Performance and electromagnetic compatibility analysis of antennas for hand held mobile telephones

The Finite Integration Algorithm (FIA) is used for the analysis of the Monopole and Radiation-Coupled Dual-L (RCDLA) antennas for personal communications at the GSM frequency of 900 MHz. The two aspects investigated are the electromagnetic-compatibility (EMC) and the performance. Special attention is given to a user wearing glasses, whereby the eddy currents in the frame induce electromagnetic fields in the eye area which is the very sensible area in the human head. It is found that 44% of the power delivered to the monopole is absorbed by the user, compared to only 20% for the RCDLA. The maximal local SAR (Specific Absorption Rate) inside the head for a transmitted power of 1 W for the monopole and RCDLA is 2 mW/cm3 and 0.9 mW/cm3 respectively. This is just reaching the German safety standard (2 mW/cm3 averaged over 10 g) for the monopole, but is less than half this standard for the RCDLA. It is also found that the RCDLA has a bandwidth of only 55 M.Hz, and that the user´s hand has a strong influence on its resonant frequency. The monopole, on the other hand has a large bandwidth, and its impedance is not so sensitive to the presence of the user. For a user wearing glasses with a metalic frame, an increase of 2 dB in the local SAR in the area of the eye close to the phone is found compared to a user without glasses.