Measurement technique to assess the impact of RF power amplifier memory effects on radar performance

Future Digital Array Radars (DARs) will have the capability to create arbitrarily shaped beams on receive, and flexible beam shaping on transmit. Their multifunction design supports a diverse set of waveforms, which when exercised can induce transient amplitude and phase shift in their solid state High Power Amplifies (HPAs). This transient is due to electrothermal effects and has duration in the order of 100´s of microseconds to milliseconds, and is identified in this paper as a potential problem for future DARs. The time varying amplitude and phase can potentially impact the effectiveness of Pulse Doppler and Moving Target Indicator (MTI) processing in addition to changing antenna pattern characteristics over the duration of a Coherent Processing Interval (CPI). The purpose of this paper is to present a technique to measure electrothermal memory effects as applied to multifunction DARs.