The electric field coupling between aircraft wiring is a result of the
voltage potential existing between an interfering source cable and the sensitive
victim cable. This potential difference causes a current to flow through the
capacitance between the wires, resulting in an energy transfer to the victim
cable. Therefore, at low frequencies where the capacitive reactance between
cables is extremely high, there will be a minimum of coupling. However, where
that capacitive reactance is low, at high frequencies, there will be a higher
degree of coupling.
The capacitive coupling between unshielded aircraft interconnecting wiring
is shown schematically in Figure 4-8.
The voltage (E sub x) electrically coupled to a victim circuit is
characterized by equation 4-3:
E sub x =[Eo C sub c/ C sub b + C sub c] Eq. 4-3
The values of capacitance typically found in aircraft and missile
interconnecting wires are shown in Figure 4-9.