Total radiation efficiency of the standard gain horn antenna measured by using three-antenna method and the developed testbed

Figure 67 of "Report on the development of efficient metrological methods for
key NR OTA RF parametric metrics (e.g. TRP, EIRP), for sub-6 GHz MIMO and
mm-wave massive MIMO systems, and the quantification of the associated
uncertainties (target the upper limits of measurement uncertainties for the
measured quantities given in 3GPP documents e.g. ETSI TR 38.810, TR 38.884)
based on using, for example, direct far-field (DFF), indirect far-field (IFF), near
field-to-far-field (NF-FF), mid field and reverberation chamber (RC) methods with
validation in an interlaboratory comparison"