I came across this while learning more about Fourier analysis and thought it might a hidden gem, and less the article is less than a year old (Dec. 2011).
The last section on ferrite loaded cavities, for variable resonance, especially caught my eye.
If the attachment does come through, here's the source link: http://www.adams-institute.ac.uk/resources/graduate_lectures/ted_wilson/Lect...
:-) neil KE6DCJ