Page 265 - 2024-Vol20-Issue2

261 | Majeed

Fig. 2. The fundamental antenna’s reflection coefficient
fluctuation with frequency

Fig. 4. The single rejection band antenna front view

Fig. 3. The fundamental antenna’s gain fluctuation with
frequency

The following formula yields the whole length of inverted Fig. 5. Variation of reflection coefficient versus frequency for

U slot’s shown in Fig. 4: without and with single rejection band cases.

Ltotal = d + 2e + f (2) 2) The Two-Bands Rejection Phase:
To reduce interference from many sources, it is also highly
where d, e, and f stand for the horizontal length, vertical desirable to have notch features at two bands. In order to
length, and the width of the inverted U slot respectively. To achieve this, the single-notch antenna’s radiating patch is
attain the accurate notched center frequency, the inverted U chopped to create a U-shaped slot; the resultant antenna, as
slot dimensions (d, e, f) are adjusted and optimized.It should seen in Fig. 7, is called a dual-notch antenna. The design
be noted that the designed UWB antenna in section 2.1 need process ends with this phase.
to have its dimensions altered in order to accommodate this
slot. The overall length of the U slot can be computed using the
following formula:
As shown in Fig. 4, the slot size was selected using (1)
and (2) to produce a notch at 5.47GHz. The results of the LLtotal = dd + 2ee + f f (3)
simulations indicate that the notch frequency estimated by the
aforementioned method was quite accurate; furthermore, CST
simulation can be used to fine-tune this value.

Fig. 5 and Fig. 6 provide a comparison of the optimized Fig. 6. The variation of realized gain with frequency for
performance with and without a notch in terms of the gain without and with single rejection band cases.
and reflection coefficient. Both figures show that a band of
frequency from 5.09 - 6.18 GHz is rejected with a decreasing
in the gain. The gain stays nearly constant over the whole
band, guaranteeing that the additional slot won’t change the
fundamental antenna’s intended characteristics, but it only
reduces the gain in the rejoin of rejected band.