Abstract
This paper reports on a tunable transmission frequency characteristics-based metamaterial absorber of an X band sensing application with a fractional bandwidth. Tunable resonator metamaterial absorbers fabricated with dielectric surface have been the subject of growing attention of late. Absorbers possess electromagnetic properties and range modification capacity, and they have yet to be studied in detail. The proposed microstructure resonator inspired absorber with triple fractional band absorption consists of two balanced symmetrical vertical patches at the outer periphery and a tiny drop hole at two edges. Experimental verification depicted two absorption bands with single negative (SNG) characteristics for two resonances, but double negative (DNG) for single resonance frequency. The mechanism of sensing and absorption was analyzed using the transmission line principle with useful parameter analysis. Cotton, a hygroscopic fiber with moisture content, was chosen to characterize the proposed absorber for the X band application. The electrical properties of the cotton changed depending on the moisture absorption level. The simulation and the measured absorption approximately justified the result; the simulated absorption was above 90% (at 10.62, 11.64, and 12.8 GHz), although the steady level was 80%. The moisture content of the cotton (at different levels from 0 to 32.13%) was simulated, and the transmission resonance frequency changed its point in two significant ranges. However, comparing the two adopted measurement method and algorithm applied to the S parameter showed a closer variation between the two resonances (11.64 and 12.8 GHz) which signified that a much more accurate measurement of the cotton dielectric constant was possible up to a moisture content of 16.1%. However, certain unwanted changes were noted at 8.4–8.9 GHz and 10.6–12.4 GHz. The proposed triple-band absorber has potential applications in the X band sensing of moisture in capsules or tablet bottles.
Highlights
This paper reports on a tunable transmission frequency characteristics-based metamaterial absorber of an X band sensing application with a fractional bandwidth
split-ring resonators (SRRs) loaded on a silicon substrate has been suggested for high strain tolerance, while resonance frequency shifting could be useful for sensing mechanical deformation[15]
Though the sample position changes during the experiment, it does not affect the capacitance of the intended resonance frequency range; a new metamaterial-based absorber is added to the resonator and the application to measure the moisture content in cotton slabs
Summary
This paper reports on a tunable transmission frequency characteristics-based metamaterial absorber of an X band sensing application with a fractional bandwidth. The samples considered in such research were one millimeter in size or more Thick dielectric materials such as FR4, wood, Rogers, and Taconic have been used for structure capacitive characteristics enhancement, as they modify the permittivity and permeability of the overall unit cell. Based on the structure of the unit cell resonator and material properties showed significant resonance frequency shifting This method of measuring necessitates covering up the entire structure by the sample, which is considered a substantial limitation because the sample quantity modifies the capacitance of the overall structure in the experiment. Though the sample position changes during the experiment, it does not affect the capacitance of the intended resonance frequency range; a new metamaterial-based absorber is added to the resonator and the application to measure the moisture content in cotton slabs. The high absorptivity was maintained by more than 90% (single resonance point), with a wide incident angle of up to 120° for both transverse electric (TE) and transverse magnetic (TM) for single resonance frequency
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