In this paper, a modified magic-T using substrate integrated waveguide (SIW) and slotline is proposed and developed for RF/microwave applications on the basis of the substrate integrated circuits (SICs) concept. The modified planar magic-T consists of an 1800 phase-reversal T-junction and an H-plane SIW T-junction. An optimized wideband magic-T structure is demonstrated and fabricated. Measurement of this structure shows very promising results. Also, theoretical analyses are presented and discussed with transmission line models of the modified magic-T. Measured results of the circuit agree well with its simulated ones.