Inductively coupled triple layers of ultra-miniaturized frequency selective surface for L-band applications

A novel ultra-miniaturized frequency selective surface (FSS) based on a triple layer of the convoluted metallic strip is presented in this article. The interconnection of metallic convoluted strips in each layer to one another by PTH holes increases the electrical length of FSS and thus reduces the resonant frequency to 1.23 GHz and hence the unit cell is miniaturized. The proposed FSS realizes a wide stop band centered at 1.23 GHz with a -10 dB impedance bandwidth of 400 MHz. The size of the unit cell is 0.024 lambda(o) x 0.024 lambda(o), which is atleast 29% smaller than the similar literature works. To demonstrate the validity of design, the FSS of size 30 cm x 30 cm accommodating 2500 unit cells with a periodicity of 6 mm is fabricated, tested, and verified with the measurement result. The FSS provides a stable response up to the incident angle of 60 degrees for both transverse electric and transverse magnetic operating modes. Furthermore, the proposed FSS is polarization insensitive because of its rotational symmetry. The proposed FSS finds suitable for the applications of GPS, aircraft surveillance, astronomy and mobile services, and so on.