JPH04287501A - Dielectric filter and its adjustment method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a dielectric filter, in particular,
The present invention relates to a waveguide-type TE101 mode dielectric filter in which a waveguide is formed by applying conductor metallization or plating to almost the entire surface of a dielectric block having a rectangular cross section, and a method for adjusting the same. This type of dielectric filter is expected to be a filter with low insertion loss in ultra-high frequency bands, but it is desired that it have a structure that is easy to adjust.

0002

2. Description of the Related Art FIG. 4 is a perspective view showing a conventional TE101 mode dielectric filter. By applying conductive metallization 12 over almost the entire surface of the rectangular parallelepiped dielectric block 10, a waveguide filled with dielectric material is formed inside. If the internal wavelength of the electromagnetic wave of the desired frequency is λg, one to three through holes are provided perpendicularly to the H plane at intervals of approximately λg /2, and the entire inner wall of the holes is also coated with conductive metallization. Conductor post 1 connected to H side
4, a TE101 mode dielectric filter is formed which selectively passes only electromagnetic waves of a desired frequency. 1
6 is a conductor for input/output coupling.

FIG. 5 is a diagram showing a method of adjusting the passband width by adjusting the coupling amount of the dielectric filter shown in FIG. Column (a) is a perspective view showing the dielectric filter of FIG. 4 cut along a plane perpendicular to the axis and passing through the conductor posts 14. If adjustment is necessary, make an adjustment hole 17 between the conductor posts 14 as shown in column (b), insert a metal rod 18 into it as shown in column (c), Connect by soldering to the H side as shown in column d). If the desired characteristics are not obtained, melt the solder again and attach the metal rod 18.
I changed the insertion depth and soldered again.

0004

The first problem with the above-described method is that it is necessary to form the hole 17 by cutting the dielectric material, which is difficult to process. Second, the characteristics will be unstable unless the metal rod 18 and the H surface are reliably soldered, so each time the position of the metal rod 18 is changed, 12, which is very complicated. Also,
During repeated soldering, the metallized part melts into the solder, causing so-called solder cracks, which causes the metallized part to chip, and as the area becomes larger, the filter insertion loss increases. .

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a TE101 mode dielectric filter and a method for adjusting the same, which allows the amount of coupling to be easily adjusted.

[0006]

[Means for Solving the Problems] A dielectric filter of the present invention that achieves the above-mentioned object includes a dielectric block having a predetermined rectangular cross section, and a conductive coating covering almost the entire circumferential surface of the dielectric block. and conductor posts provided so as to penetrate the dielectric block at predetermined intervals in the axial direction of the dielectric block and reach the conductor coatings on both opposing surfaces, the conductor posts are provided at predetermined intervals as many as necessary for adjustment.

Further, the method for adjusting a dielectric filter of the present invention is characterized in that a required number of the conductor posts among the conductor posts are disconnected from the conductor coating on one surface.

[0008]

[Function] Conventionally, the number of conductor posts placed at predetermined intervals was 1 to 3, but even if this number is increased, each conductor post can be made thinner to keep the overall susceptance value the same. , equivalent characteristics can be obtained. Also, by doing so, the value of susceptance handled by each conductor post becomes small, and each conductor post contributes as a circuit for fine adjustment.

According to experiments described below, when a conductor post is connected to both H-planes, it acts as an inductive susceptance, and when the connection with one H-plane is cut, it becomes a capacitive susceptance. It was revealed that it acts as In a hollow waveguide, such a conductor post can act as a resonator and a rejection circuit if its length is λ/4, but in a dielectric-filled waveguide, it No such resonance characteristics were observed. The reason for this is not clear at present, but it is clear that it is due to the difference in dielectric constant within the waveguide.

[0010] Therefore, by separating the conduction between the conductor post and one H-plane while looking at the characteristics, a part of the conductor post changes from contributing as an inductive susceptance to contributing as a capacitive susceptance. By changing the overall susceptance, the amount of coupling, that is, the passband width can be adjusted.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing a dielectric filter according to an embodiment of the present invention. Components that are the same as those in FIG. 4 are given the same reference numbers and their explanations will be omitted. In the conventional TE101 mode dielectric filter (FIG. 4), one to three conductor posts 14 are provided approximately every λg /2, but in the example of FIG. provided.

FIG. 2 is an enlarged cross-sectional perspective view for explaining the details of the conductor post 15, and column (a) shows the conductor post before adjustment and is electrically connected to the two H planes; Column b) shows that the conductor coating of the connection portion 20 between the conductor post and the upper H surface is removed together with the dielectric block for adjustment. Next, experimental results regarding the difference in susceptance between a conductor post that conducts to two H planes as shown in column (a) of FIG. 2 and a conductor post that conducts to only one H plane as shown in column (b) of FIG. 2 will be explained. As shown in FIG. 3, it is filled with dielectric material with εr =4.5 and φd =0.
Table 1 shows the measurement results of the normalized susceptance B for waveguides of the dimensions shown having conductor posts of two different diameters: 8 mm and φd = 1.25 mm.

Table 1 Post diameter φd [mm]
Double-sided connection Single-sided connection
0.8
-6.2 0.6
1.25
-9.8
1.0 According to the experimental results shown in Table 1, by cutting off the connection with one side, the inductive property changes to the capacitive property, and the absolute value becomes about 1/10. Therefore, by disconnecting some of the many conductor posts from one surface, the overall susceptance value can be adjusted.

[0014] If the post diameter is as designed, there is no need to make any special adjustments to the filter, but in actuality, the tolerance of the post diameter, the length in the H-plane (long side) direction, variations in dielectric constant, etc. The susceptance value fluctuates. Since this adjustment reduces the susceptance value, it is designed with a slightly increased susceptance value (that is, a filter with a narrow bandwidth with a small amount of coupling). After that, the necessary posts are shaved off as shown in Figure 2(b) to gradually increase the amount of bonding. At this time, the more the post stands in the center, the more the susceptance changes, and the closer it gets to the E plane, the smaller the change. In other words, if you want to change the amount of coupling by a large amount, you only need to remove the post near the center, and when the characteristics have been incorporated, you can remove the posts on both sides when making final fine adjustments.

[0015]

[Effects of the Invention] As described above, according to the present invention,
A TE101 mode dielectric filter and its adjustment method are provided that allow easy adjustment of the amount of coupling, that is, the passband width.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention.

FIG. 2 is an enlarged perspective cross-sectional view of a portion of the filter in FIG. 1;

FIG. 3 is a perspective view for explaining susceptance measurement conditions.

FIG. 4 is a perspective view of a conventional TE101 mode dielectric filter.

FIG. 5 is a perspective cross-sectional view for explaining a method of adjusting the amount of coupling of a conventional dielectric filter.

[Explanation of symbols]

10...Dielectric block 12...Conductor coating 14, 15...Conductor post 16...Input/output coupling conductor

Claims (2)

[Claims] 1. A dielectric block (10) having a predetermined rectangular cross section, a conductive coating (12) covering almost the entire circumferential surface of the dielectric block, and a conductive film (12) disposed in the axial direction of the dielectric block (10). and conductor posts (15) provided so as to penetrate the dielectric block (10) at predetermined intervals and reach the conductor coatings (12) on opposite surfaces of the dielectric filter. (15) A dielectric filter characterized in that the number of filters required for adjustment is provided at predetermined intervals. 2. The method for adjusting a dielectric filter according to claim 1, characterized in that a required number of conductor posts among the conductor posts (15) are disconnected from the conductor coating on one surface. How to adjust a dielectric filter.