JPH0247602Y2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) The present invention relates to a dielectric filter using dielectric resonators, particularly for coupling between each dielectric resonator and between a dielectric resonator and an input/output terminal. Concerning improvements in the structure of the capacitor part.

(Description of Prior Art) A dielectric filter, in which a plurality of dielectric resonators are arranged in parallel and the resonators are coupled by appropriate means, is small and widely used, especially in the microwave band.

FIG. 1 shows an example of a conventional dielectric filter, in which a plurality of dielectric resonators RN ₁ to RN ₄ are coupled using individual capacitors C ₁ to C ₅ . However, since multiple single capacitors are used, it is large and cumbersome to assemble.

FIG. 2 shows another example of a conventional dielectric filter. In this case, a plurality of electrodes EL ₁ to EL ₆ are formed on one surface of the insulating plate 1 by a thick film method, and a capacitance is formed between the edges of each electrode. The dielectric resonators RN ₁ to RN ₄ are connected to the electrodes EL ₂ to RN 4.
Connected to EL ₅ . However, each electrode EL ₁ to EL ₆
Since the capacitance cannot be increased unless the width X is large, the insulating plate 1 also becomes large. Furthermore, since an unequal electric field is generated between the electrodes, there is a large loss, and since the distance between the electrodes is shortened, the withstand voltage also tends to be low.

(Purpose of the invention) In view of the above points, the present invention consists of forming T-shaped electrodes consisting of a band-shaped coupling electrode part and a connecting tongue part extending from the middle of the coupling electrode part alternately on both sides of an insulating plate. The present invention aims to provide a dielectric filter that can be miniaturized, mass-produced, and have uniform characteristics by configuring a coupling capacitor between stages.

(Embodiments of the invention) Hereinafter, embodiments of the dielectric filter according to the invention will be described with reference to the drawings.

FIG. 3 is a front sectional view showing the overall configuration of the embodiment;
FIG. 4 is a perspective view of the same, and FIG. 5 is a plan view of a portion constituting an input/output and interstage coupling capacitor.
In these figures, both sides (front and back) of an insulating plate (dielectric plate) 2 are coated with silver, copper, etc., consisting of a band-shaped coupling electrode section 3 and a connecting tongue section 4 extending from the middle of the coupling electrode section. T-shaped electrodes ET ₁ to ET ₄ are alternately formed by a thick film method. The ends of the coupling electrode portions 3 of the T-shaped electrodes ET ₁ to ET ₄ face each other to form a capacitance. Furthermore, an input electrode Ein and an output electrode Eo are formed at the end of the insulating plate 2 by thick film technology, and the input electrode Ein faces one end of the coupling electrode part 3 of the T-shaped electrode ET ₁ , and the output electrode Ein faces one end of the coupling electrode part 3 of the T-shaped electrode ET 1. The electrodes Eo are opposed to one end of the coupling electrode portion 3 of the T-shaped electrode ET ₄ , and each form a capacitance. Then, each T-shaped electrode ET ₁ to
Dielectric resonators RN ₁ to 4 are connected to the connecting tongue 4 of ET ₄ .
RN ₄ is connected by soldering, brazing, etc. via a predetermined length of connection line. Here, the dielectric resonator
In RN ₁ to RN ₄ , electrodes 6 made of silver, copper, etc. are formed on the outer peripheral surface, inner peripheral surface, and lower end surface of a cylindrical dielectric 5, and the dielectric surface is exposed only on the upper end surface. λ:
wavelength) constitutes a resonator.

Note that the input electrode Ein and the output electrode Eo are connected, for example, to a center conductor of a coaxial connector 7 as an input/output terminal, and the ground side of the coaxial connector 7 is connected and fixed to a shield case 8.

(Effects of the invention) As explained above, according to the dielectric filter of the invention, a T-shaped electrode consisting of a band-shaped coupling electrode portion and a connecting tongue extending from the middle of the coupling electrode portion is attached to an insulating plate. Since the coupling capacitors between the stages are formed by forming the coupling capacitors alternately on both surfaces, it is not necessary to set the width of the coupling electrode portion of each T-shaped electrode to be large, and the insulating plate can be miniaturized. In addition, the dielectric resonator can be connected to the tip of the connecting tongue of the T-shaped electrode at the shortest distance, reducing the influence of inductance due to the connecting line, improving and stabilizing the characteristics, and making it possible to achieve static Since the connection line is connected to a point away from the end of the coupling electrode part that constitutes the capacitance, there is no capacitance shift when connecting. Further, by accurately forming the shape and position of each electrode using thick film technology or the like, trimming of the electrodes can be made unnecessary and products with uniform characteristics can be mass-produced. Furthermore, since the portions of each electrode that face each other via the insulating plate have a nearly uniform electric field, it is possible to reduce loss and increase the withstand voltage, thereby improving the characteristics as a filter.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one example of a conventional dielectric filter, FIG. 2 is a schematic configuration diagram showing another example of a conventional dielectric filter, and FIG. 3 is an implementation of the dielectric filter according to the present invention. FIG. 4 is a front sectional view showing an example, FIG. 4 is a perspective view thereof, and FIG. 5 is a plan view showing a portion constituting an input/output and interstage coupling capacitor. 1, 2... Insulating plate, 3... Coupling electrode section, 4...
Connection tongue piece, 5... Cylindrical dielectric, 6... Electrode, Ein... Input electrode, Eo... Output electrode,
ET ₁ to ET ₄ ...T-shaped electrode, RN ₁ to RN ₄ ...
dielectric resonator.

Claims (1)

[Scope of utility model registration request] T-shaped electrodes each consisting of a band-shaped coupling electrode portion and a connecting tongue extending from the middle of the coupling electrode portion are alternately formed on both sides of the insulating plate, the ends of the coupling electrode portions are opposed to each other, and the A dielectric filter characterized by having a configuration in which a dielectric resonator is connected to a connecting tongue portion.