JPH051122Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to improvements in dielectric filters used in satellite communications, car telephones, and other communication equipment in the microwave band.

(Summary of the invention) The present invention is a dielectric filter used in microwave band communication equipment, etc., in which slits are formed in each end face where the open end and short-circuited end of the through-conducting part of the dielectric filter are located, and the through-conducting This structure uses both inductive coupling and capacitive coupling for the coupling between the resonators formed around the section, thereby improving both the high-frequency side and low-frequency side attenuation characteristics.

(Background of the invention) The inventor of the present invention discovered that when a slit is formed in the end face of a dielectric filter where the open end of the through-hole conductive portion is located, the coupling between the resonators formed around the through-hole conductive portion becomes inductive. When a bandpass filter is obtained and a slit is formed in the end face where the short-circuited end of the through-hole conductive part is located, a band-pass filter in which the coupling between each resonator formed around the through-hole conductor becomes capacitive can be obtained. I found out.

(Problem to be solved by the invention) By the way, if a slit is formed only on the open end surface where the open end of the through-conducting part of the dielectric filter is located and inductive coupling is established between each resonator, the height of the bandpass filter will increase. The attenuation characteristic on the high frequency side becomes a characteristic that cuts off sharply (sharp), but the low frequency side deteriorates and becomes a slow (broad) characteristic, which tends to make the bandpass characteristic asymmetrical.

In addition, if a slit is formed only on the short-circuit end face where the short-circuit end of the through-conducting part of the dielectric filter is located, and capacitive coupling is established between each resonator, the attenuation characteristic on the low frequency side of the bandpass filter becomes steep. However, the high frequency side deteriorates and becomes slow (broad), and the bandpass characteristics tend to be asymmetrical.

(Means for Solving the Problems) In view of the above points, the present invention forms slits on both end surfaces (open end surface and short circuit end surface) of the dielectric block where the open end and short circuit end of the through conductive part are located. As a result, a dielectric filter with good high-frequency and low-frequency attenuation characteristics can be created by using both inductive coupling and capacitive coupling for the coupling of the resonator formed around each through-conducting part. This is what we are trying to provide.

The present invention provides four side surfaces of a dielectric block in which three or more through conductive parts formed by forming conductive films on the inner surfaces of a plurality of through holes are arranged side by side at intervals, and a short-circuited end face where one end of the through conductive parts is located. In the dielectric filter, a slit having no conductive film is formed on the open end surface between the open ends of at least one set of adjacent through-hole conductive parts among the three or more through-hole conductive parts. At the same time, the above-mentioned problem is solved by forming a slit also in the short-circuit end face between the short-circuit ends of the remaining adjacent through-hole conductive parts. In addition,
There may or may not be a conductive film on the inner surface of the slit on the short-circuit end surface side.

(Function) In the dielectric filter of the present invention, the coupling between the resonators becomes inductive coupling where slits are formed on the open end face of the dielectric block, and capacitive coupling occurs where slits are formed on the shorted end face. Therefore, inductive coupling and capacitive coupling are used in combination as a whole, and the attenuation characteristics on both the high and low frequency sides become steep, making it possible to realize a bandpass filter with well-symmetrical attenuation characteristics.

In addition, since there is no conductive film on the inner surface of the slit on the open end surface, it is convenient to finely adjust the degree of coupling between resonators by changing the depth of the slit in post-processing, and it can be easily formed with a rotating grindstone. It is easy to manufacture and can be manufactured at low cost.

(Example) Examples of the dielectric filter according to the present invention will be described below with reference to the drawings.

In FIGS. 1 to 3, dielectric block 1
A plurality of through conductive parts 2A to 2E are formed by forming a conductive film on the inner surface of the through hole, and the through conductive parts 2A to 2E are formed on the outer surface of the dielectric block (one surface and four sides where the through conductive parts are present). A conductive film 3 connected to 2E is formed of metallization such as silver.

Further, the open end surface 5 of the dielectric block 1 on which the open ends of the through conductive portions 2A to 2E are located is a portion on which no conductive film is formed. Then, the intermediate position of the through conductive parts 2A, 2B and the through conductive parts 2D, 2
EThe open end surface at the intermediate position has a slit 6 for connecting between stages.
are formed respectively.

On the other hand, on the short-circuited end surface of the dielectric block 1 where the short-circuited end where each of the through-hole conductive parts 2A to 2E is connected to the conductive film 3 is located, there are an intermediate position between the through-hole conductive parts 2B and 2C and an intermediate position between the through-hole conductive parts 2C and 2D. An inter-stage coupling strip 7 is formed in each of the stages.

Although a case is shown in which no conductive film is formed on the inner surfaces of the slits 6 and 7, a conductive film connected to the conductive film 3 may be formed on the inner surface of the slit 7 on the short-circuited end surface side.

According to the configuration of the above embodiment, by forming the interstage coupling slit 6 and the open end face of the dielectric block 1, the resonator portion by the through conductive portion 2A and the two
The resonator portion formed by B, the resonator portion formed by the through conductive portion 2D, and the resonator portion formed by 2E are each inductively coupled, thereby increasing the amount of attenuation on the high frequency side and making the attenuation characteristic steeper. Furthermore, by forming the interstage coupling slit 7 on the short-circuited end face of the dielectric block 1, a resonator portion formed by the through conductive portion 2B, a resonator portion formed by 2C, a resonator portion formed by the through conductive portion 2C, and a resonator portion formed by 2D are formed. By capacitively coupling these parts, the amount of attenuation on the low frequency side can be increased and the attenuation characteristics can be made steep. As a result,
A bandpass filter with good symmetry of attenuation characteristics can be realized.

Furthermore, since there is no need for a conductive film on the inner surface of the slit, it is possible to increase the depth of the slit using a rotary grindstone after metallizing the dielectric block to adjust the degree of coupling and, by extension, the filter characteristics on the high and low frequency sides. It is possible.

In the above embodiment, the slits 6 and 7 have a rectangular cross section, but the slits may have a substantially U-shaped cross section. Such a cross-sectional shape of the slit is convenient when forming the slit with a rotating grindstone.

In each of the embodiments described above, drawing out the input/output terminals is omitted, but it is possible to draw out the input/output terminals by, for example, coupling to the open end of the through-hole conductive portion by means of capacitance.

(Effects of the invention) As explained above, according to the dielectric filter of the invention, when a plurality of through conductive parts are arranged in parallel at intervals on a dielectric block having a conductive film formed on the outer surface, Since slits are formed on both end faces of the dielectric block where the open ends and short-circuited ends of the conductive parts are located, inductive coupling and capacitive coupling can be used together for coupling between the resonators formed around each through-conducting part. It can be made into a shape. As a result, the amount of attenuation on the high-frequency side and the low-frequency side can be made large and steep, and the attenuation characteristics can be improved. Furthermore, it is possible to change the degree of bonding by adjusting the slit depth.

Furthermore, since there is no conductive film on the inner surface of the slit on the open end surface, there is an advantage that the degree of coupling between the resonators can be finely adjusted by post-processing the depth of the slit.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of a dielectric filter according to the present invention, FIG. 2 is a front sectional view thereof, and FIG. 3 is a bottom view thereof. 1...Dielectric block, 2A to 2E...Through conductive portion, 3...Conductive film, 6, 7...Slit.

Claims (1)

[Scope of utility model registration request] A conductive film is formed on the inner surface of a plurality of through holes 3
In a conductive filter, a dielectric film is formed on four sides of a dielectric block in which three or more through conductive parts are arranged side by side at intervals, and on a short-circuited end face on which one end of the through conductive part is located. A slit having no conductive film is formed on the open end surface between the open ends of at least one set of adjacent through-hole conductive parts among the through-hole conductive parts, and a slit having no conductive film is formed on the short-circuited end face between the short-circuited ends of the remaining adjacent through-hole conductive parts. A dielectric filter characterized in that a slit is also formed.