JP2003110317A - Planar circuit equipped with cavity resonator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To join a cavity resonator, suitable for a planar circuit to the planar circuit of high frequency waves such as microwaves or milliwaves, so as to provide a high-performance planar circuit having small power loss. SOLUTION: A circuit pattern 5 is formed on the one side of a dielectric board 3, and a grounding conductor 4 is provided on the other side of the dielectric board 3. A cavity resonator 8, composed of a metal rod 6 and a conductive cover 7 covering the metal rod 6, is provided on the one side of the dielectric board 3, so as to be electromagnetically coupled with the circuit pattern 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave or millimeter wave planar circuit for forming a circuit on the surface of a dielectric substrate by a microstrip line or the like. More specifically, the present invention relates to a planar circuit using a cavity resonator as a resonator used for an oscillator or a filter of the planar circuit.

[0002]

2. Description of the Related Art As a microwave or millimeter wave circuit, a three-dimensional circuit using a waveguide or a cavity resonator is used, and a transmission line, its inductance, or a line is formed by a strip line on the surface of a dielectric substrate. A planar circuit is known in which a filter or the like is formed by a capacitor or the like in between.
In a three-dimensional circuit, as a matter of course, a cavity resonator is used to form a resonance circuit or the like, and for example, a semi-coaxial cavity resonator is used as a wavelength meter or a klystron resonator. However, in the planar circuit, the resonant circuit is formed by utilizing the inductance of the strip line or the like and the capacitance between the lines. Further, for example, when a more precise resonance circuit is required to stabilize the oscillation frequency of a transistor oscillator or to form a filter, a dielectric resonator or a coaxial resonance type block made of ceramics or the like is used as a dielectric. It may be mounted on a substrate and assembled.

[0003]

As described above, in the conventional high-frequency plane circuit, when a resonator is required, a resonator using a dielectric is used, but in the dielectric resonator, the dielectric is always used. However, there is a problem that even if the dielectric material has a small loss, the loss becomes large and the Q value of resonance becomes low as compared with a resonator using a cavity. In addition, in the case of millimeter waves, the size of the resonator is reduced, which makes it difficult to process the dielectric.

The present invention solves such a problem, and a cavity resonator suitable for a plane circuit is coupled to a plane circuit for high frequency waves such as microwaves and millimeter waves, and the plane loss is small and the performance is high. The purpose is to provide a circuit.

Another object of the present invention is to provide a specific structure of a cavity resonator part suitable for coupling the cavity resonator to a planar circuit.

[0006]

A planar circuit having a cavity resonator according to the present invention comprises a dielectric substrate, a circuit pattern formed on one side of the dielectric substrate, and another side of the dielectric substrate. A grounding conductor provided on the one side, and a cavity resonator formed of a metal rod provided on the one surface side of the dielectric substrate so as to be electromagnetically coupled to the circuit pattern and a conductive cover covering the periphery of the metal rod. It has.

With this structure, a semi-coaxial cavity resonator having a structure in which the circumference of a metal rod is covered with a conductive cover is coupled to a planar circuit, so that it can be easily applied to a circuit on a dielectric substrate. Can be combined with. Moreover, since the space between the metal rod and the conductive cover is a resonator, there is almost no loss.

For example, the cavity resonator constitutes a filter, or an oscillator is connected to the circuit pattern, and the cavity resonator is used for fixing the oscillation frequency.

The metal rod may be bent along the surface of the dielectric substrate, or the metal rod may include a plurality of metal rods, and the plurality of metal rods may be covered by one conductive cover. Good. Since the metal rod is bent, it does not protrude on the dielectric substrate, and the band can be widened by using a plurality of metal rods.

The dielectric substrate is housed in a housing, a lid is provided on the front surface side of the dielectric substrate, the metal rod and the conductive cover penetrate the lid, or the lid and the inside of the housing. Since the housing and the lid are made of a conductive material, the cavity resonator can be simply housed while completely blocking noise. The lid may be made of a conductive material, and the thickness thereof may be adjusted so that the lid also serves as the conductive cover.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a planar circuit having a cavity resonator according to the present invention will be described with reference to the drawings. In the planar circuit according to the present invention, a circuit pattern 5 is formed on one surface side of the dielectric substrate 3 as shown in FIG.
Is formed, and the ground conductor 4 is provided on the other surface side of the dielectric substrate 3. Then, a metal rod 6 is formed on the one surface side of the dielectric substrate 3 so as to be electromagnetically coupled to the circuit pattern 5.
And a cavity resonator 8 made of a conductive cover 7 provided so as to cover the periphery of the metal rod 6.

As the dielectric substrate 3, an electrically insulating substrate made of, for example, ceramics or glass epoxy is used, and a copper film coated on the entire surface (one surface) thereof is etched into a predetermined pattern or a predetermined pattern is formed. The circuit pattern 5 is printed on the surface of the dielectric substrate by printing a pattern.
Are formed. The circuit pattern 5 constitutes a transmission line such as a microwave, and an inductance or a capacitance is formed according to its width and length, and a desired circuit is formed by utilizing these.

The cavity resonator 8 is, in the example shown in FIG.
In the example of configuring the band elimination filter, the metal rod 6 is provided with a through hole in the dielectric substrate 3 and is fixed to the hole so as to be connected to the ground conductor 4. At this time, by providing a conductive film on the side surface in the through hole to form a so-called through hole, the electrical contact between the metal rod 6 and the ground conductor 4 can be improved, which is preferable. The length H of the metal rod 6 is determined by the operating frequency of the band elimination filter, and is formed to have a length of about ¼ wavelength of the frequency. Then, by providing a conductive cover 7 around the metal rod 6 so as to form a coaxial structure with the metal rod 6,
A semi-coaxial cavity is formed between the conductive cover 7 and the conductive cover 7 to form a semi-coaxial cavity resonator. The size of the coupling between the semi-coaxial cavity resonator and the circuit pattern 5 depends on the circuit pattern 5.
Is determined by the distance L between the metal rod 6 and the metal rod 6, and if L is small, the bond is large, and if L is large, the bond is small. The larger the coupling, the wider the stopband, and the smaller the coupling, the narrower the stopband.

The resonance frequency of the cavity resonator of this structure is finely adjusted by adjusting the distance G between the tip of the metal rod 6 and the top of the conductive cover 7. That is, when the resonance frequency adjusting section (top of the conductive cover 7) 7a is pressed to reduce the gap G, the resonance frequency becomes low, and when the resonance frequency adjusting section 7a is pulled to increase the gap G, the resonance frequency becomes high.

In the example shown in FIG. 1, the circuit board 5 is provided, the dielectric substrate 3 to which the cavity resonator 8 is attached is housed in the housing 1, and the lid 2 is provided on the front surface side.
Is provided so as to penetrate the metal rod 6 and the conductive cover 7, and is fixed and closed to the housing 1 by a screw 18. The above-mentioned conductive cover 7 is fixed to the lid body 2.
The casing 1 and the lid 2 are made of a conductive material such as Fe plated with Al and Ni, respectively, to completely shield the circuit including the microstrip line formed on the dielectric substrate from the outside. Therefore, it is very convenient because it is not affected by noise and the like, but it is not necessarily limited to using a conductive member, and a non-conductive member such as a plastic resin can also be used. .

According to the present invention, since the resonator is constructed by only raising the metal rod on the dielectric substrate on which the circuit pattern is formed and covering the periphery thereof with the conductive cover, the cavity resonance is achieved even in the planar circuit. The device can be installed very easily. Moreover, the length of the metal rod is about 1/4 as described above.
The wavelength is about the same, and from microwave to millimeter wave, it is several cm or less, and the protrusion is not so problematic. As a result, even when a band stop filter is formed in a planar circuit, a semi-coaxial cavity resonator is used, so that it is affected by the dielectric loss that is always present in the dielectric, as in a conventional dielectric resonator. Since there is no resistance loss of the conductor, the loss can be almost ignored, and a very low loss filter can be constructed.

FIG. 2 is an explanatory view of a partially cutaway plane and a cross section similar to FIG. 1 showing another embodiment of the present invention. That is, in this example, the metal rod 6 is connected to the dielectric substrate 3
It is bent so that it can be housed in the housing 1 and the lid 2. Even in this case, the function as the coaxial resonator does not change, and the cavity resonator does not penetrate through the lid body 2 and protrudes to the upper portion, which is preferable. The other parts are the same as in the example shown in FIG. 1, and the same parts are designated by the same reference numerals and the description thereof is omitted.

FIG. 3 is also a partially cutaway plan view and sectional view similar to FIG. 1, showing another embodiment of the present invention. Also in this example, the band elimination filter is configured similarly to the examples shown in FIGS. 1 and 2. In this example, one end of the metal rod 6 is not provided in the through hole provided in the dielectric substrate 1 so as to be connected to the ground conductor 4, but is directly connected to the circuit pattern 5 by soldering or the like. Different in points. Thus, even if the metal rod 6 is directly connected to the circuit pattern 5, the circuit pattern and the cavity resonator can be coupled. Also in FIG. 3, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 4 is a partially cutaway plan view and sectional view similar to FIG. 1, showing still another embodiment of the present invention. This example is an example of forming a bandpass filter, and the metal rod 6 is fixed in the through hole of the dielectric substrate 1 by connecting one end thereof to the ground conductor 4 so as to be coupled to the two strip lines 5a and 5b. It was done. The conductive cover 7 forming the cavity resonator 8 and other structures are all shown in FIG.
The same parts as in the example shown in FIG.

5 (a) and 5 (b) are cross-sectional views (A-A cross section of (b)) showing still another embodiment of the present invention.
FIG. 3 is an explanatory view of a vertical section. That is, in the example shown in FIG. 5, three metal bars 6a, 6b, 6c are arranged side by side between the circuit patterns 5a and 5b, and the three metal bars 6
By covering with one conductive cover 7, a wide band and a sharp isolation in the stop band can be achieved. Further, in this example, the resonance frequency adjusting section 7a, which is the top of the conductive cover 7, is provided with resonance frequency adjusting screws 9a to 9c so as to correspond to the metal rods 6a to 6c, and the thrust length thereof is adjusted. By doing so, the resonance frequency can be finely adjusted. This structure can be similarly adopted in each of the above-described examples. In the example shown in FIG. 5, the number of metal rods is three, but the number of metal rods may be two, and if the number is four or more, a wider band can be achieved.

FIG. 6 is an explanatory view of a partially cutaway plane and a cross section similar to FIG. 1 showing still another embodiment of the present invention. That is, the example shown in FIG. 6 is an example in which the cavity resonator is used for stabilizing the oscillation frequency of the Gunn oscillator.
The Gunn oscillator oscillates at a frequency at which the Gunn diode has a negative resistance and the reactance component including the Gunn diode becomes zero. As shown in FIG. 6, near the Gunn diode 10 connected to the circuit pattern 5, the metal rod 6 and the conductive cover are connected to the circuit pattern 5 (in the example shown in FIG. The cavity resonator 8 (also used as a property cover) is provided, so that the reactance seen from the Gunn diode 10 toward the metal rod 6 changes rapidly near the resonance frequency, and the reactance component is zero. Exists and oscillates at that frequency.

A resonator is provided near the Gunn diode,
The method of oscillating at the resonance frequency of the resonator is similar to the conventional planar circuit, but in the present invention, a cavity resonator is used for this resonator instead of the conventional dielectric resonator. There are features. By using the cavity resonator, the Q value of the resonator can be increased and a low noise oscillator can be configured. In addition, in FIG. 6, the same parts as those in FIG.
Reference numerals a and 11b denote electrode pads of the Gunn diode 10, and electrode terminals for connection with an external power source are not shown. Further, in the example shown in FIG. 6, the lid 2 that closes the upper surface side of the housing is thickened with a conductive material so that the lid 2 also functions as a conductive cover that forms the cavity resonator 8. The cavity 2a is formed so as to be concentric with the metal rod 6. The configuration in which the lid 2 and the conductive cover of the cavity resonator 8 are used in common is not limited to this example, and can be applied to the above-described examples.

FIG. 7 is a view showing still another embodiment of the present invention, and is a perspective explanatory view showing only a main part. That is,
The example shown in FIG. 7 is an example in which the cavity resonator 8 is applied to an oscillator using the FET 12, and the source terminal of the FET 12 is
A bias circuit including a chip resistor 16 is connected, an output terminal 15 is provided via a DC cutting chip capacitor 13, and a load chip resistor 14 is connected to a gate terminal of the FET 12 via a circuit pattern 5. , A metal rod 6 forming a cavity resonator is provided so as to be coupled to the circuit pattern 5. Further, the power supply terminal 17 is connected to the drain terminal of the FET 12. The metal rod 6 forming the cavity resonator is fixed in the through hole provided in the dielectric substrate 1 as in the example shown in FIG.
It is connected to a ground conductor (not shown) and has a coaxial structure with a conductive cover (not shown) to form a band elimination filter.

As for the oscillation condition of the FET oscillator, the FET has a negative resistance and the reactance component oscillates at a frequency of 0 as in the case of the Gunn oscillator shown in FIG. FET1
When looking at the metal rod 6 side from 2, there is reflection in the vicinity of the resonance frequency, the frequency component deviating from that frequency is absorbed by the load chip resistor 14, and the reactance component rapidly changes in the vicinity of the resonance frequency. Oscillation is obtained at. Also,
Components other than near the resonance frequency are absorbed by the load chip resistor 14, and a desired frequency, that is, a frequency component other than the resonance frequency cancels the negative resistance and does not oscillate. This operation by the FET is similar to the oscillator by the conventional FET, but in the present invention, the cavity resonator is used in spite of the planar circuit instead of the dielectric resonator. Similarly, the Q value can be increased and a low noise oscillator can be configured. Note that, in FIG. 7, the housing, the lid, the conductive cover and the like are omitted and not shown.

[0025]

As described above, according to the present invention, even though it is a planar circuit using a dielectric substrate, a metal rod is erected on the dielectric substrate and a coaxial structure is formed around it. Since the semi-coaxial cavity resonator is formed by providing the conductive cover, the cavity circuit having a large Q value can be provided in the planar circuit. As a result, when applied to a filter, a sharp attenuation characteristic can be realized with a relatively low loss, and when applied to an oscillator, an oscillator having a good noise characteristic can be obtained. In particular, when used in a high frequency band such as a millimeter wave, fine processing of the dielectric is not required, which has an advantage of improved workability.

[Brief description of drawings]

FIG. 1 is an explanatory view of a plane and a cross section in which a part of a main part is cut out, showing an embodiment of a plane circuit according to the present invention.

FIG. 2 is an explanatory view similar to FIG. 1, showing another embodiment of the planar circuit according to the present invention.

FIG. 3 is an explanatory view similar to FIG. 1, showing another embodiment of the planar circuit according to the present invention.

FIG. 4 is an explanatory view similar to FIG. 1, showing another embodiment of the planar circuit according to the present invention.

FIG. 5 is an explanatory view of a horizontal cross section and a vertical cross section showing another embodiment of the planar circuit according to the present invention.

FIG. 6 is an explanatory view similar to FIG. 1, showing another embodiment of the planar circuit according to the present invention.

FIG. 7 is a perspective explanatory view of a main portion showing another embodiment of the planar circuit according to the present invention.

[Explanation of symbols]

3 Dielectric substrate 4 Ground conductor 5 circuit patterns 6 metal rod 7 Conductive cover 8 cavity resonator

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5J006 HA02 HA15 HA17 HA18 HA28                       HA33 HC01 HC24 JA02 LA02                       LA25 MA01 MB01 MB03 NA08                       NB07 NC03 NF01 PA01 PA03                       PA04

Claims (7)

[Claims] 1. A dielectric substrate, a circuit pattern formed on one side of the dielectric substrate, a ground conductor provided on the other side of the dielectric substrate, and an electromagnetic coupling with the circuit pattern. A planar circuit having a cavity resonator comprising: a metal rod provided on the one surface side of the dielectric substrate; and a cavity resonator formed of a conductive cover surrounding the metal rod. 2. A planar circuit having a cavity resonator according to claim 1, wherein the cavity resonator constitutes a filter. 3. An oscillator is connected to the circuit pattern,
The planar circuit having a cavity resonator according to claim 1, wherein the cavity resonator is used for fixing an oscillation frequency. 4. The planar circuit having a cavity resonator according to claim 1, wherein the metal rod is bent along the surface of the dielectric substrate. 5. The cavity resonator according to claim 1, 2, 3 or 4, wherein the metal rod is composed of a plurality of metal rods, and the plurality of metal rods are covered with one conductive cover. Planar circuit. 6. The dielectric substrate is housed in a housing, a lid is provided on the surface side of the dielectric substrate, the metal rod and the conductive cover penetrate the lid, or the lid and the The housing is provided so as to be housed in a housing.
A planar circuit having a cavity resonator according to claim 2, 3, 4 or 5. 7. The planar circuit having a cavity resonator according to claim 6, wherein the lid body is made of a conductive material and has a structure which also serves as the conductive cover.