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.