Figure 7.

Procedure to determine the coupling between antenna pairs. A spherical brain phantom (a) was inserted into a spherical bolus (b). An active (A) and a passive (P) antenna were added inside the bolus. First, the individual fields $E_A$ and $E_P$ of each antenna were determined without the presence of the other antenna. Subsequently, the active antenna was excited with the presence of the passive antenna and the overall coupled field $E_{A+P}$ was determined. A correlation factor between the coupled field $E_{A+P}$ and the passive antenna field $E_P$ was determined. This was found to be proportional to the projection on $U_P$ of the individual field $E_A$ at the location of the passive antenna (c).