The substrate-integrated waveguide (SIW) technology is utilized as an alternative low-cost approach in fabricating cavity-backed patch antennas. The proposed antenna arrays combine the attractive features of the conventional metalized cavity-backed patch arrays like surface wave suppression, high radiation efficiency, and enhanced bandwidth, yet provide a low manufacturing cost. A previously developed design of a 2×2 SIW cavity-backed microstrip patch sub-array is extended here and used as a basic building block to attain larger arrays of 2 × 4, 4 × 4, and 8 × 8 elements. The fabricated arrays have been measured and demonstrate good agreement with their simulated performance. The design and performance of these arrays are compared to other conventional bandwidth enhancement techniques, which prove SIW as a viable alternative.