A novel coupled line 180° hybrid comprises of two modified trans-directional (TRD) couplers and one half-wave transmission line is proposed. The two identical TRD couplers are perpendicular connected to each other at two end points with one directly and the other through a A/2 line section. The proposed hybrid can be easily realized on a single-layer substrate by using general printed circuit board (PCB) technology with a low cost. Modified TRD couplers with arbitrary coupling are presented in the paper to construct the hybrid with simple structure, easy fabrication, and wide range of coupling values. Theoretical analysis of the modified TRD coupler and detailed design procedures of the hybrid is given. To validate the structure, experimental circuit with a 3dB coupling value was also designed and fabricated. Simulation results are compared with the measurements, and a good agreement is observed.
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