where G_R is the gain of the reader antenna, G_(T )is the gain of the tag’s antenna, placed on the target. P_in is the power accepted by the antenna of the reader unit. The polarization mismatch η_p between the reader and the tag is here considered unitary since they have been properly aligned in all the measurements. G_T τ≡(G_T ) ̂ is the realized gain of the tag.