Selecting Probe Antennas for Near-Field Antenna Measurements

In summary, two of the most common probe types used in near- eld antenna ranges include the open-ended waveguide and the conical scalar horn. Open-ended waveguide probes have nearly constant gain over a wide beamwidth, while scalar horns provide higher gain with low sidelobe levels that can reduce multipath effects and improve the SNR of measurements. Probes with higher gain can also reduce the required sampling density, decreasing the measurement time and reducing computational burdens. The angular response of scalar horn probes is uniform and easily modeled for probe correction. The scalar horn may be combined with an OMT to enable simultaneous measurements of orthogonal polarizations. Low cross-polarization responses are desired to minimize measurement errors, and isolators should be used to minimize mutual coupling between the probe and the AUT.