We designed an electrically small antenna (ESA) with coplanar waveguide (CPW) matching circuit. Matching circuit is realized by using interdigital gap and transmission line. Our ESA has one-sided directivity for IMS band application. By using and controlling the length of floating metal layer on the bottom side, we can realize the one-sided radiation on the thinner substrate than that of the standard patch antenna. We also made experiments on the ESA with CPW matching circuit using patterned circuit board.