Wiggly technique for broadband non-uniform line couplers

A new and successful wiggly technique is proposed for the design of broadband non-uniform line couplers, where the coupler is wiggled with rectangular teeth on the inner and outer edges of coupled conductors. Compared with other reported quadrature couplers, this design offers a fully planar structure without bond wires or dielectric overlaps. A fabricated 2-18 GHz microstrip coupler was measured and significant performance improvement is reported.