The SIW antenna suffers from the narrow bandwidth for a single cavity and single resonant. Defected ground structure (DGS) with a dual cavity was the solution to solve narrow bandwidth by resulting in hybrid resonance. The hybrid resonance with 14.83% impedance bandwidth is proposed in this antenna design. The first resonance resulted from the combination of the TE101 modes from inner and outer HMSIW cavities while the second resonance resulted from the combination of the strong TE101 and the weak TE102 mode from the inner HMSIW cavity and the addition of the weak TE101 from the outer HMSIW cavity. The measurement antenna design has a broadband antenna with a 14.31% (5.71 – 6.59 GHz) impedance bandwidth by using substrate Rogers RO 5880.

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.