Animals were placed in Plexiglas containers divided into ten separate cages (6 cm x 6 cm x 17 cm long, arranged in two rows of five) keeping the animals parallel to the electric field, with their heads facing outwards most of the time.
Since the spread in SAR was mainly due to the cage position, rats were placed into the cages at random each day.
Measurement and calculation details
The incident power was monitored using an isotropic probe. Whole-body SAR was first estimated using the plane-wave formula of Durney et al.  and then determined by monitoring the temperature rise under far-field exposure to 900 MHzCW using fibreoptic sensors inserted at three locations into a rat gel phantom.
Durney CH et al.
An empirical formula for broad band SAR calculations of prolate spheriodal models of humans and animals
Research Center of France Télécom (CNET; Centre National d'Etudes des Télécommunication), France
Conseil Régional d'Aquitaine, France
Shirai T et al.
Lack of promoting effects of chronic exposure to 1.95-GHz W-CDMA signals for IMT-2000 cellular system on development of N-ethylnitrosourea-induced central nervous system tumors in F344 rats