How do I perform pulsed S-parameter measurements on a power amplifier?

Pulsed S-parameter measurements on a power amplifier characterize the amplifier's RF behavior under pulsed operating conditions, where the bias is applied only during short duty-cycle pulses to replicate the actual operating environment (as in radar transmitters) or to prevent self-heating that would alter the device's performance characteristics. The measurement technique involves: configuring the VNA for pulsed mode (the VNA generates and receives RF signals that are synchronized with the bias pulse; the RF stimulus is applied only during the active portion of the pulse, and the VNA receiver gates its measurement window to capture data only during the stable portion of the pulse), synchronizing the pulse timing (the DUT bias pulse, the VNA RF stimulus pulse, and the VNA receiver measurement window must be precisely time-aligned; the bias pulse turns on first (typically 1-10 microseconds before the RF), the RF stimulus is applied during the bias-on interval, and the receiver captures data during the settled portion of the pulse, avoiding the leading and trailing transients), setting the pulse parameters (pulse width: typically 1-100 microseconds, matching the DUT's operational pulse width; duty cycle: typically 0.1-10%; pulse repetition interval: 10-1000 microseconds), and calibrating the pulsed measurement system (the VNA must be calibrated in pulsed mode using the same pulse parameters as the measurement; calibration standards are measured under pulsed conditions to account for the pulsed receiver's different noise floor and dynamic range compared to CW mode).