Mosaic Frequency Selective Surface with Wideband Response for the Optically Transparent and Absorber Applications

This study investigated the performance of a Mosaic Frequency Selective Surface (MFSS) structure for two different applications: optical transparency and absorber. The MFSS for optical transparency application is comprised of a polycarbonate substrate with permittivity,
$\varepsilon_{r}$
of 2.9, and the MFSS for absorber application utilized a Polyethylene Terephthalate (PET) substrate with
$\varepsilon_{r}$
of 2.7. The MFSS unit cell is composed of a conductive metallic element design that integrates the Koch fractal and the double hexagonal loop for the optical transparency application. Meanwhile, the resistive MFSS unit cell with sheet resistivity of
$100\ \Omega/\text{sq}$
is utilized for the absorber application. A Computer Simulation Technology (CST) Microwave Studio software is employed to carry out the calculation and frequency response analysis for both applications. Based on the results, it was concluded that the transparent MFSS yielded a wideband stopband and passband responses (fractional bandwidth
$(\text{FBW}) > 50\%$
) with a low cross-polarization (−37 dB), and a wideband absorptivity response was achieved with thin MFSS absorber. In addition, the simulated and measured responses of the transparent MFSS achieved well-fitted correlations. The findings indicated that the proposed MFSS unit cell able to provide wideband response for both applications.