| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize a double band filter with no use of an external phase shift circuit and also secure the satisfactory pass band characteristic by constructing one of both filters of a double filter constitution based on the input impedance of a pass band or a blocking band with the other filter constructed based on the structure of the former filter and connecting both filters in parallel to each other. SOLUTION: A low band pass filter 2 comprises an input/output capacity pattern 13A, strip lines 14A and 14B and a loading capacity 15B, and a high band pass filter 3 comprises the input/output, loading and inter-stage capacity patterns 18A-18C formed on a dielectric 18 and the strip lines 19A and 19B formed on a dielectric 19, respectively. The input parts and output parts of both filters 2 and 3 are connected to each other. Then the matching of input/ output impedance is secured between the high and low pass bands of both filters 2 and 3, respectively. Thus, the satisfactory pass band characteristics can be obtained at both low and high pass bands and also an external phase shift circuit can be omitted.
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