JPH03292001A - dielectric filter - Google Patents

Abstract

PURPOSE:To prevent the deterioration in Q and to evade the decrease in the level of a frequency characteristic by arranging dielectric coaxial resonators in parallel whose height is nearly equal to each other on a substrate and providing slots with different depth coaxially to the circumference of a through hole to each of the dielectric coaxial resonators. CONSTITUTION:Each of dielectric coaxial resonators 8, 9, 10 is formed to be a square pole having a throughhole A, and a ring slot B is formed coaxially with the throughhole A. Moreover, the depth of the slot B of the dielectric coaxial resonator 9 is formed deeper than the slot B of the dielectric coaxial resonators 8, 10. Moreover, the slot B is tapered wider at the opening and narrower toward the bottom, and the bottom of the slot B is formed as a curved face. Wall faces of the dielectric coaxial resonators 8, 9, 10 are pressed into contact and soldered and the dielectric coaxial resonators 8, 9, 10 are connected in parallel electrically by the capacitor formed on the base 1 in this state. The length of each resonator is selected almost constant but the depth of the slot of the dielectric coaxial resonators 8, 9, 10 differs from each other, then the resonance frequency of each dielectric coaxial resonators 8, 9, 10 is set high and low.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a dielectric filter used in automobile telephones and the like.

2. Description of the Related Art In a conventional dielectric filter, for example, three dielectric coaxial resonators 2.degree. 3.4 are arranged side by side on a substrate 1 as shown in FIG. In this case, the dielectric coaxial resonators 2 and 4 have high resonant frequencies, and the dielectric coaxial resonators 3
has a low resonant frequency.

In other words, as shown in Figure 3, if the length of the dielectric coaxial resonator is made longer, the inductance component will increase and the resonant frequency will be lower.If the length of the dielectric coaxial resonator is made shorter, the inductance component will be reduced and the resonant frequency will be higher. become. These three dielectric coaxial resonators 2, 3.4 are used to obtain filter characteristics in a predetermined band. Note that 5 in Figure 3 is a metal pin, and this bottle 5
Each of the dielectric coaxial resonators 2 to 4 is electrically and mechanically fixed on the substrate 1 via. Further, 6 and 7 are people and output terminals.

Problems to be Solved by the Invention However, the structure described above has a problem in that the overall characteristic level is low. That is, in order to obtain a dielectric coaxial resonator with a high resonant frequency, the length must be shortened, but when the length is shortened in this way, the Q characteristic inevitably becomes low. As a result, the overall level of filter characteristics becomes low.

Therefore, it is an object of the present invention to prevent the level of frequency characteristics from decreasing.

Means for Solving the Problems In order to achieve this object, the present invention arranges dielectric coaxial resonators with approximately equal heights side by side on a substrate, and each of these dielectric coaxial resonators has a In this example, a groove of increasing depth is provided coaxially around the periphery of the through hole.

If the configuration is more than just the function, the length of each dielectric coaxial resonator is almost constant, but the resonant frequency of each dielectric coaxial resonator can be increased by making the depth of the groove different. Can be set to a low value. Therefore, frequency characteristics are obtained by combining high and low frequencies,
In addition, the dielectric coaxial resonator with a high resonant frequency and the dielectric coaxial resonator with a low resonant frequency have the same height, so there is no drop in Q, and as a result, it is possible to prevent a drop in the level of frequency characteristics. be.

Example An embodiment of the present invention will be described below with reference to the accompanying drawings.

Note that in FIGS. 1 and 2, the same parts as in FIG. 3 of the conventional example are given the same numbers to simplify the explanation.

In Fig. 1, the dielectric coaxial resonator used this time 8.9.
10, as shown in FIG. 2, has a square prism outer shape with a through hole A, and an annular groove B is provided coaxially with the through hole A at the periphery of the through hole A on the upper surface. Note that the groove B of the dielectric coaxial resonator 9 is deeper than the groove B of the dielectric coaxial resonators 8 and 10. Although the groove B provided in each dielectric coaxial resonator 8 to 10 is not shown, the opening is wide and has a slope that becomes narrower toward the bottom, and the bottom of the groove B is as shown in Figure 2. It has a curved surface. These dielectric coaxial resonators 8, 9.10
The walls of the dielectric coaxial resonators 8.9.1 are brought into contact with each other and soldered as shown in Fig.
0 are electrically connected in parallel by capacitors formed on the substrate 1.

The substrate l used here has appropriate conductive patterns formed on both sides thereof, and an input terminal 6 and an output terminal 7 are soldered to both ends thereof. Furthermore, three bottles 5 are erected on the top surface of the substrate 1, and each bottle 5 is inserted into the through hole A of the dielectric coaxial resonator 8.9.10 and soldered in this state. .

In the above embodiment, the groove B has a circular annular shape, but it may be a rectangular annular shape, or it may not be annular.

Effects of the Invention As described above, in the present invention, by making the heights of the dielectric coaxial resonators almost the same, the dielectric coaxial resonators having a high resonant frequency can have a higher Q. In comparison, the overall Q can be increased. Further, by using a plurality of dielectric coaxial resonators provided with coaxial grooves, the third harmonic can be shifted to the high frequency side, and as a result, excellent filter characteristics are exhibited.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of the dielectric filter of the present invention;
FIG. 2(a) is a plan view of a dielectric coaxial resonator provided with coaxial grooves, FIG. 2(b) is a front view thereof, and FIG. 3 is a front view of a conventional dielectric filter. 1...Substrate, 8,9.10...Dielectric coaxial resonator, A...Through hole, B...Groove.

Claims (1)

[Claims] A substrate and a plurality of dielectric coaxial resonators mounted side by side on the substrate, the heights of the plurality of dielectric coaxial resonators are made approximately the same, and the plurality of dielectric coaxial resonators are A dielectric filter in which coaxial grooves with different depths are provided around the periphery of the through hole on the end face of the resonator.