“Smitek” company has successfully completed design routine and operational tests of a swing-arm spherical near-filed scanner. Main feature of this scanner is the ability to perform a full spherical measurement as well as a measurement in a front hemisphere only. Latter is applicable for tasks when it may be sufficient to reconstruct a far-field gain pattern in a sector (for example, gain patterns with pencil beams) without examining the lateral radiation.
An important factor is that the measurement time is halved compared with the conventional full spherical scan. The amplitude distribution measured on a full sphere together with the amplitude distribution collected from a front hemisphere is presented on the Pic. 1. Measurements were performed for a pyramidal horn at a frequency 1 GHz with no probe correction.
Gain pattern cuts, reconstructed from the corresponding spherical near-field data sets, are presented on the Pic. 2. It can be seen that the gain patterns are nearly equal in a sector .
Pic. 1. The amplitude distribution measured on a full sphere a) together with the amplitude distribution collected from a front hemisphere b) for a pyramidal horn at a freq. 1 GHz.
Pic. 2. Gain pattern cuts of a pyramidal horn at a freq. 1 GHz, reconstructed from the raw data measured on a full sphere, together with E\H plane cuts reconstructed from the amplitude\phase distribution measured on a front hemisphere.