Dual-Band Artificial Transmission Lines Branch-Line Coupler

By using short-circuited Composite Right/Left-Handed Transmission Lines as loading stubs, and Purely Right-Handed Artificial Transmission Lines, a Dual-Band Branch- Line coupler is presented. The adoption of such technologies adds degrees of freedom with respect to other already proposed design techniques, thus allowing the development of a very compact device, and a larger flexibility in the choice of the two operating frequencies and corresponding bandwidths