Simulation, design and fabrication of microwave ferrite components for monostatic radar applications


Adams, Ryan Seamus.. (2007). Simulation, design and fabrication of microwave ferrite components for monostatic radar applications. Theses and Dissertations Collection, University of Idaho Library Digital Collections.

Simulation, design and fabrication of microwave ferrite components for monostatic radar applications
Adams, Ryan Seamus.
Microwave circuits--Design and construction Microwave circuits--Computer simulation Ferrites (Magnetic materials)--Industrial applications
Electrical Engineering
A theory encompassing ferrite materials and their application to microwave circuits is presented herein. Several aspects of these materials and the devices that incorporate them are discussed. In particular, the behavior of infinitely extended microwave ferrites in the presence of a radio frequency (rf) signal is reviewed. The conditions for Faraday rotation and birefringence are outlined and the electromagnetic wave response is quantified. Further, magnetostatic modes and spin waves are discussed which require that the rf electric intensity be identically zero.;A time-domain simulation routine is presented that accounts for electromagnetic wave propagation within finitely extended ferrite materials. This routine is fully second-order accurate. The routine is validated by comparing the network parameter data of a stripline phase shifter against the data obtained from a popular frequency domain formulation. Excellent correlation is observed, thus establishing that the routine is consistent with other simulation approaches.;A review of the Bode-Fano criterion is presented wherein the fundamental matchability of an arbitrary load impedance function is addressed. This criterion is represented by integral equations that provide a relationship between the bandwidth and tolerance of match of an arbitrary impedance function. This theory is applied to the matchability of three port circulators by appealing to the concept of a required load impedance for perfect isolation. When applied to circulators in this manner, the realized bandwidth can exceed the fundamental limit in certain cases, but it is shown that the Bode-Fano criterion still provides a good "rule of thumb" regarding the matchability of a given circulator device. Three circulators are presented in validation of the Bode-Fano criterion, each of which utilize ferrite materials that exhibit high crystalline anisotropy, and hence they are "self-biased" devices. Simulation data is provided for the frequency response of these circulators which demonstrate approximately 5% bandwidth centered around 23 GHz.;A unique circulator topology which consists of a rectangular ferrite region and orthogonal ports is presented. This topology arises from the theory of the perfect isolation impedance that allows for any arbitrary shape of the ferrite region and port locations. The Bode-Fano criterion is applied to this device and the achieved response correlates quite well the fundamental limits. In addition to this device, two circulator/antenna systems are presented which demonstrate that systems which incorporate circulators can be designed as a whole, rather than by designing individual components to some interface specification. Simulation and measured data are presented for each of these circulator devices and systems.;One additional antenna/circulator system is presented which accomplishes system design without the use of interconnecting matching networks; system design is accomplished by varying the circulator geometrical and material parameters. Once again, the Bode-Fano criterion is applied to this system with good correlation of the achieved response to the fundamental limit. Simulation data is presented as validation of this design approach.
Thesis (Ph. D., Electrical Engineering)--University of Idaho, July 2007.
Major Professor:
Jeffrey L. Young.
Defense Date:
July 2007.
Format Original:
xiv, 137 leaves :ill. ;29 cm.

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