Compact Planar Magic-T Based on the Double-Sided Parallel-Strip Line and the Slotline Coupling

Two compact planar magic-T structures implemented on the double-sided parallel-strip line (DSPSL) and the slotline coupling are proposed and demonstrated. Due to a metallic ground inserted into the middle of the substrate for the double-sided parallel-strip line, the E-plane DSPSL power divider thus shows an intrinsic 180° out-of-phase characteristic between the two input/ output ports. A transition between slotline and DSPSL is utilized to realize the H-plane input/output port of the magic-T. The equivalent circuits are derived for the design of the proposed planar multilayer magic-T. Good agreement between the measured and simulated results indicates that the fractional bandwidths for the two planar magic-T structures are 42.8% and 43.8%, respectively, while the amplitude and phase imbalance are less than 0.22 dB and 1.5°.