JPS60145704A - Dielectric filter - Google Patents

Abstract

PURPOSE:To prevent degradation of frequency characteristics by separating a dielectric substrate, where an input/output line constituted with microstrip lines is formed, and a substrate holding a dielectric resonator from each other. CONSTITUTION:Dielectric resonators 2 are held on a metallic plate 17 through dielectric substrates 11 having a low dielectric constant. Input/output parts 12 and 13 of the input/output line constituted with microstrip lines are formed on a dielectric substrate 10. For the purpose of extending the interval between coupling parts 14 and 15 of the input/output line, coupling parts are bent at right angles to input/output parts 12 and 13 and substrates 10 and 11 are separated from each other and are arranged and fixed. An end part (c) of the dielectric substrate 10 is cut while leaving a length (d) shorter than a used line width W as it is to couple the coupling part 14 and the dielectric resonator more close, thus obtaining characteristics having a wide fractional band.

Description

Detailed Description of the Invention (81) Technical Field of the Invention The present invention relates to a dielectric filter, and more particularly to a coupling section of an input/output line composed of a microwave integrated circuit coupled to a dielectric resonator. .

(b) Conventional technology and problems Recently, dielectric materials have been actively developed, and it has become possible to obtain materials with low loss and good temperature characteristics in the frequency band ranging from microwaves to millimeter waves. .

Conventionally, resonators in high frequency bands have been large and heavy cavity resonators or coaxial resonators using metal containers.

On the other hand, recent dielectric resonators are small and lightweight, have a simple structure, and have low processing and material costs, so they can stabilize filters and oscillators in frequency bands ranging from microwaves to millimeter waves. It has come to be widely used as a vessel.

FIG. 1 shows the electromagnetic field distribution depending on the shape of the dielectric resonator used and its fundamental resonance mode.

As shown in the figure, the shapes of the dielectric resonators are mainly cylindrical and cubic. Its dimensions vary depending on the resonant frequency, for example Aγ with a resonant frequency of 20GIIz
The square dielectric resonator has a diameter of approximately 3×3× (1-1
, 5) mm.

Also, as shown in the figure, the electromagnetic field distribution is the same for both the cylindrical and cubic shapes, but in the former case, the TEo1r moat, f&8
In this case, it is called TEn6 mote.

In the figure, ■ indicates a state in which the electric field passes from the top to the bottom of the paper, and ■ indicates the opposite.

Figure 2 is a diagram for explaining the arrangement of dielectric resonators when the input/output section is a waveguide. It is a figure when each is removed.

In the figure, ■ indicates a standard waveguide section with a width in the middle x a length in the middle, 2 indicates a cylindrical dielectric resonator, and 3 indicates a cutoff waveguide section with a width ax and a length B.

In Fig. 2 tel, the waveguide moat propagating through the standard waveguide section 1 with width AX and length B is blocked by the blocking waveguide section 3 with width a and length B, and propagates therein. I can't do it.

However, only waves that resonate with the dielectric resonators 2 arranged and fixed in this cut-off waveguide section 3 can pass through this cut-off waveguide section 3.

Figure 3 is a diagram for explaining a conventional example of a dielectric resonator in which the input/output line portion is composed of a microstrip line.
Figure (al is the plan view, Figure 3 (bl is A of Figure 3 tal)
-X cross-sectional views are shown respectively.

In the figure, 4 indicates, for example, an alumina substrate, 2 indicates a dielectric resonator, 5 indicates a microstrip line obtained by depositing a metal such as gold, and 6 indicates a ground conductor surface whose entire surface is coated with metal. .

As shown in FIG. 3, dielectric resonators 2 are arranged and fixed on one dielectric substrate 4, and input/output lines 5 and 7 coupled to the dielectric resonators are formed. Ru. The microstrip lines 5 and 7 are magnetically coupled to the dielectric resonator 2 at a line length distance of approximately λg/4 from the open portion with respect to a desired center frequency to form a dielectric filter.

Figure 4 is a diagram showing the frequency characteristics of the dielectric filter shown in Figure 3.As shown by the solid line, attenuation (i;) decreases at higher frequencies, and resonance due to spurious moat can be seen at point b. .

This is because when the frequency increases, a part of the electromagnetic wave applied to the input line propagates through the dielectric resonator, which is the normal propagation path, inside the dielectric substrate 4, or on the human-powered line 5. This is because the signal is propagated from the tip to the tip of the output line 7, which has a narrow interval.

Therefore, a dielectric filter constructed using a microstrip line on a single dielectric substrate has a problem in that desired attenuation characteristics cannot be obtained as the frequency increases.

On the other hand, if the order of the filter is small, the number of dielectric resonators used will be small, and similar problems will occur.

tel Object of the Invention The present invention has been made in view of the problems of the prior art described above.
Structure of the Invention The object of the above invention is to provide at least one (fli
In a dielectric filter in which a dielectric resonator using a TEalE (TE++δ) moat of t or more and a coupling part of a human output line that magnetically couples with the dielectric resonator are arranged and fixed, a microstrip line is used. A dielectric filter characterized by having a structure that separates a dielectric substrate on which a coupling part of the input/output line is formed and a low dielectric constant dielectric substrate holding the dielectric resonator. This is achieved by providing a vessel.

tel Embodiments of the Invention As mentioned above, the present invention is configured to minimize direct coupling between coupling parts of input/output lines and within a dielectric substrate, which causes deterioration of the frequency characteristics of a dielectric resonator. This is what I did.

A-X cross-sectional views of each are shown.

In the figure, 2 is a dielectric resonator, 10 is a dielectric substrate, and 1 is a dielectric resonator.
12 and 13 are the human output parts of the input/output lines; ■4 and 15 are the coupling parts of the human output lines;
Reference numeral 6 indicates a ground conductor surface, and reference numeral 17 indicates a metal plate.

In the figure, in order to widen the distance between the coupling parts 14 and 15 of the input/output lines, the coupling parts are connected to the input/output parts 121 (and 1) of the input/output lines.
A dielectric substrate (e.g., alumina substrate) 10 on which input/output lines are formed, and a low-permittivity dielectric substrate (e.g., quartz) II holding the dielectric resonator. They are arranged and fixed separately.

FIG. 6 is an enlarged view of the joint part, FIG. 6(8) is a plan view, and FIG. 6+b) is a sectional view taken along line A-X in FIG. Note that the symbols in the figure are the same as those in FIG.

In the same figure, by cutting the end C of the dielectric substrate IO leaving a spacing d narrower than the width W in the line used there, the coupling between the coupling part 14 and the dielectric resonator becomes denser, and A characteristic with a large band can be obtained.

FIG. 7 shows another embodiment of the present invention, in which the leads of the input and output lines are evenly spaced from each other to widen the interval between the coupling parts of the input and output lines.

Incidentally, the frequency characteristics of the dielectric filter shown in FIGS. 5 and 7 are shown by the dotted line in FIG. 4, and better characteristics were obtained compared to the conventional filter.

As described in detail, the present invention provides a structure that separates the II opening 1 between the coupling portion of the human power line and the output line that are coupled to the dielectric resonator, and also provides a low dielectric constant for holding the dielectric resonator. The dielectric substrate and the dielectric substrate forming the coupling portion of the input/output line are separated to reduce the coupling of undesired electric value waves.

On the other hand, by cutting the end of the dielectric substrate while leaving a narrower width, the coupling between the coupling part and the dielectric resonator is strengthened, resulting in a dielectric with good frequency characteristics. I was able to get body filtering.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining the shape of a dielectric resonator, and Figure 2 is a diagram for explaining the shape of a dielectric resonator.
The figure is a diagram for explaining the arrangement of dielectric resonators when the input/output section is a waveguide, and Figure 3 is a diagram for explaining the arrangement of dielectric resonators when the input/output line section is a microphone II strip line (conventional method for resonators). Figure 4 is a diagram for explaining an example of the configuration of Figure 3 and Figure 6 or Figure 7.
5 shows an embodiment of the present invention, FIG. 6 shows an enlarged view of the coupling part of the human output line in FIG. 5, and FIG. 7 shows the characteristics of the dielectric filter shown in FIG. Another embodiment of the present invention is shown in the figure "2", "2" is a dielectric resonator, "1o" is a dielectric substrate, and "II" is a dielectric resonator.
is a low dielectric constant dielectric substrate, and 12 and 13 are human output lines I?
14 and 15 are input/output line coupling parts, 16 is a ground conductor surface, and 17 is a metal plate. Grass 10 h' Grass 2 Za (12) Figure 1 (I2) Figure 4 Gang J - Autumn Grass 5 Figure α) Grass opening and 4) ' (b) 5 Figure 7

Claims (1)

[Claims] 1. - At least one T E,,i in the electric space
(GOEIIS) A dielectric resonator using a moat and a coupling part of an input/output line that magnetically couples with the dielectric resonator are arranged and
In a fixed dielectric filter, the dielectric substrate on which the input/output line composed of microstrip lines is formed is separated from the low dielectric constant dielectric substrate holding the dielectric resonator. A dielectric filter characterized by having a structure in which 2. A patent characterized in that the input/output line composed of a microstrip line is composed of a coupling part that couples with the dielectric resonator and an input/output part connected at right angles to the coupling part. A dielectric filter according to claim 1. 3. The dielectric substrate on which the input/output line is formed is cut at the end on the side where the input/output line is connected, leaving a width within the line 11 of the input/output line's connecting area.