Fig.11Simulated and measured group delay of the proposed antenna
Figure 12 exhibits the surface current distribution of the proposed
antenna at 3.5 GHz, 4.4 GHz, 5.5 GHz, 8.8 GHz, and 12 GHz. At 3.5 GHz
and 4.4 GHz shown in the figure 12 (a), (b) respectively, the increased
current density is visible in the microstrip feed-line and inner edges
of the square slot in the circular radiating element. Because of this
amount of current density, proper radiation is possible by the proposed
UWB antenna that radiates properly in these operating frequencies. At
notch frequency 5.5 GHz because of the thick rectangular protruding stub
and a SRR printed in the left side of the microstrip feed-line the
proposed UWB notch antenna cannot able to radiate considerably as
depicted in figure 12 (c). At this operating frequency of 5.5 GHz the
current density is very low in the whole structure of the proposed UWB
notch antenna. Similarly, at other frequencies of 8.5 GHz and 12 GHz as
in figure 12 (d), (e) proper radiation happened as the enhanced current
density is visible again in the inner edges of the square slot and
around the edges of the open-ended slit ring.