Modulation error in active-aperture phased-array radar systems

The authors address range sidelobe (RSL) suppression in the context of active arrays defined as a phased array antenna driven by distributed solid-state element-level modules or tube-driven subarray-level transmitters and receivers. In assessing signal effects, the interaction of the waveform spectrum and the antenna pattern must be considered in the context of module-to-module amplitude and phase tracking variation. The basic methodology for achieving low RSL performance in active arrays using modulation error compensation is briefly reviewed. The associated performance limits imposed by modulation error decorrelation and noise-limited error characterization are delineated. Emphasis is placed on presenting these performance trades in an analogous fashion to those associated with narrowband pulse Doppler mechanization so as to permit ready comparison of implementation requirements