Application of Magnetic Nanostructures to the Design of Microwave Circuits

The growing interest in integrated microwave devices for automotive and wireless communication demands new innovative concepts. Reducing device dimension by increasing bandwidth and operating frequency is a major challenge. This thesis presents the design of such devices using arrays of ferromagnetic nanowired substrate (MNWS) embedded in insulating templates of polycarbonate or alumina. Due to the magnetic character of the nanowires, reciprocal as well as non-reciprocal devices can be obtained that are tunable in frequency by applying external magnetic fields.
Circulators, isolators, phase shifters, inductors and leaky-wave antennas have been developed on MNWS. For their design, the effective parameters of the composite material have to be known precisely. Therefore analytical models have been developed for determination of permittivity and permeability on MNWS, since these parameters are influenced by the ferromagnetic inclusions. Furthermore the fact that MNWS materials contain nanoscale zones five times smaller than their wavelength, places a severe limitation on the calculation capability of commercially available simulators regarding simulation time and convergence.
The accuracy of these models has been verified by transmission line measurements. A special focus has been given to the development of metamaterials on MNWS. In this thesis a single negative material, which has negative permeability, has been successfully measured on such a substrate for the first time.