**4. Conclusion**

As reconfigurable antenna is very useful nowadays in the similar manner including array technique makes it more applicable in many applications such as satellite communication, biomedical applications, radar systems, smart new generation systems such as 5G and beyond, etc. Graphene, comparatively very new material as per design of antenna in terahertz regime, is most required wonder material for reconfigurable array antenna. Apart from graphene, liquid crystal is also good material to design this antenna in gigahertz range. Also, there are so many other techniques to design and make it useful for various applications. Reconfigurable antennas play important roles in smart and adaptive systems and are the subject of many research studies. They offer several advantages such as multifunctional capabilities, minimized volume requirements, low front-end processing efforts, and good isolation; these makes them well suited to use in wireless applications such as fifth-generation (5G) mobile terminals. There are so many techniques available to reconfigure the antenna properties such as electrical, optical, mechanical, and material-based reconfiguration. Among all the options, material-based reconfigurable antennas are the simplest ones with excellent performance. Where liquid crystal is proved to be suitable candidate in microwave frequency range, the 2D material like graphene is proved to be a real gem in THz frequency range.


#### **Table 6.**

*Performance parameters of radiation pattern reconfigurable antenna.*


#### **Table 7.** *Performance parameters of frequency reconfigurable antenna.*

Frequency reconfiguration is explained and polarization reconfiguration is discussed with linear, right-hand circular, and left-hand circular polarization. Radiation pattern reconfiguration is also explained with beam variation range of 82°–115°. Efficiency of the proposed structure is slightly less because monolayer graphene has high surface resistance due to very high surface area to volume. But this issue can be eliminated by using multilayer graphene. Hence, graphene-based antennas offer better and simpler reconfiguration technique than any other existing technique at THz frequency.

#### **Figure 18.**

*2D polar plot of pattern reconfigurable antenna in orthogonal plane with different arrangements of patch elements.*

*Antenna Arrays - Applications to Modern Wireless and Space-Born Systems*
