In this chapter, the authors present different techniques used to miniature microstrip antennas, particularly planar antennas array, for different applications demanding small dimensions. This will cover DGS, slot technique, and metamaterials. After the presentation of these techniques based on theoretical studies, the second part of this chapter will be about the authors' contribution in the miniaturization of microstrip antennas arrays. This part will include the presentation of some miniature antennas array which they have validated into simulation and measurement by using DGS techniques. The different structures were validated into simulation by using tow electromagnetic solvers ADS (advanced design system) and CST-MW (computer simulation technology) which permit one to validate and to verify the different performances of antennas arrays as radiation pattern, matching input impedance and small dimensions.