JPH0137807B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to dielectric ceramics used in dielectric resonators and the like used in applied equipment in the microwave field, such as satellite receivers. In recent years, with the development of space communications and the like, the use of dielectric resonators in fields that utilize microwaves, such as receivers for satellites, is steadily increasing. The dielectric resonator used in the microwave field has a dielectric constant (ε) at a working frequency of 1 GHz or more.
It is desirable that the value is 30 to 40, which is suitable for 12 GHz, and the Q (Qu) at no load is 3700 or more, and the temperature coefficient (τ _fp ) of the resonant frequency is -25 < τ _fp < +25 (ppm/℃). ,
A small one is desirable, and when forming the circuit, the temperature coefficient of the resonance frequency is centered around 0,
It is desirable to be able to obtain a dielectric resonator by freely controlling the value. However, in conventional dielectric resonators, the temperature coefficient of the resonant frequency at 3 GHz is as large as +30 ppm/°C, and the variation is large, so it is necessary to freely control the temperature coefficient of the resonant frequency to provide a dielectric resonator. I had not yet reached that point. The purpose of the present invention is to solve the conventional problems and to reduce the temperature coefficient of the resonant frequency to −25<τ _fp <+25 (ppm/℃).
The object of the present invention is to provide a small dielectric resonator, and further to provide a dielectric ceramic whose temperature coefficient value can be freely controlled around 0. The feature of the present invention is that BaO−XTiO (3.9×4.1)
Dielectric ceramics were created by adding 1 to 26 wt% of ZnO to 100 wt% of the system composition. The present inventor has experimentally investigated various dielectric resonator materials in order to fabricate a resonator with excellent temperature change characteristics of the resonance _frequency . By using a material to which 1 to 26 wt% of ZnO is added, the dielectric constant (ε) can be increased from 30 to 30.
40, Q (Qu) at no load is more than 3700, and
Temperature coefficient of resonance frequency (τ _fp ) is −25 < τ _fp <+25
(ppm/°C), and also finely control the temperature coefficient value around 0 to create a dielectric resonator. The reason for limiting the amount of ZnO added is that if it is less than 1wt%, the temperature coefficient of resonance frequency (τ _fp ) will become too large on the positive side.
Moreover, if it exceeds 26 wt%, the temperature coefficient becomes too large on the negative side. The present invention will be explained below based on Examples. Example 1 Dielectric ceramics were created by using TiO ₂ and BaCO ₃ as BaO-XTiO ₂ raw materials, fixing X=4, and varying the amount of ZnO added. When creating, first,
Weigh the materials TiO ₂ , BaCO ₃ , and ZnO. Next, wet mixing is performed using a ball mill, etc., calcining is performed, and further,
After pulverizing and sizing the mixture, at a pressure of 500Kg/ ^cm2 ,
It was press-molded into a cylinder with a diameter of 30 mm and a thickness of 15 mm, and fired in a natural atmosphere at a temperature of 1200°C for 5 hours to obtain dielectric porcelain. Next, using the H ₀₁₁ mode of a microwave (3.0GHz to 3.5GHz) resonator obtained by sandwiching the dielectric ceramic between two opposing parallel metal plates, Q (Qu), temperature coefficient of resonant frequency (τ _fp ), and dielectric constant (ε) were measured, and the characteristics of each dielectric resonator were compared. The results are shown in Table 1.

【table】

[Table] As can be seen from Table 1, TiO ₂ is 61.8wt%,
When the amount of ZnO added to a mixture consisting of 38.2wt% BaCO ₃ is 11wt%, the temperature coefficient (τ _fp ) of the resonant frequency of the resulting dielectric resonator is 0 (ppm/℃), and the amount of addition is If it is less than 11wt%, it will gradually increase on the positive side, and if it is more than 11wt%, it will gradually increase on the negative side.
If the amount of ZnO added is less than 1wt%, the above temperature coefficient will be more than +25 (ppm/℃), and if it is more than 26wt%, -
25 (ppm/℃) or less. In addition, the dielectric constant of the dielectric resonator of Example 1 is 30 to 40, and the no-load Q (Qu) is also
It is over 3900. Example 2 Dielectric resonators were created using TiO ₂ and BaCO ₃ as BaO-XTiO ₂ raw materials, fixing the amount of ZnO added at 11 wt%, and setting X=3.9 and X=4.1. The method for manufacturing the dielectric resonator is the same as in Example 1. The results of this characteristic comparison are shown in Table 2.

[Table] As can be seen from Table 2, when X in BaO-XTiO ₂ is small, the dielectric constant (ε) of the resulting dielectric resonator becomes small, and when X is large, the unloaded Q (Qu)
tends to become smaller, and when X is smaller than 3.9,
When ε is less than 30 and greater than 4.1, Qu is 3700
This results in unfavorable characteristics as a resonator for microwaves (1.0 GHz to 12 GHz).

Claims (1)

[Claims] 1 Dielectric porcelain obtained by adding 1 to 26 wt% of ZnO to 100 wt% of a BaO-XTiO ₂ composition of 3.9×4.1, mixing and firing the mixture.