PhD Defense of LUONG Duc Long

This work focuses on providing innovate solutions for designers in the realization of high-quality and compact passive devices in the RF and millimeter-wave bands. These devices are based on slow-wave microstrip lines on structured substrate, either on PCB with blind vias for RF applications, or on metallic nanowire membranes in the millimeter-wave range. This work was achieved in partnership with the University of Sao Paulo. The complete works include (i) topology analysis, (ii) the development of an equivalent model validated by electromagnetic simulations (HFSSTM) and measurements, (iii) design charts and (iv) applications on design of novel miniaturized passive devices. These transmission lines give the flexibility for designers and capability to be indifferently placed on structured substrate without any impact on their electrical parameters. A novel miniaturized hybrid coupler using this line is proposed, as a proof of concept. In the other hand, a comparable study on the structure of slow-wave coupled microstrip lines is developed. The principle of coupling on structured substrate is shown for their advantages and drawbacks and then an electrical model is also proposed in order to realize a miniaturized 0-dB forward-wave directional coupler using these lines. Moreover, an essential part of this thesis concerns the utilization of the slow-wave microstrip structure to miniaturize non-reciprocal passive devices: a novel microstrip isolator with the introduction of vias inside the ferrite and a novel design for a miniaturized circulator on a ferrite-dielectric substrate with blind vias have been proposed