Novel two-layer broadband 4 × 4 Butler matrix in SIW technology for Ku-band applications

In this paper, the design of a broadband 4x4 Butler matrix is presented for the first time on a two-layer Substrate Integrated Waveguide (SIW) structure. The presence of path crossings in the matrix structure often imposes the use of extra OdB couplers - usually obtained using back to back pairs of 3dB couplers - for planar realizations. Specific designs that overcome the use of OdB couplers can be found, but these realizations may not be easily generalized to larger matrices. On the other hand, realizations with suspended lines suffer from being narrow band and rather adapted to microstrip technology [4]. A two-layer implementation in SIW technology appears then as a good compromise as it remains compact in height and compatible with both waveguide-like and microstrip technologies.