Very-near-field testing of large antennas in lab environment

This article presents a compact set-up for characterization of large antennas. The proposed technique uses EMSCAN´s RFxpert system. Multiple near-fields scans, 0.16m² each, are patched together to capture near-field radiation from large antennas. The effect of the width of the scan area and the lab environment is investigated herein for a reconfigurable base station antenna. Far-field patterns at 750MHz and 1850MHz show good agreement with chamber data in terms of shape, beamwidth, and directivity. Based on the investigations, the use of an absorber sheet for suppression of higher order interactions between the scanner and the antenna is strongly recommended. It is also demonstrated that a scan area as narrow as the width of the scanner itself is often sufficient to capture the fan-shaped radiation pattern of the base-station antenna.