Effects of Range Doppler-rate Coupling on High Frequency Chirp Radar for Accelerating Targets

Range Doppler coupling is a range bias resulting from the use of linear frequency modulated waveforms. This coupling impacts radar returns of highly accelerating targets resulting in apparent range walk across a processing interval. Because of this, methods for detecting fast objects with long integration times introduce unwanted artefacts to chirp radars utilising low bandwidths and low repetition frequencies. This paper details that in addition to the range bias, range Doppler coupling artefacts impact higher order measurements, and also describes how these affects can be mitigated. Results of radar returns from satellites demonstrating sensitivity improvements are included, illustrating that mitigating range Doppler-rate coupling will benefit any time-frequency method attempting accelerating target detection.