Represent the activity of many cells as a Net Dipole +++++t+特 ■一■■=■+十十+++ ==■=■■++十+++ +++++++一一一一一▣ +++++++ ±共++±+中++++ ■=+十十++十 +++++干+合 ■■=■■■+十十+十十 The sum of the individual A sheet of cells with APs Represent each dipoles a Net Dipole cell as a dipole