Experimental verification of the far-field approximation for a mobile phone antenna

The aim of this study was to verify the validity of the far-field approximation for a mobile phone during a call. Typical models of mobile phones were used to measure the electromagnetic field emitted during a call at various distances from the mobile phone using a selective radiation meter Narda SRM 3000. The near-field and far-field theories were applied to obtained measurements. As a result, the far-field approximation could be applied also at a few centimeters from the mobile phone. Nevertheless, it resulted that the best accuracy of the application of the far-field approximation to mobile phones working is obtained at distances larger than 40cm, in agreement with the theoretic formulations relative to the condition that the antenna dimension is lesser than the wavelength of microwave radiation used by mobile phone working.