Mutual Coupling-Based Calibration for the Horus Digital Phased Array Radar

Horus—A Fully Digital Polarimetric Phased Array Radar for Next-Generation Weather Observations

“…In this scheme, array panels are independently calibrated at short-range using a standard gain horn antenna, thereby increasing signal-tonoise ratio and mitigating multipath contamination and resulting in an initially calibrated array (with uniform amplitude and phase excitations). Second, mutual coupling calibration is applied [59] to correct for element-level amplitude/phase differences that may have occurred from the time the recursive calibration was applied to the radar deployment time. Third, after boresight array calibration is conducted, scan-loss correction for the copolar H and copolar V antenna gains are applied as a function of steering angle.…”

“…Unfortunately, any changes in the array performance in the field often result in a need for dismantling the radar and recalibration in a laboratory setting. Fully digital PARs have the potential of using the inherent mutual coupling among individual elements to realign the array after being deployed [59]. This solution to the calibration challenge is an important advantage of fully digital PARs.…”

“…If performed carefully, NF measurements can provide an understanding of root causes of any antenna limitations [94], [95]. For the Horus system, the early work reported in [96] and [97] has continued with a summary included here.…”

“…This concept, which has been used since the early days of such systems [102], is useful for initial calibration and alignment (without the use of near-or far-field test equipment) [103] and in-situ realignment and enforcement of new weightings [19] in digital array systems. Recent activities have been summarized in [96].…”