No description available.

Thesis (PhD)--University of South Australia, 1997

[Truncated abstract] This thesis is split into two parts. In part one; A 50 K dual mode oscillator, the aim of the project was to build a 50 K precision oscillator with frequency stability on the order of 1014 from 1 to 100 seconds. A dual-mode temperature compensation technique was used that relied on a turning point in the frequency-temperature relationship of the difference frequency between two orthogonal whispering gallery modes in a single sapphire crystal. A cylindrical sapphire loaded copper cavity resonator was designed, modelled and built with a turning point in the difference frequency between an E-mode and H-mode pair at approximately 52.5 K . . . The frequencies and Q-factors of whispering spherical modes in the 3-12 GHz range in the fused silica resonator are measured at 6, 77 and 300 K and the Q-factor is used to determine the loss tangent at these temperatures. The frequency and Q-factor temperature dependence of the TM2,1,2 whispering gallery mode at 5.18 GHZ is used to characterise the loss tangent and relative permittivity of the fused silica from 4-300 K. Below 22 K the frequency-temperature dependence of the resonator was found to be consistent with the combined effects of the thermal properties of the dielectric and the influence of an unknown paramagnetic impurity, with a spin resonance frequency at about 138 ± 31 GHz. Below 8 K the loss tangent exhibited a 9th order power law temperature dependence, which may be explained by Raman scattering of Phonons from the paramagnetic impurity ions. A spherical Bragg reflector resonator made from multiple concentric dielectric layers loaded in a spherical cavity that enables confinement of field in the centre of the resonator is described. A set of simultaneous equations is derived that allow the calculation of the required dimensions and resonance frequency for such a resonator and the solution is confirmed using finite element analysis. A spherical Bragg reflector resonator is constructed using Teflon and free-space as the dielectric materials. A Q-factor of 22,000 at 13.87 GHz was measured and found to compare well with the design values.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaf 31). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 92-95).

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 146-148). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph.D.)--City University of Hong Kong, 2005. / "Submitted to Department of Mathematics in partial fulfillment of the requirements for the degree of Doctor of Philosophy" Includes bibliographical references (leaves 121-133)

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1971. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

A study of high frequency millimetre wave oscillators is performed operating at W- band and above, using test bench equipment designed and constructed in St. Andrews. Octave tuneable oscillators have been designed, constructed, and used to characterise developmental Gunn devices, as well as to provide ideal oscillators for test bench measurement systems. These oscillators have been sold to many millimetre-wave laboratories throughout Britain. The operation, optimisation and characterisation of these oscillators is described in detail, and various non-linear effects are explained and modelled successfully. The wideband tuneability and matching has also allowed evaluation of new developmental Gunn devices to accurately determine the optimum operating frequency range of the devices. This was part of a developmental program by GEC Hirst and MEDL which has now produced state of the art GaAs Gunn oscillators at 94GHz. Much of the characterisation of the oscillators is performed using novel quasi-optical techniques, which has allowed low loss accurate performance at these very high frequencies. Several quasi-optical techniques are described and the design, manufacture and evaluation of many optical components are given. In particular, the frequency and harmonic content of the oscillators was determined using a Martin-Puplett Interferometer which utilised a frequency counting technique. This enabled easy wideband measurements to be performed with much greater accuracy than traditional cavity wavemeters. In addition, a state of the art noise bench has been designed and constructed for operation at W -band and above, that utilises a novel open resonator to effect a very high Q suppression filter. The system has been shown to make noise measurements at much lower power levels and with greater sensitivity than comparable systems.