A capacitively loaded planar inverted F antenna (PIFA) for a portable RFID application is presented. The antenna consists of four parts: a ground plane, a rectangular radiator with cut slots, an excited stub, and a shorting pin on the right-hand side that connects the ground plane to the rectangular radiator. The excited stub and the rectangular radiator are forms capacitive coupling. The capacitive coupling and shorting pin are used to effectively reduce the antenna size. Parametric studies of the proposed antenna are discussed to understand the operating mechanism and to produce a brief design guideline. The proposed antenna is easy to integrate in radio frequency devices for low manufacturing costs.