In this paper, a wideband monopole antenna with ring loop by modified ground plane is presented. The proposed antenna consist of monopole antenna, ring loop by ground plane. This antenna is fed CPW-fed and wide slot antenna of a novel structure for broadband characteristics is proposed. To enhance the impedance bandwidth of the wide slot antenna, we proposed the wide slot structure with CPW-fed which is combined with four ${lambda}/2$ rectangular radiation modified monopole and inductively coupled. The measured impedance bandwidth is about 2.5 GHz(3.65~6.15 GHz) then less -10 dB.