###### Abstract
Properties such as space filling, self- similarity, fractional dimensions, infinite complexity, mechanical simplicity and robustness make the fractal antenna unique to attain advantages such as miniaturization, wideband and multiband characteristics with better efficiency. The space filling property is used to reduce the antenna size and self-similarity to achieve the multiband resonant antenna. The number of iterations of these geometries is based on operating wavelengths. Although fractal antennas minimize size and cost, in the case of the communication system, many applications require many different frequency bands. Therefore, a single fractal antenna cannot serve the function of the entire communication system. To improve spectrum sharing and expand operational frequency ranges, one is likely to consider reconfigurable radio frequency (RF) circuits and devices. The current reconfigurable antennas for mobile terminals integrate different active devices for fine tuning their operation frequencies [11; 12]. This antenna offers compact size structures and improved gain and radiation patterns compared to conventional antennas. The resonating frequency, operating bandwidth and directivity of such antennas can be manipulated by introducing RF switches [13]. Based on the requirement on the reconfiguration property of the antenna, there are four major types of reconfiguration techniques, electrical, optical, mechanical and material [14; 15]. The reconfiguration techniques are presented in Figure 1. Existing reconfiguration solutions for RF switches are based on positive-intrinsic-negative (PIN) diodes [16; 17], microelectromechanical systems (MEMS) switches [18], varactor diodes [19], lumped elements [20], tunable materials [21; 22], or optical switches [23]. Depending on the ON and OFF conditions, these devices change the structure (length) of the radiating element. PIN diodes are mainly used in switching on and off certain parts of the antenna, and hence achieve frequency reconfigurability. [PERSON] et al. have proposed an electrically controllable rectangular microstrip patch antenna, which offers frequency reconfigurability using PIN diodes [24]. In the design, PIN diodes are incorporated to provide necessary electrical connectivity between the main radiator and the parasitic patches. The antenna offers frequency reconfigurability over a frequency range of \(\sim\)1.0 GHz with seven different frequency bands and constant radiation characteristics at all the reconfigured frequencies. PIN diodes present good performances at frequencies up to 20 GHz and are similar to field-effect transistor (FETs) devices, however, with the cost of high power consumption. [PERSON] et al. have demonstrated novel shaped hexa-band frequency-reconfigurable antenna with a very wide tuning band [25]. The proposed antenna operates at two single and dual band modes depending upon the switching states. For the numerical study, lumped components are employed to generate tunable capacitance, which is responsible for frequency reconfigurability. The fabricated antenna has wide tuning capability, which spans from 2.1 to 5.2 GHz. [PERSON] et al. presented a reconfigurable microstrip patch antenna that is monolithically integrated with RF MEMS capacitors for tuning the resonant frequency [15]. The reconfigurability of the patch antenna is achieved by loading it with a coplanar waveguide (CPW) stub on which variable MEMS capacitors are inserted at periodic intervals. The surface micromachining technique is used to create MEMS capacitors, which consist of a 1 \(\upmu\)m thick aluminum structural layer placed on a glass substrate, with a capacitive gap of 1.5 um. Low tuning values in the range of 0-11.9 V are used to electrostatically actuate MEMS capacitors. With 0 to 11.9 V actuation, the antenna resonant frequency can be continuously shifted from 16.05 GHz down to 15.75 GHz. However, the MEMS-based systems have a low tuning speed and need complex integration.