JPH0756483Y2 - Dielectric filter - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dielectric filter such as a band elimination filter in which a coupled transmission line between resonators is made a lumped constant.

2. Description of the Related Art As the band elimination filter described above, one having a circuit configuration shown in FIG. 6 is known. In this filter circuit, an external Q adjustment capacitor 13 and a dielectric resonator 14 are connected in series at each end of the coil 11 between a transmission line 12 having a coil 11 and a ground, and a storage is provided. A capacitor 15 for capacitance is connected in parallel, and the coupling line is lumped with LC.

As shown in FIG. 7, such a filter assembling structure has a structure in which a plurality of resonators 14 are housed in a case 20 with the inner conductor 14a being horizontal and soldered to the inner conductor 14a and exposed to the outside. With respect to the terminal 16, the tip side bent portion 17a of the earth plate 17 having the base end portion sandwiched between the inner bottom surface of the case 20 and the outer conductor 14b of the resonator 14 is horizontally opposed to each other, and the opposing coupling terminals are opposed to each other. 16
Capacitors 13 and 15 are attached between the bent portion 17a and the bent portion 17a by soldering 18 or the like while floating in the air. Further, the resonator 14 is connected to the base end side of the ground plate 17 formed in a wave shape and the resonator.
It is pinched and supported by a spring 19 which is interposed between the upper case 14 and the case 20. 12 in the figure is the capacitor 13 and
It is a transmission line inserted between 15 and the cross section appears.

Problems to be Solved by the Invention However, because of such a configuration, there are the following drawbacks.

Since it is necessary to mount the capacitor in a state of floating in the air, even if the spring property of the earth plate 17 is used, the capacitor is clamped and supported between the coupling terminal 16 and the bent portion 17a,
Even if soldering or the like is performed, the mounting work is unstable, the assembling cannot be performed easily, and it is not suitable for mass production.

Since the distance between the capacitor mounting portion A and the case connecting portion B on the ground plate 17 is long, an extra inductance is generated here and the electrical characteristics are unstable.

Since the capacitor is suspended in the air, the mechanical strength is weak,
There is a problem that a mounting portion such as solder is peeled off by vibration or the like.

The present invention has been made to solve the above problems, and provides a dielectric filter which is easy to mount, can suppress the generation of an extra inductance component, and has a high mechanical strength. The purpose is to

Means for Solving the Problems In a dielectric filter according to the present invention, a dielectric resonator is housed in a case with its inner conductor horizontal, and a coupling terminal piece having a proximal end attached to the inner conductor. The tip portion is formed so as to project from the resonator in the horizontal direction, and the storage capacitor element and the external coupling element that are connected in series with the transmission line interposed between the tip portion and the ground potential portion that vertically opposes are provided. It is characterized by being

As the ground potential portion, even if it is the bottom surface inside the ground,
Alternatively, it may be a ground plate sandwiched between the dielectric resonator and the bottom surface inside the case.

Function In the present invention, the tip of the coupling terminal piece and the ground potential portion are opposed to each other in the vertical direction, and the stray capacitance element and the external coupling element are provided between them in the vertical direction. , Can be fixed with the upper element placed thereon.

Embodiment FIG. 1 is a sectional view showing a band elimination filter to which the present invention is applied, and FIG. 2 is a perspective view showing the main part thereof. The same parts as in FIGS. There is. This filter is the same as the circuit shown in FIG.
A prism-shaped dielectric resonator 14, for example, is housed in 20 with the inner conductor 14a being horizontal.

A ground potential portion, for example, a base end portion 7b of the ground plate 7 is inserted between the outer conductor 14b of the resonator 14 and the inner bottom surface of the case 20. The base end portion 7b is formed in a wavy shape, and the tip end portion 7a projecting from the resonator 1 is formed straight and is horizontally oriented along the inner bottom surface of the case 20. It is preferable that the tip portion 7a is provided so as to come into contact with the inner bottom surface of the case 20 so as not to shake due to vibration.

The inner conductor 14a of the resonator 14 is formed in a cylindrical shape, and a coupling terminal 6 made of a conductive material and having a cylindrical base end portion 6b is attached inside the resonator 14 by inserting the base end portion 6b. The tip portion 6a of the coupling terminal 6 is formed so as to face the tip portion 7a of the ground plate 7.

Between the top end 6a of the coupling terminal 6 and the top end 7a of the grounding plate 7 which are vertically opposed to each other, a disk-shaped storage capacitor 15 and an external Q adjustment capacitor (external coupling element) are disk-shaped from the bottom side. 13 are provided, and further, these two capacitors 15
A transmission line 12 having a coil 11 is sandwiched between and. In this portion, the capacitor for capacitor 15 is soldered on the tip portion 7a of the ground plate 7 and the coil is placed on this.
After the external Q adjustment capacitor 13 is soldered 18 with the transmission line 12 having 11 interposed therebetween, the inner conductor 14 is placed on the capacitor 13.
It is formed by attaching the solder 18 to the tip portion 6a of the coupling terminal 6 extending from b. The soldering may be performed separately as described above, but may be performed at once by reflow soldering such as VPS.

The attachment of the coupling terminal 6 to the inner conductor 14a is performed by the tip 6
a may be oriented in any direction in the circumferential direction of the inner conductor 14a, and may be determined according to the total height of the capacitors 15 and 13 for the storage capacitance and the external Q adjustment. For example, as shown in FIG. 3, the coupling terminal 6 may be attached so that the tip 6a is located on the lower side.

Since this coupling terminal can be attached only by fitting it in the inner conductor of the resonator, the use of this has an advantage that the work is simpler than the conventional soldering of the coupling terminal.

Although the earth plate 7 is used as the earth potential portion in the above embodiment, the present invention is not limited to this, and the structure shown in FIG. That is, on the inner bottom surface of the case 20, the capacitor 15
And a capacitor 13 for external Q adjustment are provided, the tip 6a of the coupling terminal 6 attached to the inner conductor 14a of the dielectric resonator 14 is connected to the upper external Q adjustment capacitor 13, and the case 20 is grounded. It may be configured. That is, the case 20 may be used as the ground potential section.

Further, the storage capacitor 15 and the external Q adjusting capacitor 13 do not use the disk-shaped capacitors as described above,
You may use what has a square plate shape.

FIG. 4 is a perspective view showing another embodiment of the present invention. In this filter, an external Q adjusting coil (external coupling element) 13 ′ is attached instead of the external Q adjusting capacitor 13. When this coil 13 'is used, even if the pass band of the filter is lower than the attenuation band, there is no disadvantage in terms of electrical characteristics.

It should be noted that although the prism resonator is used as the dielectric resonator 14 in the above-described embodiment, the present invention is not limited to this, and a cylindrical resonator or the like may be used.

Further, the terms “horizontal” and “upper and lower” in the present invention are not absolute ones but represent relative positional relations in a certain aspect to facilitate understanding.

Effects of the Invention As described in detail above, in the case of the present invention, since the tip of the coupling terminal piece and the ground potential portion face each other in the vertical direction, and the stray capacitance element and the external coupling element are provided in the vertical direction between them, After the element on the side is fixed, the element on the upper side can be fixed in a state where the element on the upper side is placed thereon, so that the soldering work and the assembly can be facilitated and mass production can be achieved.

Further, not only when the ground potential portion is the case but also when it is the ground plate, the distance between the ground potential portion and the case is short, so that the generation of extra inductance can be suppressed and the electrical characteristics can be stabilized. Furthermore, even if the ground potential part is a ground plate, it is in contact with the case, so the mechanical strength is improved, it is resistant to vibration, and peeling at the mounting part such as solder is prevented. it can.

[Brief description of drawings]

FIG. 1 is a sectional view showing a band elimination filter to which the present invention is applied, FIG. 2 is a perspective view showing an essential part thereof, FIG. 3 is a sectional view showing an example of mounting a coupling terminal, FIGS. FIG. 6 is a sectional view and a perspective view showing another embodiment of the present invention.
FIG. 7 is an equivalent circuit diagram of the band elimination filter, and FIG. 7 is a sectional view showing the structure of the conventional band elimination filter. 6 ... Coupling terminal, 6a ... Tip part, 6b ... Base end part, 7 ... Ground plate, 7a ... Tip part, 7b ... Base end part, 12 ... Transmission line, 13 ... External Q adjustment capacitor, 13 '... External Q Adjustment coil, 14
… Dielectric resonator, 14a… Inner conductor, 14b… Outer conductor, 15… Stray capacitance capacitor, 20… Case.

Claims (3)

[Scope of utility model registration request] 1. A dielectric resonator is housed in a case with its inner conductor being horizontal, and the tip of a coupling terminal piece attached to the inner conductor at the base end side projects horizontally from the resonator. A dielectric filter characterized in that a storage capacitance element and an external coupling element which are formed and are connected in series with a transmission line interposed therebetween are provided between the tip portion and a ground potential portion which vertically opposes each other. 2. The dielectric filter according to claim 1, wherein the ground potential portion is a bottom surface inside the case. 3. The dielectric filter according to claim 1, wherein the ground potential portion is a ground plate sandwiched between the dielectric resonator and the bottom surface inside the case.