# Flexible Phased Antenna Arrays: A Review
## 6 Conclusions and Future Trends  
This paper analyzed several critical aspects related to the design and development of FPAs. An overview was provided of the most commonly used materials and technologies, as well as the major limitations currently encountered in their implementation.  
A first key direction explored involves the use of flexible substrates and AM techniques, such as IP, to realize conductive elements. While this approach is widespread, it typically enables only passive array configurations due to the inherent difficulty in implementing multilayer structures (integrating both conductive and dielectric layers). These multilayers are essential for embedding the control and RF electronics required in active array systems.  
Currently, the AME platform Dragonfly by Nanodimensions is the only one that supports 3D-printed multilayer architectures of both conductive and dielectric materials. However, they are limited by the narrow range of compatible dielectric materials and the lack of robust evidence supporting their integration with standard soldering processes which remain fundamental for high-performance RF systems.  
From a manufacturing point of view, a promising alternative lies in the use of rigid-flex PCB technologies. These offer a trade-off between structural flexibility and the reliability of conventional fabrication processes. This area is expected to witness significant developments in the near future, especially as the demand for conformal and adaptive antennas increases.  
Another key consideration is the impact of mechanical deformation on electromagnetic performance. The non-planar positioning of radiating elements in flexible arrays can degrade radiation characteristics. Addressing this issue likely requires the development of compensation techniques, such as phase correction and real-time electronic reconfiguration, to maintain optimal performance under deformation.  
Furthermore, the design of arrays based on unconventional geometries, such as concentric or concentric-hexagonal lattices, opens new opportunities for performance improvement, particularly in terms of SLL mitigation. However, these configurations pose new challenges for the design and implementation of complex feeding networks, which requires dedicated research efforts.  
In conclusion, the data presented in this review can serve as a starting point for identifying the target specifications for various application scenarios involving FPAs. They also provide a useful reference for guiding future research activities in this promising technology field.  
Conceptualization, F.P.C. and L.M.; methodology, W.U.U., F.P.C. and L.M.; formal analysis, W.U.U.; investigation, W.U.U.; data curation, W.U.U., F.P.C. and L.M.; writing--original draft preparation, W.U.U.; writing--review and editing, F.P.C. and L.M.; visualization, W.U.U., F.P.C. and L.M.; supervision, F.P.C. and L.M.; All authors have read and agreed to the published version of the manuscript.  
This research received no external funding  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflicts of interest.