A novel planar circular Apollonian fractal shaped UWB monopole antenna with band rejection capability is presented in this paper. The antenna performs satisfactorily in the frequency range 1.8-10.6 GHz which gives a wide impedance bandwidth of 142% for VSWR within 2. The proposed antenna has the capability to reject the frequency band 5.125-5.825 GHz assigned for IEEE802.11 a and HIPERLAN/2. This is achieved by a pair of narrow band resonant L-shaped slots in the CPW ground plane. The antenna exhibits satisfactory omnidirectional radiation characteristics throughout its operating band. The measured peak gain varies from 2 dBi to 6 dBi in the entire UWB band except the notch band. The performances of time domain characteristic is satisfactory with a group delay variation of 1 ns that shows the antenna is non dispersive. To ensure the usefulness of the proposed antenna in pulse communications systems, the correlation between the time-domain transmitting antenna input signal and the receiving antenna output signal is calculated. This antenna can be effectively used for medical imaging and military radar system along with other common UWB applications.
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