Which method reduces radiated EMI?

• A. Increasing transmitter power
• B. Using directional antennas
• C. Limiting antenna bandwidth
• D. Separating the transmitting and receiving antennas

Answer: (D)

Reducing radiated EMI comes down to minimizing how much transmitter energy reaches other equipment. Separating the transmitting and receiving antennas increases the physical distance between the source and the sensitive device, which weakens the coupling paths and lowers the field strength that the receiver picks up. In practice, more distance means less energy is intercepted, so interference is reduced across a wide range of frequencies and orientations.

Increasing transmitter power would raise EMI, not reduce it. Limiting antenna bandwidth helps by restricting the emitted spectrum, but it doesn’t address how strongly the energy couples at the receiver’s location. Using directional antennas can shape where energy goes, but EMI can still spread to unintended directions; separation provides a robust reduction regardless of direction or spectrum.