Design of a demultiplexer using slit-top mushroom-like electromagnetic band gap structures

This paper presents the three channels demultiplexer using the slit-top mushroom-like on two-layer structure of electromagnetic band gap (EBG) and transmission line. The challenge is to design an EBG structure providing variety of bandwidths of the multi-bandpass filter. The proposed structure of filter in this paper is composed of the four units of slit-top mushroom-like EBG, which are cascaded to yield the multi-bandpass characteristic. The differences of dimension and number of slit-tops truncating on the surface of mushroom-like EBG units that influence to the resonant frequency and bandwidth of filter have been shown and compared to the conventional mushroom-like EBG unit. Afterwards, the appropriate slit-top on the classical mushroom-like patches of EBG structure has been considered for the proposed multi-bandpass filter and diplexer. This work is the feasibility study of the multi-bandpass filter and the diplexer design by using EBG technology which can be modified to the microwave demultiplexer. Finally, the simulated and measured results for transmission characteristics, S21, are investigated to be in good agreement.