# Radiator Enablers for Wireless Communication Evolution
## 3 Radiators' Novel Technologies, Design, and Implementation Issues
### Advanced Antenna Designs in the mmWave Frequencies  
#### 3.5.1 General Description  
mmWaves are employed for use in 5G and 6G since, with higher frequencies, a much larger bandwidth becomes available, allowing for higher transmission rates. Additionally, mmWaves are more directional, meaning that the beam and information signal can be targeted and confined only where it needs to be. Communication becomes more secure and consumes less power. Furthermore, there is a reduced possibility of electromagnetic interference since each communication is carried out in a targeted manner.  
The use of these frequencies for the next generations of wireless communication, although necessary, nevertheless presents problems and challenges. First, some inherent phenomena are present, more specifically these frequency ranges exhibit increased losses in space, so there may be a distance limitation. Secondly, engineers must face and overcome various challenges in designing new transceivers, circuits, and antennas that must be manufactured and operate with high fidelity, inexpensively, to be available on time to penetrate the market. Indeed, the new generation of antennas must be compact yet efficient, with high gain and directivity, and capable of self-adjusting to the demands of the moment. The general classification of mmWave antennas is shown in Table 9 (refs. [92; 93; 94; 95; 96]).  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Design Technology: Antenna Type** & **Characteristic** & **Drawbacks** \\ \hline Dipole Antenna & easy to build & Low gain \\ \hline Loop Antenna & Easy to build & multi-element loop antennas are necessary for next generations \\ \hline \multirow{4}{*}{Horn} & Broad bandwidth, & \\  & low side-lobe levels, & \\  & large power handling, & \\  & basic design & \\ \hline \multirow{4}{*}{Reflector} & Enhanced gain and efficiency, & \\  & compact dimensions, & Costly \\  & enhanced emission directivity & \\ \hline \multirow{2}{*}{(Antipodal) Vivaldi Antenna} & High gain, & \\  & broad bandwidth & Needs extra space \\ \hline \multirow{2}{*}{Lens} & Broad bandwidth, & \\  & high beam focus & Large surface \\ \hline \multirow{2}{*}{Microstrip} & Compact design, economical, & Low power handling, \\  & microwave compatibility, & reduced radiative efficiency, \\  & low weight, easily manufactured & limited bandwidth \\ \hline \multirow{2}{*}{Magneto-Electric Dipole Antenna} & \multirow{2}{*}{Broad bandwidth} & Costly \\ \hline \multirow{4}{*}{On-Chip Integrated} & Advanced integration, & Low electrical impedance, reduced metal \\  & superior dependability, & conduction, enhanced \\ \cline{1-1}  & space-efficient design, & dielectric properties \\ \cline{1-1}  & cost-effective & \\ \hline \multirow{2}{*}{Fractal Antenna} & Reduced size of antenna, & \\ \cline{1-1}  & broad bandwidth & Difficult design \\ \hline \multirow{2}{*}{(Planar) Inverted F Antenna} & \multirow{2}{*}{Extremely low profile} & Low gain, \\ \cline{1-1}  & & limited bandwidth \\ \hline \hline \end{tabular}
\end{table}
Table 9: Main types of mmWave antennas.