Which type of coupling results from energy entering a system through ventilation holes or gaps?

The type of coupling that results from energy entering a system through ventilation holes or gaps is referred to as direct coupling. In electronic warfare and systems engineering, direct coupling typically involves an unintentional pathway for electromagnetic energy to enter a system, allowing it to interfere with the intended operation. This phenomenon often occurs when there are openings in shielding or other barriers that are meant to contain electromagnetic signals.

Direct coupling can lead to vulnerabilities in the system since it may permit external energy, such as electromagnetic interference or signals from nearby equipment, to impact the performance and reliability of sensitive electronics. Understanding direct coupling is essential for designing systems that are robust against unintentional access points for interference, helping to maintain operational integrity.

The other types of coupling mentioned pertain to different methods of energy transfer or interference but do not specifically relate to the entry through ventilation holes or gaps as direct coupling does.