The miniaturization of substrate-integrated waveguide (SIW) antenna suffers from the narrow impedance bandwidth. It occurs on the quarter mode substrate integrated waveguide (QMSIW) antenna that has 75% miniaturization of the full mode SIW. This research proposed the bandwidth enhancement for QMSIW antenna by using dual cavity and triangle slot. The QMSIW antenna feeds in a single port. The impedance bandwidth simulation has an 8.6% fractional bandwidth improved with dual resonant frequencies. The simulation result was validated with the measured impedance bandwidth.