The context of this project concerns microwave multiplexing for new architectures of RF systems for Electronic Warfare Applications. The main objective of this PhD study is to miniaturize some existing systems and reduce fabrication costs by proposing an alternative with better performances and able to be embedded in future airborne systems. RF/Microwave frequency multiplexing is typically used to split a wideband EM spectrum into different channels which number, width and contiguity obviously depend on the targeted application. The objective of this work is to prove the feasibility of planar contiguous 16-channels multiplexer over the 2-18GHz frequency range. Issues are to define the main architecture and to choose filters topology that fits with the strong electrical specifications. Moreover, the connection and tuning of the different filters need a particular focus in this study. Our proposal is based on an even/odd channels splitting that requires various microwave devices as Wilkinson power divider, diplexers and 4-channels multiplexers. The first device is quite well-known from Thales and has not been studied here. The two diplexers use filters with a new topology which synthesis is presented in this manuscript. These devices have been designed on a multilayered stripline substrate to achieve high couplings. Then, the two 4-channels HF multiplexers are based on the famous DBR topology that offers large design flexibilities and, finally, for LF multiplexers, which use wideband filters, interdigital and stubs topologies have been chosen. In addition, various CAD tools have been developed to facilitate the design of such complex circuits. It allows a high simplification of the design flow and, thus, a reduction of the tuning time. A lot of EM simulations have been performed before the fabrication of different prototypes to prove the concept and to exhibit good performances and a high miniaturization.
