###### Abstract  
The proposed reconfigurable radiating antenna design is based on the integration of a reconfigurable fractal antenna and electro-optic substrate material. This antenna can be adjusted to achieve either re-configurability or tunability in the desired frequency range for wireless systems. The electromagnetic characteristics of the fractal antenna are manipulated at both the level of fractal geometry, electrical length and dielectric substrate. The designed antenna features multiband responses, in which the geometry and length change create a large frequency shift and the dielectric change using polymer dispersed liquid crystal (PDLC) creates fine and/or continuous tuning. The far field and scattering properties of the antenna are analyzed using the Computer Simulation Technology (CST) Microwave Studio Suite. The proposed approach has successfully demonstrated reconfigurable switching for up to four frequency bands between 0.2 and 0.6 THz. The dielectric constant change in the PDLC substrate shows fine and continuous frequency tuning with an 8% maximum frequency shift when operating around 0.54 THz and a high directivity of 7.35 dBi at 0.54 THz and 8.43 dBi at 0.504 THz. The antenna can also realize a peak gain of 4.29 dBi at 0.504 THz in the extraordinary polarization state of PDLC. The designed antenna can be readily integrated in the current communication devices, such as satellites, smart phones, laptops, and other portable electronic devices, due to its compact geometry and IC compatible design. In satellite applications, the proposed antenna can play a significant role in terms of security. The antenna could be extremely useful for satellites that want to keep their information secret; by constantly switching their operating frequency, spy satellites can evade detection and data collection from enemy ears. Hilbert fractal; reconfigurable antenna; frequency tuning; polymer dispersion liquid crystal 202213964 12.34.  
the system's dimensions. Conversely, ultra-wideband (UWB) antennas can be utilized to attain a wide frequency range (3.1-10.6 GHz) [4]. However, employing UWB antennas has several drawbacks, such as interference and coexistence with other radios. To avoid these problems, the concept of reconfigurability has considerably evolved. The antenna size has been greatly decreased thanks to frequency reconfigurability [5], making them suitable for use in any small handheld device. Instead of using multiple antennas that operate at different frequencies for signal transmission or reception, a frequency reconfigurable antenna is likely the most feasible solution for switching its operation to the desired frequency. There are three other categories of reconfigurable antennas, which include pattern reconfigurable antennas [6; 7], polarization reconfigurable antennas [8] and compound reconfigurable antennas [9], based on the operational antenna parameter that is dynamically adjusted. Reconfigurable antennas with varied fractal designs can be used effectively for applications in a wide range of frequency bands. Depending on the number of switches, two or more reconfigurabilities can be implemented at the same time. The cognitive radio system, in which an antenna adjusts to the appropriate frequency based on the available spectrum, represents the near future of wireless communication [10]. Accordingly, reconfigurable antennas, which are utilized in satellite communications and radar systems, are one of the best choices for such adaptive systems. To solve single or dual frequency band operation problems, a multiband antenna can be used where a single antenna can operate at many frequency bands. Applying a fractal shape to antenna design is one technique to make a multiband antenna. Fractal technology allowed for the designing of miniature antennas and integrating multiple bands into a single device.