In this paper, SICL based 2 × 4 C - shaped Slot Antenna Array fed by Substrate Integrated Coaxial Line (SICL) working in the millimeter wave frequency band is presented. As a starting point for the design, a 1×2 C-shaped Slot antenna array is designed to be operated at 29.35 GHz with a gain of 6.6 dBi The proposed 4×2 C-shaped Slot Antenna Array exhibits high gain of 10.6 dBi at 29 GHz. The 4 sections of the slot antennas array is fed with in-phase field using a SICL power divider. This makes the complete design compact and low profile. The via section encapsulating the middle conductor strip of the SICL section provides good shielding of the feeding network. The designed antenna array has front to back ratio of 17.4 dB. The antenna is useful in LMDS band and possible 5G applications. © 2018 IEICE