JPH0481886B2 - - Google Patents

Description

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

Conventional technology and its problems Resonators used in filters, oscillation elements, etc. in the above frequency range are required to have a relatively high sharpness (hereinafter referred to as Q), and such resonators are conventionally , dielectric resonators, strip lines, etc.

However, the former type of resonator (dielectric coaxial resonator) is relatively expensive, and when used as a filter, simply arranging them in parallel does not constitute a circuit, and requires a separate coupling means such as a capacitor. However, there were problems in that the structure was complicated and large, and the assembly work was time-consuming.

On the other hand, the latter resonator (stripline) is
When the operating frequency is low, such as the 400 MHz band, the size becomes large, and since the electrodes are formed on the entire back surface of the substrate, the number of electrode members increases, resulting in an unavoidable increase in cost. In view of these problems, the present invention provides a useful resonator that is small, low cost, and can be coupled to each other without using a separate coupling means such as a capacitor when used as a filter. The purpose is to

Means for Solving the Problems In order to achieve the above object, a resonator according to the present invention has a capacitor electrode pattern formed at two opposing locations on both the front and back surfaces of a dielectric substrate, and a space between the electrode pattern and the capacitor electrode pattern. A dielectric substrate forms first and second capacitors, and a coil pattern is formed between two capacitor electrodes on the front surface of the substrate and between two capacitor electrodes on the back surface of the substrate, and and a coil configured by the coil pattern connected in series on both sides thereof form an LC series circuit, and the second capacitor is connected in parallel to this LC series circuit. It is characterized by

Embodiment FIG. 1 shows the external configuration of a resonator as an embodiment of the present invention, in which Figure A is a front view, Figure B is a side view, and Figure C is a rear view. In the figure, 1 is a dielectric substrate made of, for example, FRDR material, and its front surface 1a and back surface 1b
and have two capacitor electrode patterns 2a,
2b, 3a, 3b and coil patterns 4a, 5a are formed, for example, by screen printing silver paste. The electrode patterns 2a and 3
a, 2b, and 3b face each other on both sides of the dielectric substrate, forming capacitors C1 and C2 having capacities determined by the dielectric constant and thickness of the substrate and the opposing areas of the capacitor electrodes. On the other hand, coil patterns 4a and 5a connect two capacitors to electrode patterns 2a and 2 on each side of the dielectric substrate.
b, 3a and 3b are connected. Each coil pattern 4a, 5a forms a coil in terms of high frequency, so its inductance is L.
1 and L2, the resonator has coils L1 and L2 on both sides of the first end C1, as shown in FIG.
A second capacitor C2 is connected in series to the LC circuit.
It is expressed as an equivalent circuit that connects in parallel.

A resonator with such an equivalent circuit has not existed in the past, and therefore it can be said that the resonator is novel in terms of the equivalent circuit. The two coil patterns 4a and 5a have appropriate lengths to enable magnetic coupling with other resonators, and are formed as close to the edge of the substrate as possible.

Furthermore, the two coil patterns 4a and 5a in the same resonator are spaced apart as much as possible so that they do not magnetically couple or have capacitance.

To make the resonator with the above configuration resonate at fr=504MHz, for example, if C1 is set as C1=18pF, L1 and L2 are given by the following equations.

Here, if L1=L2, then L1=L2=2.77nH. C2 can be selected depending on the impedance used, regardless of the resonance frequency. In this example, when the impedance is 50Ω, C2
= 53pF has the maximum Q, so I chose 53pF.
Here, the dielectric constant ε of the dielectric substrate 1 is 80, and the thickness is
If it is 0.4mm, the capacitance of C1 and C2 is l1=
7 mm, l2 = 1.5 mm, l3 = 7 mm, and l4 = 3.5 mm. Further, the inductances of L1 and L2 are obtained by setting l5=l6=6 mm. Width W1 of coil patterns 4a, 5a,
Although W2 is not related to the inductance value, the larger the width, the smaller the resistance, and therefore the higher the Q, which is preferable. In this example, W1=W2=
It is set to 1.5mm. FIG. 3 shows the resonance characteristics when the other dimensions (l1, l2...l6) and the ε and thickness of the dielectric substrate 1 are as described above. In this case, Q is 148
A very high value was obtained.

As for the reason why such a high Q was obtained,
Although it is a speculation, the above resonator has a unique circuit configuration not seen in the past in terms of an equivalent circuit, the width of the coil patterns 4a and 5a is widened to lower the resistance, and the dielectric substrate 1 is thought to be due to the use of FRDR material.

In the above resonator, the capacitor electrode pattern and the coil pattern are formed in the same pattern on both the front and back surfaces of the substrate. 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 has a thickness of 0.4
mm thickness is used, but by changing the thickness, the capacitance of capacitors C1 and C2 changes and the resonant frequency can be changed, so if you select an appropriate thickness in relation to the frequency of use, good.

Effects of the Invention As explained above, according to the present invention, a resonator has a unique equivalent circuit in which a second capacitor is connected in parallel to an LC series circuit in which coils are connected in series on both sides of a first capacitor. Because there is
It has a high Q that is suitable for filters and oscillation elements used at frequencies above 400MHz, and requires less electrode material than conventional products, making it possible to reduce size and cost. Furthermore, since the capacitor electrode pattern and the coil pattern are formed with the same pattern on both the front and back surfaces of the dielectric substrate, a printing mask with the same pattern can be used during manufacturing, improving productivity. Furthermore, if each coil pattern is formed near the edge of the substrate, by connecting multiple substrates, it is possible to easily magnetically couple the coil patterns of adjacent resonators, making it much easier to install the filter than in the past. Can be configured.

In addition, unlike a dielectric coaxial resonator, the capacitance of the capacitor, which is a component of the resonator, can be changed and adjusted independently, making impedance matching easier.

[Brief explanation of the drawing]

FIG. 1A is a front view showing a resonator as an embodiment of the present invention, FIG. 1B is a side view, FIG. 1C is a rear view, and FIG. 2 is a diagram showing an equivalent circuit of the resonator. FIG. 3 is a diagram showing the resonance characteristics of the resonator. C1...First capacitor, C2...Second capacitor, L1, L2...Coil, 1...Dielectric substrate, 2a, 2b, 3a, 3b...Capacitor electrode pattern, 4a, 5a...Coil pattern .

Claims (1)

[Claims] 1 Capacitor electrode patterns are formed at two opposite locations on the front and back surfaces of the dielectric substrate, and the electrode patterns and the dielectric substrate between them form first and second capacitors, while the surface of the substrate A coil pattern is formed between two capacitor electrodes located on the back surface of the first capacitor and between two capacitor electrodes located on the back surface thereof, and the coil is constituted by the first capacitor and the coil pattern connected in series on both sides of the first capacitor. and forming an LC series circuit, and the second capacitor is connected in parallel to the LC series circuit.