Electrical and mechanical uncertainty study in cylindrical near field antenna measurement systems

Resumen

In order to evaluate how mechanical or electrical errors may affect in the final results (i.e. radiation patterns, directivity, side lobe levels (SLL), beam width, maximum and null position…), an error simulator based on virtual acquisitions of the measurement of the radiation characteristics in a cylindrical near-field facility has been implemented [1], [2]. In this case, the Antenna Under Test (AUT) is modelled as an array of vertical dipoles and the probe is assumed to be a corrugated horn antenna. This tool allows simulating an acquisition containing mechanical errors – deterministic and random errors in the x-, yand z-position – and also electrical inaccuracies – such as phase errors or noise –. Then, after a near-to-far-field transformation [3], by comparing the results obtained in the ideal case and when including errors, the deviation produced can be estimated. As a result, through virtual simulations, it is possible to determine if the measurement accuracy requirements can be satisfied or not and the effect of the errors on the measurement results can be checked. This paper describes the error simulator implemented and the results achieved for some of the error sources considered for an L-band RADAR antennas in a 15 meters cylindrical near field system.