JPH0322602A - Dielectric oscillator - Google Patents

Abstract

PURPOSE:To suppress the fluctuation of an oscillated frequency with respect to a change in ambient temperature by using a bimetal made of two kinds of different kinds of metallic plates having a different thermal expansion rate for a frequency adjustment plate and changing a mean value of distances between a dielectric resonator and its frequency adjustment plate in response to a change in the ambient temperature. CONSTITUTION:A frequency adjustment plate 15 to adjust the oscillating frequency of a dielectric oscillator is a bimetal formed by joining two kinds of different metal plates 15a, 15b having different expansion coefficients alpha1, alpha2 and the coefficients alpha1, alpha2 have a relation of alpha1<alpha2. When the ambient temperature rises, since the frequency adjustment plate 15 is projected with respect to the dielectric resonator 8, the means value of the gap between the frequency adjustment plate 15 and the dielectric resonator 8 is increased as Ha. When the ambient temperature decreased, since the frequency adjustment plate 15 is recessed with respect to the dielectric resonator 8, the means value of the gap is decreased as Hb. Moreover, the coefficients alpha1, beta2 are selected such that the mean value of the gap between the dielectric resonator 8 and the frequency adjustment plate 15 corresponds to the fluctuation of the oscillated frequency in response to the change in the ambient temperature.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a dielectric oscillator as a microwave oscillator used in satellite broadcasting receivers, etc. This relates to a dielectric oscillator that suppresses fluctuations and stabilizes its oscillation frequency. [Conventional Example] Conventionally, this type of dielectric oscillator uses, for example, the oscillation circuit shown in Fig. 4. In this figure, a field effect transistor (F'E1゛)
One end of a microstrip line 2 is connected to the gate G of 1, and one end of a λ/4 open stub 3 for drain grounding and a λl4 line 4 for bias are connected to the drain D of the microstrip line 2.
Its source S is connected to one end of a λl4 short stub 5 for DC bias and to the input terminal of a matching circuit 6. The above microstrip line 2
A terminating resistor 7 is connected to the other end, and a cylindrical dielectric resonator 8 is provided near the microstrip line 2. The other end of the above line 2 has a λ for bias.
One end of the 74 line 9 and one end of the bias resistor IO are connected, and power is supplied to the oscillation circuit via the bias resistor 10. A signal of the oscillation frequency in the oscillation circuit is outputted via the matching circuit 6. Further, as shown in FIG. 5, the oscillation circuit is connected to the substrate (
The board is mounted on a dielectric (conductor) 11, and this board is enclosed within a shield case (conductor) 12. A movable frequency adjustment plate 13 is provided in the shield case l2 near the dielectric resonator 8. Therefore, the frequency adjustment plate l
3 has a male screw 14 attached to it, while the shield case 1
1 is provided with a female thread that fits with the male thread 14, and by rotating the male thread 14, the frequency adjustment plate 1
3 and the dielectric resonator 8 can be changed. In the dielectric oscillator having the above configuration, when power is applied to the oscillation circuit, an oscillation output with a specific frequency corresponding to the shape of the dielectric resonator 8 is obtained from the output matching circuit. The oscillation frequency can be changed to a predetermined value by changing the shape of the dielectric resonator 8, for example by cutting it. Further, by changing the distance H between the M electric resonator 8 and the frequency adjustment plate 13, the oscillation frequency can be finely adjusted. Such dielectric oscillators are used in high-frequency equipment such as satellite broadcasting receivers because they can obtain high Q values for microwaves and millimeter waves. [Problem W to be Solved by the Invention] Incidentally, in the dielectric oscillator described above, it is known that the oscillation frequency changes due to a change in the distance H between the dielectric resonator 8 and the frequency adjustment plate l3. That is, as shown in the curve in Figure 6, as the interval H increases, the oscillation frequency decreases, and conversely, as the interval H decreases, the oscillation frequency decreases.
The oscillation frequency increases. Therefore, when the ambient temperature changes, the dielectric substrate 1l bends due to the coefficient of thermal expansion, the shield case 12, the frequency adjustment plate 13, and the male screw l4 expand, and the distance between the dielectric resonator 8 and the frequency adjustment plate 13 increases. There is also a problem in that the oscillation frequency fluctuates due to the dielectric resonator 8 being deformed or the dielectric constant changing due to the temperature coefficient. This invention was made in view of the above problems, and its purpose is to provide a dielectric oscillator that can suppress fluctuations in oscillation frequency and stabilize the oscillation frequency in response to temperature changes. be. [Means for Solving the Problems] In order to achieve the above object, the present invention provides an oscillation circuit in which a dielectric resonator, a microstrip line, etc. are mounted on a substrate, and an oscillation circuit that is movable near the dielectric resonator. In a dielectric oscillator in which a metal frequency adjustment plate is enclosed in a shield case and the frequency of the dielectric resonator is adjusted by moving the frequency adjustment plate, the frequency adjustment plate is made of two types of metal plates with different coefficients of thermal expansion. The main idea is that the average distance between this bimetal and the dielectric resonator is changed according to changes in the ambient temperature. [Function] With the above configuration, when the ambient temperature changes, the bimetallic frequency adjustment plate deforms into a white or concave shape relative to the dielectric resonator. Then, the average value of the distance between the dielectric resonator and the frequency adjustment plate becomes smaller or larger than that distance. At this time, if the above temperature rises, the male screws that direct the shield case and frequency adjustment plate will expand, and the dielectric resonator will deform even slightly, causing the oscillation frequency of the dielectric oscillator to increase. but,
The frequency adjustment plate has a convex shape with respect to the dielectric resonator,
Since the average value of the above intervals becomes larger, the increase in the oscillation frequency is suppressed. On the other hand, when the temperature decreases, the frequency adjustment plate acts in the opposite direction, and the average value of the intervals becomes smaller, thereby suppressing the drop in the oscillation frequency of the dielectric oscillator. [Examples] Examples of the present invention will be explained below based on the drawings. In addition, in FIGS. 1 to 3, the same parts as in FIG. 5 are given the same reference numerals, and redundant explanation will be omitted. In FIG. 1, the frequency adjustment plate 15 for adjusting the oscillation frequency of the dielectric oscillator is made of two different metal plates 15a. For example, the expansion coefficient of the metal plate 15a is α, and the expansion coefficient of the metal plate 15b is α2. Note that these expansion coefficients α1 and α3 are α1〈α
There is a relationship of 3. That is, as shown in FIGS. 2 and 3, when the ambient temperature rises, the frequency adjustment plate 15 becomes convex with respect to the dielectric resonator 8, so that the frequency adjustment plate 15 and the dielectric resonance The average value of the distance from child 8 becomes thick as Ha. Furthermore, when the ambient temperature drops, the frequency adjustment plate 15 becomes concave with respect to the dielectric resonator 8, so that the average value of the interval becomes small to Hb. In addition, the expansion coefficients α, α2 are values at which the average value of the distance between the dielectric resonator 8 and the frequency adjustment plate l5 changes according to the change in the oscillation frequency according to changes in the ambient temperature. It has become. To explain in more detail, it is assumed that the oscillation frequency of the dielectric oscillator is set to a predetermined value and has already been adjusted. Then, due to a change in the ambient temperature, for example an increase,
The oscillation frequency of the dielectric oscillator increases. However, as shown in FIG. 2, in the present invention, the average value of the distance between the dielectric resonator 8 and the frequency adjustment plate 15 becomes a large value Ha (>H) according to the temperature change. This causes the frequency adjustment plate l5 to warp upward (on the paper). Moreover, since the difference between the interval H and the average value Ha corresponds to the variation in the oscillation frequency, the oscillation frequency is lowered by the variation. Therefore, as shown in FIG. 6, when the oscillation frequency a increases to 81 due to a change in the ambient temperature, the average distance between the dielectric resonator 8 and the frequency adjustment plate 15 increases depending on the change in temperature. This is because the value becomes as large as Ha. That is, the average value of the dielectric resonator 8 and the frequency adjustment plate l5 becomes Ha, thereby suppressing an increase in the oscillation frequency. Furthermore, as the ambient temperature decreases, as shown in FIG. 3, the average value of the distance between the dielectric resonance 18 and the frequency adjustment plate 15 changes to Hb (<H) in accordance with the temperature change. This causes the frequency adjustment plate 15 to warp downward (on the plane of the paper). Furthermore, since the difference between the interval H and the average value Ha corresponds to the variation in the oscillation frequency, the oscillation frequency is increased by the variation. That is, the average value of the distance between the dielectric resonator 8 and the frequency adjustment plate 15 decreases to Hb as the ambient temperature changes, so that a drop in the oscillation frequency is suppressed. As described above, when the ambient temperature changes, the dielectric substrate 1l bends due to the coefficient of thermal expansion, the shield case 12, the frequency adjustment plate 13, and the male screw l4 expand, and the dielectric resonator 8 and the frequency adjustment plate 13 expand. Even if the distance between the dielectric resonator 8 and the frequency adjustment plate l5 changes, and even if the dielectric resonator 8 is slightly deformed due to the temperature coefficient or the dielectric constant changes, the distance between the dielectric resonator 8 and the frequency adjustment plate l5 changes, and the dielectric resonator Since the average value of the distance between the frequency adjustment plate 15 and the frequency adjusting plate 15 is changed by the amount of frequency variation corresponding to the temperature change, variation in the oscillation frequency of the dielectric oscillator is suppressed. In the above embodiment, the oscillation frequency of the dielectric oscillator increases as the temperature increases and decreases as the temperature decreases, but in the case of a dielectric oscillator with a reverse action, two types of metal plates 1
The values of the thermal expansion coefficients of 5a and 15b can be reversed. Also,
The shape of the frequency adjustment plate 15 is not limited to the same cross-sectional shape as the dielectric resonator 8, and may be, for example, a rectangular plate. [Effects of the Invention] As explained above, the dielectric oscillator of the present invention According to the above, a bimetal consisting of two types of dissimilar metal plates with different coefficients of thermal expansion is used for the frequency adjustment plate that adjusts the oscillation frequency, and a dielectric resonant element and its frequency adjustment plate are adjusted according to changes in ambient temperature. Since the average value of the intervals is changed, fluctuations in the oscillation frequency can be suppressed when the ambient temperature changes, and the oscillation frequency can be stabilized.

[Brief explanation of the drawing]

FIG. 1 is a schematic side sectional view of a dielectric oscillator showing an embodiment of the present invention, FIGS. 2 and 3 are operation diagrams for explaining the operation of the dielectric oscillator, and FIG. 4 is a dielectric oscillator. A schematic block diagram of the oscillator, FIG. 5 is a schematic side sectional view of a conventional dielectric excavator, and FIG. 6 shows the change in oscillation frequency with respect to the distance between the dielectric resonator and the frequency adjustment plate of the dielectric oscillator. This is a characteristic diagram. In the figure, 8 is a dielectric resonator, 11 is a substrate (dielectric), and 12 is a dielectric resonator.
is a shield case (conductor), 14 is a male screw, 15 is a frequency adjustment plate (bimetal), 15a is a metal plate (expansion coefficient αt), and tsb is a metal plate (expansion coefficient α2; 〉α1).

Claims (2)

[Claims] (1) An oscillation circuit in which a dielectric resonator, a microstrip line, etc. are mounted on a substrate, a movable metal frequency adjustment plate is enclosed in a shield case near the dielectric resonator, and the frequency adjustment plate is moved. In a dielectric oscillator that adjusts the frequency of the dielectric resonator by, the frequency adjustment plate is a bimetal made by joining two types of metal plates with different coefficients of thermal expansion, and the average distance between the bimetal and the dielectric resonator is A dielectric oscillator characterized in that the oscillator changes according to changes in ambient temperature. (2) The dielectric oscillator according to claim 1, wherein the coefficient of thermal expansion of the metal plate closer to the dielectric resonator is greater than the coefficient of expansion of the other metal plate among the two types of metal plates.