The performance of GSM 900 antennas in the presence of people and phantoms

The antenna efficiency and mean effective gain (MEG) of several commercial (predominantly dual band) mobile phones are evaluated over the GSM 900 frequency range. Measurements are performed both statistically, in the presence of people, and with phantom heads and hands. Particular attention is given to the different loss terms involved, such as mismatch and spatial filtering, and to the relative contributions to loss of different parts of the body. The method used is that of 3D radiation pattern integration based on fast spherical near field measurements around the combination of the user and phone. Helical, "flip" and planar inverted-F antenna (PIFA) designs are evaluated. Results show that reasonable convergence is achieved with approximately 15 users. The average efficiency is in the 3-8% range for all phones when used next to the head. Measurements away from the head show that much of the efficiency reduction is due to loss in the hand - phantom measurements confirm this. The loss mechanisms at GSM 900 are compared to those previously reported at 1800 MHz.