Wave transmission lines and networks – Coupling networks – Frequency domain filters utilizing only lumped parameters
Reexamination Certificate
1999-03-18
2001-06-12
Kinkead, Arnold (Department: 2817)
Wave transmission lines and networks
Coupling networks
Frequency domain filters utilizing only lumped parameters
C361S764000, C361S816000, C361S818000
Reexamination Certificate
active
06246301
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high-frequency circuit apparatus having a printed circuit board provided with high-frequency circuits mounted thereon.
In a multiplex radio communication system, transmitter and receiver portions, such as mobile base station devices, are mounted on a single printed circuit board for the purpose of miniaturization and economy. The receiver and the transmitter mounted on the printed circuit board are isolated by a metal casing or the like. The isolation means can prevent electromagnetic coupling between the transmitter and the receiver through a space on the printed circuit board, but no electromagnetic coupling through the inside of the printed circuit board can be prevented. In particular, if the receiver is of high sensitivity, it is necessary to prevent electromagnetic coupling through the printed circuit board.
2. Description of the Related Art
In a known high-frequency circuit apparatus, an array of plated through holes is provided between the high-frequency circuits to prevent electromagnetic coupling between the high-frequency circuits.
However, only one array of the plated through hole is not enough to sufficiently reduce leakage power. To sufficiently reduce the leakage power, in the conventional high-frequency circuit apparatus, the high-frequency circuits are each covered by a metal casing to isolate them from one another. However, the isolation means such as the metal casing cannot prevent electromagnetic coupling of the circuits through the printed circuit board, as mentioned above, and the high-frequency circuit apparatus becomes large as a whole.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a high-frequency circuit apparatus in which the leakage power is sufficiently reduced without using a metal casing, to thereby prevent an electromagnetic field coupling between the high-frequency circuits.
To achieve the object of the invention, according to a first aspect of the present invention, there is provided a high-frequency circuit apparatus comprising two rows of first plated through holes which connect upper and lower ground plates on the upper and lower surfaces of a printed circuit board and which are arrayed in a first direction so that two high-frequency circuits are disposed between the first plated through holes, and at least two columns of second plated through holes which are arrayed in a second direction different from the first direction, between the two high-frequency circuits to connect the ground plates on the upper and lower surfaces of the printed circuit board.
The rows of the first plated through holes and the ground plates constitute a waveguide which prevents interference with an external signal of the high-frequency circuit apparatus and the second plated through holes, those of the first plated through holes that are located on an extension of the second plated through holes in the second direction, and the ground plates constitute a waveguide resonator whose resonance frequency is identical to an intermediate frequency of signal frequency bands of the two high-frequency circuits and which prevent signals in the signal frequency bands of the high-frequency circuits from passing therethrough.
The two rows of the first plated through holes are spaced at a first distance; the columns of the second plated through holes are spaced at a second distance; the resonance frequency of the waveguide resonator is determined in accordance with the first and second distances; and, the waveguide resonator has frequency characteristics which are determined in accordance with the number and the diameter of the second plated through holes.
Preferably, the high-frequency circuit apparatus further comprises a third plated through hole which connects the ground plates on the upper and lower surfaces of the printed circuit board in the vicinity of a point between the high-frequency circuits at which the intensity of the electric field is maximum; a conductor pattern on the upper surface of the printed circuit board, which is electrically isolated from the ground plate; and a variable capacitance diode which is connected to the third plated through hole and the conductor pattern and whose capacitance is varied in accordance with a bias voltage applied to the conductor pattern.
According to a second aspect of the present invention, there is provided a high-frequency circuit apparatus comprising two rows of first plated through holes which connect upper and lower ground plates on upper and lower surfaces of a printed circuit board and which are arrayed in a first direction so that two high-frequency circuits are disposed between the first plated through holes; at least one row of second plated through holes which are arrayed in parallel with the first plated through hole, between the two high-frequency circuits to connect the ground plates on the upper and lower surfaces of the printed circuit board; two columns of third plated through holes which connect the ground plates on the upper and lower surfaces of the printed circuit board and which are arrayed in a second direction different from the first direction, between the two high-frequency circuits and between one of the two rows of the first plated through holes and the second plated through holes to prevent signal interference between the two high-frequency circuits; and fourth plated through holes which connect the ground plates on the upper and lower surfaces of the printed circuit board and which are arrayed in the second direction different from the first direction, between the two high-frequency circuits and between the two other row of the first plated through holes and the second plated through holes to prevent signal interference between the two high-frequency circuits.
According to a third aspect of the present invention, there is provided a high-frequency circuit apparatus comprising two rows of first plated through holes which connect upper and lower ground plates on upper and lower surfaces of a printed circuit board and which are arrayed in a first direction so that two high-frequency circuits are disposed between the first plated through holes; second plated through holes which connect the ground plates on the upper and lower surfaces of the printed circuit board and which are arrayed to define a rectangle of which one side is defined by one of the two rows of the first plated through holes; and a coupling window opposed to a space defined between the two high-frequency circuits, on one of the rows of the first plated through holes, a width of the coupling window being greater than the distance between those of the plated through holes located on opposite sides of the high-frequency circuits.
According to a fourth aspect of the present invention, there is provided a high-frequency circuit apparatus comprising two high-frequency circuits mounted on a printed circuit board; an upper ground plate formed on an upper surface of the printed circuit board; a lower ground plate formed on a lower surface of the printed circuit board; two rows of first plated through holes which connect upper and lower ground plates on the upper and lower surfaces of the printed circuit board and which are arrayed in a first direction so that the two high-frequency circuits are disposed between the first plated through holes; an intermediate ground plate provided between the upper and lower ground plates and having at the center thereof a coupling window; at least two columns of upper plated through holes which connect the upper ground plate and the intermediate ground plate; at least two columns of lower plated through holes which connect the lower ground plate and the intermediate ground plate.
REFERENCES:
patent: 6094350 (2000-07-01), Achiriloaie
Oyama Jun
Sogo Hiroyuki
Fujitsu Limited
Helfgott & Karas P.C.
Kinkead Arnold
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