Definition
The transfer of an electrical signal from one circuit to another through a capacitor, or through the natural capacitance that exists between two conductors separated by an insulator. Because a capacitor blocks direct current but allows alternating current to pass, capacitive coupling is used to pass AC signals between circuit stages while keeping their DC voltages isolated from each other.
Plain English
A way of passing a changing electrical signal from one part of a circuit to another without letting the steady voltages mix. The signal jumps across a small gap (a capacitor) that lets the wiggle through but blocks the steady part.
Context Anchor
Seen in aircraft electrical systems, avionics wiring, headset noise, and radio interference troubleshooting.
Derivation
Capacitive comes from capacitor, which traces back to the Latin capacitas meaning 'ability to hold' — a capacitor holds electrical charge. Coupling means linking two things together. So capacitive coupling literally means 'linking through a charge-holding device.' That helps because it tells you the link isn't a direct wire — it's through stored charge that responds to changing voltage.
Why Pilots Care
Unwanted capacitive coupling can create static or false signals in radios and instruments, so aircraft wiring uses shielding to prevent it.
Grounding Statement
Two wires running side by side don't have to touch to influence each other — a changing signal in one can induce a matching wiggle in the other through the air gap between them. That is capacitive coupling.
Intuition Check
Do not assume coupling means the wires are physically connected. In capacitive coupling, the circuits can affect each other through the space between them.
Example Sentence 1
The technician suspected capacitive coupling between the audio wiring and a nearby power lead was causing the buzzing in the headset.
Example Sentence 2
Proper spacing and grounded shields in the avionics bay reduce the chance of capacitive coupling between control circuits.