## 4 Antennas and Antenna Related Technologies for Future Internet  
In the current section, we attempt a classification of antenna and antenna-related technologies, identifying, as a key driving force, the tendency of antennas to become more and more competent. Indeed, independent of how potent the given version of a radiator can be, there is, deterministically, the need for the newer prototype to excel and expand on every key performance indicator (KPI) used to describe the specific targeted use case or application [237]. An easy example, to advocate in favor of this point of view, is, of course, the quantitative evolution of the MIMO concept and relative implementation. To increase in competence, antenna link systems, focused on wireless communications, started as SISO to evolve to multi-element array formations. Indeed, this is verified by the quantitative MIMO evolution across the wireless communication generations (Generation, (max) Number of Digital Ports): (3, 1(No-MIMO==SISO)), (4, (2)4--legacy MIMO)), (5,16), (5,5,64--masive \begin{table}
\begin{tabular}{p{142.3 pt} p{142.3 pt} p{142.3 pt}} \hline \hline
**Application Area** & **Description** & **Key Benefits** \\ \hline Satellite Communications & DT models dynamically predict and optimize satellite-to-satellite and satellite-to-Earth links, accounting for variables like frequency bands and modulation schemes. & Improved connectivity, reduced packet error rates, and minimized latency. \\ \hline Autonomous Vehicles (AVs) & DT models guide AV navigation by learning from real-world driving conditions to improve safety and efficiency. & Enhanced traffic control, collision avoidance, and improved decision making in complex scenarios. \\ \hline Drone Delivery Systems (UAV Navigation) & DT models manage large-scale drone navigation in crowded urban environments and ensure robust communication despite spectrum congestion. & Improved air traffic management, reduced human error, and optimized delivery efficiency. \\ \hline Mobile Edge Computing & DT frameworks predict and improve data offloading, latency reduction, and performance in distributed networks. & Reduced failure rates and enhanced resource management. \\ \hline Network Security & DT frameworks secure communication systems by improving precoding schemes, mitigating pilot contamination, and enhancing robustness against attacks. & Enhanced security, improved transmission strategies, and energy-efficient communication. \\ \hline Hardware Development & DT-integrated simulators improve device design, incorporating machine learning for performance prediction. & Accelerated development cycles, cost reduction, and enhanced system reliability. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Digital twin applications. MIMO), (6, 256 g-MIMO). In the next table (Table 4), we present the historical series of events in a more compact way [238]. Thus, having verified, at least partially, the radiators' evolution towards multi-competent designs, we unfold our point of view on the classification of antennas and antenna-related technologies, as shown in Figure 12.  
While achieving multi-competent designs is the goal, there are challenges ahead that dictate the route of the path forward. The first bifurcation point takes place under the pressure of assets availability and whether performance or cost is the driving factor. In the term 'assets', we include factors like available area and volume size of the host, access to it, power supply availability and thermal dissipation ability, available technologies, and so on. In case performance is the determining force, the delivered system can become more complex and expensive. In this case, it is the technology level that