3D/2D radiation pattern measurement of different GSM phones for EMC applications

Electromagnetic interference of Global System for Mobile Communications (GSM) signals with medical devices and in airplane systems is a known issue. Radiated immunity tests with GSM-modulated signals on equipment in industry are often performed by moving a mobile phone over the Equipment Under Test (EUT). This is often done because it is not always easy to apply the standard radiated immunity method and establish a field uniformity area in industrial environments as per the standard IEC61000-4-3. However, to get meaningful results, information in advance about the antenna radiation pattern of the used GSM phone is indispensable. Here we investigate the radiation pattern of three different GSM mobile phones using a rotatable mount in both elevation and azimuth angles. A step motor was used to rotate the mobile phone in the azimuth level from 0° to 360°, in addition to a manual scan in the azimuth from 0° to 180°. The measurements were performed in a full-anechoic chamber using a GSM signal simulator, horn antennas and a spectrum analyzer. The results include 3D radiation patterns, 2D cross sections and additional characteristics of the GSM beam. The results show that the pattern of GSM mobile phones is not easily predicted and might differ from a phone to another. We also show that 2D shapes do not give enough information about the radiation pattern. In addition, we observe a clear variation between the vertically polarized radiation and the horizontally polarized one.