Page 266 - 2024-Vol20-Issue2
P. 266
262 | Majeed
Fig. 9. Comparison of gain variations with frequency for
without rejection band, with single rejection band, and with
two rejection bands cases.
Fig. 7. The dual rejection band antenna front view. TABLE I.
THE SUGGESTED UWB ANTENNA’S OPTIMIZED
where dd, ee and ff stands for the horizontal length, the vertical DIMENSIONS WITH DUAL-REJECTION BANDS
length, and the width of the U-shaped slot respectively. PROPERTIES.
Eq. 1 and Eq. 3 were used to design the U-shaped slot Parameter Value(mm) Parameter value(mm)
such that it would display a notch at 7.8 GHz. L 2.45 e 3.87
Figs. 8 and 9, respectively, compare the three antennas opti- W 2.45 f 0.19
mal performance in terms of gain and reflection coefficient. slx 10.9 dd 4.3
Fig. 8 illustrates the rejection of the two-bands, the first band sly 5.9 ee 3.9
covers 4.87 - 5.79 GHz and the other covers 7.2 - 8.45 GHz a 4.65 ff 0.22
without impacting the first band. It was found that, depending b 5.4 Lf 6.96
on the precise need, both rejected bands may be independently d 7.96 Wf 1.97
moved to the right or left utilizing variations in length of slot.
According to Fig. 9, the first notched band achieves a mini- tested experimentally to confirm the suggested antenna design
mum gain of-1.72 dBi at frequency of 5.42 GHz, whereas and assess the dual rejection antenna functionality. Fig. 10
the second notched band achieves a minimum gain of 0.83 dBi shows a photo of constructed suggested UWB antenna of dual
at frequency of 7.8 GHz. According to the aforementioned rejection bands features.
gain values, there was a decrease of 4.97 dB and 2.89 dB,
respectively, from the situation before the additions of the The reflection coefficients simulation and measurement
notches. results for the dual-band rejected antennas are compared in
Fig. 11. Reflections from the cable connectors and the sur-
III. EXPERIMENTAL RESULTS rounding measuring environment are the source of the quick
fluctuations in the measured results. The figure illustrates
Using the optimized dimensions listed in Table ??, the an- how well the measured and simulated outcomes match the de-
tenna geometry depicted in Fig. 7 was manufactured and sign’s validation. The little differences between the simulated
and measured values can be attributed to both the fabrication
Fig. 8. Variation of reflection coefficient with frequency errors and the measuring environment.
comparison for without, with a single rejection band and with
dual rejection band cases. The gain’s simulated and measurement results of the sug-
gested antenna is displayed in Fig. 12. The figure shows that
adding two slots to the patch causing decrease in the antenna
gain to lower levels at two rejection frequencies.
The 3D radiation patterns of suggested antenna with and
without notches are displayed in Figure 13. This figure shows
that the radiation efficiency of the antenna decreased to-3.2598 dB
at the first notch frequency of5.42 GHz when it had two
notches, and to -0.3381 dB when it had none.At the sec-
ond notch frequency 7.8 GHz, the radiation efficiency was
-0.631 dB in the absence of notch, but with the existence of
two notches, it dropped to -1.429 dB.
