Empirical phase calibration for multistatic specular meteor radars using a beamforming approach

Specular meteor radars have proven useful for observing mesosphere and lower thermosphere altitudes. More recently, their capabilities have been enhanced by including multistatic configurations. In both cases, monostatic and multistatic, the multiantenna interferometer used to determine the location of the measurements needs to be carefully calibrated in phase. In this work we proposed a technique to calibrate the receiving phases of such interferometers, including the standard five-antenna Jones configuration located on a plane and arbitrary configurations not necessarily located on a plane and not limited to five antennas. Our technique uses beamforming and nonlinear least squares fitting to determine the angle of arrivals that are consistent with the complex spatial coherences of the detected meteors. The optimization process uses a priori information based on the expected angular and altitude distribution of the echoes. The technique is demonstrated using real bistatic data. The obtained distribution of inverse decay time as a function of altitude is shown to be a sensitive and independent quality control feature of the applied calibration.