School of Physics - Low-noise Oscillators and Frequency Standards

Lecturer: Dr. Eugene Ivanov

6 lectures module for honours students who want to specialise in radio physics, learn about noise in microwave devices and find out what limits the precision of frequency measurements. The course is based on the recent advances in the field of frequency stabilisation and noise measurements achieved by the scientists from the Gravitational Wave laboratory. These advances include the development of the microwave oscillator with phase noise 30 dB better than current state of the art, implementation of the new noise measurement technique allowing the thermal noise floor to be reached and development of the cryogenic "sapphire clock" with short term frequency stability better than 1.e-15.

If you want to work on developing the new radar systems or in telecommunication business, if you are interested in such problems as time keeping or testing the predictions of general relativity, you need a knowledge in the field of microwave oscillators.

Course structure

Properties of electromagnetic modes of whispering gallery in perfect crystals.
Simplified theory of loop oscillator. Concept of phase and amplitude noise in oscillators.
Phase noise reduction technique in oscillators (frequency locking)
Phase noise reduction technique in oscillators (phase locking)
Characterisation of oscillator frequency stability in time domain. Concept of Allan variance. Cryogenic secondary frequency standards ("sapphire clocks")
Atomic frequency standards. Using atomic clocks in fundamental physics experiments.

Practical session

During the one hour practical session in the laboratory students will be able to assemble a simple microwave loop oscillator and study its performance. They will also be introduced to basic experimental techniques used for the noise measurement. Finally, students will be able to experimentally study the operation and properties of the oscillator phase noise suppression system.