DERIVING FAR-FIELD PERFORMANCE PARAMETERS FROM NEAR-FIELD AMPLITUDE MEASUREMENTS OF WIRELESS DEVICES

摘要

The CTIA (The Wireless Association - www.ctia.org) were the first to publish a widely accepted test plan for antenna performance testing of "live" mobile phones[1]. The test plan describes the use of phantom heads and involves recording transmitted power and receiver sensitivity information over a full sphere to derive parameters such as Total Radiated Power (TRP) and Total Integrated Sensitivity (TIS). The test plan, has until now, assumed that testing is performed in the far-field at test distances greater than 2D~(2)/lambda. For typical mobile phone frequency and device test diameters (assumed 300mm in the CTIA test plan), this has not been a constraint. However, as such testing evolves to include the various versions of IEEE 802.11 combined with new devices such as larger laptops and other consumer electronics, a far-field test requirement would lead to very large test facilities. Using experiments and rigorous simulations, this paper will show that for the commonly accepted performance criteria, the far-field requirement is unnecessarily strict. A minimum distance requirement based on the geometry and probe pattern is proposed which will ensure that the performance parameters (TRP, TIS, and others) are obtained with insignificant loss of accuracy.