Millimeter waveband resonator method for absorption cross-section determination of vegetation stalks

A new millimeter wave resonant method for determination of absorption cross-section of vegetation stalks is given. The method is developed for study of vegetation stalks absorption cross-section as a function of their moisture content, or kR parameter (k is a wave number, R is a stalk radius) in millimeter wavelengths band. Modes E(01p) of a cylinder resonator are employed for such measurements. Dielectric permittivity and loss tangent of a sample can be found by measuring a frequency shift and Q-factor changes of the resonator. Absorption cross-section of a sample is then calculated using a formula obtained in our theoretical study. This formula can be written analytically as a result of rigorous solution of the related diffraction problem (scattering of a plane electromagnetic wave by cylinder with complex dielectric permittivity if stalk radius is less then 0.5 mm for the wavelength of 8 mm).