Rapid spherical 3-D field measurement system for mobile terminal antennas

A novel rapid spherical 3-D field measurement system for mobile terminal antennas, that is capable of determining the radiation pattern of a mobile terminal antenna without rotating the antenna, is introduced. The system is based on measuring the complex radiated field at 32 locations on a spherical surface. At each location the field in two orthogonal tangential polarizations is measured. The radius of the measurement sphere is about 1 m. The spherical wave expansion technique is used to determine the far field in all directions from the 64 field samples. System can be operated either with a vector network analyzer (VNA) or with a spectrum analyzer. The operation of the system with a spectrum analyzer, provided a phase-retrieval network is used, allows the determination of the complex radiation properties of a real mobile phone without attaching a cable to the mobile phone. This is important since determining the diversity properties of mobile phones requires the knowledge of the complex field. In this paper we use the system with VNA and we focus on describing the electromagnetic properties of the system.