Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Reexamination Certificate
2000-07-10
2001-10-23
Bettendorf, Justin P. (Department: 2817)
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
C333S204000, C333S219100
Reexamination Certificate
active
06307449
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a filter circuit for filtering a high frequency signal of the microwave band or the millimeter wave band.
2. Description of the Prior Art
A filter including resonators on a printed circuit board contained in a metal box for filtering an input signal of the microwave band or the millimeter wave band through the resonators is known. Such a prior art filter is disclosed in Japanese patent application provisional publication No. 7-202507.
FIG. 11
is a plan view, partially cross-sectional view, of this prior art filter. An input signal is transferred by resonators
1
a
top
1
c
on a substrate
2
contained in a box to output the filtered signal. A radio wave absorbing material
9
is provided on the inside walls of the case
8
to suppress disturbance in electromagnetic mode and to suppress generation of harmonics to reduce noise.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide a superior filter.
According to the present invention there is provided a first filter including: a substrate; at least a connector for providing electrical connection; a filter circuit on a top surface of the substrate including at least a resonator electromagnetically resonating at a resonance frequency at a microwave band and a millimeter wave band, for filtering an input signal from the connection means through the resonator and outputting the filtered signal through the connector; a metal box including a top plate confronting the top surface and the filter circuit, side walls, and a bottom plate, for containing and supporting the substrate and filter circuit, a portion of the side walls supporting the connector, wherein a first portion of the input signal is transferred through the filter circuit and a second portion of the input signal is transferred through a portion of the metal box in the wave-guided mode, the second portion providing a spurious characteristic of the filter, an inside surface of the top plate having a shape other than a plane to control the spurious characteristic.
In the first filter, the inside surface may have a hollow portion.
In the first filter, the top plate has a thickness between a top surface thereof and the inside surface and the thickness may successively increase and then, successively decrease in a direction.
In the first filter, the top plate has a thickness between a top surface thereof and the inside surface and the thickness may decrease stepwise and then, increase stepwise in a direction.
In the first filter, the inside surface may have at least triangle pole.
In the first filter, the inside surface may have a plurality of triangle poles arranged in a direction.
In the first filter, the inside surface may have a protruding portion and the protruding portion and the top plate are monolithic.
According to the present invention there is provided a second filter including: a substrate; at least a connector for providing electrical connection; a filter circuit on a top surface of the substrate including at least a resonator electromagnetically resonating at a resonance frequency at a microwave band and a millimetric wave band, for filtering an input signal from the connection means through the resonator and outputting the filtered signal through the connector; a metal box including a top plate confronting the top surface and the filter circuit, side walls, and a bottom plate, for containing and supporting the substrate and filter circuit, a portion of the side walls supporting the connection means, wherein a first portion of the input signal is transferred through the filter circuit and a second portion of the input signal is transferred through a portion of the metal box in a guided mode, the second portion providing a spurious characteristic of the filter, the side wall having a protruding portion to control the spurious characteristic.
According to the present invention there is provided a second filter including: a substrate; at least a connector for providing electrical connection; a filter circuit on a top surface of the substrate including at least a resonator electromagnetically resonating at a resonance frequency at a microwave band and a millimeter wave band, for filtering an input signal from the connection means through the resonator and outputting the filtered signal through the connection means; a metal box including a top plate confronting the top surface and the filter circuit, side walls, and a bottom plate, for containing and supporting the substrate and filter circuit, a portion of the side walls supporting the connector; a dielectric plate on an inside surface of the metal box on the side of the top surface, wherein a first portion of the input signal is transferred through the filter circuit and a second portion of the input signal is transferred through a portion of the metal box and the dielectric plate in a guided mode, the second portion providing a spurious characteristic of the filter, the dielectric plate controlling the spurious characteristic.
In the first to third filters, the resonator may include a microstrip line.
In the first to third filters, the resonator may include a patch resonator.
In the first to third filters, the resonator may include a dielectric resonator.
In the first to third filters, the side walls may be combined with the bottom plate.
In the first to third filters, the side walls may be combined with the top plate.
In the first to third filters, the filter may include a connector.
REFERENCES:
patent: 3958194 (1976-05-01), Klein et al.
patent: 4020428 (1977-04-01), Friend et al.
patent: 4138652 (1979-02-01), Nishikawa et al.
patent: 4142164 (1979-02-01), Nishikawa et al.
patent: 4237434 (1980-12-01), Cappucci
patent: 4692723 (1987-09-01), Fiedziuszko et al.
patent: 5025235 (1991-06-01), Pramanick
patent: 5172084 (1992-12-01), Fiedziuszko et al.
patent: 58-63201 (1982-04-01), None
patent: 61-159805 (1984-07-01), None
patent: 59-114904 (1984-07-01), None
patent: 60-248001 (1985-12-01), None
patent: 6-177605 (1994-06-01), None
patent: 7-202507 (1995-08-01), None
patent: 226193 (1959-04-01), None
Jasberg, “Improvement of Power Output from Pulsed Kystrons,” Proceedings of IRE vol. 2, No. 5, May 1954.
Makimoto Mitsuo
Matsuo Michiaki
Yabuki Hiroyuki
Bettendorf Justin P.
Israel Gopstein
Matsushita Electric - Industrial Co., Ltd.
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