This paper describes a simple modified planar monopole antenna able to cover the 2.4 GHz ISM band as well as the band required for FCC's UWB regulation. The proposed design is based on the well-known semi-circular planar monopole and in order to minimize the return loss in the two bands, the structure is composed of two simple radiating elements, each being efficient in its targeted band. Simulation results in terms of return loss, directivity, radiation pattern and surface current distribution show that the proposed compact modified circular monopole satisfies the requirements of short-range communication antenna in the two bands of interest.