# Worldwide Coverage Mobile Systems for
## 4 Ku-Band Antennas Design Techniques
### Planar Antennas
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Feature** & **Proposed Antenna** & **Conventional Antenna** \\ \hline antenna efficiency & 68.3–88.8\% & 66.9–84.6\% \\ \(-\)15 dB bandwidth & 6.4\% (12.03–12.83 GHz) & 6.0\% (12.05–12.80 GHz) \\
12.25–12.75 GHz performance & good & good \\ reflection coefficients (Tx) & \(-\)0.80 dB & \(-\)1.93 dB \\ gain peak (Rx) & 15.82 dBi & 16.36 dBi \\ measured realized gain (Tx) & \(-\)10.77 to \(-\)22.16 dBi & 4.07 to \(-\)0.84 dBi \\ \hline \hline \end{tabular}
\end{table} 
Table 18: Features of the proposed antenna vs. conventional antenna. capacitance of the metasurface reflector of each unit is carried out by using varactors. In this way, it is feasible the spatial control of the reflected beam phase. Although this technique is well described in scientific publications, especially in the sub 6 Ghz band, there are few references concerning the application of this approach to reflectors designed for the X-band. It also feasibly applied this technique to higher band, e.g., the Ku band, leading to design where the unit cell size is smaller than lower bands. In such a case, it should be considered that the varactor size is comparable to the area of the metasurface unit cell. Consequently, noticeable absorption and scattering effects affect the signal. These issues are analysed and displacing the varactor to the opposite side of the proposed reflector seems to be an appropriate approach for mitigating the absorption and scattering. This solution does not affect the lumped elements structure that models the device. In consequence, it is conclude that the introduced approach leads to a low-cost solution of the voltage-controlled reflector surface for Ku-band. Furthermore, as result of the analysis, design, implementation, and test of the antenna, fabrication hints are remarked to achieve the expected features for the Ku band reflector showing a wide dynamic stirring range performance. The simulations conducted along the investigation demonstrate that the proposed approach exhibits a wide bandwidth for incident signal (on the surface of the reflector), both orthogonal and off-orthogonal. In [33], the authors propose a method for enhancing the antenna gain in the case of circularly polarized (CP) magneto-electric dipole antenna (MEDA). The antenna is designed to operate in the full Ku band. In order to feed the CP MED antenna, it is also designed and implemented a single-layer partially reflecting surface that is constructed on a substrate containing arrays of metal patches that are printed on both the top and bottom forms a Fabry-Perot resonator antenna. This investigation also took into consideration the impact of the symmetrical patch and analysed and compared the following types in order to compare and optimize the reflective phase property:  
* double printed circular,
* square,
* circular-ring,
* square-ring patches, and
* single printed circular patch. After comparing the result achieved with each type, the authors choose the circular patch one given the exhibited gentle reflective phase gradient, i.e., the final overall gain achieved by the CP MEDA is improved in the whole addressed frequency band. The authors optimized and implemented a prototype, and measured the main features of the antenna to verify the theoretical and simulation results, obtaining the results shown in Table 19. The conclusion is that the introduced method seems to be an appropriate choice to implement satellite communication wide CP bandwidth antennas. In [34], the authors introduce the design and analysis of a circularly polarized dielectric resonator antenna (DRA) suitable to satellite communications. The designed antenna shows a wide bandwidth and, at the same time, low axial ratio values. The dielectric resonator antenna is the basic element used to compose the overall antenna, which is constructed by stacking several DRA. The antenna is finally fed at the bottom of the stack by a substrate integrated waveguide coupling slot. Low permitivity