JP2001274624A - Microwave oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an oscillation output characteristic of a microwave oscillator employing a magnetostatic wave resonator. SOLUTION: A nonmagnetic metallic ring is placed around a magnetic pole in the microwave oscillator of a structure having a magnetic circuit consisting of a modulation coil and the magnetic pole to apply a DC magnetic field to a magnetostatic wave element placed on a microwave circuit board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oscillator using a ferrimagnetic thin film such as YIG (yttrium / iron / garnet).

[0002]

2. Description of the Related Art An external DC magnetic field is applied to a ferrimagnetic thin-film magnetostatic wave resonator formed by processing a YIG single-crystal magnetic thin film formed on a nonmagnetic substrate such as GGG (gadolinium / gallium / garnet) into a required shape by liquid phase epitaxial growth. Is applied, a magnetostatic wave is excited, and a microwave active element (for example, Ga
A microwave oscillator that obtains a microwave output by being combined with an As FET or the like has been proposed. FIG. 2 shows a structural sectional view of a microwave oscillator according to the prior art. A structure in which a microwave circuit board 2 on which a magnetostatic wave resonator 1 is disposed is fixed in a yoke 3 made of permalloy or the like, and a magnetic field 4 and a modulation coil 5 apply a DC magnetic field to the magnetostatic wave resonator to obtain a microwave output. Has become. Generally, the yoke 3, the magnetic pole 4, and the modulation coil 5 are collectively called a magnetic circuit. The frequency of the microwave output is controlled by changing the magnitude of the DC magnetic field by the current flowing through the modulation coil 5.

[0003]

However, in the microwave oscillator having the above-described structure, cavity resonance occurs in the yoke 3 due to the hollow portion 6 on the microwave circuit board, and as a result, oscillator characteristics are deteriorated such as oscillation stop. There is a problem that FIG. 4 shows the frequency characteristics of the oscillation output of a microwave oscillator according to the prior art. About 8.9 ~
At 9.1 GHz, a phenomenon of oscillation stop was observed. As a means for solving this problem, changing the shape and dimensions of the magnetic pole 4 and the yoke 3 to change the volume of the cavity and the coupling with the circuit board to change the cavity resonance frequency to outside the operating frequency band of the oscillator. Although a method is conceivable, the magnetic characteristics of the magnetic circuit, such as the intensity and distribution of the DC magnetic field, change, and the design becomes complicated and difficult.

[0004]

In order to control the cavity resonance, a metal ring is arranged around the magnetic pole without changing the shape of the magnetic pole and the yoke to change the volume of the cavity and the coupling with the circuit board. As a result, they found a method of changing the cavity resonance frequency outside the operating frequency band of the oscillator to prevent deterioration of the oscillation characteristics. The optimum shape and size of the metal ring are determined based on the operating frequency band of the oscillator and the cavity resonance frequency. Further, since the magnetic characteristics must not be deteriorated by the metal ring arranged in this way, a second object of the present invention is to perform cavity resonance control without deterioration of the magnetic characteristics. Therefore, if a non-magnetic metal is used as the metal ring, it is possible to control the cavity resonance without deteriorating the magnetic field distribution and the magnetic field strength. As the material of the nonmagnetic metal, for example, Al, BS, Cu can be used.

[0005]

FIG. 1 is a diagram showing an embodiment of the present invention. In addition to the conventional oscillator structure, the nonmagnetic metal ring 7 is
, And the operating frequency band is about 8.1-9.
A 9 GHz band oscillator of 7 GHz was manufactured. The shape and dimensions of this metal ring are optimized from the operating frequency band of the oscillator and the cavity resonance frequency, and the ring diameter is the same as the inner dimension of the yoke.
The height was 24 mm and the height was 6 mm. Al was used as the material of the metal ring. FIG. 3 shows the frequency characteristics of the oscillation output of this oscillator. Over the operating frequency band of 8.1 to 9.7 GHz, no oscillation stop phenomenon due to cavity resonance in the conventional structure was observed, and a good oscillation output was obtained.

[0006]

According to the present invention, the cavity resonance frequency can be controlled by disposing the non-magnetic metal ring around the magnetic pole, so that a stable oscillation output can be obtained without stopping the oscillation. In addition, the use of a non-magnetic metal facilitated stabilization of oscillation characteristics without deteriorating magnetic characteristics.

[Brief description of the drawings]

FIG. 1 is a structural sectional view showing an embodiment according to the present invention.

FIG. 2 is a structural sectional view of a microwave oscillator according to the related art.

FIG. 3 is a frequency characteristic diagram of an oscillation output of the microwave oscillator according to the embodiment.

FIG. 4 is a frequency characteristic diagram of an oscillation output of a microwave oscillator according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetostatic wave resonator 2 Microwave circuit board 3 Yoke 4 Magnetic pole 5 Modulation coil 6 Hollow part 7 Nonmagnetic metal ring

Claims (2)

[Claims] 1. A microwave oscillator having a magnetic pole for applying a DC magnetic field to a magnetostatic wave element disposed on a microwave circuit board and a magnetic circuit comprising a modulation coil, wherein a nonmagnetic metal is provided around the magnetic pole. A microwave oscillator characterized by placing a ring. 2. The microwave oscillator according to claim 1, wherein the material of the nonmagnetic metal ring is Al, BS, or Cu.