A compact miniaturized frequency selective surface (FSS) with stable resonant frequency is proposed in this letter. The proposed FSS is composed of four spiral triangles connected in the middle of the unit cell, symmetrically. Simulated results show that the dimension of the element is only 0.0558λ0 × 0.0558λ0, and reduction in FSS size is up to 97.7% with respect to conventional cross-dipole F...
