JPS6233362Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to improvements in dielectric resonators.

BACKGROUND ART Conventionally, in mobile radio systems, particularly in-vehicle radio systems, improvements have been made to systems and equipment in order to accommodate more users by effectively utilizing limited frequencies. However, in order to cope with the infinitely expanding demands, the VHF band gradually changed to the UHF band.
And the frequency is steadily increasing to the microwave band.

Furthermore, in mobile radio, the requirements for smaller size, lighter weight, and lower cost are fundamental. What is most desired in order to meet this requirement is a dielectric filter constructed of a semi-coaxial resonator using a ceramic dielectric material having a high dielectric constant and excellent temperature characteristics. For example, this filter has a dielectric constant of 40
When using a dielectric material of , the length can be reduced to 1/√40 compared to a normal one using air. Such a dielectric filter is shown in FIG. To briefly explain this, numeral 1 is a case, 2 is an antenna terminal, 3 is a hybrid, 4 is a semi-coaxial dielectric resonator, 5 is a transmission terminal, and 6 is a reception terminal. As shown in FIG. 2, the dielectric resonator 4 has a cylindrical dielectric 7 provided with a center conductor 8 and a metalized outer conductor 9, and a plurality of these are arranged inside a case 1 as shown in FIG. It is located in In the dielectric filter constructed in this way, by adjusting the resonant frequency of each semi-coaxial dielectric resonator 4 and coupling the resonators at appropriate intervals, filter characteristics as shown in FIG. 3 can be obtained. . In this case, the resonant frequency of the semi-coaxial dielectric resonator 4 has been conventionally adjusted by a method as shown in FIG. That is, a capacitance adding disk 10 is provided opposite the open surface 4a of the semi-coaxial dielectric resonator 4, and by moving this disk 10 up and down with a screw 11, the length of the resonator is equivalently varied to achieve resonance. Adjusting the frequency. However, with such an adjustment structure, it is not possible to adjust the resonator alone in advance. Furthermore, if the relative dielectric constant of the dielectric is 40, the length is 1/√40 of that of air, which requires high dimensional accuracy, making frequency adjustment difficult. Furthermore, due to its structure, it has poor temperature characteristics and vibration resistance. The present invention has been devised to improve these drawbacks.

Therefore, in the present invention, a plurality of coaxial and semi-coaxial resonators using a dielectric material are arranged in a row in a case, and two parts of the outer circumference of each resonator except for the part corresponding to the adjacent resonator are provided with an outer conductor. The dielectric filter is characterized in that a trimmable land made of a conductive film connected to the outer conductor is provided on a part of the open surface of the resonator.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 shows a top view of the embodiment, and FIG.
A sectional view taken along the - line in the figure is shown. To explain this embodiment with reference to the drawings, reference numeral 12 is a cylindrical dielectric material such as ceramic having a high dielectric constant, 13 is a center conductor provided inside the cylinder of the cylindrical dielectric material,
14 is an outer conductor metallized on the outer periphery and bottom surface of the cylindrical dielectric 12, and 15 is a land for frequency adjustment, which is the main point of the present invention. this land 1
5 is formed on the open surface of the dielectric 12 at the same time as the outer periphery and bottom surface of the dielectric 12 are metalized.
In this way, a coaxial resonator (the length of the dielectric is an integral multiple of the wavelength λ) and a semi-coaxial (the length of the dielectric is an integral multiple of 1/4 of the wavelength λ) is formed.

The dielectric resonator of the present invention formed in this manner has the following advantages. The first is that the resonant frequency can be adjusted by trimming the land 15 using a laser or mechanical method. Therefore, when configuring a dielectric filter, if the resonance frequency of each resonator is adjusted individually, the desired characteristics can be obtained when the resonators are housed in a case, and variations in the manufacturing process of the resonators can be absorbed. be able to.
Second, the resonator of the present invention has good vibration resistance because the resonant frequency adjustment land 15 formed on the open surface is in close contact with the dielectric 12. Thirdly, due to the same reason as the second, the temperature characteristics are good because there is no gap change due to the difference in temperature coefficient between the semi-coaxial resonator and the capacitance adding disk, unlike in conventional dielectric filters. be.

As explained above, the dielectric resonator of the present invention has improved temperature characteristics and vibration resistance by forming lands for adjusting the resonant frequency on its open surface, and can reduce costs due to easy adjustment. be.

[Brief explanation of the drawing]

Figure 1 is a top view of an example of a conventional dielectric filter, Figure 2 is a three-view diagram of a conventional dielectric resonator used in the dielectric filter, and Figure 3 is a characteristic curve diagram of a conventional dielectric filter. , FIG. 4 is a side sectional view of an example of a conventional dielectric filter, FIG. 5 is a top view of a dielectric resonator according to an embodiment of the present invention, and FIG.
It is a sectional view taken along the - line in the figure. 12... Dielectric, 13... Center conductor, 14...
Outer conductor, 15... Land for frequency adjustment.

Claims (1)

[Scope of utility model registration request] In a dielectric filter in which a plurality of coaxial and semi-coaxial resonators using a dielectric material are arranged in a row in a case, and an outer conductor is provided in two parts of the outer periphery of each resonator except for the part corresponding to the adjacent resonator. A dielectric resonator, characterized in that a trimmable land made of a conductive film connected to the outer conductor is provided on a part of the open surface of the resonator.