Customised spherical near-field system for the mobile phone market

Antenna measurements have been dominated by an assumption that the antenna is a removable component of the system where it is applied; the approach to measure the antenna is to remove it, and place it in a generic test system to measure gain, patterns, etc. Although this technique still applies to many antenna measurements, it does not work well in some applications. Generic antenna measurement systems in some cases are not capable of providing the necessary accuracy. Mobile phone antennas measured by placing the phone on a roll over azimuth positioner are convenient, but not representative of the way they are used in a real life situation. Mobile phone antennas exhibit significant electromagnetic coupling to the human body holding the phone; therefore, the antenna should be measured in situ with a person holding the phone, or for practical reasons, with a mannequin arranged such that it can hold the phone. The mannequin is placed on an azimuth positioner; a near-field probe is moved on a very accurate circular arch from zenith to a significant angle below the mobile phone horizon plane. In this system the shielded chamber is an integral part of the system. A description of the chamber and system, and measured results are provided.