# A Four-Port Dual-Band Dual-Polarized Antenna for Ku-Band Satellite Communications
## 4 Conclusions  
A four-port shared-aperture DBDP antenna for Tx/Rx Ku-band SATCOM applications was developed, fabricated, and tested. The antenna was designed using the multilayer printed circuit board technology, consisting of an LB \(L\)-probe proximity-fed square-ring antenna and a HB stacked-patch antenna, sharing a common aperture. Through the experiment, an IBW of 9.28-12.96 GHz (13.21-15.32 GHz), an isolation value between two orthogonal polarizations of 12 dB (12.4 dB), and a peak gain of 6.63 dBi (5.42 diBi) were achieved at the low band (high band). The Tx/Rx isolation was more than 14 dB in both the  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Ref.**} & **IBWs** & **Peak Gain** & **Frequency** & **Tx/Rx** & \multirow{2}{*}{**Size [\(\lambda_{L}^{2}\)]**} \\  & **LB/HB [\%]** & **LB/HB [dBi]** & **Ratio** & & **Isolation** & \\ \hline
[13]\({}^{\star}\) & 23.7/12.8 & N.M. & 1.7 & \textgreater{}17 & 0.64 \(\times\) 0.64 \\
[14]\({}^{\star}\) & 22/16 & 5.0/5.0 & 1.5 & N.M. & 50 \(\times\) 0.50 \\
[15] & 28.3/29.4 & 7.04/6.94 & 2.0 & N.M. & 0.83 \(\times\) 0.83 \({}^{\star\star}\) \\
[16]\({}^{\star}\) & 8.0/10.0 & 8.7/8.3 & 2.0 & N.M. & 0.75 \(\times\) 0.75 \\
[17] & 13.7/5.3 \({}^{\star\star}\) & 8.0/7.0 & 1.2 & \textgreater{}17 & 0.86 \(\times\) 0.86 \\ Proposed & 33.10/14.79 & 6.63/5.42 & 1.2 & \textgreater{}14 & 0.56 \(\times\) 0.56 \\ \hline \hline \end{tabular} \(\lambda_{L}\) is the free space wavelength at the center frequency of the low band. \({}^{\star}\) Simulated. \({}^{\star\star}\) Estimated from graph. N.M.: not mentioned.  
\end{table}
Table 1: Comparison with previous DBDP antennas.  
Figure 10: Simulated and measured normalized radiation patterns of the proposed antenna at (**a**) 11.75 GHz, fed by **P1**, (**b**) 11.75 GHz, fed by **P2**, (**c**) 14 GHz, fed by **P3**, and (**d**) 14 GHz, fed by **P4**.  
Rx band and Tx band. The proposed antenna exhibits dual-band dual-polarized operation, covering two frequency bands, 10.7-12.75 GHz (Ku-band downlink) for Rx mode and 13.75-14.5 GHz (Ku-band uplink) for Tx mode; therefore, it can be directly used as a basic unit to develop a Ku-band Tx/Rx phased array for LEO SATCOM applications. This is considered the future work of the proposed design. In addition, the design can easily be scaled to operate in the Ka band (27.5-31 GHz for uplink and 17.7-21.2 GHz for downlink).  
Conceptualization, S.T.-V., W.Y.Y., H.W.C. and K.C.H.; methodology, S.T.-V. and K.C.H.; software, S.T.-V.; validation, S.T.-V., W.Y.Y., H.W.C. and K.C.H.; formal analysis, S.T.-V.; investigation, S.T.-V. and K.C.H.; resources, S.T.-V. and K.C.H.; data curation, S.T.-V., W.Y.Y., H.W.C. and K.C.H.; writing--original draft preparation, S.T.-V.; writing--review and editing, S.T.-V., W.Y.Y., H.W.C. and K.C.H.; visualization, S.T.-V.; supervision, K.C.H.; project administration, K.C.H. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Research Fund of Hanwha Systems (Hanwha Phasor).  
Not applicable.  
All data have been included in study.  
Authors [PERSON] and [PERSON] were employed by the The UK Office (Hanwha Phasor). The authors declare that this study received funding from Hanwha Systems (Hanwha Phasor). The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication.