# Worldwide Coverage Mobile Systems for
## 4 Ku-Band Antennas Design Techniques
### Planar Antennas
The single basic element consists of two novel loop elements combination which is interlaced to built the basic element to achieve the dual-band operation. The proposed approach shows an advantage: the response at transmission is nearly independent at both frequencies for the interlaced loop elements. The constructed three-layer dual-band element shows the performance that is summarized in Table 17. \begin{table}
\begin{tabular}{l c} \hline \hline
**Feature** & **Value** \\ \hline frequency band & Ku \\ gain & 8.98 dB \\ size & 44 \(\times\) 49 mm \\ substrate & Rogers Duroid 5880 \\ dielectric constant & 2.2 \\ structure & 16 elements (4 \(\times\) 4) planar array \\ average gain & 18 dB \\ side lobe level & below \(-\)20 dB \\ gain peak & 19.4 dB at 10 GHz \\ Vivaldi & high efficiency \\ \hline \hline \end{tabular}
\end{table} 
Table 15: Features of the Vivaldi antenna. In [31], an antenna that consists of a rectangular grating waveguide slot array is analysed. Furthermore, the paper introduces a design methodology for antenna aimed at application concerning satellite communications receivers. The antenna design targets a wide bandwidth in the Ku band for satellite communications. The radiating slots with a rectangular grating waveguide behave in the same way than a frequency-selective transmission line does and, at the same time, performs some additional filtering. Adjusting the rectangular grating waveguide parameters design parameters it is feasible to adjust/tune both the operating bandwidth and the out of band rejection. A prototype aimed at the \(Ku\) band was designed with eight-slot rectangular grating waveguide slot array antenna that serves to test the antenna and check the matching between the theoretical, simulation and measured features, and verify the proper performance. The main features of the proposed antenna are compared with those corresponding to a conventional eight-slot rectangular waveguide slot array antenna. The measurements taken on the antenna demonstrate that the antenna performance is appropriate to operate in the band between frequencies 12.25 GHz and 12.75 GHz. Table 18 show the main features of the proposed antenna as compared to the traditional one. The proposed antenna has a better out-of-band rejection performance. Furthermore, 14.8 to 21.3 dB additional realized gain suppression is achieved in the range 14.0-14.5 GHz when compared to the regular antenna, which is equivalent to an extra out of band filtering. Fabrication tolerance can produce milled metallic sheets provoking slight shape distortions that could result in high errors at some frequencies. A reconfigurable meta-surface beam-steerable reflector is proposed in [32]. The resulting antenna is aimed at satellite communications, where the whole Ku band would be covered. The design of the antenna is optimised to manage a 300 MHz bandwidth. The authors proposed a novel approach based on a new kind of electromagnetic bandgap element to construct the reflector where the change of the \begin{table}
\begin{tabular}{l c} \hline \hline
**Feature** & **Value** \\ \hline bandwidth & 30\% (Ku band) \\ antenna efficiency & above 70\% \\ cross-polarization (on-axis) & better than 30 dB \\ Rx gain & 30 dBi (10.94 GHz–12.75 GHz) \\ ITU-580.6 & Tx band (13.75–14.5 GHz) \\ \hline \hline \end{tabular}
\end{table} 
Table 16: Features of the hat-feed based 0.8-m reflector antenna. \begin{table}
\begin{tabular}{l c} \hline \hline
**Feature** & **Value** \\ \hline operation band & Ku (12.5–14.25 GHz) \\ phase-range & 300\% \\ downlink peak gain & 30.2 dBi \\ insertion losses & \textless{}2 dB \\ uplink peak gain & 32.3 dBi \\ aperture efficiency in downlink & 38\% \\ aperture efficiency in uplink & 46\% \\ \hline \hline \end{tabular}
\end{table} 
Table 17: Features of the three-layer dual-band and dual-polarized antenna.