JPH02241202A - Filter device - Google Patents

Abstract

PURPOSE:To constitute a filter device so that the sufficient attenuation quantity can be attained even if it is miniaturized by connecting in series plural dielectric coaxial resonators through a first capacitor, and also, connecting in parallel a series connecting body of a second capacitor, a strip line and a third capacitor to a first capacitor. CONSTITUTION:This filter device is constituted of a lambda/4 dielectric coaxial resonator 1, a dielectric substrate 2 for constituting a strip line 7 and input/output coupling capacitors 8a, 8b, a coupling substrate 3 for constituting a coupling capacitor 6 on an alumina substrate, a lead wire for connecting the lambda/4 dielectric coaxial resonator 1 and the coupling substrate 3, and a transmission terminal 5. On the dielectric substrate 2, through-holes 9a, 9b and 9c of the lead wire 4 are provided. Also, on the surface of this dielectric substrate 2, an input electrode 10a, an output electrode 10b and an electrode 11 for forming the strip line 7 are provided by performing silver metallizing, etc. The input coupling capacity is formed by the input electrode 10a and the electrode 11 for the strip line 7, and the output coupling capacity is formed by the output electrode 10b and the electrode for a strip line 11.

Description

[Detailed description of the invention] Industrial applications 2 Heno The present invention relates to a filter device.

2. Description of the Related Art A conventional filter device is shown in FIG. 4. Conventionally, one λ/4 dielectric coaxial resonator shown in FIG. 4 was connected to a coupling capacitor board 3A via a lead wire 4A. . or,
The input/output transmission terminal 5A was connected to the coupling capacitor board 3A.

Problems to be Solved by the Invention However, with the above configuration, when the size is reduced, the L component also becomes smaller, and a sufficient amount of attenuation cannot be obtained. Therefore, it is an object of the present invention to provide a sufficient amount of attenuation even when downsized.

Means for Solving the Problems In order to achieve the above object, the present invention (j:, a plurality of dielectric coaxial resonators are connected in series via a first capacitor, and a second capacitor is connected to the first capacitor. A series connection body of a capacitor, a strip line, and a third capacitor are connected in parallel.

If the configuration exceeds the effect, the transmission waveform of the filter will be low 3...-
Since traps can be created in the 7 and high frequencies, sufficient attenuation can be achieved even when downsized.

Embodiment FIG. 1 is a circuit diagram of a filter device according to an embodiment of the present invention. In FIG. 1, 1 is a λ/4 dielectric coaxial resonator, 6 is a coupling capacitor, 7 is a strip line, sa
, sb are input/output coupling capacitors of the strip line 7.

FIG. 2 is a structural diagram of a filter device according to an embodiment of the present invention. In FIG. 2, 1 is a λ/4 dielectric coaxial resonator, 2 is a strip line 7 and an input/output coupling capacitor 81.
L, 8b is a dielectric substrate, 3 is a coupling board with a coupling capacitor 6 formed on an alumina substrate, 4 is a lead wire connecting the λ/4 dielectric coaxial resonator 1 and the coupling substrate 3, 5
is a transmission terminal.

3a and 3b show the dielectric substrate 2, in which through holes 9a, 9b, 90 for the lead wires 4 are provided. Further, on the surface of this dielectric substrate 20, electrodes 11 for forming the input electrode 10a and the output type 4i10b+strip line 7 are formed by silver metallization or the like. The input coupling capacitance is the input electrode 10a and the electrode 1 for strip line γ.
1, and the output coupling capacitance is output type % 1c)
(b) and (c) are formed by electrodes for the IJ tube line 11.

By varying this input/output coupling capacitance, the position of the trap can be varied. Further, the length of the strip line electrode 11 is given by (9X 10 )/(4XFXv'FF) (F: center frequency of the filter, εr: relative dielectric constant of the dielectric substrate). Further, on the back surface of the dielectric substrate 2, an electrode 12 for forming a ground electrode is provided by silver metallization or the like.

Effects of the Invention As described above, according to the present invention, a plurality of dielectric coaxial resonators are electrically connected in series via a first capacitor, and a second capacitor and a strip are connected to the first capacitor. Since the series connection body of the line and the third capacitor are connected in parallel, it is possible to provide a small filter device with high attenuation.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a filter device according to an embodiment of the present invention, FIG. 2 is a perspective view of a filter device according to an embodiment of the present invention, and FIGS. The front view and back view of the dielectric substrate according to the example, and FIG. 4 are perspective views of the filter device according to the conventional example. 1... λ/4 dielectric coaxial resonator, 2...
・Dielectric substrate, 3...Coupling capacitor substrate, 4.
...Lead wire, 6. River... Coupling capacitor (, I
Nl conte 7t), 7... strip line, 8a, 8b... input and output coupling capacitors (second and third capacitors).

Claims (2)

[Claims] (1) A plurality of dielectric coaxial resonators are electrically connected in series via a first capacitor, and a second capacitor, a strip line, and a third capacitor are connected to the first capacitor.
A filter device in which series-connected capacitors are electrically connected in parallel. (2) A plurality of dielectric coaxial resonators are arranged in parallel on a first substrate, a second substrate having a strip line is arranged between the first substrate and the dielectric coaxial resonators, and A lead wire from the first dielectric coaxial resonator to the first substrate is electrically connected to one end of the strip line of the substrate, and a lead wire from the second dielectric coaxial resonator to the other end of the strip line is electrically connected to the strip line from the first dielectric coaxial resonator to the first substrate. 1
2. The filter device according to claim 1, wherein a lead wire directed toward the substrate is electrically connected.