8, a current loop is also formed that flows from the connection electrode 16 formed on the side surface of the columnar dielectric body 12 through the variable capacitor 20 to the external electrode, that is, the metal case 14.

Therefore, the equivalent circuit becomes as shown in FIG.

In FIG. 9, capacitance C1 is the capacitance above the electrode 16, and capacitance C2 is the capacitance formed below the electrode 16. Therefore, the capacitance C3 caused by the variable capacitor 20 is connected in parallel with the capacitance C1. In FIG. 9, the inductance is formed by the gold case or the external electrode 14.

Referring to the equivalent circuit in FIG. 9, the composite capacitance C' is:
Ignoring the inductance due to the lead wire of the variable capacitor 20, it is given by the following equation (1).

Here, A is a coefficient that depends on the area and position of the electrode [6 (FIG. 8). And the resonant frequency f in this circuit
o is given by the following equation (2).

fo=1/2πf] (2) In equation (1), the combined capacitance C' changes depending on the change in the capacitance C3 of the variable capacitor 20. Therefore, when the capacitance C3 of the variable capacitor 20 changes, the resonance frequency fo given by equation (2) also changes. It will be understood from this that using the variable capacitor 20 changes the resonant frequency fo.

(Problems to be solved by the invention) In addition, when using a variable capacitor in this way,
There are the following problems that need to be solved. Since the Q of the variable capacitor itself is not very large, by connecting it, the Qo of the entire dielectric resonator also decreases by, for example, 5 to 10%. Furthermore, although it depends on the size of the variation range of the capacitance of the variable capacitor, Δfo may still not be large enough, and if the dielectric resonator is used in a circuit to which high voltage is applied, the voltage applied to the variable capacitor 20 Therefore, the main purpose of this invention is to change the resonant frequency over a wider range without significantly reducing the QO. An object of the present invention is to provide a dielectric resonator that can be used.

(Means for Solving the Problems) The present invention provides a dielectric resonator in which a notch is formed in a part of an internal dielectric surrounded by an external electrode, and a dielectric member is provided in and out of the notch. It is.

(Function) In a dielectric resonator, the electric field is strong in the internal dielectric part, that is, the central part, and the dielectric member is moved in and out of the notch formed in the internal dielectric, so perturbation theory does not apply. The range of change in the base frequency increases. At the same time, since the dielectric member is simply moved in and out, current concentration does not occur, and therefore, the Joule loss that causes a decrease in Qo is also relatively small, so the decrease in Qo is also small.

(Effect of the invention) According to this invention, the Q
A dielectric resonator with a large change width ΔrO in resonance frequency can be obtained without a significant decrease in O.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

(Embodiment) FIG. 1 is an illustrative front sectional view showing an embodiment of the present invention. In the dielectric resonator 10, the columnar dielectric 12 is housed in a cylindrical dielectric case 24, and a lid 26 and a bottom plate made of the same dielectric material are provided at the upper and lower ends of the dielectric case 24, respectively. 28 is attached. The bottom plate 28 is formed with through holes 34 and 36 through which antenna terminals 30 and 32 for coupling input and output are inserted. However, in addition to such antenna coupling (electric field coupling), various methods such as inductive coupling and capacitive coupling can be considered for input/output coupling.

Further, electrodes 38 are continuously formed on the dielectric case 24, the lid 26, and the bottom plate 28.

This electrode 38 serves as the conventional metal case 14 shown in FIG. Therefore, in addition to using a dielectric case and electrodes formed thereon as in this embodiment, it is also possible to use a metal case as shown in FIG. 8 as the external electrode.

A notch 40 cut in the radial direction is formed at a position in the height direction of the columnar dielectric body 12.

A dielectric plate 42, the shape of which can be clearly seen from FIG. 2 in particular, is provided in and out of this notch 40. Note that the thickness of the cutout 40 is selected to be larger than the thickness of the dielectric plate 42 to some extent, so that the dielectric plate 42 is prevented from coming into contact with the portion of the columnar dielectric 12 that defines the cutout, thereby ensuring stability. It has become a thing.

Further, a support rod 44 for tuning is connected to the dielectric plate 42, and a through hole 46 is formed in the lid 26 in order to guide the support rod 44 to the outside. Therefore, by turning this support rod 44 from the outside as shown by the arrow, the dielectric plate 42 can be moved in and out of the notch 40.

Preferably, the dielectric plate 42 is made of a material with a high dielectric constant like the columnar dielectrics 12 and the dielectric case 24, and the support rod 44 is made of a material with a small dielectric constant. This is to suppress current concentration in the support rod 44 as much as possible.

According to the results of experiments conducted by the inventor, when the dielectric plate 42 is inserted into the notch 40 as shown in FIG. 2, fo = 1054.6 MHz and Qo = 5620; As shown, when the support rod 44 is rotated and the dielectric plate 42 is taken out from the notch 40, fo = 1078.2 MHz and Qo = 5530.
Met. Therefore, the rate of change of the resonant frequency fo (=Δ
fo/fo) is 2.2%, and the rate of change in no-load Q (=
ΔQ o /Q o ) was -1.6%.

Compared to what is disclosed in the publication cited above, the rate of change in resonance frequency was approximately four times as high, and the rate of change in QO was approximately 1/6. Also, these rates of change are
It is also improved compared to the one using the variable capacitor shown in the figure.

Next, the reason why the frequency can be changed in the embodiment of FIG. 1 will be explained in detail.

First, the following equation (3) is an approximate solution representing perturbation theory.

However, in this equation (3), ε and E represent the permittivity and electric field of each part in the initial state,
Please note that it is considered as the sum of these.

In equation (3), Δε represents the change in ε of each part, and E
' indicates the electric field after perturbation of each part, and El indicates the complex conjugate electric field of E. Then, by rotating the support rod 44 and moving the dielectric plate 42 in and out of the notch 40, ε and E' are changed. Therefore, (3
), ω (=2πf) changes.

Such frequency changes will be explained using equivalent circuits shown in FIGS. 4 and 5. In the FIG. 1 embodiment,
It is considered that capacitance is formed as shown in FIG. Therefore, the embodiment of FIG. 1 can be expressed as an equivalent circuit shown in FIG. Here, C1l is the internal dielectric 12 above the notch 40, C12 is the part of the notch 40, C13 is the dielectric plate 42, and C14 is the notch 40.
is the capacitance formed in the internal dielectric 12 from 0 to below, respectively.

The electric field distribution of the TMo+o mode or its modified mode is strong at the center and becomes weaker toward the periphery. Therefore, most of the lines of electric force pass through the columnar dielectric, and few lines of force pass through the air around it. Therefore, approximately, the capacitance C13 in FIG. 5 is determined by the size of the overlapping portion of the columnar dielectric 12 and the dielectric plate 42. The composite capacitance C' in FIG. 5 is given by the following equation (4).

C' C1l C12+ C13C14... (
4) In the state shown in FIG. 3, the capacitance C13 formed by the dielectric plate is small;
As the dielectric plate 42 is inserted into the notch 40,
The dielectric capacitance C13 increases. That is, the capacitance C13 changes depending on the amount of insertion and removal of the dielectric plate 42, and therefore the combined capacitance C' changes. Therefore, the resonant frequency fo given by equation (2) above also changes.

By the way, the larger the capacitance C13 is, the greater the combined capacitance C
' increases, and the resonant frequency fo decreases.

In addition, in the configuration like the embodiment shown in FIG.
As can be seen from the figure, all of the dielectric plate 42 comes out of the notch 40 by only rotating the support rod 44 by about 70 degrees. That is, since the support rod 44 and the dielectric plate 42 are directly connected, there is a problem in that it is difficult to make delicate frequency adjustments.

Therefore, in order to effectively use the entire rotation range (360°) of the support rod 44 by changing the amount of rotation of the support rod and the rate of change in frequency, the rotation of the support rod 44 may be geared down, for example. It may also be communicated. To this end, the support rod 44 must be connected to such a gear portion (not shown).
It will be connected to the dielectric plate 42 through.

Furthermore, since using a gear mechanism would complicate the configuration, in order to avoid using such a gear mechanism, the dielectric plate 42
The planar shape may be devised, for example, as shown in FIG. By using the dielectric plate 42 having the shape shown in FIG. 6, it is possible to effectively utilize the entire rotation range of the support rod 44 without using a gear mechanism. The planar shape of 42 is arbitrary.

In addition, in the above-mentioned embodiments, the dielectric plate 4
A rotatable support rod 44 was used to move the 2 into and out of the notch 40. However, the dielectric plate 4
For a displacement of 2, a configuration as shown in FIG. 7 is also available.

In FIG. 7(A), the dielectric plate 42 is moved in and out of the notch 4o by extending the support rod 44 from the side surface of the dielectric case 24 and moving it in the direction of the arrow. In addition, the support rod 44 shown in FIG. 7(B) is similarly extended to the side of the dielectric case 24, but the direction in which it is moved is different from that shown in FIG. 7(A). .

[Brief explanation of the drawing]

FIG. 1 is an illustrative front cross-sectional view showing one embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line ■--■ in FIG. 1. FIG. 3 is a sectional view corresponding to FIG. 2 showing a state in which the dielectric plate is moved. FIG. 4 is a diagram showing the capacitance of the embodiment of FIG. 1. FIG. 5 is an equivalent circuit diagram of the embodiment shown in FIG. FIG. 6 is an illustrative cross-sectional view showing a modification of the dielectric plate. FIG. 7(A) and FIG. 7(B) are cross-sectional views showing different configurations for moving the dielectric plate in and out of the notch. FIG. 8 is an illustrative diagram showing an example of using a conventional variable capacitor, which is the background of the present invention. FIG. 9 is an equivalent circuit diagram of FIG. 8. In the figure, 10 is a dielectric resonator, 12 is a columnar dielectric,
14 is a metal case, 38 is an external electrode, 40 is a notch, 42
indicates a dielectric plate, and 44 indicates a support rod. Patent applicant Murata Manufacturing Co., Ltd. Agent Patent attorney Yama 1) Yoshito (and 1 other person) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 rllJ (B) Figure 8 Figure 9 Proceedings (spontaneous) January 11, 1985 Patent Application No. 258305 2, Name of the invention Dielectric resonator 3, Relationship to the case of the person making the amendment Patent applicant address Nagaokakyo, Kyoto Prefecture 2-26-10, Ichitenjin Name (623) Murata Manufacturing Co., Ltd. Representative Village 1)
4th year of Showa, agent cloud 5401! Osaka (06) 764-
5443 (group) Spontaneous correction 7, ? ili positive content. Above

Claims (1)

[Claims] 1. A dielectric resonator using the TM_0_1_0 mode or a modified mode thereof, comprising: an inner dielectric, an outer electrode surrounding the inner dielectric, a notch formed on a side surface of the inner dielectric, and A dielectric resonator comprising a dielectric member that can be inserted into and taken out of the notch. 2. The dielectric resonator according to claim 1, further comprising displacement means that penetrates the external electrode and is connected to the dielectric member for displacing the dielectric member from the outside. 3. Claim 2, wherein the displacement means includes a rotating shaft.
Dielectric resonator as described in section. 4. The dielectric resonator according to claim 2, wherein the displacement means includes a linear motion member. 5. Claims 2 to 4, wherein the displacement means includes a shaft connected to the dielectric member, and the shaft is formed of a dielectric material having a lower dielectric constant than the dielectric member.
The dielectric resonator according to any of paragraphs.