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A theoretical study of the properties of "constant-phase" two-ports is presented which leads to a simple experimental synthesis technique for a broad class of microwave band-pass filters. "Constant-phase" two-ports consisting of modified step-twist-junctions are employed in experimental multiple cavity direct-coupled filter configurations which have the unique property of continually adjustable bandpass characteristics and fixed center frequency. These experimentally obtained characteristics are predicted from the theory.
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B.C. DeLoach (1964) studied this question.
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