Nowhere that I can find in the standard or other literature is the proper length in lamdas (or aspect ratio) for a resonant waveguide cavity to make perturbation measurement. Plan to use option 300 material software but at 2.45 Ghz (wr340 wg) and 0.915 Ghz and not just 10. Also plan to make permeability measurements and there is even less information on resonator construction for that. Does the sample hole have to be centered on cavity through wider span of waveguide or off center through H wave max? I have seen both but no calculation to show where to drill. How low a Q can I get away with? 1000, 2000, 500? Saw 12 inch wr340 resonator at Agilent, but need to make 'proper' one.