Fig.9 Simulated, measured and the equivalent circuit generated
reflection coefficient (|S11|) of the
proposed UWB notch antenna
Variation of the simulated and measured gain vs. frequency in GHz of the
proposed UWB notch antenna is shown in figure 10. From the graph it is
clear that the simulated gain increases almost linearly with frequency
and the range of simulated gain variation is around 5 dBi to 9.5 dBi.
But on the way of linear increase of the simulated gain there is a sharp
drop of gain is exhibited in the graph. At around 5 GHz the gain
decreases at rapid rate and reached peak at 5.5 GHz. After this event
the gain increases and reaches the linearly increasing graph at 6 GHz.
At this notched frequency band of 5 GHz to 6 GHz (WLAN), the proposed
antenna become non-responsive because proposed antenna does not radiate
because of the conjugate effect of the protruding stub and the SRR in
the proposed notch band. The value of the simulated gain at 5.5 GHz is
around -5 dBi. However, for the other frequencies outside the notched
band, the proposed antenna gain is appropriately consistent and almost
stable in the whole of the UWB band. On the other hand, the measured
peak gain is in accordance with the simulated gain and the value of the
measured gain at the 5.5 GHz is around -10 dBi. Hence from this gain vs.
frequency graph it is clear that the proposed UWB notch antenna is
suitable for the operation in the UWB frequency band but simultaneously
notching out the WLAN band for appropriate coexistence.