Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
1999-09-01
2001-10-09
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C333S109000, C333S124000
Reexamination Certificate
active
06300848
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power splitter and a power combiner mainly used for a microwave circuit.
2. Description of the Related Art
For the circuit configuration of a conventional power splitter, there is a method of combining the 3-dB directional couplers shown in FIG.
5
.
FIG. 5
is a four-way power splitter , in which symbol
31
denotes an input terminal,
32
a
to
32
d
denote output terminals, and
33
a
to
33
c
denote 3-dB directional couplers. Though circuit design is easy for the circuit configuration in
FIG. 5
, there are disadvantages that the circuit scale increases when the number of split s increases, the insertion loss increases, and only a 2
n
-way power splitter can be constituted.
Therefore, for the circuit configuration of a compact and small-loss four-way power splitter , there is a method of cascading the directional couplers having coupling degrees 6, 4.7, and 3 dB shown in FIG.
6
. In
FIG. 6
, symbol
41
denotes an input terminal,
42
a
to
42
d
denote output terminals,
43
denotes a 6-dB directional coupler,
44
denotes a 4.7-dB directional coupler, and
45
denotes a 3-dB directional coupler. Operations of the four-way power splitter constituted as shown in
FIG. 6
are described below.
An input signal (P) input through the input terminal
41
is first input to the 6-dB directional coupler
43
, {fraction (1+L /4)} the input signal (P), that is, a (P/
4
) signal is output to the output terminal
42
a
, and the remaining (
3
P/
4
) signal is input to the 4.7-dB directional coupler
44
. Next, the 4.7-dB directional coupler
44
outputs ⅓ the input signal (
3
P/
4
), that is, a (P/
4
) signal to the output terminal
42
b
and inputs the remaining (P/
2
) signal to the 3-dB directional coupler
45
. Then, the 3-dB directional coupler
45
divides the input signal (P/
2
) into two equal signals, outputs a (P/
4
) signal to output terminals
42
c
and
42
d
respectively, and operates as a four-way power splitter.
FIG. 7
shows a case in which the configuration in
FIG. 6
is constituted of a conventional branch-line-shaped directional coupler. In
FIG. 7
, symbols
51
and
52
denote transmission lines,
53
,
54
, and
55
denote terminating resistors,
43
a
denotes an input port,
43
b
denotes an isolation port,
43
c
denotes a first output port, and
43
d
denotes a second output port, and a component same as that in
FIG. 6
is provided with the same symbol.
In the case of the configuration in
FIG. 7
, however, a branch-line-shaped directional coupler having a large coupling degree is necessary when the number of split s increases. To constitute the above directional coupler, a transmission line having a high characteristic impedance or generally, a microstrip line is necessary. Thus, the configuration as problems that loss increases because the strip line width decreases and the machining accuracy is limited.
BRIEF SUMMARY OF THE INVENTION
The present invention is made to solve the problems of the conventional power splitter and its object is to provide a power splitter capable of increasing the number of splits or reducing loss, as compared with conventional cases.
It is another object of the present invention to provide a power combiner capable of using input ports more than ever and reducing loss compared with a conventional case in the case where the powers supplied from a plurality of inputs are combined and then output.
One aspect of the present invention is a power splitter comprising:
N branch-line-shaped directional couplers respectively constituted of four quarter-wavelenglh lines and having an input port, an isolation port, a first output port, and a second output port;
an input line; and
N+1 output lines, wherein
(a-1) when the impedance of the input line is equal to the impedance of the input port of the first branch-line-shaped directional coupler, the line and the port are connected through a transmission line having an impedance equal to the above impedance or directly connected and (a-2) when the former impedance is different from the latter impedance, the line and the port are connected through a first impedance converter,
(b-1) when the impedance of the second output port of the Kth (K=1, 2, . . . , N−1) branch-line-shaped directional coupler is equal to the Impedance of the input port of the (K+1)th branch-line-shaped directional coupler, the output port and the input port are connected through a transmission line having an impedance equal to the above impedance or directly connected and (b-2) when the former impedance is different from the latter impedance, the output and input ports are connected through a Kth impedance converter,
(c-1) when the impedance of the second output port of the Nth branch-line-shaped directional coupler is equal to the impedance of the (N+1)th output line, the output port and the output line are connected through a transmission line having an impedance equal to the above impedance or directly connected and (c-2) when the former impedance is different from the latter impedance, the output port and the output line are connected through an (N+1)th impedance converter, and,
when (1) the input port and the second output port are used as a first terminal pair and (2) the isolation port and the first output port are used as a second terminal pair, the impedance of the first terminal pair is different from the impedance of the second terminal pair in at least one of the N branch-line-shaped directional couplers.
Another aspect of the present invention is the power splitter, wherein the impedance of the second terminal pair is constituted as a reference impedance.
Still another aspect of the present invention is the power splitter, wherein
the impedance of the first terminal pair is constituted as a reference impedance, and
(d-1) when the impedance of the first output port of a Jth (J=1, 2, . . . , N−1) branch-line-shaped directional coupler is equal to the impedance of a Jth output terminal, the output port and the output terminal are connected through a transmission line having an impedance equal to the above impedance or directly connected and (d-2) when the former impedance is different from the latter impedance, the output port and the output terminal are connected through a Jth output impedance converter.
Yet another aspect of the present invention is the power splitter, wherein the coupling degree of the Kth branch-line-shaped directional coupler is equal to 10×log
10
(N−K=2) (dB), (K=1, 2, . . . , N).
Still yet another aspect of the present invention is the power splitter, wherein the product between the impedance of the second output port of the Kth (K=1, 2, . . . , N−1) branch-line-shaped directional coupler and the impedance of the input port of the Kth branch-line-shaped directional coupler is equal to the second power of the characteristic impedance of the quarter-wavelength line between the input port and the second output port of the Kth branch-Line-shaped directional coupler.
A further aspect of the present invention is the power splitter, wherein the product between the impedance of the second output port of the Kth (K=1, 2, . . . , N−1) branch-line-shaped directional coupler and the impedance of the input port of the (K+1)th branch-line-shaped directional coupler is equal to the second power of the characteristic impedance of the quarter-wavelength line between the input port and the second output port of the (K+1)th branch-line-shaped directional coupler.
A still further aspect of the present invention is the power splitter, wherein the product between the impedance of the first output port of the Jth (J=1, 2, . . . , N−1) branch-line-shaped directional coupler and the impedance of the Jth output terminal is equal to the second power of the characteristic impedance of the quarter-wavelength line between the isolation port and the first output port of the Jth branch-line-shaped directio
Ishida Kaoru
Kosugi Hiroaki
Kugou Shin'ichi
Miyaji Masayuki
Glenn Kimberly E
Matsushita Electric - Industrial Co., Ltd.
Pascal Robert
Ratner & Prestia
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