# Compact N-Band Tree-Shaped Multiplexer-Based Antenna Structures for 5G/IoT Mobile Devices
## 5 Results and Measurements
The main achievements of these structures are summarized and compared with the current state-of-the-art of dual and tri-band antennas in Table 5, analyzing the publication year (PY), the operating frequencies, bandwidth, size, scalability and the isolation in frequency factor. Knowing that one of the main concerns of this letter is the microstrip frequency-selective feeding network able to maximize the efficiency as well as easing he interaction of a single antenna with multiple RF Frontends, Table 6 compiles some of the state-of-the-art works related to the frequency multiplexing argued, showing how it was obtained and the main characteristics of the antenna structure. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**[Ref.]** & **Antenna’s** & **Central** & **Frequency Isolation** & **Feeding** & **Number of** **Ports/Element** & **Does it Require** **Additional** **Components?** \\ \hline
[14] & Ground Tapered Slot & & & & & \\
2019 & and Microstrip & 2/32.5 GHz & Low-Pass Filter & High & 2 & Yes \\  & Feeders & & & & & \\ \hline
[15] & Antenna Array & 3 GHz & 3 dB directional & & & \\
2016 & & couplers + Schiffman & & & & \\  & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: State-of-the-Art in Frequency Selective Antenna Structures: Main Results. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**[Ref.]** & **Antenna’s Description** & **Operating** & **Bandwidth** & **Measurements** & **Scalability** &
\begin{tabular}{c} **Frequency** \\ **Isolation** \\ \end{tabular} \\ \hline
[2] & Dual-Band Slot-Based & 28/38 GHz &
\begin{tabular}{c} 24–30 GHz \\ 34–41 GHz \\ \end{tabular} & No & No & No \\ \hline
[4] & Series-Fed Antenna Array & 28/38 GHz &
\begin{tabular}{c} 27.8–28.6 GHz \\ 36–38.6 GHz \\ \end{tabular} & No & No & No \\ \hline
[5] & SIW Antenna Array & 28/38 GHz &
\begin{tabular}{c} 0.32 GHz \\ 1.9 GHz \\ \end{tabular} & No & No & No \\ \hline
[6] & Annular Ring Slots & 20/30 GHz &
\begin{tabular}{c} 20.13–20.8 GHz \\ 30–30.85 GHz \\ \end{tabular} & Yes & Yes & No \\ \hline
[7] & Microstrip Patch & 24.4/28/38 GHz &
\begin{tabular}{c} 23.6–24.4 GHz \\ 27.2–28.4 GHz \\ 37.3–38.1 GHz \\ \end{tabular} & No & No & No \\ \hline
[8] & Antenna Array with & 29/37.4/41 GHz &
\begin{tabular}{c} 28.5–29.7 GHz \\ 36.7–38 GHz \\ 40–421 GHz \\ \end{tabular} & No & No & No \\ \hline
[9] & Printed Slot-Based & 2.4/5.2 GHz &
\begin{tabular}{c} 2.48–3.02 GHz \\ 3.81–5.65 GHz \\ \end{tabular} & Yes & Yes & No \\ \hline
[10] & \
\begin{tabular}{c} Aperture-Sharing \\ Technique with a 4 Unit \\ Linear Array and a Dipole \\ \end{tabular} & 3.5/28 GHz &
\begin{tabular}{c} 3.12–3.84 GHz \\ 24.9–30.6 GHz \\ \end{tabular} & Yes & No & No \\ \hline
[11] & Cavity-Backed Antennas & 4.6/5.48 GHz &
\begin{tabular}{c} 91 MHz \\ 20 MHz \\ \end{tabular} & Yes & Yes & No \\ \hline
2019 & using HMSIV Technique & 4.5/5/5.5 GHz &
\begin{tabular}{c} 70 MHz \\ 20 MHz \\ \end{tabular} & Yes & Yes & No \\ \hline
[13] & Fork-Shaped Microstrip & 860/2280 MHz & \begin{tabular}{c} 731–987 MHz \\ 1498–3080 MHz \\ \end{tabular} & No & No & No \\ \hline This & Monopole-Based with & 28/38 GHz & \begin{tabular}{c} 27.54–30.09 GHz \\ 37.2–39.18 GHz \\ \end{tabular} & Yes & Yes & Yes \\ \hline Work & \
\begin{tabular}{c} Frequency Selective \\ Feeding Network \\ \end{tabular} & 20/28/38 GHz &
\begin{tabular}{c} 20.05–20.67 GHz \\ 27.61–28.01 GHz \\ 35.45–37.61 GHz \\ \end{tabular} & Yes & Yes & Yes \\ \hline \hline \end{tabular}
\end{table} 
Table 5: State-of-the-Art of Multi-Band Antennas: Main Results.