Comparison between head losses of 20 phones with external and built-in antennas measured in reverberation chamber

We have measured the total radiated power of 20 telephones in the free space position and in four talk positions close to a head phantom, and we have from these values calculated the head loss, i.e, the reduction in radiated power when the telephone is located in the talk position compared to in free space. The results show that telephones with built-in antennas are much less sensitive to how the telephone is held than telephones with external antennas. The built-in antennas show about 1 dB lower head loss than external antennas at 1800 MHz.