# Conceptual Design of a Semi-Dual Polarized Monopulse Antenna by Computer Simulation
## 4 Conclusions  
A design of a high-performance Ku-band reflector monopulse antenna with a dual-circularly polarized sum and two linearly polarized difference channels has been presented for signal and target tracking applications at 14.5-16 GHz. The novelty of the proposed antenna is that the implementation of the monopulse comparator is greatly simplified, since the sum channel is physically separated from the difference channel and the difference pattern is obtained by using a simple power combiner. The coaxial probe-excited five-element monopulse feed has been designed leveraging a square wave septum polarizer, \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{3}{c}{**Sum Channel**} \\ \hline
**Parameter** & **Directivity** & **Beamwidth** & **Axial Ratio** & **Side Lobe** \\  & & & **at Boresight** & **Level** \\ \hline Value & 36.1–36.7 dBc & 2.50–2.80 deg. & 0.65 dB & \(-\)21 dB \\ \hline Parameter & Peak Cross & Return & Port & \\  & Pol. Directivity & Loss & Isolation & \\ \hline Value & 15.5 dBc & \(-\)15 dB & 12.5 dB & \\ \hline \multicolumn{3}{c}{Difference Channel} \\ \hline Parameter & Directivity & \begin{tabular}{c} Crossover \\ Angle \\ \end{tabular} & \begin{tabular}{c} Boresight \\ Directivity \\ \end{tabular} & \begin{tabular}{c} Side Lobe \\ Level \\ \end{tabular} \\ \hline Value & 32.6–32.9 dBi & 1.56–1.66 deg. & \(-\)15 dBi & \(-\)18 dB \\ \hline Parameter & \
\begin{tabular}{c} Peak Cross \\ Pol. Directivity \\ \end{tabular} &
\begin{tabular}{c} Return \\ Loss \\ \end{tabular} & \\ \hline Value & 22.0 dBi & \(-\)10 dB & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Performance of the proposed monopulse antenna at 14.5–16.0 GHz. Figure 21: 3D directivity patterns of the reflector at 14.5 GHz. (**a**) Sum pattern. (**b**) Azimuth difference pattern. Arrows mark the maximum and minimum values of the directivity. which responds to circular polarization, and two open-ended linearly polarized rectangular waveguides have been combined to achieve linear polarization for azimuth and elevation difference channels. The proposed feed has been used to optimally illuminate the reflector with a 10 dB taper angle of 75.4\({}^{\circ}\). At 14.5-16.0 GHz, the sum channel has a 36.1-36.7 dBc gain, 2.50-2.80\({}^{\circ}\) beamwidth, \(-\)21 dB sidelobe level, 0.65 dB boresight axial ratio, and 15.5 dBc peak cross-polarization directivity. At the same frequency range, the difference channel has a 32.6-32.9 dBi gain, \(-\)15 dBi boresight directivity, 1.56-1.66\({}^{\circ}\) crossover angle, \(-\)18 dB sidelobe level, and 22.0 dBi peak cross-polarization directivity. Conceptualization: A.M.M., C.-S.L. and J.-H.A. Methodology: A.M.M., C.-S.L. and J.-H.A. Validation: D.O. and B.-C.A. Formal analysis: A.M.M., C.-S.L. and J.-H.A. Formal data curation: D.O. and B.-C.A. Writing--original draft: A.M.M. Writing--review and editing: A.M.M., C.-S.L. and J.-H.A. All authors have read and agreed to the published version of the manuscript. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (grant number: NRF-2020R1I1A1A01066637). This work is the result of a study on the \"Leaders in Industry-university Cooperation 3.0\" Project, supported by the Ministry of Education and National Research Foundation of Korea. Not applicable. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (grant number: NRF-2020R1I1A1A01066637). This work is the result of a study on the \"Leaders in Industry-university Cooperation 3.0\" Project, supported by the Ministry of Education and National Research Foundation of Korea. Not applicable. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (grant number: NRF-2020R1I1A1A01066637).