Rapid Small-Antenna Measurements

We give an overview of research performed during previous years on the development of methods for measuring and determining the radiation patterns of small antennas. The work has focused on developing a spherical multi-probe system for measuring the 3-D complex radiation patterns of small antennas, as e.g. used in mobile terminals, without the need to move the device under test during the measurement. A demonstrator system with 32 dual-polarised field probes has been manufactured and evaluated. The frequency range of the measurement system covers most of the current mobile communications systems, i.e. from 800 MHz to 3 GHz. The radius of the measurement sphere is 1 m. The far field is determined with the spherical-wave expansion-based near-field to far-field transformation from the signals measured at each probe port. Since the system allows measuring a 3-D pattern within seconds, it facilitates specific research that would not be feasible with traditional measurement techniques. Some of these new results are presented. Finally, foreseen future developments of these measurement methods are presented.