In this paper we apply and discuss a method for the determination of the magnetic field ( H ) evolution in supernova remnants ( SNRs ) from radio luminosity at given frequency \nu to diameter ( L _ { \mathrm { \nu } } - D ) correlation .
We assumed that H evolves as H \propto D ^ { - \delta } , where D is the diameter of the remnant .
Value \delta \approx 1.2 is obtained under the equipartition assumption from the equations for revised equipartition calculation ( REC ) and by using the data sample from the nearby starburst galaxy M82 .
We try to investigate whether or not SNRs in M82 are in the equipartition state .
This is done by comparison of our empirically obtained \delta with the theoretical value expected for the equipartition conditions .
Inconsistence between the value obtained for equipartition conditions and adiabatic expansion ( \delta = 1.5 ) and the value empirically obtained herein , can be explained mainly by the influence of sensitivity selection effects which tend to flatten the slope of the L _ { \nu } - D relations for extragalactic samples .