PhDAlthough the Maxwell equations govern the propagation of EM waves
at all frequencies, the methods required to generate, direct, analyse
and detect radiation differ from band to band.
This thesis is concerned with the development and demonstration
of 'Quasi-optical' techniques for millimetre wavelengths, which
involve the propagation of Gaussian profiled beams a few wavelengths
across, and the realization of a general circuit approach to mm-wave
measurement.
Gaussian beam-mode analysis, which is used in later chapters to
understand propagation of quasi-optical beams, is reviewed in
chapter 1.
Chapter 2 outlines the design, manufacture and testing of
corrugated feed horns which generate fundamental Gaussian beam-modes.
The design and manufacture of lenses which control the spreading
of the beams and directional couplers which provide desirable signal
processing functions in quasi-optical circuits is discussed in
chapter 3. Chapter 4 traces the development of a Faraday isolator
which operates in free-space and can suppress unwanted reflections in
quasi-optical circuits. Chapter 5 discusses a reusable circuit board
upon which systems can be easily and quickly constructed. A null
reflectometer built using quasi-optical components is outlined in
chapter 6 and reflection measurements from lenses and horns
presented.
Chapter 7 describes a corrugated feed horn/lens antenna used in a
balloon-borne nw-wave cosmic background experiment. Finally, Chapter
8 demonstrates the use of quasi-optical components in a 115 GHz
receiver circuit
