Fig. 4 Chronological developenent of the proposed antenna with
last two iterative processes.
Figure 5 shows the simulated reflection coefficient
(|S11|) of iteration five and six of
the final proposed design of the UWB notch antenna. In iteration five
shown in figure 4 (a), an open-ended slit ring is created on the top of
the protruding stub in the square slot of the circular radiating
element. Due to the open-ended slit ring in the top portion of the
protruding stub, the operation band is extended from 2.8 GHz to 12.8 GHz
with impedance bandwidth 10 GHz which is 0.6 GHz more than the impedance
bandwidth obtained in iteration four. The reason for the enhancement of
the impedance bandwidth is due to creation of the extra current paths
through open ended slit ring. This enhanced current path helps in the
constructive addition of currents in the edges of the open-ended slit
ring and the protruding stub. But in this iteration the position of the
center of notch frequency is unmoved at fns1= 4.7
GHz as in fourth iteration. Hence there is no improvement of the
position of the center frequency of the notch i.e.fns1= 4.7 GHz.