Coupled-Line Directional Couplers for M.I.C.

Following a general consideration of the concept of directional couplers in an inhomogeneous medium and physically asymmetrical couplers, this paper reviews various new types of MIC couplers carring, sometimes simultaneously, different propagation modes (microstrip, coplanar line, slot 1ine). Experimental results are presented for the performance obtained with a 2.2. dB coupler of simple design of the "microstrip - coplanar" type.