A Single Layer Miniaturized Band Stop Frequency Selective Surface with Oblique Stability

In this paper, a highly compact single-layer frequency selective surface (FSS) with improved oblique stability is proposed for GSM shielding. The FSS element consists of interconnected concentric squares in each quadrant. These are connected with each other through outer convoluted square. The perimeter of the closed loop is significantly enhanced to lower the resonating frequency. This configuration successfully realizes the miniaturized FSS with band stop response. The unit cell size of FSS is reduced to 0.036
$\lambda_{0}\mathrm{x} 0.036 \lambda_{0}$
at resonating frequency of 900 MHz. The elements of unit cells are placed in C4 rotational symmetry to provide the polarization independence. The proposed miniaturized FSS enables the angular insensitivity for both the transverse electric (TE) and transverse magnetic (TM) polarization. The FSS exhibits stable response, with no variation in resonating frequency for up to 83° of incident angle variation. The other salient features of this FSS are simple geometry and low thickness. The resonating phenomenon of the FSS is explained with the help of distribution of current and electric field.