The only accurate way to measure loop inductance for an installation is
to use an inductance meter. Calculations do not take into account the
loop environment like trees and other objects in the vicinity. The same
applies to natural resonant frequency, the loop or any other antenna
needs to be measured in situ, calculations for real situations can be
totally different from theoritical values.
This is where a lot are going wrong on LF. The theoritical and practical
results including power measurements are often totally wrong when
calculated as opposed to being measured in the field.
73 de Mal/G3KEV