Design of dual-polarised multiband frequency selective surfaces using fractal elements

A technique is proposed for the design of multiband frequency selective sur faces (FSSs) that is based on the use of fractal screen elements. The autho rs demonstrate the design methodology by exploiting the self-similarity of the crossbar fractal to implement a tri-band FSS. Another benefit of this d esign approach, in addition to its multiband performance, is that the frequ ency response of both the TE and TM modes are exactly the same, owing to th e symmetry in the tree-like fractal structure of the screen elements. Diele ctric loading effects have been considered for practical implementation of designs with coverage exceeding two bands. Finally, it is noted that the lo cations of the individual bands can be controlled by the scaling or similar ity factor used in the construction of the fractal screen elements.