ABSTRACT A novel wideband dual cavity backed substrate integrated waveguide antenna is presented in this paper. The properties of dual cavity backed substrate integrated waveguide (SIW), U‐iterative slot design and dumbbell shaped defected ground structure has remarkably improved the bandwidth of the proposed antenna design. The proposed antenna achieves high gain, wide bandwidth, wide beam‐width, good FBR and high radiation efficiency in a compact design. A 2 × 2 MIMO dual cavity backed SIW ant