JPS637684B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dielectric resonator that is small, inexpensive, and has high stability.

Conventionally, when a dielectric resonator element is electromagnetically coupled to a distributed constant circuit such as a microstrip line and used as a dielectric resonator circuit, as shown in FIG. It was fixed on an object support 12 and electromagnetically coupled to a stripline 14 provided on a substrate 13.
The approximate resonant frequency of this dielectric resonator circuit is determined by the dielectric constant and geometric dimensions of the dielectric resonator element 11, but since this dielectric resonator element 11 does not have a frequency variable function, the resonant frequency Fine adjustment was performed by setting the dimensions of the metal case 15, which has an electromagnetic field shielding effect, to an appropriate value and by varying the frequency adjustment screw 16. For this reason, it is necessary to provide a metal case 15 around the dielectric resonator element 11, which has the disadvantage of increasing the size of the resonator circuit. Furthermore, high dimensional accuracy is required to keep the central axes of the screw 16 and the dielectric resonator element 11 within a predetermined dimension, which has the disadvantage of increasing manufacturing costs. Moreover, if the dimensions of the metal case 15 are not set to appropriate values, an unnecessary mode will occur and desired electrical characteristics cannot be obtained. Furthermore, in this dielectric resonator circuit,
There was a drawback that the resonance frequency changed with temperature due to thermal expansion of the metal case 15.

The present invention has been made in view of the above-mentioned conventional drawbacks, and an object thereof is to provide a dielectric resonator that is small, inexpensive, and has high operational stability.

The details of the present invention will be explained below with reference to Examples.

FIG. 2 is a perspective view showing the configuration of an embodiment of the dielectric resonator of the present invention, in which 1 is a dielectric resonator element;
7 is an insulating plate, and 8 is a conductor layer formed on this insulating plate 7. The dielectric resonator element 1 has a relative dielectric constant of 40
It is composed of a block of ceramic such as barium titanate, which has a relatively large dielectric constant of ~100, and the dielectric constant and geometric dimensions of this element 1 determine the approximate resonant frequency of this dielectric resonator. do.
The insulating plate 7 is made of an insulating material such as quartz having a lower permittivity than the dielectric resonator element 1, and is ultimately connected to the element 1 via a bonding layer such as adhesive or low melting point glass.
is fixed to the top surface of the On the surface of this insulating plate 7,
The conductor layer 8 is formed by an appropriate method such as vapor deposition or plating. An example of a method for forming the conductor layer 8 is as follows:
First, a nichrome layer with a thickness of about 200 Å (20 nm) is vacuum-deposited on the surface of the insulating plate 7, and then a nichrome layer with a thickness of
An Au layer with a thickness of about 3000 Å is deposited, and finally an Au layer with a thickness of about 5 μm is formed on top of this by electrolytic plating. Note that the nichrome layer in this case functions as a base to increase the adhesion strength between the conductor layer 8 and the insulating plate 7, and the thickness of this layer is kept as small as possible to prevent a decrease in the Q of the resonator. Set.

In the dielectric resonator configured in this manner, the resonant frequency is approximately determined by the dielectric constant and geometric dimensions of the dielectric resonator element 1. At this time, most of the electromagnetic energy exists inside the dielectric resonator element 1 having a high dielectric constant, but a part of it leaks to the outside of the dielectric resonator element 1. The amount of electromagnetic energy leaking to the outside can be controlled by placing a conductor layer 8 near the dielectric resonator element 1 and changing the position of the conductor layer 8. The conductor layer 8 is for controlling leakage of electromagnetic energy,
The insulating plate 7 having a predetermined thickness functions as a spacer for holding the conductor layer 8 at a predetermined distance from the element 1. As the material for the insulating plate 7, a material with low high frequency loss such as quartz is desirable in order to increase the Q of this dielectric resonator. The amount of electromagnetic energy leaking to the outside of the dielectric resonator element 1 is determined by the insulating plate 7.
, that is, the position of the conductor layer 8. Therefore, in the dielectric resonator configured as shown in FIG.
It can be adjusted by changing the thickness.

Specifically, several types of insulating plates 7 with different thicknesses are prepared, and while observing the resonant frequency of the dielectric resonator in the circuit shown in Figure 3, the insulating plates 7 with an appropriate thickness are selected to obtain the desired resonant frequency. 7 is placed on the dielectric resonator element 1, and after selecting an insulating plate 7 having a thickness that provides the desired characteristics, the insulating plate 7 is mounted on the element 1 using an adhesive or the like.
It is possible to perform stepwise resonance frequency adjustment corresponding to the thickness of the material. By preparing the insulating plates 7 with a large number of thicknesses, the resonance frequency can be adjusted almost continuously. In this embodiment, the cross-sectional shapes of the dielectric resonator element 1 and the insulating plate 7 are circular, but the same effects can be obtained even with other shapes.

FIG. 4 is a perspective view showing the structure of another embodiment of the present invention. Elements in this figure labeled with the same reference numerals as in FIG. 2 are the same elements as those already explained in connection with FIG. 2, and a redundant explanation thereof will not be necessary. In this embodiment, the conductor layer 8
is formed not on the entire surface of the insulating plate 7 but only at its periphery. The amount of electromagnetic energy leaking to the outside of the dielectric resonator element 1 depends on the area of the conductor layer 8. Therefore, by incorporating this resonator into a circuit as shown in Figure 5 and removing an appropriate area of the conductor layer 8 by laser trimming or the like while observing the electrical characteristics, the dielectric layer 8 can be removed in accordance with the area. The amount of electromagnetic energy leaking to the outside from the body resonator element 1 can be adjusted, and as a result, the resonant frequency of this dielectric resonator can be set to a desired value. In this embodiment, the removed portion of the conductor layer 8 is circular, but
Similar actions and effects can be achieved with other shapes.

FIG. 6 shows a specific example of resonant frequency adjustment when the dielectric resonator circuit shown in FIG. 3 is constructed using the dielectric resonator shown in FIG. 2. The resonant frequency decreases as the thickness of the insulating plate increases. When the thickness of the insulating plate is changed from 0.5mm to 3mm,
The resonant frequency changes by about 10%. In addition, in Figure 6, the dimensions of the dielectric resonator element are 7 mm in diameter and 2.8 mm in thickness, and the dimensions are 11 mm in diameter using quartz as an insulating plate.
This is an example when it is set to mm.

FIG. 7 shows a specific example of resonant frequency adjustment when the dielectric resonator circuit shown in FIG. 5 is constructed using the dielectric resonator shown in FIG. 4. The resonant frequency decreases as the diameter of the portion where the conductor layer 8 is removed increases. In Fig. 7, the dimensions of the dielectric resonator element are 7 mm in diameter and 2.8 mm in thickness, and quartz is used as the insulating plate 7, and the dimensions are 7 mm in diameter and 2.8 mm in thickness.
This is an example when it is 0.5mm.

In the above embodiment, an insulating plate was attached to the top surface of the dielectric resonator element, but since the electromagnetic energy leaking around this element is almost isotropic, the surface to which the insulating plate should be attached is as described above. It is not limited to the top surface, but may be the side surface, or both the top surface and the side surface. Further, when the dielectric resonator element is hung and held, an insulating plate can be attached to the lower surface of the element.

Also, although we have explained an example of using quartz as an insulating plate, if it is a dielectric material with low loss and low dielectric constant,
Appropriate materials such as tetrafluoroethylene and ceramics, which are commercially available under trade names such as Teflon, can be used.

As explained in detail above, the present invention can reduce the electromagnetic energy leaking around the dielectric resonator element by installing a conductor with a selected area at a position selected by the thickness of the insulator near the dielectric resonator element. This configuration allows the resonant frequency of the dielectric resonator to be set to a desired value, eliminating the need for a metal case or frequency adjustment screws as in conventional dielectric resonant circuits. , it is possible to downsize the circuit and reduce manufacturing costs. In addition, there is no problem of unnecessary modes occurring due to inappropriate dimensions of the metal case, and there is no change in operating characteristics due to thermal expansion of the metal case, which has the advantage of extremely improved stability. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of the configuration of a conventional dielectric resonator circuit, FIG. 2 is a perspective view showing an embodiment of the dielectric resonator of the present invention, and FIG. 3 is a dielectric shown in FIG. FIG. 4 is a cross-sectional view showing an example of the configuration of a dielectric resonator circuit using a resonator, FIG. 4 is a perspective view showing another embodiment of the dielectric resonator of the present invention, and FIG. 5 is a dielectric resonance circuit shown in FIG. 6 is a characteristic diagram showing an example of the characteristics of the resonant circuit shown in Fig. 3, and Fig. 7 is an example of the characteristics of the resonant circuit shown in Fig. 5. Characteristic diagram showing. DESCRIPTION OF SYMBOLS 1, 11... Dielectric resonator element, 7... Insulator plate, 8... Conductor layer, 12... Insulator support base, 13...
Substrate, 14... Microstrip line, 15...
Metal case, 16...Screw for frequency fine adjustment.

Claims (1)

[Claims] 1 A dielectric resonator comprising a dielectric resonator element that is electromagnetically coupled to a distributed constant circuit to impart resonance characteristics to the distributed constant circuit, the dielectric resonator having at least one surface of the dielectric resonator element. is attached with an insulating plate having a predetermined thickness having a dielectric constant lower than that of the dielectric resonator element, and a surface of the insulating plate facing the surface in contact with the dielectric resonator element. A conductor layer having a predetermined area is formed on at least a portion of the insulating plate, and the predetermined thickness of the insulator plate and the predetermined area of the conductor layer are based on the dielectric constant and dimensions of the dielectric resonant element. A dielectric resonator, characterized in that the material is selected to determine the resonant frequency of the resonator.