This paper presents a design of a circular monopole antenna for ultra wideband (UWB) applications. The antenna is fed by a 50 SI tapered microstrip line, and printed on a FR4 substrate with relative permittivity of 4.3 and height of 1.6 mm. All optimal parameters of a circular monopole with slot have been presented to accomplish |S11| better than -10 dB with good radiation over UWB frequency. The design includes a modified partial ground plane to enhance the S-parameter characteristics and radiation properties across the whole UWB frequency band. The parameters, which affect the performance of the antenna with respect to frequency characteristics, are investigated and reported.
