In this work, new types of microwave tunable devices, circuits and components based on substrate integrated waveguide (SIW) are presented. SIW technology can be considered as a synthesized planar form of rectangular waveguide, and inherits almost all of its properties. For example, similar to rectangular waveguide, SIW is lower in loss, it can be used for higher power applications compared to conventional planar counterparts, and it is lower in cost. Although SIW is similar to rectangular waveguide in many aspects, it holds a significant difference in terms of size. Rectangular waveguide is usually made of hollow metallic tube (rectangular or circular), therefore at a given frequency, its size is much larger than the conventional planar transmission lines (microstrip or coplanar). Thus, even though rectangular waveguide being capable of delivering outstanding RF performance cannot be directly used in realizing compact planar circuits. Since SIW technology inherits almost all the properties of rectangular waveguide and also it is planar in nature, it is an outstanding candidate in realizing microwave and millimeter wave planar integrated circuits. However, SIW is usually fabricated on dielectric substrate, thus its power handling capabilities and its performance in terms of losses are largely dependent upon substrate material used and structure topology.;In this work, SIW-based microwave tunable devices, circuits and components using ferromagnetic materials are presented. Ferrites or ferromagnetic material permeability value can be controlled through the application of an external DC magnetic bias. Since the propagation constant of an RF signal is directly proportional to the square root of the material permittivity and permeability. Therefore, any change in the permeability component also changes the propagation constant of the electromagnetic wave. Thus, using ferrite materials allow the realization of very interesting reconfigurable devices. Another important characteristic of ferrite materials is that they display non-reciprocal behaviour. This means that RF signals, propagating in two different directions in the ferrite material can have different characteristic behaviours. This is a very interesting feature, which can be used not only to realize tunable microwave devices, but also devices that are non-reciprocal in nature. Some of the ferrite-based non-reciprocal devices include isolator, gyrator, and circulator. In literature, it can be observed that most of the nonreciprocal and tunable devices using ferrite materials are designed based on rectangular waveguide technology. The low loss and high power handling property of rectangular waveguide make them an attractive candidate in realizing ferrite based tunable devices. Moreover, for a rectangular waveguide operating with dominant TE10 mode, the maximum magnitude of its electric field occurs at the central region, whereas the maximum magnitude of its magnetic field occurs along the sidewalls. This distribution of electric and magnetic fields, allows placing the ferrite materials in the regions of the highest magnetic field without perturbing the electric field distribution. Since the ferrite materials interact strongly with magnetic field, they are usually placed in the regions where the magnetic field concentration is highest. Although rectangular waveguide is a very promising technology in realizing high power magnetically tunable devices, they cannot be readily integrated in a planar form. Therefore, one of the purposes of this thesis is to realize SIW based magnetically tunable ferrite loaded microwave devices that are planar in nature and at the same time retain all the good qualities offered by the rectangular waveguide.;In this work, key microwave magnetically tunable devices, circuits and components including resonator, band pass filter, oscillator, switch, phase shifter, circulator, and power amplifier are presented. It is also demonstrated that using only ferrite materials, the device total tuning range and performance are limited. However, by combining an innovative simultaneous electric tuning with the magnetic tuning, the total tuning range can be significantly extended, and also the circuit performance can be improved. Therefore, in this work, a new concept of two-dimensional tuning (simultaneous electric and magnetic tuning) is also introduced and demonstrated. This concept is then used to realize fully-adaptable and reconfigurable band pass filter, resonator and antenna. Special features of the proposed two-dimensional parameter tuning are revealed and discussed.
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