Correction of I/Q errors in homodyne step frequency radar refocuses range profiles

An important criterion of any ground penetrating radar is to maximise penetration while maintaining a given resolution. To achieve this, low frequencies must be used for low loss, but high proportional bandwidths are then required to maintain high range resolution. A homodyne step frequency radar is being developed to accommodate these requirements. However the wideband nature of the radar raises problems with I/Q channel errors and mismatches. These errors defocus the correct response by spreading energy across the range profile and introducing an Hermitian image. A well focussed range profile allows maximal side-lobe reduction by windowing. This paper addresses the technique for correcting these effects of common and differential I/Q gain and phase errors by signal processing. We present results obtained from a very broadband homodyne radar where a correction process for common I/Q errors allows the ideal sine response to be recovered in the region of the target response