# Worldwide Coverage Mobile Systems for
## 4 Ku-Band Antennas Design Techniques
### Planar Antennas
\begin{table}
\begin{tabular}{l c} \hline \hline
**Feature** & **Value** \\ \hline frequency band & 12 GHz \\ structure & 16 linearly polarized dual-band elements \\ impedance bandwidth (at \(-\)10 dB) & from 7.8 GHz to beyond 8.5 GHz \\ axial ratio (at 3 dB, lower band -right-hand CP-) & 8.15-8.35 GHz \\ axial ratio (at 3 dB, higher band -left-hand CP-) & 14.2-14.8 GHz \\ \hline \hline \end{tabular}
\end{table} 
Table 14: Features of the microstrip array antenna. \begin{table}
\begin{tabular}{l c} \hline \hline
**Feature** & **Value** \\ \hline frequency band & 12 GHz \\ gain & 8.98 dB \\ directivity & 10.83 dB \\ efficiency & 83\% \\ bandwidth & about 693.6 MHZ (5.9\%) \\ structure & 2 \(\times\) 2 linear array \\ substrate & FR4 \\ thickness & 1.6 mm \\ dielectric constant & 4.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Features of the high gain patch antenna array. is mainly aimed at applications concerning synthetic aperture radar (SAR), in concrete, for small surveillance satellites. The antenna design introduces as novelty modifying the structure of the proposed antenna in order to achieve higher performance, i.e., improving the radiation pattern properties and electrical characteristics: directivity, gain, return losses (S11), voltage standing wave ratio (VSWR), impedance, and antenna efficiency. The methodology used to design the array antenna followed a standard procedure for similar designs. Formerly, a single antenna element is characterized, designed, and optimized. For this task, a genetic algorithm was used. Table 15 provides the main features of the Vivaldi antenna after optimization. The antenna structure optimization is aimed at improving the performance, i.e., the resolution capabilities, in applications concerning synthetic aperture radar. The simulation results are validated by the construction of a prototype and measurement of the main characteristics. It is concluded that the proposed antenna seems to be suitable for applications involving high-resolution synthetic aperture radar. A novel multi-segment rectangular dielectric resonator antenna is introduced in [28] for satellite communications. The proposed antenna is aimed at wide bandwidth operation, specifically for military and satellite applications in the frequency bands X and Ku. The approach that is introduced by the authors is based on an FR4 notched rectangular dielectric resonator antenna where a high permittivity insert of Alumina to improve the performance, and it is set into a segment of U-shaped Rogers 5880. A 50 \(\Omega\) Coaxial feeder exciting the setup is used to achieve a high gain across the whole aimed wide bandwidth. It is worthy to note that the proposed approach shows a wide impedance bandwidth (about 130%). The peak gain is measured at 11.2 GHz with a value of 8.5 dBi. The approach shows a radiation efficiency on average of 92.1% for the whole impedance bandwidth, with a radiation pattern omnidirectional in both axes. A hat-feed based 0.8-meter reflector antenna is proposed in [29]. The antenna is aimed at satellite communications in the Ku band, and specifically for mobile applications. The authors designed and simulated the antenna to analyse its performance. The antenna setup is composed by a Sub-1M ring focus reflector antenna, where a self-supporting dielectric hat-feed is added. The choice of the hat-feed element was based on the radiation pattern key properties: low side-lobe and low cross-polarization. To achieve the best performance, the authors studied and optimized the hat-feed in order to achieve a wide bandwidth operation. A prototype of the antenna was constructed and measured in the near-field after simulation to corroborate the results, which are shown in Table 16.  
In [30], it is analysed and designed, implemented and test a transmit array antenna with high-gain dual-band and dual-polarized. The antenna was designed to operate in satellite communications.