RF Hardware Adaptive Filter Design for Reducing RF Interference in UWB SAR Systems

Author(s):

Benjamin Kirk, Justin Rossler, Emma Lever, Alex Bouvy, Kyle Gallagher, Austin Egbert, Charles Baylis, and Robert Marks

Abstract:

Ultrawide bandwidth (UWB) synthetic aperture radar (SAR) requires access to large swaths of the electromagnetic spectrum (EMS) to perform high-resolution imaging of targets of interest. This large swath of spectrum should begin in the very-high-frequency to lower ultra-high-frequency band to provide the SAR system with obstacle penetration. This portion of the spectrum has become increasingly congested with the proliferation of commercial wireless technologies and the increased need for high-throughput DoD communications systems. This results in the UWB SAR system incurring significant interference while operating in overlapping bands with these other systems. The spectrum changes dynamically with geolocation as well as time. An RF filtering solution is required to alleviate this interference. In conjunction with spectrum situational awareness, this filter will allow the SAR system to adapt to a changing EMS and maintain its performance for target detection. The state of the art both in commercially available devices and the research community is explored, but a solution with the low-loss, high-linearity, operating frequency coverage, and number of notches was not found. In this work, we address this problem through the design of an adaptable RF notch filter.