Design of new hybrid-ring, directional coupler using lambda /8 or lambda /6 sections

The authors propose a design method for 1.25 lambda -ring and 7 lambda /6-ring 3-dB directional couplers using lambda /8 and lambda /6 sections, respectively. In addition, the frequency characteristics of the couplings together with the isolations, the return losses, and the phase differences between the output ports are calculated. The method was experimentally verified for a microstrip network, proving its validity for a microwave component with the basic lambda /8 and lambda /6 sections proposed.>