A CIRCULAR FRACTAL UWB ANTENNA BASED ON DESCARTES CIRCLE THEOREM WITH BAND REJECTION CAPABILITY

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{10.6GHz 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{5.825GHz assigned for IEEE802.11a 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 2dBi to 6dBi in the entire UWB band except the notch band. The performances of time domain characteristic is satisfactory with a group delay variation of 1ns 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 efiectively used for medical imaging and military radar system along with other common UWB applications.