Abstract: A novel technique to design broadband and compact SIW cavity-backed array antenna is presented in this paper. The proposed array consists of SIW cavities connected by inductive windows as feeding network and wide slots on the surface of each cavity as radiating part. The SIW cavities are not only used as radiating elements, but also the feeding network. Without loading with extra feeding network, the array is compact. To validate this concept, 2×2 and 4×4 arrays are designed and fabricated at the 20 GHz bands. The simulated and experimental results demonstrate that the proposed arrays have compact structure and excellent radiating performance. Moreover, the method to design high gain and large-scale array is developed in this paper. Based on the proposed 2×2 coupled-fed array, a 16×16 large-scale SIW cavity-backed array antenna is designed and fabricated by employing 8×8 SIW corporate-fed network. The results indicate that the 16×16 array has merits of compact structure, broadband, high gain, and low loss.