A low loss branch line coupler based on substrate integrated suspended line (SISL) technology and double-sided interconnected strip line (DSISL)

This paper proposes a low loss branch line coupler based on substrate integrated suspended line (SISL) technology and double-sided interconnected strip line (DSISL). Compared with conventional suspended line structure, the proposed SISL coupler has the advantages of self-packaging, compact size and low loss. DSISL is introduced in the design to further reduce the losses. A branch line SISL coupler has been designed and fabricated by printed circuit board technology. Simulation results and measurement results show great agreement.