This document discusses microstrip patch antennas. It begins by defining an antenna and describing different types, including microstrip antennas. Microstrip antennas consist of a radiating patch on one side of a dielectric substrate, with a ground plane on the other side. They are commonly used due to their low cost, lightweight construction, and design versatility. Various patch shapes and feeding techniques are described. Applications discussed include mobile communications, satellites, sensors, and GPS. Key specifications like return loss and input impedance are also covered.