Compact foldable coupled-line cascade couplers

Abstract

A novel coupled-line coupler structure is proposed based on the asymmetric cascade connection of the coupled lines. The effective size of the proposed coupler can be made smaller than conventional quarter-wavelength couplers. Also, the increased design freedom offered by the proposed structure makes it convenient to adapt its layout to complex circuit routing environments within limited area, e.g. the coupled-line couplers bent at arbitrary angles.