What controls the radar pulse width (PW) by means of a rectangular direct current (DC)?

• A. Antenna
• B. Modulator
• C. Receiver
• D. Power supply

Answer: (B)

Pulse width is determined by how long the transmitter is allowed to emit energy. The modulator acts as the switch that gates the transmitter on and off, using a rectangular DC drive to create a clean, time-defined pulse. When the rectangular DC is applied, the modulator turns the RF output on for a specific interval and then off, so the duration of that drive sets the pulse width. The antenna just radiates the pulse, the receiver processes echoes, and the power supply provides energy, but none of them sets how long the pulse lasts. So the modulator is the component that controls the pulse width by gating the transmitter with a rectangular DC signal. Shorter pulses give better range resolution but less energy per pulse; longer pulses increase energy per pulse but reduce resolution.