JPH0374841B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for variably adjusting the reactance of a dielectric resonator used in a transmitter or receiver for high frequency bands such as microwaves.

As is well known, dielectric resonators for microwaves that use dielectric materials such as barium titanate have low loss, so-called high Q, and have a large dielectric constant, so they can be miniaturized. Widely used in microwave band mobile radio equipment, etc.
As a conventional technique related to this type of dielectric resonator, holes for coupling adjustment of holes for a plurality of resonators are alternately provided at predetermined intervals in a single rectangular parallelepiped dielectric block. By forming a metallized layer on the inner surface of the resonator hole and the outer surface (side and bottom surfaces) of the dielectric block, multiple resonant elements with a resonant wavelength four times the length of the resonator hole are formed, and There is a structure in which these are appropriately combined depending on the shape and position of the coupling adjustment hole. In this case, the input/output coupling part for coupling with the external circuit generally has a configuration in which metal input/output terminals are inserted into coupling holes formed at both ends of the dielectric block. The external circuit and the dielectric resonator are coupled through the dielectric resonator.

A conventional filter using such a dielectric resonator is adjusted so that its impedance is around 50Ω. Therefore, it is necessary to connect it to other transmission lines in which it is incorporated using the same 50Ω line. However, in reality, since there is a reactance component in the line, it is not always easy to connect this filter to other circuits, and it is difficult to match the input and output of the transistor amplifier.

Further, this type of dielectric resonator is also used as an antenna duplexer in a mobile radio system for simultaneous transmission and reception, in which the transmission frequency and reception frequency are different. In this case, the transmitting side coupling circuit and the receiving side coupling circuit are provided with a combining circuit such that when the transmitting filter and the receiving filter are viewed from the coupling point at the receiving frequency and the transmitting frequency, respectively, the respective impedances are in an almost open state. According to the prior art, this composite circuit uses a coaxial cable whose length is precisely adjusted, but in reality it is quite long and requires a large space. Therefore, it is a fact that there is a strong desire for another system that can easily perform phase synthesis of such a duplexer in a small size.

It is an object of the present invention to easily adjust the reactance of a dielectric resonator, thereby making it easy to couple with other circuits or transistor amplifiers, and to synthesize the phase of a duplexer. The aim is to provide a new method that can be used for both practical and commercial purposes.

The present invention, which was devised to achieve such an object, is a dielectric resonator with an integral structure, in which a metal rod or dielectric rod is inserted into the input/output coupling hole from the direction opposite to the input/output terminal. The structure is such that the reactance can be varied accordingly.

Hereinafter, the present invention will be explained in more detail based on the drawings. FIG. 1 is an explanatory diagram showing an embodiment of the reactance adjustment method according to the present invention. The dielectric block 1 used in this embodiment is a sintered, almost rectangular parallelepiped block made of a material with a high dielectric constant, such as barium titanate, and has three dielectric blocks spaced apart in the longitudinal direction. Hole 2 for resonator
and a hole 3 for coupling adjustment provided between them. Input/output coupling holes 4 are provided at both ends of such a dielectric block 1, respectively. A metallized layer is formed on the outer surface of the dielectric block 1 except for its top surface (ie, the side surfaces and bottom surface) and on the inner surface of the resonator hole 2. This metallized layer is a very thin metal layer, and is formed by, for example, applying a silver paste or the like and baking it. Then, a metal input/output terminal 5 is inserted into the input/output coupling hole 4 to form a dielectric resonator.

The configuration up to this point is completely the same as the conventionally known configuration. Here, the present invention is significantly different from the prior art in that the reactance adjustment rod 6 is inserted into the input/output coupling hole 4 from the direction opposite to that of the input/output terminal 5. This reactance adjustment rod 6 is a rod made of a metal material or a dielectric material, and one of them is selected depending on whether to increase the inductive component or the capacitive component. Become. That is, if it is desired to increase the inductive reactance, a metal rod may be selected as the reactance adjustment rod 6 and inserted into the input/output coupling hole 4. Conversely, if it is desired to increase the capacitive reactance, a dielectric rod may be selected as the reactance adjustment rod 6 and inserted into the input/output coupling hole 4.

FIG. 2 shows how the impedance of the dielectric resonator changes depending on the material of the reactance adjustment rod 6 and the amount of insertion into the input/output coupling hole 4. For example, as is clear from the Smith chart (Z chart) in Figure 2, by increasing the insertion amount of the metal rod (usually by several mm)
The impedance of the dielectric resonator moves in the inductive direction and can be freely adjusted to the desired value. The same thing happens with the dielectric rod, and as the amount of insertion increases, the impedance of the dielectric resonator moves toward capacitance. Note that these reactance adjustment rods are preferably inserted into the input side coupling holes.
This is because the phase appears to change more greatly when inserted into the input side coupling hole.

Since the present invention is a reactance adjustment method of a dielectric resonator configured as described above, for example, the impedance is adjusted to be around 50Ω as a normal filter, and when canceling the reactance of the line in which it is installed, it should be canceled. By selecting a metal rod or dielectric rod depending on whether the reactance is capacitive or inductive, and adjusting the insertion amount appropriately, the reactance of the line can be easily canceled out. Because it operates effectively, it can be easily coupled with other circuits, it can be easily matched to the input and output of transistor amplifiers, and it can also be used for phase synthesis of duplexers. It can have many excellent effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the method for adjusting the reactance of a dielectric resonator according to the present invention, and FIG. 2 is a Smith chart for explaining the operation thereof. 1... Dielectric block, 2... Hole for resonator,
3... Hole for coupling adjustment, 4... Hole for input/output coupling, 5... Input/output terminal, 6... Reactance adjustment rod.

Claims (1)

[Claims] 1. In a dielectric resonator with an integral structure in which a plurality of resonator holes are provided in the longitudinal direction of a rectangular parallelepiped dielectric block, a metal rod or A method for adjusting the reactance of a dielectric resonator, characterized in that the reactance is varied by inserting a dielectric rod.