We have proposed an open terminated folded inverted-L antenna (FDA) with slits. In order to miniaturize the FILA, several slits arc employed on the substrate surface. Folded structure is used for broadbanding. Design of the FILA to achieve broadband characteristics is shown. Simulation and measurement are implemented, and comparison of the results are evaluated.Finally, we calculate the product of bandwidth and radiation efficiency (B eta product) and evaluate it of the FILA compared with the theoretical limitation.