Quantifying cross modulation effects from pulsed interferers on radar signals

Ultra-wideband RF systems offer a multitude of advantages over narrow band systems. One major point is that these systems can perform multiple functions, like communications, radar and others all using the same aperture. This big advantage of these systems is at the same time their biggest handicap: The wideband receivers are open to much more types of signals compared to narrow band systems. Due to the finite linearity of the receiver input stage, intermodulation and cross modulation between useful and interference signals may occur. For narrow band systems, expected interference signals are mostly of the same type as the useful signal, as only one frequency band is considered. For ultra-wideband systems, all types of interference signals have to be expected, the most prominent being CW like communication signals and pulsed radar signals. This paper gives a theoretical evaluation of the cross modulation effects that occur in pulsed radar systems and verifies these findings with measurements that were made using a state of the art radar demonstrator.