## 1 Introduction  
A metamaterial is a non-natural material structure that possesses rare material properties, such as negative permittivity, negative permeability, reverse doppler effect, and negative refractive index, known as metamaterial (MTM) properties [1]. MTM properties depend on the geometry of the unit cell structure with a stable structural composition. These extraordinary physical properties make MTMs appropriate for numerous applications, such as sensing [2, 3], imaging [4], metamaterial coding [5], lensing [6], reflect arrays [7], terahertz applications [8], invisible clocks [9], antennae [10, 11, 12], absorbers [13], programable analog differentiators [14], etc. The perfect or near-perfect metamaterial absorber has the ability to absorb a specific frequency by preventing reflection and transmission of electromagnetic (EM) waves at a given frequency [15, 16, 17, 18, 19]. MTMs have attracted significant attention due to their extensive potential application areas, such as imaging, optical switching, energy harvesting, bolometry, radar cross-sectioning, antenna side-lobe reduction, SAR reduction, solar cells, sensing, etc. [20; 21; 22; 23]. Therefore, MMAs can replace traditional absorbers, such as wedge-shaped, Salisbury screen, Jauman layer, and ferrite absorbers due to their bulkiness and thickness, although limited to a few applications [24]. The main benefit of MMAs over traditional absorbers is their ease of fabrication, low cost, lightweight, ultra-thin thickness, and near-unity absorption [25]. Most MMAs consists of a three-layer sandwich model (metal lossy substrate-metal) [26]. In MMAs, near-unity absorption peaks are achieved by controlling the imaginary and real part of complex dielectric, magnetic permeability and electrical permittivity. The input impedance of MMAs matches with free space impedance, which is achieved through specific geometrical design of the top metal (resonator) [27]. Impedance matching between air and the MMA reduces the reflected power at a particular frequency, and the bottom metal blocks EM wave transmission through the MMA [28]. The major limitations of the resonator base of MMAs are the narrow low values of the absorption band, which reduce the operating range and accuracy of the MMA. This limitation can be overcome by multi-band MMAs, which have an increased operating range and efficiency [14; 29; 30; 31]. Multiband perfect absorption with full programmability of the absorbed bands was demonstrated in [14] by in situ tuning of an overmoded scattering system equipped with a programmable metasurface to the desired functionality. Moreover, polarization-insensitive behavior is also an important feature of MMAs, resulting in stable absorption properties at different polarization angles, which improves the usability of MMAs at different polarization values [29; 32; 33]. MMAs have the potential used for sensing applications in the microwave range. Various devices have been proposed for different sensing applications, such as permittivity sensors, refractive index sensors, grin sensors, density sensors, temperature sensor, and glucose sensors [29; 30; 32; 33; 34; 35; 36; 37]. Moreover, K- and Ku-band frequencies can be applied for short-range microwave sensing [38; 32; 39]. Various metamaterial absorber is designed in the microwave (C, X, Ku, K) to the terahertz frequency band [40; 41; 42]. Ku and K band frequency has wide application in the radar, telecommunications, and sensor fields. A magnetic plasmon based metamaterial sensor has been designed in [43] for infrared wavelength, where the metamaterial was designed by Ag nanowire on Ag substrate. In [44], a splits ring resonator-based refractive index sensor is presented for protein sensing. A circular split-ring resonator (CSRR) metamaterial absorber was presented in [13] for K-band absorption and sensing applications, showing two 99.9% absorption peaks at 21.6 GHz and 24.04 GHz. The complete dimensions of the CSRR is 10 \(\times\) 10 \(\times\) 1.6 mm\({}^{3}\).