A wideband substrate integrated waveguide (SIW) antenna topology is proposed for operation in the 60 GHz band. It consists of two coupled quarter-mode and one halfmode SIW resonant cavities. This novel approach combines a significant bandwidth enhancement and a small footprint with compatibility to low-cost, standard PCB fabrication technology, making it excellently suited for 5G high-datarate wireless applications. Exploiting SIW technology, a high antennaplatform isolation is obtained, enabling high-density integration with active electronics without the risk of harmful coupling. An antenna that covers the entire 60 GHz IEEE 802.11ad band is designed, with a measured fractional impedance bandwidth of 11.7% (7 GHz). The measured maximum gain and radiation efficiency of the prototype amount to more than 5.1 dBi and 65%, respectively, within the entire impedance bandwidth. Index Terms-Substrate integrated waveguide (SIW) antenna, coupled resonators, half-mode SIW (HMSIW), quarter-mode SIW (QMSIW), wideband, 60 GHz. I.