JPS61219210A - Low-pass filter - Google Patents

Abstract

PURPOSE:To obtain a small-sized low-pass filter, with which a damped quantity is obtained even in a high frequency band, by providing a hole or chipped section in the dielectric substrate of a multistage low-pass filter which uses a pattern formed of a metallic film on the dielectric substrate as a coil for reducing the floating coupling capacity between patterns. CONSTITUTION:A layer of air is provided at a part of a space where the floating coupling capacity is formed between printed coils by deleting a part of the space between the printed coils and the floating coupling capacity between the printed coils is reduced by cutting off a part of the electric fields concentrated onto a dielectric body. Namely, clearances 11 and 12 are those for reducing the floating coupling capacity among printed coils 6, 7, and 8. Therefore, the electrical separation between each printed coil is made larger and the floating coupling capacity between each printed coil is reduced and, as a result, a damped quantity is obtained even in a high frequency band.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a low-pass filter for suppressing harmonics of local oscillation of radio equipment and measuring equipment.

2. Description of the Related Art A conventional low-pass filter using a pattern formed of a metal film on a dielectric plate as a coil (hereinafter referred to as a printed coil) has printed coils 15 and 19 on the surface of a dielectric plate 17, as shown in FIG. 22, and a chip capacitor 14. By connecting the IJB to the ground via the full surface ground electrode 2 and the hair ground electrode 16, an equidistant circuit as shown in FIG. 3 was formed. Note 1
3 and 21 are input/output electrode sections.

FIG. 3 shows an equinodal circuit using lumped constants in the LC of a conventional low-pass filter. here.

23, 28, and 27 are coils, 24.26 is a grounding capacitor, and 28.29 is a stray coupling capacitance between each coil.

Further, FIG. 4 is a view of a conventional low-pass filter seen from the bottom, showing the state of formation of stray coupling capacitances 35.36 between printed coils 30.degree. and 31.32. In this way, since the electric field is concentrated in the dielectric substrate 37, the stray coupling capacitance 35, 36 becomes large, and the input and output are passed through the stray coupling, so it is difficult to desire a large amount of attenuation. Ta. Note that 33 is a chip capacitor and 34 is a ground electrode.

The problem that the invention seeks to solve In such a conventional low-pass filter configuration.

Because of the large stray coupling capacitance, we could not expect a large amount of attenuation in the high frequency range. In addition, in order to increase the amount of attenuation, it was necessary to increase the shape and reduce stray coupling capacitance.

The present invention has been made in view of this point.

The object of the present invention is to provide a small-sized, high-attenuation low-pass filter.

Means for Solving the Problems In order to solve the above problems, the present invention reduces stray coupling capacitance between patterns in a multi-stage low-pass filter that uses patterns formed of metal films on a dielectric substrate as coils. The dielectric substrate is characterized by having holes or chipped parts in order to reduce stray coupling capacitance and secure attenuation up to the high frequency range.

Effect of the present invention By removing a part between the printed coils,
By providing a layer of air in the part where the stray coupling capacitance between the printed coils is formed, the electric field concentrated in the dielectric material is partially cut off, thereby reducing the stray coupling capacitance between the printed coils. The aim is to secure attenuation up to a high frequency range without being greatly affected by stray coupling capacitance.

Embodiment FIG. 1 is a perspective view showing an embodiment of a low-pass filter according to the present invention.

In Figure 1, 1 is a dielectric substrate, 2.3 is a chip capacitor for grounding, 4.6 is a human output section electrode, 6, 7.8
9 is a printed coil electrode, 9 is a ground electrode, 10 is a whole surface ground electrode, and 11.12 is a gap for reducing stray coupling capacitance between printed coils 6, 7, and 8.

In the above configuration, the electrical separation between each printed coil is increased, the stray coupling capacitance is reduced, and an amount of attenuation can be obtained even in a high frequency range.

Effects of the Invention As described above, according to the present invention, it is possible to realize a low-pass filter that is small and has high attenuation even in a high frequency range, and is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a low-pass filter according to an embodiment of the present invention, FIG. 2 is a perspective view of a conventional low-pass filter,
FIG. 3 is a low-pass filter circuit using LC lumped constants, and FIG. 4 is a side view of the low-pass filter. 1...Dielectric substrate, 2.3...Chip connector/su, 6-8...Printed coil electrode,
11.12...Void area. Name of agent: Patent attorney Toshio Donakao and one other person f--
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Claims (1)

[Claims] A multi-stage low-pass filter using a pattern formed of a metal film on a dielectric plate as a coil, characterized in that a hole or a chipped part is provided in the dielectric substrate located at a part facing the pattern. low pass filter.