## 6 Conclusions  
This manuscript successfully demonstrated and implemented a high selectivity and miniaturized triple-band bandpass filter for wireless applications where the first two passbands centred at 1.57 GHz and 3.57 GHz obtained from the ratio of impedances and electrical lengths of the \(\lambda/4\) SIR and the third passband at 4.2 GHz is originated by the embedded L-shaped structure coupled to the low impedance section of the SIR. The \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Ref No.** & **Year** & **Bands (GHz)** & **S\({}_{21}\) (dB)** & **S\({}_{11}\) (dB)** & **FBW (\%)** & **T.Z.s** & **Size (mm)** & **Size (\(\Lambda_{8}\)\({}^{2}\))** \\ \hline \hline
[39] & 2020 & 2.9/5.6/11 & 3/3.1/5 & \(>\)20 & 46/18/6 & 3 & 144 \(\times\) 40 & 1.864 \\ \hline
[40] & 2021 & 2.4/3.5/5.25 & \(<\)1.7 & 50/33/43 & 11.6/4/6.7 & 3 & 41 \(\times\) 29.5 & 0.291 \\ \hline
[41] & 2020 & 1.93/2.6/3.9 & 1.5/0.6/1.8 & 15/20/20 & 5/11/3 & 5 & 17.2 \(\times\) 24.5 & 0.415 \\ \hline
[51] & 2022 & 3.2/3.4/3.7 & 2.65/1.95/2.69 & 18.3/17.9/19.2 & 3.57/3.77/2.07 & 5 & 75 \(\times\) 51.5 & 0.469 \\ \hline
[52] & 2019 & 2.45/3.5/5.25 & 0.7/0.9/0.6 & 38/32/25 & 1.2/2/1.52 & 6 & 42 \(\times\) 31.5 & 0.240 \\ \hline
[53] & 2018 & 0.4/0.8/1.55 & 0.7/1.8/1.6 & 10/8.2/9.3 & 55.4/20.9/10.3 & 5 & 56 \(\times\) 31 & 1.72 \\ \hline
[54] & 2021 & 2.05/2.55/3.1 & 1.98/2.17/2.01 & 12.3/14.9/14.1 & 4.8/7.8/8 & 3 & 72.1 \(\times\) 68.5 & 1.931 \\ \hline
[55] & 2022 & 4.1/6.1/14.4 & 2.1/1.3/4.08 & 19.63/22/12.1 & 5.3/8.6/2.1 & 2 & 22.42 \(\times\) 7.62 & 0.094 \\ \hline
[56] & 2021 & 6.28/13/19.12 & 1.6/2.5/2.2 & 22/26/21 & 9.5/6.2/4.5 & 4 & 8.5 \(\times\) 15 & 0.119 \\ \hline
[57] & 2022 & 4.2/7.36/9.35 & 1.38/4.86/1.27 & 15.7/17/ 38 & 5.21/3.19/9.3 & 4 & 22 \(\times\) 18 & 0.803 \\ \hline
[58] & 2020 & 1.52/2.0/2.36 & 5.32/4.2/6.8 & 15.4/19.1/17.3 & 3.56/8.6/2.75 & 5 & 54.9 \(\times\) 28.6 & 0.248 \\ \hline
[59] & 2022 & 18.2/18.7/19.1 & 2.59/2.21/2.5 & 15.9/20.9/24.8 & 0.45/1.08/0.5 & 6 & 1.1 \(\times\) 1.1 \(\times\) 1.2 & 1.469 \\ \hline
[60] & 2022 & 3.6/4.6/5.6 & \(<\)0.78 & \(>\)30 & 11.9/11.9/11.9 & 5 & 54.34 \(\times\) 22.3 & 0.911 \\ \hline
**This work** & **2023** & **1.57/3.57/4.23** & **0.7/1.2/1.06** & **27/35/28** & **2.54/4.2/1.65** & **8** & **40.1 \(\times\) 22** & **0.086** \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of performance of the proposed filter with other triband structures. Figure 17: Simulated and measured S\({}_{11}\) and S\({}_{21}\) plots of the proposed geometry. fractional bandwidths of 2.54%, 4.2%, and 1.65% and insertion losses of 0.7 dB, 1.2 dB, and 1.08 dB are achieved with rejection levels in the stopband greater than 15 dB and return loss greater than 25 dB for all the three passbands, respectively. There are eight T.Z.s excited at 1.22/1.42/1.98/3.18/3.82/3.98/4.38/4.53 GHz, where the T.Z. at 1.2 GHz and 3.98 GHz are due to mixed-coupling of the SIR, the 1.42 GHz and 3.82 GHz by the SIR itself, the 1.98 GHz and 3.18 GHz are excited due to the metallic via at lower end of the SIR, and the last two are generated due to L-shaped structure coupled to the SIR, thus obtained a high sharp filter. Lastly, the structure was fabricated on Rogers PCB and observed an excellent matching between experimental and measured results. Owing to the above features, the prototype can be successfully implemented in real-world applications such as GPS, WiMAX, and Satellite communication systems. The author claimed that this work is the second high sharp filter along with the compact size and simple topology in the literature by introducing multiple T.Z.s in the passbands. Conceptualization, A.B. and G.Z. ; methodology, A.B. ; software, A.B., S.A.A., M.I.K. and A.D.; formal analysis, A.D.; investigation, A.B. ; resources, S.A.A. and F.Z. ; data curation, F.Z. ; writing--original draft preparation, A.B. ; writing--review and editing, G.Z. ; visualization, A.B. and A.D.; supervision, G.Z. ; project administration, G.Z. ; funding acquisition, G.Z.