Microwave Multichannel Frequency Division Multiplexing by Defectives Star Waveguides

A multichannel frequency-division-multiplexing (FDM) system consisting of a one-dimensional photonic star waveguides (SWGs) structure is studied theoretically. This SWGs system exhibits large electromagnetic bandgaps that originate both from the periodicity of the system and the resonator's resonant modes that create zeros of transmission. The presence of resonator defects creates two defect modes (channels of filtering) in these large gaps. Our theoretical results show that a total transmission is observed for two Eigen frequencies (f(1) = 19.63 MHz and f(2) = 28.4 MHz) when the resonator defect length is four times the length of the undisturbed resonator. The associated quality factors reached 748 and 1132 for f(1) and f(2) respectively. A second time, another defect at the backbone level is added. The results of this research, show clearly that the backbone defect modes interact with resonators defect modes and give birth to the degeneration lifting. After this interaction, an energy transfer is obtained between the two frequencies propagating in the system. This enables us to obtain four defects modes with a very high performance when the length of backbone defect and resonator defect are suited to 2 and 1.93 m respectively.