Recent advances in microwave test equipment through the use of microwave sources
employing Direct Digital Synthesis (DDS) techniques enable frequencies up to 67GHz to be
achieved. When these are combined with state-of-the-art Vector Network Analyser (VNA)
receivers, new opportunities are opened up to develop current and voltage waveform
measurement systems, including active load-pull systems, that operate at very high
frequencies. The major technical hurdle that prevents this from being possible is the provision
of an accurate, wide-band phase reference which is required to convert a frequency domain
VNA into a time domain receiver capable of handling current and voltage waveforms.
Attempts have been made to solve this issue through the development of new types of phase
reference standards, however all of the approaches tried to date have been severely limited in
their frequency of operation. This research project would therefore look into the feasibility of
developing a new type of phase reference that is not frequency limited, but could in principle
be used to frequencies up to 67GHz and beyond.