V. CONCLUSION
A new compact microstrip line fed printed UWB notch monopole antenna of dimension 15x17 mm2 having a circular radiating element with a square slot is proposed. For generation of a WLAN notch band of 5 GHz to 6 GHz with notch frequency center 5.5 GHz a thick protruding stub is erected down from top portion of the square slot in the circular radiating patch. For the purpose of impedance matching an open-ended slot etched out in the middle portion of ground plane just below the microstrip feed-line and an open-ended square slit ring is printed in the upper portion of the protruding stub. For the proper tuning of the center of the notch frequency and also proper impedance matching, a SRR is printed on the left side of the microstrip feed-line. Hence this antenna structure configuration is simulated and the bandwidth obtained is from 3.09 GHz to 13.32 GHz having the percentage bandwidth of 125 which covers the entire UWB frequency band. Along with this band a deep notched band is obtained from 5 GHz to 6 GHz with notch frequency center 5.5 GHz to mitigate the interference of the WLAN band (5-6 GHz) with the UWB operating system for suitable coexistence. The proposed antenna is fabricated and the antenna parameters such as reflection coefficient, gain, group delay is effectively measured. The measured proposed antenna parameters are in accordance with the simulated parameters. Equivalent circuit analysis of the proposed antenna is performed and the reflection coefficient obtained through the equivalent circuit analysis is effectively matched with its simulated and measured reflection coefficient. Stable radiation pattern and consistent gain is provided by the proposed UWB monopole notch antenna in the UWB frequency range as well as the in the notch band. The average measured gain of this proposed antenna was found to be 7.1 dBi. The measured group delay is consistent in the UWB frequency domain which is around 0.2 ns. Time domain analysis is performed and the UWB pulse transmission through the proposed UWB notch antenna is thoroughly examined. From the time domain analysis, it is clear that the proposed UWB notch antenna has excellent pulse handling capability in the UWB system. The proposed antenna is highly compact in nature and its characteristics are compared with other similar UWB notch antennas in the literature. From this comparison it is clear that the UWB notch antenna which is proposed performs superiorly with the other contemporary UWB notch antenna and is expected to find future applications in UWB systems for coexistence with the WLAN systems.
ACKNOWLEDGMENTS
The authors thanks to Prof. (Dr) S K S Parashar, Department of Physics, School of Applied Science KIIT (Deemed to be University) for allowing his laboratory for measurements of various antenna parameters of the proposed antennas.