JPS60140901A - Helical filter - Google Patents

Abstract

PURPOSE:To attain stable characteristic by metallizing the inner circumferential face of a cylindrical dielectric, metallizing a conductor equivalent to a helical coil to the outer circumferential face in spiral and constituting the titled filter with a 1/4 wavelength resonator where one terminal is short-circuited and the other terminal is opened so as to allow the filter withstand the vibration. CONSTITUTION:The inner circumferential face of the cylindrical dielectric 10 is metallized and the helical coil 11 is metallized in spiral to the outer circumferential face, the end face close to an input/output terminal 12 is short circuited and the other end is opened. The input/output terminal 12 is matched by changing the position of a matching point B. Furthermore, the resonance frequency is made variable by a tuning screw 13 fitted to a case. Moreover, the inter-stage coupling is performed by a window 14. Since the dielectric is used for the resonator in this way, the resonator withstands the vibration and low loss is attained and also the use of the dielectric allows the resonator to decrease the line and attain miniaturization with a dielectric constant in response to the employed dielectric.

Description

DETAILED DESCRIPTION OF THE INVENTION The industrial field of application relates to helical filters used in radio communication devices and the like in high frequency bands (VHF-UHF bands).

Conventional Structure and Problems Conventionally, a helical filter has been used as a bandpass filter in the pVHF band and UHF band. This filter is shown in FIGS. 1(a) and (1), respectively. These are two-stage helical filters.

In the filter shown in FIG. 1(a), a resonator is formed by a helical coil 1 and a trimmer capacitor 2, and input and output are matched by changing the position of a matching point, and connected to an input/output connector 3. Furthermore, the degree of coupling can be adjusted by three pages depending on the opening area of the coupling window 4 provided between the resonators.

However, the above configuration has problems such as the helical coil 1 having an air core and being susceptible to vibrations, and that it is difficult to make the intervals of L uniform.

On the other hand, in the case of the filter shown in FIG. 1(b)K, a helical coil 1 is wound around a coil bobbin 5, and the resonance frequency is adjusted by a ferrite core 6. has.

According to the above configuration, the helical coil 1 has a coil bobbin 6
Although vibration is improved since the ferrite core 6 is wound around the ferrite core 6, it is important to fix the ferrite core 6. Further, in this configuration, since the coil bobbin 5 is used, the no-load Q decreases. This method has the problem of increasing trench passage loss.

Purpose of the Invention The purpose of the invention is to provide a helical filter that is resistant to vibration, which is a problem with conventional helical filters, and has low loss. The overall purpose is to realize a helical filter with

The structure of the invention is to metallize the inner peripheral surface of a cylindrical dielectric body and metallize a conductor equivalent to a helical coil on the outer peripheral surface in a spiral shape, or metallize the entire outer peripheral surface and then conductor in a linear shape. The helical filter is made up of a wavelength resonator with one end short-circuited and the other end open, making it resistant to vibration, and the helical coil is metallized on top of the dielectric material to reduce loss. .

DESCRIPTION OF EMBODIMENTS An embodiment of the invention will be described below with reference to the drawings.

FIG. 2 shows a side cross section of a helical filter in an embodiment of the invention.

In FIG. 2, reference numeral 10 is a cylindrical dielectric body, the inner circumference of which is metallized, and the outer circumferential surface of which is metallized with a spiral helical coil 11. , is short-circuited to the inner circumference, and the other end is open. Reference numeral 12 is a 5-page output terminal, and the position of matching point B is changed to ensure perfect matching. Further, the resonance frequency can be varied by a tuning screw 13 attached to the housing. In addition, the connection between the stages is window 1.
This is done by 4.

Figures 3 and 4 are the second example of the uninvented. This figure shows a single resonator as a main part of a helical filter in a third embodiment.

In the resonator shown in FIG. 3, the open end has the entire outer peripheral surface conductor extended to serve as one electrode of the capacitance with the tuning screw. On the other hand, in the resonator shown in FIG. 4, except for a part of the open end of the inner circumferential surface and the outer circumferential surface, all other surfaces are metalized, and the conductor gold wire on the outer circumferential surface is removed to form the helical coil 11. This is what I did.

As is clear from the above three embodiments, a conductor is metallized on the inner peripheral surface of the cylindrical dielectric 1o, while a conductor equivalent to the helical coil 11 is metalized in a spiral shape on the outer peripheral surface, or a conductor is metalized on the outer peripheral surface. The entire surface is metallized and the conductor is removed in a linear manner.One end is short-circuited and the other end is open, which uses a wavelength resonator.As shown in page 6, it is strong against vibrations and has low loss characteristics. It can also be stabilized.

In the above embodiment, a two-stage resonator is described, but it is of course applicable to a multi-stage resonator, and the shape of the resonator is not limited to a cylindrical shape, but can also be realized in a prismatic shape, etc. The shape of the resonator is not limited to this.

As explained in detail, the invention improves the problems of conventional helical filters, and by using a dielectric material in the resonator, it is strong against vibration and has low loss. Use all dielectric materials.

Therefore, the line can be shortened with a dielectric constant depending on the dielectric material used, and the size can be reduced. In addition, since the helical coil is metallized on top of the dielectric material, the line spacing and line width can be made uniform, making it possible to create a helical filter with less variation in characteristics, which is excellent in mass production and has great effects. There is.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are 7-page side sectional views of a conventional helical filter, Figure 2 is a side sectional view of a helical filter according to an embodiment of the non-invention, and Figures 3 and 4 are non-inventive side sectional views. Second invention. FIG. 7 is a perspective view of a single resonator of a main part of a helical filter in a third embodiment. 10 ``゛''' dielectric, 11 ゛°°゛°゛ helical coil, 12... Input/output terminal, 13...
Tuning screw, 14... Combined window. Name of agent: Patent attorney Toshio Nakao and 1 other artist
1 figure

Claims (4)

[Claims] (1) A conductor is metallized on the inner peripheral surface of the dielectric, and a helical coil is formed on the outer peripheral surface.One end of the metallized conductor is short-circuited, and the other end is open, which is a helical filter that is fully equipped with a wavelength resonator. . (2) '/ The helical filter according to claim 1, wherein the open end of the wavelength resonator is formed such that a tuning screw for adjusting the resonance frequency faces the open end. (3) Claim 1, characterized in that the metallization of the outer peripheral surface of the dielectric in the '/4 wavelength resonator is such that a helical coil is formed by metallizing the conductor in a spiral shape. Helical filter as described. (4) '/ The metallization on the outer circumferential surface of the dielectric in the wavelength resonator is characterized in that the metallization is uniform on the surface, and a helical coil is formed by removing the entire conductor in a linear manner after page 2. A helical filter according to claim 1.