Compact planar magic-T using half mode substrate integrated waveguide and slotline coupling

A new and compact magic-T configuration using half mode substrate integrated waveguide (HMSIW) and slotline coupling is investigated and designed. Due to the metallic ground inserted into the middle of the substrate, the proposed E-plane HMSIW power divider has a 180° reverse phase characteristic between the two input/output ports. A slotline etched in the middle metal ground is utilized to couple the energy out of the HMSIW power divider and functions as the H-arm of magic-T. A Ku-band prototype has been fabricated for demonstration, good agreement between the measured and simulated results has been observed, indicating that the planar magic-T structure has fractional bandwidth of 18.3% (12.9-15.5 GHz), the amplitude and phase imbalances are less than 0.23 dB and 2.0°, respectively. The proposed planar magic-T is expected to find wide applications in the future integration of compact SIW circuits and systems.