A planar monopole antenna using the Penta-Gasket-Koch (PGK) is introduced. The design achieves a good input impedance match and linear phase of S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> throughout the passband (1.5-20 GHz and - 5 dB criterion for impedance bandwidth). But some occasional slight mismatch and small phase distortion occurs at low frequencies. Four different experimental results are shown and the measured gain is generally >4 dBi. For better insight, The S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> performance and input impedance of the proposed antenna are compared with those of the conventional PGK monopole antenna. For analyzing the time-domain characteristics of the antenna, the proposed antenna is assumed to be excited by the three wideband signals corresponding to 1.5-3, 6.0-12, and 13.5-20 GHz which means this antenna can be used as multiband antenna in time domain applications. However, each band consists of wide range of frequency. These bands are selected to examine the time domain response of proposed antennas. For insurability the proposed antenna can be used in pulse communications systems, the correlation between the time-domain transmitting antenna input signal and the receiving antenna output signal is calculated. This antenna is suitable for applications in ICMS, DECT, UMTS, Bluetooth, and WLAN systems. Because of linear phase and good impedance match, with some further optimization and manufacturing aspect, this antenna can serve in UWB applications.