Factors limiting the upper frequency of mm-wave spherical near-field test systems

Antennas operating at mm-wave frequencies have led to the development of spherical near-field test systems that have to function at higher frequencies than before. This paper addresses some of the factors limiting the upper frequency bound of spherical near-field test systems in terms of what is practical with current technology. This includes mechanical positioning systems, RF sub-systems and the spherical near-field sampling requirements. Correction techniques that have been developed to enhance the performance of such measurement systems are also presented.