JPH1174728A - High frequency local oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the high frequency local oscillator in which sealing is attained without addition of a component, the adjustment is made after the assembling and an optional frequency is easily obtained. SOLUTION: The oscillator is provided with a high frequency local oscillation circuit board 2 consisting of a dielectric board on the major side of which a microstrip line is formed on the rear side of which an earth pattern is formed, a metallic case 1 and a board fixing plate 3 that clip the high frequency local oscillation circuit board 2, and a dielectric resonator 4 is sealed in a metallic cavity forming a space surrounded by the metallic case 1 and the board fixing plate 3. The earth pattern of the high frequency local oscillation circuit board 2 exposed in the metallic cavity is removed and a flexible part 8 forming an air gap between the board fixing plate 3 and the high frequency local oscillation circuit board 2 is formed to part of the board fixing part 3 configuring the cavity and the frequency is adjusted by deforming the flexible part 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to radar and radio communication using a high frequency wave such as a microwave band or a millimeter wave band as a carrier wave.
A high-frequency local oscillator built in a transceiver used for satellite broadcasting or the like and having a dielectric resonator mainly used for modulation and demodulation, particularly a high frequency having a structure capable of obtaining an arbitrary oscillation frequency with a simple configuration It relates to a local oscillator.

[0002]

2. Description of the Related Art Hitherto, a dielectric resonator has been generally used in a high-frequency local oscillator used in a frequency band of several GHz or more in order to stabilize the frequency of the oscillator and simplify the circuit configuration. In a high-frequency local oscillator having a dielectric resonator, the frequency characteristic changes depending on the volume of the metal cavity surrounding the dielectric, and particularly, the size of the gap between the dielectric resonator and the inner wall of the metal cavity determines the Q of the oscillator. It is a big factor. Therefore, a screw (tuning screw) is screwed into the inner wall of the metal cavity above the dielectric resonator and moved up and down, or a bellows is provided and physically deformed to change the above-mentioned gap. ing.

FIGS. 3 and 4 are cross-sectional views of such a conventional high-frequency local oscillator. FIG. 3 shows a case where the frequency is adjusted by the former screw, and FIG. 4 shows a case where the latter bellows is employed. In these figures, 1 is a metal housing formed of aluminum die casting or the like, 2 is a high-frequency local oscillator circuit board made of a dielectric substrate having a microstrip line formed on the main surface and a ground pattern formed on the back surface, and 3 is A board fixing plate made of an aluminum alloy plate or the like and closely contacting the ground pattern of the high-frequency local oscillator circuit board 2;
Is a dielectric resonator fixed to the high-frequency circuit board 2, 5 is a tuning screw screwed into a wall surface of the housing 1 above the dielectric resonator 4, 6 is a sealing material that fills a gap between the tuning screw 5 and the housing 1. Reference numerals 7 denote an inner metal housing that covers the dielectric resonator 4.

In FIG. 3, a dielectric resonator 4 is mounted and fixed on a high-frequency local oscillation circuit board 2 sandwiched between a metal housing 1 and a substrate fixing plate 3, and is provided above the dielectric resonator 4. A movable tuning screw 5 is screwed into the inner wall of the housing 1. Therefore, a cavity is formed by the inner wall of the metal housing 1 and the substrate fixing plate 3, and the tuning screw 5 is turned up and down by rotating the tuning screw 5 to obtain an arbitrary frequency. Further, since there is a slight gap between the metal casing 1 and the tuning screw 5, the tuning screw 5 is used to prevent water or the like from entering.
Sealing material 6 is applied so as to cover.

In FIG. 4, the dielectric resonator 4 is mounted and fixed on the high-frequency local oscillation circuit board 2 in the same manner as in FIG. 3, and is covered by a metal inner housing 7. The metal cavity is constituted by the inner housing and the substrate fixing plate 3, and the frequency is adjusted by deforming a bellows 7 a provided on the wall surface above the dielectric resonator 4 of the inner housing 7.

[0006]

However, according to the configuration shown in FIG. 3, when the frequency is adjusted with the movable tuning screw 5 penetrating the metal housing 1, a sealing material 6 is required for sealing. The number of members and man-hours increase, and the product cost increases.

Further, according to the configuration of FIG. 4, since the entire high-frequency local oscillator is covered by the metal casing, the frequency adjustment is performed during the assembly. Therefore, the frequency may fluctuate due to a pressure difference between the inside and outside of the housing after assembly, but it cannot be corrected unless disassembled. That is, the fact that the frequency adjustment is in the middle of the assembly causes a decrease in the yield, and in the case of the recovery, the number of disassembly steps also increases the product cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to perform sealing without adding a member for sealing, adjust after assembly, and adjust an arbitrary frequency. To provide a high-frequency local oscillator that can easily obtain the local oscillator.

[0009]

According to the present invention, there is provided a high-frequency local oscillation circuit board comprising a dielectric substrate having a microstrip line formed on a main surface and an earth pattern formed on a back surface. A metal cavity and a substrate fixing plate sandwiching the high-frequency local oscillation circuit board, and a metal cavity constituted by a space surrounded by the metal housing and the substrate fixing plate, which were sealed in the metal cavity. A high frequency local oscillator comprising a dielectric resonator, wherein a ground pattern of the high frequency local oscillation circuit board exposed in the metal cavity is removed, and the substrate is fixed to a part of the substrate fixing plate forming the cavity. A flexible portion forming a gap is formed between the fixed plate and the high-frequency local oscillation circuit board, and the frequency is adjusted by deforming the flexible portion.

The dielectric resonator may be fixed to the main surface of the high-frequency local oscillation circuit board in the metal cavity, even if the dielectric resonator faces the main surface of the high-frequency local oscillation circuit board in the metal cavity. To be fixed to the inner wall of the metal housing.

Preferably, the flexible portion is a bellows-like stepped convex portion formed by drawing a part of the substrate fixing plate.

According to the above configuration, since the sealing can be performed without using the sealing material shown in FIG. 3, members and man-hours can be reduced. In addition, since the frequency can be adjusted after assembly, an arbitrary oscillation frequency can be obtained relatively easily.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. However, the same or corresponding components are denoted by the same reference symbols throughout the drawings, and redundant description is avoided.

FIG. 1 is a view showing a first embodiment of a high-frequency local oscillator according to the present invention, which is shown in a sectional view for understanding the structure. In this figure, a bellows-shaped flexible portion which is expandable and contractible below the dielectric resonator of a substrate fixing plate 3 for fixing a high-frequency local oscillation circuit substrate 2 having a dielectric resonator 4 mounted on a metal housing 1. By arranging 8 and modifying it, an arbitrary frequency can be obtained.

In the present embodiment, the metal cavity surrounding the dielectric resonator 4 is constituted by a space surrounded by the inner wall of the metal housing 1 and the substrate fixing plate 3. The portion of the high-frequency local oscillation circuit board 2 exposed in the metal cavity has a ground pattern removed, and the ground pattern at that portion is replaced by the board fixing plate 3. Therefore, the spatial electric field penetrating the dielectric resonator 4 in the vertical direction extends to the substrate fixing plate 3 without being blocked by the high-frequency local oscillation circuit substrate 2.

A flexible portion 8 composed of a bellows-like stepped convex portion obtained by performing a drawing process by a sheet metal press or the like is formed in a portion constituting the metal cavity of the substrate fixing plate 3. A gap is generated between the circuit board 2 and the board fixing plate 3. Further, since the surface area is locally increased by drawing, only the plate pressure in this portion is thinner than in other portions. Therefore, when an external force is applied here, the stress concentrates, so that only the flexible portion 8 can be deformed without affecting other parts. Further, by giving a deformation exceeding the elastic limit, a permanent strain is left and permanent deformation is left. The gap with the body resonator can be fixed.

Although not shown, an active oscillation element such as an FET coupled to the dielectric resonator 4 is mounted on the main surface of the high-frequency local oscillation circuit board 2 on which a microstrip line is formed. Therefore, the gap between the dielectric resonator 4 and the inner wall of the metal cavity can be changed by the deformation of the flexible portion 8, whereby the frequency can be adjusted.

This embodiment has the above-described configuration.
The sealing can be maintained without applying a sealing material, and an arbitrary frequency can be easily obtained by adjusting the frequency after assembly. Note that the dielectric resonator 4 may be fixed to the metal housing 1 as shown in FIG. Also in this case, the gap between the cavity wall surface and the dielectric resonator 4 changes due to expansion and contraction of the flexible portion 8, so that the frequency can be adjusted. In addition, since the dielectric resonator 4 is fixed to the metal housing, the bonding step of the dielectric resonator can be performed in parallel with the element mounting step on the high-frequency local oscillation circuit board 2. Can be shortened.

Although the embodiments of the present invention have been described in detail, the present invention is not limited thereto, and various modifications are possible. For example, in the above embodiment, the flexible portion is a bellows-like stepped convex portion. However, since it is only necessary to change the gap between the cavity inner wall and the dielectric resonator, for example, a hemispherical or trapezoidal convex portion It may be a unit. However, it is preferable to use a bellows-like stepped projection because regularity is easily obtained in deformation and frequency adjustment is easy.

[0020]

As described above, according to the present invention,
An arbitrary oscillating frequency can be easily obtained by providing a flexible part on the board fixing plate and deforming it, so that the sealing is maintained without using the sealing material that was required conventionally, and after assembly. Since the frequency can be adjusted, it is possible to contribute to a reduction in the number of components, an improvement in yield, and a reduction in product cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional high-frequency local oscillator.

FIG. 4 is a cross-sectional view showing another conventional high-frequency local oscillator.

[Explanation of symbols]

 1: Metal casing 2: High frequency local oscillation circuit board 3: Board fixing plate 4: Dielectric resonator 5: Tuning screw 6: Sealing material 7: Inner casing 7a: Bellows 8: Available part

Claims (3)

[Claims] 1. A high-frequency local oscillation circuit substrate comprising a dielectric substrate having a microstrip line formed on a main surface thereof and an earth pattern formed on a back surface, a metal housing for holding the high-frequency local oscillation circuit substrate, and substrate fixing. A high-frequency local oscillator comprising a plate, a metal cavity defined by a space surrounded by the metal housing and the substrate fixing plate, and a dielectric resonator sealed in the metal cavity; The earth pattern of the high frequency local oscillation circuit board exposed in the tee is removed, and a gap is formed between the substrate fixing plate and the high frequency local oscillation circuit board in a part of the substrate fixing plate forming the cavity. A high-frequency local oscillator characterized in that a flexible part is formed and the frequency is adjusted by deforming the flexible part. 2. The high-frequency local oscillator according to claim 1, wherein the dielectric resonator is fixed to an inner wall of the metal housing facing a main surface of the high-frequency local oscillation circuit board in the metal cavity. 3. The high-frequency local oscillator according to claim 1, wherein the flexible portion comprises a bellows-like stepped convex portion formed by drawing a part of the substrate fixing plate.