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.