Highly-selective miniaturized first-order low-profile dual-band frequency selective surface

A miniaturized low-profile first-order dual-band frequency selective surface (FSS) is presented. The proposed structure consists of two resonators layers separated by an ultra-thin dielectric. One layer is a 2D periodic array of a conventional Jerusalem Cross (JC) shaped unit element. The other layer is based on a hybrid of cross slot dipole bounded by a square loop wire slot. The FSS structure utilizes resonant elements and strong coupling between the layers to achieve a high-Q dual bandpass response, delivering the first operating band at a low frequency. The main advantages of the proposed FSS include miniaturized periodic dimensions of about λ
₀
/15, ultra-thin overall thickness (in the range of λ
₀
/200, where λ
₀
is the free space wavelength at the lowest band of operation), and highly selective bandpass response. A prototype, simultaneously operating at S and C bands is fabricated and tested using a standard free space measurement.