Many applications in communications and radars require circular or dual linear polarization, and the flexibility afforded by microstrip antenna technology has led to a wide variety of designs and techniques to fill this need. In recent years, the demand for compact mobile telephone handsets has grown. Handsets with size of a pocket have begun appearing in the market and, as the demand for increased electronic mobility grows, the need for small handsets will most likely increase. A small antenna size is required as one of the important factors in portable mobile communication systems. Various...