A 60 GHz Dual-Polarized Probe for Spherical Near-Field Measurements

Dual-polarized probe systems can be used with some of the advantages: the two electric field components are simultaneously measured within a single scan, amplitude and phase drift affects the two polarization components in the same way, and there is no need for mechanical rotation of the probe. In this work we design and test a dual-polarized probe system at 60 GHz - a conical horn, including the elements: SPDT (single pole double throw) switch, an OMT (orthomode transducer) both components with 40 dB isolation - a square to circular transition (3.75 mm to 3.58 mm), cables and two coaxial to waveguide adapters up to 67 GHz for OMT-switch connection.

A 27 dBi gain conical horn is designed by using WIPL-D software and in-house manufactured. The 60 GHz probe system is being assembled and tested in planar near-field (PNF) setup at DTU. The results are validated by comparison with WIPL-D simulations, showing a good agreement within the validity region, down to -30 dB pattern levels.

Channel balance is carried out to compensate for the amplitude and phase differences between the signals at the OMT ports.