Wide-band airborne radar operating considerations for low-altitude surveillance in the presence of specular multipath

Reliable detection of low-altitude platforms while simultaneously maintaining a desired search rate can be extremely difficult due to the presence of multipath. Wide-band operation in combination with frequency diversity is a sensible approach to not only mitigate, but in some cases exploit multipath channel characteristics. While a great deal of knowledge exists for characterizing the frequency dependencies of complicated multipath channels, relatively little attention has been given to examining how this knowledge could be exploited with wide-band radar sensors. The utilization of multipath channel characteristics is considered for the scenario of an airborne wide-band radar sensor performing low-altitude surveillance in a maritime environment. A brief overview of applicable multipath phenomenology is presented leading to a description of the propagation conditions selected for the construction of a representative channel. A generalized wide-band model of the sensor engagement applicable to the resolved and unresolved domains of the interference regime is utilized in combination with the simulated channel. Wide-band short pulse and linear frequency modulation waveforms are employed to consider waveform modulation characteristics in combination with desirable sensor bandwidth and frequency diversity for nominal operation at X-band. A brief discussion on implementation possibilities is also included.