Design of multilayer band-pass frequency selective surface based on filter circuit

The conventional design of the multilayer frequency selective surface (FSS) has the problem such as large calculation and time consuming. In this paper, a design method for the multilayer FSS is proposed based on filter theory and the equivalent circuit of FSS. Firstly, the equivalent circuit of multilayer FSS is synthesized by the filter theory, and then the circuit model is converted into the structure parameters of FSS by utilizing of equivalent circuit inversion method for FSS. It not only has the advantage of simple physical process, but also provides a rapid design process for precisely synthesizing the high order FSS with arbitrarily layers. In order to verify the accuracy of the proposed method, a K-band band-pass FSS radome with third-order is designed, and the radome prototype is fabricated and measured. The measured results show that the transmission characteristics agree very well with theoretical value calculated by filter theory. Moreover, the radome has less influence on the radiation pattern of antenna. It offers an accurate theoretical design method for synthesizing the multilayer FSS.