Thin film resonant metasurface absorbers using patch-based arrays on liquid crystal polymer substrates for centimeter-wave applications

This paper reports the design and development of thin-film resonant absorbers for narrowband and multiband operation in the frequency regions centered at 10 GHz. The structure of the resonant metasurface absorber (RMA) is based on a liquid crystal polymer (LCP) thin-film spacer with a copper patch array on the front surface and un-patterned copper film on the back surface of the LCP film. The design and simulation works were carried out using full-wave analysis of the RMA characteristics. The copper-based periodic patch array acts as a metasurface. The perfect RMA for a given LCP film thickness can be obtained through impedance optimization by adjustment of the dimensions of the lattice periods. The electric and magnetic field distributions were studied. The resonant film absorber based on a 100 μm thick LCP film has an electrical thickness of λ/300 at 10 GHz. The experimental work was conducted using a narrowband RMA prototype consisting of 11×11 cells. The measured result of the resonant absorption is at 10.1 GHz, which is in close agreement with the design frequency of 10 GHz. For multiband functionality, double- and quad-band film resonant absorbers have been designed based on a coplanar supercell utilizing the superposition of the resonance effect. The LCP film-based absorbers have the potential to be used in EM shielding and sensing applications in centimeter-wave applications.