JPS6147003B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a voltage controlled oscillator used in a modulator that requires a large modulation degree and a phase synchronized oscillator.

An oscillator using a dielectric resonator has the feature that it can be made smaller and lighter. When using this oscillator as a voltage controlled oscillator, the load Q (Qex)
It is desirable to reduce the amount of noise and increase the degree of modulation.

FIG. 1a is a diagram showing the structure of a conventional voltage controlled oscillator using a dielectric resonator. In the figure, 1 is a cylindrical high dielectric material, and the shaded part in the figure is a high dielectric constant dielectric material with ε _r (relative dielectric constant)=39, and the inside and outside are metalized. 2 is hollow;
It operates as a λg/2 length TEM mode resonant element with both ends open. 3 is a transistor oscillation element whose base is coupled to the resonant element 2 through a coupling element 4. 5 is an output coupling element, and 6 is a coupling element that couples the voltage control varactor 7 to the resonator. This oscillator oscillates at the resonant frequency of the resonator 1 with base and emitter voltages V _b and V _e applied to the base and emitter of the transistor, respectively. A varactor 7 is coupled to the other end of the oscillator, and operates as a voltage controlled oscillator that modulates the oscillation frequency by applying a modulating voltage V to the varactor and changing the varactor capacitance.

FIG. 1b shows the cross-sectional view and the electromagnetic field distribution. In the figure, the solid line shows the electric field distribution, and the broken line shows the magnetic field distribution. In order to operate an oscillator with this type of structure as a voltage controlled oscillator, it is necessary to strengthen the coupling between the oscillator and the external circuit, reduce the load, and
That is, by lowering the external Q (Q _ex ), a change in the resonant frequency due to a change in the capacitance of the varactor coupled to the resonator is increased, thereby increasing the degree of modulation. However, in the conventional technology, the coupling element 5 shown in FIG. Since the external leakage electromagnetic field is small, there is a limit to the coupling between the resonator and the external circuit, and Q _ex cannot be lowered, making it impossible to increase the degree of modulation. That is, although a dielectric resonator with a high dielectric constant and low dielectric loss can be used to make the circuit smaller and have higher performance, it has the disadvantage that it is unsuitable for use as a voltage controlled oscillator. Such drawbacks of the prior art are due to the fact that the dielectric resonator is configured only as a resonant element and the coupling element is provided outside the dielectric resonator.

An object of the present invention is to provide a voltage-controlled oscillator constructed by using a cylindrical dielectric as a resonant element, coupling an oscillation element to one end of the resonant element, and coupling a voltage-controlled varactor to the other end. The object of the present invention is to provide a voltage controlled oscillator using a dielectric resonator that can increase the degree of modulation by strengthening the coupling between coupling elements and lowering Q _ex .

In order to achieve the above object, the voltage controlled oscillator according to the present invention has a hollow λg/2 length whose inner surface is metallized within a cylindrical dielectric body whose outer surface is metallized.
In a voltage controlled oscillator configured by providing a TEM mode resonant element, one end of the resonant element coupled to an oscillation element, and the other end coupled to a voltage controlled varactor, an inner surface coupled to the resonant element within the dielectric body; providing a second hollow coupling element metallized with
One end of this coupling element is connected to an external circuit.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 2 is a diagram showing the structure of a dielectric resonator voltage controlled oscillator according to the present invention. In the figure, 1 has a built-in resonator and coupling circuit, relative dielectric constant ε _r = 39
It is a high permittivity dielectric material. It has a cylindrical shape, and its circumferential surface is metallized. Further, 2 is hollow, and the inner surface of the hollow is metalized to operate as a λg/2 length TEM mode resonator with both ends open. 3 is a transistor oscillation element whose base is coupled to the resonator 1 by a coupling element 4. 6 is a coupling element that couples the voltage control varactor 7 to the resonator. The operation as an oscillator is the same as that in FIG. 1, and it operates as a voltage controlled oscillator whose oscillation frequency is changed by the voltage V applied to the varactor 7. Here, 8 is a λg/2 long hollow coupling element which is coupled to the resonant element 2 within the dielectric 1, and the inner surface of the hollow is metallized. Further, one end of this coupling element is connected to an external output terminal.

FIG. 2b shows the electromagnetic field distribution within the dielectric 1, where the solid line shows the electric field distribution and the broken line shows the magnetic field distribution. In FIG. 2, the resonant element 2 and the coupling element 8 are coupled by a distance d, and the coupling degree Q _ex with the external circuit is d
It can be adjusted by That is, if the interval d is large, the coupling will be sparse, and if Q _ex is high and d is small, the coupling will be dense and Q _ex will be low. With such a structure, Q _ex can be lowered by tightly coupling the resonant element 2 with the external circuit, and the degree of modulation can be increased as described above.

As is clear from the above description, the present invention can increase the modulation degree of a voltage controlled oscillator using a small and lightweight high-permittivity dielectric oscillator, and furthermore, the modulation degree can be adjusted. When used in synchronous oscillators and the like, these circuits can be made smaller and lighter.

[Brief explanation of the drawing]

Figure 1a is a diagram showing the structure of a voltage controlled oscillator using a conventional dielectric resonator, Figure 1b is a cross-sectional view of a dielectric to show the electromagnetic field distribution, and Figure 2a is a dielectric according to the present invention. FIG. 2b is a diagram showing an embodiment of a voltage controlled oscillator using a resonator, and is a cross-sectional view of a dielectric material to show the electromagnetic field distribution. 1... Cylindrical high permittivity dielectric, 2... TEM mode λg/2 length resonant element, 3... Transistor oscillation element, 4... Coupling element coupling the resonant element 2 and the base of the transistor, 5... Dielectric Output coupling element that couples to the external leakage electromagnetic field of the body resonator, 6... Coupling element that couples the modulating varactor 7 and the resonant element 2, 7... Modulating varactor, 8... Resonant element 2 inside the dielectric body. λg/2 long coupling element that couples to.

Claims (1)

[Claims] 1 A hollow λg/2-length TEM mode resonant element whose inner surface is metallized is provided in a cylindrical dielectric whose outer surface is metallized, an oscillation element is coupled to one end of this resonant element, and a voltage control varactor is connected to the other end. In the voltage controlled oscillator configured by coupling, a second hollow coupling element having a metallized inner surface coupled to the resonant element is provided in the dielectric body, and one end of this coupling element is connected to an external circuit. A voltage controlled oscillator using a dielectric resonator.