Filters

Evanescent filters (meaning in waveguide below its cutoff frequency) are a useful way to get reasonably narrow band high-Q bandpass units. Here are some designs for 3.4, 5.76 and 10GHz all using short lengths of standard waveguide sizes. File:EVANFILT.pdf

AADE Filter design is a pretty good package for lumped element designs. Available from here : http://www.ke5fx.com/aadeflt.htm

Dom F1FRV has an excellent design sheet for coaxial stepped element low pass filters including end corrections. The site is in French, but the spreadsheet is easy to follow. http://f1frv.free.fr/main3e_Filtres_LP.html