JPS63220603A - Ceramic waveguide filtering circuit - Google Patents

Abstract

PURPOSE:To simplify a manufacturing process and to decrease a transmission loss by executing a conductive film approximately to the whole circumferential surface of a ceramic bar-shaped body, forming the waveguide of a transmitting area and an interrupting area and obtaining a necessary filtering characteristic with a conductive body element only to extend in the direction orthogonal to one side surface. CONSTITUTION:For example, at the whole circumferential surface of four side surfaces and both edge surfaces in a ceramic bar-shaped body 1 of a square cross section, a conductive body coat 2 is executed. The conductive body element to extend in the direction orthogonal to the shaft of the ceramic bar-shaped body 1 is formed. Thus, the ceramic bar-shaped body 1, in which the whole circumferential surface is approximately covered by the conductive body coat 2, is operated as an interrupting waveguide to the microelectromagnetic wave of a frequency area not to exceed the interrupting frequency determined by the shape dimension of the cross section. Consequently, to the whole circumferential surface of the ceramic bar-shaped body 1, the conductive body coat 2 is executed, a conductive body element idly separated from the circumferential surface conductive body coat 2 to both edge parts is penetrated in the direction orthogonal to the shaft and only made into input output combining elements 3 and 4, and therefore, the circuit can be easily constituted.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a ceramic waveguide that selectively propagates microwaves in a desired frequency range within a miniaturized waveguide whose internal space is filled with a dielectric. Regarding the type filter circuit, in particular, the structure is not only simplified and manufactured easily, but also high performance equivalent to or higher than that of the conventional filter can be obtained.

(Prior Technology) Conventionally, this type of ceramic waveguide type filter circuit has been constructed by applying a conductive coating to the entire outer circumferential surface of a ceramic rod except for one end surface, and by penetrating a small hole in the axial direction in the center. A coaxial filter circuit is constructed by arranging a plurality of Z-wavelength coaxial tuning circuits whose inner peripheral surfaces are also coated with a conductive material in the direction of electromagnetic wave propagation in the waveguide system, and sequentially capacitively coupling the central conductor portions of each circuit. It was used.

(Problems to be Solved by the Invention) However, in the conventional coaxial filter circuit described above, the structure for obtaining capacitive coupling of the center conductor portions between the coaxial tuned circuits is complicated, and it takes time and effort to manufacture it. In addition, there were problems in that the Q value of the ceramic coaxial circuit could be sufficiently large, resulting in increased transmission loss.

(Means for Solving the Problems) An object of the present invention is to solve the above-mentioned conventional problems, simplify the coupling structure between elements in the direction of electromagnetic wave propagation in a waveguide system, and make manufacturing much easier than in the past. It is an object of the present invention to provide a ceramic waveguide type filter circuit which can reduce transmission loss.

That is, in the ceramic waveguide type filter circuit according to the present invention, a conductive coating is applied to almost the entire circumferential surface of a ceramic rod-shaped body to form a waveguide in a transmission region or a cutoff region. By not providing any conductive elements extending in the axial direction, but by ensuring that the required filtering characteristics are obtained only by the conductive elements extending in the direction orthogonal to the side surfaces,
This method significantly simplifies the manufacturing process and reduces transmission loss, and a conductive material coating is provided over almost the entire side and both end surfaces of a ceramic rod-shaped body of a predetermined length and a cross section of a predetermined shape and size. to form a waveguide forming a propagation region or a cutoff region depending on the shape and size of the cross section,
Input/output coupling elements each made of a conductor element having a predetermined shape are provided at both ends of the waveguide, and the shape and size of the conductor coating in the cross section of the ceramic rod-shaped body or the It is characterized by selectively propagating electromagnetic waves in a frequency range corresponding to periodic changes in shape and dimensions in the tube axis direction.

(Function) Therefore, according to the present invention, a ceramic waveguide type filter circuit having excellent filtering performance can be manufactured extremely easily.

(Example) The present invention will be described in detail below with reference to the drawings.

First, as an example of the simplest configuration of the ceramic waveguide filter circuit of the present invention, a high-pass filter circuit is shown in FIG.
). In the illustrated configuration example, a conductor coating 2 is applied to the entire circumferential surface of the west side and both end surfaces of a ceramic rod-shaped body 1 having a rectangular cross section and having a length necessary to obtain a sufficient amount of cutoff attenuation. At both ends of the two side surfaces A and B, as shown in FIG. 1(b), the conductor coating 2 in minute areas is removed, the exposed ceramic rod-shaped body 1 is penetrated with pores, and the inside of the pores is penetrated. A conductive element extending in a direction perpendicular to the axis of the ceramic rod-shaped body 1 is formed by applying a conductive coating to the circumferential surface, and the conductive elements at both ends are used as input/output coupling elements 3 and 4 as external conductors. Connect to each wave path.

As mentioned above, the ceramic rod-shaped body 1 whose almost entire circumferential surface is covered with the conductive film 2 acts as a cut-off waveguide for microelectromagnetic waves in a frequency range that does not exceed the cut-off frequency determined by the shape and dimensions of its cross section. However, it acts as a normal waveguide for microelectromagnetic waves in a frequency range exceeding its cutoff frequency. Therefore, a conductive coating 2 is applied to the entire circumferential surface of a ceramic rod-shaped body 1 having an appropriate shape and dimensions, and conductive elements separated from the circumferential conductive coating 2 are passed through both ends in a direction perpendicular to the axis. Input/output connection element 3,
A microwave high-pass filter circuit can be obtained with an extremely simple and easy-to-manufacture configuration of only 4.

FIG. 2(a) shows an example of the configuration of the filter circuit of the present invention, which is a low-pass filter circuit that is somewhat more complex than the one described above but is similarly easy to manufacture. In the illustrated configuration example, the shape and dimensions of the cross section of the ceramic rod-shaped body 1, which is configured almost in the same manner as the configuration example shown in FIG. At the same time, as shown in FIG. 2(b), on the two opposing sides A and B through which the conductor element forming the input/output coupling element 3.4 passes, recesses of appropriate shapes and dimensions, for example, the same one-sided shape, are formed. 5a and 5b are arranged facing each other in an axial matrix,
A conductive coating 2 is applied to almost the entire circumferential surface of the ceramic rod-shaped body 1, including the inner circumferential surfaces of the recessed notches 5a and 5b.

In the ceramic rod-shaped body 1 having such a configuration, the capacitance C is between the opposing bottom surfaces of the opposing recessed portions 5a and 5b.
At the same time, the protrusions between adjacent recessed portions act as an inductance L. Therefore, a plurality of inductance elements are connected in series on two opposite sides A and B between the input/output coupling elements 3.4 at both ends, and a plurality of inductance elements are connected in parallel between the interconnection points of the inductance elements. It is possible to exhibit low-pass filtering characteristics equivalent to a four-terminal circuit network in which capacitive elements C are respectively connected.
, 5b can be appropriately set to easily manufacture a low-pass filter circuit having desired filtering characteristics.

Therefore, the ceramic waveguide of the present invention when the high pass band in the configuration example of the high-pass filter circuit shown in FIG. 1 is given a notch characteristic as shown in FIG. 3(b). An example of the configuration of a tube filter circuit is shown in FIG. 3(a). The illustrated configuration example is a cross-sectional view of the E-plane of a ceramic rod-shaped body 1 whose entire circumference is coated with a conductive material and whose shape and dimensions act as a blocking area for low-frequency electromagnetic waves, just like the configuration example shown in FIG. The cutoff wavelength λ in the passband characteristic whose surface width is shown in FIG. 3(b). At the same time, a pore 6 in the direction perpendicular to the tube axis is passed through between the two opposing sides A and B, moving toward one side edge C, and the pore 6 is By applying a conductive film to the inner circumferential surface of each pore 6 to a height of C/4 with respect to the notch frequency ft, as shown in FIG. A notch at a desired frequency f is inserted into the band.

In the configuration example shown in FIG. 3, the conductive element 6 for making a notch in the passband is placed on the inner periphery of a pore penetrating the ceramic rod-shaped body 1, similar to the example of the input/output coupling element 3.4. The notch conductor element 6 and the input/output coupling element 3.4 are both formed by applying a conductive film to the side edge C and both end faces of the ceramic bar body. FIG. 4 shows an example of the configuration of the filter circuit of the present invention in which the filter circuit is formed to be used in combination, and the configuration is significantly simplified and manufacturing is further facilitated. In the illustrated configuration example, a conductive coating 2 is applied to the side edge C and both end surfaces of the ceramic rod-shaped body 1.
The notch conductive element 6S and the input/output coupling element 3S are cut out as shown in the figure to separate them into appropriate shapes and dimensions.

4S is formed in the shape of a strip line so as to exhibit almost the same pass band characteristics as the configuration example shown in FIG. A microwave notch filter having the required passband characteristics can be obtained by an extremely simple process of just depositing the coating 2.

Next, similar to the high-pass and low-pass filter circuits described above, a ceramic rod-shaped body 1 is provided with a conductive coating 2 on almost its entire circumference and input/output coupling elements 3.4 at both ends. By arranging conductor elements that extend perpendicularly to the waveguide axis in a variety of configurations along the direction of electromagnetic wave propagation, microwave communication devices can be developed. The configuration of the ceramic waveguide type filter circuit of the present invention when used as a frequently used band-pass filter circuit is shown in FIGS. 5 to 10.

First, an example of the basic configuration of a ceramic waveguide type bandpass filter circuit according to the present invention is shown in FIG. The illustrated configuration example is
Between the input/output coupling elements 3.4 at both ends of the cut-off waveguide formed by the ceramic rod-shaped body 1 having a rectangular cross-section whose almost entire circumferential surface is covered with a conductive film 2, two opposing side surfaces A, perpendicular to the axis; A conductive element 6 extending between B and having a length of approximately λ, /4 is preferably connected to
By arranging them in the axial direction at intervals of . It is preferable to form the ceramic rod-shaped body 1 by applying a conductive coating to the inner circumferential surface of the pore passing through it.

By the way, the mode of electromagnetic wave propagation in a trough-type waveguide in which a trough is provided in the tube axis direction along the centerline of the E-plane of a rectangular waveguide is always relative to the centerline of the E-plane. It becomes symmetrical. Therefore, when the bandpass filter circuit shown in FIG.
As shown in the figure, a notched groove 7 in the tube axis direction is formed on, for example, a side surface A of a ceramic rod-shaped body 1 having a rectangular cross section, and input/output coupling elements 3.4 are provided at both ends of the notched groove 7. Yo·
In this way, a conductive coating 2 is applied to the entire circumferential surface of the ceramic rod-shaped body 1, including the inner circumferential surface of the notched groove 7, and conductive elements 6 are arranged symmetrically on the left and right side surfaces A that sandwich the notched groove 7. I will do it.

In the trough-type conductive tube, as mentioned above, electromagnetic waves propagate symmetrically with respect to the center line of the E plane. Electromagnetic waves can be propagated in exactly the same way using only one of the half-cut waveguides. Therefore, the sixth
The illustrated configuration example is divided into one segment along the notched groove 7, and the conductive element 6 provided in the ceramic rod-shaped body 1 of the illustrated left half waveguide is, for example, taken as the configuration example illustrated in the fourth figure. It is also possible to cut out a part of the conductor coating 2 applied to the mounting surface along the groove 7 and provide it on the cut surface.

FIG. 7 shows an example of the configuration of a bandpass filter circuit according to the present invention in the form of such a half-cut waveguide. In the illustrated configuration example, the ceramic rod-shaped body 1 of the trough-type waveguide shown in FIG.
A conductive film having a pattern corresponding to the input/output coupling elements 3 and 4 and the conductive element 6 for bandpass filtering shown in the figure is provided. That is, a strip-shaped conductor coating is formed in a direction perpendicular to the tube axis at the position where the conductor coating 2 is partially removed at both ends of the side surface A of the half-cut ceramic rod-shaped body 1, and the input/output coupling element 3.4 is formed. , a conductor coating 2 in which a strip-shaped conductor coating 6S is formed in a direction perpendicular to the tube axis at a position corresponding to the conductor element 6, and both ends of the band-shaped conductor coating 6S are attached to the upper and lower side surfaces A and B.
A slit 8 is provided in the intermediate portion to form a capacitor C, and the capacitor C is adjusted by the slit width to change the filtering characteristics of the strip-shaped conductive film 6S that acts as a slow wave circuit element. Further, adjacent strip-shaped conductor coatings 6
In the middle of S, a strip-shaped conductive film 9 is formed in the direction perpendicular to the tube axis by connecting both ends to the conductive films 2 on the upper and lower sides A and B, and separates each stage of the slow wave circuit. The degree of mutual coupling can be adjusted by adjusting the film width, and bandpass filtering characteristics equivalent to the configuration example shown in FIG. 6 can be obtained by such a conductive pattern on the cut surface. Note that if the dielectric constant of the ceramic rod-shaped body 1 is sufficiently large, the conductor pattern on the cut surface acts in the same manner as a strip line, so that almost no electric field radiation leaks from the conductor pattern.

Next, in the configuration example shown in FIG. 7, in order to separate each stage of the slow-wave circuit and adjust the degree of coupling between them, instead of forming the strip-shaped conductive film 6S on the cut surface, the band-shaped conductive film 6S is formed on the opposite side surface. FIG. 8 shows an example of a configuration in which a recessed portion 10 is formed in a direction perpendicular to the tube axis. In the illustrated configuration example, ' is a rectangular recessed part, for example, at a position corresponding to the band-shaped conductor coating 6S on the side surface of the ceramic rod-shaped body facing the cut section provided with the conductor pattern for obtaining band-pass filtering characteristics. The degree of bonding between the band-shaped conductor coatings 6S can be adjusted depending on the shape and size of the conductor coatings.

However, if the dielectric constant of the half-cut ceramic rod-shaped body 1 is sufficiently large, as described above, the half-cut ceramic rod-shaped body 1
Even if a conductor pattern as shown in FIG. 7 or 8 is formed on the cut surface of the ceramic bar, almost no leakage electric field radiation occurs, but if the dielectric constant of the half-cut ceramic bar 1 is not large enough, It is necessary to suppress leakage electric field radiation from the cutting section. Examples of the configuration of the filter circuit of the present invention in such a case are shown in FIGS. 9 and 10, respectively.

In each illustrated configuration example, in order to reduce leakage electric field radiation from the gap between the conductor patterns shown in FIG. 7 or 8 in the cut section of the half-cut ceramic rod-shaped body 1,
Similar to the conductive film 2 applied to the other side surfaces, a continuous conductive film 11 is provided on the cut surface to localize the aforementioned conductive pattern, and in the configuration example shown in FIG. The conductive pattern portion is provided along the underline of the cut section, and in the configuration example shown in FIG. 10, it is provided in the central region sandwiched between continuous conductive films 11 and 12, respectively.

(Effects of the Invention) As is clear from the above description, according to the present invention, various frequency band selection means are applied to the ceramic conductive tube, which is miniaturized by filling the internal space with a dielectric material, to selectively transmit microwaves. Not only is it possible to easily manufacture a ceramic waveguide type filter circuit that allows propagation to occur due to its extremely simple configuration and structure, but it also has the exceptional effect of providing excellent filtering characteristics that are equal to or better than conventional ones. .

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are a perspective view and a partial longitudinal sectional view respectively showing a configuration example of a ceramic waveguide type filter circuit of the present invention as a high-pass filter circuit, and FIGS. 2(a) and 1(b) are
) is a perspective view and a longitudinal cross-sectional view respectively showing an example of its configuration as a low-pass filter circuit, and FIGS. 3(a) and (c) are an example of its configuration as a knock filter and an example of its frequency characteristics, respectively. FIG. 4 is a perspective view showing another example of the configuration as a notch filter, FIG. 5 is a perspective view showing an example of the configuration as a bandpass filter circuit, and FIG. Similarly, FIGS. 7 to 10 are perspective views showing other configuration examples of the band-pass filter circuit, respectively. FIGS. 1...Ceramic rod-shaped body 2...Conductor coating
3, 4... Input/output coupling elements 5a, 5b... Recessed portion 6... Conductor element 3S, 43.6S, 9... Band-shaped conductor coating 7.
...Trough 8...Slit 10...
Concave cutout 11.12...Conductor coating 7th
Figure 8 Figure 9 Figure 1O Figure

Claims (1)

[Scope of Claims] 1. A conductive material coating is provided over almost the entire side surface and both end surfaces of a ceramic rod-shaped body of a predetermined length having a cross section of a predetermined shape and size, and a propagation region or a block is formed depending on the shape and size of the cross section. A waveguide is formed, and input/output coupling elements each made of a conductor element of a predetermined shape are provided at both ends of the waveguide. 1. A ceramic waveguide type filter circuit, characterized in that electromagnetic waves in a frequency range corresponding to the shape and size of a conductor coating on a surface or periodic changes in the shape and size in the tube axis direction are selectively propagated. 2. Setting a cutoff frequency of the waveguide depending on the shape and size of the cross section of the ceramic rod, and selectively propagating electromagnetic waves in a frequency range exceeding the cutoff frequency between the input/output coupling elements. A ceramic waveguide type filter circuit according to claim 1, wherein the ceramic waveguide type filter circuit is a high-pass filter circuit. 3. The shape and dimensions of the conductor coating in the cross section of the ceramic rod-shaped body are periodically changed in the tube axis direction, and electromagnetic waves in a frequency range corresponding to the period of change in the shape and dimension are transmitted between the input and output coupling elements. 2. The ceramic waveguide type filter circuit according to claim 1, wherein the ceramic waveguide type filter circuit is made into a band pass filter circuit by selectively propagating the waveguide. 4. The shape and dimensions of the conductor coating extending from a side area near a predetermined one side line of the ceramic rod-like body to the side surface area and on the concave cut surface or side surface of the ceramic rod-like body are determined. A bandpass filter circuit is formed by selectively propagating electromagnetic waves in a frequency range that corresponds to the cycle of changes in the shape and dimensions by changing them periodically in the axial direction between the input and output coupling elements. A ceramic waveguide filter circuit according to claim 3. 5. A conductive coating element extending from a side surface area near a predetermined one side line of the ceramic rod-like body on the concave cutout surface or side surface of the ceramic rod-like body substantially perpendicularly to the side surface area in the tube axis direction. A bandpass filter circuit is formed by arranging the input/output coupling elements at equal intervals and selectively propagating electromagnetic waves in a frequency range corresponding to the equal intervals between the input/output coupling elements. The ceramic waveguide filter circuit according to item 3. 6. At least one row of recessed portions having substantially the same shape and dimensions are arranged facing each other at equal intervals in the tube axis direction on both corresponding side surfaces of the ceramic rod-shaped body having a rectangular cross section, and the shape and size of the recessed portions are adjusted. Claim 1, characterized in that a low-pass filter circuit is created by selectively propagating electromagnetic waves in a frequency range that does not exceed a cutoff frequency determined by the spacing between the input and output coupling elements. Ceramic waveguide filter circuit.