# A Review of Multifunctional Antenna Designs for Internet of Things
## 3 Conclusions  
This report has provided a comprehensive overview of various antenna designs, tailored to meet the diverse requirements of the Internet of Things (IoT). We categorized these antennas based on their suitability for different IoT applications, highlighting the evolution and specialization within the field.  
In biomedical applications, including in-body monitoring and actuation, the focus has been on developing compact and efficient antennas that can be implanted or encapsulated. Electrically small antennas with meandered or loop structures have become prevalent due to their favorable size and performance characteristics. More recently, there has been growing interest in magnetoelectric antennas, which offer unique advantages in terms of miniaturization and efficiency at lower frequencies. However, their adoption has been limited by poor radiation characteristics and sensitivity to vibrations.  
In the context of smart homes, all-polarization antennas with frequency agility have been identified as promising solutions for enhancing the connectivity of household appliances. The tunability of these antennas can be achieved through various means, including nonlinear electrical elements like PIN diodes and varactors, as well as innovative materials such as liquid metal. However, the latter is not yet suitable for integrated devices.  
For smart city applications, pattern-reconfigurable antennas are highlighted for their ability to provide high gain and support space-division multiple access, which is essential for efficient data traffic management between the multiple IoT sensors and actuators in metropolitan areas. Despite advancements, achieving electronically controlled continuous steering of the antenna's beam poses significant design challenges, with beam-switching methods remaining the most commonly explored technique in the literature.  
As the field of antennas continues to evolve, the drive toward multifunctional designs is becoming increasingly important for commercial use as the era of the IoT rapidly approaches. Industries demand antennas that can accommodate the specific needs of various applications--from biomedical devices to smart home systems--creating an overwhelming need for innovative solutions. This pursuit of multifunctionality not only challenges traditional antenna concepts but also opens up new avenues for research and development of novel designs. To fully achieve these targets, it is essential to foster synergy between engineers and non-engineers. Collaborative efforts with experts in fields such as biology, healthcare, urban planning, and user experience design are crucial to ensure that antenna designs are not only technically sound but also aligned with the practical and social needs of users. By integrating diverse perspectives and expertise, the development of IoT antennas can better address real-world challenges and enhance the functionality and adaptability of IoT systems.  
Conceptualization, G.K. and M.T.C.; methodology, D.G.A.; validation T.M.E.; formal analysis, D.G.A. and T.N.F.K.; investigation, D.G.A., T.N.F.K. and T.M.E.; resources, D.G.A.; data curation, M.T.C.; writing--original draft preparation, D.G.A. and T.M.E.; writing--review and editing, D.G.A., G.K. and M.T.C.; visualization, D.G.A. and M.T.C.; supervision, G.K. and M.T.C. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The authors declare no conflict of interest.