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Title: Transferred electron oscillators at mm wave frequencies and their characterisation using quasi-optical techniques.
Author: Smith, Graham M.
ISNI:       0000 0001 2449 8198
Awarding Body: University of St Andrews
Current Institution: University of St Andrews
Date of Award: 1990
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A study of high frequency millimetre wave oscillators is performed operating at Wband 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 dervices, 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 GEe 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 quasioptical 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 wavcmeters. 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.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Gunn devices; Circuit theory; Non-linear diodes Electric circuits Electronic circuits Solid state physics