JPS6338301A - High frequency filter - Google Patents

Abstract

PURPOSE:To improve the characteristics of inserting loss, band width, etc., by providing specific 1st and 2nd tuning circuits and applying the approximate connection to an optional side of a resonance line to set a conductor on the upper surface of said connection part via an insulated material. CONSTITUTION:The approximately U-shaped resonance lines 1 are formed on a primary surface side of a dielectric substrate 9 and a 1st capacities 3 are connected to the cut parts 2 of the lines 1. Then the external connection terminals 4 are connected to each end of the parts 2 or lines 1 via a 2nd capacities 5 or connection lines for formation of the 1st and 2nd tuning circuits 11 and 12 respectively. Each optional side of the lines 1 are approximately connected with each other and a conductor 8 is provided on the upper surface of this connection part 6 via an insulated material 7. Thus it is possible to obtain a compact high frequency filter with a resonance line of lambda/4 length and then to improve the characteristics of inserting loss, band width, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to high frequency filters such as Ul (F) used in various electronic devices.

As the conventional technique No. 14 UHF band frequency) C router, ', If! Always, λ
・A rectangular resonant circuit and a λ/4 resonant circuit 1. The resonant circuit is two types, but in either case, a wavelength shortening capacitor is connected to one or both sides of the resonant line. Still another example is a helical coil in which a λ/2 length copper wire is wound around a bobbin.

Problems to be Solved by the Invention As described above, in all conventional examples, a length of λ/4 or more was required and miniaturization was not possible.

SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems and to provide a high frequency filter constituted by a resonant line having a length of λ/4 or less and whose band characteristics can be adjusted relatively easily.

Means for Solving the Problem In order to solve this problem, the present invention provides a substantially U-shaped resonant line on one main surface of a dielectric substrate and a first capacitor at a cut portion of the resonant line. A first tuned circuit is provided in which one end of the disconnected part or the resonant line and the external connection terminal are connected via a second capacitor or coupled line, and a second tuned circuit having the same configuration as the first tuned circuit is provided. A tuning circuit is provided, any one side of the substantially U-shaped resonant line is closely coupled, and a conductor is provided on the upper surface of this coupling portion via an insulator.

Effect With this configuration, a compact high-frequency filter can be obtained using a resonant line with a length of λ/4 or less, and a conductor is provided on the top surface of the coupling part of the approximately U-shaped resonant line via an insulator, reducing insertion loss. In addition to being able to change the characteristics of band ``1'', etc., by changing its position and size, the above characteristics can be adjusted, and the yield of high-frequency filters that require high precision due to miniaturization can be improved. Improved equality 8-1. This is very advantageous in production.

Example The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a plan configuration diagram on a dielectric substrate of a high frequency filter according to an embodiment of the present invention configured with a substantially U-shaped resonant line;
The figure is a plan view of the main parts, FIG. 3 is a plan configuration diagram of another embodiment, and FIG. 4 is a characteristic diagram.

This high frequency filter has a first
As shown in the figure, a first capacitor 3 is connected to a cut section 2 of a substantially U-shaped resonant line 1, and a first capacitor 3 is connected to one end of the cut section 2 and an external connection terminal 4 via a second capacitor 6. A coupling portion 6 connects one tuned circuit 11 and a second tuned circuit 12 having the same configuration as the first tuned circuit 11 at a line portion on any one side of the resonant line 1.
A conductor 8 is provided on the upper surface of the coupling portion 6 with an insulator 7 interposed therebetween. Here, the insulator 7 and the conductor 8 may be integrated or may be constructed separately, and the position where they are provided and the sizes such as the length and thickness of l] can be arbitrarily set. FIG. 2 shows a side view of the main part of the previous embodiment, in which the tuning circuit 11.
12, and the other main surface, the lower surface, is used as a ground conductor 10 by leaving the copper foil as it is. Here, a microstrip line configuration using a double-sided copper-clad dielectric substrate is shown, but the tuning circuit 1 is provided on the main surface of the single-sided copper-clad dielectric substrate.
1.12 may be configured and bonded to a separately provided conductor, or a suspended line structure may be provided in which the line is attached to the conductor via a spacer.

6.-1 FIG. 3 is a plan view showing another embodiment, in which instead of connecting to the external connection terminal 4 using the second capacitor 5, a coupling close to a part of the resonant line 1 is used. Connection via the line 13 is also possible. Figure 4 shows an example of the improved characteristics obtained by the embodiment of the present invention, where B is the characteristic when the conductor 8 is provided at the joint part via the insulator 7, compared to the characteristic when the conductor 8 is not provided. As a result, insertion loss and band lJ simultaneous characteristics have been improved.

Effects of the Invention As described above, according to the present invention, insertion loss can be reduced by providing a conductor on the upper surface of the coupling portion via an insulator.

Characteristics such as band can be adjusted to the desired position.

By changing the size, the characteristics can be adjusted, and the yield of high-frequency filters that require high precision due to miniaturization can be improved, which is very advantageous in terms of design and manufacturing, and has great industrial effects.

[Brief explanation of the drawing]

Fig. 1 is a plan configuration diagram of a high frequency filter according to an embodiment of the present invention, Fig. 2 is a side view of the same main part, Fig. 3 is a plan configuration diagram of another embodiment, and Fig. 4 is a characteristic diagram. '-- Yes. 1... Resonant line, 2... Cutting section, 3.
...First capacity, 4...External connection terminal,
5...Second capacitor, 6...Coupling part, 7
...Insulator, 8...Conductor, 9...
...Dielectric substrate, 10...Ground conductor, 13...
...combined line. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 9 7ρ Figure 3? Figure 4/U Shouldagimaki GH2゜

Claims (1)

[Claims] A substantially U-shaped resonant line is provided on one main surface of the dielectric substrate, a first capacitor is connected to the cut part of this resonant line, and a second capacitor is connected to one end of the cut part or to the resonant line and the external connection terminal. Alternatively, a first tuned circuit connected via a coupling line is provided, and a second tuned circuit having the same configuration as the first tuned circuit is provided, and any one side of the substantially U-shaped resonant line is closely coupled. A high frequency filter is formed by providing a conductor on the top surface of this joint part with an insulator interposed therebetween.