A new small size ring coupler based on fully distributed Composite Right/Left-Handed structures

A new topology of small size ring coupler is proposed. It consists of fully distributed balanced CRLH (Composite Right/Left-Handed) based phase shifters, designed for a frequency which is significantly greater than the coupler operating frequency. Firstly, the equivalent circuit of the ring coupler consisting of ideal transmission lines is designed for operating frequency chosen at 1.8 GHz, and then this circuit is analysed numerically. The coupler layout is also designed and numerically analysed using a 3D electromagnetic simulator. The proposed ring coupler has about 50% smaller area comparing to the conventional configuration, this being an advantage for low operating frequency. Also, comparing to other small size ring coupler topologies reported in the literature, the proposed coupler may be fabricated using standard one mask technological process, as well as for the conventional ring coupler configuration.