A Miniaturized Triband Frequency Selective Surface Based on Convoluted Design

A novel miniaturized tri-band frequency selective surface (FSS) based on convoluted design has been proposed in this letter. The proposed FSS is a low-profile structure, and it is composed of two periodic metallic arrays separated by a thin dielectric substrate. The top metallic array is composed of four branched spiral triangles connected in the center, and the bottom one is consisting of gridded tortuous cross-dipole. The proposed FSS can provide three passbands operating at 3.28, 4.2, and 5.4 GHz, respectively. The unit cell is only 0.066 λ
₀
× 0.066 λ
₀
in size, where λ
₀
is the wavelength of the first resonant frequency in free space. In addition, the proposed FSS provides a stable performance under oblique incidence for both TE and TM polarizations. For verification, an FSS prototype has been fabricated and measured. Good agreements between the simulated and the measured results can be observed.