This question deals with the "absolute gain method", see the coursebook chapter 7.3.1. Two antennas are identical (i.e., Gt=Gr=G ), one is transmitting and one receiving. The antennas are separated by a 2.6-m distance. A calibrated vector network analyzer measures the numerical value of the power transmission coefficient (i.e., |S21|2=PrPt ) between the antennas at 2.4 GHz: |S21|2=0.0059 (corresponds to S21dB=22.3 dB ). Assume the free-space and far-field conditions and perfect polarization and impedance matching. What is the gain G of the antennas? A calibrated vector network analyzer means that the effect of the measurements cables is "de-embedded" from the measurement result - i.e., the transmitted and received powers (Pt , Pr ) are defined at the input port of the antennas. See the vertical dotted lines in the figure to illustrate the reference level of the calibration