PROJECT TITLE :

Terahertz Two-Layer Frequency Selective Surfaces With Improved Transmission Characteristics

ABSTRACT:

In this paper, a cascaded configuration for 2-layer frequency selective surfaces (FSSs) at terahertz (THz) frequencies with improved filtering characteristics is realized for electrically thick substrates. At THz frequencies, the thicknesses of commercially on the market substrates are admire the free-area wavelength. Consequently, the substrate plays a vital role in determining the transmission characteristics of THz multilayer FSS structures. Correct coupling method between FSS structures should be chosen to avoid unwanted substrate resonances or Fabry–Pérot resonances, which otherwise degrade the transmission characteristics of the cascaded FSS structure. During this paper, a cascaded structure to avoid multiple reflections among the substrate is presented and the same is used to appreciate 2 double-layered FSS structures to boost the transmission response. The transmission response is improved by introducing an additional transmission zero at a frequency location lower than the resonant frequency, thereby achieving high roll-off rate for the lower aspect of the stop band, and to suppress unwanted resonances, thereby increasing the rejection bandwidth of the filter. The proposed cascaded FSS structures were fabricated and tested using THz time-domain spectroscopy. Smart agreement between simulations and experiments were obtained.