Impact of Power Amplifier Long Term Memory Effects in Spatial Derivative Superposition Systems

In this letter, the impact of power amplifier (PA) long term memory effects on intermodulation distortion cancellation performance of spatial derivative superposition systems is evaluated. Employing a behavioral model derived from Volterra series analysis, these important nonlinear dynamic effects could be taken into account for evaluating the impairment of the linear characteristics sought in the beam pointing direction. Radiation patterns obtained from simulations of a four-element active array highlight the influence of field effect transistor drain impedance characteristics on the achieved bandwidth. Measurement results, herein reported for the first time, validate the proposed analysis as well as the capability of this technique for improving linearity with spatial selectivity.