AbstractAmbient dielectric measurements as functions of frequency in X‐band microwave region have been made on solid samples of polystyrene. Effects of temperature (−120 to +160°C) at three different frequencies have also been studied. The measurement technique applied based on short‐circuited waveguide method of Roberts and von Hippel modified by Dakin and Works for low loss and medium loss samples. Two different types of relaxations are identified originating from main chain motion, wagging, and rotational motions of pendent phenyl group. Intrinsic activation energy for polystyrene molecule, dipole moment per repeat unit, and the average apparent energy of a polystyrene molecule associated with its induced transient dipoles have also been calculated and the data so obtained are explained and compared with standard lite