Table 6 A comparative study of proposed MTM with some recently published tunable MTMs.

⁵²

CoFeSi-based magnetic microwire biased with DC voltage

0.2 GHZ

S-band

1. 100 wires are used

2. Thickness of wire 33 µm

3. Shift of frequency is 0.5%

4. Tuned resonance frequency is around 3.5 GHz

⁵³

Mercury based toroidal resonator tuned by temperature change

7.2 MHz/°C

S-band

1. Resonance frequency shifts to low frequency with increasing temperature

2. Linear shift noticed within 0–30 °C

⁵⁴

Tunability based on coupling between two crossed split ring resonators arranged in different rotation angles

2.5 GHz

C-band

1. Dual band resonances within 5.5–8 GHz

2. 2.5 GHz variation obtained within rotation angle 30°–90°

⁵⁵

The potential difference between p-type GaAs and n-type GaAs over the unit cell controls the resonances

–

2–6 THz

1. Semiconductor-based metamaterial

2. Resonance frequencies and their magnitude are tuned by controlling free electrons concentration of unit cell

⁵⁶

Electrical tuning by varying gate voltage of CMOS compatible nanopillars based metamaterial

240 nm

–

1. Wavelength shifting obtained for voltage change from – 4 V to + 4 V

2. More than 40% differential reflection is experimentally observed

3. Phase modulation up to 270° is achieved by optimizing nanopillar heights

Proposed

Tunability based on changing the length of four metallic stubs extended from the center and placed between four symmetrical quartiles

110 MHz

1.12 GHz

3.1 GHz

C-band

X-band

Ku-band

1. Symmetrical split-ring resonators are used

2. Frequency shifts are more pronounced within 12–18 GHz and less within 4–8 GHz

3. Simultaneous change of four tuning stubs from 2.5 to 5 mm helps to adjust the resonance frequencies