To measure the insect body size parameters for Ku-band entomological radar

based on the insect data measured by a fully polarimetric measurement rig

the RCS (Radar Cross-Secion) characteristic of insects in Ku-band is studied. It is found that the scattering of the large insects is in the resonance region. Thus

the body size parameters of the large insect cannot be estimated from the RCS. To ensure the accuracy of body size measurement

it is necessary to identify and get rid of large insects. For this reason

a large insect discrimination method based on the relative phase of scattering eigenvalues and one of the RCS parameters is proposed. The relationships between insect body length and mass and RCS parameters for the middle and small insects are analyzed. It is found that all parameters can be well used for estimating the insect body length and mass

and the empirical formulas for insect body length and mass estimation are obtained.