In order to obtain a wideband sum-and-difference network, a novel ridged substrate integrated waveguide (RSIW) magic-T is designed. The proposed magic-T is composed of a five-layer RSIW structure. The signal input from the coaxial H-plane port is transmitted to RSIW through a stripline and split into two in-phase and equal signals at the output ports on the top and bottom layers because of the vertically symmetric structure. An E-plane SIW power divider is utilized to realize the E-plane input/output port of the magic-T. A remarkable bandwidth improvement is achieved due to the ridged structure and the wide bandwidth of a ladder-shape stripline optimized by genetic algorithm (GA). Measured results indicate that the magic-T has a fractional bandwidth (FBW) of 78.7% (6.4-14.7 GHz) with return loss better than 18.1 dB and great isolation characteristics.
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