Theoretical approach of the assessment of the EM field in the vicinity of aperture antennas

In this work, an assessment of the influence of the field probes on the uncertainty in the measurements of the electric and magnetic field in the vicinity of aperture antennas is presented. A uniform aperture distribution is considered because the field of a tapered distribution aperture can be reduced to that of a uniform one. Moreover, the effect of probe size and configuration is presented through a comparison between the theoretically calculated and the expected values. Field probes of a single or more perpendicular dipoles are investigated. The maximum permissible length of the dipoles for an accurate field assessment depends on the field´s gradient. In the regions where the relative amplitude and phase of the electric field along the measuring device does not exhibit considerable variation, even half-wavelength dipoles can be used. It is also found that probes with sizes less than 0.1lambda ensure measurement uncertainty less than 0.5 dB for field variation up to 7 dB/lambda