Ultra Low Noise Microwave Dielectric Oscillators at 3.8GHz and 10GHz and High Q Tunable Bragg Resonators

The thesis is divided into three parts. The first part of the thesis describes the design and development of two prototypes of an ultra-low phase noise 3.8GHz dielectric resonator oscillator. The first prototype included vibration measurements with a reasonable phase noise measurements developed for Selex-ES. The phase noise for the first 3.8GHz oscillator is -117 dBc/Hz at 1kHz offset and -150 dBc/Hz at 10kHz offset. The second prototype was the improved modular yet compact oscillator was then developed which demonstrated a significantly improved phase noise performance of -125.6 dBc/Hz at 1kHz offset and -153 dBc/Hz at 10kHz offset which is the lowest noise reported in the literature in this frequency band using a ceramic dielectric resonator. In the second part of the thesis, a design and measurement of a high Q broad tuning aperiodic Bragg resonator operating at 10GHz is described. The resonator utilises an aperiodic arrangement of non (λg/4) low loss alumina plates (ℰr=9.75, loss tangent of ~1 to 2 ×10-5) mounted in a cylindrical metal waveguide. The insertion loss, S21, varied from -3.9 dB to -6.4 dB while the unloaded Q varies from 81,650 to 61,020 over the tuning range of 100MHz (1%). In the third part of the thesis, simulation, design and measurement of a low noise Bragg resonator oscillator operating at 10GHz is presented. The oscillators demonstrated a phase noise of -153 dBc/Hz at 10kHz offset and -123 dBc/Hz at 1kHz offset for an unloaded Q of 190,000. To achieve these results extensive optimization of different transistors with different power level and noise figure has taken place