Design of Broadband Reduced-Length Directional Couplers Consisting Indirectly Coupled Lines Sections for Planar and MMIC Applications

In this paper a novel design of broadband reduced-length directional couplers for planar and MMIC applications has been presented. The proposed component utilizes two indirectly coupled-lines sections realizing the same coupling coefficient connected with uncoupled transmission-lines. To verify the correctness of the proposed design method, a 3-dB planar directional coupler for 1 GHz center frequency has been designed, fabricated, and measured. Moreover, a monolithic version of the considered solution has been designed for fabrication in the monolithic OMMIC D01PH GaAs technology, operating at 24 GHz center frequency.