JPH0481884B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a resonator suitable for filters, oscillation elements, etc. used in frequency ranges including and exceeding the UHF band.

2. Description of the Related Art Resonators used for filters, oscillation elements, etc. in the above frequency range have conventionally been dielectric coaxial resonators and ceramic resonators. A dielectric resonator has an equivalent circuit in which one capacitor and one coil are connected in parallel as shown in Figure 5A, while a ceramic resonator has an equivalent circuit in which one coil and one coil are connected in parallel as shown in Figure 5B. It has an equivalent circuit consisting of a series circuit of two capacitors and another capacitor connected in parallel.

Problems to be Solved by the Invention Since each resonator has only one coil in the equivalent circuit, it is not possible to magnetically couple multiple resonators using that coil. When configuring a filter by connecting resonators in multiple stages, there is a problem that separate parts such as a capacitor are required as a coupling means, resulting in a bulky structure. SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide resonators that can be easily magnetically coupled to each other without using a separate coupling means.

Means for Solving the Problems To achieve the above object, the resonator of the present invention comprises a coil and a capacitor. The gist of the present invention is to have an equivalent circuit in which two capacitors are connected, and an embodiment in which the above object is achieved by means of this unique equivalent circuit will be described below.

Embodiment FIG. 1 is an equivalent circuit diagram of a resonator of the present invention,
This shows an LC series circuit in which coils L1 and L2 are connected in series on both sides of a first capacitor C1, and an equivalent circuit in which a second capacitor C2 is connected in parallel.

FIG. 2 shows an embodiment of a resonator constructed from this equivalent circuit. FIG. 2A is a front view of a resonator according to an embodiment of the present invention, FIG. 2B is a side view of the resonator of FIG. 2A, and FIG. 2C is a rear view of the resonator of FIG. In the figure, 1 is a dielectric substrate made of FRDR material, etc., and two capacitor electrode patterns 2a, 2b, 3a, 3b are provided on the front side 1a and the back side 1b, respectively.
and coil patterns 4a, 5a are formed by screen printing silver paste, for example. The capacitor has electrode patterns 2a and 3a.
2b and 3b face each other on both sides of the dielectric substrate 1, forming capacitors C1 and C2 having a capacitance determined by the dielectric constant and thickness of the substrate and the opposing areas of the capacitor electrodes. On the other hand, the coil patterns 4a and 5a are formed in such a manner that two capacitors are connected to the electrode patterns 2a and 2b, and 3a and 3b on each of the front and back surfaces of the dielectric substrate 1, respectively. Each coil pattern 4a, 5a forms a coil in terms of high frequency, so its inductance is L.
1, L2, the resonator is the first one described above.
It is represented by an equivalent circuit as shown in the figure.

Especially in the resonator, the two coil patterns 4
It is preferable that a and 5a have an appropriate length so that they can be magnetically coupled with other resonators, and that they are formed as close to the edge of the substrate as possible. Furthermore, within the same resonator, it is desirable to space the two coil patterns 4a and 5a as far apart as possible so that they do not magnetically couple with each other or have electrostatic capacitance. The illustrated example is implemented in the most distant state.

To make this resonator resonate at fr=504MHz,
For example, if C1 is set as C1=18pF, L1,
L2 is from the following formula, If L1=L2, then L1=L2=2.88nH. C2 can be selected depending on the impedance used, regardless of the resonance frequency. In this example, when the impedance is 50Ω, C=
I chose 53pF because the Q was maximum at 53pF.
Here, the dielectric constant ε of the dielectric substrate 1 is 80, and the thickness is
0.4mm, l1=7mm, l2=1.5mm, l3=7mm, l4=3.5
Obtained by setting the value to mm. Also, L
The inductance of 1, L2 is obtained by setting l5 = l6 = 6 mm. Coil pattern 4
The widths W1 and W2 of a and 5a are not related to the inductance value, but the larger the width, the smaller the resistance and therefore the higher the Q, which is preferable. In this example, W
Assuming 1=W2=1.5mm, other dimensions (l1, l2...
FIG. 3 shows the resonance characteristics when the ε and thickness of the dielectric substrate 1 are set as described above. In this case, a very high Q value of 148 was obtained. The reason why such a high Q was obtained is speculation, but it is because the above-mentioned resonator has a unique circuit configuration in terms of an equivalent circuit that is not found in conventional examples, and the width of the coil patterns 4a and 5a is This is thought to be due to the fact that it was made wider to lower the resistance, and that FRDR material was used as the dielectric substrate 1.

In the resonator, the capacitor electrode patterns 2a, 2b, 3a, 3b and the coil patterns 4a, 5a are formed in the same pattern on both the front and back surfaces of the dielectric substrate 1. By aligning the patterns on the front and back surfaces in this way, printing masks with the same pattern can be used during manufacturing, resulting in very high productivity.

Further, in the above embodiment, the dielectric substrate 1 is
A 0.4 mm thick one is used, but by changing the thickness, the capacitance of capacitors C1 and C2 changes and the resonance frequency can be changed, so choose an appropriate thickness in relation to the frequency of use. Good.

FIG. 4 is a front view of an example in which the three resonators described in the above embodiment are magnetically coupled. In this structure, three resonators A, B, and C are arranged in multiple stages, and the coil patterns 4a and 5a of adjacent resonators are brought close to each other and connected by magnetic coupling.

As in this example, by forming the coil patterns 4a and 5a of the resonators A, B, and C near the ends of the dielectric substrate 1, magnetic coupling is possible simply by arranging each resonator next to each other. Furthermore, each resonator also forms an LC circuit with coils connected in series on both sides of a single capacitor.
This constitutes an equivalent circuit according to the present invention.

Effects of the Invention As explained above, according to the present invention, the LC has a coil connected in series on both sides of the first capacitor.
Since it is a resonator with a unique equivalent circuit in which a second capacitor is connected in parallel to a series circuit,
It is possible to provide a resonator with a high Q that is suitable for filters, oscillation elements, etc. used at frequencies above 400 MHz. Furthermore, since coils are connected in series on both sides of one capacitor, multiple resonators can be magnetically coupled without using a separate coupling means. It has a remarkable effect of being very beneficial.

[Brief explanation of the drawing]

Figure 1 is an equivalent circuit diagram of the resonator of the present invention, Figure 2 A is a front view of the resonator of an embodiment of the present invention, Figure 2 B is a side view of the resonator of Figure A, and Figure 2 H is a side view of the resonator of Figure A. is a rear view of the resonator in Figure A, Figure 3 is a resonance characteristic diagram of the resonator, Figure 4 is a front view of an example of magnetic coupling using three resonators, and Figure 5 A and B are conventional examples, respectively. FIG. 2 is an equivalent circuit diagram of a resonator of FIG. A, B, C...resonator, C1...first capacitor, C2...second capacitor, L1, L2...
... Coil, 1 ... Dielectric substrate, 2a, 2b, 3
a, 3b...capacitor electrode pattern, 4a, 5
a...Coil pattern.

Claims (1)

[Claims] 1. A resonator comprising a coil and a capacitor, and having an equivalent circuit in which a second capacitor is connected in parallel to an LC series circuit in which the coils are connected in series on both sides of the first capacitor.