Characterisation of a Fibre-Optic Active Probe for Compensation of the Test-Zone Field

Compensation of the non-ideal Test Zone Field (TZF) in which an antenna under test is characterised requires a precise determination of the incident electric field. In order to perform spherical measurements of the test zone, a probe is, thus, inevitable which interacts with the TZF as slightly as possible. Therefore, a fibre-optic probe is used which primarily consists of dielectric parts. To correct for the measuring test-zone probe, a thorough determination of its radiation pattern and polarisation ratio is mandatory. To this end, full-wave simulations are carried out on the probe model and compared to spherical near-field measurements, thereby ensuring an accurate probe characterisation. Subsequently, the probe is included to simulated TZF data via spherical wave expansion in order to demonstrate the suitability of this fibre-optic probe for measuring the incident field and the importance of test-zone probe correction.