A novel compact SIW cavity-backed antenna sub-array and its application in large-scale array design

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, a 2×2 array and a 4×4 array are designed and fabricated at the 20-GHz bands. The experimental results demonstrate that the proposed arrays have large bandwidth, compact structure and can be used as sub-array for large-scale array design. Using the proposed 2×2 array antenna, a 16×16 large-scale SIW cavity-backed array antenna is designed and fabricated with PCB technique. On the top layer, the 2×2 sub-arrays are employed as radiating elements. On the bottom layer, 8×8 SIW corporate-feed network is constructed to feed the sub-arrays. This compact sub-array structure can significantly reduce the separation distance of elements to alleviate the grating lobes.