JPS6230405A - Branching filter - Google Patents

Abstract

PURPOSE:To check electromagnetic interference noise by forming a metal wall to which an RF power absorbing element is fitted in a branching filter consisting of plural filters to absorb electromagnetic leakage from respective filters which may be generated due to gaps. CONSTITUTION:The metal wall 6 to which the RF power absorbing element 7 is fitted is formed in the branching filter constituting of a metal case body 1 and plural filters consisting of resonance elements 3. In the part other than the peripheral part of a set screw 4, electromagnetic leakage from respective filters which may be generated due to the slight gaps 5 formed among the case body 1, the metal wall 6 and a metal plate 2 is absorbed by the absorbing element 7 to check the circular entering of the leaked electromagnetic waves into respective filters. Namely, the electromagnetic leakage from respective filters which may be generated due to the gaps 5 can be absorbed by the absorbing element 7 by forming the metal wall 6 to which the absorbing element 7 is fitted in the branching filter consisting of plural filters. Consequently, circular entering of the leaked electromagnetic waves into respective filters can be checked and electromagnetic interference noise generated in the gaps 5 can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a duplexer, and particularly to a duplexer having an RF power absorber in a metal wall between each filter.

[Conventional technology]

Conventionally, this type of duplexer has a metal plate 2 attached to a metal casing 1 housing a resonant element 3 and a metal wall 6 between each filter with setscrews 4, as shown in FIGS. 3 and 4. Often configured.

[Problem that the invention seeks to solve]

However, in such a configuration, the metal housing 1. The contact between the metal wall 6 and the metal plate 2 is made only around the set screw 4,
As shown in FIG. 4, the metal casing 1. A slight gap 5 is created between the metal wall 6 and the metal plate 2. Electromagnetic wave leakage occurs through this gap 5, and electromagnetic interference noise occurs between each filter, which has the disadvantage of interfering with the operation of the duplexer.

[Means for solving problems]

In order to eliminate such drawbacks, the present invention provides a duplexer having a plurality of filters provided with a metal wall to which an RF power absorber is attached.

[Effect]

In the present invention, leakage of electromagnetic waves between the filters caused by gaps is absorbed by the RF power absorber attached to the metal wall, thereby preventing electromagnetic waves from circulating between the filters. This makes it possible to prevent electromagnetic interference noise generated in the gaps between the filters.

〔Example〕

FIG. 1 is an external view showing an embodiment of a duplexer according to the present invention, and FIG. 2 is a cross-sectional view taken along line nn of FIG. 1. In FIGS. 1 and 2, 7 is an RF power absorber. 1st
FIG. 3 in FIG. 2.

The same or corresponding parts as in FIG. 4 are given the same reference numerals.

The duplexer having such a configuration is configured to reduce the electromagnetic wave leakage between the filters caused by the air gap 5 by using R attached to the metal wall 6.
By absorbing it by the F power absorber 7 and preventing the electromagnetic waves from circulating between the filters, it is possible to prevent electromagnetic interference noise between the filters.

The above describes a two-wave demultiplexer using an ink digital type filter, but the present invention is not limited to this. For example, the present invention is not limited to this. It is applicable to all known resonant elements and filter types such as body filters.

Furthermore, it goes without saying that the present invention can also be applied to the case of multiple wave demultiplexing of three or more waves.

〔Effect of the invention〕

As explained above, the present invention provides a duplexer in which a plurality of filters are arranged, and by providing a metal wall to which an RF power absorber is attached, electromagnetic wave leakage between filters caused by air gaps is prevented by the metal wall. Since the electromagnetic waves can be absorbed by the RF power absorber attached to the filters and prevented from going around between the filters, electromagnetic interference noise generated in the gaps between the filters can be prevented.

[Brief explanation of drawings]

Fig. 1 is an external view showing an embodiment of a duplexer according to the present invention, Fig. 2 is a sectional view taken along line nn in Fig. 1, and Fig. 3 is an external view showing a conventional duplexer. FIG. 4 is a sectional view taken along the line IV-IV. DESCRIPTION OF SYMBOLS 1...Metal housing, 2...Metal plate, 3...Resonance element, 4...Set screw, 5...Gap, 6...
...Metal wall, 7...RF power absorber.

Claims (1)

[Claims] A duplexer in which a plurality of filters each having a resonant element in an RF band and a metal housing housing the resonant element are arranged in parallel, characterized by comprising a metal wall to which an RF power absorber is attached. A branching filter that uses